蜜蜂及熊蜂微孢子虫rRNA基因研究

核糖体RNA(rRNA)是一种理想的进化计时器,已广泛地应用于研究微生物的系统发育和进化关系。蜜蜂和熊蜂都被微孢子虫感染,关于蜜蜂和熊蜂微孢子虫rRNA基因研究主要有rRNA基因序列的测定分析、二级结构的研究和用rRNA基因检测诊断微孢子虫等。这些对蜜蜂和熊蜂微孢子虫系统发育的研究和微孢子虫的防治等具有重要的推动作用。     

Activity patterns of females of the solitary bee Anthophora plumipes in relation to temperature, nectar supplies and body size

Abstract.

• 1 Patterns of activity at a large nesting aggregation and at foraging sites are described for females of the solitary bee Anthophora plumipes (Pallas). Changes in the quality and quantity of the resource collected by females provisioning cells are related to variation in female body mass and microclimate.
• 2 Activity at the nest site demonstrated relationships with aspects of the thermal environment experienced by A.plumipes. Measures of temperature showing significant relationships differed for females in different stages in the nesting cycle exhibiting characteristically different behaviour patterns.
• 3 Larger females emerged from nest tunnels earlier in the morning and provisioned cells at lower ambient temperatures than smaller individuals. Body size therefore predicts reproductive success at low ambient temperatures.
• 4 Pollen and nectar loads carried by females increased with ambient temperature. Because only one cell is completed per day and the size of offspring is determined by the quality and quantity of resource provided by the mother, the body size of individuals emerging in the following season will depend on interactions between climate and body size, in addition to any heritable component.
• 5 Variation in activity levels at foraging sites is attributed not only to thermal considerations, but also to variation in the quality of rewards available at different floral sources.

     

Sex‐specific patterns of fuelling and pre‐breeding body moult of Little Stints Calidris minuta in South Africa

The timing and duration of each stage of the life of a long‐distance migrant bird are constrained by time and resources. If the parental roles of males and females differ, the timing of other life stages, such as moult or pre‐migratory fuelling, may also differ between the sexes. Little is known about sexual differences for species with weak sexual dimorphism, but DNA‐sexing enables fresh insights. The Little Stint Calidris minuta is a monomorphic long‐distance migrant wader breeding in the Arctic tundra. Males compete for territories and perform elaborate aerial displays. Females produce two clutches a season. Each sex may be a bigamist and incubate one nest a season, each with a different partner. We expect that these differences in breeding behaviour entail different preparations for breeding by males and females, so we aimed to determine whether Little Stints showed any sex differences in their strategies for pre‐breeding moult and pre‐migratory fuelling at their non‐breeding grounds in South Africa. We used body moult records, wing length and body mass of 241 DNA‐sexed Little Stints that we caught and ringed between 27 January and 29 April in 2008–2018 at two neighbouring wetlands in North West Province, South Africa. For each individual we assessed the percentage of breeding plumage on its upperparts and took blood samples for DNA‐sexing. We calculated an adjusted Body Moult Index and an adjusted Wing Coverts Moult Index, then used the Underhill–Zucchini moult model to estimate the start dates and the rate of body moult in males and females. We estimated the changes in the sex ratio of the local population during their stay in South Africa, and also estimated the timing and rate of pre‐migratory fuelling and the potential flight ranges for males and females. The males started body moult on average on 7 February and the females on 12 February, but the sexes did not differ in their timing of wing covert moult, which started on average on 10 February. In January to mid‐February, males constituted c. 57% of the population, but their proportion declined afterwards, indicating an earlier departure than females. We estimated that both sexes began pre‐migratory fuelling on average on 15 March. The sexes did not differ in fuelling rate, but most females stayed at the non‐breeding site longer than the males, and thus accumulated more fuel and had longer potential flight ranges. These patterns of moult and fuelling suggest sex differences in preparations for breeding. We suggest that the males depart from South Africa earlier but with smaller fuel loads than the females to establish breeding territories before the females arrive. We conclude that for each sex the observed trade‐offs between fuelling and moult at the non‐breeding grounds are precursors to different migration strategies, which in turn are adaptations for their different roles in reproductive behaviour.     

Elevation of vitellogenin expression in Sunn pest is associated with pre‐migration and migration phases of the life cycle

Sunn pest, Eurygaster maura L. (Hemiptera: Scutelleridae), a species with an obligatory diapause, is a major destructive pest of cereal products in central Asia, Europe and North Africa. Adults feed voraciously, causing total destruction of wheat fields in just a couple of days. Insect vitellogenins (Vgs) play a major role in reproduction by supplying the resources needed for oocyte development. In this study, we identified and characterized three E. maura Vg genes (EmVgs: EmVg1, EmVg2 and EmVg3) in the cDNA library generated from the fat body of overwintering E. maura. We examined expression levels of EmVgs in the phases of the life cycle, different tissues and at different developmental stages. mRNA levels in the female adults started to increase in the pre‐migration phase and reached peak level in the adults that freshly migrated to lowlands. This pattern suggests that the elevation of EmVg expression is associated with pre‐migration and migration phases of the insect's life cycle. EmVgs were primarily expressed in the fat body, which could be a possible EmVg expression site. EmVgs were expressed throughout developmental stages, suggesting that they might be prominent for nymphal development of E. maura.     

