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1. The onset of lay, quality of eggs during early lay and gonadal development of both sexes were analysed in meat-type lines of Japanese quail, HG and LG divergently selected for high and low relative weight gain between 11 and 28 d of age, respectively, and constant body weight (BW) at 49 d of age. 2. The LG line was sexually mature at an earlier age and lower BW than the HG line. This corresponded with the trend during embryonic and early postnatal development. 3. Analysis of gonads also confirmed earlier sexual development in the LG than in the HG line. In both lines, the growth of testes was detected about one week earlier than the growth of ovary. 4. Despite the different age and BW at onset of lay, HG and LG quail commenced lay at the same degree of maturity (about 90% of adult BW). This implied that the onset of sexual maturity could be identified as a point on the growth curve which terminates the linear phase. 5. When compared with the LG line, the HG line was characterised by a longer acceleration and shorter retardation phase of the growth curve. This difference is seen as an important determinant of line differences in growth and reproductive performance.

Pectoralis major muscle morphology was studied in both sexes of a turkey line (E) selected long-term for increased egg production and its randombred control (RBC1) from 25 d of incubation through 20 wk posthatch. Pectoralis major muscle samples from 10 individuals from each line-sex-age subgroup were obtained in a manner to prevent contraction. The muscle samples were dehydrated, cleared, embedded in paraffin, sectioned, incubated, and rehydrated before staining with hematoxylin and eosin. Representative sections were given a score by 4 individuals based on breast muscle morphology. The scores ranged from 1 (little extracellular matrix and indistinct muscle fibers) to 5 (large extracellular space and distinct muscle fibers). Scores from 2 to 4 were intermediate to these extremes. The pectoralis major muscle morphology scores were highest at 25 d of incubation and declined greatly at 1 wk of age. The scores increased from 1 to 4 wk of age and remained constant through 20 wk of age. Males had higher scores than females. In the current study, there was no significant difference between the E and RBC1 lines. Based on the results of 3 experiments (2 published and the present one) using the E and RBC1 lines, it appears that genetic increases in egg production may be associated with a slight reduction in pectoralis major muscle morphology scores at 16 wk of age.

(Co)Variance components and genetic parameters for economic traits in Iranian native fowls were estimated using multivariate animal model analysis with DFREML procedure. The data of four stations of native fowls breeding (Mazandaran: 49536, Esfahan: 23108, West Azarbaijan: 24890 and Fars: 30279) was containing records of cocks and hens collected during period of 1988 to 2006. The recorded traits were Body weight (at 8 weeks or 12 weeks), Age at first egg, egg number at 12 first weeks of production and mean egg weight between 28 to 32 weeks. The most estimated heritabilites, except egg number, were more than 0.20. The highest heritabilites for all traits were related to Fars station, whereas most heritabilites in West Azarbaijan were less than other stations. The heritability for egg number was estimated 0.099+/-0.018 for Esfahan to 0.322+/-0.012 for Fars. The estimated heritabilities of body weight were medium to high and varied from 0.228+/-0.014 for Esfahan to 0.548+/-0.014 for Fars, While, the heritabilities of mean egg weight were high and ranged from 0.223+/-0.021 for West Azarbaijan to 0.638+/-0.013 for Fars. The heritability for age at first egg was estimated 0.270+/-0.021 for Esfahan to 0.520+/-0.014 for Fars. The most estimated genetic correlations, except between Body weight and Egg weight and between age at first egg and egg weight, were negative. The direct genetic correlations between maturity age and egg number were high and negative, ranging from -0.384+/-0.033 to -0.987+/-0.003 for Mazandaran and Fars, respectively.

Expression levels of 33 high egg production candidate transcripts in Red-feather Taiwan country chickens (TCCs) were examined by quantitative reverse-transcription (RT) polymerase chain reactions (PCR) in this study. Candidate transcripts were previously identified from a L2-B (L2-subtract-B) hypothalamus/pituitary gland subtractive cDNA library. In this subtractive cDNA library, two divergently selected strains of TCCs, B and L2 were used. These two strains were originated from one single population and were further subjected (since 1982) to the selections of body weight/comb size (B) and eggs to 40wk of age (L2), respectively. Hypothalamuses and pituitary glands that sampled from Red-feather TCCs were previously grouped into high (Red-high; n=20) and low (Red-low; n=20) egg productions based on the rate of lay after 1st egg (hen-day laying rate; %). Rates of lay after 1st egg (mean+/-S.E.) in the Red-high and the Red-low subpopulations were 72.2+/-0.6 and 23.0+/-3.5, respectively (P<0.01). Quantitative RT-PCR validated that 25 candidate transcripts were significantly higher expressed in the Red-high than in the Red-low hens. These transcripts were ANP32A, BDH, CDC42, CNTN1, COMT, CPE, CTNNB1, DIO2, EIF4E, GARNL1, HSPCA, LAPTM4B, MBP, NAP1L4, NCAM1, PARK7, PCDHA@, PGDS, PLAG1, PRL, RAD21, SAR1A, SCG2, STMN1 and UFM1. Among these transcripts, 15 (79.0%), 13 (68.4%), and 12 (63.2%) genes were annotated to involve in cellular physiological process (GO:0050875), metabolism (GO:0008152) and cell communication (GO:0007154). Identified transcripts that related to high egg production are most active in focal adhesion, adherens junction, MAPK signaling, tight junction and cell adhesion pathways.

Suppression subtractive hybridization was used to detect differential expression of genes in the livers of laying and prelaying geese. Liver tissues from prelaying and laying geese were dissected for mRNA extraction. The cDNA, reverse transcribed from liver mRNA of prelaying geese, was subtracted from the cDNA generated from the laying geese (forward subtraction). Five hundred seventy-six clones with possible differentially expressed gene fragments were observed by forward subtraction hybridization. After differential screening using the reverse and forward subtraction cDNA, 164 clones were subjected to gene sequence determination and further analysis. Using Northern analysis, 5 known and 8 unknown genes were shown to be highly expressed in the livers of laying geese compared with prelaying geese. Vitellogenin I, apoVLDL-II, ethanolamine kinase, G-protein gamma-5 subunit, and leucyl-tRNA synthase were highly expressed in the livers of laying geese compared with that from the prelaying geese (P<0.05). The expression of these known genes suggests that their function in the liver of laying geese is primarily involved in lipid and lipoprotein metabolism. Several of these differentially expressed genes were found to be responsive to estrogen stimulation, confirming the involvement of these genes in the egg-laying function of the goose.

Despite its morphological similarity to the other species in the Drosophila melanogaster species complex, D. sechellia has evolved distinct physiological and behavioral adaptations to its host plant Morinda citrifolia, commonly known as Tahitian Noni. The odor of the ripe fruit of M. citrifolia originates from hexanoic and octanoic acid. D. sechellia is attracted to these two fatty acids, whereas the other species in the complex are repelled. Here, using interspecies hybrids between D. melanogaster deficiency mutants and D. sechellia, we showed that the Odorant-binding protein 57e (Obp57e) gene is involved in the behavioral difference between the species. D. melanogaster knock-out flies for Obp57e and Obp57d showed altered behavioral responses to hexanoic acid and octanoic acid. Furthermore, the introduction of Obp57d and Obp57e from D. simulans and D. sechellia shifted the oviposition site preference of D. melanogaster Obp57d/e(KO) flies to that of the original species, confirming the contribution of these genes to D. sechellia's specialization to M. citrifolia. Our finding of the genes involved in host-plant determination may lead to further understanding of mechanisms underlying taste perception, evolution of plant-herbivore interactions, and speciation.

