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PubMed1983

Nucleocytoplasmic distribution of snRNPs and stockpiled snRNA-binding proteins during oogenesis and early development in Xenopus laevis.

The distribution of small nuclear ribonucleoprotein particles containing U snRNAs (U snRNPs) during oogenesis and early development in Xenopus was analyzed with a lupus antibody (anti-Sm) that reacts with snRNA-binding proteins. Fully grown oocytes and embryos prior to gastrulation were found to be relatively depleted of U snRNPs in their nuclei and to contain an excess of snRNA-binding proteins stored in the cytoplasm. During late blastula-early gastrula, or after microinjection of U snRNAs into the cytoplasm of a mature oocyte, the proteins migrate into the nucleus. Dot hybridization analysis showed that small previtellogenic oocytes already contain a maximal amount of U1 (and U2) snRNAs, which then decreases to about 20% of that value in fully mature oocytes, even though the cell's volume has increased enormously. Thus fully grown oocytes and eggs accumulate snRNA-binding proteins for use during early development, but this is not coupled with the accumulation of U snRNA.

Animals↗

PubMed2004

Characterization of starch synthase I and II expressed in early developing seeds of kidney bean (Phaseolus vulgaris L.).

Plant starch synthase (SS) contributes to the elongation of glucan chains during starch biosynthesis and hence plays an essential role in determining the fine structure of amylopectin. To elucidate the role of SS activity in the formation of amylopectin in kidney bean (Phaseolus vulgaris L.), a study was undertaken to isolate cDNA clones for SS and to characterize the enzymatic properties of the coded recombinant enzymes. Two SS cDNAs, designated pvss1 and pvss21, which were isolated from early developing seeds, encoded SSI and SSII (designated PvSSI and PvSSII-1) that displayed significant identity (more than 65%) with other SSI and SSII members, respectively. RNA gel blot analysis indicated that both transcripts accumulate in leaves and developing seeds at the early stage. Immunoblot analysis with antisera raised against both recombinant proteins (rPvSSI and rPvSSII-1) showed that the accumulation of both proteins parallels the gene expression profiles, although both were detectable only in starch-granule fractions. Recombinant enzymes expressed by Escherichia coli cells showed distinct chain-length specificities for the extension of glucan chains. Our results suggest that these SS isozymes for synthesis of transitory starch are also responsible for synthesis of storage starch in early developing seeds of kidney bean.

Amino Acid Sequence↗

PubMed1994

A novel POU domain gene, zebrafish pou2: expression and roles of two alternatively spliced twin products in early development.

POU domain proteins are a large family of transcriptional regulatory proteins, many of which are implicated in the control of gene expression during early development. We describe here the cloning and expression of zebrafish pou2, a novel POU domain gene related to the mouse germ-line-specific transcription factor oct-3. Zebrafish pou2 is maternally expressed, and the transcripts are present from the one-cell stage to the gastrula stage. In situ hybridization analyses revealed that the transcripts were present in all blastomeres until the midblastula stage and that the expression was restricted to the epiblast during gastrulation. We found that alternatively spliced transcripts, t-pou2 RNAs, were also expressed in the embryos. In contrast to the Pou2 product, the t-Pou2 product lacks DNA-binding activity because of its incomplete POU domain structure. To examine the roles of the Pou2 and t-Pou2 products, we increased their expression in the embryo by microinjection of synthetic pou2 and t-pou2 RNAs into the fertilized eggs at the one-cell stage. Most embryos that developed from the eggs injected with pou2 RNA did not show any obvious developmental defects. In contrast, overexpression of the t-Pou2 product greatly affected the embryonic development: There was strong developmental retardation or arrest due to the incomplete gastrulation. In the affected embryos, expression of zebrafish T gene was reduced and the hypoblast formation was disturbed. Temporal and spatial expression patterns and the effects of overexpression of these products on development are consistent with the idea that the Pou2 and t-Pou2 proteins are involved in early development of zebrafish embryos. They may be involved in the proliferation of blastomeres in undetermined state at the blastula stage and/or the early cell commitment events at the gastrula stage. Also, our results indicate that different products generated as a result of alternative splicing from the same gene possess distinct functional capacities.

