Biomedical subjects

M Waksmundzka

Publications and source records attributed to M Waksmundzka.

6 recordsLinked to original sources

PubMed2001

Electric field-mediated BrUTP uptake by mouse oocytes, eggs, and embryos.

Electropermeabilization was used to introduce 5-bromouridine 5'-triphosphate (BrUTP) into mouse oocytes, zygotes, 2-cell embryos, and parthenogenetic eggs containing nuclei transferred from 3T3 cells. BrUTP incorporated into nascent RNA was detected by indirect immunofluorescence. Two electric pulses of 100 micros duration and of 20 V strength applied at 10 mM concentration of BrUTP loaded most efficiently all cell types tested. Zygotes loaded with BrUTP developed for the next 20 hr in vitro and cleaved to 2-cell stage. The parameters of electric field which promoted BrUTP uptake were also efficient in inducing fusion of blastomeres of 2-cell embryos.

3T3 Cells↗

PubMed2000

Intracellular pH in one-cell mouse embryo differs between subcellular compartments and between interphase and mitosis.

The pH-sensitive dual-emission fluorophore SNARF-1 coupled with a laser confocal microspectrofluorimeter was used to measure the internal pH (pHi) in different subcellular and subnuclear compartments of early mouse embryos. By this method we analysed the first cell cycle of naturally fertilised embryos in order to detect possible pHi changes correlated to cellular events, particularly the onset of replication or transcription and the first mitosis. Throughout interphase, significant differences of pHi were observed between cytoplasm and pronuclei, and, even more striking, between these compartments and nucleolus precursor bodies, whose pHi was systematically lower. We could detect significant pHi change neither during the replication phase nor at the onset of zygotic transcription, but pHi increased at the end of the one-cell stage in both cytoplasm and chromatin regions, a process that seemed specifically correlated with mitosis.

Animals↗

PubMed1997

Haploid maternal genome derived from early diplotene oocytes can substitute for the female pronucleus in preimplantation mouse development.

We describe the preimplantation development of mouse embryos that have received the haploid maternal genome derived from early diplotene nuclei of primordial oocytes (PO). Two generations of recipient egg-cells were used. Induction of two meiotic divisions of the PO nucleus and the reduction of the number of chromosomes to the haploid level were achieved in preovulatory oocytes (primary recipients). The developmental potential of the obtained haploid genome was examined in zygotes (secondary recipients). The nuclei of PO obtained from newborn mice were transferred by cell electrofusion to in vitro maturing (IVM) and enucleated preovulatory mouse oocytes. The reconstructed oocytes which had completed maturation, i.e., reached metaphase II, were artificially activated (8% ethanol + CHX). Activated oocytes were used as donors of haploid pronuclei of PO origin which were transferred (by karyoplast fusion) to partially enucleated zygotes containing only the male pronucleus. Thus, reconstituted zygotes were transplanted to the ligated oviducts of the cycling mice and 27% of them developed to the blastocyst stage. Our experiments demonstrate that 1) the nucleus of PO can be induced to premature meiotic divisions in an IVM enucleated preovulatory oocyte; 2) in the presence of a normal male pronucleus, the haploid pronucleus of PO origin can substitute for a female pronucleus during preimplantation development.

Animals↗

PubMed1994

Development of rat x mouse hybrid embryos produced by microsurgery.

Experimental production of hybrid embryos between Mus musculus L. and Rattus norvegicus L. was achieved by nuclear transplantation using both ovulated oocytes in metaphase II and pronuclear zygotes. Recipient egg-cells were of mouse origin in all cases. The developmental potential of hybrids was examined in vivo. Nucleo-cytoplasmic hybrids resulting from the introduction of rat metaphase II chromosomes into enucleated mouse oocytes, which were subsequently activated, were regularly blocked at the 1- or 2-cell stage. Nuclear (genetic) hybrids produced by transfer of a rat nucleus (in the form of metaphase II chromosomes or a pronucleus) into a nucleated mouse recipient (oocyte or zygote) were capable of development to the 5- to 8-cell stage. Transplantation of rat cytoplasm alone to intact metaphase II oocytes, followed by oocyte activation, generated cytoplasmic hybrids which developed to the morula stage. In control experiments (nuclear transfer between mouse oocytes or zygotes), a high proportion of embryos formed morulae and blastocysts. These results demonstrate that the rat nucleus is incapable of functioning in mouse cytoplasm, that introduction of the rat genome into intact mouse egg-cells impairs normal development, and that transfer of foreign (rat) cytoplasm into mouse egg-cells affects preimplantation development of manipulated embryos.

Animals↗

PubMed1986

Chromosome condensation activity in ovulated metaphase II mouse oocytes assayed by fusion with interphase blastomeres.

Fusion of large and small karyoplasts produced from metaphase II mouse oocytes with interphase blastomeres from 2-cell and 8-cell embryos (volume ratio of partners, 1:1) results in premature chromosome condensation (PCC) of the interphase nucleus in the majority of the fusion products (hybrids). Fused under the same experimental protocol, oocyte-derived cytoplasts also induce PCC of the blastomere nucleus in the fusion products (cybrids) provided they originate from recently ovulated oocytes (141/2-15 h after injection of human chorionic gonadotrophin (HCG)). In cytoplasts derived from older oocytes (16-20 h post-HCG) chromosome condensation activity gradually decreases with time as can be inferred from the increasing proportion of cybrids retaining interphase blastomere nuclei. However, even the oldest cytoplasts (19-20 h post-HCG) can induce PCC if the cytoplast volume significantly exceeds the volume of the interphase partner (7:1). We postulate that the condensation activity is predominantly bound to the nuclear apparatus (most probably to the chromosomes), and that in the cytoplasm of metaphase II mouse oocyte it decreases with post-ovulatory age.

Animals↗

PubMed1984

Autonomous cortical activity in mouse eggs controlled by a cytoplasmic clock.

Mouse eggs of Swiss albino origin, both parthenogenetic and fertilized, were bisected into nucleate (NHs) and anucleate halves (AHs) and observed in vitro (semicontinuous observations) for up to 40 h for possible manifestations of cortical activity. Three experimental groups were studied: (1) Non-fertilized eggs activated 17 h after administration of hCG with a heat-shock and bisected 4 h later. (2) Non-fertilized eggs first bisected, and the resulting sister halves activated 17 h after administration of hCG with ethyl alcohol. (3) In vivo fertilized eggs bisected 27 h after administration of hCG into an AH and a binucleate half. Parthenogenetic eggs (intact, zona-free, and incompletely bisected), and fertilized eggs collected 17, 20, and 27 h after administration of hCG were also studied. In the middle of the first cell cycle the cell surface in all types of cells studied changed from smooth to slightly undulate. In nucleate cells the surface deformations lasted for several hours and disappeared shortly before the first mitosis. In contrast, in AHs the indentations of the cell surface deepened, and developed into manifold furrows, thus leading to fragmentation. However, in 20% of AHs fragmentation was partially or completely reversed. The incidence and the intensity of fragmentation were lower, and its reversibility was more common in AHs carrying the 2nd polar body. We suggest that the interphase nucleus, i.e. the pronucleus in whole eggs and NHs, and the 2nd polar body nucleus (if 2nd polary body is attached to an AH) exerts a moderating effect on cortical activity. However, the initiation of cortical activity is nucleus-independent, as shown by the behaviour of AHs separated before activation. We believe that the observed phenomena reflect autonomous cortical activity which is regulated by a cytoplasmic clock.

Animals↗