Structure of the nucleoli in domestic cattle spermatocytes

The work was aimed at determining the number and morphology of nucleoli in the prophase of the first meiotic division in domestic cattle males. The use of AgNO3 staining, commonly applied in cytogenetics for the identification of nucleolar organiser regions, made it possible to identify nucleoli in first-order spermatocytes. One nucleolus was identified in each analysed cell. Considerable morphological differentiation of the nucleoli during the prophase of the first meiotic division, particularly in leptotene, unobserved in other farm animal species, was noticed. Dark-hued grain-like structures were found within the disintegrating nucleoli, corresponding approximately or exactly to the number of the nucleolar organiser regions in the domestic cattle karyotype. Dark areas were identified in the selected prometaphase chromosomes. Their number corresponded with the number of active NORs defined in the domestic cattle karyotype

Structure of the nucleoli in domestic cattle spermatocytes

The use of AgNO3 staining, commonly applied in cytogenetics to identify nucleolar organizer regions, has made it possible to identify nucleoli in primary spermatocytes. One nucleolus was identified in each analyzed cell. Considerable morphological differentiation of the nucleoli during the prophase of the first meiotic division, particularly in leptotene, unobserved in other farm animal species, was noticed. Dark-hued grain-like structures were found within the disintegrating nucleoli, corresponding approximately or exactly to the number of the nucleolar organizer regions in the domestic cattle karyotype. Dark areas were identified in the selected prometaphase chromosomes. Their number corresponded with the number of active NORs defined in the domestic cattle karyotype

Number and size of nucleoli in the spermatocytes of European domestic goose (Anser anser)

The basic nucleolus function is to form subunits of ribosomes and the transcription of genes encoding rRNA. The source of information on the activity of genes encoding rRNA may be an analysis of the number and size of nucleoli in the prophase of the first meiotic division or an analysis of nucleolar organizer regions. Meiotic chromosomes isolated from the nuclei of sixteen-week males of European domestic goose were evaluated in respect to the number and size of nucleoli in the cell. A varied number (from 1 to 4) and different size of nucleoli in the cells of examined individuals were found. Among the total number of 329 nucleoli 257 were classified as large and 72 as small ones

Modifications of lampbrush chromosome structure of the European domestic goose Anser anser

Lampbrush chromosomes (LBCs) represent a new model in avian cytogenetics and are increasingly more often used in poultry chromosome analyses. Additionally, lampbrush chromosomes are considered as model structures in the study of transcription regulation. Changes in transcription activity are reflected as modifications of LBC morphological structure and associated with physiological processes in the organism. The aim of the present study was to compare transcriptional activity of the first five lampbrush macrochromosomes and ZW sex lampbrush bivalents sampled from the oocytes of geese prior to and after the reproductive period. The respective bivalents sampled before and after reproduction have similar sizes but differ in morphological structure. Side loops of lampbrush chromosomes are sites of transcription activity. The activity varies according to the loop size. As the loops become more prominent, the activity grows and vice versa. Lampbrush chromosomes sampled after reproduction have smaller side loops. On the other hand, inactive chromomeres become prominent in the chromosomes. Marker loops are the last structures to be degraded after the end of reproduction. Consequently, they are used for identifying particular bivalents at different stages of cellular transcriptional activity

Spermatogenesis process as exemplified by meiosis in European domestic goose (Anser anser)

A large diploid number typical of birds and the presence of microchromosomes restrict a cytogenetic analysis in poultry. Standard methods of chromosome analysis do not allow an identification of chromosomes. As a result, alternative methods based on meiotic chromosome analysis are applied. The studies carried out made it possible to obtain meiotic chromosomes of ganders. Chromosomes at different stages of meiosis were arranged according to their structure during spermatogenesis. The results presented are the only study on bird meiosis, and they can be as well treated as a material applicable in goose cytogenetics and reproduction biology but also as a teaching aid

DNA methylation analysis of the gene CDKN2B in Gallus gallus (chicken)

Methylation is an epigenetic modification of DNA affecting gene expression without changing the structure of nucleotides. It plays a crucial role in the embryonic and post-embryonic development of living organisms. Methylation level is tissue and species-specific and changes with age. The study was aimed at identifying the methylation of the CDKN2B gene situated at locus bar in Polbar chickens on the 6th and 18th day of embryonic development using the MSP (methylation-specific PCR) method. Methylation was not detected in the promoter region of gene CDKN2B on the 6th and 18th day of embryonic development. As one of the five genes responsible for melanine activity in melanocytes and highly active, it can contribute to the production of this pigment. The present research broadens the current knowledge of the chicken epigenome and the mechanism of autosexing in birds

Nucleolar organizer regions, satellite associations and nucleoli of goat cells (Capra hircus)

The Polish White Improved goat karyotype consists of 29 pairs of acrocentric autosomes, a large acrocentric X chromosome and a metacentric Y chromosome which is the smallest in the karyotype. Staining of chromosomes with AgNO3 solution has revealed active nucleolar organizer regions (NOR) in terminal parts of q arms of pair 2, 3, 4, 5, and 28 chromosomes. Out of the total of 100 analysed cells 736 active NORs have been found, on average 7.4±0.2 per cell. Active NORs were most frequently observed in pair 2, and 3 chromosomes, most rarely on pair 5 chromosomes. In all the analysed cells 141, satellite associations (SA) were observed, on average 1.4±0.2 per cell. SAs most often occurred in cells with seven active NORs, and least often in cells with three or four nucleolar organizer regions. Most frequently in SAs the presence of pair 2, 3 and 28 chromosomes was observed. On meiotic chromosomes staining with AgNO3 solution revealed two nucleoli stained with different intensity. Both nucleoli in the cell were of similar size

Description of G bands on the chromosomes of the European domestic goose (Anser anser)

The most complete information on a karyotype is gained by means of direct observation of chromosomes obtained from dividing cells. Precise chromosome studies are based on differentiating banding of chromatids. G bands replicate in late phase S of the cell cycle, they are rich in A-T pairs and they usually occur in the genome non-coding sequences. GTG banding is a technique applied in constructing standardised karyotype patterns. A chicken karyotype standard exists only for Gallus domesticus. Limited research on the karyotypes of other poultry species results from specific characteristics of the avian karyotype (number and size of chromosomes) which make it more difficult to carry out analyses, especially on the cytogenetic level. The least studied poultry genome is that of geese. By using GTG banding on the chromosomes of Anser anser geese, the pattern of G bands on the first eight autosomes and chromosomes W and Z was established. Altogether forty-eight positive bands were determined on the analysed chromosomes