The Relationship of Catalase Activity to the Trade-Off Between Reproduction and Lifespan in the Giant Waterbug, Belostoma flumineum

Senescence is the process by which organisms age and ultimately die. Life history theory suggests that the allocation of energy into growth and reproduction is necessarily associated with a decrease in energy available for the maintenance of the soma. Many studies have shown that early or increased rates of reproduction are often correlated with a decrease in longevity, but few studies have investigated physiological correlates to this event. Catalase is an enzyme involved in the removal of oxygen free radicals implicated in damaging cellular components that contribute to senescence. A decrease in catalase activity with age could increase the organism\u27s maintenance cost and lead to an increased rate of senescence. This study investigated the possibility that changes in catalase activity are related to the energy trade-off between reproduction and longevity in the giant waterbug, Belostoma flumineum. This species is a good model for this type of investigation because both males and females contribute a significant amount of parental investment. Waterbugs were collected as fifth instar nymphs and maintained under controlled laboratory conditions. Males and females were randomly allocated to either virgin or breeder reproductive treatments. Waterbugs were assayed for catalase activity at ages of 10, 60, 100, and 150 days. Catalase activity/ g bug was shown to increase with chronological age in male and female virgins, but not in breeders of either sex; most of this change was early in life (0-60 days). Virgin bugs also had higher catalase activity I g bug than those that were allowed to breed. This might suggest that waterbugs that breed are less protected from free radical damage than virgins, and could help explain the shortened life span of breeders relative to virgins

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

The Relationship of Catalase Activity to the Trade-Off Between Reproduction and Lifespan in the Giant Waterbug, Belostoma flumineum

Senescence is the process by which organisms age and ultimately die. Life history theory suggests that the allocation of energy into growth and reproduction is necessarily associated with a decrease in energy available for the maintenance of the soma. Many studies have shown that early or increased rates of reproduction are often correlated with a decrease in longevity, but few studies have investigated physiological correlates to this event. Catalase is an enzyme involved in the removal of oxygen free radicals implicated in damaging cellular components that contribute to senescence. A decrease in catalase activity with age could increase the organism\u27s maintenance cost and lead to an increased rate of senescence. This study investigated the possibility that changes in catalase activity are related to the energy trade-off between reproduction and longevity in the giant waterbug, Belostoma flumineum. This species is a good model for this type of investigation because both males and females contribute a significant amount of parental investment. Waterbugs were collected as fifth instar nymphs and maintained under controlled laboratory conditions. Males and females were randomly allocated to either virgin or breeder reproductive treatments. Waterbugs were assayed for catalase activity at ages of 10, 60, 100, and 150 days. Catalase activity/ g bug was shown to increase with chronological age in male and female virgins, but not in breeders of either sex; most of this change was early in life (0-60 days). Virgin bugs also had higher catalase activity I g bug than those that were allowed to breed. This might suggest that waterbugs that breed are less protected from free radical damage than virgins, and could help explain the shortened life span of breeders relative to virgins

Native and nonnative bivalve settlement: Potential competition for spatial resources in a northeast Florida estuary

Introduced species often have negative effects on native species that occupy the same habitats in the area of introduction. Habitat preferences of organisms can therefore play a large role in determining the severity of interactions such as competition or predation. Previous laboratory studies have shown that the introduced mussel species Perna viridis can decrease the settlement and early survival of the native oyster species Crassostrea virginica. Both species can often be found in the same general areas, but it is unknown whether this habitat overlap is complete, or whether there are certain locations that may act as refuges for native bivalve species. The present study investigated the settlement patterns of the introduced P. viridis and two groups of native bivalves, oysters (C. virginica and Ostrea equestris) and mussels (Ischadium recurvum, Brachidontes exustus and Geukensia demissa), to determine whether preferential settlement depths and habitats differed among the groups. Most of these groups showed significantly greater settlement on deeper substrates that were located in the main channel of the Atlantic Intracoastal Waterway of northeast Florida. While native oysters also settled in adjacent feeder creeks in fairly large numbers, settlement of P. viridis in these areas was relatively rare. In main channel locations, the overlap in settlement depth is likely to result in competition between introduced and native bivalve species, but feeder creeks may provide areas of refuge for native oysters. The spatial and temporal overlap of all three groups suggests that competition among nonnative and native bivalves may occur in nature

Quantification of Reproductive Isolating Barriers Between Two Naturally Hybridizing Killifish Species

