Association of VIPR-1 gene polymorphisms and haplotypes with egg production in laying quails.

The laying quail is a worldwide breed which exhibits high economic value. In our current study, the vasoactive intestinal peptide receptor-1 (VIPR-1) was selected as the candidate gene for identifying traits of egg production. A single nucleotide polymorphism (SNP) detection was performed in 443 individual quails, including 196 quails from the H line, 202 quails from the L line, and 45 wild quails. The SNPs were genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Two mutations (G373T, A313G) were detected in all the tested quail populations. The associated analysis showed that the SNP genotypes of the VIPR-1 gene were significantly linked with the egg weight of G373T and A313G in 398 quails. The quails with the genotype GG always exhibited the largest egg weight for the two mutations in the H and L lines. Linkage disequilibrium (LD) analysis indicated that G373T and A313G loci showed the weakest LD. Seven main diplotypes from the four main reconstructed haplotypes were observed, indicating a significant association of diplotypes with egg weight. Quails with the h1h2 (GGGT) diplotype always exhibited the smallest egg weight and largest egg number at 20 weeks of age. The overall results suggest that the alterations in quails may be linked with potential major loci or genes affecting reproductive traits.

Identification of Z-OTU protein during zebrafish oogenesis and early embryogenesis.

Zebrafish (Danio rerio) Z-OTU, containing OTU and TUDOR domains, was predicted to be a member of OTU-related protease, a family of the deubiquitylating enzymes (DUBs). A previous report from our laboratory clearly describes the expression patterns of z-otu mRNA. Here, we characterized the Z-OTU protein during zebrafish oogenesis and early embryogenesis. After prokaryotic expression, the recombinant protein of the OTU domain and GST was purified and injected into rabbits to obtain the polyclonal antibody-anti-Z-OTU, which was used for immunohistochemistry in zebrafish ovaries and embryos. Interestingly, obvious differences existed between the expression patterns of z-otu mRNA and its protein during oogenesis and early embryogenesis. In stage I oocytes, z-otu mRNA was detected in cytoplasm while its protein existed in the germinal vesicle. In addition, its protein was distributed during entire oogenesis, while mRNA was not detected in oocytes at stage IV or mature oocytes. The z-otu mRNA disappeared after midblastula transition (MBT) and its protein gradually decreased after this stage. We inferred that Z-OTU protein, like other OTU-related protease with DUB activity, was required for germinal vesicle breakdown of oocytes during meiosis, germinal vesicle migration, and embryo cleavage maintenance.

Cloning and expression profiling of the VLDLR gene associated with egg performance in duck (Anas platyrhynchos).

BACKGROUND: The very low density lipoprotein receptor gene (VLDLR), a member of the low density lipoprotein receptor (LDLR) gene family, plays a crucial role in the synthesis of yolk protein precursors in oviparous species. Differential splicing of this gene has been reported in human, rabbit and rat. In chicken, studies showed that the VLDLR protein on the oocyte surface mediates the uptake of yolk protein precursors into growing oocytes. However, information on the VLDLR gene in duck is still scarce. METHODS: Full-length duck VLDLR cDNA was obtained by comparative cloning and rapid amplification of cDNA ends (RACE). Tissue expression patterns were analysed by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR). Association between the different genotypes and egg performance traits was investigated with the general linear model (GLM) procedure of the SAS® software package. RESULTS: In duck, two VLDLR transcripts were identified, one transcript (variant-a) containing an O-linked sugar domain and the other (variant-b) not containing this sugar domain. These transcripts share ~70 to 90% identity with their counterparts in other species. A phylogenetic tree based on amino acid sequences showed that duck VLDLR proteins were closely related with those of chicken and zebra finch. The two duck VLDLR transcripts are differentially expressed i.e. VLDLR-a is mainly expressed in muscle tissue and VLDLR-b in reproductive organs. We have localized the duck VLDLR gene on chromosome Z. An association analysis using two completely linked SNP sites (T/C at position 2025 bp of the ORF and G/A in intron 13) and records from two generations demonstrated that the duck VLDLR gene was significantly associated with egg production (P < 0.01), age of first egg (P < 0.01) and body weight of first egg (P < 0.05). CONCLUSIONS: Duck and chicken VLDLR genes probably perform similar function in the development of growing oocytes and deposition of yolk lipoprotein. Therefore, VLDLR could be a candidate gene for duck egg performance and be used as a genetic marker to improve egg performance in ducks.

[Soil organic carbon density of Eucalyptus plantations in Guangdong province of China and related affecting factors].

Soil samples were collected from the Eucalyptus plantations in the north, east, and west Guangdong and Pearl River Delta region to study their organic carbon content and density, and the main factors affecting the organic carbon density. In the plantations, the soil organic carbon content and density in A and B horizons were significantly different, with the values of (23.94 +/- 2.97) g x kg(-1) and (9.68 +/- 1.05) g x kg(-1), and (27.64 +/- 7.72) t x hm(-2) and (108.36 +/- 9.37) t x hm(-2), respectively. In 0-50 cm soil layer, the organic carbon density was 66.72 +/- 6.53 t x hm(-2), being slightly higher than that in Masson pine and Chinese fir plantations in Guangdong. In both A and B horizons of Eucalyptus plantations, soil organic carbon density was significantly positively correlated with altitude, soil total porosity, capillary porosity, capillary moisture capacity, and total nitrogen content. Soil capillary porosity, capillary moisture capacity, and pH value were the main factors affecting the soil organic carbon density.

[Expression of cyclin-dependent kinase 2-associated protein 1 in chicken embryos of different sexes].

To investigate the expression and functions of cyclin-dependent kinase 2-associated protein 1 (cdk2ap1) screened by suppression subtractive hybridization in chicken embryo development, a pair of primers was designed to amplify the cdk2ap1 fragment by RT-PCR and subsequently the fragment obtained was cloned into the plasmid pGEM-T. Sense and antisense probes labeled with digoxigenin were generated using SP6 and T7 RNA polymerases, respectively, and used to examine cdk2ap1 expression in chicken embryos of both sexes by whole-mount in situ hybridization. In both sexes, cdk2ap1 was expressed in the head mesenchyme, rhombencephalon, optic vesicles, spinal neural tube, and forelimb of 4.0-day-old embryos and the expression in males was significantly higher than that in females. In addition, in the genital ridge and hindlimb of the 4.0-day-old chicken embryo, cdk2ap1 was obviously expressed in the males but not in females. It is supposed that cdk2ap1 may play a role in the sexual differentiation and development of gonad of chicken embryo.