Clathrin‐dependent endocytosis predominantly mediates protein absorption by fat body from the hemolymph in Bombyx mori

During insect larval–pupal metamorphosis, proteins in the hemolymph are absorbed by the fat body for the maintenance of intracellular homeostasis; however, the type of proteins and how these proteins are internalized into the fat body are unclear. In Bombyx mori, the developmental profiles of total proteins in the hemolymph and fat body showed that hemolymph‐decreased protein bands (55–100 kDa) were in accordance with those protein bands that increased in the fat body. Inhibition of clathrin‐dependent endocytosis predominantly blocked the transportation of 55–100 kDa proteins from the hemolymph into the fat body, which was further verified by RNA interference treatment of Bmclathrin. Six hexamerins were shown to comprise ～90% of the total identified proteins in both the hemolymph and fat body by mass spectrum (MS) analysis. In addition, hemolymph‐specific proteins were mainly involved in material transportation, while fat body‐specific proteins particularly participated in metabolism. In this paper, four hexamerins were found for the first time, and potential proteins absorbed by the fat body from the hemolymph through clathrin‐dependent endocytosis were identified. This study sheds light on the protein absorption mechanism during insect metamorphosis.     

Differences in the pre‐diapause and pre‐oviposition accumulation of critical nutrients in adult females of the beetle Colaphellus bowringi

In many insect species, the differentiation of development between diapause and reproduction first becomes obvious during the diapause preparation (pre‐diapause) and pre‐oviposition phases. However, the differentiation of nutrient accumulation between these two phases remains unclear. We compared the weights of pre‐diapause and reproductive adult female Colaphellus bowringi Baly (Coleoptera: Chrysomelidae), and measured their triacylglycerol (TAG), protein, and carbohydrate content from emergence until they had fed for 4 days post‐eclosion. We also compared the ovarian development and accumulation of lipid droplets between pre‐diapause and reproductive adult females in order to determine whether we could visually detect differences in nutrient allocation. The weights of both pre‐diapause and reproductive females increased with duration of feeding. The fresh weight and water content of pre‐diapause females was significantly lower than that of reproductive females after feeding for 3 days post‐eclosion. Pre‐diapause females channeled their reserves into TAG in the fat body, whereas reproductive females converted nutrients into proteins and carbohydrates for egg development. These results quantify differences in nutrient accumulation between pre‐diapause and reproductive adult female C. bowringi, and provide clues for understanding the molecular mechanisms underlying differences in the allocation of nutrients between diapause and reproduction in insects.     

Transcriptome analysis reveals the difference between “healthy” and “common” aging and their connection with age‐related diseases

A key goal of aging research was to understand mechanisms underlying healthy aging and develop methods to promote the human healthspan. One approach is to identify gene regulations unique to healthy aging compared with aging in the general population (i.e., “common” aging). Here, we leveraged Genotype‐Tissue Expression (GTEx) project data to investigate “healthy” and “common” aging gene expression regulations at a tissue level in humans and their interconnection with diseases. Using GTEx donors' disease annotations, we defined a “healthy” aging cohort for each tissue. We then compared the age‐associated genes derived from this cohort with age‐associated genes from the “common” aging cohort which included all GTEx donors; we also compared the “healthy” and “common” aging gene expressions with various disease‐associated gene expressions to elucidate the relationships among “healthy,” “common” aging and disease. Our analyses showed that 1. GTEx “healthy” and “common” aging shared a large number of gene regulations; 2. Despite the substantial commonality, “healthy” and “common” aging genes also showed distinct function enrichment, and “common” aging genes had a higher enrichment for disease genes; 3. Disease‐associated gene regulations were overall different from aging gene regulations. However, for genes regulated by both, their regulation directions were largely consistent, implying some aging processes could increase the susceptibility to disease development; and 4. Possible protective mechanisms were associated with some “healthy” aging gene regulations. In summary, our work highlights several unique features of GTEx “healthy” aging program. This new knowledge could potentially be used to develop interventions to promote the human healthspan.     

Nutritional factors and gender influence age‐related DNA methylation in the human rectal mucosa

Aberrant methylation of CpG islands (CGI) occurs in many genes expressed in colonic epithelial cells, and may contribute to the dysregulation of signalling pathways associated with carcinogenesis. This cross‐sectional study assessed the relative importance of age, nutritional exposures and other environmental factors in the development of CGI methylation. Rectal biopsies were obtained from 185 individuals (84 male, 101 female) shown to be free of colorectal disease, and for whom measurements of age, body size, nutritional status and blood cell counts were available. We used quantitative DNA methylation analysis combined with multivariate modelling to investigate the relationships between nutritional, anthropometric and metabolic factors and the CGI methylation of 11 genes, together with LINE‐1 as an index of global DNA methylation. Age was a consistent predictor of CGI methylation for 9/11 genes but significant positive associations with folate status and negative associations with vitamin D and selenium status were also identified for several genes. There was evidence for positive associations with blood monocyte levels and anthropometric factors for some genes. In general, CGI methylation was higher in males than in females and differential effects of age and other factors on methylation in males and females were identified. In conclusion, levels of age‐related CGI methylation in the healthy human rectal mucosa are influenced by gender, the availability of folate, vitamin D and selenium, and perhaps by factors related to systemic inflammation.