113 results on '"Topp B"'
Search Results
2. Value chain stakeholder preferences are misaligned with economic weights derived from the bio-economic model: what is the effect on the ranking of candidates?
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Kern, S., Santos, B., Topp, B., Cave, R., Bignell, Grant W., Mulo, Shane, Hardner, C., Kern, S., Santos, B., Topp, B., Cave, R., Bignell, Grant W., Mulo, Shane, and Hardner, C.
- Abstract
While breeding values for key traits are often known by horticultural crop breeders, the definition of each trait’s economic component has remained a grey area. The lack of pertinent quantitative data to derive economic weights limits the capacity of breeders to capture the direction the industry wishes to take and select cultivars accordingly. Price signal (all sources of income and costs related to a trait) is a relevant source of data to determine the economic weight of traits through bio-economic modelling. However, if price signals for a trait are only partially captured, its weight may become distorted. Using industry stakeholder preferences to rank the trait improvements may address price signal gaps. Using Kern et al. (2021), choice analysis data, the difference between weights derived from bio-economic modelling and stakeholder preferences for yield (tree age 10-20), canopy width, and kernel recovery was 10, 0, and -16%, respectively. The ranking of 30 macadamia cultivars was based on two sets of weights. The candidates’ genetic values, yield (kg tree‑1) for tree age 0-8, kernel recovery (%) and canopy width (m), both at tree age 8, were used to determine the candidates’ profitability. Results showed a correlation (r=0.997) between cultivar rankings using weights derived through the bio-economic model and stakeholders’ preferences. This indicates that despite the wide range of profitability between candidates (from $ 10,000 to 92,000), integrating stakeholders’ preferences to the economic weights did not significantly alter the ranking of the 30 candidates. Further research must be done to evaluate the impact of large differences between weights derived from bio-economic modelling and stakeholder preferences on economic weight. The results of this research would confirm the necessity of investing in a formal and industry-approved bio-economic model, or to develop a time-efficient approach emphasizing stakeholders’ preferences to determine economic weights.
- Published
- 2023
3. Impact of storage on in vitro bioaccessibility of anthocyanins in ‘Rubycot’ plumcot and ‘Queen Garnet’ plum
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Kodagoda, G.K., primary, Hong, H.T., additional, Addepalli, R., additional, Topp, B., additional, Sultanbawa, Y., additional, O'Hare, T.J., additional, Netzel, M.E., additional, and Osborne, S., additional
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- 2023
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4. Characterization of accessions and species of Macadamia to stem infection by Phytophthora cinnamomi
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Akinsanmi, O. A., Neal, J., Drenth, A., and Topp, B.
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- 2017
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5. Comparison of long-read methods for sequencing and assembly of a plant genome
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Murigneux, V, Rai, SK, Furtado, A, Bruxner, TJC, Tian, W, Harliwong, I, Wei, H, Yang, B, Ye, Q, Anderson, E, Mao, Q, Drmanac, R, Wang, O, Peters, BA, Xu, M, Wu, P, Topp, B, Coin, LJM, Henry, RJ, Murigneux, V, Rai, SK, Furtado, A, Bruxner, TJC, Tian, W, Harliwong, I, Wei, H, Yang, B, Ye, Q, Anderson, E, Mao, Q, Drmanac, R, Wang, O, Peters, BA, Xu, M, Wu, P, Topp, B, Coin, LJM, and Henry, RJ
- Abstract
BACKGROUND: Sequencing technologies have advanced to the point where it is possible to generate high-accuracy, haplotype-resolved, chromosome-scale assemblies. Several long-read sequencing technologies are available, and a growing number of algorithms have been developed to assemble the reads generated by those technologies. When starting a new genome project, it is therefore challenging to select the most cost-effective sequencing technology, as well as the most appropriate software for assembly and polishing. It is thus important to benchmark different approaches applied to the same sample. RESULTS: Here, we report a comparison of 3 long-read sequencing technologies applied to the de novo assembly of a plant genome, Macadamia jansenii. We have generated sequencing data using Pacific Biosciences (Sequel I), Oxford Nanopore Technologies (PromethION), and BGI (single-tube Long Fragment Read) technologies for the same sample. Several assemblers were benchmarked in the assembly of Pacific Biosciences and Nanopore reads. Results obtained from combining long-read technologies or short-read and long-read technologies are also presented. The assemblies were compared for contiguity, base accuracy, and completeness, as well as sequencing costs and DNA material requirements. CONCLUSIONS: The 3 long-read technologies produced highly contiguous and complete genome assemblies of M. jansenii. At the time of sequencing, the cost associated with each method was significantly different, but continuous improvements in technologies have resulted in greater accuracy, increased throughput, and reduced costs. We propose updating this comparison regularly with reports on significant iterations of the sequencing technologies.
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- 2020
6. Metabolic adaptations to chronic glucose infusion in rats
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Topp, B. G., McArthur, M. D., and Finegood, D. T.
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- 2004
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7. Low-chill cultivar development.
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Topp, B. L., primary, Sherman, W. B., additional, and Raseira, M. C. B., additional
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- 2008
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8. Macadamia nuts – good fats, bad fats, and biofortification
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O’Hare, T.J., primary, Hong, H.T., additional, Pun, S., additional, Liu, D., additional, Torrisi, C., additional, Mai, T., additional, Alam, M., additional, Russell, D., additional, and Topp, B., additional
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- 2020
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9. Variability of initial and final nut set in elite macadamia selections using different pollination methods
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Howell, E., Russell, D., Alam, M. M., Topp, B. L., Howell, E., Russell, D., Alam, M. M., and Topp, B. L.
- Abstract
Selection for yield in macadamia is a major component of the Australian industry breeding program because of its high economic weighting. Pollination success initially determines the nut set and consequently the yield of a tree. The method of pollination may affect the initial nut set (INS) and final nut set (FNS). Tested genotypes are currently involved in a regional cultivar trial across northern New South Wales and South East Queensland, Australia. Pollinations took place in a high density macadamia orchard containing 12 elite genotypes. Each genotype was pollinated using three methods; autogamous pollination, supplementary cross pollination by hand and natural open pollination. INS was recorded 90 days post pollination and FNS 180 days post pollination on 15 racemes tree-1 with 3 reps for each genotype. Pollination methods varied for both INS and FNS. The most efficient pollination method across genotypes was supplementary cross pollination. Autogamous pollination had low INS and lower FNS and the highest mean abscission rate (83.7%). Supplementary cross pollination can increase nut set and cultivars 'HAES 741' and 'HAES 344' were identified as compatible pollinisers. From the elite selections five genotypes were identified as self-fertile by producing nut set through the autogamous pollination method. The greatest difference between the initial and final nut set was for autogamous pollination. Nut set could be utilised for selection of potential high yielding candidate macadamia cultivars.
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- 2018
10. Variation in floral and growth traits in a macadamia breeding population
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O’Connor, Katie M., Hardner, C. M., Alam, M. M., Hayes, B. J., Topp, B. L., O’Connor, Katie M., Hardner, C. M., Alam, M. M., Hayes, B. J., and Topp, B. L.
- Abstract
Macadamias are grown commercially around the world for their edible nuts. Identifying elite macadamia breeding selections with high yield potential is difficult due to the polygenic control of the trait, and more importantly the low heritability of yield. Indirect selection for yield may be possible through identification of correlated traits that have higher heritability, and are more efficiently measured. This study aimed to investigate component traits for yield by dissecting floral and growth traits of macadamia, including: raceme length, rachis width, floret density, number of florets raceme-1, raceme density, and trunk circumference. This is a preliminary study of 143 seedling progeny from 33 families across two sites in Bundaberg, Queensland, Australia, planted between 2001-2003. Average raceme lengths were variable between families, ranging from 10.2 cm in the '344' × '804' family to 21.1 cm in 'A38' × '816' progeny. Raceme length was significantly correlated with number of florets per raceme (rp=0.85 and rg=0.91, p<0.001), whilst raceme length was negatively correlated with floret density (rp=-0.30, p<0.001). Raceme length, raceme density and number of florets raceme-1 were statistically different between families (p<0.01). This paper shows that it is useful to identify component traits that may be more efficient to measure in order to indirectly select for complex traits like yield. These are preliminary findings of a larger study in which flowering characteristics will be compared with nut and shell characteristics and yield. Additionally, these findings will inform genomic selection models for yield prediction, as well as genome wide association studies for component traits.
