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Societal Impact Statement Society anticipates a world in which more food and fiber must be produced at warmer temperatures, which, on the contrary, have greater constraints on the use of water and fertilizers. Tree legumes are often the climax vegetation on the semi‐arid and arid lands, covering ~25% of the planet, but the knowledge of their genomes is limited. A draft genome sequence for Prosopis alba, a salt and heat tolerant tree that is able to fix nitrogen under harsh conditions, yields new clues about its adaptations. Its rich genetic and ecological diversity makes Prosopis well‐suited to the investigation of gene functions important to its own greater utilization and/or the improvement of climate resilience of other crops. Summary In arid lands that comprise 41% of the Earth's surface and are growing, tree legumes are often the climax vegetation. Now found in much of arid America, Prosopis alba is a salt‐tolerant nitrogen‐fixing tree native to Argentina. We present a Prosopis alba genome assembly that is 707 Mb in size, comprising of 6087 contigs of up to 2,077,851 bp in length and of ~359.3 Mb (50.8%) being repetitive elements dominated (20.3%) by long terminal repeats (LTR) retrotransposons. Among a total of 57,572 coding sequences (CDS), 42,475 are putative protein coding genes with median length of 2748 bp. The Prosopis alba genome shares the legume‐common tetraploidy (LCT) but has not reduplicated, evolving 3.5% and 23.1% faster than Phaseolus vulgaris and Glycine max, respectively, since the LCT. The 50 most expanded gene families include many that are involved in ion homeostasis, perhaps related to drought and/or salt adaptation, together with photosynthetic genes carbonic anhydrase (CA), malate dehydrogenase (MDH) and malic enzyme and gene families involved in circadian clock systems, synthesis of brassinosteroids, auxin and gibberellin. Some expanded gene families include members showing molecular signatures of positive selection, as do numerous multi‐copy orthologous groups with features associated with pathogen resistance and single‐copy orthogroups related to drought and salt stress response, root and root hair development, nodulation, heavy metal detoxification and stay‐green habit. Coupling genomics‐based clues about possible causes of its striking physiological adaptations with rich diversity in ecological context offers means to further investigate functional roles of specific Prosopis genes/alleles.

Societal Impact Statement: Society anticipates a world in which more food and fiber must be produced at warmer temperatures, which, on the contrary, have greater constraints on the use of water and fertilizers. Tree legumes are often the climax vegetation on the semi‐arid and arid lands, covering ~25% of the planet, but the knowledge of their genomes is limited. A draft genome sequence for Prosopis alba, a salt and heat tolerant tree that is able to fix nitrogen under harsh conditions, yields new clues about its adaptations. Its rich genetic and ecological diversity makes Prosopis well‐suited to the investigation of gene functions important to its own greater utilization and/or the improvement of climate resilience of other crops. Summary: In arid lands that comprise 41% of the Earth's surface and are growing, tree legumes are often the climax vegetation. Now found in much of arid America, Prosopis alba is a salt‐tolerant nitrogen‐fixing tree native to Argentina.We present a Prosopis alba genome assembly that is 707 Mb in size, comprising of 6087 contigs of up to 2,077,851 bp in length and of ~359.3 Mb (50.8%) being repetitive elements dominated (20.3%) by long terminal repeats (LTR) retrotransposons. Among a total of 57,572 coding sequences (CDS), 42,475 are putative protein coding genes with median length of 2748 bp. The Prosopis alba genome shares the legume‐common tetraploidy (LCT) but has not reduplicated, evolving 3.5% and 23.1% faster than Phaseolus vulgaris and Glycine max, respectively, since the LCT.The 50 most expanded gene families include many that are involved in ion homeostasis, perhaps related to drought and/or salt adaptation, together with photosynthetic genes carbonic anhydrase (CA), malate dehydrogenase (MDH) and malic enzyme and gene families involved in circadian clock systems, synthesis of brassinosteroids, auxin and gibberellin. Some expanded gene families include members showing molecular signatures of positive selection, as do numerous multi‐copy orthologous groups with features associated with pathogen resistance and single‐copy orthogroups related to drought and salt stress response, root and root hair development, nodulation, heavy metal detoxification and stay‐green habit.Coupling genomics‐based clues about possible causes of its striking physiological adaptations with rich diversity in ecological context offers means to further investigate functional roles of specific Prosopis genes/alleles. [ABSTRACT FROM AUTHOR]

The recombinant inbred lines of inter-specific cross, Gossypium hirsutum cv. DS-28 × G. barbadense cv. SBYF-425 was evaluated in three consecutive rainy seasons of 2017–18 (F13), 2018–19 (F14) and 2019–20 (F15) in an augmented design. The preponderance of huge continuous variability for both productivity and fiber quality traits was recorded. The principal component analysis revealed that the mapping population was well suited for mapping of productivity and fiber quality traits. On the basis the Z-scores for skewness and kurtosis, 178 RILs with normal distribution were selected for genetic linkage mapping. A high-density saturated linkage map was constructed using SNP arrays of CottonSNP63K, an Illumina's infinium array and CottonSNP50K, CSIR-National Botanical Research Institute's Axiom array with a total spanned length of 2402.65 cM, an average marker density of 1.54 and with map coverage of 96.99% of the reference genome. The developed genetic map of inter specific cross of Indian cotton varieties is a highly saturated in terms of coverage and highly comparable to the published maps. In QTL analysis, altogether 99 QTLs were identified for productivity and fiber quality traits. Among those, eight were stable and 38 were major QTLs. Cluster 1, 4 and 6 respectively on chromosome AD_chr.03, AD_chr.14 and AD_chr.18 were the biggest QTL clusters each with four QTLs and cluster 4 and 6 were QTL hotspots for fiber quality traits. [ABSTRACT FROM AUTHOR]

During the 1961–1971 decade, Sydney Brenner made several significant contributions to molecular biology—showing that the genetic code is a triplet code; discovery of messenger RNA; colinearity of gene and protein; decoding of chain terminating codons; and then an important transition: the development of the nematode Caenorhabditis elegans into the model eucaryote genetic system that has permeated the whole of recent biology. [ABSTRACT FROM AUTHOR]

Brachypodium distachyon (Brachypodium) has been recently recognized as an emerging model system for both comparative and functional genomics in grass species. In this study, 55,221 repeat masked Brachypodium BAC end sequences (BES) were used for comparative analysis against the 12 rice pseudomolecules. The analysis revealed that ~26.4% of BES have significant matches with the rice genome and 82.4% of the matches were homologous to known genes. Further analysis of paired-end BES and ~1.0 Mb sequences from nine selected BACs proved to be useful in revealing conserved regions and regions that have undergone considerable genomic changes. Differential gene amplification, insertions/deletions and inversions appeared to be the common evolutionary events that caused variations of microcolinearity at different orthologous genomic regions. It was found that ~17% of genes in the two genomes are not colinear in the orthologous regions. Analysis of BAC sequences also revealed higher gene density (~9 kb/gene) and lower repeat DNA content (~13.1%) in Brachypodium when compared to the orthologous rice regions, consistent with the smaller size of the Brachypodium genome. The 119 annotated Brachypodium genes were BLASTN compared against the wheat EST database and deletion bin mapped wheat ESTs. About 77% of the genes retrieved significant matches in the EST database, while 9.2% matched to the bin mapped ESTs. In some cases, genes in single Brachypodium BACs matched to multiple ESTs that were mapped to the same deletion bins, suggesting that the Brachypodium genome will be useful for ordering wheat ESTs within the deletion bins and developing specific markers at targeted regions in the wheat genome.

