Comparative strength of the 1966 year class of striped bass, Roccus saxatilis (Walbaum), in three Virginia rivers

The age composition, as determined from scale impressions, of striped bass stocks in the James, York, and Rappahannock Rivers during the period June 1967 - March 1968 indicates a relative deficiency of the 1966 year class in the James River. Similar results are shown in samples from non-selective gear (pound nets, fyke nets), selective gear (gill nets, haul seines, hook-and-line), and routine surveys using a 30-foot semi-balloon trawl.https://scholarworks.wm.edu/vimsbooks/1133/thumbnail.jp

Bulk Viscosity, Decaying Dark Matter, and the Cosmic Acceleration

We discuss a cosmology in which cold dark-matter particles decay into relativistic particles. We argue that such decays could lead naturally to a bulk viscosity in the cosmic fluid. For decay lifetimes comparable to the present hubble age, this bulk viscosity enters the cosmic energy equation as an effective negative pressure. We investigate whether this negative pressure is of sufficient magnitude to account fo the observed cosmic acceleration. We show that a single decaying species in a flat, dark-matter dominated cosmology without a cosmological constant cannot reproduce the observed magnitude-redshift relation from Type Ia supernovae. However, a delayed bulk viscosity, possibly due to a cascade of decaying particles may be able to account for a significant fraction of the apparent cosmic acceleration. Possible candidate nonrelativistic particles for this scenario include sterile neutrinos or gauge-mediated decaying supersymmetric particles.Comment: 7 pages, 4 figure

Age Composition and Magnitude of Striped Bass Winter Gill-net Catches in the Rappahannock River, 1967-1970

The dependence of commercial fishing success on strong yearclasses of striped bass is demonstrated, using four years of catch records from a small group of cooperating gill-net fishermen. Age analysis of these Rappahannock River catches during 1969 and 1970 revealed that an approximate tripling of landings in 1970 was a result of selection for the dominant 1966 year-class.https://scholarworks.wm.edu/vimsbooks/1108/thumbnail.jp

Preliminary Results from Striped Bass Tagging in Virginia, 1968-1969

A total of 8525 striped bass, Morone saxatilis (Walbaum), were tagged and released in Virginia during 1968 and 1969. Releases were grouped in three periods: (1) 3195 in winter 1968, (2) 2439 during summer-fall 1968; and (3) 2891 in winter 1969. Streamer disc tags, employed in winter 1968, were subsequently replaced by internal anchor tags (Floy Tag No. FD-67). This substitution shortened application time and eliminated a source of bias introduced by the entanglement of disc tags in gill nets. Releases were made in the James, York, and Rappahannock rivers in all three periods. Rewards of one dollar have been paid for return of tags. Percentages of returns within tagged year-classes increased with age, indicating change in fishing mortality rates of striped bass during their initial 3 to 4-year residence in the lower Chesapeake Bay system.https://scholarworks.wm.edu/vimsbooks/1106/thumbnail.jp

Concurrent insulinoma and pancreatic adenocarcinoma: report of a rare case and review of the literature

Pancreatic adenocarcinoma is the 5th leading cause of cancer-related death in Western countries and insulinomas are rare endocrine neoplasms of the pancreas. The concurrent appearance of pancreatic adenocarcinoma and insulinoma is very rare and to the best of our knowledge has never been reported again. Herein, we present such an occurrence in a 74-year-old man. Resection of a mass in the uncinate process of the pancreas revealed pancreatic adenocarcinoma with severe desmoplastic reaction. Two years later, due to symptomatology persistence the patient was re-examined and a new 2cm mass in the uncinate process was found leading to surgery, which demonstrated a 2cm endocrine islet-cell tumor. Establishing a diagnosis in patients with insulinoma is difficult and the imaging studies still have low sensitivity and specificity except for intra-operative ultrasonography, which is the most accurate method detecting 90% of these lesions

Applying phylogenomics to understand the emergence of Shiga Toxin producing Escherichia coli O157:H7 strains causing severe human disease in the United Kingdom

Shiga Toxin producing Escherichia coli (STEC) O157:H7 is a recently emerged zoonotic pathogen with considerable morbidity. Since the serotype emerged in the 1980s, research has focussed on unravelling the evolutionary events from the E. coli O55:H7 ancestor to the contemporaneous globally dispersed strains. In this study the genomes of over 1000 isolates from human clinical cases and cattle, spanning the history of STEC O157:H7 in the United Kingdom were sequenced. Phylogenetic analysis reveals the ancestry, key acquisition events and global context of the strains. Dated phylogenies estimate the time to the most recent common ancestor of the current circulating global clone to 175 years ago, followed by rapid diversification. We show the acquisition of specific virulence determinates occurred relatively recently and coincides with its recent detection in the human population. Using clinical outcome data from 493 cases of STEC O157:H7 we assess the relative risk of severe disease including HUS from each of the defined clades in the population and show the dramatic effect Shiga toxin complement has on virulence. We describe two strain replacement events that have occurred in the cattle population in the UK over the last 30 years; one resulting in a highly virulent strain that has accounted for the majority of clinical cases in the UK over the last decade. This work highlights the need to understand the selection pressures maintaining Shiga-toxin encoding bacteriophages in the ruminant reservoir and the study affirms the requirement for close surveillance of this pathogen in both ruminant and human populations

Fenretinide mediated retinoic acid receptor signalling and inhibition of ceramide biosynthesis regulates adipogenesis, lipid accumulation, mitochondrial function and nutrient stress signalling in adipocytes and adipose tissue

Fenretinide (FEN) is a synthetic retinoid that inhibits obesity and insulin resistance in high-fat diet (HFD)-fed mice and completely prevents 3T3-L1 pre-adipocyte differentiation. The aim of this study was to determine the mechanism(s) of FEN action in 3T3-L1 adipocytes and in mice. We used the 3T3-L1 model of adipogenesis, fully differentiated 3T3-L1 adipocytes and adipose tissue from HFD-induced obese mice to investigate the mechanisms of FEN action. We measured expression of adipogenic and retinoid genes by qPCR and activation of nutrient-signalling pathways by western blotting. Global lipid and metabolite analysis was performed and specific ceramide lipid species measured by liquid chromatography-mass spectrometry. We provide direct evidence that FEN inhibits 3T3-L1 adipogenesis via RA-receptor (RAR)-dependent signaling. However, RARα antagonism did not prevent FEN-induced decreases in lipid levels in mature 3T3-L1 adipocytes, suggesting an RAR-independent mechanism. Lipidomics analysis revealed that FEN increased dihydroceramide lipid species 5- to 16-fold in adipocytes, indicating an inhibition of the final step of ceramide biosynthesis. A similar blockade in adipose tissue from FEN-treated obese mice was associated with a complete normalisation of impaired mitochondrial β-oxidation and tricarboxylic acid cycle flux. The FEN catabolite, 4-oxo-N-(4-hydroxyphenyl)retinamide (4-OXO), also decreased lipid accumulation without affecting adipogenesis. FEN and 4-OXO (but not RA) treatment additionally led to the activation of p38-MAPK, peIF2α and autophagy markers in adipocytes. Overall our data reveals FEN utilises both RAR-dependent and -independent pathways to regulate adipocyte biology, both of which may be required for FEN to prevent obesity and insulin resistance in vivo