Evaluating human autosomal loci for sexually antagonistic viability selection in two large biobanks

Sex and sexual differentiation are pervasive across the tree of life. Because females and males often have substantially different functional requirements, we expect selection to differ between the sexes. Recent studies in diverse species, including humans, suggest that sexually antagonistic viability selection creates allele frequency differences between the sexes at many different loci. However, theory and population-level simulations indicate that sex-specific differences in viability would need to be very large to produce and maintain reported levels of between-sex allelic differentiation. We address this contradiction between theoretical predictions and empirical observations by evaluating evidence for sexually antagonistic viability selection on autosomal loci in humans using the largest cohort to date (UK Biobank, n = 487,999) along with a second large, independent cohort (BioVU, n = 93,864). We performed association tests between genetically ascertained sex and autosomal loci. Although we found dozens of genome-wide significant associations, none replicated across cohorts. Moreover, closer inspection revealed that all associations are likely due to cross-hybridization with sex chromosome regions during genotyping. We report loci with potential for mis-hybridization found on commonly used genotyping platforms that should be carefully considered in future genetic studies of sex-specific differences. Despite being well powered to detect allele frequency differences of up to 0.8% between the sexes, we do not detect clear evidence for this signature of sexually antagonistic viability selection on autosomal variation. These findings suggest a lack of strong ongoing sexually antagonistic viability selection acting on single locus autosomal variation in humans.     

呼吸道感染患者多重耐药菌肺炎克雷伯菌的耐药及危险因素分析

摘要 目的：探讨与分析呼吸道感染患者多重耐药菌肺炎克雷伯菌的耐药及危险因素。方法：选择2015年1月到2020年2月本院诊治的呼吸道感染患者65例作为研究对象,收集患者的临床样本进行细菌分离与耐药分析,调查患者的临床资料并进行危险因素分析。结果：在呼吸道感染患者65例中,分离出多重耐药菌肺炎克雷伯菌32株,占比49.2 %,其中下呼吸道、上呼吸道、灌洗液、血液标本分别占50.0 %、9.4 %、25.0 %、6.3 %。32株多重耐药菌肺炎克雷伯菌对头孢曲松、头孢呋辛、氨苄西林、头孢吡肟、头孢噻肟的耐药率分别为71.9 %、87.5 %、96.9 %、84.4 %、81.3 %,对阿米卡星、头孢替坦、左氧氟沙星、亚胺培南、环丙沙星的敏感率分别为59.4 %、68.8 %、81.3 %、75.0 %、81.3 %。非条件 Logistic回归分析显示血型A型、碳青霉烯类抗菌药物使用、引流、机械通气、糖尿病等为导致多重耐药菌肺炎克雷伯菌感染的独立危险因素(P<0.05)。结论：多重耐药菌肺炎克雷伯菌感染在呼吸道感染患者中比较常见,对头孢呋辛、氨苄西林的耐药率比较高,对左氧氟沙星、环丙沙星的敏感率比较高,血型A型、碳青霉烯类抗菌药物使用、引流、机械通气、糖尿病等为导致多重耐药菌肺炎克雷伯菌感染的独立危险因素。     

维生素A、E水平与儿童反复呼吸道感染的相关性和危险因素研究

摘要 目的：研究维生素A（VA）、维生素E（VE）水平与儿童反复呼吸道感染（RRI）的相关性和危险因素。方法：选择本院2017年1月~2019年10月诊治的318例RRI患儿,同期选择285例健康体检儿童作为对照组,比较各组VA、VE表达情况,并分析儿童RRI发生的危险因素。结果：RRI组VA及VE水平低于对照组,VA及VE缺乏率高于对照组,差异有统计学意义（P<0.05）。1~3岁患儿VA及VE水平高于3~6岁组且高于>6岁组（P<0.05）。对照组和RRI组性别、出生时体重比较无统计学差异（P>0.05）;RRI组自然分娩、母乳喂养率低于对照组,偏食、过敏体质、抗生素滥用、人均居住面积<13 m²、母亲文化高中及以下率高于对照组（P<0.05）。多因素Logistic回归分析显示,早产、偏食、过敏体质、被动吸烟、抗生素滥用、人均居住面积<13 m²是RRI发生的独立危险因素,VA、VE、自然分娩、母乳喂养、母亲文化程度是RRI发生的保护因素。结论：RRI儿童VA、VE水平较低,且RRI的发生和多种危险因素相关,临床应针对性的进行预防干预。     

Optimization of nutritional and environmental conditions for pyocyanin production by urine isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) is a highly pathogenic bacteria involved in numerous diseases among which, are urinary tract infections (UTIs). The pyocyanin secreted as a virulence factor by this bacterium has many beneficial applications but its high cost remains an obstacle for its widespread use. In this study, a total of fifty urine isolates were identified as P. aeruginosa. All strains produced pyocyanin pigment with a range of 1.3–31 µg/ml. The highest producer clinical strain P21 and the standard strain PA14 were used in optimization of pyocyanin production. Among tested media, king’s A fluid medium resulted in the highest yield of pyocyanin pigment followed by nutrient broth. Growth at 37 °C was superior in pyocyanin production than growth at 30 °C. Both shaking and longer incubation periods (3–4 days) improved pyocyanin production. The pyocyanin yield was indifferent upon growth of P21 at both pH 7 and pH 8. In conclusion, the optimum conditions for pyocyanin production are to use King’s A fluid medium of pH 7 and incubate the inoculated medium at 37 °C with shaking at 200 rpm for a period of three to four days.     

