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PubMed2001

From oocyte maturation to the in vitro cell cycle: the history of discoveries of Maturation-Promoting Factor (MPF) and Cytostatic Factor (CSF).

This article briefly reviews the classical cell cycle studies using oocytes and zygotes of mainly amphibians in the past century. The discussions are focused on the investigations into the cytoplasmic factors that regulate meiosis during oocyte maturation and the initiation of mitosis during fertilisation, which were carried out in the author's lab between 1967 and 1987. This chronicle traces the development of the problems and the direction in which their solutions were attempted in the course of these investigations. The author tries to answer the following questions: why he decided to study oocyte maturation, how he discovered progesterone as a maturation-inducing hormone, how he discovered and characterised the cytoplasmic regulators of the cell cycle, Maturation-Promoting Factor (MPF) and Cyto-Static Factor (CSF), and how he invented the method of observing cell cycle processes in a cytoplasmic extract in vitro.

Animals↗
PubMed1991

Ontogeny of T cell maturation in LEC mutant rats which bear a congenital arrest of maturation from CD4+CD8+ to CD4+CD8- thymocytes.

LEC rats bear a congenital deficiency in CD4+CD8- thymocytes and peripheral CD4+ T cells, and consequently a deficiency in Th cell functions. Ontogeny of T cell maturation in normal and LEC mutant rats was, therefore, investigated. Prenatal development of thymocytes in normal rat strains, with respect to the expression of CD4/CD8 and TcR antigens, was similar to that of mice except that its kinetics was delayed by approximately 24 h. The kinetics of T cell maturation in LEC rats was comparable with that of normal rats up to day 19 of gestation, at which stage double-negative thymocytes (CD4-CD8-) developed into double positives (CD4+CD8+) through immature CD4-CD8+ subset. At day 19 of gestation in LEC as well as normal rats, double positives occupied approximately 80% of the total thymocytes, half of which were TcR-dull positive, indicating that TcR was normally rearranged and then expressed in LEC rat thymocytes. These data indicate that double negatives normally mature into at least double positives in LEC rats. Both single positives appeared after day 19 of gestation in normal rats, while in LEC rats CD4+CD8- cells did not appear, suggesting that the deficiency in CD4+CD8- cells is due to a congenital arrest of maturation from CD4+CD8+ to CD4+CD8- cells, but not due to a postnatal deletion.

Age Factors↗
PubMed1977

Studies related to the head-maturation pathway of bacteriophages T4 and T2:I. morphology and kinetics of intracellular particles produced by mutants in the maturation genes.

Mutants in the genes governing the maturation of the head of bacteriophage T4 and in gene 24 were studied by electron microscopy of thin sections. We define morphologically: black particles, comprising mature, stable heads and immature, fragile heads, which break down upon lysis; grizzled particles, which apparently are partially filled or partially emptied; empty large particles without DNA or core which are all the same size as normal heads; empty small particles without DNA and without core which are of the size of the tau particle, which is the prehead of phage T4. The study of single and double mutants of the maturation genes demonstrates that the phenotypes are only different by the proportions of the different particles made except for 17- where only empty small and empty large particles accumulate. The mutants in gene 24 are epistatic on all other mutants. Mutants in gene 17 are epistatic on the remaining ones. The results are consistent with the hypothesis that the products of several of the maturation genes act on DNA to render it competent for packaging while the others act directly on the particle. By this uncoupling, bypasses and abortive pathways can result.

Coliphages↗
PubMed1999

Induction of ovulation of mature oocytes by the maturation-inducing steroid 17,20beta,21-trihydroxy-4-pregnen-3-one in the spotted seatrout.

Incubation of mature, hydrated, follicle-enclosed oocytes of the spotted seatrout, Cynoscion nebulosus, with the maturation-inducing steroid (MIS), 17,20beta,21-trihydroxy-4-pregnen-3-one (20beta-S), for 9-12 h resulted in the appearance of ovulated oocytes in the culture media. The ovulation response was concentration-dependent and steroid-specific. The other teleost MIS, 17, 20beta-dihydroxy-4-pregnen-3-one (17,20beta-P), was also a potent inducer of ovulation, whereas progesterone and 11-deoxycorticosterone did not stimulate ovulation above control levels and partially antagonized the action of 20beta-S. The agonist and antagonist activities of these steroids on ovulation are consistent with their relative binding affinities for the ovarian nuclear progestogen receptor previously characterized in this species. Both the RNA synthesis inhibitor actinomycin D and the protein synthesis inhibitor cycloheximide blocked MIS-induced ovulation. This suggests that induction of ovulation by the MIS is through a genomic mechanism of action, and potentially involves the previously characterized nuclear progestogen receptor. Gonadotropin (hCG)-induced ovulation was blocked by addition of the steroid synthesis inhibitor cyanoketone, which was overcome by the addition of 20beta-S, but not pregnenolone. Thus, the most likely mechanism of gonadotropin-induced ovulation is an increase in the synthesis of the MIS. It is concluded that the processes of final oocyte maturation and ovulation are both regulated by the MIS. Whereas final oocyte maturation is mediated by the 20beta-S membrane receptor (P. Thomas and S. Das, 1997, Biol. Reprod. 57, 999-1007), ovulation is regulated by a genomic mechanism and is potentially mediated by the previously characterized nuclear progestogen receptor.

