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Temporal expression pattern of insulin-like growth factor mRNA during embryonic development in a teleost, rainbow trout (Onchorynchus mykiss).

The appearance of insulin-like growth factor I (IGFI) and II (IGF-II) mRNA was studied during rainbow trout embryonic development. Reverse transcription-polymerase chain reaction (RT-PCR), followed by Southern blotting and high-stringency hybridization with rainbow trout IGF-I and IGF-II cDNA probes, was used to detect all four forms of IGF-I mRNA and one form of IGF-II mRNA from whole-embryo total RNA isolated from a staged series. IGF-I and IGF-II mRNA were detected in unfertilized eggs. IGF-I and IGF-II mRNA were also detected during cleavage, gastrulation, and organogenesis, at hatching, during yolk absorption, and at feeding. IGF-IEa-1 and Ea-3 mRNA were detected in unfertilized eggs, while IGF-I Ea-4 was first detected at stage 9 when the zygotic genome is believed to become activated in rainbow trout. IGF-IEa-2 was not detected at any stage of embryonic development. IGF mRNA of immunoreactive peptides have been detected durin embryonic development in all vertebrates studied to date. Our results confirm the presence of IGF-I mRNA in teleost embryos. In addition, IGF-II mRNA is also present in teleost embryos. Our results suggest that the role IGF-I and IGF-II play during embryonic development may be conserved in vertebrates.

Animals↗

The effect of pentoxifylline on mouse in-vitro fertilization and early embryonic development.

This study was designed to assess the effect of pentoxifylline (PTX) on fertilization and early embryonic development in the mouse. Oocytes from superovulated B6CBA female mice were inseminated in vitro with spermatozoa from B6CBA males incubated with PTX according to different protocols, i.e. (i) 3.6 and 7.2 mM PTX washed out prior to insemination, (ii) 3.6 and 7.2 mM PTX diluted six times in the insemination medium and (iii) PTX present at 3.6 and 7.2 mM in the insemination medium. After insemination and washing, fertilization was assessed by the presence of 2-cell stage embryos. These were further cultured up to the blastocyst or egg-cylinder stage to assess embryonic development. Parthenogenetic activation was evaluated by exposing post-ovulatory oocytes to 3.6 and 7.2 mM PTX. If spermatozoa were washed free from PTX before insemination, no effect on either fertilization or subsequent development was found. If PTX was not washed out, fertilization was reduced significantly, yet development of fertilized oocytes was unaffected. If insemination was performed in the presence of PTX both fertilization and development were impaired. Parthenogenetic activation was not increased by PTX exposure. We conclude that if used in in-vitro fertilization, exposure of oocytes and/or zygotes to PTX has to be avoided by washing out the compound thoroughly to prevent adverse effects on early embryonic development.

Animals↗

The distribution of cells containing FMRFamide- and 5-HT-related molecules in the embryonic development of Viviparus ater (Mollusca, Gastropoda).

The timing and spatial distribution of cells containing FMRFamide- and 5-HT-related molecules in the embryonic development of the mollusc Viviparus ater are examined using immunohistochemistry. FMRFamide-like molecules emerge in the early stage E8 (8% of embryonic development) before the 5-HT immunoreactivity, and they are not only found during nervous system ontogeny. As the parts of the digestive tract differentiated, the pattern of the diffuse gut endocrine cells, present in adults, start to be established (E20-E30), and both open and closed cell types are immunoreactive to anti-FMRFamide antibody. From their appearance (E20), cells with a 5-HT-like phenotype are distributed in the central nervous ganglia and progressively assembled during embryonic development. The early occurrence of both these molecules in V. ater embryos reinforces the growing view that neurotransmitters play a regulatory role in embryogenic processes. In particular, the very early presence of FMRFamide-related factors suggests an involvement of these molecules in the regulation of basic, not only neuronal, cell behaviours, while 5-HT seems to be a more specific neural development signal.

Animals↗

HISTONE PROTEIN TRANSITION IN DROSOPHILA MELANOGASTER. II. CHANGES DURING EARLY EMBRYONIC DEVELOPMENT.

