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Spermidine is a natural polyamine which was shown to prolong lifespan of organisms and to improve cardiac and cognitive function. Spermidine was also reported to reduce inflammation and modulate T-cells. Autophagy is one of the mechanisms that spermidine exerts its effect. Autophagy is vital for β-cell homeostasis and autophagy deficiency was reported to lead to exacerbated diabetes in mice. The effect of spermidine in type 1 diabetes pathogenesis remains to be elucidated. Therefore, we examined the effect of spermidine treatment in non-obese diabetic (NOD) mice, a mouse model for type 1 diabetes. NOD mice were given untreated or spermidine-treated water ad libitum from 4 weeks of age until diabetes onset or 35 weeks of age. We found that treatment with 10 mM spermidine led to higher diabetes incidence in NOD mice despite unchanged pancreatic insulitis. Spermidine modulated tissue polyamine levels and elevated signs of autophagy in pancreas. Spermidine led to increased proportion of pro-inflammatory T-cells in pancreatic lymph nodes (pLN) in diabetic mice. Spermidine elevated the proportion of regulatory T-cells in early onset mice, whereas it reduced the proportion of regulatory T-cells in late onset mice. In summary spermidine treatment led to higher diabetes incidence and elevated proportion of T-cells in pLN.

SUMMARYIn this paper, we describe the occurrence of a microsporidian parasite in female-biased populations of an intertidal amphipod,Corophium volutator(Pallas), at mudflat sites in the Bay of Fundy, Canada. Sequence data for the parasite's 16S rDNA indicate that it is a novel microsporidian species. This parasite was found principally in female host gonads, indicating that it might be a vertically transmitted, sex-distorting microparasite. At 4 sites each sampled in early and mid-summer, parasite prevalence varied from 0 to 21%. In the lab, infected mothers gave rise to more female-biased broods, than did uninfected mothers. Infection was not associated with size of females or with lowered survivorship of their young. Surprisingly, infected mothers actually had higher fertility controlling for body length than did uninfected mothers. Taken together, our results suggest that this novel microsporidian is likely a feminizing microparasite and is a contributing factor to local and widespread sex ratio distortion inC. volutator.

Potential rates of reproduction (PRR) differ between the sexes of many animal species. Adult sex ratios together with PRR are expected to determine the operational sex ratio (OSR) defined as the ratio of fertilizable females to sexually active males at any given time. OSR is expected to determine the degree to which one sex competes for another—the limiting sex. We explored the potential for mate limitation in an intertidal amphipod, Corophium volutator (Pallas). Males have higher PRR than females, but males may be limiting because of extreme female-biased sex ratios observed in this species. Consistent with this idea, late season females were less likely to be ovigerous and had smaller size-specific clutches, both of which were associated with seasonal declines in availability of males of reproductive size. Seasonal changes in ovigery could not be explained by seasonal changes across sites in other factors (e.g., female body size or phenology of breeding). Smaller females were less likely to become ovigerous later in the season at three of four sites. Seasonal reductions in clutch size also occurred among small females expected to be reproducing for their first time. In complimentary laboratory experiments, reduced likelihood of ovigery and reduced fecundity occurred when the number of receptive females was increased relative to availability of a reproductively active male. Our results suggest male mate limitation can occur seasonally in this species and that male limitation is regionally widespread and may affect recruitment.

We studied feeding site selection and impacts by benthic fish (flounder and skates) on the amphipod Corophium volutator, an ecologically-important species in muddy intertidal communities. We determined that benthic fish foraged mainly in areas that had high densities of amphipods, on a mudflat in Nova Scotia, Canada. This observation was based on recording sediments displaced by benthic fish in areas where samples of amphipods also were taken. From gut-content analysis, we found that benthic fish fed almost entirely on C. volutator, and most consumed smaller amphipods than expected based on samples of amphipods collected from the substrate. Benthic fish also fed on male amphipods more than expected. We determined that daily foraging pressure by benthic fish on amphipods was low (about 0.3% per day) by measuring the new appearance of feeding traces made by fish. Nonetheless, fish are expected to have substantial impacts on demography of C. volutator due to the length of the fish foraging season an...

We investigated the functional significance of intersexuality in the amphipod Corophium volutator, a key species in soft-bottom intertidal communities. Intersexes in this species possess morphological and anatomical characters of both males and females. Two broad types of intersexes were identified: those with nonsetose oostegites and two penial papillae (Type I), and those with setose oostegites and one or two penial papillae (Type II). We found little evidence that intersexes function as females, but some females housed experimentally with intersexes became ovigerous, indicating that intersexes can function as males. Females that mated with Type II intersexes produced smaller broods than those that mated with Type I intersexes or males, suggesting that this form of intersexuality may be costly to amphipods (most Type II intersexes possessed only a single testis). Male function of intersexes may be important in populations of C. volutator because males are frequently the limiting sex due to extr...

Trichoderma spp. are used extensively in industry and are routinely disposed of in landfill sites as spent biomass from fermentation plants. However, little is known regarding the environmental fate of this biomass. We tracked the survival of T. reesei strain QM6A#4 (a derivative of strain QM6A marked with a recombinant construct) over a 6-month period in laboratory-contained, intact soil-core microcosms incubated in a growth chamber. Survival was tested in 3 different soils and the effect of a plant rhizosphere (bush lima beans, Phaseolus limensis) was investigated. Levels and viability of the fungus were determined, respectively, by quantitative competitive polymerase chain reaction analysis of total soil DNA extracts and dilution-plating of soil on a semiselective growth medium. Whereas chemically killed QM6A#4 became undetectable within 3 d, QM6A#4 added as a live inoculum decreased ~4- to ~160-fold over the first 1–3 months and then reached a steady state. After 4 months, soil cores were subjected to a 1.5-month simulated winter period, which did not significantly affect QM6A#4 levels. Throughout the experiment, QM6A#4 remained viable. These results indicate that, following release into the environment, live T. reesei will persist in soil for at least 2 seasons.Key words: competitive PCR, genetically engineered microorganisms (GEMs), genetically modified organism (GMO), survival of microorganisms, microcosm, Trichoderma.