Histochemical Detection of Glycoconjugates in the Inner Perivitelline Layer of Japanese Quail (Coturnix japonica)

Transcriptome and Proteome Analysis Revealed Key Pathways Regulating Final Stage of Oocyte Maturation of the Turkey (Meleagris gallopavo)

In birds, the zona pellucida (ZP) matrix that surrounds the ovulated oocyte—called the inner perivitelline layer—is involved in sperm–zona interaction and successful fertilization. To identify the important genes and proteins connected with the final step of egg development, next-generation sequencing and two-dimensional electrophoresis, combined with mass spectrometry, were used for the analysis of mature oocytes at the F1 developmental stage. A total of 8161 genes and 228 proteins were annotated. Six subfamilies of genes, with codes ZP, ZP1–4, ZPD, and ZPAX, were identified, with the dominant expression of ZPD. The main expression site for ZP1 was the liver; however, granulosa cells may also participate in local ZP1 secretion. A ubiquitination system was identified in mature oocytes, where ZP1 was found to be the main ubiquitinated protein. Analysis of transcripts classified in estrogen receptor (ESR) signaling indicated the presence of ESR1 and ESR2, as well as a set of estrogen-dependent genes involved in both genomic and nongenomic mechanisms for the regulation of gene expression by estrogen. Oxidative phosphorylation was found to be a possible source of adenosine triphosphate, and the nuclear factor erythroid 2-related factor 2 signaling pathway could be involved in the response against oxidative stress. Oocyte–granulosa cell communication by tight, adherens, and gap junctions seems to be essential for the final step of oocyte maturation.

Characterization of structure and protein of vitelline membranes of precocial (ring-necked pheasant, gray partridge) and superaltricial (cockatiel parrot, domestic pigeon) birds

Of all the known oviparous taxa, female birds lay the most diverse types of eggs that differ in terms of shape, shell pigmentation, and shell structure. The pigmentation of the shell, the weight of the egg, and the composition of the yolk correlate with environmental conditions and the needs of the developing embryos. In this study, we analyzed the structure and protein composition of the vitelline membrane (VM) of ring-necked pheasant, gray partridge, cockatiel parrot, and domestic pigeon eggs. We found that the VM structure is characteristic of each species and varies depending on whether the species is precocial (ring-necked pheasant and gray partridge) or superaltrical (cockatiel parrot and domestic pigeon). We hypothesize that a multilayer structure of VM is necessary to counteract the aging process of the egg. The multilayer structure of VM is only found in species with a large number of eggs in one clutch and is characterized by a long incubation period. An interesting discovery of this study is the three-layered VM of pheasant and partridge eggs. This shows that the formation of individual layers of VM in specific sections of the hen's reproductive system is not confirmed in other species. The number of protein fractions varied between 19 and 23, with a molecular weight ranging from 15 to 250 kDa, depending on the species. The number of proteins identified in the VM of the study birds' eggs is as follows: chicken-14, ring-necked pheasant-7, gray partridge-10, cockatiel parrot-6, and domestic pigeon-23. The highest number of species-specific proteins (21) was detected in the VM of domestic pigeon. This study is the first to present the structure and protein composition in the VM of ring-necked pheasant, gray partridge, cockatiel parrot, and domestic pigeon eggs. In addition, we analyzed the relationship between the hatching specification of birds and the structure of the VM.

Neurotrophins and Trk receptors in the developing and adult ovary of Coturnix coturnix japonica

NGF, BDNF, NT-3 and their specific receptors TrkA, TrkB and TrkC are known to be involved in the development and maintenance of vertebrates' nervous system. However, these molecules play a role also in non-neuronal tissue, such as in the reproductive system. In this study we investigated the presence and localization of neurotrophins and Trk receptors to unravel their potential role in the developing and adult ovary of Japanese quail, a model species well suited for reproduction studies. Western blotting analysis on ovaries of three month old quails in the period of egg laying showed the presence of pro and mature forms of neurotrophins and splice variants of Trk receptors. Immunohistochemical investigation reported that in embryonic ovaries from the 9th day of incubation to the hatching NGF and NT-3 were observed in the cortical and medullar areas respectively, whereas Trk receptors were observed in both areas. In adult ovary, all NTs were detected in glandular stromal cells, NGF and NT-3 also in the nervous component. Regarding follicle components, NGF and BDNF were observed in oocytes and follicular cells. All TrK receptors were present in nervous components and only TrkA in glandular stromal cells. In follicles, TrkA was present in oocyte cytoplasm and TrkB in theca cells. The results suggest an involvement of the neurotrophin system in the quail ovary physiology, promoting the oocyte development and follicular organization in the embryo, as well as oocyte and follicular maturation in adults.