Alternative Splicing↗

PubMedDate not supplied

[Effect of millimeter waves on the early development of the mouse and sea urchin embryo].

The action of nonthermal electromagnetic radiation (EMR) of the millimeter range on the early development of murine and sea urchin embryos was investigated. An MRTA-01E-03 generator with a frequency of 54-78 GHz and radiation intensity of 0.06 mWt/cm2 was used. The embryos were irradiated during 30 min at the stage of two blastomeres. The number of murine embryos that reached the blastocyst stage increased (up to 97.3% in comparison with 87.5% in control). The total time of cultivation up to the blastocyst stage was also shorter (72 h) than in control (96 h). The irradiation had effect on the development of sea urchin embryos only if embryos with a weakened viability were tested. The results indicate that millimeter electromagnetic radiation has a stimulating effect on the early development of embryos, increasing the resistance of embryos to unfavorable environmental conditions.

Animals↗

PubMed1980

Calcium transport in small intestine during early development: role of vitamin D.

To define the role of vitamin D in calcium transport in the intestine during early development, female weanling rats were placed on vitamin D-replete or vitamin D-deficient diets, grown to maturity, and mated with normal males. Pups born to vitamin D-replete and vitamin D-deficient mothers were killed at various times after parturition, and calcium transport in the small intestine as well as the concentrations of calcium and phosphate in the plasma were measured. Transport of calcium in pups from vitamin D-replete and vitamin D-deficient litters was identical at 3 and 14 days postpartum but was threefold greater in pups from vitamin D-replete litters at weaning and 3 wk postweaning. 1,25-dihydroxyvitamin D3 had no effect on calcium transport at 14 days postpartum but did induce transport at weaning. Plasma concentrations of calcium at 3 days postpartum were nearly normal but decreased during the suckling period from 10.3 mg/100ml to 7.2 mg/100 ml in vitamin D-deficient rats. These results suggest that calcium transport in the intestine during early development is not mediated by vitamin D but that a vitamin D-sensitive transport system develops late in the suckling period.

Age Factors↗

PubMed2005

Embryonic-stage-dependent changes in the level of eIF4E-binding proteins during early development of sea urchin embryos.

The eukaryotic initiation factor 4E (eIF4E)-binding proteins (4E-BPs) inhibit translation initiation by binding eIF4E and preventing recruitment of the translation machinery to mRNA. We have previously shown that fertilization of sea urchin eggs triggers eIF4E-4E-BP complex dissociation and 4E-BP degradation. Here, we show that microinjection of eIF4E-binding motif peptide into unfertilized eggs delays the onset of the first mitosis triggered by fertilization, demonstrating that dissociation of the eIF4E-4E-BP complex is functionally important for the first mitotic division in sea urchin embryos. We also show by gel filtration analyses that eIF4E is present in unfertilized eggs as an 80 kDa molecular mass complex containing 4E-BP and a new 4E-BP of 40 kDa. Fertilization triggers the dissociation of eIF4E from these two 4E-BPs and triggers the rapid recruitment of eIF4E into a high-molecular-mass complex. Release of eIF4E from the two 4E-BPs is correlated with a decrease in the total level of both 4E-BPs following fertilization. Abundance of the two 4E-BPs has been monitored during embryonic development. The level of the two proteins remains very low during the rapid cleavage stage of early development and increases 8 hours after fertilization. These results demonstrate that these two 4E-BPs are down- and upregulated during the embryonic development of sea urchins. Consequently, these data suggest that eIF4E availability to other partners represents an important determinant of the early development of sea urchin embryos.

Animals↗

PubMed1992

Mitochondrial DNA content and mitochondrial gene transcriptional activities in the early development of loach and goldfish.