Grain Protein Content (GPC) is an important determinant of grain quality in many crops, including barley and wheat. Recently, the map-based cloning of Gpc-B1, a wheat GPC quantitative trait locus (QTL), revealed a NAC transcription factor (TtNAM-B1) that was associated with increased grain protein, zinc, and iron content. In barley, a QTL for GPC was identified in a segregating population developed from a cross between 'Karl' (low GPC) and 'Lewis' (average GPC). This QTL was mapped near marker hvm74 on chromosome 6H and was suggested as a potential orthologue for Gpc-B1 on chromosome arm 6BS. In the current study, wheat genes that were previously mapped within a 0.8 cM segment spanning the TtNAM-B1 gene were converted into barley molecular markers. These new markers, together with the barley TtNAM-B1 orthologous gene (designated HvNAM-1 hereafter) were mapped on a 0.7 cM interval encompassing the peak of the barley QTL for GPC on chromosome arm 6HS. Sequence comparison of HvNAM-1 parental alleles showed two single nucleotide polymorphisms (SNPs) that result in two amino acid differences. Analysis of the allelic variation in a wild and cultivated barley collection revealed that the Karl haplotype was present only in nine out of 147 tested accessions. The colinearity between the wheat and barley GPC regions and the low frequency of the HvNAM-1 haplotype associated with low GPC suggest that the barley NAC transcription factor is responsible for the GPC QTL on barley chromosome 6H.

Grain protein content (GPC) is important for human nutrition and has a strong influence on pasta and bread quality. A quantitative trait locus, derived from a Triticum turgidum ssp. dicoccoides accession (DIC), with an average increase in GPC of 14 g kg(-1) was mapped on chromosome 6BS. Using the wheat-rice colinearity, a high-density map of the wheat region was developed and the quantitative trait locus was mapped as a simple Mendelian locus designated Gpc-B1. A physical map of approx. 250 kb of the Gpc-B1 region was developed using a tetraploid wheat bacterial artificial chromosome library. The constructed physical map included the two Gpc-B1 flanking markers and one potential candidate gene from the colinear rice region completely linked to Gpc-B1. The relationship between physical and genetic distances and the feasibility of isolating genes by positional cloning in wheat are discussed. A high-throughput codominant marker, Xuhw89, was developed. A 4-bp deletion present in the DIC allele was absent in a collection of 117 cultivated tetraploid and hexaploid wheat germplasm, suggesting that this marker will be useful to incorporate the high GPC allele from the DIC accession studied here into commercial wheat varieties.

The conservation of the linear order (colinearity) of genetic markers along large chromosome segments in wheat and rice is well established, but less is known about the microcolinearity between both genomes at subcentimorgan distances. In this study we focused on the microcolinearity between a 2.6-cM interval flanked by markers Xcdo365 and Xucw65 on wheat chromosome 6B and rice chromosome 2. A previous study has shown that this wheat segment includes the Gpc-6B1 locus, which is responsible for large differences in grain protein content (GPC) and is the target of a positional cloning effort in our laboratories. Twenty-one recombination events between Xcdo365 and Xucw65 were found in a large segregating population (935 gametes) and used to map 17 genes selected from rice chromosome 2 in the wheat genetic map. We found a high level of colinearity between a 2.1-cM region flanked by loci Xucw75 and Xucw67 on wheat chromosome 6B and a 350-kb uninterrupted sequenced region in rice chromosome arm 2S. Colinearity between these two genomes was extended to the region proximal to Xucw67 (eight colinear RFLP markers), but was interrupted distal to Xucw75 (six non-colinear RFLP markers). Analysis of different comparative studies between rice and wheat suggests that microcolinearity is more frequently disrupted in the distal region of the wheat chromosomes. Fortunately, the region encompassing the Gpc-6B1 locus showed an excellent conservation between the two genomes, facilitating the saturation of the target region of the wheat genetic map with molecular markers. These markers were used to map the Gpc-6B1 locus into a 0.3-cM interval flanked by PCR markers Xucw79 and Xucw71, and to identify five candidate genes within the colinear 64-kb region in rice.

Wheat is the largest produced grain crop world-wide and has been extensively studied for a wide range of agronomic traits located across the genome. Its large chromosomes and the capacity of the polyploid genome to tolerate the addition or loss of chromosomes facilitated a fast progress in early wheat genetics using cytogenetic techniques. However, these same characteristics have limited the progress in genomic studies that have been focused on diploid model species with smaller genomes such as rice and Arabidopsis. These model systems are seen as a launching pad for comparative genomic strategies to tackle the challenges associated with the larger genomes of other plants such as wheat. The strengths and limitations of comparative genomic approaches to study the wheat genome are presented in this review. Structural genomic studies in wheat started by the development of large DNA insert libraries (BAC libraries) for the progenitor A and D genomes using diploid species and for the B genome using tetraploid wheat. Sequencing of the first wheat BAC clones has confirmed cytogenetic results indicating the presence of portions of the wheat genome that contain high density gene regions approximating that of the model species. These high-density gene regions also exhibited higher-than-average rates of genetic to physical distances. Functional genomic approaches, focused on the expressed portion of the wheat genome, have recently led to an exponential growth of expressed sequence tagged (EST) databases from both the public and private sector. Assigning gene function to these ESTs is now one of the major challenges in wheat genomics. Hypothesis testing strategies based on high-resolution EST mapping, candidate gene analysis, gene expression profiling, and proteomics are being used as entry points towards assigning gene function. Improving transformation efficiency as well as selection strategies for high throughput mutagenesis experiments will be two critical areas of research for the ultimate assignment of function to the numerous wheat genes that are being discovered using the new genomic tools. © 2001 Éditions scientifiques et médicales Elsevier SAS.

The assembly-line synthases that produce bacterial polyketide natural products follow a modular paradigm in which each round of chain extension is catalysed by a different set or module of enzymes. Examples of deviation from this paradigm, in which a module catalyses either multiple extensions or none are of interest from both a mechanistic and an evolutionary viewpoint. We present evidence that in the biosynthesis of the 36-membered macrocyclic aminopolyol lactones (marginolactones) azalomycin and kanchanamycin, isolated respectively from Streptomyces malaysiensis DSM4137 and Streptomyces olivaceus Tü4018, the first extension module catalyses both the first and second cycles of polyketide chain extension. To confirm the integrity of the azl gene cluster, it was cloned intact on a bacterial artificial chromosome and transplanted into the heterologous host strain Streptomyces lividans, which does not possess the genes for marginolactone production. When furnished with 4-guanidinobutyramide, a specific precursor of the azalomycin starter unit, the recombinant S. lividans produced azalomycin, showing that the polyketide synthase genes in the sequenced cluster are sufficient to accomplish formation of the full-length polyketide chain. This provides strong support for module iteration in the azalomycin and kanchanamycin biosynthetic pathways. In contrast, re-sequencing of the gene cluster for biosynthesis of the polyketide β-lactone ebelactone in Streptomyces aburaviensis has shown that, contrary to a recently-published proposal, the ebelactone polyketide synthase faithfully follows the colinear modular paradigm.

