Genomic Signatures of Coevolution between Nonmodel Mammals and Parasitic Roundworms

Antagonistic coevolution between host and parasite drives species evolution. However, most of the studies only focus on parasitism adaptation and do not explore the coevolution mechanisms from the perspective of both host and parasite. Here, through the de novo sequencing and assembly of the genomes of giant panda roundworm, red panda roundworm, and lion roundworm parasitic on tiger, we investigated the genomic mechanisms of coevolution between nonmodel mammals and their parasitic roundworms and those of roundworm parasitism in general. The genome-wide phylogeny revealed that these parasitic roundworms have not phylogenetically coevolved with their hosts. The CTSZ and prolyl 4-hydroxylase subunit beta (P4HB) immunoregulatory proteins played a central role in protein interaction between mammals and parasitic roundworms. The gene tree comparison identified that seven pairs of interactive proteins had consistent phylogenetic topology, suggesting their coevolution during host–parasite interaction. These coevolutionary proteins were particularly relevant to immune response. In addition, we found that the roundworms of both pandas exhibited higher proportions of metallopeptidase genes, and some positively selected genes were highly related to their larvae’s fast development. Our findings provide novel insights into the genetic mechanisms of coevolution between nonmodel mammals and parasites and offer the valuable genomic resources for scientific ascariasis prevention in both pandas.     

中国濒危兽类保护基因组学和宏基因组学研究进展与展望

揭示濒危兽类的演化历史、濒危机制及适应性演化策略,是保护生物学关注的重大科学问题。近十几年来,高通量测序技术的不断发展以及多学科交叉融合,为揭示濒危物种的演化历史、遗传结构、适应性演化及其与肠道微生物的协同演化的分子机制提供了重要的技术支撑,由此产生了保护基因组学和保护宏基因组学两个分支学科,为野生动物尤其是濒危动物的保护生物学研究提供了新的方向与思路。本文综述了我国在保护基因组学和保护宏基因组学领域取得的重要进展,并展望未来的发展趋势,以期进一步推动我国濒危兽类保护生物学的发展。     

阔叶红松林不同演替阶段灌木器官的N、P分配特征

氮（N）、磷（P）是植物生长发育重要的限制元素,N、P以及N、P间的关系是化学计量学研究的重要内容。植物不同器官对N、P的需求存在差异,因此N、P的分配与权衡对植物的生长发育起到重要的调节作用。为了探究阔叶红松（Pinus koraiensis）林不同演替阶段主要灌木器官的N、P化学计量特征及其分配格局,了解灌木的养分限制因子及其分配策略,在黑龙江凉水国家级自然保护区的阔叶红松林四个演替阶段——白桦（Betula platyphylla）次生林、阔叶混交林、针阔混交林和阔叶红松林内,选取主要灌木种,分析了叶片、枝条、茎干和根的N、P化学计量特征以及异速生长关系。结果发现：灌木不同器官之间的N、P含量差异显著,其中叶的N、P含量均为最高,茎干的N、P含量均为最低。所有器官中,叶的N ： P最高,为7.59;根的N ： P最低,为5.47。灌木叶、茎干、根之间的N ： P存在显著差异,而茎干、根与枝条之间的N ： P没有显著差异。阔叶红松林不同演替阶段对灌木同一器官N、P化学计量的影响不同,灌木叶片的N含量在不同演替中具有显著差异,其他器官的差异不显著;不同演替阶段灌木器官的P含量均无显著差异。在不同演替阶段中各器官的N ： P均小于14,说明N元素是阔叶红松林各演替阶段灌木生长的限制因子,而P对灌木的生长没有起到限制作用。研究表明在不同演替阶段中,N、P的异速生长关系普遍存在于灌木器官中,呈现显著的正相关关系;整体上各器官之间的斜率没有显著差异,说明灌木采取保守分配策略,以此来适应环境和满足自身生长发育的需要。     

Study of Oxidative Stress in Human Lens Epithelial Cells Exposed to 1.8 GHz Radiofrequency Fields

Objectives

The aims of the present study were to determine oxidative stress and to explore possible reasons of reactive oxygen species (ROS) increase in human lens epithelial (HLE) B3 cells exposed to low intensity 1.8 GHz radiofrequency fields (RF).

Methods

The HLE B3 cells were divided into RF exposure and RF sham-exposure groups. The RF exposure intensity was at specific absorption rate (SAR) of 2, 3, or 4 W/kg. The ROS levels were measured by a fluorescent probe 2′7′-dichlorofluorescin diacetate (DCFH-DA) assay in the HLE B3 cells exposed to 1.8 GHz RF for 0.5, 1, and 1.5 h. Lipid peroxidation and cellular viability were detected by an MDA test and Cell Counting Kit-8 (CCK-8) assays, respectively, in the HLE B3 cells exposed to 1.8 GHz RF for 6, 12, and 24 h, respectively. The mRNA expression of SOD1, SOD2, CAT, and GPx1 genes and the expression of SOD1, SOD2, CAT, and GPx1 proteins was measured by qRT-PCR and Western blot assays in the HLE B3 cells exposed to 1.8 GHz RF for 1 h.

Results

The ROS and MDA levels significantly increased (P<0.05) in the RF exposure group and that the cellular viability, mRNA expression of four genes, and expression of four proteins significantly decreased (P<0.05) compared with the RF sham-exposure group.