Employing cytochemical methods it was found that during the early embryonic development of Drosophila melanogaster the nuclei contain in sequence two kinds of chromosomal proteins. The cleavage nuclei (as also the pronuclei), until shortly before the blastoderm stage, contain an atypical (or juvenile) histone, stainable with bromophenol blue but not with alkaline fast green. The typical fast green-positive histone appears at the close of the period of the synchronized cleavage mitoses, just before blastulation, when nucleoli are first produced. The amount of DNA of the cleavage nuclei, as determined cytophotometrically, is nearly constant; therefore, the DNA moiety of the nucleohistone complex seems to remain unaffected by the protein shift during embryonic development. The implications of the protein shift in relation to the histone control of gene expression are discussed.

Animals↗

Quantitation of IGF-I, IGF-II, and multiple insulin receptor family member messenger RNAs during embryonic development in rainbow trout.

The IGF system has been shown to be important for normal embryonic growth in mice. Characterization of the IGF system in lower vertebrates is still in progress. To gain a greater understanding of the IGF system during embryonic development in teleosts, a competitive reverse transcription-polymerase chain reaction (RT-PCR) assay was developed and used to quantitate the levels of IGF-I and IGF-II mRNAs from rainbow trout embryos isolated from a staged series. The absolute number of molecules of IGF-I mRNA/microg total RNA was significantly lower than the absolute number of molecules of IGF-II mRNA/microg total RNA both during early and late embryonic development. The recent identification of multiple IGF type I receptor (rtIGFR) and insulin receptor (rtIR) cDNAs in rainbow trout has provided us with a tool to investigate the expression of these mRNAs. A relative quantitative RT-PCR assay was used to determine the steady state levels of two forms of rtIGFR and three forms of rtIR mRNAs in rainbow trout embryos. The relative levels of rtIGFR mRNAs were greater in embryos compared to adult tissues while the relative levels of rtIR mRNAs were generally lower. In a RT-PCR based assay, a differential ability to detect rtIGFR and rtIR mRNAs was shown, suggesting developmental regulation of polyadenylation. Our results suggest that IGF-II mRNA is the predominant IGF expressed in rainbow trout embryos. Our characterization of IGF ligand and receptor mRNA levels in rainbow trout embryos suggests that a functional IGF system exists during embryonic development in teleosts.

Animals↗

Composite interval mapping reveals a major locus influencing embryonic development rate in rainbow trout (Oncorhynchus mykiss).

Little is known about the genetics controlling the rate of embryonic development in salmonids, despite the fact that this trait plays an important role in the life history of wild and cultured stocks. We investigated the genetics of embryonic development rate by performing an analysis of quantitative trait loci (QTL) on two families of androgenetically derived doubled haploid rainbow trout produced from a hybrid of two clonal lines with divergent embryonic development rates. A total of 170 doubled haploid individuals were genotyped at 222 marker loci [219 amplified fragment length polymorphism (AFLP) markers, 2 microsatellites, and p53]. A genetic linkage analysis resulted in a map consisting of 27 linkage groups with 21 of the markers remaining unlinked at a minimum LOD of 3.0 and maximum theta of 0.40. Eight of these linkage groups were matched to published rainbow trout linkage groups. Composite interval mapping (CIM) revealed evidence for two QTL influencing time to hatch, and suggestive evidence for a third. These QTL accounted for a total of 24.6% of the variation in time to hatch. One of these QTL had a large effect on development rate, especially in one family of doubled haploids, in which it explained 25.6% of the variance in time to hatch. QTL influencing embryonic length and weight at the commencement of exogenous feeding were also identified. The QTL with the strongest effect on embryonic length (lenR13) mapped to the same position as the QTL with the strongest effect on time to hatch (tthR13), suggesting a single QTL may have a pleiotropic effect on both these traits. These results suggest that the use of clonal lines with a doubled haploid crossing design is an effective way of analyzing the genetic basis of complex traits in salmonids.

Animals↗

Alterations in titer and distribution of high mobility group proteins during embryonic development of Drosophila melanogaster.