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- 2018
11. Broad-sense heritability and inter-trait relationships in young macadamia architecture, flowering and yield
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Toft, B. D., Alam, M. M., Topp, B. L., Toft, B. D., Alam, M. M., and Topp, B. L.
- Abstract
Macadamia in the orchard environment is relatively unaltered from its natural form, and there is considerable scope to change vegetative and reproductive architecture for improving yield and related traits through breeding. An understanding of genetic and environmental control mechanisms and the dynamics between vegetative and reproductive characteristics are useful to identify the most important traits for improvement. In breeding programs, considerations of the heritability of vegetative traits are usually limited to tree scale measurements such as canopy volume. Here we studied the broad-sense heritability (H) of characteristics that constitute the macadamia canopy and yield at multiple architectural scales, and also documented relationships between vegetative and reproductive traits. Cutting-grown clones of 15 macadamia genotypes were subsampled from a breeding trial planted in 2011 in South East Queensland, Australia. At the tree scale, canopy volume had very low H (0), suggesting a strong environmental influence. Detailed measurements of individual canopy components give insight to more complex interactions within the canopy. Some vegetative architectural characteristics, such as branch number, average internode length and growth unit (GU) length had medium H (0.31-0.39), and node number per GU had high H (0.57). Other canopy components such as length of primary branch axes and primary branch cross-sectional area (BCA) displayed very low heritability (0-0.05), and are likely to be mainly controlled by environmental conditions. H values were low for yield and nut counts (0.16-0.21), except nuts per raceme (0.43). Heritability was medium to high for other reproductive characteristics (0.34-0.70) that may indirectly relate to yield. Understanding the relationships within and between vegetative and yield traits at different architectural scales informs the choice of multiple useful traits, and will aid the breeding of future elite macadamia cultivars. Genetic corr
- Published
- 2018
12. Early growth and graft success in macadamia seedling and cutting rootstocks
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Alam, M. M., Wilkie, J., Topp, B. L., Alam, M. M., Wilkie, J., and Topp, B. L.
- Abstract
Rootstocks play a vital role in growth and productivity of tree crops through water and nutrient translocation and signal transduction to the scion. Early vigour and graft compatibility of rootstocks are important for further growth and development of the scion, and hence for productivity. This study aimed to identify the variability of early growth and graft success of cuttings and seedlings of different species, cultivars and breeding lines of macadamia that will be subsequently screened in a macadamia rootstock field trial. The experiments were conducted in a mist house at Maroochy Research Facility, Nambour. The experiments comprised macadamia seedlings and cuttings of eight commercial cultivars, fifteen breeding lines, and different sources of wild germplasm of Macadamia tetraphylla, M. jansenii and M. ternifolia. All the existing cultivars and breeding lines in the study are derived from M. tetraphylla and/or M. integrifolia species. There was significant variation among the genotypes in cutting survival and growth rates for both seedlings and cuttings. The study identified a breeding line (BHI2) which produces strong cutting root systems with better striking rates (100%) than existing rootstock cultivars. Cutting survival rate was greatest in standard macadamia rootstocks (79%) and least in M. ternifolia (46%). Growth rate varied depending on the genotype and the method of propagation. LSQUOH2RSQUO seedlings were greatest for height increase rate, while cuttings of M.jan3, M. ter1, M.ter3, BHI1, BHI2, BHY1, 'A268', 'A4', 'D4' and 'Daddow' showed greater growth in height than 'H2'O. Both seedlings and cuttings of BHI2, cuttings of BDW4, M.ter1, M.jan3, BHY1, and seedlings of M.tet2 had greater stem diameter increase rate than 'H2'. Among groups, standard rootstocks had the greatest rate of increase in height and breeding progeny of high index value had the greatest rate of stem diameter increase. Graft success was significantly higher in seedlings than cutting
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- 2018
13. Variation in precocity in a macadamia breeding population
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Alam, M. M., Howell, E., Hardner, C. M., Topp, B. L., Alam, M. M., Howell, E., Hardner, C. M., and Topp, B. L.
- Abstract
Genetic improvement of macadamia (Macadamia integrifolia and M. tetraphylla) is still in its early stages. The industry breeding program in Australia is only two to four generations removed from wild germplasm. There are extensive opportunities to improve this crop. Seedling trees have a long juvenile phase and can take up to 6 years to produce fruit. Seedling juvenility impedes the efficiency of the breeding cycle and cultivar juvenility increases the financial risk to the growers. Developing early producing precocious cultivars may reduce these risks and provide farmers with earlier economic returns. Genetic variability of precocity is an important resource that can be used to breed improved macadamias. Experimentation on 39 open pollinated families of diversified genotypes identified significant genetic variation for precocity among 692 progeny. Six progeny from six different families produced flowers at age 3. A total of 101 progeny from 31 families produced flowers and nuts at age 4. Open pollinated families of 'A538', 'A38', 'D4', 'A268', 'A4' and M. jansenii were the most precocious. Genotypes used as parents from Hidden Valley Plantations (HVP) produced the most precocious cultivars. There was a strong correlation between flowering intensity and early yield. The assessment of precocity among genotypes and families will allow the use of a tandem selection strategy, which is aimed to reduce the breeding cycle for selecting high yielding cultivars.
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- 2018
14. Molecular tools for improved productivity in Queensland plum orchards
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Ko, L., Russell, D., Goodrich, B., Berecry, R., Topp, B., Ko, L., Russell, D., Goodrich, B., Berecry, R., and Topp, B.
- Abstract
Most Japanese plum cultivars are self-infertile. In commercial orchards, cross-compatible pollinisers have to be interplanted to ensure fruit set. The self-incompatibility is controlled by S-loci in the pistil and pollen, which are tightly linked to each other. The Prunus S-RNase-specific PCR primers Pru-C2 and PCE-R were used to study candidate compatible pollinisers for the cultivar 'Queen Garnet', known for its high nutritional value. A total of 13 genotypes, including 'Queen Garnet', three other cultivars and nine DAFF breeding lines, were tested. 'Queen Garnet', which possesses gh S-haplotypes, shares none or only one S-haplotype with the other three cultivars and five of the DAFF breeding lines. Not only must an ideal polliniser be cross-compatible in terms of S-haplotype, but it must also overlap in flowering with the main cultivar and produce sufficient quantities of viable pollen. Based on these three criteria, lines ARF25, ARF86, ARF95 and ARF98 were identified for interplanting one row in five to ensure pollination each year and for ease of harvesting. Implementation of this pollination strategy coincided with a 50-fold increase in 'Queen Garnet' fruit yield between 2012-2013 and 2013-2014. While this increase may be partially due to tree maturity and environmental conditions, there is an expectation of up to another 13-fold increase in the following years as trees develop and mature within this improved pollination environment.
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- 2016
15. Variation of cutting rooting ability in cultivated and wild species of Macadamia
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Russell, D. M., Neal, J. M., Mayer, R., Bell, D., Topp, B. L., Russell, D. M., Neal, J. M., Mayer, R., Bell, D., and Topp, B. L.
- Abstract
In Australia, macadamia trees are commonly propagated by germinating rootstock seed and grafting when seedlings reach a suitable size. The production of grafted trees is a protracted and complex process, however, propagation of macadamia via cuttings represents a simpler and faster method of multiplication. Macadamias have traditionally proven difficult to propagate from cuttings, and while recent developments in the process have improved success rates, substantial variation in rooting ability between cultivars and species has been reported. The cultivar 'Beaumont' (Macadamia integrifolia × M. tetraphylla) is commonly propagated by cutting for use as a rootstock, and is relatively easy to strike while other cultivars are more difficult. There is speculation that Hawaiian cultivars are more difficult to strike from cuttings than Australian cultivars due to species and genetic composition. In this experiment, cuttings of 32 genotypes were evaluated for rooting ability. Each genotype's species profile was estimated using historical data, and used to determine species effects on survival (percentage) and rooting ability (rating 0-2). M. jansenii (100%), M. tetraphylla (84%) and M. integrifolia/tetraphylla hybrids (79%) had the highest success rates while M. integrifolia (54%) and M. ternifolia (43%) had the lowest survival. Rooting ability of M. jansenii (1.75) was significantly higher than M. ternifolia (0.49) but not significantly higher than M. tetraphylla × M. integrifolia with (1.09), M. tetraphylla (1.03) or M. integrifolia (0.88).
