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At least 271 records · Page 15Linked to original sources

PubMed1997

Expression of apo-aequorin during embryonic development; how much is needed for calcium imaging?

Aequorin is a bioluminescent calcium indicator consisting of a 21 kDa protein (apo-aequorin) that is covalently linked to a lipophilic cofactor (coelenterazine). The aequorin gene can be expressed in a variety of cell lines and tissues, allowing non-invasive calcium imaging of specific cell types. In the present paper, we describe the possibilities and limitations of calcium imaging with genetically introduced apo-aequorin during embryonic development. By injecting aequorin into sea urchin, Drosophila and zebrafish eggs, we found that higher aequorin concentrations are needed in smaller eggs. Our results suggest that for measuring resting levels of free cytosolic calcium, one needs aequorin concentrations of at least 40 microM in sea urchin eggs, 2 microM in Drosophila eggs, and only 0.11 microM in zebrafish eggs. A simple assay was used to determine the absolute concentrations of expressed apo-aequorin and the percentage of aequorin formation in vivo. The use of this assay is illustrated by expression of the aequorin gene in Drosophila oocytes. These oocytes form up to 1 microM apo-aequorin. In our hands, only 0.3% of this apo-aequorin combined with coelenterazine entering from the medium to form aequorin, which was not enough for calcium imaging of the oocytes, but did allow in vivo imaging of the ovaries. From these studies, we conclude that coelenterazine entry into the cell is the rate limiting step in aequorin formation. Based on the rate of coelenterazine uptake in Drosophila, we estimate that complete conversion of 1 microM apo-aequorin would take 50 days in zebrafish eggs, 2 days [corrected] in Drosophila eggs, 7 days in sea urchin eggs or 18 h in a 10 microm tissue culture cell. Our results suggest that work based on genetically introduced apo-aequorin will be most successful when large amounts of small cells can be incubated in coelenterazine. During embryonic development this would involve introducing coelenterazine into the circulatory system of late stage embryos. Calcium imaging in early stage embryos may be best done by injecting aequorin, which circumvents the slow process of coelenterazine entry.

Aequorin↗

PubMed1986

Does estradiol play a role in ovarian maturation or embryonic development of the silkworm?

Since estradiol has been detected in Bombyx ovaries effects of estradiol and other steroids on the growth and maturation of the silkworm ovary, rate of oviposition, and embryonic development were examined as a part of a study aimed at the clarification of physiological significance of estradiol in insects. These steroids were injected at various doses into the whole pupae and into the isolated pupal abdomens. No significant effect by the injections was observed on the ovarian development, as judged by increase in protein content or wet weight of ovaries and pattern of protein constituents including vitellin. However, rate of oviposition was considerably affected by the injection of estradiol at high doses. No clear effect was observed on embryonic development or determination of diapause by the injection of estradiol into the pupae. Effects of injection of anti-estrogen, nafoxidine, into the isolated abdomens and whole pupae were also examined. No effects were observed on ovarian development by injection. The relationship between physiological significance of the vertebrate steroids and metabolic activity of the ovary is discussed.

Animals↗

PubMed2006

Investigation of direct toxic and teratogenic effects of anticoagulants on rat embryonic development using in vitro culture method and genotoxicity assay.

Heparin and low molecular weight heparins (LMWHs) are used to reduce the incidence of venous thromboembolism in pregnancy. Although, these agents have been shown to be safe when used during pregnancy, the studies about direct toxic and teratogenic effects of these drugs on embryonic development are limited. In this study, the effects of heparin and LMWHs on rat embryonic development were investigated by using in vitro embryo culture and micronucleus (MN) assay methods. Rat embryos were cultured in vitro in the presence of different concentrations of heparin (5-40 IU/ml), dalteparin (2.5-20 IU/ml), enoxaparin (25-100 microg/ml) and nadroparin (1-4 IU/ml). Effects of anticoagulants on embryonic developmental parameters were compared and embryos were evaluated for the presence of any malformations. After culturing the embryos, classic MN assay was performed. Anticoagulants significantly decreased all growth and developmental parameters dose-dependently. Dalteparin and enoxaparin were found to cause more developmental toxicity than heparin and nadroparin. Along with haematoma in general, heparin and nadroparin caused maxillary deformity, situs inversus and oedema most frequently, while neural tube defects were observed with dalteparin and enoxaparin. All agents also significantly induced MN formation in rat embryonic blood cells. These results indicate the possible genotoxic effects of anticoagulant agents on the developing rat embryo when applied directly.

