A new member of the Nudiviridae from the Florida stone crab (Menippe mercenaria).

Menippe mercenaria, the Florida stone crab, supports an unconventional fishery across the southern USA and Caribbean that involves claw-removal and the return of de-clawed animals to the sea. We provide pathological, ultrastructural, and genomic detail for a novel hepatopancreatic, nucleus-specific virus - Menippe mercenaria nudivirus (MmNV) - isolated from M. mercenaria, captured during fisheries-independent monitoring. The virus has a genome of 99,336 bp and encodes 84 predicted protein coding genes and shows greatest similarity to Aratus pisonii nudivirus (ApNV) (<60% protein similarity and 31 shared genes of greatest similarity), collected from the Florida Keys, USA. MmNV is a member of the Gammanudivirus genus (Naldaviricetes: Lefavirales: Nudiviridae). Comparisons of virus genome size, preferred host environment, and gene number revealed no clear associations between the viral traits and phylogenetic position. Evolution of the virus alongside the diversification of host taxa, with the potential for host-switching, remain more likely evolutionary pathways.

Salinity and temperature affect the symbiont profile and host condition of Florida USA blue crabs Callinectes sapidus.

Subtropical Florida blue crabs, Callinectes sapidus, exhibit differing life history traits compared to their temperate counterparts, likely influencing symbiont infection dynamics. Little information exists for Florida C. sapidus symbiont profiles, their distribution among various habitats, and influence on crab condition. Using histopathology, genomics, and transmission electron microscopy, we describe the first symbiont profiles for Florida C. sapidus occupying freshwater to marine habitats. Twelve symbiont groups were identified from 409 crabs including ciliophorans, digenean, microsporidian, Haplosporidia, Hematodinium sp., Nematoda, filamentous bacteria, gregarine, Callinectes sapidus nudivirus, Octolasmis sp., Cambarincola sp., and putative microcell. Overall, 78% of C. sapidus were documented with one or more symbiont groups demonstrating high infection rates in wild populations. Environmental variables water temperature and salinity explained 48% of the variation in symbiont groups among Florida habitats, and salinity was positively correlated with C. sapidus symbiont diversity. This suggests freshwater C. sapidus possess fewer symbionts and represent healthier individuals compared to saltwater populations. Crab condition was examined using the reflex action mortality predictor (RAMP) to determine if reflex impairment could be linked to symbiont prevalence. Symbionts were found positively correlated with crab condition, and impaired crabs were more likely to host symbionts, demonstrating symbiont inclusion may boost predictive ability of the RAMP application. The microsporidian symbiont group had a particularly strong effect on C. sapidus reflex response, and impairment was on average 1.57 times higher compared to all other symbiont groups. Our findings demonstrate the importance of considering full symbiont profiles and their associations with a spatially and temporally variable environment to fully assess C. sapidus population health.

A refined DNA methylation detection method using MspJI coupled quantitative PCR.

DNA methylation is a highly conserved epigenetic modification with critical roles ranging from protection against phage infection in bacteria to the regulation of gene expression in mammals. DNA methylation at specific sequences can be measured by using methylation dependent or sensitive restriction enzymes coupled to semi- or quantitative PCR (MD-qPCR). This study reports a refined MD-qPCR method for detecting gain or loss of DNA methylation at specific sites through the specific use of MspJI or HpaII, respectively. By employing varying concentrations of DNA with methylation ranging from 0 to 100%, our data provide evidence that compared to HpaII, MspJI increases the sensitivity and accuracy of detecting relative DNA methylation gains by MD-qPCR. We also show that the MspJI-coupled MD-qPCR can accurately determine the percent gain in DNA methylation at the Sall4 enhancer and is more sensitive than HpaII in detecting relative gains in DNA methylation at the Oct4 proximal enhancer during embryonic stem cell (ESC) differentiation. The high specificity and sensitivity of this targeted approach increases its potential as a diagnostic tool to detect relatively smaller gains in DNA methylation at specific sites from limited amounts of sample.

Temperature correlates with annual changes in Hematodinium perezi prevalence in blue crab Callinectes sapidus in Florida, USA.

Blue crabs Callinectes sapidus were monitored biannually throughout Florida, USA, for 2 yr using a highly sensitive, quantitative polymerase chain reaction (qPCR) to determine the spatial and temporal changes in prevalence and intensity of Hematodinium perezi infections during drought years. Despite persistent drought conditions, H. perezi infections were not universally found. Overall prevalence was 25.3% (95% CI: 22.8-28.1%) in 1066 crabs sampled from 6 locations (Jacksonville, Ormond Beach, Everglades City, Tampa Bay, Steinhatchee, and Panama City) from 2011 to 2012. Presence of H. perezi was consistently highest in winter season samples, ranging from 4.2-51.1% (3 locations) in 2011, to 32-83% (5 locations) in 2012. The highest prevalence and intensities were observed in the winter samples from Everglades City. Previous studies have found that the prevalence of H. perezi in C. sapidus in temperate regions of the US East Coast shows seasonal peaks in early winter in Maryland and South Carolina and in fall and spring in Georgia. The seasonality of infections in the subtropical waters of Florida reinforces the concept that temperature is a strong factor that may override other drivers, such as drought. Seasonal H. perezi infections in Florida appear to be triggered by the parasite responding to an optimal temperature during the annual rise from the low temperature of winter when salinity is elevated. However, salinity alone is not sufficient to trigger an increase in prevalence of H. perezi in Florida.

WITHDRAWN: Perceptions of spatial patterns of proposed harvesting practices.

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