- Published
- 2016
16. Preliminary evaluation of macadamia rootstocks for yield and tree height
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Neal, Jodi, Kelly, Alison M., Hardner, C. M., McConchie, C., Topp, B. L., Neal, Jodi, Kelly, Alison M., Hardner, C. M., McConchie, C., and Topp, B. L.
- Abstract
Rootstock has profound effects on traits such as yield and tree size in various horticultural industries, however relatively little is known about rootstock effects for macadamia. In this study, 12 cultivars were propagated as open-pollinated seedling and clonal rootstocks, and own-rooted cuttings. The same cultivars were also used as scions, and grafted to a subset of rootstocks, then planted at four trial locations. In this preliminary analysis, rootstock accounted for 19% of the variance in yield compared with 72% for scion, and 23% in height compared with 72% for scion. There was no interaction between rootstock and scion for yield, and only a small effect for height. The interaction between rootstock and propagation method (seedling, clonal, own roots) was not significant for height. A small effect was observed for yield, with the own roots treatment producing significantly lower yield than grafted trees for all rootstock cultivars except 'HAES 849'. 'H2' seedling rootstock produced a cumulative yield to age 10 years of 11.1 kg tree -1 compared to the highest yield of 13.6 kg tree -1 for 'Beaumont' clonal rootstocks. 'H2' seedling rootstock produced 4.8 m trees at age 11 years, compared to the smallest grafted tree which was 'HAES 849' seedling at 4.7 m.
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- 2016
17. Overview of the Australian macadamia industry breeding program
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Topp, B., Hardner, C. M., Neal, Jodi, Kelly, Alison M., Russell, D., McConchie, C., O'Hare, P., Topp, B., Hardner, C. M., Neal, Jodi, Kelly, Alison M., Russell, D., McConchie, C., and O'Hare, P.
- Abstract
Macadamia (Macadamia integrifolia Maiden and Betche and M. tetraphylla L.A.S. Johnson) is an Australian-native, evergreen nut tree adapted to the subtropics. It is the basis of an international industry producing highly valued kernels. Australia is the world leader in production, with about 6 million trees planted on 17,000 ha. Industry funding for an Australian breeding program commenced in 1996, and over 3500 hybrid seedlings were produced and field-planted from 1998 to 2003. Industry participation has involved use of grower properties for progeny field trials, review of outcomes by an industry steering group and consultation with industry on the important traits in new cultivars. Key selection traits are cumulative nut yield per tree to age 8, tree height, canopy width, kernel recovery and nut quality. Quantitative selection methods were used to identify elite selections for commercial testing and for use as parents. The mean cumulative nut-in-shell yield to age 8 for the top 20 seedlings planted from 2000-2003 was 39% higher than the best five cultivars in the same trials. A second generation of hybrid seedlings is being produced using these elite selections, with 2296 seedlings planted from 2011 to 2014. We discuss strategies to improve breeding efficiency and future plans for a husk spot disease nursery, use of wild species and rootstock screening.
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- 2016
18. Molecular tools for improved productivity in Queensland plum orchards
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Ko, L., primary, Russell, D., additional, Goodrich, B., additional, Berecry, R., additional, and Topp, B., additional
- Published
- 2016
- Full Text
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19. Overview of the Australian macadamia industry breeding program
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Topp, B., primary, Hardner, C.M., additional, Neal, J., additional, Kelly, A., additional, Russell, D., additional, McConchie, C., additional, and O’Hare, P., additional
- Published
- 2016
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20. Characterization of accessions and species ofMacadamiato stem infection byPhytophthora cinnamomi
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Akinsanmi, O. A., primary, Neal, J., additional, Drenth, A., additional, and Topp, B., additional
- Published
- 2016
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21. Bioactive anthocyanins in ‘Queen Garnet’ plum – maturity and bioavailability
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Netzel, M.E., primary, Fanning, K., additional, Russell, D., additional, Stanley, R., additional, and Topp, B., additional
- Published
- 2015
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22. TESTING LOW CHILL PEACHES AND NECTARINES IN SUBTROPICAL AND TEMPERATE QUEENSLAND, AUSTRALIA
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Russell, D., primary, Bignell, G., additional, Neal, J., additional, and Topp, B., additional
- Published
- 2015
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23. USE OF THE MEXICAN PEACH 'NIEVE' FOR BREEDING NEW CULTIVARS IN AUSTRALIA
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Topp, B., primary, Pérez, S., additional, Krolow, D., additional, Correa, E., additional, Russell, D., additional, and Neal, J., additional
- Published
- 2015
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24. Biofortified produce – Queen garnet, a new high anthocyan plum
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Netzel, M., primary, Bobrich, A., additional, Topp, B., additional, Russel, D., additional, Netzel, G., additional, Flanagan, B., additional, Gidley, M.J., additional, and Fanning, K.J., additional
- Published
- 2014
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25. Pericarps retained in the tree canopy and stomatal abundance are components of resistance to husk spot caused by Pseudocercospora macadamiae in macadamia
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Akinsanmi, O. A., Topp, B., Drenth, A., Akinsanmi, O. A., Topp, B., and Drenth, A.
- Abstract
Pseudocercospora macadamiae Beilharz, Mayers and Pascoe infects macadamia fruit via stomata causing husk spot disease. Information on the variability of fruit stomatal abundance, its association with diseased fruit pericarps (sticktights) that are retained in the tree canopy, and its influence on the husk spot intensity (incidence, severity and lesion number) among macadamia genotypes is lacking. We examined a total of 230 macadamia trees comprising 19 cultivars, 56 wild germplasm accessions and 40 breeding progeny, for the prevalence of sticktights and husk spot intensity over three production seasons. We observed a strong association between the prevalence of sticktights and disease intensity indicating its usefulness as a predictor of husk spot and as a useful phenotypic trait for husk spot resistance selection in breeding programmes. Similarly, stomatal abundance varied among macadamia genotypes, and a significant linear relationship (P < 0.001; 93%) was observed between fruit stomatal abundance and husk spot for all the macadamia genotypes analysed, confirming the utility of that trait for disease resistance screening. The genotypes were grouped into disease resistance groups. Correlations between fruit stomatal abundance, disease intensity and prevalence of sticktights revealed that the numbers of sticktights, and relative stomatal abundance were the main factors influencing the intensity of husk spot among macadamia genotypes. This is the first comprehensive study of natural variation of stomatal abundance in Macadamia species that reveals genetic variation, and provides relevant relationships with disease intensity and the prevalence of sticktights. The phenotypic plant traits indentified in this study may serve as selection tools for disease resistance screening in macadamia breeding programmes.
- Published
- 2012
26. INCREASING ANTHOCYANIN CONTENT IN QUEEN GARNET PLUM AND CORRELATIONS WITH IN-FIELD MEASURES
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Fanning, K., primary, Edwards, D., additional, Netzel, M., additional, Stanley, R., additional, Netzel, G., additional, Russell, D., additional, and Topp, B., additional
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- 2013
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27. VERMICULITE IMPROVES EARLY DEVELOPMENT AND SURVIVAL OF LOW CHILL STONE-FRUIT EMBRYOS RESCUED IN VITRO
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Hamill, S., primary, Promchot, S., additional, Bignell, G., additional, Giles, J., additional, and Topp, B., additional
- Published
- 2009
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28. Beta-cell mass dynamics in Zucker diabetic fatty rats. Rosiglitazone prevents the rise in net cell death.