Abnormalities, Drug-Induced↗

PubMed1991

Plasma patterns of prolactin, progesterone, and estradiol during early pregnancy in aging rats: relation to embryonic development.

Regularly cyclic, middle-aged female rats exhibit a decreased incidence of fertility, and those females that are fertile produce smaller litters. This decreased litter size is directly related to a reduced number of normal blastocysts available for implantation. Recent evidence indicates that embryonic abnormalities in middle-aged rats become apparent as early as Day 2 of pregnancy. Inasmuch as the semicircadian secretion of prolactin (PRL) is essential for the rescue of corpora lutea during early gestation and luteal production of progesterone (P) and estradiol (E2) in sufficient quantities is obligatory for embryonic development and implantation, the present study examined the profiles of plasma PRL, P, and E2 during the first 3 days of pregnancy in both young and middle-aged rats and assessed the embryonic development in these same animals. Regularly cyclic, middle-aged (9-11 mo) and young (4-5 mo) rats were cannulated via the right jugular vein on Diestrus Day 2 and mated with fertile males on proestrus. The next morning, sperm in the vaginal lavage confirmed mating, and that day was designated Day 1 of pregnancy. Beginning at 1400 h on Day 1 and continuing to 2400 h on Day 2, serial blood samples were taken at 2-h intervals for PRL assay. In the first experiment, samples were also collected at 8-h intervals during Days 1-3 for measurement of plasma P.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed2001

Embryonic development of the central projection of auditory afferents (Schistocerca gregaria, Orthoptera, Insecta).

The auditory system of Schistocerca gregaria is a well investigated sensory network in the adult grasshopper. Here we present a first study on the embryonic development of this neuronal network. Focussing on the auditory receptor cells we show that they differentiate axonal processes at around 45% of embryonic development. These axons fasciculate with the intersegmental nerve and enter the central nervous system by 45-50% of development. First collaterals sprout into the major arborization area, the frontal auditory projection area of the metathoracic ganglion by 60%. This projection increases in density until an adult-like morphology is established by 90% of development. Furthermore, by the end of embryogenesis all three types of receptor fiber projections can be distinguished. This development is independent of a hearing ability, which develops much later during postembryonic life. The auditory projection co-develops with the fusion of neuromeres to the metathoracic ganglion, the formation of the target neuropile areas and the expression of the synapse associated molecule synapsin. Fasciclin I and Lachesin, both potential axon-guidance molecules, are expressed strongly on both, peripheral and central auditory pathways and, although much weaker, within the synaptic target area.

Animals↗

PubMed1976

Galactosyltransferase activities during embryonic development of chick neural tissue.

Galactosyltransferase specific activities in embryonic chick retina, optic tectum, and telencephalon were found to decline during embryonic development. Incorporation of galactose from nucleotide sugar into exogenously added glycoprotein acceptor was measured in the presence of excess of glycoprotein acceptor. This ensured that the specific activity measurements were reflections of tru enzyme specific activity rather than availability of acceptor. Moreover, we have shown that the decline in specific activity is not due to degradation of the nucleotide sugar, UDP-galactose, under our in vitro assay conditions. Enzymatic specific activity declined sharply with embryonic age for all tissues tested. This decline was not affected by the presence of 5-bromodeoxyuridine during in vitro culture of embryonic chick neural retina above that caused by the culturing alone. Galactosyltransferase activity was not found to be associated with the plasma membrane fraction from homogenized tissue but rather with the microsomal fraction. Thus, the changes in galactosyltransferase specific activity detected here do not reflect changes at the cell surface.

Animals↗

PubMedDate not supplied

[Geomagnetic activity and human embryonic development].

A retrospective analysis of weekly values of geomagnetic activity during embryonal development for healthy and mentally diseased people was performed. A statistically significant in the aa-index for mentally diseased people by 4.5-5.5 week of embryonic growth was revealed. This suggesting that the level of geomagnetic activity affects the laying and development of the central nervous system.

