Additional Nucleotide Sequences in Precursor 16S Ribosomal RNA from <Emphasis Type="Italic">Escherichia coli</Emphasis>

MATURE 5S, 16S and 23S ribosomal RNA species present in E. coli ribosomes are the end products of complex biosyn-thetic pathways. They are formed by reduction in length, and methylation of longer RNA chains transcribed on the ribosomal RNA cistrons of E. coli DNA. While these modifications take place the ribosome structure is formed by progressive addition of ribosomal proteins and conformational changes in the resulting ribonucleoprotein precursor particles¹.     

The nature of the microbial stimulus affecting sporophore formation in Agaricus bisporus (Lange) Sing

An apparatus is described in which pure cultures of Agaricus bisporus were maintained on composted media in filtered atmospheres free from (a) noxious concentrations of carbon dioxide, and (b) contaminating microorganisms. When grown on compost alone, cultures of A. bisporus did not produce sporophores. Their formation was however stimulated by a covering layer of an unsterilized mixture of peat and chalk (=‘casing’ soil). Autoclaving or fumigating ‘casing’ with propylene oxide decreased populations of contaminating bacteria and prevented sporophore formation. Populations of micro-organisms isolated from unsterile ‘casing’ contained bacteria which when added to pure cultures of A. bisporus stimulated fruit-body formation. Numbers of these stimulators increased when cultured on a carbon-free liquid medium exposed to atmospheres with ethanol, ethyl acetate and acetone or containing the volatile metabolites of A. bisporus. The ability to utilize these volatile chemicals was exploited in a selective technique for isolating sporophore stimulators where aqueous suspensions of mixed bacterial populations were exposed to atmospheres of these materials for 5 days, before aliquots were added to agar media subsequently gelled. The stimulatory bacteria were identified as, or closely related to, Pseudomonas putida.     

Selective inhibition of prostaglandin biosynthesis by gold salts and phenylbutazone

Gold salts and phenylbutazone selectively inhibit the synthesis of PGF_2α and PGE₂ respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE₂ and PGF_2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function.     

Two silicone nontoxic fouling release coatings: Hydrosilation cured PDMS and CaCO3 filled,ethoxysiloxane cured RTV11

Two silicone coatings have been evaluated for barnacle adhesion. One coating is an unfilled hydrosilation cured polydimethylsiloxane (PDMS) network, while the other is a room temperature vulcanized (RTV), filled, ethoxysiloxane cured PDMS elastomer, RTV11^?. The adhesion strength of one species of barnacle, Balanus eburneus, to the hydrosilation coatings is in the range of 0.37–0.60 kg cm^‐2 while the corresponding range for RTV11 is 0.64–0.90 kg cm^‐2. The easier release of B. eburneus from the hydrosilation cured network compared to RTV11 is discussed in relationship to differences in bulk and surface properties. Preliminary results suggest bulk modulus may be the most important parameter in determining barnacle adhesion strength. In light or mechanical property analysis, a re‐evaluation of surface properties and chemical stability is presented.     

Spatial and Temporal Analysis of Contact Rates in Female White-Tailed Deer

Abstract: White-tailed deer (Odocoileus virginianus) are important game mammals and potential reservoirs of diseases of domestic livestock; thus, diseases of deer are of great concern to wildlife managers. Contact, either direct or indirect, is necessary for disease transmission, but we know little about the ecological contexts that promote intrasexual contact among deer. Using pair-wise direct contacts estimated from Global Positioning System collar locations and joint utilization distributions (JUDs), we assessed habitats in which contacts occur to test whether direct contact rates among female white-tailed deer in different social groups differs among land-cover types. We also tested whether contact rates differed among seasons, lunar phases, and times of day. We obtained locations from 27 female deer for periods of 0.5–17 months during 2002–2006. We designated any simultaneous pair of locations for 2 deer <25 m apart as a direct contact. For each season, we used compositional analysis to compare land-cover types where 2 deer had contact to available land-cover weighted by their JUD. We used mixed-model logistic regression to test for effects of season, lunar phase, and time of day on contact rates. Contact rates during the gestation season were greater than expected from random use in forest and grassland cover, whereas contact rates during the fawning period were greater in agricultural fields than in other land-cover types. Contact rates were greatest during the rut and lowest in summer. Diel patterns of contact rates varied with season, and contact rates were elevated during full moon compared to other lunar periods. Both spatial and temporal analyses suggest that contact between female deer in different social groups occurs mainly during feeding, which highlights the potential impact of food distribution and habitat on contact rates among deer. By using methods to associate contacts and land-cover, we have created beneficial tools for more elaborate and detailed studies of disease transmission. Our methods can offer information necessary to develop spatially realistic models of disease transmission in deer.