Flight loss linked to faster molecular evolution in insects

The loss of flight ability has occurred thousands of times independently during insect evolution. Flight loss may be linked to higher molecular evolutionary rates because of reductions in effective population sizes (N_e) and relaxed selective constraints. Reduced dispersal ability increases population subdivision, may decrease geographical range size and increases (sub)population extinction risk, thus leading to an expected reduction in N_e. Additionally, flight loss in birds has been linked to higher molecular rates of energy-related genes, probably owing to relaxed selective constraints on energy metabolism. We tested for an association between insect flight loss and molecular rates through comparative analysis in 49 phylogenetically independent transitions spanning multiple taxa, including moths, flies, beetles, mayflies, stick insects, stoneflies, scorpionflies and caddisflies, using available nuclear and mitochondrial protein-coding DNA sequences. We estimated the rate of molecular evolution of flightless (FL) and related flight-capable lineages by ratios of non-synonymous-to-synonymous substitutions (dN/dS) and overall substitution rates (OSRs). Across multiple instances of flight loss, we show a significant pattern of higher dN/dS ratios and OSRs in FL lineages in mitochondrial but not nuclear genes. These patterns may be explained by relaxed selective constraints in FL ectotherms relating to energy metabolism, possibly in combination with reduced N_e.     

Heritabilities,social environment effects and genetic correlations of social behaviours in a cooperatively breeding vertebrate

Social animals interact frequently with conspecifics, and their behaviour is influenced by social context, environmental cues and the behaviours of interaction partners, allowing for adaptive, flexible adjustments to social encounters. This flexibility can be limited by part of the behavioural variation being genetically determined. Furthermore, behaviours can be genetically correlated, potentially constraining independent evolution. Understanding social behaviour thus requires carefully disentangling genetic, environmental, maternal and social sources of variations as well as the correlation structure between behaviours. Here, we assessed heritability, maternal, common environment and social effects of eight social behaviours in Neolamprologus pulcher, a cooperatively breeding cichlid. We bred wild‐caught fish in a paternal half‐sibling design and scored ability to defend a resource against conspecifics, to integrate into a group and the propensity to help defending the group territory (“helping behaviour”). We assessed genetic, social and phenotypic correlations within clusters of behaviours predicted to be functionally related, namely “competition,” “aggression,” “aggression‐sociability,” “integration” and “integration‐help.” Helping behaviour and two affiliative behaviours were heritable, whereas there was little evidence for a genetic basis in all other traits. Phenotypic social effects explained part of the variation in a sociable and a submissive behaviour, but there were no maternal or common environment effects. Genetic and phenotypic correlation within clusters was mostly positive. A group's social environment influenced covariances of social behaviours. Genetic correlations were similar in magnitude but usually exceeding the phenotypic ones, indicating that conclusions about the evolution of social behaviours in this species could be provisionally drawn from phenotypic data in cases where data for genetic analyses are unobtainable.     

重度抑郁症患者血清CXCL1、CCL11水平与生活事件和自杀意念的关系研究

摘要 目的：探讨重度抑郁症（MDD）患者血清CXC趋化因子配体1（CXCL1）、CC趋化因子11（CCL11）水平与生活事件和自杀意念的关系。方法：选取2020年1月-2021年6月我院收治的MDD患者100例作为病例组,选取同期100例健康体检的志愿者作为对照组,比较两组研究对象的血清CXCL1、CCL11水平、生活事件量表（LES）评定结果,采用Pearson法分析LES评定结果与CXCL1、CCL11水平的相关性。100例MDD患者根据有无自杀意念,分为自杀意念组（n=45）和无自杀意念组（n=55）,采用单因素及多因素Logistic回归分析MDD患者自杀意念相关影响因素。结果：病例组患者血清CXCL1、CCL11水平,负性事件刺激量、生活事件应激总分高于对照组（P＜0.05）,正性事件刺激量低于对照组（P＜0.05）;血清CXCL1、CCL11水平与负性事件刺激量呈正相关（P＜0.05）;本研究调查结果显示,MDD患者调查期间自杀意念发生率为45.00%,自杀意念组患者性别、自杀未遂史、病程、合并焦虑症状、精神质、神经质、内外向、掩饰性、CXCL1、CCL11、负性事件刺激量、生活事件应激总分与无自杀意念组比较差异有统计学意义（P＜0.05）,多因素Logistic回归分析结果显示,性别、精神质、神经质,血清CXCL1、CCL11水平,负性事件刺激量是MDD患者自杀意念发生的影响因素。结论：MDD患者血清CXCL1、CCL11水平升高,血清CXCL1、CCL11水平与负性事件刺激量存在一定的相关性,MDD患者出现自杀意念的概率较高,且血清CXCL1、CCL11水平及负性事件刺激量等均是其自杀意念发生的影响因素,临床工作中应针对相关影响因素积极采取应对措施。     

