Low heat shock thresholds in wild Antarctic inter-tidal limpets (Nacella concinna)

Heat shock proteins (HSPs) are a family of genes classically used to measure levels of organism stress. We have previously identified two HSP70 genes (HSP70A and HSP70B) in sub-tidal populations of the Antarctic limpet (Nacella concinna). These genes are up-regulated in response to increased seawater temperatures of 15°C or more during acute heat shock experiments, temperatures that have very little basis when considering the current Antarctic ecology of these animals. Therefore, the question was posed as to whether these animals could express HSP70 genes when subjected to more complex environmental conditions, such as those that occur in the inter-tidal. Inter-tidal limpets were collected on three occasions in different weather conditions at South Cove, Rothera Point, over a complete tidal cycle, and the expression levels of the HSP70 genes were measured. Both genes showed relative up-regulation of gene expression over the period of the tidal cycle. The average foot temperature of these animals was 3.3°C, far below that of the acute heat shock experiments. These experiments demonstrate that the temperature and expression levels of HSP production in wild animals cannot be accurately extrapolated from experimentally induced treatments, especially when considering the complexity of stressors in the natural environment. However, experimental manipulation can provide molecular markers for identifying stress in Antarctic molluscs, provided it is accompanied by environmental validation, as demonstrated here. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Alien dominance of the parasitoid wasp community along an elevation gradient on Hawai’i Island

Through intentional and accidental introduction, more than 100 species of alien Ichneumonidae and Braconidae (Hymenoptera) have become established in the Hawaiian Islands. The extent to which these parasitoid wasps have penetrated native wet forests was investigated over a 1,765 m elevation gradient on windward Hawai’i Island. For >1 year, malaise traps were used to continuously monitor parasitoid abundance and species richness in nine sites over three elevations. A total of 18,996 individuals from 16 subfamilies were collected. Overall, the fauna was dominated by aliens, with 44 of 58 species foreign to the Hawaiian Islands. Ichneumonidae was dominant over Braconidae in terms of both diversity and abundance, comprising 67.5% of individuals and 69.0% of species collected. Parasitoid abundance and species richness varied significantly with elevation: abundance was greater at mid and high elevations compared to low elevation while species richness increased with increasing elevation, with all three elevations differing significantly from each other. Nine species purposely introduced to control pest insects were found, but one braconid, Meteorus laphygmae, comprised 98.0% of this assemblage, or 28.3% of the entire fauna. Endemic species, primarily within the genera Spolas and Enicospilus, were collected almost exclusively at mid- and high-elevation sites, where they made up 22.1% and 36.0% of the total catch, respectively. Overall, 75.9% of species and 96.0% of individuals are inferred to parasitize Lepidoptera larvae and pupae. Our results support previous data indicating that alien parasitoids have deeply penetrated native forest habitats and may have substantial impacts on Hawaiian ecosystems.     

World distribution of female flight and genetic variation in Lymantria dispar (Lepidoptera: Lymantriidae)

Female gypsy moths, Lymantria dispar L., from 46 geographic strains were evaluated for flight capability and related traits. Males from 31 of the same strains were evaluated for genetic diversity using two polymorphic cytochrome oxidase I mitochondrial DNA restriction sites, the nuclear FS1 marker, and four microsatellite loci. Females capable of strong directed flight were found in strains that originated from Asia, Siberia, and the northeastern parts of Europe, but flight capability was not fixed in most strains. No flight-capable females were found in strains from the United States or southern and western Europe. Wing size and musculature were shown to correlate with flight capability and potentially could be used in predicting female flight capability. The mtDNA haplotypes broadly separated the gypsy moth strains into three groups: North American, European/Siberian, and Asian. Specific microsatellite or FS1 alleles were only fixed in a few strains, and there was a gradual increase in the frequency of alleles dominant in Asia at both the nuclear and microsatellite loci moving geographically from west to east. When all the genetic marker information was used, 94% of the individuals were accurately assigned to their broad geographic group of origin (North American, European, Siberian, and Asian), but female flight capability could not be predicted accurately. This suggests that gene flow or barriers to it are important in determining the current distribution of flight-capable females and shows the need for added markers when trying to predict female flight capability in introduced populations, especially when a European origin is suspected.     

Empowering marine science through genomics

Marine scientists in Europe summarize their successes with genome technologies in the marine sciences and make a plea for a concerted international effort to raise greater public education for support.     

