Necessity of structural rearrangements for O-O bond formation between O5 and W2 in photosystemⅡ

Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.

Investigation of the genetic etiology in male infertility with apparently balanced chromosomal structural rearrangements by genome sequencing

Apparently balanced chromosomal structural rearrangements are known to cause male infertility and account for approximately 1%of azoospermia or severe oligospermia.However,the underlying mechanisms of pathogenesis and etiologies are still largely unknown.Herein,we investigated apparently balanced interchromosomal structural rearrangements in six cases with azoospermia/severe oligospermia to comprehensively identify and delineate cryptic structural rearrangements and the related copy number variants.In addition,high read-depth genome sequencing(GS)(30-fold)was performed to investigate point mutations causative of male infertility.Mate-pair GS(4-fold)revealed additional structural rearrangements and/or copy number changes in 5 of 6 cases and detected a total of 48 rearrangements.Overall,the breakpoints caused truncations of 30 RefSeq genes,five of which were associated with spermatogenesis.Furthermore,the breakpoints disrupted 43 topological-associated domains.Direct disruptions or potential dysregulations of genes,which play potential roles in male germ cell development,apoptosis,and spermatogenesis,were found in all cases(n=6).In addition,high read-depth GS detected dual molecular findings in case MI6,involving a complex rearrangement and two point mutations in the gene DNAH1.Overall,our study provided the molecular characteristics of apparently balanced interchromosomal structural rearrangements in patients with male infertility.We demonstrated the complexity of chromosomal structural rearrangements,potential gene disruptions/dysregulation and single-gene mutations could be the contributing mechanisms underlie male infertility.

Current Status and Recent Advances in Preimplantation Genetic Testing for Structural Rearrangements

Preimplantation genetic testing(PGT)is an early form of prenatal genetic diagnosis,which can identify the abnormal embryos cultured in vitro,allow only transfer of genetically normal embryos,and improve the pregnancy rate.In recent years,the rapid development of microarrays and next-generation sequencing(NGS)technologies has remarkably accelerated the clinical application of PGT.In particular,a variety of detection methods have emerged and achieved significant progress in PGT for structural rearrangements(PGT-SR).The detection-related abilities of these methods range from the detection of limited chromosome aneuploidy to comprehensive chromosome screening of the whole genome to differentiation of embryos with normal or balanced translocation/inversion karyotypes.In this study,we reviewed PGT-SR-related detection techniques to provide a better reference for clinical application and research.We have also discussed the potential development of novel techniques in the future.

STRUCTURAL REARRANGEMENT AND PROPERTIES OF QUENCHED TITANATE GLASSES REHEATED AT T_g

The structural rearrangement of quenched titanate glasses reheated at T-g was investigated by ESR and IR spectroscopies. Front the ESR observations it is suggested that the structure was readjusted and became more compact after the heat-treatment. A removal of residual vacancies is related to the diffusion of oxygen ions. The combination of more oxygen with titanium ions to form titanium-oxygen polyhedra and the transformation of boron-oxygen groups are confirmed front IR spectra. Some physical properties are improved after heating.

Knowledge-embedded spatio-temporal analysis for euploidy embryos identification in couples with chromosomal rearrangements

Background:The goal of the assisted reproductive treatment is to transfer one euploid blastocyst and to help infertile women giving birth one healthy neonate.Some algorithms have been used to assess the ploidy status of embryos derived from couples with normal chromosome,who subjected to preimplantation genetic testing for aneuploidy(PGT-A)treatment.However,it is currently unknown whether artificial intelligence model can be used to assess the euploidy status of blastocyst derived from populations with chromosomal rearrangement.Methods:From February 2020 to May 2021,we collected the whole raw time-lapse videos at multiple focal planes from in vitro cultured embryos,the clinical information of couples,and the comprehensive chromosome screening results of those blastocysts that had received PGT treatment.Initially,we developed a novel deep learning model called the Attentive Multi-Focus Selection Network(AMSNet)to analyze time-lapse videos in real time and predict blastocyst formation.Building upon AMSNet,we integrated additional clinically predictive variables and created a second deep learning model,the Attentive Multi-Focus Video and Clinical Information Fusion Network(AMCFNet),to assess the euploidy status of embryos.The efficacy of the AMCFNet was further tested in embryos with parental chromosomal rearrangements.The receiver operating characteristic curve(ROC)was used to evaluate the superiority of the model.Results:A total of 4112 embryos with complete time-lapse videos were enrolled for the blastocyst formation prediction task,and 1422 qualified blastocysts received PGT-A(n=589)or PGT for chromosomal structural rearrangement(PGT-SR,n=833)were enrolled for the euploidy assessment task in this study.The AMSNet model using seven focal raw time-lapse videos has the best real-time accuracy.The real-time accuracy for AMSNet to predict blastocyst formation reached above 70%on the day 2 of embryo culture,and then increased to 80%on the day 4 of embryo culture.Combing with 4 clinical features of couples,the AUC of AMCFNet with 7 focal points increased to 0.729 in blastocysts derived from couples with chromosomal rearrangement.Conclusion:Integrating seven focal raw time-lapse images of embryos and parental clinical information,AMCFNet model have the capability of assessing euploidy status in blastocysts derived from couples with chromosomal rearrangement.

A review of pre-implantation genetic testing technologies and applications

The first practice of pre-implantation genetic testing(PGT)was reported more than 30 years ago.PGT,originally named preimplantation genetic screening(PGS)and pre-implantation genetic diagnosis(PGD),is now categorized as PGT for aneuploidies(PGT-A),PGT for monogenic/single-gene defects(PGT-M),and PGT for chromosomal structural rearrangements(PGT-SR).Patients with fertility issues caused by advanced maternal age,carrier status of chromosomal abnormalities,or harboring pathogenic variant(s)are recommended to undergo PGT to increase the possibility of successful live birth and avoid potentially affected newborns.High-throughput techniques,such as DNA microarrays and next-generation sequencing(NGS),have enabled comprehensive screening of all 24 chromosomes,instead of few loci at a time.Furthermore,as a comprehensive PGT,PGT-Plus was enabled by the rapid development of a genome-wide single-cell haplotyping technique to detect embryo aneuploidy,single-gene disorders,and chromosomal aberrations simultaneously using a single universal protocol.In addition,non-invasive approaches enable a more intact embryo during the biopsy procedure,which may avoid potential mosaicism issues at a certain scale by testing spent culture media(SCM).As a novel PGT application,PGT-P detects genome-wide variations in polygenic diseases,which account for a large proportion of premature human deaths and affect a markedly larger population than monogenic diseases,using polygenic risk score calculation to decrease the potential of affecting complex conditions.Owing to the emergence of new technologies recruited to PGTs,more couples with infertility issues have a promising chance of conceiving a healthy baby,ultimately facilitating the human species to live more prosper.