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J Motlík

Publications and source records attributed to J Motlík.

At least 37 records · Page 2Linked to original sources
PubMed1989

Activity of maturation promoting factor in pig oocytes after microinjection and serial transfer of maturing cytoplasm.

Microinjection of 120 pl homologous or heterologous (mouse) maturing cytoplasm into immature pig oocytes resulted in germinal vesicle breakdown (GVBD) and chromosome condensation (CC) after 8 h of culture. In contrast, nearly all control oocytes remained at the germinal vesicle stage. Immature cytoplasm did not induce nuclear maturation of recipient oocytes when injected. The cytoplasm of the oocytes injected with maturing cytoplasm preserved the capacity to cause GVBD in the second recipients. These results suggest that the level of injected maturation promoting factor (MPF) must rise before GVBD can occur. When the pig oocytes injected with 120 pl of mouse maturing cytoplasm were cultured in cycloheximide for 8 h, the presence of GVBD was dramatically reduced. Thus, in pig oocytes the increase in active MPF up to the effective concentration requires protein synthesis.

Animals↗
PubMed1989

RNA and protein synthesis requirements for the resumption of meiosis in rabbit oocytes: the role of cumulus cells.

In vitro maturation of rabbit cumulus-enclosed oocytes was fully inhibited in alpha-amanitin- (100 micrograms/ml) and cycloheximide- (5 micrograms/ml) supplemented media. The inhibition was reversible and substantially reduced by delaying the addition of alpha-amanitin (2h) or cycloheximide (3 h). In contrast, both drugs did not inhibit germinal vesicle breakdown in denuded oocytes. Co-culture of granulosa cells (1 x 10(6)/ml) with denuded oocytes did not substitute for an intact cumulus. The data presented here suggest that the resumption of meiosis in rabbit cumulus-enclosed oocytes is dependent upon early transcriptional and translational events which probably occur within the cumulus cells.

Amanitins↗
PubMed1989

In vitro techniques of bovine oocyte maturation, fertilization and embryo culture resulting in the birth of a calf.

Oocyte cumulus complexes were aspirated from 3 to 5 mm follicles of cows prestimulated with 2.000 IU PMSG 24 h before slaughter. Oocytes matured in culture were fertilized in vitro by heparinized freshly ejaculated or epididymal spermatozoa. The cultivation procedure for fertilized eggs was the same as that used for cultivation of oocytes. From 163 matured oocytes, 109 cleaved to the 2-cell stage 24 h after fertilization and after 6 days of cultivation, 18 developed to the late morula and 18 to the blastocyst stages. Eleven blastocyts and 1 late morula were transferred surgically to the uteri of 7 recipient heifers. Two heifers became pregnant: one delivered a bull-calf at term, while the other pregnancy resulted in abortion at the 3rd month. The examination of some embryos by transmission electron microscopy showed an almost normal morphology for most cells. The degenerated cells contained mostly electron-dense residual bodies of unknown origin.

Animals↗
PubMed1988

Does autocatalytic amplification of maturation-promoting factor (MPF) exist in mammalian oocytes?

The method of polyethylene-glycol-induced fusion of mammalian oocytes was applied to study maturation-promoting factor (MPF) activity. After homologous fusions of one maturing--late diakinesis (LD), metaphase I (MI)--pig or mouse oocyte to one, two, or three immature-germinal vesicle (GV)--oocytes, giant cells were cultured in control or cycloheximide supplemented medium for 3 hours. The occurrence of germinal vesicle breakdown (GVBD) and premature chromosome condensation (PCC) served as a control of MPF activity. In giant cells composed of one maturing and one, two or three immature oocytes, GVBD and PCC were observed in all cases after cultivation in the control medium. In the presence of cycloheximide, the completion of GVBD and PCC remained high when one maturing and one immature oocyte were fused (83.7% and 95.7% of GVBD in pig and mouse, respectively). However, in giant cells composed of one maturing and up to three immature oocytes, all GVs were broken down only occasionally (4.8% and 11.7% in pig and mouse, respectively). These results suggest that in pig and mouse oocytes MPF does not amplify autocatalytically, but requires active protein synthesis for its production.

Animals↗
PubMed1986

Activity of maturation promoting factor in mammalian oocytes after its dilution by single and multiple fusions.

