Genetic prenatal maternal effects on organ size in mice and their potential contribution to evolution

Two embryo transfer experiments were carried out in order to estimate the magnitude of prenatal maternal effects, independent of postnatal maternal factors, on the growth of internal organs and fat pads in mice. Reciprocal embryo transfers between the inbred mouse strains C3HeB/FeJ and SWR/J yielded three significant findings. First, all traits were not equally influenced by prenatal maternal factors. Genetic prenatal maternal factors, stemming from the genotype of the uterine mother, had a significant effect on testis weight, subcutaneous fat pad weight and epididymal fat pad weight in 21 day old progeny, but they had no effect on cranial capacity, an index of brain size, kidney weight, or liver weight. Prenatal litter size, defined as the sum of live and dead pups at birth, had a significant negative relationship with 21 day testis weight and kidney weight, and a significant positive association with subcutaneous and epididymal fat pad weights. Cranial capacity and liver weight at 21 days postnatally were not influenced by prenatal litter size. Second, the experiments demonstrated that there was ontogenetic variability in the strength of prenatal maternal effects. At 70 days of age, only subcutaneous fat pad weight was significantly influenced by genetic prenatal effects, and prenatal litter size had a significant negative relationship only with subcutaneous fat pad weight and body weight. Third, genetic prenatal effects had a significant influence on the among-trait covariances at 21 days postnatally, but not at 70 days. Because multivariate evolution involves covariances among characters, the latter results suggest that prenatal effects due to the mother's genotype can affect phenotypic evolution of mammals, especially for selection imposed early in life.     

Response characteristics of the mitochondrial DNA genome in developmental health and disease

This review focuses on mitochondrial biology in mammalian development; specifically, the dynamics of information transfer from nucleus to mitochondrion in the regulation of mitochondrial DNA genomic expression, and the reverse signaling of mitochondrion to nucleus as an adaptive response to the environment. Data from recent studies suggest that the capacity of embryonic cells to react to oxygenation involves a tradeoff between factors that influence prenatal growth/development and postnatal growth/function. For example, mitochondrial DNA replication and metabolic set points in nematodes may be determined by mitochondrial activity early in life. The mitochondrial drug PK11195, a ligand of the peripheral benzodiazepine receptor, has antiteratogenic and antidisease action in several developmental contexts in mice. Protein malnutrition during early life in rats can program mitochondrial DNA levels in adult tissues and, in humans, epidemiological data suggest an association between impaired fetal growth and insulin resistance. Taken together, these findings raise the provocative hypothesis that environmental programming of mitochondrial status during early life may be linked with diseases that manifest during adulthood. Genetic defects that affect mitochondrial function may involve the mitochondrial DNA genome directly (maternal inheritance) or indirectly (Mendelian inheritance) through nuclear-coded mitochondrial proteins. In a growing number of cases, the depletion of, or deletion in, mitochondrial DNA is seen to be secondary to mutation of key nuclear-coded mitochondrial proteins that affect mitochondrial DNA replication, expression, or stability. These defects of intergenomic regulation may disrupt the normal cross-talk or structural compartmentation of signals that ultimately regulate mitochondrial DNA integrity and copy number, leading to depletion of mitochondrial DNA.     

Neurodevelopmental outcomes following prenatal exposure to serotonin reuptake inhibitor antidepressants: A "social teratogen" or moderator of developmental risk?

Understanding how prenatal serotonin reuptake inhibitors (SRIs) influence early brain development can provide critical clues to how early life experience programs developing neural systems that might contribute to risks for illness across the life span. To date, no gross SRI-related neuroteratogenic effects have been identified, but evidence of subtle functional behavioral disturbances associated with fetal SRI exposure are emerging. Although some outcomes reflect a "main effect" for the SRI exposure, childhood development beyond infancy appears typical or continues to be influenced by life with a mother with a mood disturbance. Research shows that not all infants and children are equally affected; thus appreciating the effects of prenatal and postnatal maternal mental illness and of genetic variations that influence early serotonin signaling offers critical new insights into factors that contribute to developmental risk, plasticity, and resiliency in children with prenatal SRI exposure. Such a developmental perspective should lead us to understand what heightens or lessens neurodevelopmental vulnerability, thereby optimizing maternal pharmacotherapy and identifying who benefits and is least likely to experience neurobehavioral disturbances. Birth Defects Research (Part A) 94:651-659, 2012. ? 2012 Wiley Periodicals, Inc.     

