摘要：
The evolution of floral traits has been thought to be influenced by local,effective pollinators.However,little attention has been paid to the possibility that altitudinal variation in floral traits could be mediated by local pollinator functional groups,particularly a shift from bees to birds.Plant size,floral traits,pollinators and their pollination roles were investigated in the spring-flowering shrub Elaeagnus umbellata (Elaeagnaceae) at three altitudes (1160,1676,and 2050 m) in Minshan,Sichuan Province,on the northern rim of the Hengduan Mountains,southwest China.Compared to lower altitudes,higher-altitude plants were smaller but the floral tubes were longer,with a larger volume of nectar of lower sugar concentration but with a greater proportion of sucrose.The visitation frequency of bees decreased with altitude,whereas the sunbirds did the opposite.Birds and bees foraged for nectar but not pollen,and birds deposited more pollen grains per visit relative to bees and least were syrphid flies.Excluding birds decreased seed set at high but not at mid-or low altitude.Our study of E.umbellata revealed an association between altitudinal variation in floral traits and a change in the relative abundance of the major pollinators with altitude from majority bees to majority sunbirds.Although abiotic factors also tend to vary with altitude and can affect floral traits,nectar properties of "pro-bird" pollination were observed at high altitude.
摘要：
Bacteria growth depends crucially on protein synthesis, which is limited by ribosome synthesis. Ribosomal RNA (rRNA) transcription is the rate-limiting step of ribosome synthesis. It is generally proposed that the transcriptional initiation rate of rRNA operon is the primary factor that controls the rRNA synthesis. In this study, we established a convenient GFP-based reporter approach for measuring the bacterial rRNA chain elongation rate. We showed that the rRNA chain elongation rate of Escherichia coli remains constant under nutrient limitation and chloramphenicol inhibition. In contrast, rRNA chain elongation rate decreases dramatically under low temperatures. Strikingly, we found that Vibrio natriegens, the fastest growing bacteria known, has a 50% higher rRNA chain elongation rate than E. coli, which contributes to its rapid ribosome synthesis. Our study demonstrates that rRNA chain elongation rate is another important factor that affects the bacterial ribosome synthesis capacity.
作者机构：
[Yong, Yu-Le; Lin, Peng; Liu, Man; Zheng, Nai-Shan; Li, Hao; Zhang, Ren-Yu; Chen, Zhi-Nan; Bian, Huijie; Liu, Ze-Kun; Wei, Ding] Fourth Mil Med Univ, Natl Translat Sci Ctr Mol Med, Dept Cell Biol, Xian 710032, Peoples R China.;[Liu, Ke] Cent China Normal Univ, Sch Life Sci, Wuhan 430079, Peoples R China.;[Yang, Xiao-Zhen; Hu, Cai-Xia] Capital Med Univ, Beijing Youan Hosp, Oncol & Hepatobiliary Minimally Invas Intervent C, Beijing 100069, Peoples R China.
通讯机构：
[Chen, ZN; Bian, HJ] F;Fourth Mil Med Univ, Natl Translat Sci Ctr Mol Med, Dept Cell Biol, Xian 710032, Peoples R China.
摘要：
Genomic sequencing analysis of tumors provides potential molecular therapeutic targets for precision medicine. However, identifying a key driver gene or mutation that can be used for hepatocellular carcinoma (HCC) treatment remains difficult. Here, we performed whole-exome sequencing on genomic DNA obtained from six pairs of HCC and adjacent tissues and identified two novel somatic mutations of UBE2S (p. Gly57Ala and p. Lys63Asn). Predictions of the functional effects of the mutations showed that two amino-acid substitutions were potentially deleterious. Further, we observed that wild-type UBE2S, especially in the nucleus, was significantly higher in HCC tissues than that in adjacent tissues and closely related to the clinicopathological features of patients with HCC. Functional assays revealed that overexpression of UBE2S promoted the proliferation, invasion, metastasis, and G1/S phase transition of HCC cells in vitro, and promoted the tumor growth significantly in vivo. Mechanistically, UBE2S interacted with TRIM28 in the nucleus, both together enhanced the ubiquitination of p27 to facilitate its degradation and cell cycle progression. Most importantly, the small-molecule cephalomannine was found by a luciferase-based sensitive high-throughput screen (HTS) to inhibit UBE2S expression and significantly attenuate HCC progression in vitro and in vivo, which may represent a promising strategy for HCC therapy.