早期心电图QRS 波宽度对急性ST 段抬高型心肌梗死患者心脏不良事件的影响

目的:探讨早期心电图QRS波宽度(QRSw)对急性ST段抬高型心肌梗死(STEMI)患者近期主要心脏不良事件(MACE)的影响。方法:选取我院收治的135例STEMI患者为研究对象,按照入院时的心电图QRSw将患者分为A组(QRSw为60 ms≤QRSw≤80 ms)、B组(QRSw为80 msQRSw100 ms)、C组(QRSw为QRSw≥100 ms),将是否发生MACE分为MACE组和非MACE组,比较各组相关指标的差异,分析QRSw与MACE发生的关系。结果:A、B及C组三组患者在梗死面积、肌酸激酶同工酶(CK-MB)、肌钙蛋白I(c Tn I)、B型脑钠肽(BNP)、高敏C反应蛋白(hs-CRP)、左室射血分数(LVEF)方面存在显著的统计学差异(P0.05),与A组及B组比较,C组血清hs-CRP、BNP、c Tn I、CK-MB较高,梗死面积大、LVEF偏低。三组患者在MACE发生率方面亦存在显著的统计学差异(P0.05),C组高于A组及B组。MACE组患者QRSw高于非MACE组(P0.05),其含有QRSw≥100 ms患者的比例亦高于非MACE组(P0.05);QRSw(OR=1.214,CI:1.104~1.441,P0.05)是STEMI患者近期MACE发生的独立危险因素。结论:STEMI患者随着QRSw增大,MACE的发生风险亦增加,QRSw可能是STEMI患者近期MACE发生的独立危险因素,应当引起临床重视。     

霍乱弧菌EL－Tor35A3菌株外膜蛋白主区带的纯化

选用霍乱弧菌ＥＬ－Ｔｏｒ生物型３５Ａ３菌株（血清稻叶型）以ＥＤＴＡ－溶菌酶法与超速离心法提取其外膜蛋白,并将聚丙烯酰胺凝胶电泳后一条蛋白主区带分离。ＳＤＳ－聚丙烯酰胺凝胶电泳测得该蛋白主区带的分子量为２５ｋＤ,免疫电泳显示一条线,免疫双扩试验表明,不同的霍乱弧菌菌株均有该蛋白抗原存在。     

Immunogenicity of a non-class I MHC expressing murine tumor transfected with the influenza virus hemagglutinin or murine interleukin-2 genes

Summary The transfection of murine SP1 tumor cells with the hemagglutinin (HA) gene of influenza virus results, after fluorescent-activated cell sorting (FACS), in the selection of high-HA-expressing cell lines called H4A and H4B. Both lines fail to grow in syngeneic animals at doses that result in 100% tumor take of non-transfected tumor cells. Both grow in immunosuppressed mice. SP1 and H4A or H4B cells express few class I major histocompatibility complex (MHC) antigens but do express class II IA^k antigens. H4A or H4B cells engender a cytotoxic T lymphocyte (CTL) response but cannot protect against a challenge with SP1 cells. This CTL response is inhibited by anti-CD4 but not anti-CD8 antibodies. Using FACS, we were able to select a population (called H5AK5) with high class-I MHC antigen expression. Like H4A and H4B, H5AK5 cells fail to grow in syngeneic animals but do grow in immunosuppressed mice. However, unlike H4A or H4B, H5AK5 can induce protection against a challenge with 1 × 10⁵ SP1 cells. These studies indicate that the immunogenicity ofHA-transfected SP1 cells may correlate with the cell-surface expression of class II MHC antigens. However, HA-expressing SP1 cells seem able to induce a protective response against a parent SP1 cell challenge only if they also express class I MHC antigens. This view is supported by the observations that SP1 cells expressing murine interleukin-2 do not express class I MHC antigens, fail to grow in syngeneic animals, do grow in immunosuppressed mice but do not protect against a challenge with parental SP1 cells.This work was supported by The Clayton Fund, The Sid W. Richardson Foundation and PHS grants CA 39853 and 41525. Toshiyuki Itaya is a visiting scientist supported by the Smith Education Fund of the Department of Cell Biology. Troy Fiesinger is a summer research investigator sponsored by The University of Texas M. D. Anderson Cancer Center Summer Program for College Students     