The mitochondrial DNA (mtDNA) content of the mature eggs and embryos of loach and goldfish at early developmental stages were detected by means of dot hybridization. The transcription of mitochondrial cytochrome oxidase subunit I and II (COI and COII) genes during their early development was also detected by Northern hybridization. The experimental results showed that the mtDNA content of the mature egg as well as that of the embryos during the period from fertilized egg up to hatching stage in both fishes is maintained at a constant level, giving an average value of 7.40 x 107 molecules or 1.33 ng for every embryo in loach and an average value of 1.87 x 10(8) molecules or 3.31 ng for every embryo in goldfish. In both fish embryos, the COI and COII transcripts declined gradually after fertilization until late-blastula stage and then increased in early gastrula stage. This indicated that the transcription of mitochondrial genomes of these two freshwater fishes, which belong to different families, might be activated at the beginning of gastrulation. The steady-state amounts of mitochondrial messenger transcripts existing in the embryos during the early development in both fishes seemed to be regulated by both their half-lives and the transcriptional level of the mitochondrial genomes. The results showed that the transcription of the mitochondrial genome in the early developmental process in loach and goldfish was not regulated by a gene dosage mechanism.

Animals↗

PubMed2002

Variations in DNA (cytosine-5)-methyltransferase-1 expression during oogenesis and early development of the zebrafish.

We report the determination of zebrafish DNA (cytosine-5-) methyltransferase ( dnmt-1) temporal and spatial patterns of expression in gonadal tissues and during early development. Only one dnmt-1 message of around 5 kb was observed in all tissues examined and its levels were highest in gonadal tissues. During the course of oogenesis, early oocytes contain significant amounts of dnmt-1 transcript while message abundance declines as oocytes mature. During early embryogenesis message levels remain low until the blastula stage. Methyltransferase enzyme assays reveal that the maternal dnmt-1 message accumulated during oogenesis is translated into protein presumably providing necessary dnmt-1 stockpiles to support early embryonic development prior to zygotic gene activation. Such spatial and temporal regulation of dnmt-1 expression suggests specific functions for the enzyme during oogenesis and early development of zebrafish.

Animals↗

PubMed2003

Early development destructive brain lesions and their relationship to epilepsy and hippocampal damage.

Fifty-one consecutive adult patients with epilepsy and early development destructive brain lesions were divided into three main groups according to the topographic distribution of the lesion on magnetic resonance imaging: hemispheric (H) (n=9); main arterial territory (AT) (n=25) and arterial borderzone (Bdz) (n=17). Eight (89%) patients from group H presented status epilepticus in the first 5 years of life, five of them associated with fever. Seventeen of the 25 patients from group AT (76%) had an obvious hemiparesis observed early in life. In addition, major prenatal events were significantly more common in the group AT compared with the other two groups. Among patients from group Bdz, prenatal or postnatal events were not identified, except for one patient. Conversely, nine patients from group Bdz (60%) showed a history of perinatal complications. Hippocampal atrophy (HA) was determined by visual analysis in 74.5% of all patients and by volumetry in 92%. The frequency of HA was comparable among groups, but patients from group H presented the most severe atrophy and more frequent hyperintense T2 hippocampal signal. In conclusion, these three groups of patients with early destructive lesions and epilepsy (H, AT and Bdz), appear to have distinct pathogenic mechanisms. Our data show that there is a striking association of HA with different patterns of neocortical destructive lesions of early development. This association seems to be related to a common and synchronic pathogenic mechanism. The recognition of the pattern and degree of HA among these patients with intractable seizures may influence the surgical rationale.

Adult↗

PubMed1995

Junctions between early developing osteoblasts of rat calvaria as revealed by freeze-fracture and ultrathin section electron microscopy.

Although intercellular junctions have been described between mature lamellar bone cells, little has been known about junctions between osteoblasts in early developing bone. We therefore conducted a freeze-fracture and ultrathin section study on developing calvaria of rat embryos aged 17-19 days to determine what types of intercellular junctions appear between osteoblasts in early osteogenesis. We observed that three main types of junctional structures, i.e., adherens of the macular type, gap, and focal tight junctions, coexist between osteoblasts in early developing bone. Their possible involvement in early morphogenetic events is discussed. Tight junctions are considered to be involved in compartmentalization of the early matrix and final polarization of osteoblasts.

Animals↗

PubMed1991

Effects of prenatal exposure to benzodiazepine-related drugs on early development and adult social behaviour in Swiss mice--III. Inverse agonists.