Among the seven tetraploid cotton species, little is known about transmission genetics and genome organization in Gossypium mustelinum, the species most distant from the source of most cultivated cotton, G. hirsutum. In this research, an F2 population was developed from an interspecific cross between G. hirsutum and G. mustelinum (HM). A genetic linkage map was constructed mainly using simple sequence repeat (SSRs) and restriction fragment length polymorphism (RFLP) DNA markers. The arrangements of most genetic loci along the HM chromosomes were identical to those of other tetraploid cotton species. However, both major and minor structural rearrangements were also observed, for which we propose a parsimony-based model for structural divergence of tetraploid cottons from common ancestors. Sequences of mapped markers were used for alignment with the 26 scaffolds of the G. hirsutum draft genome, and showed high consistency. Quantitative trait locus (QTL) mapping of fiber elongation in advanced backcross populations derived from the same parents demonstrated the value of the HM map. The HM map will serve as a valuable resource for QTL mapping and introgression of G. mustelinum alleles into G. hirsutum, and help clarify evolutionary relationships between the tetraploid cotton genomes.

This year marks the 40th anniversary of the discovery by Ed Lewis of the property of collinearity in the bithorax gene complex in Drosophila. This landmark work illustrated the need to understand regulatory mechanisms that coordinate expression of homeotic gene clusters. Through the efforts of many groups, investigation of the Hox gene family has generated many fundamental findings on the roles and regulation of this conserved gene family in development, disease and evolution. This has led to a number of important conceptual advances in gene regulation and evolutionary biology. This article presents some of the history and advances made through studies on Hox gene clusters. [ABSTRACT FROM AUTHOR]

Hox genes are the key regulators of axial regionalization of bilaterian animals. However, their main function is fulfilled differently in the development of animals from different evolutionary branches. Early patterning of the developing embryos by Hox gene expression in the representatives of protostomes (arthropods, mollusks) starts in the ectodermal cells. On the contrary, the instructive role of the mesoderm in the axial patterning was demonstrated for vertebrates. This makes it difficult to understand if during the axial regionalization of ancestral bilaterians Hox genes first expressed in the developing mesoderm or the ectoderm. To resolve this question, it is necessary to expand the number of models for investigation of the early axial patterning. Here, we show that three Hox genes of the polychaete Alitta virens (formerly Nereis virens, Annelida, Lophotrochozoa)- Hox2, Hox4, and Lox5-are expressed in the mesodermal anlagen of the three future larval chaetigerous segments in spatially colinear manner before the initiation of Hox expression in the larval ectoderm. This is the first evidence of sequential Hox gene expression in the mesoderm of protostomes to date. [ABSTRACT FROM AUTHOR]

The Hox gene cluster has been a major focus in evolutionary developmental biology. This is because of its key role in patterning animal development and widespread examples of changes in Hox genes being linked to the evolution of animal body plans and morphologies. Also, the distinctive organisation of the Hox genes into genomic clusters in which the order of the genes along the chromosome corresponds to the order of their activity along the embryo, or during a developmental process, has been a further source of great interest. This is known as Colinearity, and it provides a clear link between genome organisation and the regulation of genes during development, with distinctive changes marking evolutionary transitions. The Hox genes are not alone, however. The homeobox genes are a large super-class, of which the Hox genes are only a small subset, and an ever-increasing number of further gene clusters besides the Hox are being discovered. This is of great interest because of the potential for such gene clusters to help understand major evolutionary transitions, both in terms of changes to development and morphology as well as evolution of genome organisation. However, there is uncertainty in our understanding of homeobox gene cluster evolution at present. This relates to our still rudimentary understanding of the dynamics of genome rearrangements and evolution over the evolutionary timescales being considered when we compare lineages from across the animal kingdom. A major goal is to deduce whether particular instances of clustering are primary (conserved from ancient ancestral clusters) or secondary (reassortment of genes into clusters in lineage-specific fashion). The following summary of the various instances of homeobox gene clusters in animals, and the hypotheses about their evolution, provides a framework for the future resolution of this uncertainty.

Regression is an important method for characterizing the form of natural selection from individual-based data. Many kinds of regression analysis exist, but few are regularly employed in studies of natural selection. I provide an overview of some of the main underused types of regression analysis by applying them to test analyses of viability selection for lamb traits in Soay sheep ( Ovis aries). This exercise highlights known problems with existing methods, uncovers some new ones and also reveals ways to harness underused methods to get around these problems., I first estimate selection gradients using generalized linear models, combined with recently published methods for obtaining quantitatively interpretable selection gradient estimates from arbitrary regression models of trait-fitness relationships. I then also apply generalized ridge regression, the lasso and projection-pursuit regression, in each case also deriving selection gradients. I compare inferences of nonlinear selection by diagonalization of the γ matrix and by projection-pursuit regression., Selection gradient estimates generally correspond across different regression methods. Although there is little evidence for nonlinear selection in the test data sets, very problematic aspects of the behaviour of analysis based on diagonalization of the γ are apparent. In addition to better-known problems, (i) the direction and magnitude of estimated major axes of quadratic selection are biased towards directions of phenotype that have little variance, and (ii) the magnitudes of selection of major axes of variance-standardized γ are not themselves interpretable in any standardized way., While all regression-based methods for analysis of selection have useful properties, projection-pursuit regression seems to stand out. This method can (i) provide both dimensionality reduction, (ii) be the basis for inference of quantitatively interpretable selection gradients and (iii) by characterizing major axes of selection, rather than of linear or quadratic selection separately, provide biologically interpretable inference of nonlinear selection. [ABSTRACT FROM AUTHOR]

Background: ParaHox and Hox genes are thought to have evolved from a common ancestral ProtoHox cluster or from tandem duplication prior to the divergence of cnidarians and bilaterians. Similar to Hox clusters, chordate ParaHox genes including Gsx, Xlox, and Cdx, are clustered and their expression exhibits temporal and spatial colinearity. In non-chordate animals, however, studies on the genomic organization of ParaHox genes are limited to only a few animal taxa. Hemichordates, such as the Enteropneust acorn worms, have been used to gain insights into the origins of chordate characters. In this study, we investigated the genomic organization and expression of ParaHox genes in the indirect developing hemichordate acorn worm Ptychodera flava. Results: We found that P. flava contains an intact ParaHox cluster with a similar arrangement to that of chordates. The temporal expression order of the P. flava ParaHox genes is the same as that of the chordate ParaHox genes. During embryogenesis, the spatial expression pattern of PfCdx in the posterior endoderm represents a conserved feature similar to the expression of its orthologs in other animals. On the other hand, PfXlox and PfGsx show a novel expression pattern in the blastopore. Nevertheless, during metamorphosis, PfXlox and PfCdx are expressed in the endoderm in a spatially staggered pattern similar to the situation in chordates. Conclusions: Our study shows that P. flava ParaHox genes, despite forming an intact cluster, exhibit temporal colinearity but lose spatial colinearity during embryogenesis. During metamorphosis, partial spatial colinearity is retained in the transforming larva. These results strongly suggest that intact ParaHox gene clustering was retained in the deuterostome ancestor and is correlated with temporal colinearity. [ABSTRACT FROM AUTHOR]

