Unveiling the distinctive traits of functional rye centromeres:minisatellites,retrotransposons,and R-loop formation

Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting diverse sizes and compositions across species.The functional significance of rye centromeric DNA sequences,particularly in centromere identity,remains unclear.In this study,we comprehensively characterized the sequence composition and organization of rye centromeres.Our findings revealed that these centromeres are primarily composed of long terminal repeat retrotransposons(LTR-RTs)and interspersed minisatellites.We systematically classified LTR-RTs into five categories,highlighting the prevalence of younger CRS1,CRS2,and CRS3 of CRSs(centromeric retrotransposons of Secale cereale)were primarily located in the core centromeres and exhibited a higher association with CENH3 nucleosomes.The minisatellites,mainly derived from retrotransposons,along with CRSs,played a pivotal role in establishing functional centromeres in rye.Additionally,we observed the formation of R-loops at specific regions of CRS1,CRS2,and CRS3,with both rye pericentromeres and centromeres exhibiting enrichment in R-loops.Notably,these R-loops selectively formed at binding regions of the CENH3 nucleosome in rye centromeres,suggesting a potential role in mediating the precise loading of CENH3 to centromeres and contributing to centromere specification.Our work provides insights into the DNA sequence composition,distribution,and potential function of R-loops in rye centromeres.This knowledge contributes valuable information to understanding the genetics and epigenetics of rye centromeres,offering implications for the development of synthetic centromeres in future plant modifications and beyond.

基于SCAR标记和DNA条形码技术的苍术基原鉴别研究

目的开发出能同时鉴别北苍术和关苍术的分子标记方法,并探究不同种质资源苍术的遗传进化关系。方法对不同地区北苍术Atractylodes chinensis(Bunge)Koidz及关苍术A.japonica Koidz.ex Kitam基因组DNA的差异片段进行测序,结合SRAP、ISSR、DAMD分子标记方法,优化PCR反应体系,筛选并转换成特异性标记,同时,采用条形码方法分析种间序列差异。结果通过SRAP、ISSR、DAMD三种分子标记方法的PCR扩增,共筛选出198对能稳定扩增且重现性好的引物,转换出7对能稳定、快速鉴别北苍术和关苍术的SCAR引物。条形码方法检测出北苍术ITS2序列长度为454 bp,关苍术ITS2序列长度为453 bp,与其他苍术属植物之间遗传距离较远。NJ树结果显示,北苍术、关苍术及其他苍术属植物均各自聚为一支,表现出良好的单系性。依据ITS2二级结构,4种苍术属植物在螺旋区的茎环数目、大小、位置均有明显差异,可以直观地进行区分。结论所开发的特异性SCAR标记为苍术属植物优良品种的筛选提供了新方法,DNA条形码能稳定、准确鉴别北苍术。

Fully Distributed Adaptive Fault-Tolerant Attitude Synchronization for a Team of Heterogenous Minisatellites

In this paper,the fault-tolesant attitude aynchronisation aontrol problem for a team of bet-soganua man leatellita in addrsed,subject to multaple actuator faulta and uneertainties in the satellite dynamles.A fully distributed adapSe fault-tokerant controlker,completely inde pendently of the knowledge of the gobal infarmation,is propoaed to achieve the desired attstude aynchranlatin.The attitade tracking aror of the glohal clased-loop eantrol aystem is paoven to onverge into a givan naighborbood of the origin ultimately.Simmlation rasults are givan to validate the afectivenas and advantaga of the propased adaptive controller dor the belerogenaou satellite formation flying team,against the infuenoe of actuator faults and umeertaintin.

Diagnosis and characterization of the ribosomal DNA-ITS of potato rot nematode(Ditylenchus destructor) populations from Chinese medicinal herbs

