Using heterozygosity–fitness correlations to study inbreeding depression in an isolated population of white‐tailed deer founded by few individuals

A heterozygosity–fitness correlations (HFCs) may reflect inbreeding depression, but the extent to which they do so is debated. HFCs are particularly likely to occur after demographic disturbances such as population bottleneck or admixture. We here study HFC in an introduced and isolated ungulate population of white‐tailed deer Odocoileus virginianus in Finland founded in 1934 by four individuals. A total of 422 ≥ 1‐year‐old white‐tailed deer were collected in the 2012 hunting season in southern Finland and genotyped for 14 microsatellite loci. We find significant identity disequilibrium as estimated by g₂. Heterozygosity was positively associated with size‐ and age‐corrected body mass, but not with jaw size or (in males) antler score. Because of the relatively high identity disequilibrium, heterozygosity of the marker panel explained 51% of variation in inbreeding. Inbreeding explained approximately 4% of the variation in body mass and is thus a minor, although significant source of variation in body mass in this population. The study of HFC is attractive for game‐ and conservation‐oriented wildlife management because it presents an affordable and readily used approach for genetic monitoring that allowing identification of fitness costs associated with genetic substructuring in what may seem like a homogeneous population.     

Population genetics of orchid bees in a fragmented tropical landscape

The prospects for persistence of bees living in fragmented landscapes is a topic of considerable interest due to bees’ importance as pollinators of agricultural crops and wild plants, coupled with the ubiquity of native habitat loss and evidence that bees may be declining worldwide. Population persistence in fragmented areas depends on dispersal potential and maintenance of gene flow among fragments of habitat. Here we used population genetic techniques to characterize, for two equally abundant orchid bee species that differ in their physiology and ecology, levels of genetic differentiation among fragments of tropical forest in southeastern Costa Rica in a ~200 km² landscape. We measured population differentiation with ϕ_PT (an analogue to the traditional summary statistic Fst), as well as two measures that may more accurately reflect the level of differentiation when highly variable loci are used: G’st and D_est. We also calculated pairwise genetic distances among individuals and conducted Mantel tests to test the correlation of genetic and geographic distance, for each species. We found strong differences in genetic structure between the species. Contrary to our expectations, each measure of genetic structure revealed that the larger-bodied species, Eulaema bombiformis, had higher levels of differentiation than the smaller species, Euglossa championi. Furthermore, for Eulaema bombiformis there was a significant positive correlation of genetic and geographic distance while for Euglossa championi there was no significant positive correlation. Our results demonstrate that bee species can have strikingly different levels of gene flow in fragmented habitats, and that body size may not always act as a useful proxy for dispersal, even in closely related taxa.     

Genetic demography of Antioquia (Colombia) and the Central Valley of Costa Rica

We report a comparative genetic characterization of two population isolates with parallel demographic histories: the Central Valley of Costa Rica (CVCR) and Antioquia (in northwest Colombia). The analysis of mtDNA, Y-chromosome and autosomal polymorphisms shows that Antioquia and the CVCR are genetically very similar, indicating that closely related parental populations founded these two isolates. In both populations, the male ancestry is predominantly European, whereas the female ancestry is mostly Amerind. In agreement with their isolation, the Amerindian mtDNA diversity of Antioquia and the CVCR is typical of ethnically-defined native populations and is markedly lower than in other Latin American populations. A comparison of linkage disequilibrium (LD) at 18 marker pairs in Antioquia and the CVCR shows that markers in LD in both populations are located at short genetic distances (相似文献   

Complement factor H allotype 402H is associated with increased C3b opsonization and phagocytosis of Streptococcus pyogenes

The main virulence factor of group A streptococcus (GAS), M protein, binds plasma complement regulators factor H (FH) and FH-like protein 1 (FHL-1) leading to decreased opsonization. The M protein binding site on FH is within domain 7 in which also the age-related macular degeneration (AMD)-associated polymorphism Y402H is located. We studied if FH allotypes 402H and 402Y have different binding affinities to GAS. Plasma-derived FH allotype 402H and its recombinant fragment FH5-7(402H) showed decreased binding to several GAS strains. Growth of GAS in human blood taken from FH(402H) homozygous individuals was decreased when compared with blood taken from FH(402Y) homozygous individuals. The effect of the allotype 402H can be explained by combining the previous M protein mutagenesis data and the recently published crystal structure of FH6-8. In conclusion the data indicate that the AMD-associated allotype 402H leads to diminished binding of FH to GAS and increased opsonophagocytosis of the bacteria in blood. These results suggest that the homozygous presence of the allele 402H could be associated with decreased risk for severe GAS infections offering an explanation for the high frequency of the allele despite its association with visual impairment.     

Potential role of subunit c of F0F1-ATPase and subunit c of storage body in the mitochondrial permeability transition. Effect of the phosphorylation status of subunit c on pore opening

Phosphorylated and non-phosphorylated forms of the F₀F₁-ATPase subunit c from rat liver mitochondria (RLM) were purified and their effect on the opening of the permeability transition pore (mPTP) was investigated. Addition of dephosphorylated subunit c to RLM induced mitochondrial swelling, decreased the membrane potential and reduced the Ca²⁺ uptake capacity, which was prevented by cyclosporin A. The same effect was observed in the presence of storage subunit c purified from livers of sheep affected with ceroid lipofuscinosis. In black-lipid bilayer membranes subunit c increased the conductance due to formation of single channels with fast and slow kinetics. The dephosphorylated subunit c formed channels with slow kinetics, i.e. the open state being of significantly longer duration than in the case of channels formed by the phosphorylated form that had short life spans and fast kinetics. The channels formed were cation-selective more so with the phosphorylated form. Subunit c of rat liver mitochondria was able to bind Ca²⁺. Collectively, the data allowed us to suppose that subunit c F₀F₁-ATPase might be a structural/regulatory component of mPTP exerting its role in dependence on phosphorylation status.     