Earth, Planet↗

PubMed1999

Apolipoprotein B-related gene expression and ultrastructural characteristics of lipoprotein secretion in mouse yolk sac during embryonic development.

In mice, the yolk sac appears to play a crucial role in nourishing the developing embryo, especially during embryonic days (E) 7;-10. Lipoprotein synthesis and secretion may be essential for this function: embryos lacking apolipoprotein (apo) B or microsomal triglyceride transfer protein (MTP), both of which participate in the assembly of triglyceride-rich lipoproteins, are apparently defective in their ability to export lipoproteins from yolk sac endoderm cells and die during mid-gestation. We therefore analyzed the embryonic expression of apoB, MTP, and alpha-tocopherol transfer protein (alpha-TTP), which have been associated with the assembly and secretion of apoB-containing lipoproteins in the adult liver, at different developmental time points. MTP expression or activity was found in the yolk sac and fetal liver, and low levels of activity were detected in E18.5 placentas. alpha-TTP mRNA and protein were detectable in the fetal liver, but not in the yolk sac or placenta. Ultrastructural analysis of yolk sac visceral endoderm cells demonstrated nascent VLDL within the luminal spaces of the rough endoplasmic reticulum and Golgi apparatus at E7.5 and E8.5. The particles were reduced in diameter at E13.5 and reduced in number at E18.5;-19. The data support the hypothesis that the yolk sac plays a vital role in providing lipids and lipid-soluble nutrients to embryos during the early phases (E7;-10) of mouse development. secretion in mouse yolk sac during embryonic development.

Animals↗

PubMed1996

The importance of cytoplasm in early embryonic development.

PURPOSE: A mouse model was used to evaluate the consequences of partial cytoplasm removal, which mimics the consequence of human early embryo fragmentation, at the one-cell stage on embryonic development to the morula and blastocyst stages. RESULTS: Opening the zona pellucida at the zygote stage has no detrimental effect on the number of differentiated or total cells at morula/blastocyst stage. However, reduced cytoplasm significantly affects the number of inner cell mass cells, 21.7 (10% cytoplasm removed) vs 27.6 (control) and 15.1 (20% cytoplasm removed) vs 24.7 (control). CONCLUSIONS: The contribution of cytoplasm of maternal origin is critical to early embryonic development.

Animals↗

PubMed2006

Alterations in hepatic metabolism of adult male rats following exposure to hydroxyprogesterone during embryonic development.

AIM: To investigate the effect of in utero exposure to hydroxyprogesterone (HP) on liver metabolism in adult male albino rats. METHODS: Pregnant Wistar strain albino rats were exposed to supra-normal levels (10 mg/kg and 25 mg/kg) of HP on days 1, 7 and 14 of pregnancy. The male pups were maintained under controlled conditions and the rats were killed 90 days after birth. The liver tissue was immediately excised, weighed and used for biochemical assays. RESULTS: The activity levels of succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), glucose-6-phosphate dehydrogenase (G-6-PDH), malate dehydrogenase (MDH) and aminotransaminases were significantly increased in the livers of rats exposed to HP during embryonic development. The lactate dehydrogenase (LDH) activity level was significantly decreased in the liver of experimental rats. Furthermore, there was a significant elevation of activity levels of antioxidant enzymes (glutathione S-transferase [GST] and catalase [CAT]) with an increased lipid peroxidation in the hepatic tissue of experimental rats compared with the control group. CONCLUSION: The results of the present study suggest that there is an increase in the oxidative metabolism, antioxidative mechanism and levels of lipid peroxidation in rats exposed to HP during embryonic development. The increased aminotransaminase activities in these rats reveal tissue damage and disruption of mitochondrial integrity.

17-alpha-Hydroxyprogesterone↗

PubMed2004

Differential toxicity of copper, zinc, and lead during the embryonic development of Chasmagnathus granulatus (Brachyura, Varunidae).