Background: The ParaHox genes are thought to be major players in patterning the gut of several bilaterian taxa. Though this is a fundamental role that these transcription factors play, their activities are not limited to the endoderm and extend to both ectodermal and mesodermal tissues. Three genes compose the ParaHox group: Gsx, Xlox and Cdx. In some taxa (mostly chordates but to some degree also in protostomes) the three genes are arranged into a genomic cluster, in a similar fashion to what has been shown for the better-known Hox genes. Sea urchins possess the full complement of ParaHox genes but they are all dispersed throughout the genome, an arrangement that, perhaps, represented the primitive condition for all echinoderms. In order to understand the evolutionary history of this group of genes we cloned and characterized all ParaHox genes, studied their expression patterns and identified their genomic loci in a member of an earlier branching group of echinoderms, the asteroid Patiria miniata. Results: We identified the three ParaHox orthologs in the genome of P. miniata. While one of them, PmGsx is provided as maternal message, with no zygotic activation afterwards, the other two, PmLox and PmCdx are expressed during embryogenesis, within restricted domains of both endoderm and ectoderm. Screening of a Patiria bacterial artificial chromosome (BAC) library led to the identification of a clone containing the three genes. The transcriptional directions of PmGsx and PmLox are opposed to that of the PmCdx gene within the cluster. Conclusions: The identification of P. miniata ParaHox genes has revealed the fact that these genes are clustered in the genome, in contrast to what has been reported for echinoids. Since the presence of an intact cluster, or at least a partial cluster, has been reported in chordates and polychaetes respectively, it becomes clear that within echinoderms, sea urchins have modified the original bilaterian arrangement. Moreover, the sea star ParaHox domains of expression show chordate-like features not found in the sea urchin, confirming that the dynamics of gene expression for the respective genes and their putative regulatory interactions have clearly changed over evolutionary time within the echinoid lineage. [ABSTRACT FROM AUTHOR]

Whole-genome duplications (WGDs) have recurred in the evolution of angiosperms, resulting in many duplicated chromosomal segments. Local gene duplications are also widespread in angiosperms. WGD-derived duplicates, that is, ohnologs, and local duplicates often show contrasting patterns of gene retention and evolution. However, many genes in angiosperms underwent multiple gene duplication events, possibly by different modes, indicating that different modes of gene duplication are not mutually exclusive. In two representative angiosperm genomes, Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), we found that 9.6% and 11.3% of unique ohnologs, corresponding to 15.5% and 17.1% of ohnolog pairs, were also involved in local duplications, respectively. Locally duplicated ohnologs are widely distributed in different duplicated chromosomal segments and functionally biased. Coding sequence divergence between duplicated genes is denoted by nonsynonymous (Ka) and synonymous (Ks) substitution rates. Locally duplicated ohnolog pairs tend to have higher Ka, Ka/Ks, and gene expression divergence than nonlocally duplicated ohnolog pairs. Locally duplicated ohnologs also tend to have higher interspecies sequence divergence. These observations indicate that locally duplicated ohnologs evolve faster than nonlocally duplicated ohnologs. This study highlights the necessity to take local duplications into account when analyzing the evolutionary dynamics of ohnologs. [ABSTRACT FROM AUTHOR]

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The Hox genes pattern the anterior-posterior axis in developing embryos through tightly regulated, partially overlapping, temporal and spatial expression domains. Initial regulation of Hox expression is important to establish these overlapping transcription domains. The Cdx homeodomain factors have been proposed as Hox regulators, but their precise role and mechanism during this regulatory interaction remain unclear. In Xenopus embryos, HoxC8 transcripts begin to accumulate during mid/late gastrula. Cdx1 overexpression and knockdown lead to precocious or slower HoxC8 expression, respectively. The mouse HoxC8 early enhancer when introduced into Xenopus embryos recapitulates the endogenous XHoxC8 temporal expression pattern and shows the same responsiveness to Cdx1 regulation. Three pairs of conserved Cdx binding sites were identified within the HoxC8 early enhancer. We demonstrate that Cdx1 binds directly these responsive elements during embryogenesis, as part of the mechanism for the timely activation of HoxC8 expression. We define the function and mechanism of Cdx1 regulation on HoxC8 expression and suggest the possibility that the temporal changes in Cdx activity levels during gastrulation, combined with differential DNA binding affinity, might play a role in the establishment of Hox sequential activation. [ABSTRACT FROM AUTHOR]

Time-series of half-hourly PM10 concentrations and meteorological data measured near industrial sites where dusty materials are processed can be used to estimate PM10 source strengths for these activities using reverse modelling. Reverse modelling starts with building an over-determined system of linear equations: ObservedCmj=ComputedCmj(known sources) + Σi=1,nComputedCmj(Qi) where the N values of Q1 are determined by least squares regression. The paper focuses on regression solutions tainted by noise fitting that are physically meaningless, on rules to reduce the risk for noise fitting, and on how to use cumulative frequency distributions, time series for different averaging times and pollutant roses to obtain a physically sound solution. [ABSTRACT FROM AUTHOR]

Although commonplace in human disease genetics, genome.wide association (GWA) studies have only relatively recently been applied to plants. Using 32 phenotypes in the inbreeding crop barley, we report GWA mapping of 15 morphological traits across -∼500 cultivars genotyped with 1,536 SNPs. In contrast to the majority of human GWA studies, we observe high levels of linkage disequilibrium within and between chromosomes. Despite this, GWA analysis readily detected common alleles of high penetrance. To investigate the potential of combining GWA mapping with comparative analysis to resolve traits to candidate polymorphism level in unsequenced genomes, we fine-mapped a selected phenotype (anthocyanin pigmentation) within a 140-kb interval containing three genes. Of these, resequencing the putative anthocyanin path. way gene HvbHLH1 identified a deletion resulting in a premature stop codon upstream of the basic helix.loop-helix domain, which was diagnostic for lack of anthocyanin in our association and biparental mapping populations. The methodology described here is transferable to species with limited genomic resources, providing a paradigm for reducing the threshold of map-based cloning in unsequenced crops. [ABSTRACT FROM AUTHOR]