Links between parental life histories of wild salmon and the telomere lengths of their offspring

The importance of parental contributions to offspring development and subsequent performance is self‐evident at a genomic level; however, parents can also affect offspring fitness by indirect genetic and environmental routes. The life history strategy that an individual adopts will be influenced by both genes and environment; and this may have important consequences for offspring. Recent research has linked telomere dynamics (i.e., telomere length and loss) in early life to future viability and longevity. Moreover, a number of studies have reported a heritable component to telomere length across a range of vertebrates, although the effects of other parental contribution pathways have been far less studied. Using wild Atlantic salmon with different parental life histories in an experimental split‐brood in vitro fertilization mating design and rearing the resulting families under standardized conditions, we show that there can be significant links between parental life history and offspring telomere length (studied at the embryo and fry stage). Maternal life history traits, in particular egg size, were most strongly related to offspring telomere length at the embryonic stage, but then became weaker through development. In contrast, paternal life history traits, such as the father's growth rate in early life, had a greater association in the later stages of offspring development. However, offspring telomere length was not significantly related to either maternal or paternal age at reproduction, nor to paternal sperm telomere length. This study demonstrates both the complexity and the importance of parental factors that can influence telomere length in early life.     

Dynamic changes in DNA methylation during embryonic and postnatal development of an altricial wild bird

DNA methylation could shape phenotypic responses to environmental cues and underlie developmental plasticity. Environmentally induced changes in DNA methylation during development can give rise to stable phenotypic traits and thus affect fitness. In the laboratory, it has been shown that the vertebrate methylome undergoes dynamic reprogramming during development, creating a critical window for environmentally induced epigenetic modifications. Studies of DNA methylation in the wild are lacking, yet are essential for understanding how genes and the environment interact to affect phenotypic development and ultimately fitness. Furthermore, our knowledge of the establishment of methylation patterns during development in birds is limited. We quantified genome‐wide DNA methylation at various stages of embryonic and postnatal development in an altricial passerine bird, the great tit Parus major. While, there was no change in global DNA methylation in embryonic tissue during the second half of embryonic development, a twofold increase in DNA methylation in blood occurred between 6 and 15 days posthatch. Though not directly comparable, DNA methylation levels were higher in the blood of nestlings compared with embryonic tissue at any stage of prenatal development. This provides the first evidence that DNA methylation undergoes global change during development in a wild bird, supporting the hypothesis that methylation mediates phenotypic development. Furthermore, the plasticity of DNA methylation demonstrated during late postnatal development, in the present study, suggests a wide window during which DNA methylation could be sensitive to environmental influences. This is particularly important for our understanding of the mechanisms by which early‐life conditions influence later‐life performance. While, we found no evidence for differences in genome‐wide methylation in relation to habitat of origin, environmental variation is likely to be an important driver of variation in methylation at specific loci.     

精子sncRNAs在环境暴露相关跨代遗传中的作用

哺乳动物胚胎发育受遗传和表观遗传的共同调控.精子作为重要的雄性生殖细胞,通过受精过程,将这些信息传递给卵子,进而影响子代的发育.精子中携带有丰富的表观遗传信息,其中小非编码RNAs(small noncoding RNAs,sncRNAs)在精子发育不同阶段发挥重要的作用,包括调控基因表达、介导蛋白质翻译,以及参与精子...     

Consistency of passerine embryo development and the use of embryonic staging in studies of hatching failure

Hatching failure is widespread in birds, and is usually the result of embryo death rather than infertility. Embryo death can result from both intrinsic and extrinsic factors, some of which may vary across the developmental period. Determining the point at which an embryo died during development may therefore help us to understand the underlying cause of death. Here we describe simple criteria that can be used by field ornithologists to establish the developmental stage of dead embryos found in unhatched passerine eggs, and explain how this can be used to estimate the date of embryo death. We compared the pattern of embryo development over the incubation period for three species, the Zebra Finch Taeniopygia guttata, Blue Tit Cyanistes caeruleus and Great Tit Parus major. We also compared rates of Zebra Finch embryo development under artificial and standard (parental) incubation. Embryo development rates were remarkably similar across the three species and between Zebra Finch embryos under artificial and natural incubation conditions. We therefore suggest that the pattern of embryo development in the Zebra Finch may provide a model for other small passerines with similar incubation periods, but acknowledge that further interspecific comparisons are required before this model is considered more widely applicable. By estimating embryo death dates using our approach, ornithologists will be able to determine temporal patterns of embryo mortality in relation to extrinsic environmental conditions. This approach may shed light on how extrinsic factors such as climate and parental behaviour influence embryo survival in wild birds.     