High mobility group proteins are thought to have an architectural function in chromatin. Here we describe changes in titers, extent of phosphorylation, and cellular distribution of the three abundant HMG proteins during embryonic development of Drosophila. The titers of the HMG proteins HMGD, HMGZ, and D1 are highest in ovaries and at the beginning of embryonic development. They decrease continuously until cellularization of the embryo. Relative to the histone H1 titer, the levels of HMGD and D1 remain almost constant during gastrulation and organogenesis, whereas the titer of HMGZ increases during late organogenesis. Up to gastrulation, the development is accompanied by dephosphorylation of D1. In contrast, HMGD and HMGZ appear to be constitutively phosphorylated. As the high extent of phosphorylation of D1 is also characteristic in ovaries, it is likely that the posttranslational modifications of this protein observed in early embryonic stages are of maternal origin. Using site specific antibodies against helices I and III of HMGD and HMGZ and against the AT-hook motif of D1, protein-specific staining patterns have been observed during embryonic development. Despite high levels of HMG proteins at the beginning of embryonic development, we were unable to detect any of these proteins in nuclei of stage 2 embryos. The accumulation of the HMG proteins correlates with the onset of transcription in stage 3. Our results argue against a proposal of a shared role of HMGD and histone H1 in Drosophila chromatin.

Animals↗

The role of gonadotropin-releasing hormone in murine preimplantation embryonic development.

Previous studies have established the presence of an extrahypothalamic GnRH in a variety of tissues. GnRH receptor is known to be present in the placenta, which produces and secretes the decapeptide from the very early stages of placentation. We hypothesized that GnRH may play a role in the preimplantation development of embryos. To examine this hypothesis, we assessed GnRH and GnRH receptor messenger RNA (mRNA; RT-PCR) and protein expression (Immunohistochemistry) in preimplantation murine embryos at various developmental stages. Furthermore, preimplantation murine embryos were cultured with GnRH agonist and antagonist in vitro to assess the influence of GnRH analogs on embryo development. GnRH is expressed in the developing mouse embryo from morula to hatching blastocyst stages at the mRNA and protein levels. GnRH receptor mRNA is also present in the developing embryos studied. Preimplantation embryonic development was significantly enhanced by incubation with increasing concentrations of GnRH agonist and is significantly decreased by GnRH antagonist compared with that in the control group. Moreover, GnRH antagonist (5 and 10 microM) was able to completely block embryo development. The deleterious effect of GnRH antagonist on embryo development was reversed by increasing concentrations of the agonist, as determined by the number of embryos reaching the blastocyst stage.

Animals↗

Presence and possible role of c-ras and nuclear (c-fos and c-jun) proto-oncogene products in preimplantation embryonic development in mice.

The presence and possible role of products of nuclear (c-fos and c-jun) and c-ras proto-oncogenes were investigated in preimplantation embryonic development in mice. Polyclonal antibodies to c-fos or c-jun proto-oncogene products did not affect development of in vitro-cultured embryos from two-cell to morula or from morula to late blastocyst stages. However, v-H-ras monoclonal antibody (mAb) to c-ras protein (p21), although it did not inhibit the development of in vitro-cultured embryos from two-cell to morula stages, it significantly (P < .001-.005) inhibited the development of morula to late blastocyst stages in a dose-dependent manner. The effects of v-H-ras mAb were specific, since immunoabsorption with synthetic ras peptide completely blocked inhibitory effects of v-H-ras mAb. Neither c-fos nor c-jun antibodies reacted with specific proteins corresponding to c-fos (62 kDa) and c-jun (39 kDa) products on the Western blots of various murine ova/embryos extracts. However, the c-fos and c-jun antibodies reacted with 62 and 39 kDa protein bands, respectively, on the blot of NIH 3T3 cells extract. The v-H-ras mAb specifically identified 21 +/- 3 kDa protein corresponding to c-ras p21 on the blots of early as well as late blastocyst extracts. The rat control ascites IgG1 did not react with any protein band on the blots of various ova/embryo extracts. The reactions of v-H-ras mAb on the Western blots of blastocyst extracts were specific, since immunoabsorbed antibody was unable to react with any specific band on blots of early or late blastocyst extract. These results were further confirmed by immunoprecipitation procedure utilizing v-H-ras mAb. Again, the v-H-ras mAb immunoprecipitated a 21 kDa band from early as well as late blastocyst extracts. The rat control ascites IgG1 did not react with any band corresponding to p21 in the immunoprecipitation procedure. These results suggest that the specific products of nuclear proto-oncogenes, the c-fos and c-jun, are not detected in murine ova and preimplantation embryos, and the respective antibodies do not inhibit embryogenesis, indicating that they may not play a major role in early embryonic development. On the other hand, the product of c-ras proto-oncogene is specifically expressed in the blastocyst-stage embryos and may have a possible role in preimplantation embryonic development in mice.

