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At least 181 records · Page 10Linked to original sources
PubMed2001

Strain-dependent high-level expression of a transgene for manganese superoxide dismutase is associated with growth retardation and decreased fertility.

Manganese superoxide dismutase (MnSOD) is essential in protecting mitochondria against the damaging effects of superoxide radicals (O(2)(*-)), and increased expression of MnSOD protects cells and transgenic animals from various forms of oxidative stress. In addition, increased levels of MnSOD have been shown to slow down cell growth and induce differentiation. To study the effects of high MnSOD levels in vivo, we generated a series of transgenic mice using a mouse genomic sequence under control of the endogenous promoter. Four transgenic lines produced by pronuclear DNA injection exhibited up to 2-fold elevated MnSOD levels in brain and heart. However, using an embryonic stem cell approach, a line having 10-fold elevated MnSOD levels in the brain and 6- to 7-fold elevated levels in the heart and kidney was generated. Surprisingly, the genetic background of this transgenic line influenced the expression level of the transgene, with DBA/2 (D2) and C57BL/6 (B6) mice exhibiting low- and high-level transgene expression, respectively. This difference was the result of an increased transcription rate of the transgene. High-level MnSOD expression in B6 animals was associated with small size, male infertility, and decreased female fertility. These features are absent on the D2 background and indicate that high levels of MnSOD activity may interfere with normal growth and fertility.

Animals↗
PubMed1997

Two successful pregnancies in a 46,XY patient.

Two successful pregnancies (singleton followed by twins) following ovum donation/in-vitro fertilization in a 46,XY woman have been studied. Although similar cases have previously been presented: in a pure XY patient and in a 45,X/46,XY patient, this case is one in which a subsequent successful pregnancy has resulted. In such patients, the rate of Caesarean section appears to be increased, and we postulate that the hypoplastic nature of the uterus, although able to respond quite well to both exogenous and endogenous hormones to accept and maintain a pregnancy, may lack the capability to respond fully in labour by dilating appropriately.

Adult↗
PubMed2003

Involvement of calcium/calmodulin-dependent protein kinase II (CaMKII) in meiotic maturation and activation of pig oocytes.

Calcium signal is important for the regulation of meiotic cell cycle in oocytes, but its downstream mechanism is not well known. The functional roles of calcium/calmodulin-dependent protein kinase II (CaMKII) in meiotic maturation and activation of pig oocytes were studied by drug treatment, Western blot analysis, kinase activity assay, indirect immunostaining, and confocal microscopy. The results indicated that meiotic resumption of both cumulus-enclosed and denuded oocytes was prevented by CaMKII inhibitor KN-93, Ant-AIP-II, or CaM antagonist W7 in a dose-dependent manner, but only germinal vesicle breakdown (GVBD) of denuded oocytes was inhibited by membrane permeable Ca2+ chelator BAPTA-AM. When the oocytes were treated with KN-93, W7, or BAPTA-AM after GVBD, the first polar body emission was inhibited. A quick elevation of CaMKII activity was detected after electrical activation of mature pig oocytes, which could be prevented by the pretreatment of CaMKII inhibitors. Treatment of oocytes with KN-93 or W7 resulted in the inhibition of pronuclear formation. The possible regulation of CaMKII on maturation promoting factor (MPF), mitogen-activated protein kinase (MAPK), and ribosome S6 protein kinase (p90rsk) during meiotic cell cycles of pig oocytes was also studied. KN-93 and W7 prevented the accumulation of cyclin B and the full phosphorylation of MAPK and p90rsk during meiotic maturation. When CaMKII activity was inhibited during parthenogenetic activation, cyclin B, the regulatory subunit of MPF, failed to be degraded, but MAPK and p90rsk were quickly dephosphorylated and degraded. Confocal microscopy revealed that CaM and CaMKII were localized to the nucleus and the periphery of the GV stage oocytes. Both proteins were concentrated to the condensed chromosomes after GVBD. In oocytes at the meiotic metaphase MI or MII stage, CaM distributed on the whole spindle, but CaMKII was localized only on the spindle poles. After transition into anaphase, both proteins were translocated to the area between separating chromosomes. All these results suggest that CaMKII is a multifunctional regulator of meiotic cell cycle and spindle assembly and that it may exert its effect via regulation of MPF and MAPK/p90rsk activity during the meiotic maturation and activation of pig oocytes.

