GENETIC MODELS AND ANALYSIS METHODS FOR SEX-LINKED AND MATERNAL GENE EFFECTS

Genetic models are proposed for analyzing sex-linked and maternal effects as well as autosomal gene effects.For the model with no genotype×environment interaction,the total genetic effect is partitioned into direct additive （A）,direct dominance （D）,sexlinked （L）,maternal additive （Am） and maternal dominance （Dm） genetic components.For the model including genotype×environment interaction （GE）,GE can also be partitioned into components of direct additive by environment interaction （AE）,direct dominance by environment interaction （DE）,sex-linked by environment interaction （LE）,maternal additive by environment interaction （AmE ）,and maternal dominance by environment interaction （DmE）.Linear functions of genetic components are listed for parent,F1,and F2.A set of parents,their reciprocal F1’s and F2’s is applicable for efficient analysis.Variance and covariance components can be well mated by MINQUE（O/l） with the jackknife procedure.The t-test conducted by the jackknife procedure is applicable for detecting significance of variation.Adjusted Unbiased Prediction （AUP） method is suggested for predicting genetic effects.

Genomic regions associated with the sex-linked inhibitor of dermal melanin in Silkie chicken

A unique characteristic of the Silkie chicken is its fibromelanosis phenotype.The dermal layer of its skin,its connective tissue and shank dermis are hyperpigmented.This dermal hyperpigmentation phenotype is controlled by the sex-linked inhibitor of dermal melanin gene(ID)and the dominant fibromelanosis allele.This study attempted to confirm the genomic region associated with ID.By genotyping,ID was found to be closely linked to the region between GGA_rs16127903 and GGA_rs14685542(8406919 bp)on chromosome Z,which contains ten functional genes.The expression of these genes was characterized in the embryo and 4 days after hatching and it was concluded that MTAP,encoding methylthioadenosinephosphorylase,would be the most likely candidate gene.Finally,target DNA capture and sequence analysis was performed,but no specific SNP(s)was found in the targeted region of the Silkie genome.Further work is necessary to identify the causal ID mutation located on chromosome Z.

High expression of BCL6 inhibits the differentiation and development of hematopoietic stem cells and affects the growth and development of chickens

Background:B-cell CLL/lymphoma 6(BCL6)is a transcriptional master regulator that represses more than 1200 potential target genes.Our previous study showed that a decline in blood production in runting and stunting syndrome(RSS)affected sex-linked dwarf(SLD)chickens compared to SLD chickens.However,the association between BCL6 gene and hematopoietic function remains unknown in chickens.Methods:In this study,we used RSS affected SLD(RSS-SLD)chickens,SLD chickens and normal chickens as research object and overexpression of BCL6 in hematopoietic stem cells(HSCs),to investigate the effect of the BCL6 on differentiation and development of HSCs.Results:The results showed that comparison of RSS-SLD chickens with SLD chickens,the BCL6 was highly expressed in RSS-SLD chickens bone marrow.The bone marrow of RSS-SLD chickens was exhausted and red bone marrow was largely replaced by yellow bone marrow,bone density was reduced,and the levels of immature erythrocytes in peripheral blood were increased.At the same time,the hematopoietic function of HSCs decreased in RSS-SLD chickens,which was manifested by a decrease in the hematopoietic growth factors(HGFs)EPO,SCF,TPO,and IL-3,as well as hemoglobinα1 and hemoglobinβexpression.Moreover,mitochondrial function in the HSCs of RSS-SLD chickens was damaged,including an increase in ROS production,decrease in ATP concentration,and decrease in mitochondrial membrane potential(ΔΨm).The same results were also observed in SLD chickens compared with normal chickens;however,the symptoms were more serious in RSS-SLD chickens.Additionally,after overexpression of the BCL6 in primary HSCs,the secretion of HGFs(EPO,SCF,TPO and IL-3)was inhibited and the expression of hemoglobinα1 and hemoglobinβwas decreased.However,cell proliferation was accelerated,apoptosis was inhibited,and the HSCs entered a cancerous state.The function of mitochondria was also abnormal,ROS production was decreased,and ATP concentration andΔΨm were increased,which was related to the inhibition of apoptosis of stem cells.Conclusions:Taken together,we conclude that the high expression of BCL6 inhibits the differentiation and development of HSCs by affecting mitochondrial function,resulting in impaired growth and development of chickens.Moreover,the abnormal expression of BCL6 might be a cause of the clinical manifestations of chicken comb,pale skin,stunted growth and development,and the tendency to appear RSS in SLD chickens.

Sex Determination in the Near Threatened Guadalupe Fur Seal: Molecular Markers and Their Potential Applications

The determination of sex by simple observation is often difficult in marine mammals, even in sexually dimorphic species. Moreover, there is often the practical necessity to determine sex in samples that have been collected without handling or observing the subjects. In these cases, a molecular assay for sex determination is required. We adapted an assay that targets the zinc-finger region and is based on a single primer pair, to the Guadalupe fur seal, a near threatened species that has a very limited breeding range. First, we validated the assay with a sample of pups in which we determined the sex by direct observation during handling;second, we compared it to a more recent assay, based on two different primer pairs and, finally, we evaluated the effect of DNA quantity on its reliability. The assay that we tested produced excellent results and was more reliable than the other one based on two primers. Reliable results were also obtained when only remarkably small quantities of DNA were amplified. These results show the potential use of this molecular assay in case of non-invasive sampling, an overly common situation when dealing with species of problematic conservation status.