Urszula Stępińska

Learn More
Melatonin plays a pleiotropic role in the immune system of mammals and birds. Endogenous and exogenous melatonin modulates lymphocyte proliferation via specific MT(1), MT(2) and Mel(1c) membrane receptors, although the mechanisms behind this process are poorly understood. The diurnal changes in the expression and function of melatonin membrane receptors(More)
The presence of melatonin and the enzymes (transcripts and activities) involved in its synthesis, i.e. arylalkylamine N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), was investigated in the eggs and early embryos of Japanese quail at Hamburger-Hamilton stages 1-10. Melatonin was present in the egg yolk (approximately 70 pg/g) and(More)
In this paper, we summarise studies which have been carried out on the metabolism of nucleic acids (maternal RNA, DNA, nucleolytic enzymes) in avian oocytes and embryos (Japanese quail, Coturnix coturnix japonica ) within the last 10 years in the Institute of Genetics and Animal Breeding of the Polish Academy of Sciences. The accumulation of maternal RNA in(More)
The presence of melatonin receptor transcripts (mel-1a, mel-1b and mel-1c) was investigated in primordial germ cells (PGCs), immature and mature oocytes, and sperm of Japanese quail by reverse transcription--polymerase chain reaction (RT-PCR). The mel-1a transcript was detected in as few as in a thousand PGCs. Significant differences in the expression of(More)
1. An in vitro system for ovulation and maturation of Japanese quail oocytes is described. 2. Ovarian follicles removed from the ovary at 2, 4 or 6 h before the estimated time of ovulation may ovulate under in vitro conditions. 3. The presence of progesterone in the medium had a stimulatory effect on the process of maturation, as has been shown for Xenopus(More)
During polyspermic fertilisation in birds numerous spermatozoa enter the eggs, in contrast to the situation in mammals where fertilisation is monospermic. However, in birds only one of the spermatozoa which have entered an egg participates in zygote nucleus formation, while the supernumerary spermatozoa degenerate at early embryogenesis. Our previous work(More)
The presence of poly(A)-degrading activity was studied in vitro in the quail and mouse oocytes and early embryos using 3H-poly(A) as a substrate. The activity was measured by adsorption of the undegraded substrate to DE-81 filter paper discs, by chromatographic separation on Sephadex G-50 column and by agarose gel electrophoresis followed by transfer onto a(More)
The development of 11 1/2-13 1/2-day embryonic mouse ovaries subjected to the influence of adult and embryonic testes was investigated. The environment of adult testis caused severe restriction of ovarian growth, but did not produce any effects which might be considered as masculinization. The presence of embryonic testis was distinctly unfavourable to the(More)
The development of quail embryos obtained after in vitro fertilization of oocytes ovulated in vitro was investigated. About 40% of the specimens, after 18-20 hr of incubation, had undergone cleavage to reach stages IV-VI when viewed under a stereo microscope. However, only 36% of these embryos contained normal, DAPI-stained nuclei when observed under a(More)
The expression of nine serotonin (5-HT) receptor transcripts was studied using reverse transcription polymerase chain reaction (RT-PCR) in germ cells, cleavage and gastrulation stages of Japanese quail, and qPCR for 5-HT3 and 5-HT4 receptors in oocytes and embryos. We show the presence/absence of nine serotonin transcripts known in birds for receptors(More)