Animals↗
PubMed1979

The ultrasonic changes in the maturing placenta and their relation to fetal pulmonic maturity.

A practical classification of placental maturity changes has been developed based on a review of multiple ultrasound evaluations of placental texture over a 4 year period. This classification grades placentas from 0 to 3 according to specific ultrasonic findings at the basal and chorionic plates as well as within the substance of the organ itself. The placentas of 129 patients were graded according to this system at the time of ultrasound evaluation. Eighty-six patients had placentas classified as Grade 1 or greater and all of these had lecithin-sphingomyelin (L/S) ratio determinations performed. Mature L/S ratios (2.0) were found in 68% of Grade I (21/31), 88% of Grade II (28/32), and 100% of Grade III placentas (23/23). These results suggest a correlation between maturational changes of the placenta as seen by ultrasound and fetal pulmonic maturity as indicated by L/S ratio.

Amniotic Fluid↗
PubMed1979

Amniotic fluid lecithin/sphingomyelin ratio, palmitic acid, palmitic acid/stearic acid ratio, total cortisol, creatinine, and percentage of lipid-positive cells in assessment of fetal maturity and fetal pulmonary maturity: a comparison.

Lecithin/sphingomyelin (L/S) ratio, creatinine, percentage of lipid-positive cells, palmitic acid, palmitic acid/stearic acid (P/S) ratio, and total cortisol were analyzed as tests for fetal maturity and fetal pulmonary maturity in 164 samples of amniotic fluid from 121 patients. Fifty samples were taken within 72 hours of delivery. The best tests for fetal maturity (37 weeks) with differential percentages were L/S ratio, palmitic acid, and P/S ratio. In the assessment of fetal pulmonary maturity, we studied an additional 174 samples in which only L/S ratio, creatinine, and lipid-positive cells were analyzed. All tests showed a high predictive value of an immature (positive) result was much less for all six parameters; the three best tests were total cortisol (33%), lipid-positive cells (26%) and L/S ratio (14%).

Amniotic Fluid↗
PubMed1988

Regulation of meiotic metaphase by a cytoplasmic maturation-promoting factor during mouse oocyte maturation.

During mouse oocyte maturation the regulation of the activity of a cytoplasmic maturation-promoting factor (MPF) was examined. The mouse MPF activity was determined based on its ability to induce maturation in immature starfish oocytes after microinjection with the cytoplasm from mouse oocytes. MPF appeared initially at germinal vesicle breakdown (GVBD), and its activity fluctuated in exact correspondence with meiotic cycles, reaching a peak at each metaphase and almost disappearing at the time of emission of the first polar body. Cycloheximide affected neither the initial MPF appearance nor GVBD. Thereafter, however, in the presence of cycloheximide the meiotic spindle was not formed and MPF disappeared, although the chromosomes remained condensed. After removing cycloheximide, MPF reappeared and was followed by the first metaphase and subsequently by polar body emission. Finally the meiotic cycle progressed to the second metaphase. Thus, for the appearance of MPF, there is a critical period shortly before the first metaphase, after which protein synthesis is required. In the presence of either cytochalasin D or colcemid, MPF activity remained at elevated levels. Addition of cycloheximide to such cytochalasin-treated oocytes, in which the meiotic cycle was arrested at the first metaphase, caused the MPF levels to decrease and was followed by movement of chromosomes to both poles where they decondensed and two nucleus-like structures were formed. Thus, the disappearance of MPF may initiate the metaphase-anaphase transition. Furthermore, detailed cytological examination revealed that chromosomes in cytochalasin-treated oocytes were monovalent while those treated only with cycloheximide were divalent, suggesting that dissociation of the synapsis is a prerequisite for chromosome decondensation after the disappearance of MPF. In all these respects, MPF seems to be a metaphase-promoting factor rather than just a maturation-promoting factor.