3T3 Cells↗

[Effect of zuoguiwan on early embryonic development of mice].

Effects of Zuoguiwan (ZGW, a prescription for reinforcing Kidney Yin) on early embryonic development were observed by using embryonic developmental retardation model of mice formed by alcohol. Drug was given in three ways: add ZGW into cultural medium directly (group A), add the serum of mice received ZGW (group B) and cultured the embryo taken from ZGW treated mice (group C). The result was compared with that treated with Bazhen decoction (BZD, a prescription for supplementing Qi and blood). Results showed that the in vitro developmental rate of embryo from 2-cell stage to blastula stage in group B and C, which approached to normal control group, was higher than that in untreated model obviously. While in BZW group, it was higher than in normal control group only in certain stage. However, adding ZGW directly into culture medium didn't reveal marked effect on early embryonic development.

Animals↗

Comparison of various maturation treatments on in vitro maturation of goat oocytes and their early embryonic development and cell numbers.

In the present study, comparison of 2 different culture media (Ham's F-12 and M-199) for supporting in vitro maturation of goat oocytes, and their subsequent embryonic development was evaluated in the presence or absence of sera (estrous goat serum, EGS and fetal calf serum, FCS) and hormones (FSH, 0.5 ug/ml, LH, 5 ug/ml and estradiol, 1 ug/ml). Neither medium (Ham's F-12 or M-199) when supplemented with EGS and hormones showed any notable changes in the maturation rate nor in cleavage and blastocyst development. The mean cell number for blastocysts was also significantly low (P < 0.05). However, Ham's F-12 medium supplemented with FCS and hormones showed a considerable increase in the maturation rate, but subsequent embryonic development was not appreciably increased. However, maturation, cleavage and blastocyst development rates of oocytes matured in M-199 medium in combination with 10% FCS and hormones were significantly higher (P < 0.05). Mean cell number per blastocyst was also significantly increased in this latter treatment compared with that of the other groups (P < 0.05). The results thus indicated that both the culture medium and serum have a marked effect on maturation and subsequent embryonic development. Further, the results also showed that the combination of M-199 with FSH, LH and E2 supplemented with 10% FCS was the most efficacious medium for in vitro maturation and subsequent embryonic development of the media, sera and hormone combinations studied.

Journal Article↗

Effects of dithiothreitol and boar on pronuclear formation and embryonic development following intracytoplasmic sperm injection in pigs.

The objective of this study was to improve normal fertilization, male pronuclear formation and embryonic development following intracytoplasmic injection of dithiothreitol (DTT)-treated boar spermatozoa. To determine the effect of DTT treatment, frozen-thawed boar spermatozoa were treated with DTT for 0, 10, 30, and 60 min, and injected into porcine oocytes. The effects of DTT and male difference on normal fertilization and embryonic development were investigated. The mean normal fertilization rate in the groups treated with DTT for 30 min (73.8%) and 60 min (74.9%) was higher (P < 0.05) than that in the control group (49.3%). The mean blastocyst formation rate in the group treated with DTT for 30 min (23.2%) was higher (P < 0.05) than that in the other groups (8.7-10.9%). Among boars there was no difference in normal fertilization, but there was a significant difference between the non-treated and the DTT-treated groups. The mean rate of blastocyst formation was different (P < 0.05) among boars, and between the non-treated and DTT-treated groups. The mean number of cells in blastocysts was similar among the boars and between the non-treated and the DTT-treated groups. In conclusion, DTT treatment for 30 min increased the rate of normal fertilization and embryonic development to the blastocyst stage. Furthermore, the rate of blastocyst formation of oocytes injected with spermatozoa differed among boars.

Analysis of Variance↗

Antibodies to sperm surface antigens and the c-myc proto-oncogene product inhibit early embryonic development in mice.