Phenotypic plasticity in a complex world: interactive effects of food and temperature on fitness components of a seed beetle

Most studies of phenotypic plasticity investigate the effects of an individual environmental factor on organism phenotypes. However, organisms exist in an ecologically complex world where multiple environmental factors can interact to affect growth, development and life histories. Here, using a multifactorial experimental design, we examine the separate and interactive effects of two environmental factors, rearing host species (Vigna radiata, Vigna angularis and Vigna unguiculata) and temperature (20, 25, 30 and 35°C), on growth and life history traits in two populations [Burkina Faso (BF) and South India (SI)] of the seed beetle, Callosobruchus maculatus. The two study populations of beetles responded differently to both rearing host and temperature. We also found a significant interaction between rearing host and temperature for body size, growth rate and female lifetime fecundity but not larval development time or larval survivorship. The interaction was most apparent for growth rate; the variance in growth rate among hosts increased with increasing temperature. However, the details of host differences differed between our two study populations; the degree to which V. unguiculata was a better host than V. angularis or V. radiata increased at higher temperatures for BF beetles, whereas the degree to which V. unguiculata was the worst host increased at higher temperatures for SI beetles. We also found that the heritabilities of body mass, growth rate and fecundity were similar among rearing hosts and temperatures, and that the cross-temperature genetic correlation was not affected by rearing host, suggesting that genetic architecture is generally stable across rearing conditions. The most important finding of our study is that multiple environmental factors can interact to affect organism growth, but the degree of interaction, and thus the degree of complexity of phenotypic plasticity, varies among traits and between populations.     

Biological rhythms in birds — development, insights and perspectives

The aim of this review is to show that probably the internal clock of precocial birds is imprinted in the prenatal period by exogenous factors (zeitgeber). The activity of organ functions occurs early during embryonic development, before this function is ultimately necessary to ensure the survival of the embryo. Prenatal activation of some functional systems may have a training effect on the postnatal efficiency.The development of physiological control systems is influenced by endogenous and exogenous factors during the late prenatal and early postnatal period: epigenetic adaptation processes play an important role in the development of animals; they have acquired characteristics which are innated but not genetically fixed. As a rule, the actual value during the determination period has a very strong influence on the set-point of the system. This will be explained using the example of thermoregulation.It is shown in detail that it seems to be possible to imprint the prenatal development of circadian rhythms by periodic changes of the light-dark cycle but not by rhythmic influence of acoustic signals.Altogether, there are more questions open than solved concerning the perinatal genesis of circadian rhythms in birds. Topics are given for the future research.     

Biological rhythms in birds--development, insights and perspectives

The aim of this review is to show that probably the internal clock of precocial birds is imprinted in the prenatal period by exogenous factors (zeitgeber). The activity of organ functions occurs early during embryonic development, before this function is ultimately necessary to ensure the survival of the embryo. Prenatal activation of some functional systems may have a training effect on the postnatal efficiency. The development of physiological control systems is influenced by endogenous and exogenous factors during the late prenatal and early postnatal period: epigenetic adaptation processes play an important role in the development of animals; they have acquired characteristics which are innated but not genetically fixed. As a rule, the actual value during the determination period has a very strong influence on the set-point of the system. This will be explained using the example of thermoregulation. It is shown in detail that it seems to be possible to imprint the prenatal development of circadian rhythms by periodic changes of the light-dark cycle but not by rhythmic influence of acoustic signals. Altogether, there are more questions open than solved concerning the perinatal genesis of circadian rhythms in birds. Topics are given for the future research.     

Recognizing the enemy: do predator cues influence hatching in Neotropical annual killifish?

Annual fish species have evolved complex adaptations to survive in temporary wetlands. The main adaptation of these fish is the ability to produce embryos that survive dry periods. Embryo development of this fish can show variation at multiple levels influenced by many environmental factors, such as photoperiod and temperature. Predator cues are another factor that can influence the embryonic stage. One way in which annual fish could adapt to predators is by using risk-spreading strategies (through bet-hedging). Nonetheless, this strategy depends on the coevolutionary history between predators and preys and on the degree of environmental unpredictability, resulting in different responses across different species. This study investigated the influence of predator cues on the embryonic development and hatching of two Austrolebias species that inhabit ponds that present differences in hydroperiod and the risk of predator presence. The results confirmed a differentiated response between the two annual fish species tested, corroborating the modulation of hatching against the risk of predation by native predatory fish. The authors further showed that development times varied between the two annual fish species, regardless of the presence of predators. They highlight that the variation in embryonic development is strongly affected by different levels of hydroperiod unpredictability faced by the two species. To unravel finer-scale local adaptations in the annual fish embryo development, future studies should focus on a region with greater spatial gradient.     

