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Embryo Growth (embryo + growth)
Selected AbstractsIFN-, induces apoptosis in mouse embryonic stem cells, a putative mechanism of its embryotoxicityDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2000Gang-Ming Zou It has been reported that interferon (IFN)-, should inhibit in vitro mouse embryo growth by direct cell toxicity. However, the mechanism involved has not been clearly established. In the present study, this question was addressed using the embryonic stem (ES) cell model. It was found that IFN-, induces a dose-dependent apoptosis in ES cells, as assessed by trypan-blue staining, by Annexin-V labeling and DNA analysis. Moreover, IFN-, treatment cooperates with Fas-mediated apoptosis, a phenomenon that has been recently reported. As Bcl-2 oncoprotein functions as a death repressor molecule in an evolutionarily conserved cell death pathway, its expression was analyzed by flow cytometry. It was demonstrated that Bcl-2 is expressed in ES cells. When compared to untreated ES cells, IFN-,-treated, apoptotic cells expressed a lower Bcl-2 level and a normal level of Fas, whereas surviving cells expressed a normal level of Bcl-2 but a lower Fas expression. Altogether, these data suggest that IFN-, may influence early mouse embryo development by promoting apoptosis, which may constitute a novel mechanism of IFN-, embryotoxicity. [source] Reproductive diapause and the bacterial symbiosis in the sycamore aphid Drepanosiphum platanoidisECOLOGICAL ENTOMOLOGY, Issue 3 2000A. E. Douglas Summary 1. Parthenogenetic adults of the sycamore aphid Drepanosiphum platanoidis exhibited reproductive diapause for 4,6 weeks in the summer. 2. The diapausing aphids had small gonads (accounting for just 13% of the total aphid protein content) bearing small (< 0.5 mm long) and developmentally immature embryos. There was no evidence of embryo resorption. 3. The diapausing aphids had significantly depressed essential amino acid content and elevated glutamine content, relative to reproductively active D. platanoidis. 4. The reproductive characteristics and amino acid titres of the diapausing aphids resemble those of aphids lacking functional symbiotic bacteria. Uncoupling of maternal and embryo growth and suppression of bacterial function are proposed as key elements in the diapause of D. platanoidis. [source] Embryo growth rates in birds and mammalsFUNCTIONAL ECOLOGY, Issue 3 2010Robert E. Ricklefs Summary 1.,Embryo mass growth curves of 36 species of bird and 18 species of mammal were fitted by sigmoidal Gompertz functions, in which k (days,1) describes the rate at which the embryo approaches an asymptotic mass A (g). 2.,The parameters of the Gompertz function were uncorrelated with parameters of power functions fitted to the same growth data, indicating that the two models describe different aspects of growth. 3.,Asymptotes of the Gompertz functions for embryonic growth averaged 2·5 times neonate size, but were well below adult mass. Thus, the pre- and postnatal phases of growth are distinct and have different target sizes. 4.,Embryo growth rate (k) decreases as the ,1/4 power of neonate size; values for mammals were 63% of those of birds, on average. 5.,Embryo growth rate can be predicted solely by the length of the incubation or gestation period, regardless of the size of the neonate, with the same relationship for birds and mammals. 6.,Postnatal growth rate (kG) scales linearly with embryonic growth rate (k), but is nearly five- times more rapid, on average, in birds than in mammals. kG and k have similar magnitude in birds, but kG is relatively much slower than k in mammals. 7.,Rate of actuarial senescence , (year,1), measured by the increase in mortality rate with age, is positively related to the rate of embryo growth in both birds and mammals, but is higher in the latter. Moreover, rate of ageing in birds is uniquely related to embryo growth while that in mammals is uniquely related to postnatal growth rate. Thus, development and ageing appear to be differently connected in birds and mammals, although the basis for these relationships is not known. [source] Temperature conditions control embryo growth and seed germination of Corydalis solida (L.) Clairv., a temperate forest spring geophytePLANT BIOLOGY, Issue 6 2009F. Vandelook Abstract Spring is often the most suitable period for seedling establishment of temperate woodland species. Different physiological mechanisms resulting in spring emergence have evolved in seeds of such plants. The aim of this study was to determine the requirements for breaking dormancy and for seed germination of the European perennial spring geophyte Corydalis solida (Fumariaceae). Ripe seeds of C. solida contain an underdeveloped embryo, consisting of no more than a clump of cells. As a consequence, the embryo has to differentiate and grow to a critical length before germination can occur. In nature, seeds are dispersed in spring, while growth of the embryo starts in the autumn and continues in winter. Germination starts in late winter, immediately after embryo growth is completed, resulting in seedling emergence in the following spring. Experiments in controlled conditions showed that temperature is the main factor controlling dormancy and germination. Incubation at autumn temperatures (15/6 °C; 20/10 °C) for at least 8 weeks is required to initiate embryo growth, while a transfer to 5 °C is needed for completion of embryo growth and germination. Growth of the embryo of C. solida occurs at different temperatures over an extended period, a feature typical of temperate forest herbs. Our results indicate that the dormancy mechanism in seeds of C. solida is very similar to mechanisms in other Corydalis species studied thus far, suggesting that stasis in the dormancy trait has occurred. [source] Effects of prenatal visual stimulation on growth and heart rate in bobwhite quail (Colinus virginianus)DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2006Merry J. Sleigh Abstract This study examined the effects of prenatal visual stimulation on bobwhite quail embryos' growth and heart rate. No differences in growth rate were found between embryos exposed to visual stimulation during the late prenatal period and control embryos. Embryos exposed to visual stimulation throughout incubation maintained lower heart rates in response to visual stimulation than did naïve embryos. In a subsequent experiment, naïve embryos that underwent an egg-opening procedure exhibited heart rates that were lower than embryos measured in intact eggshells. Embryos in opened eggs maintained lower heart rates than comparison embryos across time; however, a less invasive egg-opening procedure led to a quicker heart rate recovery than did a more invasive egg-opening procedure. These findings indicate that prenatal heart rate responses may be mediated by multiple features of the organism's developmental context, including intensity and duration of sensory stimulation. © 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 315,324, 2006. [source] | ||||||||||