Animals↗
PubMed2003

Generation and characterization of a transgenic mouse with a functional human TSPY.

To generate an animal model that is suitable for the analysis of regulation and expression of human testis-specific protein, Y-encoded TSPY, a transgenic mouse line, TgTSPY9, harboring a complete structural human TSPY gene was generated. Fluorescence in situ hybridization and Southern analyses show that approximately 50 copies of the human TSPY transgene are integrated at a single chromosomal site that maps to the distal long arm of the Y chromosome. The transgene is correctly transcribed and spliced according to the human pattern and is mainly expressed in testicular tissue, with spermatogonia and early primary spermatocytes (leptotene and zygotene) as expressing germ cells. TSPY transgenic mice are phenotypically normal, and spermatogenesis is neither impaired nor enhanced by the human transgene. The present study shows that a human TSPY gene integrated into the mouse genome follows the human expression pattern although murine tspy had lost its function in rodent evolution millions of years ago.

Animals↗
PubMed2004

Similar time restriction for intracytoplasmic sperm injection and round spermatid injection into activated oocytes for efficient offspring production.

The injection of male haploid germ cells, such as spermatozoa and round spermatids, into preactivated mouse oocytes can result in the development of viable embryos and offspring. However, it is not clear how the timing of intracytoplasmic sperm injection (ICSI) and round spermatid injection (ROSI) affects the production of offspring. We carried out ICSI and ROSI every 20 min for up to 4 h after the activation of mouse oocytes by Sr(2+) and compared the late-stage development of ICSI- and ROSI- treated oocytes, including the formation of pronuclei, blastocyst formation, and offspring production. The rate of pronucleus formation (RPF) after carrying out ICSI started to decrease from >95% at 100 min following oocyte activation and declined to <20% by 180 min. In comparison, RPF by ROSI decreased gradually from >70% between 0 and 4 h after activation. The RPFs were closely correlated with blastocyst formation. Offspring production for both ICSI and ROSI decreased significantly when injections were conducted after 100 min, a time at which activated oocytes were in the early G1 stage of the cell cycle. These results suggest that spermatozoa and round spermatids have different potentials for inducing the formation of a male pronucleus in activated oocytes, but ICSI and ROSI are both subject to the same time constraint for the efficient production of offspring, which is determined by the cell cycle of the activated oocyte.

Animals↗
PubMed2005

The capability of reprogramming the male chromatin after fertilization is dependent on the quality of oocyte maturation.

The present experiments compared the ability of pig oocytes matured either in vivo or in vitro to structurally reorganize the penetrated sperm chromatin into male pronucleus (PN) and to carry out, in parallel, the epigenetic processes of global chromatin methylation and acetylation, 12-14 h after in vitro fertilization (IVF). In addition, PN distribution of histone deacetylase (HDAC), a major enzyme interfacing DNA methylation and histone acetylation, was investigated. The ability of the oocyte to operate an efficient block to polyspermy was markedly affected by maturation. The monospermic fertilization rate was significantly higher for in vivo than for in vitro matured (IVM) oocytes (P < 0.01) which, furthermore, showed a reduced ability to transform the chromatin of penetrated sperm into male PN (P < 0.01). Indirect immunofluorescence analysis of global DNA methylation, histone acetylation and HDAC distribution (HDAC-1, -2 and -3), carried out in monospermic zygotes that reached the late PN stage, showed that IVM oocytes also had a reduced epigenetic competence. In fact, while in about 80% of in vivo matured and IVF oocytes the male PN underwent a process of active demethylation and showed a condition of histone H4 hyperacetylation, only 40% of IVM/IVF zygotes displayed a similar PN remodelling asymmetry. Oocytes that carried out the first part of maturation in vivo (up to germinal vesicle breakdown; GVBD) and then completed the process in vitro, displayed the same PN asymmetry as oocytes matured entirely in vivo. A crucial role of HDAC in the establishment of PN acetylation asymmetry seems to be confirmed by the use of HDAC inhibitors as well as by the abnormal distribution of the enzyme between the two PN in IVM zygotes. Collectively, these data demonstrated that some pig IVM oocytes fail to acquire full remodelling competence which is independent from their ooplasmic ability to morphologically reorganize the sperm nucleus into PN.