Gastrointestinal stress as innate defence against microbial attack

The human gastrointestinal (GI) tract has been bestowed with the most difficult task of protecting the underlying biological compartments from the resident commensal flora and the potential pathogens in transit through the GI tract. It has a unique environment in which several defence tactics are at play while maintaining homeostasis and health. The GI tract shows myriad number of environmental extremes, which includes pH variations, anaerobic conditions, nutrient limitations, elevated osmolarity etc., which puts a check to colonization and growth of nonfriendly microbial strains. The GI tract acts as a highly selective barrier/platform for ingested food and is the primary playground for balance between the resident and uninvited organisms. This review focuses on antimicrobial defense mechanisms of different sections of human GI tract. In addition, the protective mechanisms used by microbes to combat the human GI defence systems are also discussed. The ability to survive this innate defence mechanism determines the capability of probiotic or pathogen strains to confer health benefits or induce clinical events respectively.     

早产儿肠道微生态变化及其与胎龄、出生体质量的关系

目的探讨早产儿肠道微生态变化及其与胎龄、出生体质量的关系。方法选取2018年5月至2020年5月我院收治的80例早产儿作为早产组,同期收治的80例足月新生儿作为对照组。收集入组新生儿出生后3 d、3周的粪便,比较2组研究对象粪便标本中细菌丰富度和Shannon Wiener指数;根据早产组胎龄和出生体质量不同分组,分析胎龄、出生体质量与肠道微生态变化的关系。结果(1)出生3 d,早产组新生儿粪便标本的DGGE图谱条带数、Shannon Wiener指数均显著低于对照组(t=3.179、3.521,均P<0.05);(2)出生3 d,胎龄34⁺¹~36⁺⁶周组新生儿粪便标本的DGGE图谱条带数、Shannon Wiener指数显著高于28~30周组、30⁺¹~32周组和32⁺¹~34周组(q=9.653、6.476、4.848和8.796、8.008、6.277,均P<0.05);(3)出生3 d,体质量>2 000 g组新生儿粪便标本的的DGGE图谱条带数、Shannon Wiener指数显著高于≤1 500 g组(q=5.601和4.593,均P<0.05);(4)不同出生体质量、胎龄的早产儿,出生3周粪便标本的DGGE图谱条带数、Shannon Wiener指数相比差异无统计学意义(F=1.577和2.326,均P>0.05)。结论与足月新生儿相比,早产儿出生后细菌定植出现延迟且多样性差,胎龄越小、出生体质量越低的早产儿的肠道菌群的多样性更低、定植延迟的可能性更大,出生3周后其肠道微生态逐渐恢复正常。     

Honest signals and sexual conflict: Female lizards carry undesirable indicators of quality

Sex differences in animal coloration often result from sex‐dependent regulatory mechanisms. Still, some species exhibit incomplete sexual dimorphism as females carry a rudimentary version of a costly male trait, leading to intralocus sexual conflict. The underlying physiology and condition dependence of these traits can inform why such conflicts remain unresolved. In eastern fence lizards (Sceloporus undulatus), blue iridophore badges are found in males and females, but melanin pigmentation underneath and surrounding badges is male‐exclusive. We track color saturation and area of badges across sexual maturity, and their relationship to individual quality (body condition and immunocompetence) and relevant hormones (testosterone and corticosterone). Saturation and testosterone were positively correlated in both sexes, but hormone and trait had little overlap between males and females. Saturation was correlated with body condition and immunocompetence in males but not in females. Co‐regulation by androgens may have released females from resource allocation costs of color saturation, even when in high condition. Badge area was independent of testosterone, but associated with low corticosterone in females, indicating that a nonsex hormone underlies incomplete sexual dimorphism. Given the evidence in this species for female reproductive costs associated with ornamentation, this sex‐nonspecific regulation of an honest signal may underlie intralocus sexual conflict.     

Male competition reverses female preference for male chemical cues

Females must choose among potential mates with different phenotypes in a variety of social contexts. Many male traits are inherent and unchanging, but others are labile to social context. Competition, for example, can cause physiological changes that reflect recent wins and losses that fluctuate throughout time. We may expect females to respond differently to males depending on the outcome of their most recent fight. In Bolitotherus cornutus (forked fungus beetles), males compete for access to females, but copulation requires female cooperation. In this study, we use behavioral trials to determine whether females use chemical cues to differentiate between males and whether the outcome of recent male competition alters female preference. We measured female association time with chemical cues of two size‐matched males both before and after male–male competition. Females in our study preferred to associate with future losers before males interacted, but changed their preference for realized winners following male competitive interactions. Our study provides the first evidence of change in female preference based solely on the outcome of male–male competition.     

Female differential allocation in response to extrapair offspring and social mate attractiveness

Renewed debate over what benefits females might gain from producing extra‐pair offspring emphasizes the possibility that apparent differences in quality between within‐pair and extra‐pair offspring are confounded by greater maternal investment in extra‐pair offspring. Moreover, the attractiveness of a female''s social mate can also influence contributions of both partners to a reproductive attempt. Here, we explore the complexities involved in parental investment decisions in response to extra‐pair offspring and mate attractiveness with a focus on the female point of view. Adult zebra finches paired and reproduced in a colony setting. A male''s early‐life diet quality and his extra‐pair reproductive success were used as metrics of his mating attractiveness. Females paired with males that achieved extra‐pair success laid heavier eggs than other females and spent less time attending their nests than their mates or other females. Extra‐pair nestlings were fed more protein‐rich hen''s egg than within‐pair nestlings. Females producing extra‐pair offspring had more surviving sons than females producing only within‐pair offspring. Collectively, results show that females differentially allocate resources in response to offspring extra‐pair status and their social mate''s attractiveness. Females may also obtain fitness benefits through the production of extra‐pair offspring.