Embryogenesis plasticity and the transmission of maternal effects in Daphnia pulex

Understanding how genetic, nongenetic, and environmental cues are integrated during development may be critical in understanding if, and how, organisms will respond to rapid environmental change. Normally, only post‐embryonic studies are possible. But in this study, we developed a real‐time, high‐throughput confocal microscope assay that allowed us to link Daphnia embryogenesis to offspring life history variation at the individual level. Our assay identified eight clear developmental phenotypes linked by seven developmental stages, the duration of which were correlated with the expression of specific offspring life history traits. Daphnia embryogenesis varied not only between clones reared in the same environment, but also within a single clone when mothers were of different ages or reared in different food environments. Our results support the hypothesis that Daphnia embryogenesis is plastic and can be altered by changes in maternal state or maternal environment. As well as furthering our understanding of the mechanisms underpinning parental effects, our assay may also have an industrial application if it can be used as a rapid ecotoxicological prescreen for testing the effect that pollutant doses have on offspring life histories traditionally assayed with a 21‐day Daphnia reproduction test.     

Prenatal diagnosis of genetic disorders in preimplantation embryos: invasive and non-invasive approaches

Summary The purpose of this article is to analyse the various non-invasive and invasive methods that offer the opportunity of prenatal diagnosis of selected inherited disorders at the preimplantation stages of human embryonic development and to discuss the advantages and ethical problems associated with such procedures. These investigations should also provide important information on the development of the human embryo and its hormonal and immunological relationship with the mother.     

Nongenomic memory of foetal history in chronic diseases development

Foetal growth from conception to birth is a complex process predetermined by the genetic configuration of the foetus, the availability of nutrients and oxygen to the foetus, maternal nutrition and various growth factors and hormones of maternal, foetal and placental origin. Maintenance of the optimal foetal environment is the key factor of the future quality of life. Such conditions like inadequate nutrition and oxygen supply, infection, hypertension, gestational diabetes or drug abuse by the mother, expose the foetus to nonphysiological environment. In conditions of severe intrauterine deprivation, there is a potential loss of structural units within the developing organ systems affecting their functionality and efficiency. Extensive human epidemiologic and animal model data indicate that during critical periods of prenatal and postnatal mammalian development, nutrition and other environmental stimuli influence developmental pathways and thereby induce permanent changes in metabolism and chronic disease susceptibility. The studies reviewed in this article show how environmental factors influence a diverse array of molecular mechanisms and consequently alter disease risk including diseases such as metabolic syndrome and cardiovascular diseases, insulin resistance and diabetes mellitus, neuropsychiatric disorders, osteoporosis, asthma and immune system diseases.     

The effects of the early uterine environment on the subsequent development of embryo and fetus

Synchrony between the embryo and the uterine endometrium is essential for the establishment of pregnancy and birth in people and livestock. When asynchronous conditions occur a variety of complication result that include failure of the embryo to implant, early embryonic mortality, retarded development and growth, and accelerated development and growth. These complications all appear to be induced within the first week of embryo development and not withstanding the immediate endpoint of large or small size at birth, may alter the course of development throughout the life of the animal. Progesterone appears to play a causative role in establishing the abnormal growth of the fetus by decelerating or accelerating embryonic development. This may act through increasing the transport of blood born growth factors into the uterine lumen or by stimulating the release of growth factors from the endometrium directly. It can not be ruled out that progesterone mediated abundance of, or absence of, appropriate nutrition may bring about the same lifelong outcome. In vitro culture situations that include serum and/or co-culture can also bring about these abnormalities of growth. It is hypothesized that exposure to growth factors "out of phase" may result in an irreversible induction of abnormal development. The described abnormalities that occur in sheep and cattle have not yet been described for children resulting from IVF.     

Factors affecting the survival of sheep embryos after transfer within a MOET program

Multiple ovulation and embryo transfer (MOET) has the potential to increase the rate of genetic improvement in sheep. However, better realization of this potential requires maximum survival rates of transferred embryos of high genetic merit after transfer into recipient ewes. These studies were therefore conducted to investigate the effect of both embryonic and recipient ewe factors on the survival rate of transferred embryos. Survival rate was similar after transfer of morula or blastocyst stage embryos, and these were higher (P<0.05) than for very early morulae and early morulae. Advanced embryos (Day 5 blastocyst) had an advantage (P<0.05) in survival rate over retarded embryos (Day 6 morula). Grades 1 and 2 embryos survived significantly (P<0.05) better than Grades 3 or 4 embryos. There was no difference in embryo survival rate following transfer to recipients with different numbers of corpora lutea. In general, age or parity of recipient ewes did not affect embryo survival rate, although a higher (P<0.05) embryo survival rate was observed for yearling recipients. Buserelin (GnRH agonist) treatment of recipient ewes 5 or 6 days after transfer of embryos (Day 12 of the cycle) did not improve embryo survival rate. These results confirm that both embryonic and recipient factors can play an important role in the success of a MOET program in sheep.     

