Isolation of Vibrio parahaemolyticus from the Processed Meat of Chesapeake Bay Blue Crabs

A method for the recovery of Vibrio parahaemolyticus from seafoods is described. By this procedure, a total of 56 biochemically positive cultures of V. parahaemolyticus were recovered from market samples of Chesapeake Bay processed blue crab (cooked, picked, packed, and refrigerated meat). All of the isolates were tested serologically, and 22 strains were serotyped according to the schema of Sakazaki as follows: K3, K5, K28, K31, K36, K37, K39, K43, and K44. These results indicate the broad distribution of these specific serotypes in a seafood harvested from the Chesapeake Bay.     

Circulating progenitor epithelial cells traffic via CXCR4/CXCL12 in response to airway injury

Recipient airway epithelial cells are found in human sex-mismatched lung transplants, implying that circulating progenitor epithelial cells contribute to the repair of the airway epithelium. Markers of circulating progenitor epithelial cells and mechanisms for their trafficking remain to be elucidated. We demonstrate that a population of progenitor epithelial cells exists in the bone marrow and the circulation of mice that is positive for the early epithelial marker cytokeratin 5 (CK5) and the chemokine receptor CXCR4. We used a mouse model of sex-mismatched tracheal transplantation and found that CK5+ circulating progenitor epithelial cells contribute to re-epithelialization of the airway and re-establishment of the pseudostratified epithelium. The presence of CXCL12 in tracheal transplants provided a mechanism for CXCR4+ circulating progenitor epithelial cell recruitment to the airway. Depletion of CXCL12 resulted in the epithelium defaulting to squamous metaplasia, which was derived solely from the resident tissue progenitor epithelial cells. Our findings demonstrate that CK5+CXCR4+ cells are markers of circulating progenitor epithelial cells in the bone marrow and circulation and that CXCR4/CXCL12-mediated recruitment of circulating progenitor epithelial cells is necessary for the re-establishment of a normal pseudostratified epithelium after airway injury. These findings support a novel paradigm for the development of squamous metaplasia of the airway epithelium and for developing therapeutic strategies for circulating progenitor epithelial cells in airway diseases.     

Hypertrophic growth in cardiac myocytes is mediated by Myc through a Cyclin D2-dependent pathway

c-Myc (Myc) is highly expressed in developing embryos where it regulates body size by controlling proliferation but not cell size. However, Myc is also induced in many postmitotic tissues, including adult myocardium, in response to stress where the predominant form of growth is an increase in cell size (hypertrophy) and not number. The function of Myc induction in this setting is unproven. Therefore, to explore Myc's role in hypertrophic growth, we created mice where Myc can be inducibly inactivated, specifically in adult myocardium. Myc-deficient hearts demonstrated attenuated stress-induced hypertrophic growth, secondary to a reduction in cell growth of individual myocytes. To explore the dependence of Myc-induced cell growth on CycD2, we created bigenic mice where Myc can be selectively activated in CycD2-null adult myocardium. Myc-dependent hypertrophic growth and cell cycle reentry is blocked in CycD2-deficient hearts. However, in contrast to Myc-induced DNA synthesis, hypertrophic growth is independent of CycD2-induced Cdk2 activity. These data suggest that Myc is required for a normal hypertrophic response and that its growth-promoting effects are also mediated through a CycD2-dependent pathway.     

Degeneration of cultured cortical neurons following prolonged inactivation: molecular mechanisms

Networks of neurons express persistent spontaneous network activity when maintained in dissociated cultures. Prolonged blockade of the spontaneous activity with tetrodotoxin (TTX) causes the eventual death of the neurons. In this study, we investigated some molecular mechanisms that may underlie the activity-suppressed slow degeneration of cortical neurons in culture. Already after 3–4 days of exposure to TTX, well before the neurons die, they began to express markers that lead to their eventual death, 7–10 days later. There was a reduction in glutamate receptor (GluR2) expression, a persistent increase in intracellular calcium concentration, activation of calpain, and an increase in spectrin breakdown products. At this point, blockade of GluR2-lacking GluR1 or calpain (either with a selective antagonist or through the natural regulator of calpain, calpastatin), protected cells from the toxic action of TTX. Subsequently, mitochondria lost their normal elongated shape as well as their membrane potential. Eventually, neurons activated caspase 3 and PUMA (p53 up-regulated modulator of apoptosis ), hallmarks of neuronal apoptosis, and died. These experiments will lead to a better understanding of slow neuronal death, typical of neurodegenerative diseases.     

Differential pollinator effectiveness and importance in a milkweed (Asclepias, Apocynaceae) hybrid zone

? Premise of the study: Exceptions to the ideal of complete reproductive isolation between species are commonly encountered in diverse plant, animal, and fungal groups, but often the causative ecological processes are poorly understood. In flowering plants, the outcome of hybridization depends in part on the effectiveness of pollinators in interspecific pollen transport. In the Asclepias exaltata and A. syriaca (Apocynaceae) hybrid zone in Shenandoah National Park, Virginia, extensive introgression has been documented. The objectives of this study were to (1) determine the extent of pollinator overlap among A. exaltata, A. syriaca, and their hybrids and (2) identify the insect taxa responsible for hybridization and introgression. ? Methods: We observed focal plants of parental species and hybrids to measure visitation rate, visit duration, and per-visit pollinia removal and deposition, and we calculated pollinator effectiveness and importance. ? Key results: Visitation rates varied significantly between the 2 yr of the study. Overall, Apis mellifera, Bombus sp., and Epargyreus clarus were the most important pollinators. However, Bombus sp. was the only visitor that was observed to both remove and insert pollinia for both parent species as well as hybrids. ? Conclusions: We conclude that Bombus may be a key agent of hybridization and introgression in these sympatric milkweed populations, and hybrids are neither preferred nor selected against by pollinators. Thus, we have identified a potential mechanism for how hybrids act as bridges to gene flow between A. exaltata and A. syriaca. These results provide insights into the breakdown of prezygotic isolating mechanisms.     

Phenotypic and functional abnormalities of bone marrow-derived dendritic cells in systemic lupus erythematosus

Introduction  

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoreactive T and B cells, which are believed to be secondary to deficient dendritic cells (DCs). However, whether DC abnormalities occur during their development in the bone marrow (BM) or in the periphery is not known.