Segmentation is an important process that is frequently used during development to segregate groups of cells with distinct features. Segmental compartments provide a mechanism for generating and organizing regional properties along an embryonic axis and within tissues. In vertebrates the development of two major systems, the hindbrain and the paraxial mesoderm, displays overt signs of compartmentalization and depends on the process of segmentation for their functional organization. The hindbrain plays a key role in regulating head development, and it is a complex coordination center for motor activity, breathing rhythms, and many unconscious functions. The paraxial mesoderm generates somites, which give rise to the axial skeleton. The cellular processes of segmentation in these two systems depend on ordered patterns of Hox gene expression as a mechanism for generating a combinatorial code that specifies unique identities of the segments and their derivatives. In this review, we compare and contrast the signaling inputs and transcriptional mechanisms by which Hox gene regulatory networks are established during segmentation in these two different systems. [ABSTRACT FROM AUTHOR]

Hox genes are known to specify spatial identities along the anterior-posterior axis during embryogenesis. In vertebrates and most other deuterostomes, they are arranged in sets of uninterrupted clusters on chromosomes, and are in most cases expressed in a "colinear" fashion, in which genes closer to the 3′-end of the Hox clusters are expressed earlier and more anteriorly and genes close to the 5′-end of the clusters later and more posteriorly. In this review, we summarize the current understanding of how Hox gene clusters have been modified from basal lineages of deuterostomes to diverse taxa of vertebrates. Our parsimony reconstruction of Hox cluster architecture at various stages of vertebrate evolution highlights that the variation in Hox cluster structures among jawed vertebrates is mostly due to secondary lineage-specific gene losses and an additional genome duplication that occurred in the actinopterygian stem lineage, the teleost-specific genome duplication (TSGD). [ABSTRACT FROM AUTHOR]

Loquat [ Eriobotrya japonica (Thunb.) Lindl.] is a Rosaceae fruit species of growing interest as an alternative to the main fruit crops. However, only a few genetic studies have been carried out on this species. This paper reports the construction of the first genetic maps of two loquat cultivars based on AFLP and microsatellite markers from Malus, Eriobotrya, Pyrus and Prunus genera. An F1 population consisting of 81 individuals, derived from the cross between ‘Algerie’ and ‘Zaozhong-6’ cultivars, was used to construct both maps. A total of 111 scorable simple sequence repeat (SSR) loci resulted from the testing of 440 SSR primer pairs in the analyzed progeny and the SSR transferability to Eriobotrya was found to be 74% from apple, 58% from pear and 49% from Prunus spp. In addition, 183 AFLP polymorphic bands were produced using 42 primer combinations. The ‘Algerie’ map was organized in 17 linkage groups covering a distance of 900 cM and comprising 177 loci (83 SSRs and 94 AFLPs) with an average marker distance of 5.1 cM. Self-incompatibility trait was mapped at the distal part of the LG17 linkage group, as previously reported in Malus and Pyrus. The ‘Zaozhong-6’ map covered 870 cM comprising 146 loci (64 SSRs and 82 AFLPs) with an average marker distance of 5.9 cM. The 44 SSRs and the 48 AFLPs share in common by both maps were essentially collinear and, moreover, the order of the 75% of apple and pear SSRs mapped in Eriobotrya was shown to be consistent across the Maloideae subfamily. As a whole, these maps represent a useful tool to facilitate loquat breeding and an interesting framework for map comparison in the Rosaceae. [ABSTRACT FROM AUTHOR]

Brachypodium, a wild temperate grass with a small genome, was recently proposed as a new model organism for the large-genome grasses. In this study, we evaluated gene content and microcolinearity between diploid wheat ( Triticum monococcum), Brachypodium sylvaticum, and rice at a local genomic region harboring the major wheat domestication gene Q. Gene density was much lower in T. monococcum (one per 41 kb) because of gene duplication and an abundance of transposable elements within intergenic regions as compared to B. sylvaticum (one per 14 kb) and rice (one per 10 kb). For the Q gene region, microcolinearity was more conserved between wheat and rice than between wheat and Brachypodium because B. sylvaticum contained two genes apparently not present within the orthologous regions of T. monococcum and rice. However, phylogenetic analysis of Q and leukotriene A-4 hydrolase-like gene orthologs, which were colinear among the three species, showed that Brachypodium is more closely related to wheat than rice, which agrees with previous studies. We conclude that Brachypodium will be a useful tool for gene discovery, comparative genomics, and the study of evolutionary relationships among the grasses but will not preclude the need to conduct large-scale genomics experiments in the Triticeae. [ABSTRACT FROM AUTHOR]

Invertase (EC 3.2.1.26) plays a key role in carbon utilization as it catalyzes the irreversible hydrolysis of sucrose into glucose and fructose. The invertase family in plants is composed of two sub-families thought to have distinct evolutionary origins and can be distinguished by their pH optima for activity: acid invertases and neutral/alkaline invertases. The acid invertases apparently originated in eubacteria and are targeted to the cell wall and vacuole, while neutral/alkaline invertases apparently originated in cyanobacteria and function in the cytosol. The recently sequenced genome of Populus trichocharpa (Torr. and Gray) allowed us to identify the genes encoding invertase in this woody perennial. Here we describe the identification of eight acid invertase genes; three of which belong to the vacuolar targeted group ( PtVIN1–3), and five of which belong to the cell wall targeted group ( PtCIN1–5). Similarly, we report the identification of 16 neutral/alkaline invertase genes ( PtNIN1–16). Expression analyses using whole genome microarrays and RT-PCR reveal evidence for expression of all invertase family members. An examination of the micro-syntenic regions surrounding the poplar invertase genes reveals extensive colinearity with Arabidopsis invertases. We also find evidence for expression of a novel intronless vacuolar invertase ( PtVIN1), which apparently arose from a processed PtVIN2 transcript that re-inserted into the genome. To our knowledge, this is the first intronless invertase found in plants. This work increases the understanding of the role this family plays in carbon allocation and partitioning in forest trees as well as its evolutionary development. [ABSTRACT FROM AUTHOR]

Hox genes form clusters. Invertebrates and Amphioxus have only one hox cluster, but in vertebrates, they are multiple, i.e., four in the basal teleost fish Polyodon and tetrapods ( HoxA, B, C, D), but seven or eight in common teleosts. We earlier completely sequenced the entire hox gene loci in medaka fish, showing a total of 46 hox genes to be encoded in seven clusters ( hoxAa, Ab, Ba, Bb, Ca, Da, Db). Among them, hoxAa, hoxAb and hoxDa clusters are presumed to be important for fin-to-limb evolution because of their key role in forelimb and pectoral fin development. In the present study, we compared genome organization and nucleotide sequences of the hoxAa and hox Ab clusters to these of tetrapod HoxA clusters, and found greater similarity in hoxAa case. We then analyzed expression of Abd-B family genes in the clusters. In the trunk, those from the hoxAa cluster, i.e., hoxA9a, hoxA10a, hoxA11a and hoxA13a, were expressed in a manner keeping the colinearity rule of the hox expression as those of tetrapods, while those from the hoxAb cluster, i.e., hoxA9b, hoxA10b, hoxA11b and hoxA13b, were not. In the pectoral fins, the hoxAa cluster was expressed in split domains and did not obey the rule. By contrast, those from the hoxAb and hoxDa clusters were expressed in a manner keeping the rule, i.e., an ancestral pattern similar to those of tetrapods. It is plausible that this differential expression of the two clusters is caused by changes occurred in global control regions after cluster duplications. [ABSTRACT FROM AUTHOR]

