Effects of nutrient limitation on sperm and seminal fluid: a systematic review and meta‐analysis

Theory predicts that costly sexual traits should be reduced when individuals are in poor condition (i.e. traits should exhibit condition‐dependent expression). It is therefore widely expected that male ejaculate traits, such as sperm and seminal fluid, will exhibit reduced quantity and quality when dietary nutrients are limited. However, reported patterns of ejaculate condition dependence are highly variable, and there has been no comprehensive synthesis of underlying sources of such variation in condition‐dependent responses. In particular, it remains unclear whether all ejaculate traits are equally sensitive to nutrient intake, and whether such traits are particularly sensitive to certain dietary nutrients, respond more strongly to nutrients during specific life stages, or respond more strongly in some taxonomic groups. We systematically reviewed these potential sources of variation through a meta‐analysis across 50 species of arthropods and vertebrates (from 71 papers and 348 effect sizes). We found that overall, ejaculate traits are moderately reduced when dietary nutrients are limited, but we also detected substantial variation in responses. Seminal fluid quantity was strongly and consistently condition dependent, while sperm quantity was moderately condition dependent. By contrast, aspects of sperm quality (particularly sperm viability and morphology) were less consistently reduced under nutrient limitation. Ejaculate traits tended to respond in a condition‐dependent manner to a wide range of dietary manipulations, especially to caloric and protein restriction. Finally, while all major taxa for which sufficient data exist (i.e. arthropods, mammals, fish) showed condition dependence of ejaculate traits, we detected some taxonomic differences in the life stage that is most sensitive to nutrient limitation, and in the degree of condition dependence of specific ejaculate traits. Together, these biologically relevant factors accounted for nearly 20% of the total variance in ejaculate responses to nutrient limitation. Interestingly, body size showed considerably stronger condition‐dependent responses compared to ejaculate traits, suggesting that ejaculate trait expression may be strongly canalised to protect important reproductive functions, or that the cost of producing an ejaculate is relatively low. Taken together, our findings show that condition‐dependence of ejaculate traits is taxonomically widespread, but there are also many interesting, biologically relevant sources of variation that require further investigation. In particular, further research is needed to understand the differences in selective pressures that result in differential patterns of ejaculate condition dependence across taxa and ejaculate traits.     

Soil depth- and root diameter-related variations affect root decomposition in temperate pine and oak forests

Aims Assessment of factors regulating root decomposition is needed to understand carbon and nutrient cycling in forest ecosystems. The objective of this study is to examine the effects of soil depth and root diameter on root decomposition and to analyze the relationship of root decomposition with factors such as soil environmental conditions and initial litter quality.     

Assessing,with limited resources,the ecological outcomes of wetland restoration: a South African case

Resources for evaluating the ecological outcomes of ecosystem restoration projects are often limited, especially within government‐funded programs. In order to rapidly assess the ecological outcomes of wetland restoration, an improved approach has been developed, which was applied in the assessment of the ecological outcomes at nine restoration sites of South Africa's Working for Wetlands program. The sites encompass a diversity of restoration problems and land use contexts. The approach begins by distinguishing hydrogeomorphic (HGM) units, for which ecological condition is assessed and reported for hydrology, geomorphology, and vegetation pre‐ and post‐restoration. These three components are closely linked but, as demonstrated at some of the sites, may respond differentially to restoration interventions. For most HGM units, overall ecological condition was improved by between 10 and 30%, with the greatest contribution of restoration generally being to the hydrology component. Having determined the integrity and costs of the interventions, cost‐effectiveness is then reported in South African Rands per hectare equivalent restored, which was found to vary by more than an order of magnitude across the HGM units assessed. Cost‐effectiveness must be interpreted in the light of the long‐term integrity of the interventions, the site's landscape context, and the contribution of restoration to ecosystem services provision. Some sites may be considerably less cost‐effective than others, but the cost may nonetheless be justified if the sites make key contributions to ecosystem services provision. The study was conducted in the context of a formative evaluation and the findings are envisaged to improve wetland restoration practice.     

Is the removal of aboveground shrub biomass an effective technique to restore a shrub‐encroached grassland?

Encroachment of woody plants into grasslands is a global phenomenon that has substantial impacts on pastoral productivity and ecosystem services. Over the past half century, pastoralists and land management agencies have explored various options to control woody plants in order to improve ecosystem services in shrub‐encroached grasslands. We examined the effectiveness of controlling the encroachment of the shrub Caragana microphylla into grassland in Inner Mongolia, China. We cut and removed all of the aboveground biomass from 450 shrubs, predicting that the effectiveness of this technique to control shrubs would depend on shrub morphology. Specifically, we expected that larger shrubs with more biomass would be more difficult to kill by cutting than smaller shrubs. A year after treatment, we found that cutting killed only 11% of the 450 treated shrubs, and of these, three‐quarters of the locations that they occupied reverted to grasses and one‐quarter to bare soil. Shrubs that survived the cutting treatment produced more stems and leaf biomass, and therefore had a greater leaf to stem ratio. Shrubs that died after cutting had a lower crown area and basal area, and less stem biomass than shrubs that resprouted within 12 months of cutting. There were no effects of shrub height on the fate of treated shrubs. Cutting had no effect on understory plant cover or richness, but reproductive plants were taller under shrubs that were not cut. Overall, our study showed that removing aboveground shrub biomass by cutting is an ineffective technique for “restoring” the original grassland community unless shrubs are very small. Strategic targeting of small shrubs would be a more effective technique for controlling the spread of C. microphylla in the long term.     