The effects of antibodies against sperm antigens and the c-myc proto-oncogene product on early embryonic development were investigated in mice. Affinity-purified Fab' antibodies against lithium diiodosalicylate (LIS)-solubilized murine sperm extract and fertilization antigen (FA-1) reduced (p less than 0.01 to p less than 0.001) blastulation rates of in vitro cultured 2-cell murine embryos primarily because of an arrest of development at the morula stage. Similarly, the c-myc monoclonal antibody (mAb) affected early embryonic development in a dose-dependent manner. These effects were specific, since immunoabsorption, with its respective peptide, completely blocked the inhibitory effect of the c-myc mAb. Anti-LIS sperm Fab' identified four protein bands (approx. 36, 29, 24.6, and 17.6 kDa) on Western blots of extracts from unfertilized and fertilized ova, one band (approx. 68 kDa) each on 4-8-cell embryo and morula extracts, and one band (approx. 53 kDa) on blastocyst extracts. Anti-FA-1 Fab' did not react with unfertilized or fertilized ova, but specifically identified two protein bands (approx. 53 and 25.7 kDa) on blots of 2-cell-embryo extract, one band (approx. 25.7 kDa) on morula extract, and one band (approx. 53 kDa) on blastocyst extract. The c-myc mAb did not react with any band corresponding to the c-myc protein on blots of extracts from unfertilized or fertilized ova, 2-cell embryos, 4-8-cell embryos, morulae, or blastocysts. These results suggest that some of the cross-reacting sperm antigens that are expressed during early cleavages, and the product of the c-myc proto-oncogene may have a role in normal early embryonic development.

Animals↗

Genome-wide expression dynamics during mouse embryonic development reveal similarities to Drosophila development.

Gene transcription mediates many vital aspects of mammalian embryonic development. A comprehensive characterization and analysis of the dynamics of gene transcription in the embryo is therefore likely to provide significant insights into the basic mechanisms of this process. We used microarrays to map transcription in the mouse embryo in the important period from embryonic day 8 (e8.0) to postnatal day 1 (p1) during which the bulk of the differentiation and development of organ systems takes place. Analysis of these expression profiles revealed distinct patterns of gene expression which correlate with the differentiation of organs including the nervous system, liver, skin, lungs, and digestive system, among others. Statistical analysis of the data based on Gene Ontology (GO) group annotation showed that specific temporal sequence patterns in gene class utilization across development are very similar to patterns seen during the embryonic development of Drosophila, suggesting conservation of the temporal progression of these processes across 550 million years of evolution. The temporal profiles of gene expression and activation of processes revealed here provide intriguing insights into the mechanisms of mammalian development, embryogenesis, and organogenesis, as well as into the evolution of developmental processes.

Animals↗

The effects of in ovo rhIGF-I administration on expression of the growth hormone secretagogue receptor (GHSR) during chicken embryonic development.

Growth hormone secretion is under the control of a pair of hypothalamic factors, growth hormone releasing hormone and somatostatin. The growth hormone secretagogue receptor (GHSR) and its endogenous ligand represent a novel third method regulating the release of growth hormone. Early chicken embryonic development has been proposed to be independent of GH. However, recent evidence shows that peripheral GH secretion has paracrine/autocrine functions during embryonic development. In the current study, we used the reverse-transcriptase polymerase chain reaction to determine the expression pattern of the GHSR during embryonic development and the effects of in ovo recombinant human (rh) IGF-I administration on its expression pattern. Eggs were injected once with 100 ng rhIGF-I in 10 mM acetic acid, and 0.1% BSA per embryo on embryonic day 3. Total RNA was isolated from whole embryos on embryonic day (E) 0-6 (n=6 per day), thoracic/abdominal halves of the embryos on E7- E8 (n= 6 per day) and Pectoralis muscle on E9-E20 (n= 4 per day). We found that GHSR expression was low during E0-E4, followed by an increase on E5 and remained constant through E17. GHSR expression then increased on E18 before reducing on E20. A similar pattern was found in the rhIGF-I treated embryos with the exception of a significant increase in GHSR expression on E8. These data indicate that the GHSR may be active in regulating GH secretion during early embryonic development, and upregulation of the GHSR gene following IGF-I administration may have an important role in the determination of postnatal muscle growth.

