Heat mediated quick Coomassie blue protein staining and destaining of SDS-PAGE gels.

For the detection of proteins on sodium dodecyl sulphate-polyacrylamide gel electrophoresis, Coomassie blue is used commonly on account of its simplicity and reliability. In this report we show that enhanced heat, in addition to dramatically decreasing the time required for staining and destaining, also significantly increased the detection sensitivity. For a 1.5 mm gel, the staining time was 5 min at 55, 62.5 or 70 degrees C while the destaining time was 45, 45 and 20 min respectively. For a 0.8 mm gel, the staining time could be reduced to 1 min at 65 degrees C compared to 2 min at 60 degrees C and 5 min at 55 degrees C. The destaining time required was 8, 15 and 20 min at the respective temperatures.     

Seasonal habitat use indicates that depth may mediate the potential for invasive round goby impacts in inland lakes

1. The round goby (Neogobius melanostomus) is among the fastest-spreading introduced aquatic species in North America and is radiating inland from the Great Lakes into freshwater ecosystems across the landscape. Predicting and managing the impacts of round gobies requires information on the factors influencing their distribution in habitats along the invasion front, yet this information is not available for many recently invaded ecosystems. We evaluated the seasonal habitat use and biomass of round gobies in an inland temperate lake to define the spatiotemporal scope of biological interactions at the leading edge of the round goby invasion.
2. Using novel statistical approaches, we combined hierarchical models that control for imperfect species detection with flexible smooth terms to describe non-linear relationships between round goby abundance and environmental gradients. Subsequently, we generated accurate detection-corrected estimates of the standing stock biomass of round gobies.
3. Our results show seasonally differentiated habitat niches, where suitable round goby habitat in summer months is restricted to shallow depths (<18.4 m) with a mixture of vegetative and mussel cover. We found high round goby biomass of 122 kg/ha in occupied habitats during the summer, with a total lake-wide biomass of 766,000 kg. In winter, round gobies migrate to deep offshore habitats and disperse, dramatically altering their scope for biological interactions with resident aquatic species across summer and winter seasons.
4. The results of this study indicate that the scope of biological interactions in inland lakes may be seasonally variable, with potential for high round goby biomass in shallow lakes or at the periphery of deep lakes in the summer months. Such shallow-water habitats may therefore present higher risk of ecological impacts from round gobies in invaded lentic ecosystems. As round gobies expand inland, consideration of seasonal habitat use will be an important factor in predicting the impacts of this pervasive invader.

     

Structure of ribosomes and ribosomal subunits of Drosophila

Summary The ultrastructure of Drosophila melanogaster cytoplasmic ribosomal subunits and monomers have been examined by electron microscopy. The Drosophila ribosomal structures are compared to those determined for other eucaryotes and E. coli. Negatively contrasted images of 60S subunits are seen in the most frequent view to be approximately round particles about 280 Å in diameter. About 35% of the particles present a single prominent projection which we call the 60S peak. The peak emanates from a flattened region of the 60S subunit. The maximum observed length of the 60S peak is approximately 90Å. The Drosophila 60S peak is highly reminiscent of the E. coli L7/L12 stalk. The Drosophila 40S subunit is an elongated, slightly bent particle which measures 280×170×160 Å. It bears a strong resemblance to small ribosomal subunits of other eucaryotes and is strikingly similar to the E. coli 30S subunit. Micrographs of 80S monomeric ribosomes show the long axis of the 40S to be parallel and in apparent contact with the flattened region of 60S subunit. The 60S peak appears to bisect the long axis of the 40S subunit. The 40S subunit seems to be oriented in the monomeric ribosome so that the 40S projection is toward the body of the large subunit. Comparison of our data with similar studies in different organisms indicates that the eucaryotic large ribosomal subunits exhibit morphological heterogeneity while the small subunits remain remarkably similar.     

Transactivation of Ds elements in plants of lettuce (Lactuca sativa)

The maize transposable element, Activator (Ac), is being used to develop a transposon mutagenesis system in lettuce, Lactuca sativa. In this paper, we describe somatic and germinal transactivation of Ds by chimeric transposase genes in whole plants. Constructs containing either the Ds element or the Ac transposase open reading frame (ORF) were introduced into lettue. The Ds element was located between either the 35S or the Nos promoter and a chimeric spectinomycin resistance gene (which included a transit peptide), preventing expression of spectinomycin resistance. The genomic coding region of the Ac transposase was expressed from the 35S promoter. Crosses were made between 104 independent R₁ plants containing Ds and three independent R₁ plants expressing transposase. The excision of Ds in F₁ progenies was monitored using a phenotypic assay on spectinomycin-containing medium. Green sectors in one-third of the F₁ families indicated transactivation of Ds by the transposase at different developmental stages and at different frequencies in lettuce plants. Excision was confirmed using PCR and by Southern analysis. The lack of green sectors in the majority of F₁ families suggests that the majority of T-DNA insertion sites are not conducive to excision. In subsequent experiments, the F₁ plants containing both Ds and the transposase were grown to maturity and the F₂ seeds screened on medium containing spectinomycin. Somatic excision was again observed in several F₂ progeny; however, evidence for germinal excision was observed in only one F₂ family.     

Effect of level of infection with Nippostrongylus brasiliensis on intestinal absorption of hexoses in rats

Transfer of glucose and galactose in vitro from the mucosal to serosal side of the entire small intestine was significantly reduced in male rats 10 days after infection with 100 or more larvae. Transfer of hexoses across the mucosa into the gut tissue by the entire intestine was generally not significantly affected by infection but transfer from the tissue to serosal fluid was significantly reduced, the reductions occurring throughout the intestine, and the metabolism of glucose significantly increased, the increases occurring in the distal two-thirds of the intestine. Females showed a reduction in serosal glucose transfer at an infection level of 50 larvae whereas males did not and the uninfected distal third of the intestine showed the same response to infection as the infected proximal third. The length of the intestine increased significantly at infection levels of 100 or more larvae.