Animals↗
PubMed1985

Maturation of rabbit reticulocytes: susceptibility of mitochondria to ATP-dependent proteolysis is determined by the maturational state of reticulocyte.

A simple procedure is described to separate reticulocytes of different maturity in high yield. It is shown that exhaustion of supply of mitochondria susceptible to degradation by the lipoxygenase-ATP-dependent proteolysis system limits the extent of breakdown of mitochondria during in vitro maturation. The susceptibility of mitochondria depends on the maturity of the reticulocytes. Incubation in the presence of calcium ions and calcium ionophore leads to full susceptibility of mitochondria in immature reticulocytes but has no effect on those in mature reticulocytes which are already fully susceptible to degradation. Conditions which lead to rapid degradation of mitochondria do not affect the behaviour of the reticulocyte count. There appears to be no obligatory connection between the breakdown of mitochondria and of ribosomes.

Adenosine Triphosphate↗
PubMed1977

The relationship between accelerated pulmonary maturity and accelerated neurological maturity in certain chronically stressed pregnancies.

Two studies were done. In the first, 51 infants from high-risk pregnancies were evaluated for accelerated clinical neurological maturation. Eight infants had accelerated neurological maturation 3 or more weeks in excess of gestational age. In the second study, a sample of 25 infants with documented acceleration of pulmonary surfactant (lecithin/sphingomyelin ratio greater than or equal to 2 at gestational age less than or equal to 32 weeks) all infants showed accelerated neurological maturation (range 3 to 8 weeks) with the conditions studied associated with accelerated pulmonary maturation (for instance, retroplacental bleeding, prolonged rupture of membranes, placental infarction, severe toxemia, hypertensive disease, circumvallation, and amnionitis). Chronic retroplacental bleeding was associated with the most dramatic pulmonary and neurological accelerations.

Birth Weight↗
PubMed2003

In vitro maturation of bovine cumulus-oocyte complexes in undiluted follicular fluid: effect on nuclear maturation, pronucleus formation and embryo development.

Since resumption of meiosis and cytoplasmic maturation of bovine oocytes takes place in close association with follicular fluid, it would be logical to assume that this might be a perfect maturation medium. To test the hypothesis, abattoir-derived cumulus-oocyte complexes (COCs) were in vitro matured in undiluted (i) mixed follicular fluid (FF) from 3 to 15 mm follicles from abattoir ovaries, (ii) preovulatory follicular fluid (POF) from the dominant follicle from a cyclic unstimulated heifer, (iii) preovulatory follicular fluid (OPU) from synchronised and superovulated heifers 60 h after prostaglandin and 20 h after GnRH treatment, and in (iv) TCM-199 with 5% serum. Subsequent to IVM, the COC were subjected to IVF and IVC, and embryo development was followed until the blastocyst stage at Day 8 after insemination. The MII rates in the TCM-199 (69%), POF (69%) and OPU (72%) groups were not different from each other but different from the FF (41%) group (P<0.05). In spite of the high MII rates, none of the follicular fluids supported embryo development: the FF, POF and OPU blastocyst rates were alike (3%, 3%, 2%) and different (P<0.05) from the rates in the TCM-199 (19%). During IVM in follicular fluids but not in TCM-199, the expanded cumulus masses became trapped in a coagulum. Although it could be prevented by the presence of heparin during IVM, it did not improve the blastocyst rates. In conclusion, undiluted preovulatory follicular fluids supported nuclear maturation but not further embryonic development as judged by the high MII and low blastocyst rates.

Animals↗
PubMed1978

Involvement of the mature domain in the in vitro maturation of Bacillus subtilis precursor 5S ribosomal RNA.

A precursor of 5S ribosomal RNA from Bacillus subtilis (p5A rRNA, 179 nucleotides in length) is cleaved by RNase M5, a specific maturation endonuclease which releases the mature 5S rRNA (m5, 116 nucleotides) and precursor fragments derived from the 5' (21 nucleotides) and 3' (42 nucleotides) termini of p5A rRNA. Previous results (Meyhack, B., et al. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 3045) led to the conclusion that recognition elements in potential RNase M5 substrates mainly reside in the mature moiety of the precursor. Limited digestion of p5A rRNA with RNase T1 permitted the isolation of a number of test substrates which contained both precursor-specific segments and were unaltered in the immediate vicinity of the cleavage sites, but which differed in that more or less extensive regions of the mature moiety of the p5A rRNA were deleted. Tests of the capacity of these partial molecules to serve as substrates for RNase M5 indicate clearly that the enzyme recognizes the overall conformation of potential substrates, neglecting only the double-helical "prokaryotic loop" (Fox, G.E., & Woese, C.R. (1975) Nature (London) 256, 505).