The high-quality rice genome sequence is serving as a reference for comparative genome analysis in crop plants, especially cereals. However, early comparisons with bread wheat showed complex patterns of conserved synteny (gene content) and colinearity (gene order). Here, we show the presence of ancient duplicated segments in the progenitor of wheat, which were first identified in the rice genome. We also show that single-copy (SC) rice genes, those representing unique matches with wheat expressed sequence tag (EST) unigene contigs in the whole rice genome, show more than twice the proportion of genes mapping to syntenic wheat chromosome as compared to the multicopy (MC) or duplicated rice genes. While 58.7% of the 1,244 mapped SC rice genes were located in single syntenic wheat chromosome groups, the remaining 41.3% were distributed randomly to the other six non-syntenic wheat groups. This could only be explained by a background dispersal of genes in the genome through transposition or other unknown mechanism. The breakdown of rice–wheat synteny due to such transpositions was much greater near the wheat centromeres. Furthermore, the SC rice genes revealed a conserved primordial gene order that gives clues to the origin of rice and wheat chromosomes from a common ancestor through polyploidy, aneuploidy, centromeric fusions, and translocations. Apart from the bin-mapped wheat EST contigs, we also compared 56,298 predicted rice genes with 39,813 wheat EST contigs assembled from 409,765 EST sequences and identified 7,241 SC rice gene homologs of wheat. Based on the conserved colinearity of 1,063 mapped SC rice genes across the bins of individual wheat chromosomes, we predicted the wheat bin location of 6,178 unmapped SC rice gene homologs and validated the location of 213 of these in the telomeric bins of 21 wheat chromosomes with 35.4% initial success. This opens up the possibility of directed mapping of a large number of conserved SC rice gene homologs in wheat. Overall, only 46.4% of these SC genes code for proteins with known functional domains; the remaining 53.6% have unknown function, and hence, represent an important, but yet, under explored category of genes. [ABSTRACT FROM AUTHOR]

Abstract: The ANTP family of homeodomain transcription factors consists of three major groups, the NKL, the extended Hox, and the Hox/ParaHox family. Hox genes and ParaHox genes are often linked in the genome forming two clusters of genes, the Hox cluster and the ParaHox cluster, and are expressed along the major body axis in a nested fashion, following the relative positions of the genes within these clusters, a property called colinearity. While the presences of a Hox cluster and a ParaHox cluster appear to be primitive for bilaterians, few taxa have actually been examined for spatial and temporal colinearity, and, aside from chordates, even fewer still manifest it. Here we show that the ParaHox genes of the sea urchin Strongylocentrotus purpuratus show both spatial and temporal colinearity, but with peculiarities. Specifically, two of the three ParaHox genes-discovered through the S. purpuratus genome project-Sp-lox and Sp-Cdx, are expressed in the developing gut with nested domains in a spatially colinear manner. However, transcripts of Sp-Gsx, although anterior of Sp-lox, are detected in the ectoderm and not in the gut. Strikingly, the expression of the three ParaHox genes would follow temporal colinearity if they were clustered in the same order as in chordates, but each ParaHox gene is actually found on a different genomic scaffold (>300 kb each), which suggests that they are not linked into a single coherent cluster. Therefore, ParaHox genes are dispersed in the genome and are used during embryogenesis in a temporally and spatially coherent manner, whereas the Hox genes, now fully sequenced and annotated, are still linked and are employed as a complex only during the emergence of the adult body plan in the larva. [Copyright &y& Elsevier]

Fortunately, I began research in 1950 when the basic concepts of microbial genetics could be explored experimentally. I began with bacteriophage λ and tried to establish the colinearity of its linkage map with its DNA molecule. My students and I worked out the regulation of λ repressor synthesis for the establishment and maintenance of lysogeny. We also investigated the proteins responsible for assembly of the phage head. Using cell extracts, we discovered how to package DNA inside the head in vitro. Around 1972, I began to use molecular genetics to understand the developmental biology of Myxococcus xanthus. In particular, I wanted to learn how myxococcus builds its multicellular fruiting body within which it differentiates spores. We identified two cell-to-cell signals used to coordinate development. We have elucidated, in part, the signal transduction pathway for C-signal that directs the morphogenesis of a fruiting body. [ABSTRACT FROM AUTHOR]

Many studies have demonstrated that student motivation is an important factor in student learning. The recently proposed General Model of Instructional Communication, however, does not include motivation. Based on the assumption that student motivation may be an important factor in student learning, particularly long-term learning and retention, the present research examined relationships of student motivation with the four primary teacher communication behaviors included in that model. Student motivation was also found to be highly associated with instructional outcomes (affect for course content and affect toward teacher) included in the General Model. Results indicate that student motivation should be added to that model. Potential problems associated with colinearity and halo effects are discussed. [ABSTRACT FROM AUTHOR]

The Tsn1 gene in wheat confers sensitivity to a proteinaceous host-selective toxin (Ptr ToxA) produced by the tan spot fungus ( Pyrenophora tritici-repentis) and lies within a gene-rich region of chromosome 5B. To use the rice genome sequence information for the map-based cloning of Tsn1, colinearity between the wheat genomic region containing Tsn1 and the rice genome was determined at the macro- and microlevels. Macrocolinearity was determined by testing 28 expressed sequence markers (ESMs) spanning a 25.5-cM segment and encompassing Tsn1 for similarity to rice sequences. Twelve ESMs had no similarity to rice sequences, and 16 had similarity to sequences on seven different rice chromosomes. Segments of colinearity with rice chromosomes 3 and 9 were identified, but frequent rearrangements and disruptions occurred. Microcolinearity was determined by testing the sequences of 26 putative genes identified from BAC contigs of 205 and 548 kb in length and flanking Tsn1 for similarity to rice genomic sequences. Fourteen of the predicted genes detected orthologous sequences on six different rice chromosomes, whereas the remaining 12 had no similarity with rice sequences. Four genes were colinear on rice chromosome 9, but multiple disruptions, rearrangements, and duplications were observed in wheat relative to rice. The data reported provide a detailed analysis of a region of wheat chromosome 5B that is highly rearranged relative to rice. [ABSTRACT FROM AUTHOR]