Background: In insects and in mammals, male sperm and seminal fluid provide signaling factors that influence various aspects of female physiology and behavior to promote reproductive success and to compete with other males. It is less apparent how important such signaling is in the context of a self-fertile hermaphrodite species. We have addressed this question in the nematode Caenorhabditis elegans, which can reproduce either by hermaphrodite self-fertilization or by male-hermaphrodite mating., Results: We have studied the egg-laying defective mutant, egl-32, and found that the cellular basis of the egl-32 egg-laying phenotype is likely a defect in sperm. First, the time of egl-32 action coincides with the timing of spermatogenesis in the hermaphrodite. Second, egl-32 interacts with genes expressed in sperm. Third, mating experiments have revealed that wild-type sperm can rescue the egg-laying defect of egl-32 mutant animals. Most importantly, introduction of mutant egl-32 sperm into wild-type hermaphrodites or females is sufficient to induce an egg-laying defective phenotype., Conclusion: Previous work has revealed that C. elegans sperm release factors that stimulate oocyte maturation and ovulation. Here we describe evidence that sperm also promote egg laying, the release of embryos from the uterus.

The characterization of the follicular hierarchy and the expression of the mRNA for the inhibin/activin subunits was investigated in the follicles of 2 lines of turkey hens selected for over 40 generations for increased egg production (Egg line) or increased body weight (Growth line). The follicular hierarchies of 6 hens from the Egg and Growth lines were characterized in middle (45 wk of age) and late production (58 wk of age). Relative follicular weights for individual hierarchical follicles (>12 mm), pooled small yellow follicles (5 to 12 mm), and large white follicles (2 to 5 mm) were calculated. Total RNA was extracted for Northern blot analysis from individual granulosa cell layers of the F1 through F4 follicles, and from the combined granulosa and theca layers of small yellow follicles and large white follicles from an additional 6 hens from each genetic line. Egg line hens displayed a more distinct follicular size hierarchy than Growth line hens at 45 and 58 wk. Although total follicular weight relative to body size was greater at 45 and 58 wk of age for the Egg line hens than the Growth line hens, the total number of hierarchical follicles was greater in the Growth line hens at 45 and 58 wk of age. Expression of follistatin and the inhibin beta(B)-subunit was highest in nonhierarchical follicles, whereas the expression of the inhibin alpha- and beta(A)-subunits was highest in the hierarchical follicles. The inhibin alpha- and beta(A)-subunit mRNA expression pattern in the 4 largest follicles of the Growth line hens was not similar to the Egg line hens or characteristic of laying hens that have a high rate of egg production. The unusual inhibin subunit mRNA expression in the largest hierarchical follicles of the Growth line hens may account for their development of an abnormal follicular size hierarchy and for their poor egg production.

The heat shock response is a critical mechanism by which organisms buffer effects of variable and unpredictable environmental temperatures. Upregulation of heat shock proteins (Hsps) increases survival after exposure to stressful conditions in nature, although benefits of Hsp expression are often balanced by costs to growth and reproductive success. Hsp-assisted folding of variant polypeptides may prevent development of unfit phenotypes; thus, some differences in Hsp expression among natural populations of ectotherms may be due to interactions between enzyme variants (allozymes) and Hsps. In the Sierra willow leaf beetle Chrysomela aeneicollis, which lives in highly variable thermal habitats at the southern edge of their range in the Eastern Sierra Nevada, California, allele frequencies at the enzyme locus phosphoglucose isomerase (PGI) vary across a climatic latitudinal gradient. PGI allozymes differ in kinetic properties,and expression of a 70 kDa Hsp differs between populations, along elevation gradients,and among PGI genotypes. Differences in Hsp70 expression among PGI genotypes correspond to differences in thermal tolerance and traits important for reproductive success, such as running speed, survival and fecundity. Thus, differential Hsp expression among genotypes may allow functionally important genetic variation to persist, allowing populations to respond effectively to environmental change.

Random regression models (RR) have become a popular methodology for the genetic study of longitudinal data since the last decade. The first objective of the current study was to investigate the application of RR models for the genetic analysis of egg production in turkeys. Data collected from a heavy dam line were used to estimate genetic parameters with 2 RR models, one having second-order Legendre polynomials as regression over time (RR2) and another with third-order polynomials (RR3). The second objective was to benchmark the performance of RR models with more conventional methods, so genetic parameters were reestimated using a multitrait (MT) and a repeatability model. To assess the model efficiency of predicting missing values, a reduced data set was used, and for each model, the predicted values of the deleted records were compared with the true values. The RR models were further compared against each other by eliminating the last period and estimating the MS error of the predictions for both models. The repeatability model had the poorest performance in predicting missing values. Heritability estimates from RR2 and MT models were close, whereas the RR3 model estimates were different. Both RR models demonstrated better prediction ability than the MT model. However, when RR models were compared solely, the RR2 model resulted in the smallest MS error. The results indicated that the RR3 model overfitted the data, suggesting that the choice of the appropriate polynomial order requires careful consideration. The present study illustrated that the application of RR models for the genetic analysis of egg production in turkeys is not only feasible but also offers a high accuracy of prediction.

The underlying genetic basis of life-history traits in free-ranging animals is critical to the effects of selection on such traits, but logistical constraints mean that such data are rarely available. Our long-term ecological studies on free-ranging oviparous snakes (keelbacks, Tropidonophis mairii (Gray, 1841), Colubridae) on an Australian floodplain provide the first such data for any tropical reptile. All size-corrected reproductive traits (egg mass, clutch size, clutch mass and post-partum maternal mass) were moderately repeatable between pairs of clutches produced by 69 female snakes after intervals of 49-1152 days, perhaps because maternal body condition was similar between clutches. Parent-offspring regression of reproductive traits of 59 pairs of mothers and daughters revealed high heritability for egg mass (h2= 0.73, SE=0.24), whereas heritability for the other three traits was low (< 0.37). The estimated heritability of egg mass may be inflated by maternal effects such as differential allocation of yolk steroids to different-sized eggs. High heritability of egg size may be maintained (rather than eroded by stabilizing selection) because selection acts on a trait (hatchling size) that is determined by the interaction between egg size and incubation substrate rather than by egg size alone. Variation in clutch size was mainly because of environmental factors (h2=0.04), indicating that one component of the trade-off between egg size and clutch size is under much tighter genetic control than the other. Thus, the phenotypic trade-off between egg size and egg number in keelback snakes occurs because each female snake must allocate a finite amount of energy into eggs of a genetically determined size.

Genes encoding members of the p24 family of intracellular trafficking proteins are present throughout animal and plant lineages. However, very little is known about p24 developmental, spatial, or sex-specific expression patterns or how localized expression affects function. We investigated these problems in Drosophila melanogaster, which contains nine genes encoding p24 proteins. One of these genes, logjam (loj), is expressed in the adult female nervous system and ovaries and is essential for oviposition. Nervous system-specific expression of loj, but not ovary-specific expression, rescues the behavioral defect of mutants. The Loj protein localizes to punctate structures in the cellular cytoplasm. These structures colocalize with a marker specific to the intermediate compartment and cis-Golgi, consistent with experimental evidence from other systems suggesting that p24 proteins function in intracellular transport between the endoplasmic reticulum and Golgi. Our findings reveal that Drosophila p24 transcripts are developmentally and tissue-specifically expressed. CG31787 is male-specifically expressed gene that is present during the larval, pupal, and adult stages. Female CG9053 mRNA is limited to the head, whereas males express this gene widely. Together, our studies provide experimental evidence indicating that some p24 genes have sex-specific expression patterns and tissue- and sex-limited functions.

