Characterization of Aerosolized Bacteria and Fungi From Desert Dust Events in Mali, West Africa

Millions of metric tons of African desert dust blow across the Atlantic Ocean each year, blanketing the Caribbean and southeastern United States. Previous work in the Caribbean has shown that atmospheric samples collected during dust events contain living microbes, including plant and opportunistic human pathogens. To better understand the potential downwind public health and ecosystem effects of the dust microbes, it is important to characterize the source population. We describe 19 genera of bacteria and 3 genera of fungi isolated from air samples collected in Mali, a known source region for dust storms, and over which large dust storms travel.     

Origins and evolution of eukaryotic RNA interference

Small interfering RNAs (siRNAs) and genome-encoded microRNAs (miRNAs) silence genes via complementary interactions with mRNAs. With thousands of miRNA genes identified and genome sequences of diverse eukaryotes available for comparison, the opportunity emerges for insights into the origin and evolution of RNA interference (RNAi). The miRNA repertoires of plants and animals appear to have evolved independently. However, conservation of the key proteins involved in RNAi suggests that the last common ancestor of modern eukaryotes possessed siRNA-based mechanisms. Prokaryotes have an RNAi-like defense system that is functionally analogous but not homologous to eukaryotic RNAi. The protein machinery of eukaryotic RNAi seems to have been pieced together from ancestral archaeal, bacterial and phage proteins that are involved in DNA repair and RNA processing.     

TRANSECTION OF THE PANCREAS BY BLUNT TRAUMA

If a diagnosis of traumatic pancreatitis is made and the patient does not improve clinically during the first 24 hours, transection of the pancreas should be suspected. If this is found to be the case at operation, the distal pancreas should be resected and the proximal end of the pancreas closed carefully with interrupted mattress suture of non-absorbable suture material. Particularly, the pancreatic duct should be ligated to prevent the formation of an external fistula. Any attempt at reapproximation of the transected pancreas will invariably result in an external pancreatic fistula if the patient survives the immediate postoperative period.     

On the effect of mechanical shocks on the congelation of subcooled plant tissues

Summary Cylindrical shells of potato tissue were slid around the bulb of a thermometer and subcooled. Attempt was then made to induce crystallization by tapping the upper end of the thermometer. Out of 122 trials 52 were successful. In a few experiments, 15 repeated taps were ineffective. There is absolute evidence of the efficacy of tapping in some cases and of its inefficacy in others.The percentage of successful tappings increases at lower temperatures but since the percentage of spontaneous crystallizations also increases, a much larger number of determinations would be necessary to derive a relation between degree of subcooling and efficacy of tapping.No evidence was found in these experiments of the existence of discontinuous zones of lability at various degrees of subcooling.