- Author
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Finegood, Diane T., McArthur, M. Dawn, Kojwang, David, Thomas, Marion J., Topp, Brian G., Leonard, Thomas, Buckingham, Robin E., Finegood, D T, McArthur, M D, Kojwang, D, Thomas, M J, Topp, B G, Leonard, T, and Buckingham, R E
- Subjects
PANCREATIC beta cells ,TYPE 2 diabetes ,ANIMAL models in research - Abstract
The evolution of diabetes in the male leptin receptor-deficient (fa/fa) Zucker diabetic fatty (ZDF) rat is associated with disruption of normal islet architecture, beta-cell degranulation, and increased beta-cell death. It is unknown whether these changes precede or develop as a result of the increasing plasma glucose, or whether the increased beta-cell death can be prevented. Early intervention with thiazolidinediones prevents disruption of the islet architecture. To determine the specific effects of rosiglitazone (RSG) on beta-cell mass dynamics, male fa/fa (obese) and +/fa or +/+ (lean) rats age 6 weeks were fed either chow (control group [CN]) or chow mixed with rosiglitazone (RSG group) at a dosage of 10 micromol. kg(-1) body wt.day(-1). Rats were killed after 0, 2, 4, 6, or 10 weeks of treatment (at age 6, 8, 10, 12, or 16 weeks). Plasma glucose increased from 8.9 +/- 0.4 mmol/l at 0 weeks to 34.2 +/- 1.8 mmol/l (P = 0.0001) at 6 weeks of treatment in obese CN rats and fell from 8.0 +/- 0.3 to 6.3 +/- 0.4 mmol/l in obese RSG rats (P = 0.02). beta-cell mass fell by 51% from 2 to 6 weeks of treatment (ages 8-12 weeks) in obese CN rats (6.9 +/- 0.9 to 3.4 +/- 0.5 mg; P < 0.05), whereas beta-cell mass was unchanged in obese RSG rats. At 10 weeks of treatment (age 16 weeks), beta-cell mass in obese CN rats was only 56% of that of obese RSG rats (4.4 +/- 0.4 vs. 7.8 +/- 0.3 mg, respectively; P = 0.0001). The beta-cell replication rate fell from a baseline value of 0.95 +/- 0.12% in lean rats and 0.94 +/- 0.07% in obese rats (at 0 weeks) to approximately 0.3-0.5% in all groups by 6 weeks of treatment (age 12 weeks). After 10 weeks of treatment, beta-cell replication was higher in obese RSG rats than in CN rats (0.59 +/- 0.14 vs. 0.28 +/- 0.05%, respectively; P < 0.02). Application of our mass balance model of beta-cell turnover indicated that net beta-cell death was fivefold higher in obese CN rats as compared with RSG rats after 6 weeks of treatment (age 12 weeks). The increase in beta-cell death in obese CN rats during the 6-week observation period was well correlated with the increase in plasma glucose (r2 = 0.90, P < 0.0001). These results suggest that the development of hyperglycemia in ZDF rats is concomitant with increasing net beta-cell death. beta-cell proliferation compensates for the increased beta-cell loss at a time when plasma glucose is moderately elevated, but compensation ultimately fails and the plasma glucose levels increase beyond approximately 20 mmol/l. Treatment with rosiglitazone, previously shown to reduce insulin resistance, prevents the loss of beta-cell mass in obese ZDF rats by maintaining beta-cell proliferation and preventing increased net beta-cell death. [ABSTRACT FROM AUTHOR]
- Published
- 2001
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29. Breeding strategies for atemoya and cherimoya
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George, A. P., Broadley, R. H., Robert Nissen, Hamill, S. D., and Topp, B. L.
30. 357
- Author
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Lamb, D. R., primary, Schaal, S. F., additional, Binkley, P. F., additional, Copelan, J. Falko, additional, Stevenson, J. S., additional, Williams, N. I., additional, Topp, B., additional, and Brodowicz, G. R., additional
- Published
- 1987
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31. Analysis of phylogenetic relationships in Macadamia shows evidence of extensive reticulate evolution.
- Author
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Manatunga SL, Furtado A, Topp B, Alam M, Mason PJ, Kharabian-Masouleh A, and Henry RJ
- Abstract
The genus Macadamia in the Proteaceae family includes four species native to Australia. Two of the four species, M. integrifolia and M. tetraphylla , have recently been utilized to generate domesticated macadamia varieties, grown for their edible nuts. To explore diversity in macadamia genetic resources, a total of 166 wild genotypes, representing all four species, were sequenced. The four species were clearly distinguished as four separate clades in a phylogenetic analysis of the nuclear genome (based upon concatenated nuclear gene CDS and SNPs). The two larger species ( M. integrifolia and M. tetraphylla ) formed a clade, that had diverged from a clade including the smaller species ( M. ternifolia and M. jansenii ). The greatest diversity in nuclear and chloroplast genomes was found in the more widely distributed M. integrifolia while the rare M. jansenii showed little diversity. The chloroplast phylogeny revealed a much more complex evolutionary history. Multiple chloroplast capture events have resulted in chloroplast genome clades, including genotypes from different species. This suggests extensive reticulate evolution in Macadamia despite the emergence of the four distinct species that are supported by the analysis of their nuclear genomes. The chloroplast genomes showed strong associations with geographical distribution reflecting limited maternal gene movement in these species that have large seeds. The nuclear genomes showed lesser geographical differences, probably reflecting the longer distance pollen movement. This improved understanding of the distribution of diversity in Macadamia will aid in the conservation of these rare species now found in highly fragmented rainforest remnants., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Manatunga, Furtado, Topp, Alam, Mason, Kharabian-Masouleh and Henry.)
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- 2024
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32. Storage Effects on the Physicochemical Properties, Phytochemical Composition, and Sugars in Red-Fleshed Cultivars, 'Rubycot' Plumcot, and 'Queen Garnet' Plum.
- Author
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Kodagoda GK, Hong HT, O'Hare TJ, Topp B, Sultanbawa Y, and Netzel ME
- Subjects
- Food Storage, Phenols analysis, Phenols chemistry, Prunus domestica chemistry, Temperature, Carotenoids analysis, Carotenoids chemistry, Chemical Phenomena, Quercetin analysis, Quercetin chemistry, Phytochemicals chemistry, Phytochemicals analysis, Fruit chemistry, Anthocyanins analysis, Anthocyanins chemistry, Sugars analysis
- Abstract
Domestic storage conditions can have a significant impact on the composition of phytochemicals and sugars in stone fruits. This study aimed to evaluate the effect of two domestic storage temperatures (4 and 23 °C) on the physicochemical properties, phytochemical composition, and sugars of 'Rubycot' (RC) plumcot, a novel stone fruit variety, and 'Queen Garnet' (QG) plum. Initially, RC had a lower total anthocyanin concentration (TAC) than QG, but TAC in RC increased significantly ( p < 0.05) during storage, peaking at +95% after 7 days at 23 °C, while QG reached +60% after 14 days. At 4 °C, TAC increased for both varieties (RC +30%, QG +27%). RC had a higher initial total phenolic content (TPC), which also increased for both fruits. QG had a significantly higher initial total quercetin concentration (TQC), increasing by 40% ( p < 0.05) at 23 °C. The initial total carotenoid concentration in QG was higher than that in RC, but after 10 days at 23 °C, RC had a higher carotenoid concentration than QG. Both varieties showed similar sugar profiles, with QG starting higher but decreasing over time at both storage temperatures. Results from this study showed that ambient storage significantly increases total anthocyanins, total quercetins, and TPC in RC and QG. However, it is important to evaluate the textural and sensory properties of stored RC and QG in terms of consumer acceptability of the stored fruits.
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- 2024
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33. A bootstrapping method to optimize go/no-go decisions from single-arm, signal-finding studies in oncology.
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Dutta R, Mohan A, Buros-Novik J, Goldmacher G, Akala OO, and Topp B
- Subjects
- Humans, ROC Curve, Computer Simulation, Models, Theoretical, Antineoplastic Agents therapeutic use, Antineoplastic Agents administration & dosage, Immune Checkpoint Inhibitors therapeutic use, Immune Checkpoint Inhibitors administration & dosage, Research Design, Clinical Trials, Phase I as Topic methods, Neoplasms drug therapy
- Abstract
Phase Ib trials are common in oncology development but often are not powered for statistical significance. Go/no-go decisions are largely driven by observed trends in response data. We applied a bootstrapping method to systematically compare tumor dynamic end points to historical control data to identify drugs with clinically meaningful efficacy. A proprietary mathematical model calibrated to phase Ib anti-PD-1 therapy trial data (KEYNOTE-001) was used to simulate thousands of phase Ib trials (n = 30) with a combination of anti-PD-1 therapy and four novel agents with varying efficacy. A redacted bootstrapping method compared these results to a simulated phase III control arm (N = 511) while adjusting for differences in trial duration and cohort size to determine the probability that the novel agent provides clinically meaningful efficacy. Receiver operating characteristic (ROC) analysis showed strong ability to separate drugs with modest (area under ROC [AUROC] = 83%), moderate (AUROC = 96%), and considerable efficacy (AUROC = 99%) from placebo in early-phase trials (n = 30). The method was shown to effectively move drugs with a range of efficacy through an in silico pipeline with an overall success rate of 93% and false-positive rate of 7.5% from phase I to phase III. This model allows for effective comparisons of tumor dynamics from early clinical trials with more mature historical control data and provides a framework to predict drug efficacy in early-phase trials. We suggest this method should be employed to improve decision making in early oncology trials., (© 2024 Merck Sharp & Dohme LLC and The Author(s). CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
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- 2024
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34. Biomarker development for PD-(L)1 axis inhibition: a consensus view from the SITC Biomarkers Committee.