The random regression model (RRM) methodology was applied to the estimation of genetic parameters for cumulative egg numbers and monthly egg production in a broiler dam line. The data were extracted from records of a commercial dam line in 2001 to 2003. A total of 99,193 records from 6,475 hens and 9,111 pedigreed animals were used in the current study. The variance components were estimated using Gibbs sampling procedure. According to the Bayesian information criterion and Bayes factor, an RRM with Legendre polynomial of 2 orders for hatching groups and additive genetic effects and of 4 orders for permanent environmental effects was chosen as the optimal model for cumulative egg numbers in the broiler dam line. The heritability estimates of the cumulative egg numbers between wk 1 and 40 of production ranged from 0.16 to 0.54, whereas heritability estimates from wk 12 to 20 of production were moderate. The ratios of permanent environmental variance to phenotypic variance were large, indicating that the RRM could produce better estimates of additive genetic effects. The genetic and phenotypic correlations between cumulative egg numbers at different production weeks estimated with the optimal RRM were generally higher when the overlapping weeks were greater. In addition, genetic parameters for monthly egg production could also be obtained by the optimal RRM, and the heritability estimates ranged from 0.03 to 0.18. It was suggested that early selection based on cumulative egg numbers in the first 19 wk of production could effectively improve annual egg production in the broiler dam line.

1. The objective of this study was to investigate the strength of the genetic association between growth and reproduction traits in turkeys selected for body weight, conformation and egg production. 2. Two distinct populations but derived from the same heavy turkey female line and situated in different locations (UK and USA), were used to estimate genetic parameters using multivariate REML for the following traits: body weight at 14 (BW14), 19 (BW19) and 24 (BW24) weeks of age and total egg number (EGG). 3. A Box-Cox transformation was applied to egg production data to reduce the impact of non-normality. 4. The heritability estimates for each trait for the UK and USA populations, respectively, were: BW14 0.37 and 0.48; BW19 0.34 and 0.43; BW24 0.28 and 0.43; EGG 0.22 and 0.34. 5. The genetic correlation between the body weight at all ages and the total egg production was strongly negative, reaching a value of -0.75 for the UK and -0.55 for the USA population. 6. The comparison of our results with published estimates in turkeys suggests that the genetic correlation may get stronger in magnitude following selection for increased body weight. 7. This could arise from fixation during selection of genes favouring larger weights but with minimal effect on egg production, leaving the segregating genetic variation dominated by pleiotropic loci with antagonistic effects on the traits. 8. Thus, in order to avoid continued selection for body weight reducing egg production to a point where natural selection offsets selection gains, alternative selection strategies should be considered.

Breast muscle morphology was studied at 16 wk of age in a line (E) selected over 45 generations for increased egg production, its randombred control line (RBC1), and reciprocal crosses between the E and RBC1 lines. A sample of 10 birds per genetic group-sex subgroup was killed with restraint to prevent flapping of the wings. The skin was removed from the breast region and a sample of breast muscle was obtained in a manner to prevent contraction. The muscle samples were dehydrated, cleared, embedded in paraffin, sectioned, incubated, and rehydrated before staining with hematoxylin and eosin. Four sections from the same muscle from each bird were placed on a slide and the slides were viewed for muscle morphology characteristics with a microscope and digitally recorded. Five fields of each section were viewed. Representative sections of each bird were given a score by 4 individuals based on breast muscle morphology. The scores ranged from 1 (little extracellular matrix and indistinct muscle fibers) to 5 (large extracellular space and distinct muscle fibers). Scores from 2 to 4 were intermediate to these extremes. The data were analyzed for sexes separate and combined. The E line had lower breast muscle morphology scores than the RBC1 line for males and sexes combined, indicating additive genetic variation in the scores. Nonadditive genetic variation was not an important source of variation for breast muscle morphology scores based on the contrast of the average of the parental lines with the average of the reciprocal crosses for males, females, or sexes combined. In 5 of 6 possible comparisons, the breast muscle morphology scores of the reciprocal cross were not significantly different from the line of the dam in the reciprocal cross. The only exception was for the E sire x RBC1 dam cross based on the data for females, wherein the breast muscle morphology scores were higher in the cross than in the pure RBC1 line. The results of the current study confirm the maternal inheritance of breast muscle morphology scores at 16 wk of age that has been previously reported.

Background: Male-derived Sex-peptide (SP) elicits egg laying and rejection of courting males in mated Drosophila females. Little is known about the genes that specify the underlying neuronal circuits and mediate this switch in female sexual behavior., Results: Here we show that the egghead gene involved in glycosphingolipid biosynthesis provides an essential component to the SP response. We have isolated viable alleles of the vital egghead gene that abolish egghead expression from a distal promoter resulting in the absence of the largest transcript of this complex transcription unit. Temporally and spatially restricted expression of egghead revealed a requirement for egghead early in the development of apterous-expressing ventral nerve cord neurons to rescue the SP response. In viable egghead alleles, these ascending interneurons, three per abdominal and seven per thoracic hemisegment, fail to innervate the central brain. egghead expression in apterous neurons rescues neuronal targeting and the response to SP. Furthermore, neurotransmission in apterous neurons is required to elicit the SP response., Conclusion: Together with the former finding of SP binding to afferent nerves , these results suggest that SP-mediated modification of sensory input switches female sexual behavior from the virgin to the mated state.

To identify transcripts related to high egg production expressed specifically in the hypothalamus and pituitary gland of the chicken, two subtracted cDNA libraries were constructed. Two divergently selected strains of Taiwan Country Chickens (TCCs), B (sire line) and L2 (dam line) were used; they had originated from a single population and were further subjected (since 1982) to selection for egg production to 40 wk of age and body weight/comb size, respectively. A total of 324 and 370 clones were identified from the L2-B (L2-subtract-B) and the B-L2 subtracted cDNA libraries, respectively. After sequencing and annotation, 175 and 136 transcripts that represented 53 known and 65 unknown non-redundant sequences were characterized in the L2-B subtracted cDNA library. Quantitative reverse-transcription (RT)-PCR was used to screen the mRNA expression levels of 32 randomly selected transcripts in another 78 laying hens from five different strains. These strains included the two original strains (B and L2) used to construct the subtracted cDNA libraries and an additional three commercial strains, i.e., Black- and Red-feather TCCs and Single-Comb White Leghorn (WL) layer. The mRNA expression levels of 16 transcripts were significantly higher in the L2 than in the B strain, whereas the mRNA expression levels of nine transcripts, BDH, NCAM1, PCDHA@, PGDS, PLAG1, PRL, SAR1A, SCG2 and STMN2, were significantly higher in two high egg production strains, L2 and Single-Comb WL; this indicated their usefulness as molecular markers of high egg production.

