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Embryonic Viability (embryonic + viability)
Selected AbstractsMice with mutations in Mahogunin ring finger-1 (Mgrn1) exhibit abnormal patterning of the left,right axisDEVELOPMENTAL DYNAMICS, Issue 12 2006Christina D. Cota Abstract Mahogunin Ring Finger 1 (Mgrn1) encodes a RING-containing protein with ubiquitin ligase activity that has been implicated in pigment-type switching. In addition to having dark fur, mice lacking MGRN1 develop adult-onset spongy degeneration of the central nervous system and have reduced embryonic viability. Observation of complete situs inversus in a small proportion of adult Mgrn1 mutant mice suggested that embryonic lethality resulted from congenital heart defects due to defective establishment and/or maintenance of the left,right (LR) axis. Here we report that Mgrn1 is expressed in a pattern consistent with a role in LR patterning during early development and that many Mgrn1 mutant embryos show abnormal expression of asymmetrically expressed genes involved in LR patterning. A range of complex heart defects was observed in 20,25% of mid-to-late gestation Mgrn1 mutant embryos and another 20% were dead. This finding was consistent with 46,60% mortality of mutants by weaning age. Our results indicate that Mgrn1 acts early in the LR signaling cascade and is likely to provide new insight into this developmental process as Nodal expression was uncoupled from expression of other Nodal-responsive genes in Mgrn1 mutant embryos. Our work identifies a novel role for MGRN1 in embryonic patterning and suggests that the ubiquitination of MGRN1 target genes is essential for the proper establishment and/or maintenance of the LR axis. Developmental Dynamics 235:3438,3447, 2006. © 2006 Wiley-Liss, Inc. [source] EVOLUTION UNDER RELAXED SEXUAL CONFLICT IN THE BULB MITE RHIZOGLYPHUS ROBINIEVOLUTION, Issue 9 2006Magdalena Tilszer Abstract The experimental evolution under different levels of sexual conflict have been used to demonstrate antagonistic coevolution in muscids, but among other taxa a similar approach has not been employed. Here, we describe the results of 37 generations of evolution under either experimentally enforced monogamy or polygamy in the bulb mite Rhizoglyphus robini. Three replicates were maintained for each treatment. Monogamy makes male and female interests congruent; thus selection is expected to decrease harmfulness of males to their partners. Our results were consistent with this prediction in that females from monogamous lines achieved lower fecundity when housed with males from polygamous lines. Fecundity of polygamous females was not affected by mating system under which their partners evolved, which suggests that they were more resistant to male-induced harm. As predicted by the antagonistic coevolution hypothesis, the decrease in harmfulness of monogamous males was accompanied by a decline in reproductive competitiveness. In contrast, female fecundity and embryonic viability, which were not expected to be correlated with male harmfulness, did not differ between monogamous and polygamous lines. None of the fitness components assayed differed between individuals obtained from crosses between parents from the same line and those obtained from crosses between parents from different lines within the same mating system. This indicates that inbreeding depression did not confound our results. However, interpretation of our results is complicated by the fact that both males and females from monogamous lines evolved smaller body size compared to individuals from polygamous lines. Although a decrease in reproductive performance of males from monogamous lines was still significant when body size was taken into account, we were not able to separate the effects of male body size and mating system in their influence on fecundity of their female partners. [source] Morphological changes in mouse embryos cryopreserved by different techniquesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 4 2007A.R.S. Coutinho Abstract Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnologies. Subjective evaluation to determine embryo viability is often used. The determination of the best cryopreservation protocol depends on morphological and molecular analysis of cellular injuries. The main objective of this study was to compare two methods of cryopreservation by assessing morphological alterations of frozen embryos using light, fluorescence, and transmission electron microscope. Fresh (control), slow frozen, and vitrified mouse embryos were composed. To evaluate the viability of the embryos, the cell membrane integrity was assessed using Hoechst33342 and propidium iodide (H/PI) staining. Morphological analyses using hematoxylin and eosin (HE) staining were performed to test different techniques (in situ, paraffin, and historesin) by both light and fluorescence microscopy. Transmission electron microscope was used to detect ultrastructural