Directional mutation pressure,mutator mutations,and dynamics of molecular evolution

Using a general form of the directional mutation theory, this paper analyzes the effect of mutations in mutator genes on the G + C content of DNA, the frequency of substitution mutations, and evolutionary changes (cumulative mutations) under various degrees of selective constraints. Directional mutation theory predicts that when the mutational bias between A/T and G/C nucleotide pairs is equilibrated with the base composition of a neutral set of DNA nucleotides, the mutation frequency per gene will be much lower than the frequency immediately after the mutator mutation takes place. This prediction explains the wide variation of the DNA G + C content among unicellular organisms and possibly also the wide intragenomic heterogeneity of third codon positions for the genes of multicellular eukaryotes. The present analyses lead to several predictions that are not consistent with a number of the frequently held assumptions in the field of molecular evolution, including belief in a constant rate of evolution, symmetric branching of phylogenetic trees, the generality of higher mutation frequency for neutral sets of nucleotides, the notion that mutator mutations are generally deleterious because of their high mutation rates, and teleological explanations of DNA base composition. Presented at the NATO Advanced Research Workshop onGenome Organization and Evolution, Spetsai, Greece, 16–22 September 1992     

Functional constraints on nest characteristics of pebble mounds of breeding male hornyhead chub Nocomis biguttatus

Breeding male hornyhead chub Nocomis biguttatus constructed nests in areas with relatively high but less than maximum flow rate and greater than average water depth. Nests comprised c. 3000 pebbles for a total mass of 11 kg. Males selected pebbles of smaller diameter but higher density than pebbles in the immediate vicinity. Thus, nests balanced the risk of mound erosion and energetic cost of nest construction with the benefits of protection from egg predators and a stable internal flow rate for oxygenation. These data help establish environmental management goals for the conservation of N. biguttatus and the lotic ecosystems dependent upon them.     

Patterns of genetic variation and covariation in ejaculate traits reveal potential evolutionary constraints in guppies

Ejaculates comprise multiple and potentially interacting traits that determine male fertility and sperm competitiveness. Consequently, selection on these traits is likely to be intense, but the efficacy of selection will depend critically on patterns of genetic variation and covariation underlying their expression. In this study, I provide a prospective quantitative genetic analysis of ejaculate traits in the guppy Poecilia reticulata, a highly promiscuous live-bearing fish. I used a standard paternal half-sibling breeding design to characterize patterns of genetic (co)variation in components of sperm length and in vitro sperm performance. All traits exhibited high levels of phenotypic and additive genetic variation, and in several cases, patterns of genetic variation was consistent with Y-linkage. There were also highly significant negative genetic correlations between the various measures of sperm length and sperm performance. In particular, the length of the sperm's midpiece was strongly, negatively and genetically correlated with sperm's swimming velocity-an important determinant of sperm competitiveness in this and other species. Other components of sperm length, including the flagellum and head, were independently and negatively genetically correlated with the proportion of live sperm in the ejaculate (sperm viability). Whether these relationships represent evolutionary trade-offs depends on the precise relationships between these traits and competitive fertilization rates, which have yet to be fully resolved in this (and indeed most) species. Nevertheless, these prospective analyses point to potential constraints on ejaculate evolution and may explain the high level of phenotypic variability in ejaculate traits in this species.