Fertility is a physiological process of great importance underlying the dynamics of mosquito populations. In transgenesis, it is a prerequisite for the production of subsequent generations and a crucial parameter for evaluating efficiency. Yet, ongoing success in mosquito vector transformation is being severely affected by low embryo survivability. In the prospect of overcoming this impediment, we investigated the darkening/hardening process of the chorion, the effects of some parameters required for transgenesis on hatch success, and erratic hatching in Aedes albopictus, a species that has not yet been targeted for transformation. The eggs from this species, when placed in a moistened environment while whitish, become dark and yet still remain soft approximately 2 h 10 min postoviposition. Those reared in a high moisture environment hatched at a high rate compared with their counterparts submitted to a drier environment. Submission of eggs to p-nitrophenyl-p'-guanidino-benzoate, a substance known to delay the darkening/delay process, resulted in a hatch rate lower than that from eggs soaked in distilled water, which suggests a negative impact on viability. Heat-shock treatment did not taint embryo viability. Overall, eggs displayed a tolerance to an hour of heat shock at 39 degrees C but still hatched at a considerable rate after a 1 hr exposure to 42 degrees C. Hatching was erratic, with a high rate of hatching on the initial flooding and lower rates of hatching on subsequent floodings, all of which resulted cumulatively in considerable hatch success. Our results should serve as a useful reference for the production of both transgenic and laboratory strains of floodwater Aedes mosquitoes.

A total of 2,118 birds from 2 strains were allocated to 12 groups of 93 to 100 each in 2 time-separated replicates. The development of foot pad dermatitis (FPD) and hock burn (HB) were recorded weekly from d 8 to slaughter on a set sample of live animals (7 per group). In addition, feet and hocks of all birds were investigated at slaughter at either 4, 6 (fast-growing strain), 8, or 10 (slow-growing strain) wk of age. Lesions were scored for both the left and right foot and classified according to a scale from 1 (no lesion) to 9 (very severe lesions) for FPD and from 1 (no lesion) to 3 (very severe lesions) for HB. No FPD lesions and very few low-grade HB lesions were found in chickens from the slow-growing strain. In the fast-growing strain, the first signs of FPD and HB were seen in wk 2. The incidence of both types of lesions increased thereafter. Foot pad dermatitis was more frequent in females (49 vs. 36%, P < 0.05). Body weight did not affect FPD, but more HB were found at higher BW (P < 0.01). Egg weight influenced neither FPD nor HB. Variance and covariance components were analyzed using a multivariate animal model, in which scores for FPD and HB were transformed into logarithmic scale. The analyses were carried out using restricted maximum likelihood algorithm. Heritabilities were estimated to be 0.31 +/- 0.12 (SE) for FPD, 0.08 +/- 0.08 for HB, and 0.38 +/- 0.13 for BW. Genetic correlations among these traits were low and nonsignificant. Phenotypic correlation between BW and FPD was low and nonsignificant and between BW and HB was 0.17 +/- 0.05 (P < 0.01). The relative high heritability of FPD and the low genetic correlation to BW suggested that genetic selection against susceptibility to FPD should be possible without negative effects on BW gain.

Double-stranded RNA (dsRNA) gene interference is an efficient method to silence gene expression in a sequence specific manner. Here we show, that dsRNA targeting the allatostatin (AS)-A type (FGL/I/V-amide) gene of Gryllus bimaculatus (Ensifera, Gryllidae) and Spodoptera frugiperda (Lepidoptera, Noctuidae) injected into freshly moulted larvae or adult crickets and moths produced a rapid and long-lasting reduction in the mRNA levels in various tissues. The effect lasted up to 7 days. Following dsRNA injection, the juvenile hormone (JH) titers in the hemolymph were clearly raised in both species. AS-dsRNA injection induced a reduced body weight in larval and adult crickets and the imaginal moult was incomplete. Silencing allatostatin type-A expression also reduced the egg and testes development in crickets, and the oviposition rate was drastically diminished in both species.

Background: Egg production is of critical importance in birds not only for their reproduction but also for human consumption as the egg is a highly nutritive and balanced food. Consequently, laying in poultry has been improved through selection to increase the total number of eggs laid per hen. This number is the cumulative result of the oviposition, a cyclic and repeated process which leads to a pattern over time (the egg laying curve) which can be modelled and described individually. Unlike the total egg number which compounds all variations, the shape of the curve gives information on the different phases of egg laying, and its genetic analysis using molecular markers might contribute to understand better the underlying mechanisms. The purpose of this study was to perform the first QTL search for traits involved in shaping the egg laying curve, in an F2 experiment with 359 female Japanese quail., Results: Eight QTL were found on five autosomes, and six of them could be directly associated with egg production traits, although none was significant at the genome-wide level. One of them (on CJA13) had an effect on the first part of the laying curve, before the production peak. Another one (on CJA06) was related to the central part of the curve when laying is maintained at a high level, and the four others (on CJA05, CJA10 and CJA14) acted on the last part of the curve where persistency is determinant. The QTL for the central part of the curve was mapped at the same position on CJA06 than a genome-wide significant QTL for total egg number detected previously in the same F2., Conclusion: Despite its limited scope (number of microsatellites, size of the phenotypic data set), this work has shown that it was possible to use the individual egg laying data collected daily to find new QTL which affect the shape of the egg laying curve. Beyond the present results, this new approach could also be applied to longitudinal traits in other species, like growth and lactation in ruminants, for which good marker coverage of the genome and theoretical models with a biological significance are available.

If a novel, resistant host-plant genotype arises in the environment, insect populations utilising that host must be able to overcome that resistance in order that they can maintain their ability to feed on that host. The ability to evolve resistance to host-plant defences depends upon additive genetic variation in larval performance and adult host-choice preference. To investigate the potential of a generalist herbivore to respond to a novel resistant host, we estimated the heritability of larval performance in the noctuid moth, Helicoverpa armigera, on a resistant and a susceptible variety of the chickpea, Cicer arietinum, at two different life stages. Heritability estimates were higher for neonates than for third-instar larvae, suggesting that their ability to establish on plants could be key to the evolution of resistance in this species; however, further information regarding the nature of selection in the field would be required to confirm this prediction. There was no genetic correlation between larval performance and oviposition preference, indicating that female moths do not choose the most suitable plant for their offspring. We also found significant genotype by environment interactions for neonates (but not third-instar larvae), suggesting that the larval response to different plant genotypes is stage-specific in this species.

Estimates of genetic parameters for reproductive traits, live weight and body measurements were obtained using data from a pair-mated ostrich flock at Oudtshoorn in South Africa. Reproductive traits included total egg and chick production, along with hatchability percentage. Live weight, chest circumference and tail circumferences were recorded at the commencement and cessation of breeding. Heritability estimates (h(2)) were 0.23 for egg production, 0.20 for chick production, 0.10 for hatchability, 0.20 to 0.34 for live weight, 0.12 for chest circumference and 0.30 to 0.38 for tail circumference. Female permanent environmental effects (c(2)) amounted to 0.18 for egg production, 0.18 for chick production, 0.21 for hatchability, 0.32 to 0.36 for live weight and 0.23 to 0.32 for chest circumference. Service sire exerted significant effects only on hatchability (0.22) and subsequently chick production (0.09). Genetic correlations of reproductive traits with live weight were low to moderate, variable in sign, and did not differ significantly from zero. Correlations between live weight recorded at the beginning and end of the breeding season were unity for additive genetic and permanent environmental effects. Egg and chick production were highly correlated genetically and phenotypically, with the genetic correlation exceeding the theoretical limit. In unconstrained analyses, hatchability was positively related to chick production, including at the service sire level. Selection gains in the current flock and future generations are likely. No significant adverse relationships were found between live weight, body measurements and reproductive traits.

