Survival of Pronghorns in Western South Dakota

Abstract: Survival and cause-specific mortality of pronghorns (Antilocapra americana) have been well-documented in several western states and Canadian provinces. However, no information has been collected in western South Dakota, USA, where mixed-grass prairie habitats characterize rangelands. The objectives of our study were to determine survival and cause-specific mortality of adult (>18 months) and yearling (6-18 months) pronghorns and to determine monthly and summer (Jun-Aug) survival for neonatal (<1 month of age) pronghorns in South Dakota. We radiocollared 93 adult female and 142 neonatal pronghorns on 3 areas in western South Dakota. We used bed sites from initial neonate captures to collect microhabitat information throughout Harding and Fall River counties. We measured vegetation understory and overstory height, shrub canopy, and distance to nearest concealment cover to the nearest centimeter inside 1-m² quadrats by collecting measurements at 15 random points within a 30-m radius of the bed site. We documented that coyote (Canis latrans) predation was the primary cause of mortality for neonates in western South Dakota and that microhabitat characteristics at neonate bed sites differed between northwestern and southwestern South Dakota. More intensive aerial predator control may increase neonate survival in Fall River County. Management of rangelands by state and federal employees throughout western South Dakota and Wind Cave National Park that maximizes height of overstory and understory vegetation would provide neonates with adequate concealment cover for protection from predators, thereby increasing 4-week and 12-week postcapture survival. Our study provides South Dakota game managers with region-specific, annual and seasonal survival rates that were previously only estimated, thus improving the accuracy of simulated pronghorn population model output. Hunting was the primary cause of mortality (26%) for adult females in Harding and Fall River counties, thereby confirming the continued use of annual harvest by South Dakota game managers as the primary management tool for maintaining pronghorn populations within statewide population management goals.     

Golgi Apparatus Mediated Polysaccharide Secretion by Outer Root Cap Cells of Zea mays. III. Control by Exogenous Sugars

Sugars supplied to germinating seedlings of maize (Zea mays L.) regulate the secretion of polysaccharides by the outer cells of the root cap. The polysaccharide secreted by these cells adheres to the root tip as a droplet and the size of the droplet was used to quantitate polysaccharide secretion. The polysaccharide contains glucose, galacrose, and galacturonic acid residues with smaller quantities of mannose, arabinose, xylose, fucose and rhamnose. These sugars supplied to maize seedlings had marked effects on the rate of polysaccharide secretion by root tips. The effects on secretion were independent of the growth rates of the roots. Glucose, fucose and xylose increased droplet size 1.5–2 fold (as did sucrose, maltose, lacrose, fructose and ribose) whereas galactose, arabinose and galacturonic acid were inhibitory. Mannose increased dropler size 5–7 fold. The marked effect of mannose on polysaccharide secretion was due to an increased rate of secretion combined with a longer phase of extrusion of polysaccharide into the forming droplet. The effect of mannose was partially reversed by inorganic phosphate and other sugars (except for fucose which had no effect or promoted secretion in the presence of mannose). In contrast to sucrose, mannose stimulated secretion in a maize variety having a high sugar endosperm (high endogenous sugar). The results suggest that regulation of secretion by mannose is due to an alteration of normal sugar metabolism; whereas stimulation of secretion by sucrose and other sugars may be due to an increased availability of sugars for metabolism.     

Biological response of German cockroaches fed diets containing allopurinol

The acceptability of dietary allopurinol to German cockroaches, Blattella germanica (L.), was assessed. In diet choice tests between rat chow with or without 0.1% w/w allopurinol there were no significant differences in nymphal development, feeding duration, visits or consumption. The LT50 of cockroaches fed a choice of diets was 3 weeks greater (7.88) than those fed non-choice a 0.1% allopurinol diet. Female cockroaches provided a choice of diets aborted a significantly greater percentage of their oothecae (98.6%) than those fed the untreated diet (1.7%). Choice arena tests of 2% allopurinol in rat chow significantly reduced cockroach populations compared with untreated controls. After 6 weeks, populations were reduced by approximately 50%, and 97% after 14 weeks. These results indicate that allopurinol is acceptable to B. germanica as a dietary supplement which could be used in baits for cockroach control.     

Stem Cell Factor Regulates Human Melanocyte-Matrix Interactions

Stem cell factor (SCF) is hypothesized to play a critical role in the migration of melanocytes during embryogenesis because mutations in either the SCF gene, or its ligand, c-kit, result in defects in coat pigmentation in mice and in skin pigmentation in humans. In this report we directly show that SCF alters the adhesion and migration of human melanocytes to extracellular matrix (ECM) ligands and regulates integrin expression at the protein level. SCF decreased adhesion of neonatal and fetal cells to collagen IV, and increased attachment of fetal cells to laminin. Attachment of fetal cells to fibronectin was decreased, but was unchanged in neonatal cells. Flow cytometry analysis of neonatal melanocytes showed that SCF down-regulated the expression of the α2 receptor, and up-regulated the expression of the α3, α5 and β1 integrin receptors. SCF down-regulated expression of α2, α5 and β1 integrins by fetal melanocytes, and up-regulated expression of the αv and α3 integrin receptors. Analysis of melanocyte migration using time-lapse videomicroscopy showed that SCF significantly increased migration of neonatal, but not fetal, melanocytes on fibronectin (FN). We conclude that SCF regulates integrin expression at the protein level and that SCF has pleiotropic effects on melanocyte attachment and migration on ECM ligands. We suggest that this may be one mechanism by which SCF regulates melanocyte migration during development of the skin.