Role of epigenetics in developmental biology and transgenerational inheritance

The molecular mechanisms involved in developmental biology and cellular differentiation have traditionally been considered to be primarily genetic. Environmental factors that influence early life critical windows of development generally do not have the capacity to modify genome sequence, nor promote permanent genetic modifications. Epigenetics provides a molecular mechanism for environment to influence development, program cellular differentiation, and alter the genetic regulation of development. The current review discusses how epigenetics can cooperate with genetics to regulate development and allow for greater plasticity in response to environmental influences. This impacts area such as cellular differentiation, tissue development, environmental induced disease etiology, epigenetic transgenerational inheritance, and the general systems biology of organisms and evolution.     

Quantitative genetics of growth and development time in the burying beetle Nicrophorus pustulatus in the presence and absence of post-hatching parental care

Despite a growing interest in the evolutionary aspects of maternal effects, few studies have examined the genetic consequences of maternal effects associated with parental care. To begin to provide data on nonlaboratory or nondomestic animals, we compared the effect of presence and absence of parental care on phenotype expression of larval mass and development time at different life-history stages in the burying beetle Nicrophorus pustulatus. This beetle has facultative care; parents can feed their larvae through regurgitation of digested carrion or offspring can feed by themselves from previously prepared carrion. To investigate larval responses to these two levels of care, including estimates of additive genetic effects, maternal effects, and genotype-by-environment interactions, we used a half-sibling split-family breeding experiment-raising half of the offspring of a family in the presence of their mother and the other half without their mother present. Larvae reared with their mother present were on average heavier and developed faster, although some of the differences in development decreased or were eliminated by the adult stage. These results suggest that presence or absence of post-hatching maternal care plays an important role in phenotype expression early in life, whereas later the phenotype of the offspring is determined mainly by the genotype and/or unshared environmental effects. Our study also permitted us to examine the differences in genetic effects between the two care environments. Heritabilities, maternal/common environment effect, and most genetic correlations did not differ between the care treatments. Genetic analyses revealed substantial additive genetic effects for development time but small effects for measures of body mass. Maternal plus common environment effects were high for measures of mass but low for development time, suggesting that indirect genetic effects of maternal and/or common environment are less important for the evolution of development time than for mass. Estimates of genetic correlations revealed a trade-off between the duration of the two development stages after the offspring left the carrion. There was also a negative genetic correlation between the time spent on carrion and the mass at 72 h, when mothers usually stop feeding. The analysis of genotype-by-environment interactions indicates substantial variation among maternal families in response to care. Presence or absence of parental care may therefore contribute to the additive genetic variance through its interaction with the maternal component of the additive genetic variance. The presence of this interaction further suggests that parents may vary in care strategies, with some parents dispersing after preparation of the carrion and some parents staying with the larvae. This interaction may help maintain genetic variation in growth, development time, and parental care behavior. Additional work is needed, however, to quantify indirect genetic effects and genetic variation in parental care behavior itself.     

An age–size reaction norm yields insight into environmental interactions affecting life‐history traits: a factorial study of larval development in the malaria mosquito Anopheles gambiae sensu stricto

Environmental factors frequently act nonindependently to determine growth and development of insects. Because age and size at maturity strongly influence population dynamics, interaction effects among environmental variables complicate the task of predicting dynamics of insect populations under novel conditions. We reared larvae of the African malaria mosquito Anopheles gambiae sensu stricto (s.s.) under three factors relevant to changes in climate and land use: food level, water depth, and temperature. Each factor was held at two levels in a fully crossed design, for eight experimental treatments. Larval survival, larval development time, and adult size (wing length) were measured to indicate the importance of interaction effects upon population‐level processes. For age and size at emergence, but not survival, significant interaction effects were detected for all three factors, in addition to sex. Some of these interaction effects can be understood as consequences of how the different factors influence energy usage in the context of a nonindependent relationship between age and size. Experimentally assessing interaction effects for all potential future sets of conditions is intractable. However, considering how different factors affect energy usage within the context of an insect's evolved developmental program can provide insight into the causes of complex environmental effects on populations.