Four individual linkage maps were constructed from two crosses for the species complex Picea mariana (Mill.) B.S.P. × Picea rubens Sarg in order to integrate their information into a composite map and to compare with other Pinaceae. For all individual linkage maps, 12 major linkage groups were recovered with 306 markers per map on average. Before building the composite linkage map, the common male parent between the two crosses made it possible to construct a reference linkage map to validate the relative position of homologous markers. The final composite map had a length of 2,319 cM (Haldane) and contained a total of 1,124 positioned markers, including 1,014 AFLPs, 3 RAPDs, 53 SSRs, and 54 ESTPs, assembled into 12 major linkage groups. Marker density of the composite map was statistically homogenous and was much higher (one marker every 2.1 cM) than that of the individual linkage maps (one marker every 5.7 to 7.1 cM). Synteny was well conserved between individual, reference, and composite linkage maps and 94% of homologous markers were colinear between the reference and composite maps. The combined information from the two crosses increased by about 24% the number of anchor markers compared to the information from any single cross. With a total number of 107 anchor markers (SSRs and ESTPs), the composite linkage map is a useful starting point for large-scale genome comparisons at the intergeneric level in the Pinaceae. Comparisons of this map with those in Pinus and Pseudotsuga allowed the identification of one breakdown in synteny where one linkage group homoeologous to both Picea and Pinus corresponded to two linkage groups in Pseudotsuga. Implications for the evolution of the Pinaceae genome are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Patients with unilateral neglect and extinction show a profound lack of awareness of stimuli presented contralateral to their lesion. However, many processes of perception are intact and contralesional stimuli seem to reach a high level of representation, perceptual and semantic. Some of these processes can work to decrease the magnitude of the attentional deficit. Here, we examine two of these intact processes, feature detection and perceptual grouping. First, we demonstrate that feature detection occurs in parallel in the contralesional visual fields of neglect and extinction patients. Second, we attempt to dissociate the influence of perceptual contours across the vertical meridian from the presence of an object or higher-level perceptual unit (or group) that may be created by these contours. We find that connections across the midline affect attentional deficits independently of the objects they may create. This suggests that several effects of grouping on neglect and extinction may be mediated by long-range cortical interactions that arise from connections across the vertical meridian. [Copyright &y& Elsevier]

Comparative RFLP mapping has revealed extensive conservation of marker order in different grass genomes. However, microcolinearity studies at the sequence level have shown rapid genome evolution and many exceptions to colinearity. Most of these studies have focused on a limited size of genomic fragment and the extent of microcolinearity over large distances or across entire genomes remains poorly characterized in grasses. Here, we have investigated the microcolinearity between the rice genome and a total of 1,500 kb from physical BAC contigs on wheat chromosome 1AS. Using ESTs mapped in wheat chromosome bins as an additional source of physical data, we have identified 27 conserved orthologous sequences between wheat chromosome 1AS and a region of 1,210 kb located on rice chromosome 5S. Our results extend the orthology described earlier between wheat chromosome group 1S and rice chromosome 5S. Microcolinearity was found to be frequently disrupted by rearrangements which must have occurred after the divergence of wheat and rice. At the Lr10 orthologous loci, microrearrangements were due to the insertion of mobile elements, but also originated from gene movement, amplification, deletion and inversion. These mechanisms of genome evolution are at the origin of the mosaic conservation observed between the orthologous regions. Finally, in silico mapping of wheat genes identified an intragenomic colinearity between fragments from rice chromosome 1L and 5S, suggesting an ancestral segmental duplication in rice. [ABSTRACT FROM AUTHOR]

HOX genes are well known as master control genes in embryonic morphogenesis. We hypothesized that HOX genes give cells spatial information to maintain tissue- or organ-specificity in adult body and that the deregulated expression of HOX genes results in tumor development. We established a comprehensive analysis system to quantify expression of 39 human HOX genes based on the real-time reverse transcription PCR (RT-PCR) method. Analysis of 39 HOX genes of 20 normal adult organs by this system revealed that 5′ HOX genes were expressed in organs in the caudal parts of the body, and that the more caudal regions the more numbers of HOX genes were expressed. It was also found that the expression patterns of HOX genes were more similar in the adjacent genes on the same cluster rather than in those belonging to the same paralogs. Compared with normal thyroid tissues, thyroid cancer cell lines showed the altered expression of some HOX genes, especially Abd-B homeobox family genes. Our results showed that HOX genes were organ-specifically expressed in adult body and that the deregulated expressions of Abd-B family genes were implicated in thyroid tumor development. [Copyright &y& Elsevier]

A new stepwise regression program (SROV) for the construction of optimal (stable and of highest possible accuracy) regression models comprised of linear combination of independent variables and their non-linear functions is described. The program uses for regression QR decomposition based on Gram–Schmidth orthogonalization, which is highly resilient to numerical error propagation. Variables are selected to enter the regression model according to their level of correlation with the dependent variable and they are removed from further consideration when their residual information gets below the noise level. The use of this program is demonstrated in two examples. In both examples the program identifies an optimal and stable regression model and several sub-optimal models. The existence of sub-optimal models provides additional insight regarding the relationships that exist between the explanatory variables, between the explanatory variables and the dependent variable and information on model related uncertainties caused by sample size and experimental error. [Copyright &y& Elsevier]

A genetic linkage map of mungbean (Vigna radiata, 2n = 2x = 22) consisting of 255 RFLP loci was developed using a recombinant inbred population of 80 individuals. The population was derived from an inter-subspecific cross between the cultivated mungbean variety 'Berken' and a wild mungbean genotype 'ACC 41' (V. radiata subsp. sublobata). The total length of the map, which comprised 13 linkage groups, spanned 737.9 cM with an average distance between markers of 3.0 cM and a maximum distance between linked markers of 15.4 cM. The mungbean map was compared to a previously published map of lablab (Lablab purpureus, 2n = 2x = 24) using a common set of 65 RFLP probes. In contrast to some other comparative mapping studies among members of the Fabaceae, where a high level of chromosomal rearrangement has been observed, marker order between mungbean and lablab was found to be highly conserved. However, the two genomes have apparently accumulated a large number of duplications/deletions after they diverged. [ABSTRACT FROM AUTHOR]

We have constructed bacterial artificial chromosome (BAC) libraries from two grass species that reproduce by apospory, a form of gametophytic apomixis. The library of an apomictic polyhaploid genotype (line MS228-20, with a 2C genome size of approximately 4,500 Mbp) derived from a cross between the obligate apomict, Pennisetum squamulatum, and pearl millet (P. glaucum) comprises 118,272 clones with an average insert size of 82 kb. The library of buffelgrass (Cenchrus ciliaris, apomictic line B-12-9, with a 2C genome size of approximately 3,000 Mbp) contains 68,736 clones with an average insert size of 109 kb. Based on the genome sizes of these two lines and correcting for the number for false-positive and organellar clones, library coverages were found to be 3.7 and 4.8 haploid genome equivalents for MS 228-20 and B12-9, respectively. Both libraries were screened by hybridization with six SCARs (sequence-characterized amplified regions), whose tight linkage in a single apospory-specific genomic region had been previously demonstrated in both species. Analysis of these BAC clones indicated that some of the SCAR markers are actually amplifying duplicated regions linked in coupling in both genomes and that restriction enzyme mapping will be necessary to sort out the duplications. [ABSTRACT FROM AUTHOR]

