Preferential gene retention increases the robustness of cold regulation in Brassicaceae and other plants after polyploidization

Cold stress profoundly affects plant growth and development and is a key factor affecting the geographic distribution and evolution of plants.Plants have evolved adaptive mechanisms to cope with cold stress.Here,through the genomic analysis of Arabidopsis,three Brassica species and 17 other representative species,we found that both cold-related genes(CRGs)and their collinearity were preferentially retained after polyploidization followed by genome instability,while genome-wide gene sets exhibited a variety of other expansion mechanisms.The coldrelated regulatory network was increased in Brassicaceae genomes,which were recursively affected by polyploidization.By combining our findings regarding the selective retention of CRGs from this ecological genomics study with the available knowledge of cold-induced chromosome doubling,we hypothesize that cold stress may have contributed to the success of polyploid plants through both increasing polyploidization and selectively maintaining CRGs during evolution.This hypothesis requires further biological and ecological exploration to obtain solid supporting evidence,which will potentially contribute to understanding the generation of polyploids and to the field of ecological genomics.

Investigation of Mode Changing,Pulse Nulling and Subpulse Drifting Properties in the Asymmetric Conal Triple Radio Pulsar B2319+60

We report on a detailed analysis of the mode changing,nulling and subpulse drifting behavior of the conal triple pulsar B2319+60 at 1.5 GHz observed with the Nanshan 25 m radio telescope.The pulsar’s profile can be interpreted as resulting from a sightline traverse which cuts across an outer cone and tangentially grazes an inner cone.About 30 per cent of nulls are found to create alternating bunches of nulls and emission in a quasi-periodic manner with an averaged fluctuation rate of about four rotation periods(P_(1)).The presence of two distinct drift modes(A and ABN)plus a phase-stationary non-drift emission mode(B)is confirmed,and each corresponds to a different pulse profile.The mode A is dominated by a phase modulation in the trailing component with a circulation time of around 7P_(1).In addition to a 3P_(1)phase modulation in the leading component,mode ABN presents an amplitude modulation in the leading and trailing components with a period of around 40P_(1).The emission region and geometry remain constant during mode changing.The diversity seen in the individual pulse behavior of the pulsar B2319+60 provides a unique window into the emission physics.

The Chromosome-Based Rubber Tree Genome Provides New Insights into Spurge Genome Evolution and Rubber Biosynthesis

The rubber tree,Hevea brasiliensis,produces natural rubber that serves as an essential industrial raw material.Here,we present a high-quality reference genome for a rubber tree cultivar GT1 using single-molecule real-time sequencing(SMRT)and Hi-C technologies to anchor the～1.47-Gb genome assembly into 18 pseudochromosomes.The chromosome-based genome analysis enabled us to establish a model of spurge chromosome evolution,since the common paleopolyploid event occurred before the split of Hevea and Manihot.We show recent and rapid bursts of the three Hevea-specific LTR-retrotransposon families during the last 10 million years,leading to the massive expansion by～65.88%(～970 Mbp)of the whole rubber tree genome since the divergence from Manihot.We identify large-scale expansion of genes associated with whole rubber biosynthesis processes,such as basal metabolic processes,ethylene biosynthesis,and the activation of polysaccharide and glycoprotein lectin,which are important properties for latex production.A map of genomic variation between the cultivated and wild rubber trees was obtained,which contains～15.7 million high-quality single-nucleotide polymorphisms.We identified hundreds of candidate domestication genes with drastically lowered genomic diversity in the cultivated but not wild rubber trees despite a relatively short domestication history of rubber tree,some of which are involved in rubber biosynthesis.This genome assembly represents key resources for future rubber tree research and breeding,providing novel targets for improving plant biotic and abiotic tolerance and rubber production.

Cut-off values of lesion and vessel quantitative flow ratio in de novo coronary lesion post-drug-coated balloon therapy predicting vessel restenosis at mid-term follow-up

Background:Drug-coated balloons(DCBs)have emerged as potential alternatives to drug-eluting stents in specific lesion subsets for de novo coronary lesions.Quantitative flow ratio(QFR)is a method based on the three-dimensional quantitative coronary angiography and contrast flow velocity during coronary angiography(CAG),obviating the need for an invasive fractional flow reserve procedural.This study aimed to assess the serial angiographic changes of de novo lesions post-DCB therapy and further explore the cut-off values of lesion and vessel QFR,which predict vessel restenosis(diameter stenosis[DS]≥50%)at mid-term follow-up.Methods:The data of patients who underwent DCB therapy between January 2014 and December 2019 from the multicenter hospital were retrospectively collected for QFR analysis.From their QFR performances,which were analyzed by CAG images at follow-up,we divided them into two groups:group A,showing target vessel DS≥50%,and group B,showing target vessel DS<50%.The median follow-up time was 287 days in group A and 227 days in group B.We compared the clinical characteristics,parameters during DCB therapy,and QFR performances,which were analyzed by CAG images between the two groups,in need to explore the cut-off value of lesion/vessel QFR which can predict vessel restenosis.Student's t test was used for the comparison of normally distributed continuous data,Mann-Whitney U test for the comparison of non-normally distributed continuous data,and receiver operating characteristic(ROC)curves for the evaluation of QFR performance which can predict vessel restenosis(DS≥50%)at mid-term follow-up using the area under the curve(AUC).Results:A total of 112 patients with 112 target vessels were enrolled in this study.Group A had 41 patients,while group B had 71.Vessel QFR and lesion QFR were lower in group A than in group B post-DCB therapy,and the cut-off values of lesion QFR and vessel QFR in the ROC analysis to predict target vessel DS≥50%post-DCB therapy were 0.905(AUC,0.741[95%confidence interval,CI:0.645,0.837];sensitivity,0.817;specificity,0.561;P<0.001)and 0.890(AUC,0.796[95%CI:0.709,0.882];sensitivity,0.746;specificity,0.780;P<0.001).Conclusions:The cut-off values of lesion QFR and vessel QFR can assist in predicting the angiographic changes post-DCB therapy.When lesion/vessel QFR values are<0.905/0.890 post-DCB therapy,a higher risk of vessel restenosis is potentially predicted at follow-up.

国际海底区域矿产资源开发环境管理规则制定与应对

随着国际海底区域矿产资源开发日益向现实趋近,国际海底管理局开始制订“区域”矿产资源的开发规章,对“区域”矿产资源开发及相关环境保护要求作出规定。开发规章规定了包括环境管理和监测计划以及环境管理系统在内的环境管理规则。但目前,各国围绕环境管理和监测计划的标准、环境管理系统的内涵、独立专家的权限及其意见的效力、开发活动与海底电缆管道保护的关系仍存在明显的分歧与争议。我国应积极参与开发规章环境管理规则的谈判,提出“中国方案”,主张开发规章应体现《联合国海洋法公约》及其《第十一部分执行协定》的有关规定,实现资源开发利用与生态环境保护之间的合理平衡。