1. The present experiment examined, using a battery of tests, the effects of in utero exposure to the benzodiazepine inverse agonists DMCM and FG 7142 upon the early development and adult behaviour of Swiss Mice. 2. Early development was respectively retarded and augmented by treatments with the higher and lower doses of DMCM. FG 7142 suppressed later development. DMCM retarded righting reflex on certain days. FG 7142 had a significant, biphasic effect on eye opening. 3. Adult social behaviour was examined using the resident-intruder paradigm, by determining the time spent in broad behavioural categories. Male offspring of dams treated with DMCM showed increased threat. FG 7142 had no significant effects.

Animals↗

PubMed1992

Early development and X-chromosome inactivation in mouse parthenogenetic embryos.

Early development and X-chromosome inactivation were studied in ethanol-induced mouse parthenogenones. About 24% of oocytes transferred to 0.5-day pseudopregnant recipients successfully implanted. However, only 49%, 20%, and 16% of implanted parthenogenones survived 5, 6, and 7 days later, respectively. Abnormal development was evident in every parthenogenone as early as 5 days after activation with the degenerating polar trophectoderm. These embryos were destined to become either small disorganized embryos or embryonic ectoderm vesicles bounded by the visceral endoderm. Only 2 of 51 representative 6- to 8-day parthenogenones sectioned had morphology of the normal egg cylinder, although growth retardation was evident. Spontaneous LT/Sv parthenogenones shared similar morphological features. In late blastocysts, the frequency of cells with an apparently inactivated X chromosome was lower in parthenogenones than in fertilized embryos. The failure of X-inactivation in the trophectoderm seems to contribute to the defective development of parthenogenones.

Animals↗

PubMed1975

The early development of haploid and aneuploid parthenogenetic embryos.

The early development of parthenogenetically activated oocytes had been studied in C57BL X CBA-T6T6 (F1T6) translocation heterozygote mice and C57BL X CBA-LAC (F1LAC) mice. All F1T6 oocytes had either a quadrivalent or a univalent-trivalent configuration at meiosis I; no such chromosome configurations were observed in the F1LAC oocytes. At ovulation 36-5% of the F1T6 oocytes had 19 or 21 chromosomes, whereas 97% of the F1LAC had the normal haploid chromosome number of 20. After parthenogenetic activation, chromosome counts at metaphase of the first cleavage mitosis were made of the eggs with a single pronucleus following extrusion of the second polar body. These activated eggs had similar frequencies of 19, 20 and 21 chromosomes as had the oocytes at ovulation. The activated 1-cell eggs were transferred to the oviducts of pseudopregnant recipients and the embryos recovered 3 days later. At this stage of development, most of the F1T6 embryos with 19 chromosomes were no longer found, but the frequency of 21-chromosome embryos was similar to the frequency of 21-chromosome oocytes and activated eggs. There was a similar mean number of cells in the embryos with 20 and 21 chromosomes. The results indicate that nearly all the embryos with 19 chromosomes failed to develop, probably beyond the 2-cell stage, whereas oocytes with 21 chromosomes had a similar development of oocytes with 20 chromosomes up to the morula stage.

Aneuploidy↗

PubMed1980

Observations on the early development of embryos from repeat breeder heifers.

The early development of embryos collected from repeat breeder heifers after slaughter was studied using different methods; morphological appearance, number of cells and features in semithin sections of Epon embedded material. Embryos collected from virgin heifers were used as controls. The incidence of abnormal embryos was higher in the repeat breeder than in the virgin heifers. The abnormalities were mainly confined to cell organization. They could be seen already during the oviductal transit of the ova.

Animals↗

PubMed2006

[Polymorphism of genes of factors of hemostasis in patients with early development of ischemic heart disease.].

The review is devoted to analysis of data, related to contribution of genetic peculiarities of the hemostasis system to early development of ischemic heart disease (IHD). Information is presented on polymorphisms of tissue factor, coagulation factors VII, V, prothrombin, thrombomodulin, fibrinogen, thrombin activated fibrinolysis inhibitor, tissue plasminogen activator inhibitor, platelet membrane glycoproteines Ia, Iba, IIIa in patients with early development of IHD. Contradictoriness of existing data on effects of genetic heterogeneity of factors of hemostasis on risk of development of IHD at young age and necessity of further investigations in this area are underlined.

