Quantitative trait loci analysis of egg and meat production traits in a red junglefowlxWhite Leghorn cross

Egg and production traits are of considerable economic importance in chickens. Using a White Leghorn x red junglefowl F(2) intercross, standard production measures of liver weight and colour, egg size, eggshell thickness, egg taste and meat quality were taken. A total of 160 markers covering 29 autosomes and the Z chromosome were genotyped on 175-243 individuals, depending on the trait under consideration. A total of nine significant quantitative trait loci (QTL) and three suggestive QTL were found on chicken chromosomes 1, 2, 4, 5, 7, 8, 10, 12, E47W24 and E22C19W28.     

Selection response for part period egg number and egg mass in chickens — a comparison

Summary Two sublines from each of four flocks of White Leghorn were subjected to two cycles of selection for part year egg number and part year egg mass. A family index (combined selection) was the selection criterion for each of the two traits. The generation means of an unselected pedigreed randombred control, bred and maintained along with the selected sub-lines, were used for correcting short term environmental trends. The sublines selected for a common selection criterion were considered as replicates. The control corrected generation means, when averaged over replicates, gave the mean direct and correlated responses for the selected and different unselected traits. The average genetic change per generation was 2.16 eggs in egg number selected sublines and 146 g of egg mass in egg mass selected sublines. The direct response marginally exceeded the correlated response for both part period egg number and egg mass seen in the corresponding sublines. Except for egg weight the correlated responses for different unselected traits were in the same direction in both egg number and egg mass selected sublines. While the egg weight in egg number lines did not change, its response was positive in egg mass selected lines. A comparison between the lines revealed that the egg mass selected lines matured later and laid heavier but slightly less numerous eggs than the egg number selected sub-lines.     

杂交小麦制种研究现状及展望

利用杂种优势对提高小麦单产具有重要作用,杂交小麦制种是小麦种业未来发展的重要方向之一。目前,小麦在强优势杂交组合选配方面取得较大进步。由于缺乏优异高异交结实率的制种亲本资源和高产高效杂交制种体系,导致大面积制种效率低。因此,探究杂交制种技术体系进展、亲本种质资源改良和生产流程标准化等方面的研究现状,将有利于对杂交制种发展瓶颈和未来发展方向等问题的整体把握。综述杂交小麦制种技术的影响因素,并通过商业化大田杂交作物与新型杂交小麦比较,对杂交小麦快速商业化等方面提出建议,对其发展趋势进行展望。     

Vigour-related traits and immunity in hybrids of evolutionary divergent cyprinoid species: advantages of hybrid heterosis?

Hybrid advantage, described as the superiority of hybrids in some traits over their parents and termed the “heterosis effect,” is widely documented in the case of reciprocal crosses of parental species (i.e., hybrids representing the F1 generation). In fish, high survival, fast growth and better health status have been widely documented in F1 hybrids. Nonetheless, the effects of interspecific hybridization on vigour, physiology and immunity-related traits in fish are largely unknown, especially concerning native systems of coexisting parental and hybrid genomes in the same habitat. The present study examined the potential physiological and immune aspects of hybrid heterosis by comparing condition status (measured especially by indexes), haematological profile, glucose concentration and selected parameters of non-specific and specific immunity between the evolutionarily divergent non-congeneric cyprinoid species Abramis brama and Rutilus rutilus and their hybrids representing the F1 generation, all of them caught in nature. Clear differences were documented for vigour-related, physiological and immune parameters between the two divergent species. Hybrids generally tended to express intermediate characters of the measured traits, likely generated by the evolutionary divergence of the hybridizing species; nonetheless, for some traits, hybrids exhibited a character that was more similar to one parental species than to the other. This was interpreted as the heterozygote advantage for F1 hybrids. It is suggested that a maternally inherited genetic background may potentially influence the expression of some branches of non-specific immunity or other aspects related to the fish health status.     

SSR heterogenic patterns of parents for marking and predicting heterosis in rice breeding

The most important concerns of hybrid rice breeders are selection of donors to improve parental lines and prediction of hybrid performance. In this study, SSR molecular marker technology and a half-diallel method were used to address these related hybrid production issues. The results show that genetic diversity among the parental lines is certainly related to heterosis. The heterozygosity of each parental pair is significantly associated with the general combining ability, not with the specific combining ability. However, neither genetic diversity nor heterozygosity is a good indicator for predicting heterosis. From these results, it is suggested that donors for improving parents of hybrids be selected from the improved inbred lines by conventional breeding programs. In this investigation, we also discovered that four favorable alleles and six favorable heterogenic patterns on the parental lines significantly contribute to the heterosis of their hybrids in grain yield, whereas six unfavorable alleles and six unfavorable heterogenic patterns significantly reduce heterosis. These noticeable findings could be, in practice, useful for hybrid rice breeding programs with SSR marker-assisted selection. It is suggested that the optimal combinations with the superior grain yield could be bred out by assembling those favorable alleles into their parental lines and by removing the unfavorable alleles from the parental lines. This study also indicates that there is still a great heterosis potential to be exploited in indica/indica hybrids by the same strategy. In indica/japonica hybrid breeding programs, it may also be important to remove unfavorable alleles rather than broaden genetic diversity or heterozygosity of the parents.     