Mouse and porcine fully grown oocytes at metaphase I(MI) were fused to one or more fully grown oocytes of the same species that contained an intact germinal vesicle (GV). In fused cells containing one GV, premature chromosome condensation (PCC) was observed. In fused cells containing more than one GV, germinal vesicle breakdown (GVBD) and PCC were delayed. Fusion of an MI fully grown oocyte with a growing oocyte resulted in rapid PCC, whereas, fusion of an MI fully grown oocyte with more than one growing oocyte resulted in neither PCC nor GVBD. Moreover, MI chromosomes formed a clump of chromatin. Results of these experiments suggest that the delay in GVBD in fusions of MI oocytes with multiple GV-intact oocytes was due to dilution of maturation promoting factor (MPF) by the cytoplasm of the GV-intact oocytes and that the cytoplasm of growing oocytes can inhibit MPF present in MI oocytes.

Animals↗
PubMed1986

Effect of cycloheximide on nuclear maturation of pig and mouse oocytes.

Culture of mouse oocytes in medium with 1 or 100 micrograms cycloheximide/ml did not prevent germinal vesicle breakdown (GVBD). In contrast, GVBD in pig oocytes was absolutely blocked at concentrations of 1, 5, 10, 50 and 100 micrograms cycloheximide/ml, respectively. The inhibition of GVBD was not influenced by the presence or absence of cumulus cells and it was fully reversible. When cycloheximide treatment (5 micrograms/ml) was given after preincubation for 6, 12 and 16 h, GVBD occurred in 15, 46 and 75% of oocytes, respectively. It is concluded that proteins important for GVBD of pig oocytes were present in sufficient amounts at about 12 h of culture. The fusion of pig oocytes in metaphase I to oocytes with an intact germinal vesicle revealed that cycloheximide did not inhibit GVBD induced by maturing ooplasm. Therefore, induction of prematurely condensed chromosomes by the maturing ooplasm did not require protein synthesis. However, continuous protein synthesis was necessary to maintain metaphase I and prematurely condensed chromosomes in a typical configuration.

Animals↗
PubMed1985

Inhibition of nuclear maturation in fully grown porcine and mouse oocytes after their fusion with growing porcine oocytes.

Porcine ovarian oocytes, isolated from follicles of 5 mm in diameter (large oocytes), were fused either together or with oocytes isolated from follicles of 0.5 mm in diameter (small oocytes). In giant cells composed of two large oocytes (control) germinal vesicle breakdown (GVBD) occurred and two metaphase I chromosome sets (M I) were observed 24 to 30 h after fusion. By contrast, in giant cells composed of one large and one small porcine oocyte, both germinal vesicles (GVs) remained well conserved after 24-30 h of culture. An identical situation was observed after fusion and cultivation of small porcine and large mouse oocytes isolated from preovulatory follicles. The results demonstrate the presence of inhibiting activity in the ooplasm of small porcine oocytes that prevents nuclear maturation of large porcine and mouse oocytes fused to them. This maturation inhibiting activity can be overcome by preincubating large porcine oocytes for more than 14 h before fusion with small oocytes. During preincubation the ooplasm produces sufficient amount of maturation promoting factor (MPF) to overcome the inhibiting activity present in small porcine oocytes thus inducing GVBD and chromatin condensation both in small and large oocytes.

Animals↗
PubMed1984

RNA synthesis in pig follicular oocytes. Autoradiographic and cytochemical study.

RNA synthesis in pig oocytes was studied using autoradiography and silver staining of the nucleolus organizing region. Both methods confirmed that oocytes from the smallest follicles (0.5-0.7 mm in diam.) very intensely synthesize nuclear and nucleolar RNA. The nucleolar area of oocytes originating from follicles of 1.6-2.2 mm in diam. was labelled mainly on its periphery. After short pulse labelling (15 min) of oocytes from follicles of 5-6 mm in diam. only the nucleoplasm was labelled. The nucleolus had no significant labelling. The possibility that labelling of the compact nucleolus after a longer pulse represents migration of the newly synthesized nuclear RNA into the compact nucleolus, is discussed. The quantity of silver-positive material in dictyate oocytes significantly decreased as pig follicles enlarged in diam. from 2 mm to 5-6 mm.

Animals↗
PubMed1983

Blood types of twin cattle after embryo transfer to inseminated recipients.