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Monette A, Warren S, Barrett JC, Garnett-Benson C, Schalper KA, Taube JM, Topp B, and Snyder A
- Subjects
- Humans, Neoplasms drug therapy, Neoplasms metabolism, B7-H1 Antigen antagonists & inhibitors, B7-H1 Antigen metabolism, Immune Checkpoint Inhibitors therapeutic use, Immune Checkpoint Inhibitors pharmacology, Immunotherapy methods, Consensus, Biomarkers, Tumor metabolism
- Abstract
Therapies targeting the programmed cell death protein-1/programmed death-ligand 1 (PD-L1) (abbreviated as PD-(L)1) axis are a significant advancement in the treatment of many tumor types. However, many patients receiving these agents fail to respond or have an initial response followed by cancer progression. For these patients, while subsequent immunotherapies that either target a different axis of immune biology or non-immune combination therapies are reasonable treatment options, the lack of predictive biomarkers to follow-on agents is impeding progress in the field. This review summarizes the current knowledge of mechanisms driving resistance to PD-(L)1 therapies, the state of biomarker development along this axis, and inherent challenges in future biomarker development for these immunotherapies. Innovation in the development and application of novel biomarkers and patient selection strategies for PD-(L)1 agents is required to accelerate the delivery of effective treatments to the patients most likely to respond., Competing Interests: Competing interests: SW—Salary and employment: Kite Pharma, Gilead; Consulting fees: SciSpot; Stock ownership: Kite Pharma, Gilead. JCB—Salary and employment: Precede Biosciences; Ownership: JCarl Consulting, LLC; Stock Ownership: AstraZeneca. CG-B—Salary and employment: Bristol Myers Squibb. Stock ownership: Bristol Myers Squibb. KAS—Consulting fees: Shattuck Labs, EMD Serono, Clinica Alemana de Santiago, Genmab, Takeda, Merck Sharpe & Dohme, Bristol Myers Squibb, AstraZeneca, Agenus, Repertoire; Fees for non-CE services: Bristol Myers Squibb, Fluidigm Corporation, Genmab, Merck, Takeda; Contracted research: Navigate Biopharma, Tesaro/GSK, Moderna Inc., Pierre-Fabre, Takeda, Surface Oncology, Merck Sharpe & Dohme, Bristol Myers Squibb, AstraZeneca, Ribon Therapeutics, Akoya Biosciences, Boehringer-Ingelheim, Eli Lilly. JMT—Research funding: Bristol Myers Squibb, Akoya Biosciences; Consulting fees: Bristol Myers Squibb, Roche/Genentech, Merck & Co., AstraZeneca, Regeneron; Stock ownership: Akoya Biosciences. BT—Salary and employment: Merck & Co.; Stock ownership: Merck & Co. AS—Salary and employment: Generate Biomedicines; Stock ownership, Generate Biomedicines, Merck & Co., Allogene. AM—Nothing to disclose. SITC Staff: FD, PJI—Nothing to disclose., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2024
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35. RECISTv1.1 progression in oncology: Shades of gray.
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Topp B, Snyder A, and Wolchok J
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- Humans, Treatment Outcome, Response Evaluation Criteria in Solid Tumors, Progression-Free Survival, Medical Oncology, Neoplasms drug therapy
- Abstract
The Response Evaluation Criteria in Solid Tumors (RECIST)-based outcomes, such as objective response rate (ORR) or progression free survival (PFS), are standard outcomes for early oncology trials. These indices provide a black-and-white interpretation of response to therapy. We propose that lesion-level analysis and mechanism-based pharmacodynamic endpoints may provide a more informative index of response to therapy. Accounting for "shades of gray" in lesion-level response assessments may reduce bias in go/no-go decisions and biomarker analyses for novel oncology compounds and discontinuation decisions for individual patients., Competing Interests: Declaration of interests B.T. is an employee of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, US. A.S. is an employee of Generate Biomedicine and owns stock in Merck. J.W. is a consultant for Apricity; Ascentage Pharma; AstraZeneca; BeiGene; Bicara Therapeutics; Bristol Myers Squibb; Chugai, Daiichi Sankyo; Dragonfly; Imvaq; Larkspur; Psioxus, Tizona; and Trishula Therapeutics. J.W. received grant/research support from Bristol Myers Squibb and Sephora. J.W. has equity in Apricity, Arsenal IO; Ascentage; CellCarta; Imvaq; Linneaus, Larkspur; Georgiamune; Maverick; Tizona Therapeutics; and Xenimmune., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2023
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36. Incorporating lesion-to-lesion heterogeneity into early oncology decision making.
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Kumar R, Qi T, Cao Y, and Topp B
- Subjects
- Humans, Medical Oncology, Treatment Outcome, Response Evaluation Criteria in Solid Tumors, Decision Making, Neoplasms drug therapy
- Abstract
RECISTv1.1 (Response Evaluation Criteria In Solid Tumors) is the most commonly used response grading criteria in early oncology trials. In this perspective, we argue that RECISTv1.1 is ambiguous regarding lesion-to-lesion variation that can introduce bias in decision making. We show theoretical examples of how lesion-to-lesion variability causes bias in RECISTv1.1, leading to misclassification of patient response. Next, we review immune checkpoint inhibitor (ICI) clinical trial data and find that lesion-to-lesion heterogeneity is widespread in ICI-treated patients. We illustrate the implications of ignoring lesion-to-lesion heterogeneity in interpreting biomarker data, selecting treatments for patients with progressive disease, and go/no-go decisions in drug development. Further, we propose that Quantitative Systems Pharmacology (QSP) models can aid in developing better metrics of patient response and treatment efficacy by capturing patient responses robustly by considering lesion-to-lesion heterogeneity. Overall, we believe patient response evaluation with an appreciation of lesion-to-lesion heterogeneity can potentially improve decision-making at the early stage of oncology drug development and benefit patient care., Competing Interests: Author BT reports employment at the company Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, United States, and is a shareholder in Merck & Co., Inc., Kenilworth, NJ, United States. Author RK was employed by the company Vantage Research Inc. Vantage Research was engaged by MSD as a Contract Research Organization. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Kumar, Qi, Cao and Topp.)
- Published
- 2023
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37. De novo chromosome level assembly of a plant genome from long read sequence data.
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Sharma P, Masouleh AK, Topp B, Furtado A, and Henry RJ
- Subjects
- High-Throughput Nucleotide Sequencing, Sequence Analysis, DNA, Chromosomes, Plant, Genome, Plant, Macadamia genetics
- Abstract
Recent advances in the sequencing and assembly of plant genomes have allowed the generation of genomes with increasing contiguity and sequence accuracy. Chromosome level genome assemblies using sequence contigs generated from long read sequencing have involved the use of proximity analysis (Hi-C) or traditional genetic maps to guide the placement of sequence contigs within chromosomes. The development of highly accurate long reads by repeated sequencing of circularized DNA (HiFi; PacBio) has greatly increased the size of contigs. We now report the use of HiFiasm to assemble the genome of Macadamia jansenii, a genome that has been used as a model to test sequencing and assembly. This achieved almost complete chromosome level assembly from the sequence data alone without the need for higher level chromosome map information. Eight of the 14 chromosomes were represented by a single large contig (six with telomere repeats at both ends) and the other six assembled from two to four main contigs. The small number of chromosome breaks appears to be the result of highly repetitive regions including ribosomal genes that cannot be assembled by these approaches. De novo assembly of near complete chromosome level plant genomes now appears possible using these sequencing and assembly tools. Further targeted strategies might allow these remaining gaps to be closed., (© 2021 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)
- Published
- 2022
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38. Discovery of Single Nucleotide Polymorphisms for Resistance to Abnormal Vertical Growth in Macadamia.
