We examined lifetime clutch production and size at maturity for blue crabs Callinectes sapidus Rathbun in North Carolina, USA. Female crabs were collected at terminal molt and confined individually in the field for the duration of their lifetime. Crabs were monitored weekly for the presence of eggs. Clutch quality and larval viability were assessed for each clutch. Crabs produced up to 7 clutches over 1 to 2 spawning seasons and survived up to 394 d after the terminal molt. Time to first clutch and time between clutches were positively correlated with carapace width and best described by degree-days, physiological time calculated as a thermal integral. Size at maturity was negatively correlated with water temperature on the day of the terminal molt. Egg lipid content (mean = 79.2% of dry mass), egg diameter (mean = 267.5 µm), larval carapace width (mean = 278.4 µm), and larval survival time without food (mean = 3.4 d) were similar for all clutches. The percentage of embryos developing normally decreased 40% from Clutch 1 to 4, and clutch volume decreased 50% from Clutch 1 to 5. Thus, most of a crab's reproductive output is from the first few clutches. Realistic estimates of fecundity and reproductive potential are essential for accurate spawning stock assessment and population modeling. KEY WORDS: Blue crab · Callinectes sapidus · Reproductive potential · Spawning biology · Fecundity · Multiple clutches · Degree-days Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 394: [153][154][155][156][157][158][159][160][161][162][163] 2009 serves to reduce the risk of predation and sperm competition (Jivoff 1997). Thus, the duration of the postcopulatory embrace depends on the presence of conspecific predators, sex ratio, and male size and density (Jivoff 1997). Approximately 12% of females mate with at least a second male (Jivoff 1997). Females mate only following the terminal molt (Van Engel 1958); thus, all clutches produced by a female must be fertilized by stored sperm. Sufficient sperm is stored to fertilize up to a dozen clutches of eggs . Wolcott et al. (2005) found that the number and viability of sperm transferred during mating are independent of male and female body size. Female crabs then forage, develop mature ovaries, extrude a first clutch, and undertake a seaward spawning migration (Van Engel 1958, Tankersley et al. 1998, Turner et al. 2003, Forward et al. 2005) using both ebb-tide transport and directed walking during flood tides (Forward et al. 2003. Spawning females produce multiple clutches, and migratory behavior continues between clutches, ensuring that spawning females are continually moving seaward throughout the spawning season , Forward et al. 2005.Studies of crab and lobster reproductive potential have traditionally examined fecundity for only a single clutch (e.g. Pillay & Nair 1971, Hines 1982, Campbell & Robinson 1983, Jones & Simons 1983, Dugan et al. 1994, Medina Mantelatto & Fransozo 1997, presumably due to the difficulty of obser...
Chronic inflammation is a common feature of obesity with elevated cytokines such as Interleukin-1 (IL-1) in circulation and tissues. Here, we report an unconventional IL-1R-MyD88-IRAK2-PHB/OPA1 signaling axis that reprograms mitochondrial metabolism in adipocytes to exacerbate obesity. IL-1 induced recruitment of IRAK2-Myddosome to mitochondria outer membrane via recognition by TOM20, followed by TIMM50-guided translocation of IRAK2 into mitochondria inner membrane to suppress oxidative phosphorylation and fatty acid oxidation, thereby, attenuating energy expenditure. Adipocyte-specific MyD88 or IRAK2 deficiency reduced high fat diet (HFD)-induced weight gain, increased energy expenditure and ameliorated insulin resistance, associated with a smaller adipocyte size and increased cristae formation. IRAK2 kinase inactivation also reduced HFD-induced metabolic diseases. Mechanistically, IRAK2 suppressed respiratory super-complex formation via interaction with PHB1 and OPA1 upon stimulation of IL-1. Taken together, our results suggest that IRAK2 Myddosome functions as a critical link between inflammation and metabolism, representing a novel therapeutic target for patients with obesity.
ObjectiveBreakthroughs in HIV treatment, especially combination antiretroviral therapy (ART), have massively reduced AIDS-associated mortality. However, ART administration amplifies the risk of non-AIDS defining illnesses including obesity, diabetes, and cardiovascular disease, collectively known as metabolic syndrome. Initial reports suggest that ART-associated risk of metabolic syndrome correlates with socioeconomic status, a multifaceted finding that encompasses income, race, education, and diet. Therefore, determination of causal relationships is extremely challenging due to the complex interplay between viral infection, ART, and the many environmental factors.MethodsIn the current study, we employed a mouse model to specifically examine interactions between ART and diet that impacts energy balance and glucose metabolism. Previous studies have shown that high-fat feeding induces persistent low-grade systemic and adipose tissue inflammation contributing to insulin resistance and metabolic dysregulation via adipose-infiltrating macrophages. Studies herein test the hypothesis that ART potentiates the inflammatory effects of a high-fat diet (HFD). C57Bl/6J mice on a HFD or standard chow containing ART or vehicle, were subjected to functional metabolic testing, RNA-sequencing of epididymal white adipose tissue (eWAT), and array-based kinomic analysis of eWAT-infiltrating macrophages.ResultsART-treated mice on a HFD displayed increased fat mass accumulation, impaired glucose tolerance, and potentiated insulin resistance. Gene set enrichment and kinomic array analyses revealed a pro-inflammatory transcriptional signature depicting granulocyte migration and activation.ConclusionThe current study reveals a HFD-ART interaction that increases inflammatory transcriptional pathways and impairs glucose metabolism, energy balance, and metabolic dysfunction.