Bacillus subtilis↗
PubMed1983

Immunocytochemical localization of prosomatostatin fragments in maturing and mature secretory granules of pancreatic and gastrointestinal D cells.

Pancreatic and gastrointestinal D cells were examined by immunocytochemistry using antisera against somatostatin-28 (SS28) and its NH2-terminal fragment SS28-(1-12), followed by the staphylococcal protein A-gold (pAg) complex. In pancreatic and gastric D cells incubated with antiserum against SS28-(1-12) the gold particles produced intense staining of the mature secretory granules but weaker staining of the immature granules associated with the Golgi area, whereas after SS28 antiserum treatment the particles accumulated selectively over the population of immature secretory granules. In intestinal D cells not only SS28-(1-12) but also SS28 antiserum produced an intense gold staining over the mature delta granules. These observations show that the relative amounts of immunoreactive sites related to SS28 and its cleavage product SS28-(1-12) in maturing and mature secretory granules are different in pancreatic, gastric, and intestinal D cells.

Humans↗
PubMed2004

Estradiol and its membrane-impermeable conjugate (estradiol-bovine serum albumin) during in vitro maturation of bovine oocytes: effects on nuclear and cytoplasmic maturation, cytoskeleton, and embryo quality.

In various cell types, there is increasing evidence for nongenomic steroid effects, i.e., effects that are not mediated via the classical steroid receptors. However, little is known about the involvement of the nongenomic pathway of estradiol (E2) on mammalian oocyte in vitro maturation (IVM). The aim of this study was to investigate whether the effects of E2 on bovine oocyte IVM are mediated via a plasma membrane receptor (nongenomic). First, we investigated the expression of estradiol (classical) receptor alpha (ERalpha) and beta (ERbeta) mRNA in oocytes and cumulus cells (CC). We also studied the effects of different exposure times to E2 (before and after germinal vesicle breakdown, GVBD) on nuclear maturation. To study the possible involvement of the putative estradiol plasma membrane receptor on the IVM of oocytes, we used E2 conjugated with bovine serum albumin (E2-BSA), which cannot cross the plasma membranes. Our results demonstrate that oocytes expressed ERbeta mRNA, while CC expressed both ERalpha and ERbeta mRNA. Exposure to E2 during the first 8 h of culture (before GVBD) induced a block at the metaphase I stage (MI). However, the presence of E2 after GVBD induced an increase of oocytes with nuclear aberrations. Meiotic spindle organization was severely affected by E2 during IVM and multipolar spindle was the most frequently observed aberration. Exposure of oocytes to E2-BSA did not affect nuclear maturation, blastocyst formation rate, nor embryo quality. Our results suggest that the detrimental effects of E2 on in vitro nuclear maturation of bovine oocyte are not exerted via a plasma membrane receptor.

Animals↗
PubMed2007

A newly established murine immature dendritic cell line can be differentiated into a mature state, but exerts tolerogenic function upon maturation in the presence of glucocorticoid.

The phenotype and function of murine dendritic cells (DCs) are primarily studied using bone-marrow-derived DCs (BM-DCs), but may be hampered by the heterogeneous phenotype of BM-DCs due to their differential state of maturation. Here we characterize a newly established murine DC line (SP37A3) of myeloid origin. During maintainance in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and M-CSF, SP37A3 cells resemble immature DCs characterized by low expression of major histocompatibility complex (MHC) II and costimulatory molecules and low T-cell stimulatory capacity. Upon stimulation, SP37A3 cells acquire a mature phenotype and activate naive T cells as potently as BM-DCs. Similar to BM-DCs, SP37A3 cells activated in the presence of dexamethasone-induced regulatory T cells, which were anergic upon restimulation and suppressed proliferation of naive T cells. This tolerogenic state was reflected by lower expression levels of costimulatory molecules and proinflammatory cytokines compared with mature cells, as well as up-regulated expression of FcgammaRIIB and interleukin-1RA (IL-1RA). SP37A3 cells were responsive to dexamethasone even when applied at later time points during activation, suggesting functional plasticity. Thus, DC line SP37A3 represents a suitable model to study functions of immature and mature as well as tolerogenic myeloid DCs, circumventing restrictions associated with the use of primary DCs and BM-DCs.

