马铃薯甲虫结节性硬化复合物基因LdTSC1和LdTSC2基因的克隆及功能分析

【目的】通过RNAi技术明确马铃薯甲虫TOR上游的关键信号集成节点及类胰岛素信号通道下游基因结节性硬化复合物TSC1和TSC2的功能。旨在为探明马铃薯甲虫类胰岛素信号转导提供更多理论支持。【方法】在NCBI(美国国家生物技术信息中心)获取马铃薯甲虫LdTSC1/2序列,分别利用多重序列比对和系统发育分析确定该基因的完整性和系统发育关系;采用喂食幼虫dsRNA的方法,观察该基因的调低对马铃薯甲虫幼虫生长发育、糖脂代谢的影响。【结果】克隆得到马铃薯甲虫TSC1编码蛋白的氨基酸序列与鞘翅目白蜡窄吉丁直系同源蛋白的氨基酸序列的自展一致度为100%,聚为一支;TSC2编码蛋白的氨基酸序列与鞘翅目白蜡窄吉丁和赤拟谷盗的同源蛋白氨基酸序列的自展一致度为100%,聚为一支。通过分别喂食2龄幼虫LdTSC1/2的dsRNA能有效降低靶标基因的表达量,幼虫出现体重减轻,化蛹率和羽化率显著下降,葡萄糖的吸收转化效率降低,海藻糖含量升高和甘油三酯均减少。【结论】下调2龄幼虫LdTSC1/2的表达量,导致试虫出现抑制了糖脂代谢、脂肪体减少、体重减轻以及发育延迟;结果表明LdTSC1/2调控了马铃薯甲虫幼虫的糖脂代谢过程,显著影响幼虫化蛹和蜕皮过程。     

Clinical features and hematological findings of COVID-19 patients with blood transfusion

This paper aims to illustrate the clinical characteristics, hematological findings, and blood transfusion information of Coronavirus disease 2019 (COVID-19) patients. Twenty-three COVID-19 patients were treated and transfused with blood products in Wuhan First Hospital from February 12 to March 20, 2020. The patients were divided into a survivor group and a non-survivor group, respectively, according to whether the patient had been discharged or died. The results demonstrated at the time of initial blood transfusion, that the non-survivor group possessed a lower platelet (PLT) than that of the survivor group (P<0.001), and PLT were below the normal range in 6 (85.7%) non-survivor group and in 2 (12.5%) survivor group (P<0.01). Over half of these patients had abnormalities in fibrinogen (FIB), activated partial thromboplastin time (APTT), prothrombin time (PT), and international normalized ratio (INR), but no significant difference was found between the non-survivor group and survivor group. The non-survivor group had a dramatically higher D-Dimers and disseminated intravascular coagulation (DIC) scores than those of the survivor group (P<0.01). Six (85.7%) non-survivors but none of the survivors had a DIC score greater than 6 (P<0.001). Fifteen (93.8%) survivors and 2 (28.6%) non-survivors were transfused with RBC (P<0.01). The non-survivors (5/7) possessed a higher proportion for using AP than the survivors (2/16). The study suggests that COVID-19 patients who undergo blood transfusion usually possess coagulation dysfunction, and DIC may be closely related to deteriorating clinical outcomes.     

The complete chloroplast genome of Myriophyllum spicatum reveals a 4‐kb inversion and new insights regarding plastome evolution in Haloragaceae

Myriophyllum, among the most species‐rich genera of aquatic angiosperms with ca. 68 species, is an extensively distributed hydrophyte lineage in the cosmopolitan family Haloragaceae. The chloroplast (cp) genome is useful in the study of genetic evolution, phylogenetic analysis, and molecular dating of controversial taxa. Here, we sequenced and assembled the whole chloroplast genome of Myriophyllum spicatum L. and compared it to other species in the order Saxifragales. The complete chloroplast genome sequence of M. spicatum is 158,858 bp long and displays a quadripartite structure with two inverted repeats (IR) separating the large single copy (LSC) region from the small single copy (SSC) region. Based on sequence identification and the phylogenetic analysis, a 4‐kb phylogenetically informative inversion between trnE‐trnC in Myriophyllum was determined, and we have placed this inversion on a lineage specific to Myriophyllum and its close relatives. The divergence time estimation suggested that the trnE‐trnC inversion possibly occurred between the upper Cretaceous (72.54 MYA) and middle Eocene (47.28 MYA) before the divergence of Myriophyllum from its most recent common ancestor. The unique 4‐kb inversion might be caused by an occurrence of nonrandom recombination associated with climate changes around the K‐Pg boundary, making it interesting for future evolutionary investigations.     