alterations in Spurr- and Araldite-embedded samples. H/PI staining detected more membrane permeability in the vitrification (69.8%) than in the slow freezing (48.4%) or control (13.8%) groups (P < 0.001). Historesin-embedded samples showed to be more suitable for morphological analyses because cellular structures were better identified. Nuclear evaluation in historesin sections showed the induction of pycnosis in slow freezing and vitrification groups. Cytoplasm evaluation revealed a condensation and an increase in eosinophilic intensity (indicating apoptosis) in the slow freezing group, and weakly eosinophilic structures and degenerated cells (indicating oncosis) in the vitrification group (P < 0.05). Ultrastructural analyses confirmed HE morphological findings. It was concluded that both cryopreservation techniques resulted in oncosis and apoptosis injuries. However, vitrification caused more severe cellular alterations and reduced embryonic viability compared to slow freezing. Microsc. Res. Tech., 2007. © 2006 Wiley-Liss, Inc. [source] Embryonic development in the reduced folate carrier knockout mouse is modulated by maternal folate supplementation,,BIRTH DEFECTS RESEARCH, Issue 7 2008Janee Gelineau-van Waes Abstract BACKGROUND: The reduced folate carrier (RFC1) is a ubiquitously expressed integral membrane protein that mediates delivery of 5-methyltetrahydrofolate into mammalian cells. In this study, embryonic/fetal development is characterized in an RFC1 knockout mouse model in which pregnant dams receive different levels of folate supplementation. METHODS:RFC1+/, males were mated to RFC1+/, females, and pregnant dams were treated with vehicle (control) or folic acid (25 or 50 mg/kg) by daily subcutaneous injection (0.1 mL/10 g bwt), beginning on E0.5 and continuing throughout gestation until the time of sacrifice. RESULTS: Without maternal folate supplementation, RFC1 nullizygous embryos die shortly postimplantation. Supplementation of pregnant dams with 25 mg/kg/day folic acid prolongs survival of mutant embryos until E9.5,E10.5, but they are developmentally delayed relative to wild-type littermates, display a marked absence of erythropoiesis, severe neural tube and limb bud defects, and failure of chorioallantoic fusion. Fgfr2 protein levels are significantly reduced or absent in the extraembryonic membranes of RFC1 nullizygous embryos. Maternal folate supplementation with 50 mg/kg/day results in survival of 22% of RFC1 mutants to E18.5, but they develop with multiple malformations of the eyelids, lungs, heart, and skin. CONCLUSIONS: High doses of daily maternal folate supplementation during embryonic/fetal development are necessary for early postimplantation embryonic viability of RFC1 nullizygous embryos, and play a critical role in chorioallantoic fusion, erythropoiesis, and proper development of the neural tube, limbs, lungs, heart, and skin. Birth Defects Research (Part A), 2008. © 2008 Wiley-Liss, Inc. [source] Hypoglycemia induced changes in cell death and cell proliferation in the organogenesis stage embryonic mouse heartBIRTH DEFECTS RESEARCH, Issue 3 2004Gautam S. Ghatnekar Abstract BACKGROUND Hypoglycemia is a side effect of diabetes therapy and causes abnormal heart development. Embryonic heart cells are largely resistant to teratogen-induced apoptosis. METHODS Hypoglycemia was tested for effects on cell death and cell proliferation in embryonic heart cells by exposing mouse embryos on embryonic day (E) 9.5 (plug = E0.5) to hypoglycemia (30,50 mg/dl glucose) in vivo or in vitro for 24 hr. Long-term effects of in vivo exposure on conceptus viability were evaluated at E18.5. Cell death was evaluated on E10.5 by: 1) two TUNEL assays in sectioned embryos to demonstrate DNA fragmentation; 2) confocal microscopy in whole embryos stained with Lysotracker; 3) flow cytometry in dispersed heart cells stained for TUNEL and myosin heavy chain (MHC) to quantify and characterize cell type susceptibility; and 4) immunohistochemistry (IHC) and Western analysis in sectioned embryos to evaluate potential involvement of caspase-3 active subunit and p53. Effects on cell proliferation were evaluated by IHC and Western analysis of proliferating cell nuclear antigen (PCNA). RESULTS In vivo hypoglycemic exposure on E9.5 reduced viability in conceptuses examined on E18.5. Hearts examined on E10.5 demonstrated increased TUNEL and Lysotracker staining. In hearts of embryos exposed to hypoglycemia, flow cytometry demonstrated increased TUNEL-positive cells and cells dual-labeled for TUNEL and MHC. Protein expression of caspase-3 active subunit and p53 was increased and PCNA was markedly reduced in hearts of embryos exposed to hypoglycemia. CONCLUSIONS Hypoglycemia reduces embryonic viability, induces significant cell death, and reduces cell proliferation in the E9.5 mouse heart, and these processes may involve active caspase-3 and p53. Birth Defects Research (Part A), 2004. © 2004 Wiley-Liss, Inc. [source] | ||||||||||