Embryo quality and chromosomal abnormality in embryos from couples undergoing assisted reproductive technology using preimplantation genetic screening

Objective:To detect common chromosomal aneuploidy variations in embryos from couples undergoing assisted reproductive technology and preimplantation genetic screening and their possible associations with embryo quality.Methods:In this study,359 embryos from 62 couples were screened for chromosomes 13,21,18,X,and Y by fluorescence insitu hybridization.For biopsy of blastomere,a laser was used to remove a significantly smaller portion of the zona pellucida.One blastomere was gently biopsied by an aspiration pipette through the hole.After biopsy,the embryo was immediately returned to the embryo scope until transfer.Embryo integrity and blastocyst formation were assessed on day 5.Results:Totally,282 embryos from 62 couples were evaluated.The chromosomes were normal in 199(70.57%)embryos and abnormal in 83(29.43%)embryos.There was no significant association between the quality of embryos and numerical chromosomal abnormality(P=0.67).Conclusions:Embryo quality is not significantly correlated with its genetic status.Hence,the quality of embryos determined by morphological parameters is not an appropriate method for choosing embryos without these abnormalities.

Species identification of crested gibbons(Nomascus) in captivity in China using karyotyping-and PCR-based approaches

Gibbons and siamangs （Hylobatidae） are well-known for their rapid chromosomal evolution,which has resulted in high speciation rate within the family.On the other hand,distinct karyotypes do not prevent speciation,allowing interbreeding between individuals in captivity,and the unwanted hybrids are ethically problematic as all gibbon species are endangered or critically endangered.Thus,accurate species identification is crucial for captive breeding,particularly in China where studbooks are unavailable.Identification based on external morphology is difficult,especially for hybrids,because species are usually similar in appearance.In this study,we employed G-banding karyotyping and fluorescence in situ hybridization （FISH） as well as a PCR-based approach to examine karyotypic characteristics and identify crested gibbons of the genus Nomascus from zoos and nature reserves in China.We characterized and identified five karyotypes from 21 individuals of Nomascus.Using karyotypes and mitochondrial and nuclear genes,we identified three purebred species and three hybrids,including one F2 hybrid between N.gabriellae and N.siki.Our results also supported that N.leucogenys and N.siki shared the same inversion on chromosome 7,which resolves arguments from previous studies.Our results demonstrated that both karyotyping and DNA-based approaches were suitable for identifying purebred species,though neither was ideal for hybrid identification.The advantages and disadvantages of both approaches are discussed.Our results further highlight the importance of animal ethics and welfare,which are critical for endangered species in captivity.

Molecular Cytogenetic Characterization and Stem Rust Resistance of Five Wheat-Thinopyrum ponticum Partial Amphiploids

Partial amphiploids created by crossing common wheat （Triticum aestivum L.） and Thinopyrum ponticum （Podp.） Barkworth ＆ D. R. Dewey are important intermediates in wheat breeding because of their resistance to major wheat diseases. In this study, we examined the chromosome compositions of five Xiaoyan-series wheat-Th, ponticum partial amphiploids （Xiaoyan 68, Xiaoyan 693, Xiaoyan 784, Xiaoyan 7430, and Xiaoyan 7631） using GISH, multicolor-GISH, and multicolor-FISH. We found several chromosome changes in these lines. For example, wheat chromosomes 1B and 2B were added in Xiaoyan 68 and Xiaoyan 7430, respectively, while wheat chromosome 6B was eliminated from Xiaoyan 693 and Xiaoyan 7631. Chromosome rearrangements were also detected in these amphiploids, including an interspecific translocation involving chromosome 4D and some intergenomic translocations, such as A--B and A--D translocations, among wheat genomes. Analysis of the Th. ponticum chromosomes in the amphiploids showed that some lines shared the same alien chromosomes. We also evaluated these partial amphiploids for resistance to nine races of stem rust, including TTKSK （commonly known as Ug99）. Three lines, Xiaoyan 68, Xiaoyan 784, and Xiaoyan 7430, exhibited excellent resistance to all nine races, and could therefore be valuable sources of stem rust resistance in wheat breeding.