Reactive oxygen species (ROS) are commonly produced by algal, vascular plant, and animal cells involved in the innate immune response as cellular signals promoting defense and healing and/or as a direct defense against invading pathogens. The production of reactive species in macroalgae upon injury, however, is largely uncharacterized. In this study, we surveyed 13 species of macroalgae from the Western Antarctic Peninsula and show that the release of strong oxidants is common after macroalgal wounding. Most species released strong oxidants within 1 min of wounding and/or showed cellular accumulation of strong oxidants over an hour post-wounding. Exogenous catalase was used to show that hydrogen peroxide was a component of immediate oxidant release in one of five species, but was not responsible for the entire oxidative wound response as is common in vascular plants. The other component(s) of the oxidant cocktail released upon wounding are unknown. We were unable to detect protein nitration in extracts of four oxidant-producing species flash frozen 30 s after wounding, but a role for reactive nitrogen species such as peroxynitrite cannot be completely ruled out. Two species showed evidence for the production of a catalase-activated oxidant, a mechanism previously known only from the laboratory and from the synthetic drug isoniazid used to kill the human pathogen Mycobacterium tuberculosis. The rhodophyte Palmaria decipiens, which released strong oxidants after wounding, also produced strong oxidants upon grazing by a sympatric amphipod, suggesting that oxidants are involved in the response to grazing.
Harvest restrictions by sex or reproductive status are used to protect many spawning stocks. In most U.S. states, fishery regulations for blue crabs Callinectes sapidus require release of ovigerous crabs. Ovigerous crabs caught in pots become stressed by capture and physically damage the egg mass and remove eggs. We conducted a survey to assess the extent of egg mass damage in pot‐caught crabs as well as crabs caught by hand and not subjected to pot stress. Egg mass damage was more prevalent in pot‐caught crabs (>45% during all months) than in crabs caught by hand (<6% during all months). We investigated the postcapture survival, reproductive output, and larval viability of crabs with varying amounts of egg mass damage by collecting ovigerous crabs from the pot fishery and confining them in the field for the duration of their lifetimes. Over 80% of the crabs survived to release the clutch present at capture, and crabs produced up to six clutches of eggs. Of 156 clutches produced in confinement, only 1 was damaged. Crabs confined individually and fed do not experience the stress that causes egg mass damage in pots. The lipid content of early‐stage eggs (77.0 ± 1.3% [mean ± SE]), larval carapace width (269.0 ± 3.34 μm), and larval survival time without food (3.0 ± 0.11 d) were similar for all clutches and levels of egg mass damage. Clutch volume decreased by approximately 20% with each subsequent clutch, and the percentage of embryos developing normally decreased from 97 ± 0.6% for clutch 1 to 79 ± 10.8% for clutch 5. Immediate release of ovigerous crabs could be a viable management strategy, but it would have severe economic consequences for fishermen in high‐salinity areas. Area closures, combined with subsidies for crabbers during critical times, may be the most viable management strategy until crab populations recover from current diminished levels.
Accurate assessment of the spawning stock should be important in informing fisheries management decisions. The life history and behavior of blue crabs (Callinectes sapidus) makes assessment of the spawning stock complex. In North Carolina, female blue crabs undergo their terminal molt and mate from March through November. After a variable amount of time, their ovaries mature and they extrude their first clutch of eggs. Crabs that mature in the upper estuary move from low salinity (<20 ppt) to high salinity (>22 ppt) to release their first clutch of eggs. Crabs in good habitat then forage and produce subsequent clutches of eggs, continuing to move seaward with each subsequent clutch. Thus, at any particular location, different spawning crabs will be seen each month and will build up in high salinity areas in the sounds and in the coastal ocean. The spawning population peaks in number in August/ September with some crabs releasing their first clutch and others releasing their second or higher clutch. Using blue crab bycatch data from Division of Marine Fisheries monthly gill net surveys may be helpful in estimating blue crab spawning stock. Gill net data show the monthly pattern of spawning stock movement from low to high salinity and the
Reactive oxygen species (ROS) produced by an oxidative burst are an important component of the wound response in algae, vascular plants, and animals. In all taxa, ROS production is usually attributed solely to a defense-related enzyme like NADPH-oxidase (Nox). However, here we show that the initial, wound-induced oxidative burst of the kelp Saccharina latissima depends on light and photosynthetic electron transport. We measured oxygen evolution and ROS production at different light levels and in the presence of a photosynthetic inhibitor, and we used spin trapping and electron paramagnetic resonance as an orthogonal method. Using an in vivo chemical probe, we provide data suggesting that wound-induced ROS production in two distantly related and geographically isolated species of Antarctic macroalgae may be light dependent as well. We propose that electron transport chains are an important and as yet unaddressed component of the wound response, not just for photosynthetic organisms, but for animals via mitochondria as well. This component may have been obscured by the historic use of diphenylene iodonium, which inhibits not only Noxes but also photosynthetic and respiratory electron transport as well. Finally, we anticipate physiological and/or ecological consequences of the light dependence of macroalgal wound-induced ROS since pathogens and grazers do not disappear in the dark.
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