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Embryonic Survival (embryonic + survival)
Selected AbstractsCooler temperatures increase sensitivity to ultraviolet B radiation in embryos and larvae of the frog Limnodynastes peroniiGLOBAL CHANGE BIOLOGY, Issue 6 2007VINCENT O. Van UITREGT Abstract Recent studies suggest that complex interacting processes are driving global amphibian declines. Increased ultraviolet B (UVB) radiation in the solar spectrum associated with ozone depletion has been implicated in declines, and evidence suggests that the effects of UVB radiation on amphibians may be greater at cooler temperatures. We tested the thermal sensitivity of UVB effects on amphibians in a controlled factorial experiment using the striped marsh frog, Limnodynastes peronii as a model species. We compared survival, growth and locomotor performance of embryonic and larval L. peronii reared under low and high UVB exposures at both 20 and 30 °C. Embryonic and larval L. peronii proved extremely sensitive to UVB damage and exhibited greater sensitivity at 20 °C compared with 30 °C. Embryonic survival to Gosner stage 25 was unaffected by UVB exposure at 30 °C, but at 20 °C survival was reduced to 52% under high UVB. Larval survival exhibited a similar trend. At 20 °C, all tadpoles survived under low UVB, whereas under high UVB there was 100% mortality after 15 days of exposure. At 30 °C, 86% survived under low UVB, but only 46% survived under high UVB. Sublethal effects such as, embryonic malformation, retarded larval growth and reduced larval swimming performance were also greater at 20 °C compared with 30 °C. Our results strongly indicate that UVB damage in amphibians is markedly increased at cooler temperatures. Thus, populations of UVB sensitive species occurring at cold climates may be at greater risk of declines due to increased solar UVB radiation. [source] GEOGRAPHIC VARIATION IN ACID STRESS TOLERANCE OF THE MOOR FROG, RANA ARVALIS.EVOLUTION, Issue 2 2003Abstract Spatially varying directional selection together with restricted gene flow among populations is expected to lead to local adaptation. One environmental factor that potentially causes strong directional selection, but is little explored in evolutionary terms, is naturally and anthropogenically induced acidity. We studied local adaptation to acidity in four Swedish populations (two originating from areas that have suffered from severe anthropogenic acidification during the 1900s and two from areas which have remained neutral due to higher buffering capacity) of the moor frog Rana arvalis in a laboratory experiment by investigating whether differences in acid tolerance correspond to population origin. Embryos were raised from fertilization to hatching at three different pH levels (pH 4.0, 4.25 and 7.5), corresponding to levels experienced by these populations in nature, and acid stress tolerance was measured in terms of embryonic survival, hatchling size, and age. Evidence for local adaptation in all of these traits was found, the acid origin embryos having higher survival and less impaired growth performance under acid conditions than the neutral origin embryos. Our estimated rates of divergence (0.007,0.102 haldanes) suggest a rapid adaptation process in response to anthropogenic environmental change, and that the different traits have evolved at relatively similar rates. [source] Mechanisms of Regulation of Litter Size in Pigs on the Genome LevelREPRODUCTION IN DOMESTIC ANIMALS, Issue 2007O Distl Contents Improvement in litter size has become of great interest in pig industry as good fecundity is directly related to a sow's productive life. Genetic regulation of litter size is complex and the main component traits so far defined are ovulation rate, embryonic survival, uterus capacity, foetal survival and pre-weaning losses. Improvements using concepts of the quantitative genetics let expect only slow genetic progress due to its low heritability of approximately 0.09 for number of piglets born alive. Marker assisted selection allows to dissect litter size in its component traits and using molecular genetic markers for the components of litter size traits promises more progress and advantages in optimum balancing of the different physiological mechanisms influencing litter size. In this review, efforts being made to unravel the genetic determinants of litter size are accounted and discussed. For litter size traits, more than 50 quantitative trait loci (QTL) were mapped and in more than 12 candidate genes associations confirmed. The number of useful candidate genes is much larger as shown by expression profiles and in addition, much more QTL can be assumed. These functional genomic approaches, both QTL mapping and candidate gene analysis, have to be merged for a better understanding of a wider application across different pig breeds and lines. Newly developed tools based on microarray techniques comprising DNA variants or expressed tags of many genes or even the whole genome appear useful for in depth understanding of the genetics of litter size in pigs. [source] Litter