DNA methylation and demethylation link the properties of mesenchymal stem cells: Regeneration and immunomodulation

Mesenchymal stem cells (MSCs) are a heterogeneous population that can be isolated from various tissues, including bone marrow, adipose tissue, umbilical cord blood, and craniofacial tissue. MSCs have attracted increasingly more attention over the years due to their regenerative capacity and function in immunomodulation. The foundation of tissue regeneration is the potential of cells to differentiate into multiple cell lineages and give rise to multiple tissue types. In addition,the immunoregulatory function of MSCs has provided insights into therapeutic treatments for immune-mediated diseases. DNA methylation and demethylation are important epigenetic mechanisms that have been shown to modulate embryonic stem cell maintenance, proliferation, differentiation and apoptosis by activating or suppressing a number of genes. In most studies, DNA hypermethylation is associated with gene suppression, while hypomethylation or demethylation is associated with gene activation. The dynamic balance of DNA methylation and demethylation is required for normal mammalian development and inhibits the onset of abnormal phenotypes. However, the exact role of DNA methylation and demethylation in MSC-based tissue regeneration and immunomodulation requires further investigation. In this review, we discuss how DNA methylation and demethylation function in multi-lineage cell differentiation and immunomodulation of MSCs based on previously published work. Furthermore, we discuss the implications of the role of DNA methylation and demethylation in MSCs for the treatment of metabolic or immune-related diseases.     

Migration sources and pathways of the pest species Sogatella furcifera in Yunnan,China, and across the border inferred from DNA and wind analyses

The migration sources and pathways of Sogatella furcifera (Horváth) in topologically complex regions like Yunnan, China, and adjacent montane areas have long been a challenging task and a bottleneck in effective pest forecast and control. The present research reinvestigated this issue using a combination of mtDNA and long‐term historical wind field data in an attempt to provide new insights. Genetic analyses showed that the 60 populations of S. furcufera collected across Myanmar, Thailand, Laos, Vietnam, Yunnan, Guizhou, and Sichuan lack genetic structure and geographic isolation, while spatial analysis of haplotype and diversity indices discovered geographic relevance between populations. Migration rate analysis combined with high‐resolution 10‐year wind field analysis detected the following migration sources, pathways, and impacted areas which could explain the outbreak pattern in Yunnan. (a) Dominating stepwise northward migrations originated from northern Indochina, southern Yunnan, and central‐eastern Yunnan, impacting their northern areas. (b) Concurring summer–autumn southward (return) migration originated from nearly all latitude belts of Sichuan and Yunnan mainly impacting central and southern Yunnan. (c) Regular eastward and summer–autumn westward migrations across Yunnan. The northward migration reflects the temporal rhythm of gradual outbreaks from the south to the north in a year, while the return migration may explain the repeated or very severe outbreaks in the impacted areas. To form a better pest forecast and control network, attention must also be paid to the northern part of Yunnan to suppress the impact of return migration in summers and autumns.     

Priority effects and competition by a native species inhibit an invasive species and may assist restoration

Selecting native species for restoration is often done without proper ecological background, particularly with regard to how native and invasive species interact. Here, we provide insights suggesting that such information may greatly enhance restoration success. The performance of the native vine, Pueraria lobata, and that of the invasive bitter vine, Mikania micrantha, were investigated in South China to test how priority effects (timing and rate of germination and seedling growth) and competition (phytochemical effects and competitive ability) impact invasive plant performance. We found that, in the absence of competition, the germination rate of M. micrantha, but not of P. lobata, was significantly affected by light availability. P. lobata seedlings also performed better than those of M. micrantha during early growth phases. Under competition, negative phytochemical effects of P. lobata on M. micrantha were strong and we found M. micrantha to have lower performance when grown with P. lobata compared to when grown by itself. Relative interaction indexes indicated that, under interspecific competition, P. lobata negatively affected (i.e., inhibited) M. micrantha, whereas M. micrantha positively affected (i.e., facilitated) P. lobata. Higher photosynthetic efficiency and soil nutrient utilization put P. lobata at a further advantage over M. micrantha. Field trails corroborated these experimental findings, showing little recruitment of M. micrantha in previously invaded and cleared field plots that were sown with P. lobata. Thus, P. lobata is a promising candidate for ecological restoration and for reducing impacts of M. micrantha in China. This research illustrates that careful species selection may improve restoration outcomes, a finding that may also apply to other invaded ecosystems and species.     