Ovigerous females of the estuarine crab Chasmagnathus granulatus were exposed to copper (0.01 and 1 mg/L), zinc (0.05, 1, and 10 mg/L), or lead (0.01 and 1 mg/L) during early, late, or whole embryonic development. None of the assayed heavy metals produced a significant mortality of females, neither a decrease in the number of hatched larvae nor a decrease in the egg incubation time, but several morphological abnormalities were detected in hatched larvae. The abnormalities were classified in three categories: eye, body pigmentary, and body morphological abnormalities. Those larvae with eye and body pigmentary abnormalities, particularly those involving retinal pigments and chromatophores, showed the highest incidence by exposure to the assayed metals. In addition, embryos were more susceptible to copper and zinc during the late period of development, whereas the effect of lead was greater during the early period of embryogenesis. Some teratogenic effects observed in C. granulatus embryos exposed to heavy metals, particularly the hypertrophy and hypopigmentation of eyes observed in the laboratory at a lead concentration as low as that reported for the natural environment, could be considered as sensitive biomarkers for this kind of pollutant.

Animals↗

PubMed2006

Kinetics of energy source utilization in Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) embryonic development.

The present work evaluates the kinetics of utilization of the main potential energy sources throughout the embryonic developmental stages of Boophilus microplus. The embryonic development of this arthropod is completed in 21 days. Cellularization of the blastoderm occurs on the 6th day and is rapidly followed by germ band extension and segmentation, whose first signs are visible on the 7th day. Cellularization is typically a maternal-driven process, carried out by molecular determinants deposited in the oocyte during oogenesis. On the other hand, segmentation is of zygotic nature, being the consequence of the synthesis of various components by the growing embryo. The enhancement in total B. microplus RNA was observed after cellularization, corroborating the replacement of maternal-driven processes by embryonic zygotic expression. An abrupt increase in oxygen consumption was observed from cellularization until the 8th day of development. The reduction in dry weight at the same period and the susceptibility of oxygen consumption to KCN suggest that the respiration process is activated during early embryonic development. A marked decrease in total lipid content occurred between the 5th and 7th days of development, suggesting this is the main energy source for cellularization. A major reduction in carbohydrate content occurred later, between the 7th and 9th days, and it could be assigned to the morphological segmentation of the embryo. Although the total amount of proteins remains unchanged from oviposition to hatching, a 15% reduction in vitellin (VT) content was observed before cellularization, up to the 4th day after egglaying. This observation was correlated to the synthesis of new proteins needed to support early embryo development. Additional 20% of VT was consumed thereafter, mainly at the end of embryogenesis, and in this case VT is probably used as energy source to the older embryo. Altogether, these data indicate different energy sources for maternal and zygotic driven processes.

Animals↗

PubMed2000

Human oviductal gonadotropin-releasing hormone: possible implications in fertilization, early embryonic development, and implantation.

The oviduct is host to gametes and early embryos at a critical point in their lives. It is clear that the interactions of gametes/early embryo with the maternal oviduct in an autocrine and paracrine manner provide a microenvironment that enhances fertilization, early embryonic development, and implantation. Moreover, there is considerable evidence that an extrahypothalamic GnRH may play a substantial role as a molecular autocrine/paracrine regulator in these events. Gametes and preimplantation embryos express GnRH and GnRH receptor at both messenger ribonucleic acid (mRNA) and protein levels. However, whether GnRH is produced by the human oviduct has not yet been demonstrated. We used RT-PCR and immunohistochemical techniques to investigate GnRH mRNA and protein expression in human fallopian tubes throughout the menstrual cycle of premenopausal fertile patients. Our results, at both the mRNA and protein levels, revealed cycle-dependent production of an oviductal GnRH with expression during the luteal phase. Moreover, GnRH immunostaining was localized in the tubal epithelium during the luteal phase. On the basis of these data, we suggest that during reproductive life, oviductal GnRH may play a substantial paracrine/autocrine role in human fertilization, early embryonic development, and implantation.

Adult↗

PubMedDate not supplied

Effects of cyproheptadine on the rat yolk sac membrane and embryonic development in vitro.

Electron-microscopic examinations of rat embryonic yolk sacs treated in vitro with 1.5 X 10(-5) M cyproheptadine showed proliferation of the lysosomal structures; other organelles remained unaffected, and also overall yolk-sac growth and vascularization were comparable to non-treated samples. Radioactive measurements with 125I-labelled albumin showed that yolk sacs and embryos of the cyproheptadine-treated group incorporated less radioactivity than the controls. Embryos inside the yolk sacs, treated either for 24 or 48 h, were severely retarded in growth and differentiation (approximately 50% of the controls). It is suggested that the specific action of cyproheptadine on yolk-sac lysosomal structures, combined with reduced macromolecular transport, is the cause of inhibited embryonic development.