The blood types, together with erythrocyte and plasma protein types were determined in 10 pairs of twins born after embryo transfer to the contralateral uterine horns of previously inseminated recipients. These estimations were carried out at the age of nine weeks. According to the haemolytic test, most of these pairs of twins had identical blood types, ie, no erythrocyte mosaic could be demonstrated and the blood type corresponded to that of the recipient's calf. In the cases where mosaicism could be demonstrated, the recipient calf's blood type predominated. The reason for this bias remains unclear although the suggestion that the recipient's calf had developed further and was thus able to influence the haematopoietic tissues of its co-twin is worth considering.

Animals↗
PubMed1982

[Transfer of cattle embryos in the induction of twinning].

The superovulation of donors, heifers and cows, was induced by means of gonadotropin PMSG (Antex Leo) in combination with the synthetic prostaglandin analogue--PGF2 alpha (Estrumate, ICI) applied 48 hours later. The response of donors to this treatment was variable. The average number of ovulating follicles from one heifer was fourteen, and the number of embryos to be used was four. In cows the average number of ovulating follicles amounted to six, and on the average three embryos from one donor could be used. Seventy-four embryos were transferred to thirty-seven recipients, into each horn of uterus one embryo. Twenty-six (70%) cows were pregnant, out of this number seventeen (65%) recipients gave birth to twins. In some cases the isolated embryos were kept in the oviduct of female rabbit for 72 hours. It was proved that this deposition did not exert any negative influence on further development of embryos.

Animals↗
PubMed1981

Fertilization of rabbit oocytes co-cultured with granulosa cells.

Rabbit ovarian oocytes co-cultured with granulosa cells were transferred for fertilization to the oviducts of recipient does. Oocytes with cumulus cells and membrana granulosa cells were isolated before or 3 h after hCG injection. Granulosa cells did not prevent the resumption of meiosis but the time sequence of nuclear maturation was retarded by about 3 h. When oocytes were isolated from FSH-stimulated ovaries and cultured with only their cumulus cells or with cumulus and granulosa cells of the same origin, non-decondensed sperm heads were detected in about 30% oocytes after fertilization. Culture of FSH-stimulated oocytes with granulosa cells isolated 3 h after hCG injection substantially enhanced the development of male pronuclei to 88.2% and regular cleavage to 85.2% 10 h and 20 h after transfer, respectively. Further improvement was observed if the oocytes and their co-cultured granulosa cells had been exposed to hCG for 3 h.

Animals↗
PubMed1980

Distribution of proteins labelled during meiotic maturation in rabbit and pig eggs at fertilization.

The fate of proteins formed during meiotic maturation was examined after fertilization. Rabbit ovarian oocytes were labelled in vitro with [3H]lysine and fertilized after transfer to recipients. A significant accumulatin of the label was detected autoradiographically only in fully grown male and female pronuclei. Pig oocytes at the germinal vesicle and metaphase I stages were labelled with [3H]lysine, [3H]methionine or [3H]tryptophan and fertilized. Pronuclei were labelled by all 3 precursors. During cleavage, eggs labelled with [3H]lysine lost the nuclear label by the 4-cell stage. However the [3H]methionine label was present in the cytoplasm and marked in the nuclei at the 4-cell stage, while the [3H]tryptophan label was still clear in 8-cell embryos.

Animals↗
PubMed1978

Breakdown of the germinal vesicle in bovine oocytes cultivated in vitro.

Breakdown of the germinal vesicle (GV) was studied in bovine follicular oocytes cultivated in vitro. The intact GV of control oocytes did not correspond to the findings in porcine oocytes (GV I). Instead it was characterized by a nuclear membrane and a few chromocenters in finely granular nucleoplasm (GV II). After two and three hours of cultivation, GV III predominated (50% and 64% respectively). Faintly-staining chromatin and after a longer interval in the form of filaments also appeared round the chromocenters. After four hours, 35.8% of the oocytes were still at stage GV III but the GV of 46.6% of the oocytes already contained filamentous bivalents (GV IV). After five hours, GV IV (59.7%) was typical, with a less distinct nuclear membrane and condensing bivalents. GV breakdown was completed in 30.4% of the oocytes after five hours of cultivation and in 92.5% after six hours.

Animals↗