The genomes of grasses are very different in terms of size, ploidy level and chromosome number. Despite these significant differences, it was found by comparative mapping that the linear order (colinearity) of genetic markers and genes is very well conserved between different grass genomes. The potential of such conservation has been exploited in several directions, e.g. in defining rice as a model genome for grasses and in designing better strategies for positional cloning in large genomes. Recently, the development of large insert libraries in species such as maize, rice, barley and diploid wheat has allowed the study of large stretches of DNA sequence and has provided insight into gene organization in grasses. It was found that genes are not distributed randomly along the chromosomes and that there are clusters of high gene density in species with large genomes. Comparative analysis performed at the DNA sequence level has demonstrated that colinearity between the grass genomes is retained at the molecular level (microcolinearity) in most cases. However, detailed analysis has also revealed a number of exceptions to microcolinearity, which have given insight into mechanisms that are involved in grass‐genome evolution. In some cases, the use of rice as a model to support gene isolation from other grass genomes will be complicated by local rearrangements. In this Botanical Briefing, we present recent progress and future prospects of comparative genomics in grasses. [ABSTRACT FROM PUBLISHER]

Aegilops longissima Schw. et Musch. (2n= 2x=14, SlSl) and Aegilops sharonensis Eig. (2n=2x=14, SlSl) are diploid species belonging to the section Sitopsis in the tribe Triticeae and potential donors of useful genes for wheat breeding. A comparative genetic map was constructed of the Ae. longissima genome, using RFLP probes with known location in wheat. A high degree of conserved colinearity was observed between the wild diploid and basic wheat genome, represented by the D genome of cultivated wheat. Chromosomes 1Sl, 2Sl, 3Sl, 5Sl and 6Sl are colinear with wheat chromosomes 1D, 2D, 3D, 5D and 6D, respectively. The analysis confirmed that chromosomes 4Sl and 7Sl are translocated relative to wheat. The short arms and major part of the long arms are homoeologous to most of wheat chromosomes 4D and 7D respectively, but the region corresponding to the distal segment of 7D was translocated from 7SlL to the distal region of 4SlL. The map and RFLP markers were then used to analyse the genomes and added chromosomes in a set of ’Chinese Spring’ (CS)/Ae. longissima chromosome additions. The study confirmed the availability of disomic CS/Ae. longissima addition lines for chromosomes 1Sl, 2Sl, 3Sl, 4Sl and 5Sl. An as yet unpublished set of Ae. sharonensis chromosome addition lines were also available for analysis. Due to the gametocidal nature of Ae. sharonensis chromosomes 2Sl and 4Sl, additions 1Sl, 3Sl, 5Sl, 6Sl and 7Sl were produced in a (4D)4Sl background, and 2Sl and 4Sl in a euploid wheat background. The analysis also confirmed that the 4/7 translocation found in Ae. longissima was not present in Ae. sharonensis although the two wild relatives of wheat are considered to be closely related. The phenotypes of the Ae. sharonensis addition lines are described in an Appendix. [ABSTRACT FROM AUTHOR]

A new topological charge-transfer index is applied toelucidate the polar character of hydrocarbons. The dipole moments calculated by algebraic and vector semisums of charge-transfer indices are defined in this work. The combination of the charge-transfer indices allows the estimation of the molecular dipole moments. The ability of the indices for the description of the molecular charge distribution is established by comparing them with the dipole moment of a heterogeneous set of 57 polar and 53 apolar hydrocarbons. Linear and nonlinear correlation models are obtained. The new charge-transfer index, μvec, elucidates whether hydrocarbons are apolar, and improves the multivariable nonlinear regression equation for the dipole moment. When comparing with previous results, smaller superpositions of the corresponding pairs Gk, Jk are observed in our fits. This diminishes the risk of colinearity. [ABSTRACT FROM AUTHOR]

High-resolution genetic and physical maps were constructed for the region of chromosome 2 containing the major fruit-shape locus ovate. A total of 3000 NIL F[sub 2] and F[sub 3] NILs derived from Lycopersicon esculentum cv. Yellow Pear (TA503) × L. pennellii (a wild tomato) were used to position ovate adjacent to the marker TG645 and flanked by markers TX700 and BA10R (a 0.03-cM interval). BAC libraries and a BIBAC library were screened with the closest marker, TG645. Genetic mapping with the ends of isolated BAC clones revealed that two BAC clones (100 and 140 kb) both contained the ovate locus. Screening of sequences from these BAC clones revealed synteny between this segment of tomato chromosome 2 and the chromosome-4 region of Arabidopsis containing the BAC clone ATAP22. Microsynteny between the two genomes was exploited to find additional markers near the ovate locus. The placement of ovate on a BAC clone will now allow cloning of this locus and, hence, may open the door to understanding the molecular basis of fruit development and also facilitate the genetic engineering of fruit-shape characteristics. This also represents the first time that microsynteny with Arabidopsis has been exploited for positional cloning purposes in a different plant family.Key words: map, fruit development, colinearity, positional cloning.Des cartes génétique et physique à haute résolution ont été construites pour la région du chromosome 2 qui porte le locus ovate, un déterminant majeur de la forme des fruits. Un ensemble de 3000 lignées quasi-isogéniques F[sub 2] et F[sub 3] dérivées du croisement entre le Lycopersicon esculentum cv. Yellow Pear (TA503) et le L. pennellii (une tomate sauvage) ont été utilisées afin de situer le locus ovate à proximité du marqueur TG645 et bordé des marqueurs TX700 et BA10R (à 0,03 cM). Des banques de clones BAC et une banque de clones BIBAC ont été criblées avec le marqueur le plus proche, TG645. Des travaux de cartographie génétique réalisés avec les extrémités des BAC isolés ont révélé que deux clones BAC (100 et 140 kb) contenaient tous deux le locus ovate. L'examen de séquences de ces clones BAC a révélé de la synténie entre ce segment du chromosome 2 de la tomate et la région du chromosome 4 d'Arabidopsis qui est contenue dans le clone BAC ATAP22. La microsynténie entre ces deux génomes a été exploitée afin de trouver des marqueurs additionnels à proximité du locus ovate. La localisation du locus sur un clone BAC permettra dorénavant le clonage de ce locus et pourrait ainsi ouvrir la voie à une meilleure compréhension des mécanismes moléculaires régissant le développement du fruit en plus de rendre possible la modification de la forme des fruits par ingénierie génétique. Ceci constitue également le premier travaille rapportant l'exploitation de microsynténie avec Arabidopsis pour des fins de clonage positionnel au sein d'une famille différente au sein du règne végétal.Mots clés : carte, développement du fruit, colinéarité, clonage positionnel.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Comparative genetic maps were constructed of the pearl millet genome with foxtail millet and used to describe the homoeology between the genomes of pearl millet, foxtail millet and rice. Despite the close taxonomic relationship of pearl and foxtail millet, their genomes were highly, rearranged. A comparison of the millet and rice genomes indicated that most of these rearrangements were likely to have taken place in pearl millet. Two duplications were identified in pearl millet. A duplication between the distal segments of linkage groups 1 and 4 corresponds to the ancient duplication previously identified between rice chromosome arms 11S and 12S and foxtail millet chromosomes VII and VIII. The other putative duplication, also between regions of linkage groups 1 and 4, is likely to be species-specific. The exploitation of the comparative maps in pearl millet research is discussed. [ABSTRACT FROM AUTHOR]