Auxiliary effects of camphor on reproductive function of Japanese quail

In recent decades, reproductive problems were raised alongside the continuous genetic selection for performance purposes in poultry. As such, a negative correlation was observed between reproductive and production performance, which may possibly imply that the high growth rate in poultry causes physiological disorders such as decreased libido and frequency of mating. A study was conducted to establish the efficacy of feeding graded levels of camphor on reproductive function of Japanese quail as a bird model. Two-hundred-and-eighty one-day-old quail chicks were randomly assigned to individual cages in 7 treatments (zero [control], 250, 500, 750, 1,000, 5,000, or 10,000 ppm of camphor). The results demonstrated that testosterone concentration displayed an uncertain attitude, as the lower dosages of camphor used (250, 500, and 750 ppm) had the highest values. Thyroxine (T₄) linearly increased with increasing camphor levels in male birds (P < 0.05). Triiodothyronine (T₃) also was increased in the groups receiving a camphor-containing diet in comparison with the control (P < 0.05). The male birds' libido behavior was linearly increased with the increase of camphor concentration (P < 0.05). Dietary camphor in 500 and 10,000 ppm caused the highest percentage of fertility (P < 0.0001) and hatchability (P = 0.0117), respectively. As well, the groups with 5,000 and 10,000 ppm of camphor accounted for the highest percentage of hatched-fertile eggs (P = 0.0055). The highest rate of sperm penetration in the yolk inner perivitelline layer (IPVL) was demonstrated by the group allotted with 10,000 ppm camphor (P < 0.05). This group also had the highest hole persistency in IPVL. Conclusively, the result indicated that camphor can be added in poultry diet for the improvement of reproductive functions.

Differential expression and localization of glycosidic residues in in vitro- and in vivo-matured cumulus-oocyte complexes in equine and porcine species

Glycoprotein oligosaccharides play major roles during reproduction, yet their function in gamete interactions is not fully elucidated. Identification and comparison of the glycan pattern in cumulus-oocyte complexes (COCs) from species with different efficiencies of in vitro spermatozoa penetration through the zona pellucida (ZP) could help clarify how oligosaccharides affect gamete interactions. We compared the expression and localization of 12 glycosidic residues in equine and porcine in vitro-matured (IVM) and preovulatory COCs by means of lectin histochemistry. The COCs glycan pattern differed between animals and COC source (IVM versus preovulatory). Among the 12 carbohydrate residues investigated, the IVM COCs from these two species shared: (a) sialo- and βN-acetylgalactosamine (GalNAc)-terminating glycans in the ZP; (b) sialylated and fucosylated glycans in cumulus cells; and (c) GalNAc and N-acetylglucosamine (GlcNAc) glycans in the ooplasm. Differences in the preovulatory COCs of the two species included: (a) sialoglycans and GlcNAc terminating glycans in the equine ZP versus terminal GalNAc and internal GlcNAc in the porcine ZP; (b) terminal galactosides in equine cumulus cells versus terminal GlcNAc and fucose in porcine cohorts; and (c) fucose in the mare ooplasm versus lactosamine and internal GlcNAc in porcine oocyte cytoplasm. Furthermore, equine and porcine cumulus cells and oocytes contributed differently to the synthesis of ZP glycoproteins. These results could be attributed to the different in vitro fertilization efficiencies between these two divergent, large-animal models.

Expression of intermediate filaments in the Balbiani body and ovarian follicular wall of the Japanese quail (Coturnix japonica)

In the present study, we examined the distribution of 6 groups of intermediate filaments (IFs; cytokeratins, CKs, vimentin, synemin, desmin, glial fibrillary acidic protein and lamins) in oocytes and follicular walls of the Japanese quail (Coturnix japonica) during their development using immunohistochemical and ultrastructural techniques. A distinctly vimentin- and synemin-positive Balbiani body, which is a transient accumulation of organelles (mitochondria, Golgi complex and endoplasmic reticulum) that occurs in the oocytes of all vertebrates including birds, could be detected in the oocytes of primordial and early pre-vitellogenic follicles. In larger pre-vitellogenic follicles, the Balbiani body has dispersed and the positivity of the granulosa cells appeared to concentrate in the basal portion of their cytoplasm. Our ultrastructural data demonstrated that the matrix of the Bal-biani body consists of fine IFs, which may play a role in the formation and dispersion of the Balbiani body. Of the CKs studied (panCK, CK5, CK7, CK8, CK14, CK15, CK18 and CK19), only CK5 showed a slight positive staining in both the theca externa and the Balbiani bodies of pre-vitellogenic oocytes. In conclusion, our data, which describe the changes in avian IF protein expression during folliculogenesis, suggest that the functions of the IFs (vimentin and synemin) of oocytes and follicular walls are not primarily mechanical but may be involved in the transient tethering of mitochondria in the area of the Balbiani body and in the gain of endocrine competence during the differentiation of granulosa cells.