Animals↗

PubMed1983

Glycoprotein synthesis and embryonic development.

One of the most striking morphogenetic events during embryonic development is gastrulation, a process that leads to formation of the primitive gut. Using sea urchin embryos, we have studied the synthesis and function of glycoproteins during gastrulation. These studies have revealed that at least three processes are induced prior to gastrulation: de novo synthesis of dolichol; phosphorylation of dolichol by dolichol kinase, which may catalyze the final step in the de novo pathway; and initiation of the synthesis of N-linked glycoproteins. Whether or not activation of the glycosylation process results merely because of the production of dolichyl monophosphate or because, in addition, proteins containing glycosylatable-Asn-X-Ser/Thr-sequences are first translated just prior to gastrulation, is currently being investigated.

Animals↗

PubMed1996

Transfer of IgA from albumen into the yolk sac during embryonic development in the chicken.

In the chicken, maternal antibodies are transferred into the egg and subsequently transported into the developing embryo. IgG is the primary immunoglobulin isotype of the egg yolk, while IgM and IgA are mainly found in the albumen. However, considerable amounts of IgM and IgA of unknown origin are found one day prior to hatching in the yolk sac. These antibodies are not synthesized de novo by the embryo proper, thus pointing to a transfer from the albumen into the egg yolk during development. To further address this question, 125I labelled chicken IgA was injected into the albumen of freshly laid eggs. On day 21 of embryonic development, 125I-IgA was found in the yolk sac content. On average (n = 6) 36.2 +/- 7.2% of the injected radioactivity was recovered from this compartment and shown to be associated with IgA. Comparison of total IgA in the albumen of freshly laid eggs with the amounts of IgA in yolk sac content showed similar results with a 44% transfer rate. An increase of the IgA concentration in the yolk sac was first detectable between days 14 and 16 of embryonic development. These data clearly show that IgA is transferred from the albumen into the yolk sac, most likely by a transport across the yolk sac membrane.

Animals↗

PubMed2002

Arginase expression in mouse embryonic development.

We are using the model of the developing mouse embryo to elucidate the pattern of arginase expression in mammalian cells in normal animals and in arginase I (AI) deficiency during development by digoxigenin-labeled RNA in situ hybridization. Our goal is to understand the regulation of these isozymes, with the expectation that this knowledge will help patients suffering from AI deficiency. We found that AI mRNA was widely and strongly expressed in the normal developing mouse embryo; in contrast, a relatively strong AII mRNA signal was found only in the intestine. In the AI knockout mouse embryo, no AII overexpression was found. These results indicated that arginases are needed in mouse embryonic development and AI is the principal form required. The strong AI expression in the peripheral nervous system suggests that the pathogenesis of the neurological retardation in AI deficiency may be conditioned by AI deficiency in the nervous system during embryonic development.

Animals↗

PubMed2001

In vitro growth, maturation, fertilization, and embryonic development of oocytes from porcine preantral follicles.

This study was conducted to identify an in vitro culture system that would support intact porcine follicle growth from preantral follicle to antral stages, oocyte maturation, fertilization, and embryonic development; and to evaluate factors that influence porcine preantral follicle growth in vitro. Preantral follicles isolated from prepubertal porcine ovaries were cultured for 4 days in the presence of different concentrations of porcine serum and FSH, and with different numbers of follicles per well. A series of experiments showed that porcine antral follicles can be grown at a high frequency in vitro from healthy preantral follicles with intact theca when cultured in North Carolina State University 23 medium supplemented with 1.5 ng/ml FSH, 7.5% serum, and when cultured with three follicles per well. After 4 days of culture, 68% healthy cumulus-enclosed oocytes from these follicles were obtained, and 51% of the oocytes completed meiotic maturation to the metaphase II stage. Fifty-three percent of the mature oocytes underwent fertilization, 43% of the fertilized oocytes cleaved, and 13% developed to the blastocyst stage. The results show 1) that porcine preantral follicles can grow efficiently to the antral stage using these culture conditions, and 2) that oocytes from in vitro-matured porcine preantral follicles can acquire meiotic competence and undergo fertilization and embryonic development.

Animals↗