The effects of L-dihydroxyphenylalanine (L-DOPA) and 20-hydroxyecdysone (20E) were studied with respect to the content of dopamine (DA), intensity of the juvenile hormone (JH) degradation, and fecundity of the wildtype flies (Canton S) and JH-deficient apterous56f mutants (in young females, carrying this mutation, the levels of DA and 20E production were strongly increased). Fly feeding with L-DOPA proved to increase the level of DA in a dose-dependent manner and reduce JH degradation in 2-day-old females of both strains. Feeding with 20E produced the same effect. Treating the wild-type flies with 2.5 mg L-DOPA caused a 24-h delay in beginning of oviposition and reduction in fecundity throughout the experiment. An L-DOPA dose of 1 mg caused no such changes. An experimental increase in 20E titer led to reduced fecundity of the wild-type flies, though no delay in oviposition was observed. In mutant flies, an increase in DA and 20E levels accelerated beginning of oviposition and increased fecundity of young females, though the latter parameter was reduced in mature individuals. Thus, an increase in endogenous DA and 20E characteristic of young apterous56f females is assumed to be a compensatory response that leads to a higher JH titer and induction of vitellogenesis.

The correlated changes in egg production, egg quality, and feed efficiency (FE) due to selection for feather pecking (FP) were investigated by analyzing the data from an experiment including 2 divergently selected lines and a control line. The experiment was conducted with hens from 42 to 46 wk (hatch 1) and 39 to 43 wk (hatch 2) of age in the fifth generation of selection. The number of FP bouts per hour in the low FP line (LFP) was lower than the high FP line (HFP; 0.38 vs. 2.01), and total plumage score in line LFP was better than in line HFP (16.9 vs. 11.6). During the 4 wk, egg number and egg mass in line LFP were higher than those in HFP (24.4 vs. 18.3 and 1,223 vs. 1,132 g, respectively). On the other hand, line HFP had greater egg weight (60.7 vs. 59.2 g), albumen height (73.0 vs. 64.9 in Haugh units), shell thickness (38.1 vs. 37.0 mm), and yolk percentage (30.6 vs. 29.5%) than the LFP line. The control line was intermediate for those traits. The residual feed consumption (RFC) was highest in line HFP, lowest in line LFP, and intermediate in line C. Partial regressions of feed consumption (FC) on BW gain and egg mass were not significantly different among the 3 lines, whereas a significant difference in regression on metabolic BW (32.6 g/d in line LFP, 38.0 g/d in control line, and 43.4 g/d in line HFP) was observed. In addition, there was a negative regression of FC per day on plumage score (-1.73 g). The adjustment for plumage score accounted for 60% of the difference between regressions on metabolic BW in lines LFP and HFP. These results indicated that selection for FP has led to a change in egg production, egg quality, and FE. The better FE in line LFP resulted from a lower requirement for maintenance energy. The later was partly accounted for by a better plumage cover.

Genetic variance in characters under natural selection in natural populations determines the way those populations respond to that selection. Whether populations show temporal and/or spatial constancy in patterns of genetic variance and covariance is regularly considered, as this will determine whether selection responses are constant over space and time. Much less often considered is whether characters show differing amounts of genetic variance over the life-history of individuals. Such age-specific variation, if present, has important potential consequences for the force of natural selection and for understanding the causes of variation in quantitative characters. Using data from a long-term study of the mute swan Cygnus olor, we report the partitioning of phenotypic variance in timing of breeding (subject to strong natural selection) into component parts over 12 different age classes. We show that the additive genetic variance and heritability of this trait are strongly age-dependent, with higher additive genetic variance present in young and, particularly, old birds, but little evidence of any genetic variance for birds of intermediate ages. These results demonstrate that age can have a very important influence on the components of variation of characters in natural populations, and consequently that separate age classes cannot be assumed to be equivalent, either with respect to their evolutionary potential or response.

We studied the fertility of D. melanogaster females heterozygous for the dominant temperature sensitive mutation l(2)M167DTS, which exerts a recessive lethal effect at 25 degrees C, under the conditions of stable temperature regimes 25, 28, and 29 degrees C and changing regimes 25-->29 degrees C and 29-->25 degrees C. It was shown that inhibition of total activity of oogenesis due to a decreased number of functioning ovarioles is one of the mechanisms underlying the decreased fertility of l(2)M167DTS /+ females. Analysis of individual fertility of each female confirmed also the role of sterility as a component of fertility of the females. Sterilization was realized due both to full depletion of functioning ovarioles and disturbed mechanism of laying the mature eggs onto a substrate as a result of violation of the feedback blocking normal ovulation, which led to the breakdown of ovarioles and filling of the abdominal cavity with mature oocytes. A significant polymorphism of heterozygous females by their fertility was observed. The intensity of sterilization and mortality of l(2)M167DTS/+ females sharply increased at an elevated temperature (29 degrees C), especially at the pupal stage.

Genetic studies of behavior in the nematode Caenorhabditis elegans have provided an effective approach to investigate the molecular and cellular basis of nervous system function and development. Among the best studied behaviors is egg-laying, the process by which hermaphrodites deposit developing embryos into the environment. Egg-laying involves a simple motor program involving a small network of motorneurons and specialized smooth muscle cells, which is regulated by a variety of sensory stimuli. Analysis of egg-laying-defective mutants has provided insight into a number of conserved processes in nervous system development, including neurogenesis, cell migration, and synaptic patterning, as well as aspects of excitable cell signal transduction and neuromodulation.

Chicken prolactin (PRL) is a physiological candidate gene for egg production. The objective of the current research was to investigate the association of polymorphisms in the chicken PRL promoter region with egg production. Genotyping of 177 individuals from White Leghorn, Yangshan, Taihe Silkies, White Rock, and Nongdahe breeds for 6 single nucleotide polymorphisms (C-2402T, C-2161G, T-2101G, C-2062G, T-2054A, and G-2040A) and 1 24-bp indel (insertion-deletion) at the site of -358 of the chicken PRL gene revealed large breed differences in allelic frequencies for all but the T-2101G and T-2054A polymorphisms. An F2 population produced from Nongdahe x Taihe Silkies chickens consisted of 374 hens, which were recorded for egg production traits and genotyped for the above 7 polymorphisms. Marker-trait association analysis indicated that the 24-bp indel was associated with egg production (P < 0.01) and that H3 (C C T C T G) was the most advantageous haplotype for egg production.

Breast muscle morphology was studied at 8 and 16 wk of age in a line (E) selected over 44 generations for increased egg production and its randombred control line (RBC1). A sample of 20 birds per sex-line-age subgroup was killed with restraint to prevent flapping of the wings. The skin was removed from the breast region, and a sample of breast muscle was obtained in a manner to prevent contraction. The muscle samples were dehydrated, cleared, embedded in paraffin, sectioned, and incubated and rehydrated prior to staining with hematoxylin and eosin. Four sections from the same muscle from each bird were placed on a slide, and the slides were viewed for muscle morphological characteristics with a microscope and digitally recorded. Five fields of each section were viewed. Representative sections for each bird were given a score by 4 individuals based on breast muscle morphology. The scores ranged from 1 (little extracellular matrix and indistinct muscle fibers) to 5 (large extracellular space and distinct muscle fibers). Scores from 2 to 4 were intermediate to these extremes. Breast muscle morphology scores did not differ between lines or ages but there was a significant interaction between lines and ages. The scores increased in the RBC1 line from 8 to 16 wk of age, but the reverse was true for the E line. Scores were higher in males than females. The results of the present study suggest that selection for increased egg production in dam lines should not greatly influence breast muscle morphology in commercial turkeys.