Growth performance and feed conversion of Ruspolia differens on plant-based by-product diets

The use of food industry by-products in insect feeds has gained increasing attention recently. However, the understanding of how well the economically valuable edible insect Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) can grow and develop with plant-based by-product feeds is currently lacking. It is important to determine the nutritional requirements, especially protein demand, of this species before developing artificial feeds for mass-rearing. We reared R. differens with four control diets and 12 plant-based by-product diets in which the major protein source came from food industry by-products, including potato-protein, barley mash, barley feed, turnip rape, a mix of broad bean and pea, and a mix of potato, carrot, and apple. We asked whether the performance (development time, survival, and weight), feed conversion, and fatty acid composition and content differed among diet treatments. Furthermore, the 12 experimental by-product diets were designed to reach six protein levels. We found that R. differens can be reared with various by-product diets, but development time, survival, and weight differed among diets. Barley feed, barley mash, and potato protein diets seem to be good options for rearing, and potato glycoalkaloids do not affect the performance of R. differens. Individuals fed on the various by-product diets also differed in their fatty acid composition and content. Increasing protein levels in diet up to 17% enhanced growth, development time, and survival, but no further enhancements were seen when fed diets with protein levels higher than this. The high protein levels decreased feed conversion rate. Our results can be valuable for designing feeds for insect mass-rearing technology. The use of food industry by-products in the diets for R. differens could increase the re-use of local resources and enhance circular economy.     

Growth of legionella and other heterotrophic bacteria in a circulating cooling water system exposed to ultraviolet irradiation

The effect of ultraviolet irradiation on the growth and occurrence of legionella and other heterotrophic bacteria in a circulating cooling water system was studied. Water of the reservoir was circulated once in 28 h through a side-stream open channel u.v. radiator consisting of two lamps. Viable counts of legionellas and heterotrophic bacteria in water immediately after the u.v. treatment were 0—12 and 0·7—1·2% of those in the reservoir, respectively. U.v. irradiation increased the concentration of easily assimilable organic carbon. In the u.v. irradiated water samples incubated in the laboratory the viable counts of heterotrophic bacteria reached the counts in reservoir water within 5 d. The increase in viable counts was mainly due to reactivation of bacterialcells damaged by u.v. light, not because of bacterial multiplication. Despite u.v. irradiation the bacterial numbers in the reservoir water, including legionellas, did not decrease during the experimental period of 33 d. The main growth of bacteria in the reservoir occurred in biofilm and sediment, which were never exposed to u.v. irradiation.     

Minor effects of long-term ozone exposure on boreal peatland species Eriophorum vaginatum and Sphagnum papillosum

The effects of long-term ozone fumigation on two common peatland plant species, a sedge Eriophorum vaginatum L. and a moss Sphagnum papillosum Lindb., were studied applying peatland microcosms. The peat cores with intact vegetation were cored from an oligotrophic pine fen and partially embedded into the soil of an open-air experimental field for four growing seasons. The open-air ozone exposure field consists of eight circular plots of which four were fumigated with elevated ozone concentration (doubled ambient) and four were ambient controls. The results showed that E. vaginatum and S. papillosum can tolerate ozone better than expected. Elevated ozone concentration did not affect overall relative length growth of E. vaginatum or S. papillosum. The leaf cross-section area of E. vaginatum leaves was 8% bigger in the ozone treatment compared to that in the ambient control. Ultrastuctural variables did not show any significant treatment effect in E. vaginatum or in S. papillosum. Total chlorophyll (a + b) concentration tended to increase in early growing season under ozone exposure. During the first growing season, elevated ozone concentration decreased methanol-extractable, UV-absorbing compounds in E. vaginatum. The results suggest that E. vaginatum and S. papillosum are ozone tolerant plant species and are likely able to cope with expected increase in tropospheric ozone concentration.     

Drought effects on volatile organic compound emissions from Scots pine stems

Tree stems have been identified as sources of volatile organic compounds (VOCs) that play important roles in tree defence and atmospheric chemistry. Yet, we lack understanding on the magnitude and environmental drivers of stem VOC emissions in various forest ecosystems. Due to the increasing importance of extreme drought, we studied drought effects on the VOC emissions from mature Scots pine (Pinus sylvestris L.) stems. We measured monoterpenes, acetone, acetaldehyde and methanol emissions with custom-made stem chambers, online PTR-MS and adsorbent sampling in a drought-prone forest over the hot-dry summer of 2018 and compared the emission rates and dynamics between trees in naturally dry conditions and under long-term irrigation (drought release). The pine stems were significant monoterpene sources. The stem monoterpene emissions potentially originated from resin, based on their similar monoterpene spectra. The emission dynamics of all VOCs followed temperature at a daily scale, but monoterpene and acetaldehyde emission rates decreased nonlinearly with drought over the summer. Despite the dry conditions, large peaks of monoterpene, acetaldehyde and acetone emissions occurred in late summer potentially due to abiotic or biotic stressors. Our results highlight the potential importance of stem emissions in the ecosystem VOC budget, encouraging further studies in diverse environments.