Understanding the relative importance of various reproductive barriers to the early stages of speciation is an essential question in evolutionary biology. The closely related killifishes Fundulus heteroclitus and F. grandis occasionally hybridize in a small region in coastal Northeastern Florida showing that while barriers to reproduction exist, they are incomplete. The objective of this study was to elucidate barriers to reproduction between F. heteroclitus and F. grandis in the lab, as well as to quantify their strengths and relative contributions to reproductive isolation. Pre-zygotic (mating and fertilization) and post-zygotic (hatching) barriers were investigated by performing a variety of choice and no-choice laboratory mating experiments. Under no-choice conditions, barriers to mating had the greatest influence on hybrid production in F. grandis, whereas hatching barriers contributed to the majority of reproductive isolation in F. heteroclitus. Under choice conditions, however, pre-zygotic barriers had the greatest influence on hybrid production in both species. The total reproductive isolation that was observed in females of each species was stronger in F. heteroclitus than in F. grandis, and was nearly complete in F. heteroclitus females under choice conditions and was of moderate strength in F. grandis females. These results reveal an asymmetry in the potential gene flow between these two species, with F. grandis being more likely to hybridize than F. heteroclitus in the absence of environmental influences. No-choice backcrosses were also conducted and showed that at least some F1 hybrids are fertile. The observation that pre-zygotic barriers tend to be stronger than post-zygotic barriers in the early stages of speciation is consistent with similar studies in other organisms

Testing the relative effectiveness of traditional and non-traditional antifouling substrates on barnacle and macroalgae settlement

Due to economic impacts, there is considerable interest in determining effective methods for limiting the attachment of marine invertebrates to submerged materials. We tested the effectiveness of traditional and non-traditional coatings on materials used for boat construction to limit the settlement of barnacles and macroalgae. Substrates included fibreglass, fibreglass coated with wax, aluminium, aluminium coated with antifouling paint, aluminium coated with Vaseline®, and aluminium coated with Vaseline® mixed with cayenne pepper. Tiles of each substrate were attached to frames, placed at two sites in the Intracoastal Waterway near Jacksonville, Florida, and collected after one or two successive months in the field. Barnacles as well as macroalgae showed significantly greater settlement on fibreglass than aluminium. Each type of coating tested reduced settlement relative to controls, with the lowest overall settlement of barnacles being observed on aluminium coated with Vaseline®, both with and without the addition of cayenne pepper. © 2014 © 2014 Taylor & Francis

Testing the relative effectiveness of traditional and non-traditional antifouling substrates on barnacle and macroalgae settlement

Due to economic impacts, there is considerable interest in determining effective methods for limiting the attachment of marine invertebrates to submerged materials. We tested the effectiveness of traditional and non-traditional coatings on materials used for boat construction to limit the settlement of barnacles and macroalgae. Substrates included fibreglass, fibreglass coated with wax, aluminium, aluminium coated with antifouling paint, aluminium coated with Vaseline®, and aluminium coated with Vaseline® mixed with cayenne pepper. Tiles of each substrate were attached to frames, placed at two sites in the Intracoastal Waterway near Jacksonville, Florida, and collected after one or two successive months in the field. Barnacles as well as macroalgae showed significantly greater settlement on fibreglass than aluminium. Each type of coating tested reduced settlement relative to controls, with the lowest overall settlement of barnacles being observed on aluminium coated with Vaseline®, both with and without the addition of cayenne pepper. © 2014 © 2014 Taylor & Francis

Thermal constraints for range expansion of the invasive green mussel, Perna viridis, in the southeastern United States

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Population genetics of introduced and native populations of the green mussel, Perna viridis: Determining patterns of introduction

Genetic variation can be used to determine routes of introduction of non-native species and whether introduced populations lost variation during establishment. The present study sought to determine whether multiple, geographically isolated non-native populations of the green mussel, Perna viridis, were the product of a stepping stone expansion of a single introduction or from multiple independent introductions from the native range. Measurements of genetic variation were compared among five introduced populations and three populations from within the native range. We sequenced 650 bp of the mitochondrial gene cytochrome oxidase I from 280 samples from five introduced populations and another 190 samples from three native populations. Haplotype frequencies of all introduced populations were not significantly different from each other, but virtually all populations differed from samples taken from the native range. Measurements of genetic variation tended to suggest that introduced populations had less variation than most native populations and there was no evidence for admixture in any of the introduced populations. The genetic data and Monte Carlo simulations both provide compelling evidence of a stepping-stone pattern of introduction of P. viridis from the native range to Trinidad, and from Trinidad to other locations in the Caribbean and United States. The lack of genetic variation in introduced populations suggests that the initial introduction was relatively small and the lack of admixture suggests a single original source population. © 2012 Springer Science+Business Media B.V