Drugs that target the serotonergic system are the most commonly prescribed therapeutic agents and are used for treatment of a wide range of behavioral and neurological disorders. However, the mechanism of the drug action remain a conjecture. Here, we dissect the genetic targets of serotonin (5HT), the selective 5HT reuptake inhibitor (SSRI) fluoxetine (Prozac), the tricyclic antidepressant imipramine, and dopamine. Using the well-established serotonergic response in C. elegans egg-laying behavior as a paradigm, we show that action of fluoxetine and imipramine at the 5HT reuptake transporter (SERT) and at 5HT receptors are separable mechanisms. Even mutants completely lacking 5HT or SERT can partially respond to fluoxetine and imipramine. Furthermore, distinct mechanisms for each drug can be recognized to mediate these responses. Deletion of SER-1, a 5HT1 receptor, abolishes the response to 5HT but has only a minor effect on the response to imipramine and no effect on the response to fluoxetine. In contrast, deletion of SER-4, a 5HT2 receptor, confers significant resistance to imipramine while leaving the responses to 5HT or fluoxetine intact. Further, fluoxetine can stimulate egg laying via the Gq protein EGL-30, independent of SER-1, SER-4, or 5HT. We also show that dopamine antagonizes the 5HT action via the 5HT-gated ion channel MOD-1 signaling, suggesting that this channel activity couples 5HT and dopamine signaling. These results suggest that the actions of these drugs at specific receptor subtypes could determine their therapeutic efficacy. SSRIs and tricyclic antidepressants may regulate 5HT outputs independently of synaptic levels of 5HT.

We previously determined that certain recessive genes decrease female fecundity in a haplo-diploid spider mite, Stigmaeopsis miscanthi (Saito). However, whether the depression was caused by the breakdown of heterosis or the expression of deleterious genes retained in a population could not be determined, because we had started our inbreeding experiment from a mixture of two isolated populations. In order to answer this basic question, inbreeding effects on survival and fecundity were measured for eight small populations occurring far from the two initial populations. There was little depression of immature survival of inbred lineages in all populations. On the other hand, in two inbred lineages, both originating from the smallest populations, female oviposition decreased significantly with the increase of Wrights f-value, showing that mildly deleterious genes are actually retained even in natural populations of haplo-diploid organisms.

A mixed inheritance model, postulating a polygenic effect and differences between the 3 genotypes of a biallelic locus, was fitted separately to the data of 2 multigeneration selection lines and a control evolving from a common base population. Inferences about the model were drawn from the application of the Gibbs sampler. Body weight at 20 and 40 wk (BW20, BW40) and average egg weight to 40 wk (EW40) were included in the analyses. Significance of differences between posterior means of parameters was established by comparing their 95% highest probability density regions. Significant (P < 0.05) additive and dominance effects due to the genotypes at the major locus were found for all traits. The allele causing a lower trait value was the (partial) dominant one in all traits, leading to a negative dominance effect. The additive variance due to the major locus was also significant, i.e., greater than zero (P < 0.05) in all traits, whereas the dominance variance was only important for EW40. With the exception of the residual variances of one selection and the control line, no (P > 0.05) differences of posterior means of any parameter could be observed between lines. No significant genotypic or polygenic selection response was found for BW40. On the contrary, both genetic responses were found significant for EW40 in the selected lines, but not in the control. No differences (P > 0.05) between lines could be observed for the derived frequencies of the allele causing the higher trait value and the frequencies of one homozygote and the heterozygote genotypes at the major locus. The detection of a major locus with relatively modest effect confirmed that this type of analysis with data from selected lines was indeed powerful.

Ca(2+)/calmodulin-dependent calcineurin has been shown to have important roles in various Ca(2+) signaling pathways. We have previously reported that cnb-1(jh103) mutants, null mutants of a regulatory B subunit, displayed pleiotropic defects including uncoordinated movement and delayed egg laying in Caenorhabditis elegans. Interestingly, gain-of-function mutants of a catalytic A subunit showed exactly opposite phenotypes to those of cnb-1(null) mutants providing an excellent genetic model to define calcium-mediated signaling pathway at the organism level. Furthermore, calcineurin is also important for normal cuticle formation, which is required for maintenance of normal body size in C.elegans. Genetic interactions between tax-6 and several mutants including egl-30 and egl-10, which are known to be involved in G-protein signaling pathways suggest that calcineurin indeed regulates locomotion and serotonin-mediated egg laying through goa-1(Goalpha) and egl-30(Gqalpha). Our results indicate that, along with CaMKII, calcineurin regulates G-protein-coupled phosphorylation signaling pathways in C.elegans.

(1) The study was conducted to estimate the heritability, genetic correlations and breeding values of laying hens based on individual records and group mean records. (2) Records of two pure lines from a commercial breeding programme of White Leghorns from three generations housed in single cages and in group cages were used. A total of 8483 and 8817 individual records of lines A and D, respectively, and a total of 1358 (line A) and 1161 (line D) group mean records were analysed. (3) An animal model using Restricted Maximum Likelihood (REML) was used to estimate variance components of individual records. Group mean records were analysed using the sire model, taking heterogeneity of error variance and correlated residual effects into account. Breeding values of sires were estimated based on the BLUP method using a multivariate sire model. Spearman Rank correlations were used to compare sire breeding values estimated from individual records and from group mean records. The traits studied were monthly egg production, cumulative production and egg weight. (4) Heritability estimates based on individual records were higher than from group mean records. Heritabilities for cumulative production records were higher than for monthly production, based on individual as well as group mean records. The estimates of genetic correlations between monthly egg production and cumulative production were moderate to high. Egg production and egg weight recorded individually were highly genetically correlated with those recorded on group means. Sire breeding values estimated from individual records showed high correlations with those from group mean records. (5) Differences in the ranking of sire breeding values estimated from individual vs group mean records were negligible, indicating that no genotype x environment interaction exists. Selection based on individual performance records of laying hens housed in single cages could give a good response on performance of laying hens housed in group cages. Cumulative egg production over periods 1 to 6 is the best trait for the selection programme.

In Drosophila melanogaster, seminal fluid proteins influence several components of female physiology and behavior, including re-mating rates, ovulation and oviposition, and sperm use. It is well-known that female flies are not simply passive vessels and that female-mediated interactions with male products are important to female (and thus male) reproductive success. While the population genetics, molecular evolution and physiological effects of seminal fluid proteins have been examined, the genetics and evolution of the female side of these post-mating interactions is unexplored in spite of work showing that female genotype and female-by-male genotype interactions are important determinants of sperm competition outcomes. Here we use microarrays to identify candidate genes involved in the female side of post-mating sexual interactions. We report the results of a whole-genome oligonucleotide chip experiment that reveals 23 genes differentially expressed between virgin females exposed and unexposed to courting males, and 38 genes differentially expressed between virgin and recently mated females. Immune related genes are overrepresented among the mating-influenced candidates. We use quantitative reverse-transcriptase PCR to independently assess gene expression changes for roughly half of the mating-affected candidate genes.