Effects of cold on CO2 exchange in winter rape leaves

A viable wheat hybrid intermediate of the same height as the parents was obtained by crossing the female parent of tall variety NP4 with the male parent of the dwarf variety HD2160. Seeds of the hybrid and its parents were germinated and their growth pattern as well as the activities of peroxidase, indolyl-3-acetic acid oxidase and amylase in extracts made from them were studied at the early seedling stages i.e. up to 96 h.
A positive correlation existed between the length of the axis at the early seedling stage and at mature plant height as far as the parental varieties are concerned but no such correlation was observed with the hybrid. Growth of the hybrid seedlings was less than of its parents. Light appeared to stimulate the longitudinal growth of the axis to different extents in the parents and hybrid. Higher activities of peroxidase, indolyl-3-acetic acid oxidase and amylase were observed in the hybrid as compared to both of its parents. Lethal wheat hybrid also exhibits increased activities of amylase, indolyl-3-acetic acid oxidase and peroxidase. Therefore, it appears that seedling growth and enzyme activities at the seedling stage are not always correlated with hybrid vigour.     

Short allele dominance as a source of heterozygote deficiency at microsatellite loci: experimental evidence at the dinucleotide locus Gv1CT in Gracilaria gracilis (Rhodophyta)

In this study, we compared the genotypes obtained at a microsatellite locus using two methods of amplification and detection of variation in a set of individuals belonging to the red alga haplo-diploid species, Gracilaria gracilis . The methods varied in their capacity to detect longer alleles in heterozygotes, resulting in an apparent heterozygote deficiency. We attributed this bias in favour of short alleles to competition leading to the preferential amplification of shorter alleles (short allele dominance). To test this hypothesis, we created artificial heterozygotes (mixtures of two haploid DNA samples) and showed that long alleles already less intense than short alleles, 'suffer' more from being in association.     

不同品牌柴鸡蛋的氨基酸分析与评价

本次实验选取了圣景园、天嘉湖、今珠、富兴四种不同品牌的柴鸡蛋,对其蛋清和蛋黄中的粗蛋白含量以及氨基酸组成和含量进行了测定和分析,通过氨基酸比值系数法对其营养价值进行了评定。结果表明,这四种不同品牌的柴鸡蛋氨基酸含量丰富,种类齐全,组成比例合理,其中,今珠品牌的柴鸡蛋不论是粗蛋白含量,还是氨基酸比值系数分均高于其他几种柴鸡蛋,评分达到了82.34,说明其所含的必需氨基酸的含量及相互间的组成比例与人体的需求更加接近,营养价值更高。同时也说明柴鸡蛋营养价值较高,具有广阔的市场开发和利用前景。     

A Study of <Emphasis Type="Italic">in vitro</Emphasis> Regeneration in Relation to Doses of Growth Regulators in Hybrids of Upland Cotton

The frequency of in vitro callus induction and plant regeneration is influenced by several factors, including composition of culture medium, explant source, and the genotype. Crosses between regenerable and non-regenerable upland cotton cultivars were evaluated for hybrid vigour towards regeneration responses, which is consequential in recalcitrant crop species like cotton where regeneration is limited only to a few cultivars. The results indicated that regenerable and non-regenerable parental cultivars had similar potential of producing callus, but differed in producing callus weight and embryogenic calli. Mean performance of crosses, regarding callus induction, callus weight, callus growth rate, percent embryo induction, and percentage of germinating embryos, deviated considerably from the performance of their parents, signifying the presence of hybrid vigour for the expression of these traits. Magnitude of hybrid vigour varied across hormonal levels. Genetic component was evident for all the traits although of lower magnitude. The results indicated that genetic component in the phenotypic expression of callus growth, percentages of embryo induction and germinating embryos was higher than that of callus induction, callus weight and percentage of embryogenic calli. Hormonal concentration in the media had affect on the degree of gene expression responsible for regeneration in upland cotton. Over, partial- and additive-dominance types of gene effects were apparent in the expression of these traits. Genotype × growth regulator level interaction caused considerable variation in the expression of regeneration responses, suggesting that determination of specific level of growth regulator concentration in the medium was necessary for a particular genotype to obtain optimum response. Genotype × explant source interaction was, however, relatively less important. Differences among genotypes for percent embryo induction were clearly evident.     

Transgressive aggression in Sceloporus hybrids confers fitness through advantages in male agonistic encounters

1.  We investigated agonistic behaviour and associated characteristics of Sceloporus woodi (Florida scrub lizard), Sceloporus undulatus (Eastern fence lizard) and their hybrids using staged territorial encounters.
2.  These Sceloporus hybrids exhibit transgressive aggression and transgressive head-girth relative to the parental species and the transgressive aggression was specifically associated with an advantage in agonistic encounters. Our results suggest a hybrid advantage in natural habitats when defending and invading territories against either parental species.
3.  We further analysed general advantages in agonistic encounters across the entire three-group system to elucidate characteristics that may be advantageous under specific circumstances. Individuals with larger body size (SVL) and greater aggression had an overall advantage in agonistic encounters; however, smaller individuals could win when slightly more aggressive and fatter, and less aggressive individuals could win when slightly larger, especially with greater head-girth.
4.  The extreme hybrid phenotypes likely occurred through transgressive segregation, which has been implicated as a process through which homoploid, hybrid speciation can occur. Some form of ecological divergence is necessary, however, to impede parental gene flow. Our data suggest that ecological divergence could manifest in territorial species through transgressive aggression.     

Polychromatisme et polymorphisme biochimique chez cinq espèces de phasianidés

A correspondence between egg shell polychromatism and polymorphism of egg white proteins is presented and discussed in five related species of Phasianidae: Coturnix coturnix japonica, Lophortyx californica, Perdix perdix, Alectoris rufa and Phasianus colchicus.