Characteristics of Gilts Artificially Inseminated with Transforming Growth Factor-,AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2006Michelle Rhodes Problem, Semen is a rich source of transforming growth factor- , (TGF- ,) and it has been proposed that this molecule promotes embryonic survival by modifying immune responses to promote tolerance toward paternal antigens and by inducing release of cytokines that promote embryonic development. The role of TGF- , was tested using pigs by evaluating whether its addition to washed sperm improves conceptus survival and fetal growth. Methods of study, At estrus, gilts were artificially inseminated twice at 12-hr intervals with 100 mL of either washed semen resuspended in a commercial semen extender supplemented with 2 mg/mL of gelatin or washed semen in the same extender containing 65 ng/mL of TGF- ,1. Three boars were used as semen donors. At day 80 (±4 days) of gestation, gilts were sacrificed and reproductive tracts harvested. Results, Treatment had no effect (P > 0.10) on total or live fetuses per litter, implantation rate, fetal survival or percentage of corpora lutea resulting in live fetuses at day 80. Insemination with TGF- ,1 also did not affect total or average fetal weight or total placental weight. There was a tendency (P = 0.09) for average placental weight of live fetuses to be lower for pregnancies established in gilts treated with TGF- ,1. Also, placental efficiency (mass of fetus/mass of placenta) was greater (P < 0.05) for pregnancies established in gilts treated with TGF- ,1. The high fertility in control gilts (80% implantation rate and 11.5 live fetuses per litter) is indicative that soluble seminal factors are not necessary for the establishment of pregnancy. Conclusions, Within the ranges tested, concentration of TGF- , in the fluid phase of the inseminate is not an important determinant of conceptus survival or fetal and placental growth to day 80 of gestation in the pig. [source] Analysis of segregation distortion and association of the bovine FGF2 with fertilization rate and early embryonic survivalANIMAL GENETICS, Issue 5 2009X. Wang Summary Fibroblast growth factor 2 (FGF2) plays an important role in fertility and early embryo development. The objectives of this study were to test the association of FGF2 polymorphisms with fertilization success in cattle using an in vitro fertilization experimental system and to investigate the mechanisms leading to the presence of rare alleles of FGF2 in the Holstein population. A total of 7502 fertilizations were performed and a total of 5049 embryos were produced to collect fertilization and embryo survival records. A total of 444 ovaries, from which oocytes were aspirated and fertilized, were genotyped for two single nucleotide polymorphisms (SNPs) previously identified in FGF2 (g.23G>T and g.11646A>G). Frequency of the TT genotype of the g.23G>T SNP was low in the ovary population (5.4%) and in a different Holstein cattle population (6.6%) examined in this study. Single SNP analysis showed that both SNPs were associated with early embryonic survival rate. Two-way interaction analysis revealed significant association of epistatic interaction between the SNPs with fertilization rate. To test whether or not low frequency of allele T for the g.23G>T SNP in the population is a result of a fertilization failure of T oocytes, semen from six GG bulls was used to fertilize a total of 458 oocytes obtained from 19 GT ovaries. A significant segregation distortion was observed for 169 embryos genotyped for the g.23G>T SNP. We conclude that oocytes carrying the T allele show a reduced fertilization rate and that segregation distortion leads to rarity of the TT genotype in the population. [source] Calf production from vitrified bovine sexed embryos following in-straw dilutionANIMAL SCIENCE JOURNAL, Issue 4 2010Kiyoshi AKIYAMA ABSTRACT The objective of this study was to develop an in-straw dilution method suitable for direct transfer of vitrified bovine sexed embryos. Embryo sexing was performed by molecular diagnosis. Several sexed and vitrified-warmed embryos were transferred after evaluation of morphologically embryonic survival at warming and in-straw dilution (Evaluation group). The other embryos were immediately directly transferred to recipients without first being expelled from the straws after in-straw dilution (Non-evaluation group). The pregnancy rates of vitrified sexed embryos were 38.7% and 34.8% in the Evaluation group and Non-evaluation group, respectively, which were not significantly different. The viability of lower quality embryos before vitrification tended to be lower (P = 0.087) than that of the higher quality embryos regardless of evaluating embryos after warming and in-straw dilution. The abortion rates were similar, and there was no difference between the two groups (13.9% and 12.5%, respectively). These results demonstrate that vitrified bovine sexed embryos can be vitrified and diluted by the in-straw method and that the vitrified and warmed sexed embryos can develop to term. [source] | |||||||||||||