Nucleolar organizer regions, satellite associations and nucleoli of goat cells (<i>Capra hircus</i>)

Abstract

Abstract. 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 AgNO,sub>3 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.

Structure of the nucleoli in domestic cattle spermatocytes

“…A comparison between the results obtained for the number of meiotic nucleoli and the number of active NORs in domestic cattle [19] revealed differences between the number of NORs and nucleoli. Such differences have also been observed in geese [10], goats [11], hens and quails [12] and horses [13]. These differences are due to the participation of several NORs in the formation of one nucleolus [3].…”

“…On the other hand, domestic goose cells were found to contain between one and four differentlysized nucleoli, the cells predominantly containing one or two nucleoli [10]. Goat spermatocytes have two nucleoli of the same size and different staining intensity [11]. Only one meiotic nucleolus was observed in the domestic horse.…”

“…Throughout the prophase, nucleoli are not degraded. As opposed to mitotic NORs, they are large structures [10][11][12][13]. The nucleolus is considered to be one of the strongest promoters of cellular growth, directly associated with the cell cycle and anti-stress reactions.…”

Age-Dependent Change in the Morphology of Nucleoli and Methylation of Genes of the Nucleolar Organizer Region in Japanese Quail (<I>Coturnix japonica</I>) Model (Temminck and Schlegel, 1849) (Galliformes: Aves)

“…A standard technique for isolating meiotic chromosomes (POLLOCK & FECHHEIMER 1978) in combination with a modified procedure for identifying nucleolar organizing regions (HOWELL & BLACK 1980) could be used successfully to isolate, observe and identify nucleoli in spermatocytes during the first meiotic prophase (ANDRA- SZEK & SMALEC 2007;ANDRASZEK et al 2009;.…”

“…Nucleoli lying close to each other may become fused together (RAŠKA et al 2006), or satellite chromosomes may become associated with active NOR (ANDRASZEK et al 2009). Moreover, genes located in different NOR-chromosomes are involved in Age-Dependent Change of Genes of NOR in Japanese Quail the formation of one nucleolus.…”