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Zakeel MCM, Alam M, Geering ADW, Topp B, and Akinsanmi OA
- Abstract
Abnormal vertical growth (AVG) syndrome is a serious threat to the Australian macadamia industry as it decreases the yield of nuts by as much as 70% per annum. A lack of information on the cause of AVG has hindered the development of an effective disease management strategy. Discovery of genetic markers associated with disease resistance can be used as tool for rapid selection of elite cultivars, hence helps in efficient disease management. Differences in field susceptibility of macadamia cultivars provide an opportunity for discovery of genetic markers that are associated with host resistance. REML mixed model analysis was performed to estimate the AVG rating of 51 cultivars from multiple origins using phenotypic data from 359 trees planted in four sites. Most of the Hawaiian cultivars were found as susceptible, while selections from the Australian macadamia industry breeding program were predominantly resistant. All the cultivars were genotyped for 13,221 DArTseq-based single nucleotide polymorphism (SNP) markers. A bulked sample analysis was performed using 20 genotypes each at the extremes of AVG phenotypic ratings. Ten SNP markers were predicted to be associated with AVG resistance and two arbitrarily selected SNP markers were validated using PCR and Sanger sequencing. Our findings suggest that AVG resistance in the commercial cultivars may be derived from the genomic introgression of Macadamia tetraphylla through interspecific hybridization. The results may support marker-assisted selection for macadamia germplasm with AVG resistance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zakeel, Alam, Geering, Topp and Akinsanmi.)
- Published
- 2021
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39. The genome of the endangered Macadamia jansenii displays little diversity but represents an important genetic resource for plant breeding.
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Sharma P, Murigneux V, Haimovitz J, Nock CJ, Tian W, Kharabian Masouleh A, Topp B, Alam M, Furtado A, and Henry RJ
- Abstract
Macadamia, a recently domesticated expanding nut crop in the tropical and subtropical regions of the world, is one of the most economically important genera in the diverse and widely adapted Proteaceae family. All four species of Macadamia are rare in the wild with the most recently discovered, M. jansenii , being endangered. The M. jansenii genome has been used as a model for testing sequencing methods using a wide range of long read sequencing techniques. Here, we report a chromosome level genome assembly, generated using a combination of Pacific Biosciences sequencing and Hi-C, comprising 14 pseudo-molecules, with a N50 of 52 Mb and a total genome assembly size of 758 Mb of which 56% is repetitive. Completeness assessment revealed that the assembly covered -97.1% of the conserved single copy genes. Annotation predicted 31,591 protein coding genes and allowed the characterization of genes encoding biosynthesis of cyanogenic glycosides, fatty acid metabolism, and anti-microbial proteins. Re-sequencing of seven other genotypes confirmed low diversity and low heterozygosity within this endangered species. Important morphological characteristics of this species such as small tree size and high kernel recovery suggest that M. jansenii is an important source of these commercial traits for breeding. As a member of a small group of families that are sister to the core eudicots, this high-quality genome also provides a key resource for evolutionary and comparative genomics studies., Competing Interests: The Authors did not report any conflict of interest., (© 2021 The Authors. Plant Direct published by American Society of Plant Biologists and the Society for Experimental Biology and John Wiley & Sons Ltd.)
- Published
- 2021
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40. Lesion-level heterogeneity of radiologic progression in patients treated with pembrolizumab.
- Author
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Topp BG, Thiagarajan K, De Alwis DP, Snyder A, and Hellmann MD
- Subjects
- Antibodies, Monoclonal, Humanized, Humans, Retrospective Studies, Carcinoma, Non-Small-Cell Lung diagnostic imaging, Carcinoma, Non-Small-Cell Lung drug therapy, Lung Neoplasms diagnostic imaging, Lung Neoplasms drug therapy
- Abstract
Background: Disease progression is often considered a binary state reflecting presence or absence of response. Meaningful heterogeneity between metastatic sites of a given patient may exist, however, and may impact therapeutic outcomes. To characterize the heterogeneity of progression with immunotherapy, we evaluated lesion-level dynamics of pembrolizumab-treated patients across three tumor types., Patients and Methods: Individual metastatic lesion dynamics were analyzed retrospectively in patients with advanced melanoma, non-small-cell lung cancer (NSCLC), and gastric or gastroesophageal junction (G/GEJ) cancer who received pembrolizumab in KEYNOTE-001 or KEYNOTE-059. Primary progression was defined as radiologic progression as per RECIST v1.1 occurring at the first on-treatment study scan (∼9-12 weeks, +2-week window) and secondary progression as progression occurring beyond the first scan (∼14 weeks and beyond). The change in sum of target lesions and of individual lesions was examined, as were patterns and timing of progression., Results: 9239 individual lesions from 1194 patients were analyzed. Among patients with primary progression [39% (200/511) of patients with melanoma, 41% (179/432) with NSCLC, 61% (154/251) with G/GEJ cancer], most patients (51%-63%) had a mixture of growing, stable, and shrinking lesions. Despite overall primary progression, a minority of patients (19%-25%) had tumor growth at every metastatic site and 17%-32% had ≥1 shrinking lesion. Among patients with secondary progression [22% (113/511) of patients with melanoma, 27% (117/432) with NSCLC, 18% (44/251) with G/GEJ cancer], few patients had rebound growth (>20% increase in diameter from nadir) in all lesions whereas the majority (74%-84%) had sustained regression in ≥1 lesion., Conclusions: Lesion-level heterogeneity at the time of disease progression was common in pembrolizumab-treated patients, with many patients demonstrating ongoing disease control in a subset of tumor sites. These results may inform clinical decision-making, trial design, and tumor sampling in the future., Competing Interests: Disclosure BGT reports employment at Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA, and is a shareholder in Merck & Co., Inc., Kenilworth, NJ, USA. KT has declared no conflicts of interest. DPDA reports employment at Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA, and is a shareholder in Merck & Co., Inc., Kenilworth, NJ, USA. AS reports employment at Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA, and is a shareholder in Merck & Co., Inc., Kenilworth, NJ, USA. MDH reports grants from Bristol Myers Squibb; nonfinancial support from AstraZeneca and Bristol Myers Squibb; and personal fees from Achilles; Arcus AstraZeneca; Blueprint Medicines; Bristol Myers Squibb; Genentech/Roche; Immunai; Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA; Mirati; Nektar; Pact Pharma; Shattuck Labs; Syndax; Janssen; and Regeneron; as well as equity options from Immunai, Shattuck Labs, and Arcus. A patent filed by Memorial Sloan Kettering related to the use of tumor mutational burden to predict response to immunotherapy (PCT/US2015/062208) is pending and licensed by PGDx., (Copyright © 2021 Merck Sharp & Dohme Corp., The Author(s). Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2021
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41. Semi-Mechanistic Model for the Antitumor Response of a Combination Cocktail of Immuno-Modulators in Non-Inflamed (Cold) Tumors.
- Author
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Sancho-Araiz A, Zalba S, Garrido MJ, Berraondo P, Topp B, de Alwis D, Parra-Guillen ZP, Mangas-Sanjuan V, and Trocóniz IF
- Abstract
Immune checkpoint inhibitors, administered as single agents, have demonstrated clinical efficacy. However, when treating cold tumors, different combination strategies are needed. This work aims to develop a semi-mechanistic model describing the antitumor efficacy of immunotherapy combinations in cold tumors. Tumor size of mice treated with TC-1/A9 non-inflamed tumors and the drug effects of an antigen, a toll-like receptor-3 agonist (PIC), and an immune checkpoint inhibitor (anti-programmed cell death 1 antibody) were modeled using Monolix and following a middle-out strategy. Tumor growth was best characterized by an exponential model with an estimated initial tumor size of 19.5 mm
3 and a doubling time of 3.6 days. In the treatment groups, contrary to the lack of response observed in monotherapy, combinations including the antigen were able to induce an antitumor response. The final model successfully captured the 23% increase in the probability of cure from bi-therapy to triple-therapy. Moreover, our work supports that CD8+ T lymphocytes and resistance mechanisms are strongly related to the clinical outcome. The activation of antigen-presenting cells might be needed to achieve an antitumor response in reduced immunogenic tumors when combined with other immunotherapies. These models can be used as a platform to evaluate different immuno-oncology combinations in preclinical and clinical scenarios.- Published
- 2021
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42. Beyond the single average tumor: Understanding IO combinations using a clinical QSP model that incorporates heterogeneity in patient response.