Responses of invertebrates and algae of a boreal coniferous forest stream to experimental manipulation of leaf litter inputs and shading

Forest harvesting alters leaf litter inputs and shading of small streams. Most of the previous studies of harvesting effects are limited to coastal or deciduous forests, so here we consider a sub-boreal forest stream. To test the hypothesis that changes in light and litter inputs would affect the benthic community in these streams, we experimentally manipulated these variables in stream mesocosms. We used a 2 × 2 factorial design with light (shaded or full light) and leaf litter inputs (equivalent to a forested stream or one quarter that rate) as factors. The high leaf litter treatment resulted in differences in macroinvertebrate community composition and higher densities of two shredders, Limnephilus sp. and Podmosta sp., suggesting food limitation. Algal filaments were longer in the high light treatments indicating a change in periphyton composition. There were no significant differences in chlorophyll a or ash-free dry mass, suggesting that light was not limiting to periphyton. The community structure clearly shifted in response to both resources, although primarily to detrital inputs. These results provide evidence that changes to shading and leaf inputs to small streams can affect the benthos and may limit secondary production.     

Pharmacokinetics and stability of the ch14.18–interleukin-2 fusion protein in mice

The fusion protein formed from ch14.18 and interleukin-2 (ch14.18-IL-2), shown to exhibit antitumor efficacy in mouse models, consists of IL-2 genetically linked to each heavy chain of the ch14.18 chimeric anti-GD2 monoclonal antibody. The purpose of this study was to determine the pharmacokinetics of ch14.18-IL-2 in mice and assess its stability in murine serum. Following i.v. injection, the fusion protein was found to have a terminal half-life of 4.1 h. Detection of IL-2 following injection of the ch14.18-IL-2 fusion protein showed a similar half-life, indicating that the fusion protein prolongs the circulatory half-life of IL-2. Detection of human IgG1 following injection of ch14.18-IL-2 showed a terminal half-life of 26.9 h. These data suggested that the native fusion protein is being altered in vivo, resulting in a somewhat rapid loss of detectable IL-2, despite prolonged circulation of its immunoglobulin components. In vitro incubation of the ch14.18-IL-2 fusion protein in pooled mouse serum at 37 degrees C for 48 h resulted in a loss of its IL-2 component, as detected in enzyme-linked immunosorbent assay systems and in proliferation assays. Polyacrylamide gel electrophoresis and Western blot analysis of the fusion protein incubated in mouse serum at 37 degrees C indicated that the ch14.18-IL-2 is cleaved, resulting in a loss of the 67-kDa band (representing the IL-2 linked to the IgG1 heavy chain) and the detection of a band of more than 50 kDa, slightly heavier than the IgG1 heavy chain itself. This suggests that the fusion protein is being cleaved in vitro within the IL-2 portion of the molecule. These studies show that (1) ch14.18-IL-2 prolongs the circulatory half-life of IL-2 (compared to that of soluble IL-2) and (2) the in vivo clearance of the fusion protein occurs more rapidly than the clearance of the ch14.18 antibody itself, possibly reflecting in vivo cleavage within the IL-2 portion of the molecule, resulting in loss of IL-2 activity.     

Changes in the associations of race and rurality with SARS-CoV-2 infection,mortality, and case fatality in the United States from February 2020 to March 2021: A population-based cohort study