Caenorhabditis elegans egg-laying behavior is inhibited by neurotransmitter signaling through the neural G-protein Galpha(o) and serves as a model for analyzing Galpha(o) signaling. Mutations that alter egg-laying frequency have identified genes encoding a number of signaling proteins that act with Galpha(o), but the receptors that activate Galpha(o) remain mostly uncharacterized. To further analyze Galpha(o) signaling, we cloned the egl-47 gene, which was identified by two dominant mutations that severely inhibit egg laying. egl-47 encodes two orphan G-protein-coupled receptor isoforms, which share all seven transmembrane domains but have different extracellular N termini. Both dominant mutations change the same alanine to valine in the sixth transmembrane domain, resulting in constitutively activated receptors. Deletion of the egl-47 gene caused no detectable egg-laying defects, suggesting that EGL-47 functions redundantly, or it inhibits egg laying under specific circumstances as yet unidentified. Using promoter::green fluorescent protein transgenes, we found that EGL-47 is expressed in a number of neurons, including the hermaphrodite-specific neurons (HSNs) that innervate the egg-laying muscles to stimulate contraction. Transgenic expression of constitutively active EGL-47 or constitutively active Galpha(o) specifically in the HSNs was sufficient to inhibit egg-laying behavior. Our results suggest that EGL-47 regulates egg laying by activating Galpha(o) in the HSN motor neurons to inhibit their activity. Because several neurotransmitters act through Galpha(o) to inhibit HSN function, it appears that loss of any one receptor, such as EGL-47, causes only mild defects. Galpha(o) apparently integrates signaling from multiple receptors in the HSNs, including EGL-47, to set the frequency of egg-laying behavior.

Few studies have examined the genetic architecture of population differences in behaviour and its implications for population differentiation and adaptation. Even fewer have examined whether differences in genetic architecture depend on the environment in which organisms are reared or tested. We examined the genetic basis of differences in oviposition preference and egg dispersion between Asian (SI) and African (BF) populations of the seed beetle, Callosobruchus maculatus. We reared and tested females on each of two host legumes (cowpea and mung bean). The two populations differed in mean oviposition preference (BF females preferred cowpea seeds more strongly than did SI females) and egg dispersion (SI females distributed eggs more uniformly among seeds than did BF females). Observations of hybrid and backcross individuals indicated that only the population difference in oviposition preference could be explained by complete additivity, whereas substantial dominance and epistasis contributed to the differences in egg dispersion. Both rearing host and test host affected the relative magnitude of population differences in egg dispersion and the composite genetic effects. Our results thus demonstrate that the relative influence of epistasis and dominance on the behaviour of hybrids depends on the behaviour measured and that different aspects of insect oviposition are under different genetic control. In addition, the observed effect of rearing host and oviposition host on the relative importance of dominance and epistasis indicates that the genetic basis of population differences depends on the environment in which genes are expressed.

The objective of the current study was to investigate different approaches for handling missing records and to develop and implement a multivariate longitudinal mixed model for the genetic evaluation of male and female fertility and hatchability in chickens. The traits recorded on a weekly basis were eggs set (E), percentage fertility (F), and percentage hatch of fertile eggs (H). Three approaches for handling missing records were investigated: 1) all records with zero weekly laid eggs were removed and remaining records with missing F and H were predicted (M1); 2) missing records, including zero weekly laid eggs, were assumed known and equal to zero (M2); and 3) zero weekly laid eggs were assumed as a valid record and missing F and H were predicted (M3). A longitudinal mixed model was used for the multiple trait analysis of E, F, and H. Fixed effects included week-flock, age of service sire (rooster in the pen at data collection), and age of hen. Unrelated service sire, additive hen, permanent environmental, and the residual term were included as random effects. Heritability estimates ranged from 0.06 to 0.13 for E, F, and H. Heritability estimates of F and H were overestimated using M2. Correlations among the 3 traits were highest using M2 and lowest using M1. Pearson correlations indicated that reranking of birds and service sires could occur when using M1. Therefore, M1 should not be used for the analysis of longitudinal data of fertility and hatchability in chickens. Furthermore, M3 seems to be the most ideal method for handling missing records.

Endocrine factors, such as steroid hormones and growth factors, regulate egg productivity in terms of the quantity of egg production, egg weight, sexual maturity, and the number of small yellow follicles (SYF). Insulin-like growth factors (IGF) are involved in the regulation of ovulation rate and ovarian follicular development in chickens, and a relationship between IGF-I genotype and egg weight has been reported. However, the effect of IGF on egg productivity in Korean Native Ogol chickens (KNOC) has been little studied. Therefore, this study was conducted to identify the relationship among endocrine factors (IGF-I, IGF-II, estradiol, and progesterone), IGF-I genotypes, and egg productivity. Frequencies of IGF-I genotypes (AA, AB, BB) were 17.3, 26.9, and 55.8%, respectively, within a population. When compared with the IGF-I genotypes, the AB genotype had the highest serum levels of estradiol and progesterone at 40 and 30 wk of age, respectively; the highest IGF-II concentration in F1 follicles at 60 wk; and was positively associated with the number of SYF at 60 wk. The results showed that the A allele was associated with a higher IGF-II expression in the follicles and stimulated the development of follicles, indicating a positive association of the A allele with egg production and the number of SYF. Therefore, these results suggest that there is a possibility of IGF-I genotypes acting as a genetic marker for egg productivity of KNOC.

A line (E) of turkeys selected long term (40 generations) for increased egg production was reciprocally crossed with a commercial dam line (BD). The BD line was larger and had better conformation than the E line, but the E line laid more eggs than the BD line. Heterosis was negative and significant for BW at 8, 16, and 20 wk of age (both sexes) and at 50% production (females only). Values for heterosis ranged from -3.1 to -5.5%. Negative heterosis was observed for breast width at 16 wk of age (10.8 and 3.0% for males and females, respectively). Positive heterosis values of 9.2, 10.2, and 11.3% were observed for egg production when based on 84, 120, and 180 d, respectively. Heterosis (-8.2%) was significant for rate of response to stimulatory lighting of 14 h light per day (days from stimulatory lighting to production of first egg). Based on data for a 180-d production period, heterosis was observed in average clutch length (12.6%) and rate of lay [number of eggs laid: (180 - total days broody)] (8.2%) but not in total days lost from broodiness or the effective length of the laying period (180 minus days lost in periods of 5 or more consecutive days at the end of the laying period). The present results along with those in the literature suggest that more heterosis in egg production traits might be expected in crosses of lines exhibiting extreme differences in BW and body conformation. The negative heterosis in BW in the BD and E reciprocal crosses reduces the commercial importance of such a cross to improve egg production.

1. Two experimental lines of dwarf brown-egg layers selected on clutch length were reciprocally crossed. In total, 288 hens, from three genotypes: L1, purebred normally feathered (121 hens), F1, crossbred and heterozygous for the NA mutation (99 hens) or L2, purebred homozygous for NA (68 hens) were housed in three climatic rooms at 22 degrees C and three climatic rooms at 32 degrees C. 2. Body weight, daily egg production records, feed intake and some anatomical and physiological traits were recorded. Canonical discriminant analysis was used to examine the relationships among all measured traits and to compare the experimental groups as defined by genotype and temperature. 3. Heterosis effects were observed on body weight, feed intake, egg mass and some anatomical traits at 22 degrees C, but were negligible for most of the traits measured at 32 degrees C except for body weight at 34 weeks, clutch length and some anatomical traits. 4. Genotype by temperature interactions were observed for egg production, egg mass and feed intake. The temperature stress was severe, with a marked decrease in egg production. The naked neck gene could limit the negative effect of long-term heat stress. Egg weight was increased by the NA gene, as usually observed in layers. 5. The first three canonical variates explained altogether 97.4% of the variance. The first canonical variate was associated almost exclusively with ambient temperature. The second was associated with genotype. The third was associated with heterozygous genotype for NA mutation and genotype by temperature interaction. Stepwise discriminant analysis indicated that 12 traits out of 20 were effective at detecting the differences among the genotype and temperature combinations.