Acetylation↗
PubMed2003

Pronuclear scoring. Time for international standardization.

Zygote scoring is an efficient tool for embryo selection not only in countries where embryo selection is not permitted. Several different scoring systems have been published so far, making comparisons of assessments between investigators and laboratories extremely difficult. Pronuclear evaluation should be standardized in a manner analogous to the standardization of cleavage stage embryo scoring or of semen evaluation by the World Health Organization. The ideal score should be clear and easily applicable. The items that have the greatest influence on embryonic development seem to be alignment and size of pronuclei, alignment and number of nucleoli, halo effect and appearance of vacuoles. These morphologic parameters can be observed in different features and can be summarized as a zygote score.

Adult↗
PubMed1990

[Techniques and indications of tubal transfer].

Intra-fallopian transfer of ovocytes and sperm, of zygotes at the two pronuclei stage or of embryos is a possible alternative to in vitro fertilization, at least when a fallopian tube is permeable. Its principle indications are unexplained or male infertility.

Embryo Transfer↗
PubMed1992

Embryo transfer to the uterus or the fallopian tube after in vitro fertilization yields similar results.

The outcome of ZIFT and IVF-ET was compared in consecutive nontubal factor patients in a prospective fashion. Groups did not differ in characteristics and were matched by the number of prezygotes/pre-embryos transferred. Overall, implantation, pregnancy, miscarriage, and ongoing PRs were not statistically different. These results suggest that ZIFT offers no significant advantage over IVF-ET for the treatment of nontubal infertility.

Adult↗
PubMed1990

[Curreny results of GIFT and ZIFT].

This report describes the results of gamete intra-fallopian transfer (GIFT) in 102 treatment cycles for male infertility and in 202 cycles for unexplained infertility. Twenty-one pregnancies out of 102 GIFT replacements (20.6 p. 100) were obtained in male infertility and 74 pregnancies out of 202 GIFT replacement (36.6 p. 100) were established. One hundred and forty-five pregnancies were obtained out of 348 zygote intra-fallopian transfers (ZIFT) (41 p. 100).

Embryo Transfer↗
PubMed1993

The effect of coculture on human zygote development.

It is well over a decade since the birth of the first test-tube baby and still the in-vitro conditions for early embryonic development remain suboptimal. The ideal culture medium to increase longevity and improve viability of human embryos is not available. Since the metabolic requirements of the human embryo changes from one cleavage stage to another, the development of a single culture medium for all stages could not be expected. The use of helper cells (coculture) in vitro offers much promise as there are numerous documentations in both man and animals describing their ability to increase blastulation rates and improve embryo viability. This paper reviews the effect of coculture on human zygote development. The selection and establishment of cell-lines, biologic actions of coculture of gametes and zygotes, the outcome, and future prospects are discussed.

Cell Line↗
PubMed1994

[Functioning conditions of laboratories dealing with cryopreservation of human pre-embryos].

The authors discuss about the functional conditions of the Human Reproductive Laboratories dealing with the cryopreservation of the human preembryos. They determine the safety specifications and recommend documentation of the cryopreservation based on their own practice. Finally they suggest the licensing-controlling system of the Human Reproductive Laboratories concerning cryopreservation of the human preembryos.

Cryopreservation↗