Regularities and irregularities in the structure of the seminiferous epithelium in the domestic fowl (Gallus domesticus). I. Suggestion of the presence of the seminiferous epithelial cycle

In Silico Identification of lncRNAs Regulating Sperm Motility in the Turkey (Meleagris gallopavo L.)

Long non-coding RNAs (lncRNAs) are transcripts not translated into proteins with a length of more than 200 bp. LncRNAs are considered an important factor in the regulation of countless biological processes, mainly through the regulation of gene expression and interactions with proteins. However, the detailed mechanism of interaction as well as functions of lncRNAs are still unclear and therefore constitute a serious research challenge. In this study, for the first time, potential mechanisms of lncRNA regulation of processes related to sperm motility in turkey were investigated and described. Customized bioinformatics analysis was used to detect and identify lncRNAs, and their correlations with differentially expressed genes and proteins were also investigated. Results revealed the expression of 863 new/unknown lncRNAs in ductus deferens, testes and epididymis of turkeys. Moreover, potential relationships of the lncRNAs with the coding mRNAs and their products were identified in turkey reproductive tissues. The results obtained from the OMICS study may be useful in describing and characterizing the way that lncRNAs regulate genes and proteins as well as signaling pathways related to sperm motility.

Avian Reproduction

There are about 10,400 living avian species belonging to the class Aves, characterized by feathers which no other animal classes possess and are warm-blooded vertebrates with four-chamber heart. They have excellent vision, and their forelimbs are modified into wings for flight or swimming, though not all can fly or swim. They lay hard-shelled eggs which are a secretory product of the reproductive system that vary greatly in colour, shape and size, and the bigger the bird, the bigger the egg. Since domestication, avian species have been basically reared for eggs, meat, pleasure and research. They reproduce sexually with the spermatozoa being homogametic and carry Z-bearing chromosomes, and the blastodisk carries either Z-bearing or W-bearing chromosomes, hence, the female is heterogametic, and thus, determines the sex of the offspring. The paired testes produce spermatozoa, sex hormones and the single ovary (with a few exceptions) produces yolk bearing the blastodisk and sex hormones. Both testis and ovary are the primary sex organs involved in sexual characteristics development in avian. In avian reproduction, there must be mating for fertile egg that must be incubated to produce the young ones. At hatch, hatchling sex is identified and reared to meet the aim of the farmer.

Progress Toward the Culture and Transformation of Chicken Blastodermal Cells

Chicken blastodermal cells can be cultured for short periods of time and retain the ability to contribute to somatic and germline tissues when injected into gamma-irradiated stage X embryos. Such a method has yet to yield a germline transgenic bird, in part due to the low rate of transgene integration into the avian genome. In addition, the short culture period precludes the identification and expansion of those cells that carry an integrated transgene. In this study, two methods were developed that produced blastodermal cells isolated from stage X Barred Plymouth Rock embryos bearing an integrated transgene. Addition of chick embryo extract to the culture medium enabled expansion of single colonies for multiple passages. Southern blot analysis indicated that the transgenes had integrated as a single copy in most of the clones. Cells from passaged, transgenic embryo cells were injected into irradiated stage X White Leghorn embryos, producing hatched chicks that bore the donor cells in their somatic tissues. Transgene sequences were detected in sperm DNA; however, breeding of chimeras did not result in germline transmission of the transgene, indicating that the contribution of the transgenic cells to the germline was either nonexistent or very low.

Differentiation of female primordial germ cells in the male testes of chicken (Gallus gallus domesticus)

In our previous studies, we demonstrated that female primordial germ cells (PGCs) have the ability to differentiate into W chromosome-bearing (W-bearing) spermatozoa in male gonads of germline chimeric chickens. In this study, to investigate the differentiation pattern of female PGCs in male gonads in chickens, three germline chimeric chickens were generated by injecting female PGCs into the male recipient embryos. After these male chimeras reached sexual maturity, the semen samples were analyzed for detecting W-bearing cells by PCR and in situ hybridization analyses. The results indicated that the female PGCs had settled and differentiated in their testes. A histological analysis of the seminiferous tubule in those chimeras demonstrated that the W-bearing spermatogonia, spermatocytes, and round spermatids accounted for 30.8%, 32.7%, and 28.4%, respectively. However, the W-bearing elongating spermatid was markedly lower (7.7%) as compared to the W-bearing round spermatid. The W-bearing spermatozoa were hardly ever observed (0.2%). We concluded that although female PGCs in male gonads are capable of passing through the first and second meiotic division in adapting themselves to a male environment, they are hardly complete spermiogenesis.

Regularities and irregularities in the structure of the seminiferous epithelium in the domestic fowl (Gallus domesticus). II. Co-ordination between germ cell associations

It was investigated in the domestic fowl, whether a mechanism for a synchronous start of the proliferation of the differentiating spermatogonia in a transversely cut seminiferous tubule (called the "co-ordination" between germ cell association) operates effectively in this species. A trapezoid-shaped cellular association demarcated by two perpendiculars from the tubular lumen to the basement membrane was the unit of observation (provisionally called a "column" Each column is composed of a bundle of elongate spermatids and the neighbouring, various types of germ cells). The extent of closeness of the co-ordination was examined in a total of 2,650 columns, based on the continuity of the spermiogenic step-number of the youngest generation of spermatids within adjacent columns. In no case did all columns in a tubular cross section show the same-step spermatids. In most cases (50.2% of 2,650 columns), the same number was kept in only 2 to 6 adjacent columns. The arrangement of different but consecutive numbers (e.g., 1-2-3 or 1-2-1) was observed in a total of 882 columns. The co-ordination mechanism, therefore, is considered to work, albeit incomplete, among a limited number of adjacent columns in this species.