益生菌联合早期肠内营养干预对 重症脑卒中患者营养状态及肠道菌群的影响

目的探讨益生菌联合早期肠内营养干预对重症脑卒中患者营养状态及肠道菌群的影响。方法选取2014年1月至2018年6月于我院住院治疗的重症脑卒中患者70例,随机分为观察组和对照组各35例。两组患者均予控制颅内压、营养神经细胞、抗生素预防感染、保护胃黏膜和维持水电解质酸碱平衡等基础治疗。对照组患者留置鼻饲管行常规肠内营养治疗,观察组患者在对照组治疗基础上加用双歧杆菌四联活菌片水化后鼻饲管注入,1.5 g/次,3次/d,连用10 d。观察两组患者治疗前和治疗10 d后营养状态指标[血清总蛋白(TP)、转铁蛋白(TF)、上臂三头肌肌围(MAMC)]的变化,并比较治疗后肠道菌群(双歧杆菌、乳杆菌、拟杆菌、肠球菌、大肠埃希菌)数量变化。结果治疗10 d后,两组患者血清TP、TF水平和MAMC较治疗前显著下降(P0.05),且治疗后观察组患者TP、TF水平和MAMC高于对照组(P0.05);同时治疗后观察组患者粪便中双歧杆菌、乳杆菌和拟杆菌数量高于对照组,肠球菌和大肠埃希菌数量低于对照组(P0.05)。结论益生菌联合早期肠内营养干预不仅可显著减缓重症脑卒中患者的营养状态恶化;而且能有效地纠正肠道菌群失调,维持肠道微生态的稳定。     

大肠杆菌角鲨烯合成途径的构建与调控

角鲨烯因其具有良好的抗氧化功能而被广泛应用于食品、医药、化妆品、工业应用等领域。本实验在大肠杆菌中构建角鲨烯合成途径,通过对其合成途径中关键限速酶(1-脱氧-D-木酮糖-5-磷酸合酶和异戊烯基二磷酸异构酶)过表达的方法进行初步调控,使角鲨烯的产量提升了近三倍。之后采用单因素试验对其发酵培养基和培养条件进行优化,以此来提高角鲨烯的产量。优化发酵条件后,使用最优发酵培养基——TB培养基,在最佳发酵条件:37℃,220r/min培养至OD600约为1.2时加入终浓度为0.1mmol/L的IPTG诱导剂,25℃条件下诱导48h,角鲨烯产量可达73.88mg/L。     

Does inbreeding affect personality traits?

The question of why variation is maintained in personality traits is an evolutionary puzzle. According to the condition‐dependence hypothesis, such traits depend on condition, which limits the behavioral choices available to individuals. Because condition is affected by many genes, it can effectively be manipulated by inbreeding, which exposes the effects of deleterious recessive mutations. Here, I compared two personality traits, boldness and tendency to explore, of male guppies (Poecilia reticulata) from first‐generation inbred and outbred treatments. Boldness in guppies is associated with increased sexual attractiveness and is thus expected to affect fitness. Therefore, I hypothesized that the personality traits would be negatively affected by inbreeding. However, the results indicated that inbred guppies did not differ in either personality trait from their outbred counterparts. This finding suggests that mechanisms other than condition dependence are maintaining personality variation in the guppy.     

Dynamic responses of picophytoplankton to physicochemical variation in the eastern Indian Ocean

Picophytoplankton were investigated during spring 2015 and 2016 extending from near‐shore coastal waters to oligotrophic open waters in the eastern Indian Ocean (EIO). They were typically composed of Prochlorococcus (Pro), Synechococcus (Syn), and picoeukaryotes (PEuks). Pro dominated most regions of the entire EIO and were approximately 1–2 orders of magnitude more abundant than Syn and PEuks. Under the influence of physicochemical conditions induced by annual variations of circulations and water masses, no coherent abundance and horizontal distributions of picophytoplankton were observed between spring 2015 and 2016. Although previous studies reported the limited effects of nutrients and heavy metals around coastal waters or upwelling zones could constrain Pro growth, Pro abundance showed strong positive correlation with nutrients, indicating the increase in nutrient availability particularly in the oligotrophic EIO could appreciably elevate their abundance. The exceptional appearance of picophytoplankton with high abundance along the equator appeared to be associated with the advection processes supported by the Wyrtki jets. For vertical patterns of picophytoplankton, a simple conceptual model was built based upon physicochemical parameters. However, Pro and PEuks simultaneously formed a subsurface maximum, while Syn generally restricted to the upper waters, significantly correlating with the combined effects of temperature, light, and nutrient availability. The average chlorophyll a concentrations (Chl a) of picophytoplankton accounted for above 49.6% and 44.9% of the total Chl a during both years, respectively, suggesting that picophytoplankton contributed a significant proportion of the phytoplankton community in the whole EIO.     

樟叶越桔细胞悬浮培养条件的优化

为了提高樟叶越桔(Vaccinium dunalianum)悬浮培养细胞的生物量, 以樟叶越桔叶片愈伤组织为试材, 通过单因素试验探究不同蔗糖浓度、培养基pH值、培养基体积、初始接种量和摇床转速对悬浮培养细胞生长的影响, 并根据响应面法Box-Behnken试验设计原理进行组合试验以优化培养条件。结果显示, 以改良WPM培养基为基础培养基, 樟叶越桔细胞悬浮培养的最优条件为40 g·L^-1蔗糖、培养基pH5.2、培养基体积45 mL、初始接种量2.64 g和摇床转速为149 r·min^-1, 其细胞生物量干重为0.184 4 g, 与理论预测值0.184 5 g较为接近, 且细胞的生长曲线呈S型。研究结果为樟叶越桔悬浮培养细胞次生代谢产物的生产调控奠定了技术基础。