Conclusions

Oxidative stress is present in HLE B3 cells exposed to 1.8 GHz low-intensity RF and that the increased production of ROS may be related to down-regulation of four antioxidant enzyme genes induced by RF exposure.     

Identification of quantitative trait loci for grain size and the contributions of major grain-size QTLs to grain weight in rice

Grain weight, one of the three major components of rice yield, is largely determined by grain size, which is controlled by quantitative trait loci (QTLs). In a previous study, we identified qGS5 as a major QTL for grain width. Here, we report our identification of two more major grain-size QTLs (qGL3 and qGW2a) by using a recombinant inbred line (RIL) population from a cross of two indica varieties, ‘Zhenshan 97’ and ‘SLG’. To investigate the contribution of the three grain-size QTLs to final grain weight, we developed near-isogenic lines (NILs) NIL-qGL3, NIL-qGW2a, and NIL-qGS5 and used these to build the combined QTLs–NIL in the genetic background of ‘Zhenshan 97’ by marker-assisted selection and conventional backcrossing, respectively. A BCF₂ population of 957 individuals was developed from the combined QTLs-NIL for further study of the genetic control of grain size. The QTL analysis revealed that qGW2a and qGL3 played more important roles in grain weight gain than qGS5. All three QTLs showed additive effects with respect to grain weight, with no interaction. These results clearly indicate that pyramiding of major grain-size QTLs is a useful approach for improving rice yield.     

Application of a bacteriophage lysin to disrupt biofilms formed by the animal pathogen Streptococcus suis

Bacterial biofilms are crucial to the pathogenesis of many important infections and are difficult to eradicate. Streptococcus suis is an important pathogen of pigs, and here the biofilm-forming ability of 32 strains of this species was determined. Significant biofilms were completely formed by 10 of the strains after 60 h of incubation, with exopolysaccharide production in the biofilm significantly higher than that in the corresponding planktonic cultures. S. suis strain SS2-4 formed a dense biofilm, as revealed by scanning electron microscopy, and in this state exhibited increased resistance to a number of antibiotics (ampicillin, amoxicillin, ciprofloxacin, kanamycin, and rifampin) compared to that of planktonic cultures. A bacteriophage lysin, designated LySMP, was used to attack biofilms alone and in combination with antibiotics and bacteriophage. The results demonstrated that the biofilms formed by S. suis, especially strains SS2-4 and SS2-H, could be dispersed by LySMP and with >80% removal compared to a biofilm reduction by treatment with either antibiotics or bacteriophage alone of less than 20%; in addition to disruption of the biofilm structure, the S. suis cells themselves were inactivated by LySMP. The efficacy of LySMP was not dose dependent, and in combination with antibiotics, it acted synergistically to maximize dispersal of the S. suis biofilm and inactivate the released cells. These data suggest that bacteriophage lysin could form part of an effective strategy to treat S. suis infections and represents a new class of antibiofilm agents.     

内蒙古不同类型草地叶面积指数遥感估算

叶面积指数(Leaf Area Index,LAI)是重要的植被结构参数,反演LAI是植被遥感的重要研究内容之一。根据在内蒙古呼伦贝尔和锡林浩特草原利用LAI 2000观测的草地LAI,比较了不同植被指数(SR、RSR、EVI、NDVI、SAVI和ARVI)估算不同类型草地LAI的能力,建立了基于Landsat-5 TM遥感数据的LAI估算模型,并利用LAI观测数据对模型进行了检验,生成了研究区内草地LAI分布图,据此对MODIS LAI产品一致性进行了评价。结果表明,在呼伦贝尔和锡林浩特两个研究区,RSR与LAI的相关性最高(R²分别为0.628、0.728,RMSE分别为0.512、0.490),在低密度草地,RSR的优势更为明显;验证表明,根据RSR建立的LAI估算模型的精度可达70%;利用TM数据生成的两个地区的LAI(TM LAI)空间变化明显,锡林浩特草地的LAI值整体上低于呼伦贝尔草地;在呼伦贝尔和锡林浩特,MODIS LAI产品与TM LAI一致性分别为0.566,0.323,MODIS LAI产品高估了呼伦贝尔草地LAI值,而在锡林浩特研究区则存在低估现象。     

Mixed bumblebee and blowfly pollination of Cypripedium flavum (Orchidaceae) in Sichuan,China

Most Cypripedium species are specialized orchids pollinated by, in a broad sense, bees or flies. Here we present the first evidence that a slipper orchid, Cypripedium flavum, is pollinated by both bees and flies, i.e., bumblebees and blowflies. Artificial pollination experiments demonstrated that the flowers of C. flavum are self-compatible, but need pollen vectors for successful reproduction. Field observations detected 25 insects visiting the flowers, and 14 of these insects entered into the labellum of the flowers, but only female bumblebees, Bombus hypnorum, B. remotus, and the blowfly Calliphora vomitoria exited of the labellum with pollen smears of C. flavum. The floral functional morphology of C. flavum appears to be more suited to bumblebees than to blowflies. The bumblebees are more efficient pollinators of the orchid, but blowflies are more frequent visitors, so they pollinated more flowers despite being less efficient.