1. Genetic parameters in the base population of a closed experimental strain of Muscovy ducks, selected for body weight at 10 weeks of age, were estimated from data in 8 successive generations, for the following traits: age at first egg (AGE1EGG), total number of eggs laid at 40 and 52 weeks of age (NEGG40 and NEGG52), number of eggs laid during 15 and 22 weeks in the first laying cycle (NEGG15W and NEGG22W), and their Box-Cox transformed data. 2. The method of multi-trait restricted maximum likelihood with an animal model was used to estimate genetic parameters. Only the results obtained with non-transformed data are shown. 3. Heritability estimates for laying performance showed moderate values, increasing little with age: 0.20+/-0.03 (AGE1EGG), 0.23+/-0.03 (NEGG40), 0.27+/-0.03 (NEGG52), 0.20+/-0.03 (NEGG15W), and 0.22+/-0.03 (NEGG22W). 4. Genetic correlations between laying traits were high. Genetic correlation between AGE1EGG and egg number was negative, it was positive between total numbers of eggs at 40 and 52 weeks and egg numbers in the first laying cycle. 5. Body weight at 10 weeks of age exhibited positive genetic correlations (0.46+/-0.06) with age at first egg and negative with egg production traits (-0.28+/-0.06 to -0.41+/-0.06). 6. The cumulated predicted genetic gains, after 7 generations of selection, expressed per genetic standard deviation unit (sigma(g)) were 0.06 sigma(g), 0.07 sigma(g), 0.17 sigma(g), 0.23 sigma(g), and 0.25 sigma(g) for AGE1EGG, NEGG40, NEGG52, NEGG15W, and NEGG22W, respectively. 7. Selecting Muscovy ducks to improve laying in Taiwanese climatic conditions would be possible using the number of eggs laid up to 52 weeks of age as the selection criterion. Because unintended selection effects for laying traits were present, the selection experiment for body weight at 10 weeks of age was not antagonistic with laying traits.

1. A study was conducted to investigate the effects of several vitamins and trace elements chickens and in chickens experimentally infected with malabsorption syndrome (MAS). 2. Vitamins and trace minerals in feed were varied. Breeders received either a basal amount of vitamins and trace minerals (low mix) or an increased amount (high mix). Their progeny also received either a low mix or a high mix. Effects of different breeder and broiler mix combinations on broiler performance, heamatology, spleen weight and humoral response were examined in control chickens. The effects of the different feeds and breeder, broiler combinations at the severity and recovery of MAS infection were also studied. 3. In general, the immune system can be stimulated by addition of vitamins and trace minerals, without affecting the growth potential of the controls. The number of leukocytes increased on d 1 in the broilers descended from breeders receiving high mix. The response to Newcastle disease virus boost was affected by the different amount of vitamins. 4. When breeders received a high mix the number of infiltrating polymorphonuclear leukocytes in the intestine was higher compared with breeders receiving basal amounts of minerals and vitamins. Also the recovery rate of intestinal lesions, cystic crypts of Lieberkühn and villus atrophy, as observed by histopathology, was faster in the groups where the breeders received high mix.

Drosophila sechellia, an island endemic that specializes on a single host plant, has a lower rate of egg production than its generalist sister species D. melanogaster, D. simulans, and D. mauritiana. Earlier work showed that part of this difference in egg production was due to a reduction in the number of ovarioles in D. sechellia relative to its sister species. Here, I extend this earlier work by genetically analyzing the difference in egg production between D. sechellia and D. simulans. In all, 10 genetic markers were used in several interspecific backcrosses to identify chromosome regions that affected the rate of egg production. While previously mapped factors affecting ovariole number appear to impact the rate of egg production, new, non-ovariole factors were also identified. Overall, the difference in egg production between D. sechellia and D. simulans appears to be a polygenic trait. The relationship between these factors and genes involved the adaptation of D. sechellia to its host plant is not yet clear. The data are consistent with the hypothesis that decline in egg production is, in part, a negative pleiotropic effect of genetic changes required for host specialization in D. sechellia, although finer-scale genetic analysis of both traits is needed to truly test this hypothesis.

Markers of alleles for three physiological candidate genes for reproductive traits, growth hormone (GHR), gonadotropin-releasing hormone receptor (GNRHR) and neuropeptide Y (NPY) were assessed for the association with the total egg production, number of double-yolked eggs and age at first egg in a single generation of a broiler breeder (Gallus gallus) pedigree dam line. Single-nucleotide polymorphisms and deletions were detected in the GHR, GNRHR and NPY genes. Genotypes were identified using a PCR-RFLP assay. The frequency of restriction enzyme+/-alleles in the population was for GHR 0.68 (NspI-) and 0.32 (NspI+), for NPY 0.78 (DraI+) and 0.22 (DraI-) and for GNRHR 0.54 (Bpu1102I+) and 0.46 (Bpu1102I-). Trait data from a total of 772 hens in 67 sire families from one generation of the pedigree dam line were recorded. However, the analysis used only the offspring of heterozygous sires to reduce the influence of selection and genetic background (n=33 sire families for GHR; n=14 sire families for NPY; n=36 sire families for GNRHR). A dominance effect of NPY on age at first egg and an additive effect of GNRHR on the number of double-yolked eggs were found (P<0.05).

Quadratic partial regression coefficients were estimated for the inbreeding level on five performance traits (body weight, average egg weight, age at first egg, percentage of fertilized eggs, and hatchability of set eggs) of two strains of laying hens. Data on 5631 of H77 layers and 3563 of N88 layers from nine consecutive generations were analysed. Only dams were accounted for. Partial regression coefficients were estimated by REML with a single-trait animal model, which included fixed effects (generation and hatching period) and random effects (additive genetic and error effects). The mean inbreeding level was 0.87% in strain H77 and 1.08% in strain N88. The inbreeding effects were analysed based on the quadratic partial regression equations. A slight inbreeding depression was found for all the traits analysed in N88. In strain H77, negative effects of inbreeding were only noted for body weight and average egg weight. The small inbreeding effects shown here resulted from a relatively low level of homozygosity in the populations studied. The strains were found to differ in the effects of inbreeding. It is worth pointing out that differences were noted both between the inbreeding depression estimated from the partial linear regression equation and the quadratic partial regression equation, as well as different inbreeding levels.

The aim of this work was to study fear responses and their relation to production traits in red junglefowl ( Gallus gallus spp.), White Leghorn ( Gallus domesticus ), and their F2-progeny. Quantitative trait locus (QTL) analyses were performed for behavioral traits to gain information about possible genetic links between fear-related behaviors and production. Four behavioral tests were performed that induce different levels of acute fear (open field [OF], exposure to a novel object, tonic immobility, and restraint). Production traits, that is, egg production, sexual maturity (in females), food intake, and growth, were measured individually. A genome scan using 105 microsatellite markers was carried out to identify QTLs controlling the traits studied. In the OF and novel object tests (NO), Leghorns showed less fear behavior than junglefowl, whereas junglefowl behaved less fearfully in the tonic immobility test (TI) and were more active in the restraint test. In the F2 progeny, only weak phenotypic associations were found between production traits and fear behavior. A significant QTL for TI duration was found on chromosome 1 that coincided with a QTL for egg weight and growth in the same animals. Another QTL for NO in males coincided with another major growth QTL. These two known growth QTLs affected a wide range of reactions in different tests. Several other significant and suggestive QTLs for behavioral traits related to fear were found. These QTLs did not coincide with QTLs for production traits, indicating that these fear variables may not be genetically linked to the production traits we measured here. The results show that loci affecting important production traits are located in the same chromosomal region as loci affecting different fear-related behaviors.