Coronary Artery Disease↗

PubMed1999

Multisequence MRI in clinically isolated syndromes and the early development of MS.

OBJECTIVE: To apply multisequence MRI techniques to patients with clinically isolated syndromes, to document the pattern and frequency of abnormalities at baseline and early follow-up, and to determine their predictive values for the early development of clinical MS. BACKGROUND: Disseminated lesions on T2-weighted brain MRI confer an increased risk of progression to clinically definite MS. Newer MRI techniques increase detection of lesions in both brain and spinal cord, and clarify further their pathology. The predictive value of such techniques for the development of clinical MS needs to be defined. METHODS: Brain and spinal MRI were performed on 60 patients after their first demyelinating event. A total of 50 patients were followed for 1 year, and 49 underwent repeat brain MRI 3 months after the initial scan. RESULTS: At baseline, 73% of patients had lesions on T2-weighted fast spin-echo (FSE) brain images and 42% had asymptomatic spinal cord lesions. Fast fluid-attenuated inversion-recovery brain did not improve detection of brain lesions. Repeat brain MRI demonstrated new FSE lesions in 43% of patients. After 1 year, 26% of patients developed MS. The MRI features that provided the best combination of sensitivity and specificity for the development of MS were the presence of new FSE lesions at follow-up and enhancing lesions at baseline. The frequency of developing clinical MS was higher for those with both brain and spinal cord lesions at baseline (48%) than brain lesions alone (18%). CONCLUSIONS: The combination of baseline MRI abnormalities and new lesions at follow-up, indicating dissemination in space and time, was associated with a high sensitivity and specificity for the early development of clinical MS. These data suggest a potential role for new diagnostic criteria for MS based on early MRI activity. Such criteria may be useful in selecting patients for therapeutic trials at this early clinical stage.

Adolescent↗

PubMed1991

Effects of prenatal exposure to benzodiazepine-related drugs on early development and adult social behaviour in Swiss mice--I. Agonists.

1. The present experiment examined, using a battery of tests, the effects of in utero exposure to the benzodiazepine agonists chlordiazepoxide and midazolam upon the early development and adult behaviour of offspring of Swiss mice. 2. Early development was generally retarded as a result of treatment. 3. Effects on adult social behaviour examined using the resident-intruder paradigm by determining the time spent in broad behavioural categories, showed marginal effects due to chlordiazepoxide and more striking actions due to midazolam treatments. Generally the treatments produced changes suggestive of an increase and a decrease in anxiety in males and females respectively.

Animals↗

PubMed1990

Histones in Xenopus laevis' early development: the race against time.

Using cloned histone gene variants, the expression of three types of histone gene clusters was studied at the RNA level during early development in Xenopus laevis. For each histone class the number of mRNA molecules per embryo strongly decreased upon ovulation and steadily increased during early development, with a slight decrease at the neurula stage. Variation of the stringency of hybridization revealed that none of the histone genes probed is specifically and uniquely expressed at any time point in embryogenesis. The observed variation of histone mRNA content with time after fertilization is consistent with what is known about rate constants for RNA synthesis and degradation and about histone mRNA storage in the oocyte, provided that approximately 11 h after fertilization a regulatory transition is proposed (KOSTER, DESTREE and WESTERHOFF (1988) J. Theor. Biol. 135, 139-167). Similarly, the observed amounts of histone mRNA could well be sufficient to direct the synthesis of the required amount of histone protein. Control Analysis reveals that late in development, the histone to DNA ratio is controlled virtually equally strongly by the rate constants of DNA replication, transcription and translation. The control coefficient for RNA degradation is only a little smaller, whereas that for proteolysis is negligible. Indeed, the deceleration of DNA synthesis around the Mid Blastula Transition (some 8 h after fertilization in our studies) is a regulatory step that is essential in order to allow Xenopus to synthesize sufficient histones to structure its DNA; otherwise the embryo would run out of histone protein and histone mRNA soon thereafter. A model that assumes that the lengthening of the cell cycle around the Mid Blastula Transition it itself a response to the decrease in the concentration of histone protein not complexed to DNA, is shown to account for the dynamics of histone and DNA synthesis during the first 50 h after fertilization.

Animals↗