The potato rot nematode(Ditylenchus destructor) is a very economically important nematode in agronomic and horticultural plants worldwide. In this study, 43 populations of D. destructor were collected from different hosts across China, including 37 populations from Chinese herbal medicine plants. Obtained sequences of ITS-rDNA and D2–D3of 28S-rDNA genes of D. destructor were compared and analyzed. Nine types of significant length variations in ITS sequences were observed among all populations. The differences in ITS1 length were mainly caused by the presence of repetitive elements with substantial base substitutions. Reconstructions of ITS1 secondary structures showed that the minisatellites formed a stem structure. Ten haplotypes were observed in all populations based on mutations and variations of helix H9. Among them, 3 known haplotypes(A–C) were found in 7 populations isolated from potato,sweet potato, and Codonopsis pilosula, and 7 unique haplotypes were found in other 36 populations collected from C. pilosula and Angelica sinensis compared with 7 haplotypes(A–G) according to Subbotin' system. These unique haplotypes were different from haplotypes A–G, and we named them as haplotypes H–N. The present results showed that a total of 14 haplotypes(A–N) of ITS-rDNA have been found in D. destructor. Phylogenetic analyses of ITSrDNA and D2–D3 showed that all populations of D. destructor were clustered into two major clades: one clade only containing haplotype A from sweet potato and the other containing haplotypes B–N from other plants. For further verification, PCR-ITS-RFLP profiles were conducted on 7 new haplotypes. Collectively, our study suggests that D. destructor populations on Chinese medicinal materials are very different from those on other hosts and this work provides a paradigm for relevant researches.

Progress in satellite gravity recovery from implemented CHAMP,GRACE and GOCE and future GRACE Follow-On missions

Firstly, the Earth＇s gravitational field from the past Challenging Minisatellite Payload （CHAMP） mission is determined using the energy conservation principle, the combined error model of the cumulative geoid height influenced by three instrument errors from the current Gravity Recovery and Climate Experiment （GRACE） and future GRACE Follow-On missions is established based on the semi-analytical method, and the Earth＇s gravitational field from the executed Gravity Field and Steady-State Ocean Circulation Explorer （GOCE） mission is recovered by the space-time-wise approach. Secondly, the cumulative geoid height errors are 1.727 × 10^-1 m, 1.839 × 10^-1 m and 9.025 × 10^ -2 m at degrees 70,120 and 250 from the implemented three-stage satellite gravity missions consisting of CHAMP, GRACE and GOCE, which preferably accord with those from the existing earth gravity field models involving EIGEN-CHAMP03S, EICEN-GRACE02S and GO_CONS GCF 2 DIR R1. The cumulative geoid height error is 6.847 × 10 ^-2 m at degree 250 from the future GRACE Follow-On mission. Finally, the complementarity among the four-stage satellite gravity missions including CHAMP, GRACE, GOCE and GRACE Follow-On is demonstrated contrastively.

Rapid identification of the origin of hematopoietic cells after allogeneic hematopoietic stem cell transplantation for leukemia with DNA-fingerprinting

In order to rapidly identify the presence of hematopoietic reconstruction after allogeneic hematopoietic stem cell transplantation (AHCT) for leukemia, we developed a technique for amplifying human hypervariable minisatellite DNA by polymerase chain reaction (PCR) combined with digoxigenin-labeled locus-specific oligonucleotide hybridization. DNA fingerprinting by this technique was used as a specific genetic marker to determine the success rate of engraftment after AHCT in 7 patients with leukemia. Six of them gained evidence of engraftment. The results show that the minisatellite DNA fingerprinting is of high individual specificity and is valuable in confirming engraftment after AHCT, especially when the patient and the donor are HLA identical and of the same sex, and have the same ABO-Rh blood grouping. The advantages of this technique are that there is no contamination by radioisotopes, and its use is not restricted by the half ulife. It is simple and highly sensitive. Engraftment of donor’s hematopoietic cells can be determined as early as 15 d post-transplantation using 100 ng DNA of the patient. We conclude that this technique is highly specific and sensitive, and can rapidly provide in formation about the origin of the hematopoietic cells, thus being of value in guiding early therapeutic intervention in AHCT.

Genetic variation in birds in relation to predation risk by hawks： A comparative analysis

The level of genetic variation among individuals may affect performance by reducing the ability of prey to detect and escape from predators if lack of genetic variation reduces flight ability directly or indirectly through reduced parasite resistance. We investigated vulnerability of common avian prey species to predation by the sparrowhawk Accipiter nisus and the goshawk A. gentilis in relation to an index of genetic similarity among adults of potential prey species. We estimated a prey vulnerability in- dex that reflects the abundance of prey relative to the expected abundance according to local population density, and related this index to band sharing coefficients based on analyses of minisatellites for adults in local breeding populations. The prey vulnera- bility index was positively correlated with the band sharing coefficient in both predators, even when controlling for potentially confounding variables. These findings indicate that prey species with high band sharing coefficients, and hence low levels of genetic variation, are more readily caught by avian predators. Therefore, predation may constitute a major cost of low levels of genetic variation in extant populations of prey [Current Zoology 61（1）： 1-9, 2015].