- Author
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Kumar R, Thiagarajan K, Jagannathan L, Liu L, Mayawala K, de Alwis D, and Topp B
- Subjects
- Antibodies, Monoclonal, Humanized administration & dosage, Antineoplastic Combined Chemotherapy Protocols administration & dosage, Computer Simulation, Disease Progression, Humans, Ipilimumab administration & dosage, Melanoma immunology, Melanoma pathology, Network Pharmacology, Antineoplastic Combined Chemotherapy Protocols pharmacology, Melanoma drug therapy, Models, Biological
- Abstract
A quantitative systems pharmacology model for metastatic melanoma was developed for immuno-oncology with the goal of predicting efficacy of combination checkpoint therapy with pembrolizumab and ipilimumab. This literature-based model is developed at multiple scales: (i) tumor and immune cell interactions at a lesion level; (ii) multiple heterogeneous target lesions, nontarget lesion growth, and appearance of new metastatic lesion at a patient level; and (iii) interpatient differences at a population level. The model was calibrated to pembrolizumab and ipilimumab monotherapy in patients with melanoma from Robert et al., specifically, waterfall plot showing target lesion response and overall response rate (Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1), which additionally considers nontarget lesion growth and appearance of new metastatic lesions. We then used the model to predict waterfall and RECIST version 1.1 for combination treatment reported in Long et al. A key insight from this work was that nontarget lesions growth and appearance of new metastatic lesion contributed significantly to disease progression, despite reduction in target lesions. Further, the lesion level simulations of combination therapy show substantial efficacy in warm lesions (intermediary immunogenicity) but limited advantage of combination in both cold and hot lesions (low and high immunogenicity). Because many patients with metastatic disease are expected to have a mixture of these lesions, disease progression in such patients may be driven by a subset of cold lesions that are unresponsive to checkpoint inhibitors. These patients may benefit more from the combinations which include therapies to target cold lesions than double checkpoint inhibitors., (© 2021 Merck Sharp & Dohme Corporation & Vantage Research LLC. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2021
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43. Improvements in the sequencing and assembly of plant genomes.
- Author
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Sharma P, Al-Dossary O, Alsubaie B, Al-Mssallem I, Nath O, Mitter N, Rodrigues Alves Margarido G, Topp B, Murigneux V, Kharabian Masouleh A, Furtado A, and Henry RJ
- Abstract
Advances in DNA sequencing have made it easier to sequence and assemble plant genomes. Here, we extend an earlier study, and compare recent methods for long read sequencing and assembly. Updated Oxford Nanopore Technology software improved assemblies. Using more accurate sequences produced by repeated sequencing of the same molecule (Pacific Biosciences HiFi) resulted in less fragmented assembly of sequencing reads. Using data for increased genome coverage resulted in longer contigs, but reduced total assembly length and improved genome completeness. The original model species, Macadamia jansenii , was also compared with three other Macadamia species, as well as avocado ( Persea americana ) and jojoba ( Simmondsia chinensis ). In these angiosperms, increasing sequence data volumes caused a linear increase in contig size, decreased assembly length and further improved already high completeness. Differences in genome size and sequence complexity influenced the success of assembly. Advances in long read sequencing technology continue to improve plant genome sequencing and assembly. However, results were improved by greater genome coverage, with the amount needed to achieve a particular level of assembly being species dependent., Competing Interests: The authors declare that they have no competing interests., (© The Author(s) 2021.)
- Published
- 2021
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44. Modulation of intratumoural myeloid cells, the hallmark of the anti-tumour efficacy induced by a triple combination: tumour-associated peptide, TLR-3 ligand and α-PD-1.
- Author
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Zalba S, Belsúe V, Topp B, de Alwis D, Alvarez M, Trocóniz IF, Berraondo P, and Garrido MJ
- Subjects
- Animals, Cell Proliferation, Drug Combinations, Female, Humans, Ligands, Lymphocytes, Tumor-Infiltrating immunology, Mice, Mice, Inbred C57BL, Myeloid Cells drug effects, Myeloid Cells metabolism, Myeloid Cells pathology, Neoplasms drug therapy, Neoplasms metabolism, Neoplasms pathology, Tumor Cells, Cultured, Tumor Microenvironment immunology, Xenograft Model Antitumor Assays, Antibodies, Monoclonal pharmacology, Myeloid Cells immunology, Neoplasms immunology, Peptide Fragments pharmacology, Programmed Cell Death 1 Receptor antagonists & inhibitors, Toll-Like Receptor 3 metabolism
- Abstract
Background: Anti-programmed cell death 1 (PD-1)/programmed death-ligand 1 (PD-L1) monoclonal antibodies (mAbs) show remarkable clinical anti-tumour efficacy. However, rational combinations are needed to extend the clinical benefit to primary resistant tumours. The design of such combinations requires the identification of the kinetics of critical immune cell populations in the tumour microenvironment., Methods: In this study, we compared the kinetics of immune cells in the tumour microenvironment upon treatment with immunotherapy combinations with different anti-tumour efficacies in the non-inflamed tumour model TC-1/A9. Tumour-bearing C57BL/6J mice were treated with all possible combinations of a human papillomavirus (HPV) E7 long peptide, polyinosinic-polycytidylic acid (PIC) and anti-PD-1 mAb. Tumour growth and kinetics of the relevant immune cell populations were assessed over time. The involvement of key immune cells was confirmed by depletion with mAbs and immunophenotyping with multiparametric flow cytometry., Results: The maximum anti-tumour efficacy was achieved after intratumoural administration of HPV E7 long peptide and PIC combined with the systemic administration of anti-PD-1 mAb. The intratumoural immune cell kinetics of this combination was characterised by a biphasic immune response. An initial upsurge of proinflammatory myeloid cells led to a further rise in effector CD8
+ T lymphocytes at day 8. Depletion of either myeloid cells or CD8+ T lymphocytes diminished the anti-tumour efficacy of the combination., Conclusions: The anti-tumour efficacy of a successful immunotherapy combination in a non-inflamed tumour model relies on an early inflammatory process that remodels the myeloid cell compartment.- Published
- 2021
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45. Effect of Storage on the Nutritional Quality of Queen Garnet Plum.
- Author
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Kodagoda G, Hong HT, O'Hare TJ, Sultanbawa Y, Topp B, and Netzel ME
- Abstract
Due to high perishability, plums are harvested at an early stage of maturity to extend postharvest storage life. Storage time and temperature can significantly affect the phytochemical and sugar composition of plums, altering their palatability and nutritional quality. In this study, variations in physiochemical properties (total soluble solids (TSS), titratable acidity (TA), color (chroma and hue angle)), phytochemical composition (total phenolic content (TPC), total anthocyanin content (TAC), and carotenoids), and sugars in three different tissues of the Queen Garnet plum (QGP) during storage at two common domestic storage temperatures (4 and 23 °C) were evaluated. There was an increase ( p > 0.05) in TSS and a reduction ( p < 0.05) in TA of the outer flesh at 23 °C. Chroma values of all the tissues reduced ( p < 0.05) at 23 °C. At 4 °C, chroma values fluctuated between storage days. The TAC of the peel was the highest ( p < 0.05) among the different tissues and continued to increase up to 10 days of storage at 23 °C (3-fold increase). At 4 °C, the highest ( p < 0.05) TAC (peel) was observed after 14 days of storage (1.2-fold increase). TPC showed similar results. The highest ( p < 0.05) TPC was recorded in the peel after 10 days of storage at 23 °C (2.3-fold increase) and after 14 days of storage at 4 °C (1.3-fold increase), respectively. Total carotenoids in the flesh samples at both storage temperatures were reduced ( p < 0.05) after 14 days. Total sugars also decreased during storage. The results of the present study clearly showed that common domestic storage conditions can improve the nutritional quality of plums by increasing the content of bioactive anthocyanins and other phenolic compounds. However, the increase in phytochemicals needs to be counterbalanced with the decrease in total sugars and TA potentially affecting the sensory attributes of the plums.
- Published
- 2021
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46. Comparison of long-read methods for sequencing and assembly of a plant genome.