Animals↗
PubMed1992

Skeletal maturity, dental maturity, and eruption in young patients with Turner syndrome.

A major problem for patients with Turner syndrome is their small body height. The rapid biotechnologic development has now made treatment with growth hormone possible at a larger scale. The aim of this investigation was to evaluate skeletal maturity, dental maturity, and eruption in a group of young patients before hormone therapy. The material comprised 33 patients aged 7-16.7 years. The skeletal maturity, as judged from hand radiographs, was on an average 2.3 years retarded (p < 0.001) and showed increasing retardation with increasing age. The dental maturity, assessed from the formation stages of the permanent teeth on panoramic radiographs, was accelerated, with a mean value of 1 year (p < 0.001). The timing of clinical eruption did not differ significantly from that of our reference material; the Turner girls were on an average 3.7 months ahead. Several patients had local eruption problems, especially in the maxillary lateral segments. It is suggested that disharmony between tooth size and arch size may contribute to this problem.

Adolescent↗
PubMed1993

PNA lectin-based separation of thymocytes into mature and immature subpopulations: CD4-8- double negative cells display characteristics of PNAlo mature thymocytes.

Cortical (immature) thymocytes are widely reported to express intermediate to high levels of receptors for the lectin, peanut agglutinin (PNA). Light-scatter studies of murine fetal thymocytes stained with PNA or anti-mouse CD4 and CD8 monoclonal antibodies indicated, however, that the most immature CD4-8- (DN) thymocyte subpopulation binds levels of PNA commonly described as PNAlo. Evaluation of the PNA binding characteristics of fetal thymocytes negative for the CD8 antigen confirmed the existence of a major population (approximately 20% of total cells) of CD4-8- PNAlo fetal thymocytes. The majority of these DN thymocytes were subsequently found to bind sub-agglutinating levels of PNA, similar to mature CD4+ or CD8+ single positive (SP) thymocytes. Given this information, an immunomodulating compound (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) known to produce a maturational delay in murine thymocytes was tested for a possible concurrent effect on thymocyte PNA lectin binding. A TCDD-induced increase in DN thymocytes was found to be paralleled by an increase of equal magnitude in PNAlo thymocytes. Taken together, these data provide evidence that acquisition of the PNA receptor may be a maturational event occurring during the DN stage of thymocyte ontogeny. Further, these results suggest that separation of thymocytes into mature (medullary) and immature (cortical) subpopulations by PNA agglutination may result in contamination of medullary cells by the most immature (DN) subpopulation of thymocytes.

Animals↗
PubMed1975

Progesterone-induced in vitro maturation in oocytes of Notophthalmus viridescens (Amphibia Urodela) and some observations on cytological aspects of maturation.

Maturation in vitro of oocytes of the newt, Notophthalmus viridescens, is inducible with progesterone after in vivo treatment of females with gonadotropin; few oocytes mature in vitro in the absence of such gonadotropin treatment. Chromosomes of most large oocytes of animals not receiving gonadotropin are still in the lampbrush condition; chromosomes from gonadotropin-treated animals are shorter and the lateral loops are less profuse and somewhat retracted. The chromosome condition, then, can be correlated with susceptibility to progesterone induction of maturation in vitro. As maturation progresses, the germinal vesicle moves toward the surface and decreases in size, with an apparent loss of nuclear material from the centripetal end. Although lateral loops of most chromosomes disappear during the changes in the germinal vesicle, profuse loops develop during this period at the sphere loci, which were previously devoid of loops.

Animals↗
PubMed1986

Responses of 'mature' human B lymphocyte lines to inducers of maturation and activation.

Four human B cell lines with a mature phenotype (immunoglobulin secretion and expression of membrane markers associated with maturation) were cultured in the presence of phorbol ester (PMA), dimethyl sulphoxide (DMSO) and two conditioned media. PMA and DMSO led to changes in phenotype which suggested the cells were being activated, whilst the conditioned media resulted in increased immunoglobulin secretion, accompanied by phenotypic changes more consistent with maturation towards the plasma cell stage. The four cell lines, which had different origins (EBV-transformed normal B cell, Burkitt's lymphoma, prolymphocytic leukaemia and multiple myeloma) responded differently to the culture stimuli. These differences suggest that the changes associated with transformation affect the way in which these cells respond to agents which stimulate activation and maturation.

B-Lymphocytes↗