The effect of grazing on winter survival of midday gerbil (Meriones meridianus) of different genders

The objective of this study was to investigate the effects of grazing on midday gerbil (Meriones meridianus) population characteristics and survival of animals of different genders. The experiment used a randomized complete block design and was conducted in Alxa Left Banner, Inner Mongolia, China, in 2002 (The agricultural reclamation plots set up in 1994). From April 2006 to October 2010, midday gerbils were live‐trapped in 3 light grazing plots, 3 overgrazed plots, and 3 grazing exclusion plots. The quantity of vegetation was investigated in the two different grazing intensity areas and grazing exclusion area to determine the relationship between gerbils and plant food availability. The results suggested that there was higher gerbil density, individual body mass, and daily body mass growth rate in the grazing exclusion sites than the other sites across the whole year. Females had higher survival in grazing exclusion areas than in other treatments, but the males’ survival showed the opposite pattern. Our results indicated that grazing negatively influenced the midday gerbil population by reducing food availability. Grazing influenced the survival rates of male midday gerbils positively, but had negative effects on females. The reason for gendered differences in survival rates of midday gerbils requires further investigation.     

Physiological and metabolomic responses of bermudagrass (Cynodon dactylon) to alkali stress

Bermudagrass (Cynodon dactylon) is a widely used warm‐season turfgrass species with superior stress tolerance except for cold. In this study, a comparative analysis of the responses to alkali stress in bermudagrass at the physiological and metabolomic levels were performed. Mild alkali with relatively low pH slightly inhibited growth of bermudagrass as evidenced by lower electrolyte leakage, more rapid growth and higher survival rate when compared to moderate and severe alkali treatments. Moreover, the amount of 37 metabolites including amino acids, organic acids, sugars and sugar alcohols were modulated by the alkali treatments. Among them, 15 metabolites were involved in carbon and amino acid metabolic pathways. Under mild alkali stress, bermudagrass possibly slowed down metabolisms to maintain basic growth. However, moderate and severe alkali‐stressed plants accumulated significantly higher amount of carbohydrates which might result in carbon starvation. Taken together, alkali stress had severely inhibitory effect partially due to combined ionic stress and high pH stress. These results suggested that bermudagrass employed different strategies in response to alkali stresses with different pH and ionic values.     

An Efficient Plant Regeneration System of <i>Hydrangea bretschneideri</i> Dipp via Stem Segments as Explants

Hydrangea bretschneideri Dipp is a highly popular ornamental plant for garden decoration. Genetic engineering technology has been successfully used in many plant species, but it is limited in Hydrangea. Here we established an efficient regeneration system by using stem segments as explants for the first time. In our study, the plant growth regulators (PGRs) were evaluated at the different regeneration processes, including axillary shoots regeneration and root induction. We found that the optimal concentration for axillary buds’ induction was 2.0 mgL⁻¹ 6-BA and 0.5 mgL⁻¹ 1 IAA, its highest induction rate was 70%. Moreover, the highest axillary shoots proliferation coefficient was 10.7 on the Murashige and Skoog (MS) medium with 2.0 mgL⁻¹ 6-benzyladenine (BA), 0.2 mgL⁻¹ indole-3-butyric acid (IBA), and 1.0 mgL⁻¹ gibberellin A3 (GA3). The highest frequency of root induction was 80.0 ± 0.06% by culturing the elongated shoots in 1/2 MS medium containing 0.1 mgL⁻¹ IBA. In summary, our study will provide an effective technology for large-scale propagation and important pathway for promoting the popularization and application of Hydrangea bretschneideri Dipp.