- Author
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Murigneux V, Rai SK, Furtado A, Bruxner TJC, Tian W, Harliwong I, Wei H, Yang B, Ye Q, Anderson E, Mao Q, Drmanac R, Wang O, Peters BA, Xu M, Wu P, Topp B, Coin LJM, and Henry RJ
- Subjects
- Genome, Plant, Sequence Analysis, DNA, Software, Genome, Bacterial, High-Throughput Nucleotide Sequencing
- Abstract
Background: Sequencing technologies have advanced to the point where it is possible to generate high-accuracy, haplotype-resolved, chromosome-scale assemblies. Several long-read sequencing technologies are available, and a growing number of algorithms have been developed to assemble the reads generated by those technologies. When starting a new genome project, it is therefore challenging to select the most cost-effective sequencing technology, as well as the most appropriate software for assembly and polishing. It is thus important to benchmark different approaches applied to the same sample., Results: Here, we report a comparison of 3 long-read sequencing technologies applied to the de novo assembly of a plant genome, Macadamia jansenii. We have generated sequencing data using Pacific Biosciences (Sequel I), Oxford Nanopore Technologies (PromethION), and BGI (single-tube Long Fragment Read) technologies for the same sample. Several assemblers were benchmarked in the assembly of Pacific Biosciences and Nanopore reads. Results obtained from combining long-read technologies or short-read and long-read technologies are also presented. The assemblies were compared for contiguity, base accuracy, and completeness, as well as sequencing costs and DNA material requirements., Conclusions: The 3 long-read technologies produced highly contiguous and complete genome assemblies of M. jansenii. At the time of sequencing, the cost associated with each method was significantly different, but continuous improvements in technologies have resulted in greater accuracy, increased throughput, and reduced costs. We propose updating this comparison regularly with reports on significant iterations of the sequencing technologies., (© The Author(s) 2020. Published by Oxford University Press GigaScience.)
- Published
- 2020
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47. Chromosome-Scale Assembly and Annotation of the Macadamia Genome ( Macadamia integrifolia HAES 741).
- Author
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Nock CJ, Baten A, Mauleon R, Langdon KS, Topp B, Hardner C, Furtado A, Henry RJ, and King GJ
- Subjects
- Australia, Chromosomes, Genome, Molecular Sequence Annotation, Macadamia genetics, Plant Breeding
- Abstract
Macadamia integrifolia is a representative of the large basal eudicot family Proteaceae and the main progenitor species of the Australian native nut crop macadamia. Since its commercialisation in Hawaii fewer than 100 years ago, global production has expanded rapidly. However, genomic resources are limited in comparison to other horticultural crops. The first draft assembly of M. integrifolia had good coverage of the functional gene space but its high fragmentation has restricted its use in comparative genomics and association studies. Here we have generated an improved assembly of cultivar HAES 741 (4,094 scaffolds, 745 Mb, N50 413 kb) using a combination of Illumina paired and PacBio long read sequences. Scaffolds were anchored to 14 pseudo-chromosomes using seven genetic linkage maps. This assembly has improved contiguity and coverage, with >120 Gb of additional sequence. Following annotation, 34,274 protein-coding genes were predicted, representing 90% of the expected gene content. Our results indicate that the macadamia genome is repetitive and heterozygous. The total repeat content was 55% and genome-wide heterozygosity, estimated by read mapping, was 0.98% or an average of one SNP per 102 bp. This is the first chromosome-scale genome assembly for macadamia and the Proteaceae. It is expected to be a valuable resource for breeding, gene discovery, conservation and evolutionary genomics., (Copyright © 2020 Nock et al.)
- Published
- 2020
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- View/download PDF
48. Genetic Structure of Wild Germplasm of Macadamia: Species Assignment, Diversity and Phylogeographic Relationships.
- Author
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Mai T, Alam M, Hardner C, Henry R, and Topp B
- Abstract
Macadamia is an Australian native rainforest tree that has been domesticated and traded internationally for its premium nuts. Common cultivars rely upon a limited gene pool that has exploited only two of the four species. Introducing a more diverse germplasm will broaden the genetic base for future crop improvement and better adaptation for changing environments. This study investigated the genetic structure of 302 accessions of wild germplasm using 2872 SNP and 8415 silicoDArT markers. Structure analysis and principal coordinate analysis (PCoA) assigned the 302 accessions into four distinct groups: (i) Macadamia integrifolia , (ii) M. tetraphylla , and (iii) M. jansenii and M. ternifolia , and (iv) admixtures or hybrids. Assignment of the four species matched well with previous characterisations, except for one M. integrifolia and four M. tetraphylla accessions. Using SNP markers, 94 previously unidentified accessions were assigned into the four distinct groups. Finally, 287 accessions were identified as pure examples of one of the four species and 15 as hybrids of M. integrifolia and M. tetraphylla . The admixed accessions showed the highest genetic diversity followed by M. integrifolia , while M. ternifolia and M. jansenii accessions were the least diverse. Mantel test analysis showed a significant correlation between genetic and geographic distance for M. integrifolia (r = 0.51, p = 0.05) and a positive but not significant correlation for M. tetraphylla (r = 0.45, p = 0.06). This study provides a population genetics overview of macadamia germplasm as a background for a conservation strategy and provides directions for future macadamia breeding.
- Published
- 2020
- Full Text
- View/download PDF
49. Genome-wide association studies for yield component traits in a macadamia breeding population.
- Author
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O'Connor K, Hayes B, Hardner C, Nock C, Baten A, Alam M, Henry R, and Topp B
- Subjects
- Computational Biology, Genome-Wide Association Study, Genotyping Techniques, Macadamia genetics, Phenotype, Plant Breeding, Plant Proteins genetics, Macadamia growth & development, Polymorphism, Single Nucleotide, Quantitative Trait Loci
- Abstract
Background: Breeding for new macadamia cultivars with high nut yield is expensive in terms of time, labour and cost. Most trees set nuts after four to five years, and candidate varieties for breeding are evaluated for at least eight years for various traits. Genome-wide association studies (GWAS) are promising methods to reduce evaluation and selection cycles by identifying genetic markers linked with key traits, potentially enabling early selection through marker-assisted selection. This study used 295 progeny from 32 full-sib families and 29 parents (18 phenotyped) which were planted across four sites, with each tree genotyped for 4113 SNPs. ASReml-R was used to perform association analyses with linear mixed models including a genomic relationship matrix to account for population structure. Traits investigated were: nut weight (NW), kernel weight (KW), kernel recovery (KR), percentage of whole kernels (WK), tree trunk circumference (TC), percentage of racemes that survived from flowering through to nut set, and number of nuts per raceme., Results: Seven SNPs were significantly associated with NW (at a genome-wide false discovery rate of < 0.05), and four with WK. Multiple regression, as well as mapping of markers to genome assembly scaffolds suggested that some SNPs were detecting the same QTL. There were 44 significant SNPs identified for TC although multiple regression suggested detection of 16 separate QTLs., Conclusions: These findings have important implications for macadamia breeding, and highlight the difficulties of heterozygous populations with rapid LD decay. By coupling validated marker-trait associations detected through GWAS with MAS, genetic gain could be increased by reducing the selection time for economically important nut characteristics. Genomic selection may be a more appropriate method to predict complex traits like tree size and yield.
- Published
- 2020
- Full Text
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50. Applications of Quantitative Systems Pharmacology in Model-Informed Drug Discovery: Perspective on Impact and Opportunities.
- Author
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Bradshaw EL, Spilker ME, Zang R, Bansal L, He H, Jones RDO, Le K, Penney M, Schuck E, Topp B, Tsai A, Xu C, Nijsen MJMA, and Chan JR
- Subjects
- Humans, Models, Biological, Research Design, Drug Discovery methods, Systems Biology methods
- Abstract
Quantitative systems pharmacology (QSP) approaches have been increasingly applied in the pharmaceutical since the landmark white paper published in 2011 by a National Institutes of Health working group brought attention to the discipline. In this perspective, we discuss QSP in the context of other modeling approaches and highlight the impact of QSP across various stages of drug development and therapeutic areas. We discuss challenges to the field as well as future opportunities., (© 2019 Takeda California, Inc CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals, Inc. on behalf of the American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2019
- Full Text
- View/download PDF
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