Animals↗

Subcellular translocation signals regulate Geminin activity during embryonic development.

BACKGROUND INFORMATION: Geminin (Gem) is a protein with roles in regulating both the fidelity of DNA replication and cell fate during embryonic development. The distribution of Gem is predominantly nuclear in cells undergoing the cell cycle. Previous studies have demonstrated that Gem performs multiple activities in the nucleus and that regulation of Gem activation requires nuclear import in at least one context. In the present study, we defined structural and mechanistic features underlying subcellular localization of Gem and tested whether regulation of the subcellular localization of Gem has an impact on its activity in cell fate specification during embryonic development. RESULTS: We determined that nuclear localization of Gem is dependent on a bipartite NLS (nuclear localization signal) in the N-terminus of Xenopus Gem protein. This bipartite motif mapped to a Gem N-terminal region previously shown to regulate neural cell fate acquisition. Microinjection into Xenopus embryos demonstrated that import-deficient Gem was incapable of modulating ectodermal cell fate, but that this activity was rescued by fusion to a heterologous NLS. Cross-species comparison of Gem protein sequences revealed that the Xenopus bipartite signal is conserved in many non-mammalian vertebrates, but not in mammalian species assessed. Instead, we found that human Gem employs an alternative N-terminal motif to regulate the protein's nuclear localization. Finally, we found that additional mechanisms contributed to regulating the subcellular localization of Gem. These included a link to Crm1-dependent nuclear export and the observation that Cdt1, a protein in the pre-replication complex, could also mediate nuclear import of Gem. CONCLUSIONS: We have defined new structural and regulatory features of Gem, and showed that the activity of Gem in regulating cell fate, in addition to its cell-cycle-regulatory activity, requires control of its subcellular localization. Our data suggest that rather than being constitutively nuclear, Gem may undergo nucleocytoplasmic shuttling through several mechanisms involving distinct protein motifs. The use of multiple mechanisms for modulating Gem subcellular localization is congruent with observations that Gem levels and activity must be stringently controlled during cell-cycle progression and embryonic development.

Active Transport, Cell Nucleus↗

Embryonic development of the Pacific lamprey, Entosphenus tridentatus.

Embryonic development of the Pacific lamprey, Entosphenus tridentatus, from Japan is described. Egg sizes averaged 1.249 mm (longest axis) and 1.145 mm (shortest axis), the time required for hatching being 11 days at 18 degrees C, shorter than previously reported for a lower water temperature (19 days at 15 degrees C). Early development in E. tridentatus proceeded at a similar rate to that in other lampreys, in spite of different rearing water temperatures for the latter, indicating possible specific differences in basic developmental rates.

Animals↗

Exposure to zinc oxide nanoparticles inhibits preimplantation embryonic development by disrupting zygotic genome activation.

The potential adverse effects of zinc oxide nanoparticles (ZnONPs) on human reproductive health may arise from their increasing industrial and commercial applications. However, their effects on preimplantation embryonic development and the related molecular mechanisms are still not well understood. Here, we demonstrate that ZnONPs exposure exhibit toxicity to a critical developmental period in mice. We observed that sustained exposure to ZnONPs in vitro resulted in embryonic development arrest at the 2-cell stage. To identify the susceptible stage, we controlled experiments to treat embryos with ZnONPs in the different processes of early embryonic development and determined that ZnONPs mainly to affect 2-cell stage embryos. According to the RNA-seq and EU (5-ethynyl uridine) analysis, the transcriptional activity of minor ZGA genes increased in the late 2-cell embryos following ZnONPs exposure. Subsequently, we employed multi-omics assays, including CUT&Tag and ATAC-seq. We found that ZnONPs exposure led to increased enrichment of H3K27ac (Histone H3 acetylated lysine 27) in late 2-cell embryos and enhanced chromatin accessibility, which led to abnormal upregulation of minor zygotic genome activation (ZGA) genes. In addition, the direct occupancy of ZnONPs at H3K27ac modification sites was verified through pulldown and immunoprecipitation. In conclusion, our findings demonstrate that ZnONPs exposure disrupting minor ZGA by interfering with H3K27ac erasure on the embryonic genome and ultimately impairing the developmental potential of embryos.

Animals↗