BackgroundWe examined whether key sociodemographic and clinical risk factors for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and mortality changed over time in a population-based cohort study.Methods and findingsIn a cohort of 9,127,673 persons enrolled in the United States Veterans Affairs (VA) healthcare system, we evaluated the independent associations of sociodemographic and clinical characteristics with SARS-CoV-2 infection (n = 216,046), SARS-CoV-2–related mortality (n = 10,230), and case fatality at monthly intervals between February 1, 2020 and March 31, 2021. VA enrollees had a mean age of 61 years (SD 17.7) and were predominantly male (90.9%) and White (64.5%), with 14.6% of Black race and 6.3% of Hispanic ethnicity. Black (versus White) race was strongly associated with SARS-CoV-2 infection (adjusted odds ratio [AOR] 5.10, [95% CI 4.65 to 5.59], p-value <0.001), mortality (AOR 3.85 [95% CI 3.30 to 4.50], p-value < 0.001), and case fatality (AOR 2.56, 95% CI 2.23 to 2.93, p-value < 0.001) in February to March 2020, but these associations were attenuated and not statistically significant by November 2020 for infection (AOR 1.03 [95% CI 1.00 to 1.07] p-value = 0.05) and mortality (AOR 1.08 [95% CI 0.96 to 1.20], p-value = 0.21) and were reversed for case fatality (AOR 0.86, 95% CI 0.78 to 0.95, p-value = 0.005). American Indian/Alaska Native (AI/AN versus White) race was associated with higher risk of SARS-CoV-2 infection in April and May 2020; this association declined over time and reversed by March 2021 (AOR 0.66 [95% CI 0.51 to 0.85] p-value = 0.004). Hispanic (versus non-Hispanic) ethnicity was associated with higher risk of SARS-CoV-2 infection and mortality during almost every time period, with no evidence of attenuation over time. Urban (versus rural) residence was associated with higher risk of infection (AOR 2.02, [95% CI 1.83 to 2.22], p-value < 0.001), mortality (AOR 2.48 [95% CI 2.08 to 2.96], p-value < 0.001), and case fatality (AOR 2.24, 95% CI 1.93 to 2.60, p-value < 0.001) in February to April 2020, but these associations attenuated over time and reversed by September 2020 (AOR 0.85, 95% CI 0.81 to 0.89, p-value < 0.001 for infection, AOR 0.72, 95% CI 0.62 to 0.83, p-value < 0.001 for mortality and AOR 0.81, 95% CI 0.71 to 0.93, p-value = 0.006 for case fatality). Throughout the observation period, high comorbidity burden, younger age, and obesity were consistently associated with infection, while high comorbidity burden, older age, and male sex were consistently associated with mortality. Limitations of the study include that changes over time in the associations of some risk factors may be affected by changes in the likelihood of testing for SARS-CoV-2 according to those risk factors; also, study results apply directly to VA enrollees who are predominantly male and have comprehensive healthcare and need to be confirmed in other populations.ConclusionsIn this study, we found that strongly positive associations of Black and AI/AN (versus White) race and urban (versus rural) residence with SARS-CoV-2 infection, mortality, and case fatality observed early in the pandemic were ameliorated or reversed by March 2021.

George Ioannou and co-workers study the distribution of SARS-CoV-2 infections and outcomes among the United States population.     

Effects of maternal and embryo characteristics on post-fertilization provisioning in fishes of the genus <Emphasis Type="Italic">Gambusia</Emphasis>

Maternal provisioning of embryos in Gambusia (Poeciliidae) entails both production of large, yolky eggs and mother-to-embryo transfer of nutrients, the latter of which is readily quantified using injection of radiolabeled nutrients. We assayed patterns of nutrient transfer in broods of 26 Gambusia geiseri and 23 Gambusia affinis females, using injection of tritiated leucine. We examined maternal and embryo characteristics affecting the instantaneous rate of transfer and characterized the pattern of transfer to individual embryos within broods. Maternal (female size and condition) and brood characteristics (mean embryo size, developmental stage, brood size) did not predict the mean level of nutrient transfer to embryos in a brood for either species. Within broods, individual provisioning of embryos was not related to developmental stage, but was related to embryo mass in G. affinis with nutrient transfer higher to larger embryos. In addition, overall within-brood variation in nutrient transfer, measured as coefficient of variation in embryo radioactivity, was higher in G. affinis than in G. geiseri.     

Virulence and fitness of the fungal pathogen Entomophaga maimaiga in its host Lymantria dispar, for pathogen and host strains originating from Asia, Europe, and North America

In this study, we tested (1) whether non-North American gypsy moth strains are susceptible to North American isolates of Entomophaga maimaiga and (2) the potential for erosion in the efficacy of E. maimaiga in controlling gypsy moth. We used bioassays to assess the variability in virulence (measured as time to death) as well as fitness of the pathogen (measured as spore production) in four gypsy strains challenged with six E. maimaiga isolates, using host and pathogen strains originating from Asia, Europe, and North America. We found that all E. maimaiga isolates tested were pathogenic to all strains of Lymantria dispar, regardless of the geographical origin of the fungal isolate, with at least 86% mortality for all combinations of fungal isolate and gypsy moth strain. We therefore conclude that Asian gypsy moths are susceptible to North American strains of E. maimaiga. No significant interactions between fungal isolates and gypsy moth strains with regard to time to death were found, indicating that each fungal isolate had the same overall effect on all the gypsy moth strains tested. However, fungal isolates differed significantly with regard to virulence, with a Russian isolate being the slowest to kill gypsy moth (5.1+/-0.1 days) and a Japanese isolate being the overall fastest to kill its host (4.0+/-0.1 days). Fungal isolates also differed in fitness, with variability in types of spores produced. These differences in virulence and fitness were, however, not correlated with geographical origin of the fungal isolate. Gypsy moth strains had no or only little effect on fungal virulence and fitness. Based on our studies with laboratory-reared gypsy moth strains, erosion of successful control of gypsy moth by E. maimaiga seems unlikely.