摘要：
With the increase in the need for flood prevention and lake resource used by humans, the construction of floodgates and sluices has changed the hydrological connection between rivers and lakes, and between adjacent lakes. In river-disconnected lakes, exploitation and use of lake resources have resulted in water quality decline and mechanical disturbance intensification to a different degree. Of the large number of river-disconnected lakes in the middle-lower reaches of the Changjiang (Yangtze) River, the Futou Lake, and the Xiliang Lake lie close together and are, historically, directly connected, and so do Liangzi Lake and Baoan Lake. The extent of human disturbance is severe in the Futou Lake and the Baoan Lake, but relatively mild in the Xiliang Lake and Liangzi Lake. The freshwater rosette-forming submerged plant Vallisneria natans is one of the dominant species in the four lakes. Using microsatellite markers, we studied the genetic variation of V. natans subpopulations in lakes with different intensities of human disturbance and historical direct hydrological connections. Our results showed that human disturbance decreased plant density and clonal growth in V. natans, but might increase genetic and clonal diversity at a subpopulation level and enhance gene flow among subpopulations by sexual propagule movement. Under similar climatic conditions, different intensities of disturbance seem to have such a high selective potential to differentiate genetically adjacent lake populations that they outperform the forces of gene flow through historical direct hydrological interconnection, which tends to produce genetic homogeneity. Our findings imply that human disturbance has a profound effect on the evolutionary process of natural populations of submerged plants. Moreover, increased subpopulation genetic diversity can enhance resistance and resilience to environmental disturbances. To a certain degree, we could expect that disturbed populations have the possibility of restoring spontaneously if humans cease to perturb natural ecosystems in the future.
作者机构：
[Zhang, Zhibin] Chinese Acad Sci, Inst Zool, State Key Lab Integrated Management Pest Insects, Beijing, Peoples R China.;[Zhang, Zhibin] Univ Chinese Acad Sci, CAS Ctr Excellence Biot Interact, Beijing, Peoples R China.;[Yan, Chuan] Lanzhou Univ, Inst Innovat Ecol, State Key Lab Grassland Agroecosyst, Lanzhou, Peoples R China.;[Yan, Chuan] Lanzhou Univ, Coll Life Sci, Lanzhou, Peoples R China.;[Zhang, Hongmao] Cent China Normal Univ, Inst Evolut & Ecol, Sch Life Sci, Wuhan, Peoples R China.
作者机构：
[Luo, Tao; Zhou, Jiang; Wen, Huamei; Zhou, Jun] Guizhou Normal Univ, Sch Karst Sci, Guiyang 550001, Guizhou, Peoples R China.;[Wen, Huamei] Cent China Normal Univ, Sch Life Sci, Wuhan 430000, Hubei, Peoples R China.;[Gao, Kai] Beijing Normal Univ, Coll Life Sci, Minist Educ, Key Lab Biodivers & Ecol Engn, Beijing 100875, Peoples R China.
通讯机构：
[Zhou, Jiang] G;Guizhou Normal Univ, Sch Karst Sci, Guiyang 550001, Guizhou, Peoples R China.
关键词：
Biogeography;Cryptic diversity;Guizhou;P. caudopunctatus species group;Phylogeography;Species delimitation
摘要：
The Paramesotriton caudopunctatus species group is mainly distributed in the karst mountain ecosystems of Guizhou, China. Although some species have been included in previous phylogenetic studies, the evolutionary relationships and divergence-time of members of this species group as a whole remain unexplored. In this study, we report the sequencing of one protein coding mitochondrial gene fragment（ND2） and one nuclear gene（POMC）, and use a combination of phylogenetic analyses and coalescent simulations to explore the cryptic diversity and evolutionary history of the P. caudopunctatus species group. Phylogenetic relationships revealed that the P. caudopunctatus species group is composed of two major groups, i. e., East Clade and Western-South Clade. The divergence-time and ancestral area estimation suggested that the P. caudopunctatus species group likely originated in the Doupeng Mountains in Guizhou, China at 12.34 Ma（95% HPD: 8.30–14.73）, and intraspecific divergence began at about 2.17 Ma（95% HPD: 1.39–2.97）. This timing coincides with the orogenesis of the Miaoling Mountains during the Late Miocene to early Pleistocene. The delimitation of species in the P. caudopunctatus species group supports the existence of the currently identified species, and consensus was confirmed across methods for the existence of least to two cryptic species within what has been traditionally considered to be P. caudopunctatus species group. This study is of significance for understanding the species formation, dispersal, and diversity of the tailed amphibians in the karst mountains ecosystem of Guizhou and the role of the Miaoling Mountains as a geographical barrier to species dispersal.
