Co-occurrence of hippopodiid siphonophores and their potential prey

It is a truism that the distribution of a predator should reflect that of its potential prey, but this is not well established for marine plankton communities. Purcell (1981) found that many siphonophore species were selective feeders and that one, Hippopodius hippopus, fed exclusively on ostracods. Pugh (1986) speculated that if such a dietary specificity also applied to other hippopodiid species, then a distributional relation between them and ostracods might be expected. This premise is examined using data from Discovery stations in the N.E. Atlantic Ocean. A clear relation is found between the abundance of ostracods and hippopodiids, while copepods have a better relation with other calycophoran siphonophores.     

Correlation of enzyme activities with fluorescence anisotropy of dansyl-labeled cytochrome b5/NADH-cytochrome-b5 reductase systems in phosphatidylcholine vesicles

The changes in steady-state fluorescence lifetimes and anisotropy decay parameters, as well as enzyme activities, of dansyl-labeled cytochrome b5 (DNS-cytochrome b5), on interaction with NADH-cytochrome-b5 reductase in DMPC vesicles, have been measured as a function of temperature. Steady-state fluorescence of DNS-cytochrome b5 in DMPC vesicles with and without cholesterol was increased on interaction with reductase at temperatures both above and below the DMPC phase transition. In all systems three fluorescence decay components of the dansyl label in DNS-cytochrome b5 were observed. In the reductase-containing system, the long (major) decay time component of DNS-cytochrome b5 and the fraction of the total fluorescence associated with this component increased over the temperature range 15-30 degrees C. In time-resolved anisotropy measurements, the order parameters of DNS-cytochrome b5 in DMPC vesicles increased on interaction with reductase at temperatures above the DMPC phase transition, and this increase was even more pronounced in cholesterol-containing vesicles, at temperatures from 15-30 degrees C. The enzyme activity of the DNS-cytochrome-b5 reductase system in DMPC vesicles was also greatly increased in the presence of cholesterol. These results show that interaction of vesicle-bound DNS-cytochrome b5 and NADH-cytochrome-b5 reductase leads to an increased degree of order of the dansyl-labeled cytochrome with little change in its rotational flexibility, and suggests that the increased order can be correlated with increased enzyme activity.     

THE CONTAMINATION OF BIRDS' FEATHERS BY FUNGI

Fungi have regularly been recorded on feathers removed from birds. Cellulose-decomposing spores which are merely carried on the feathers were common on birds sampled in Britain, but were fewer than expected on the basis of random distribution on birds sampled in India. Hyaline-spored fungi were less common on Indian birds, and more abundant on British birds than expected. Keratinophilic fungi, which are related to the dermatophytes, were particularly associated with related groups of birds: thus Turdus spp. regularly yielded Arthroderma curreyi, and partridges were contaminated with Ctenomyces serratus. Chrysosporium spp. were widespread on birds in India and Britain. Where associations have been shown, feather fats from these birds stimulate, or do not depress the growth of the keratinophilic fungi. Otherwise, feather fats were inhibitory to the fungi. The temperature relationships of the fungi, showing no growth at 40°C, would explain the restriction of the keratinophilic fungi to the outer, contour feathers, and of dermatophytes mainly to the non-insulated parts of the birds' surface.     

Regulation of thymidine metabolism in Neurospora crassa.

The utilization of thymidine by Neurospora crassa is initiated by the pyrimidine deoxyribonucleoside 2'-hydroxylase reaction and the consequent formation of thymine and ribose. Thymine must then be oxidatively demethylated by the thymine 7-hydroxylase and uracil-5-carboxylic acid decarboxylase reactions. This article shows that the 2'-hydroxylase reaction can be regulated differently than the oxidative demethylation process and suggests that the 2'-hydroxylase has, in addition to the role of salvaging the pyrimidine ring, the role of providing ribose not only for the utilization of the demethylated pyrimidine but also for other metabolic processes. One way that this difference in regulation was observed was with the uc-1 mutation developed by Williams and Mitchell. The present communication shows that this mutation increases the activities of the 7-hydroxylase and the decarboxylase but has no comparable effect on the 2'-hydroxylase. Qualitatively similar effects on these enzymes were bought about by growth of wild-type Neurospora in media lacking ammonium ion, such as the Westergaard-Mitchell medium. The 2'-hydroxylase and 7-hydroxylase are also differently affected by the carbon dioxide content of the atmosphere above the growing culture and the growth temperature. Studies with inhibitors indicated that the carbon dioxide effect is dependent on protein synthesis.     

A seasonal study of the distributions of surface state variables in Liverpool Bay. II. Nutrients

Distributions of dissolved inorganic nitrate, phosphate, and silicate observed in the surface waters of Liverpool Bay during a seasonal cycle of cruises in 1975 are presented. Winter distributions were influenced by the proportion of waters from various sources, their chemistry, and the mode of circulation, all of which were temporally variable. Non-winter distributions were additionally influenced by in situ biological activity. Principal component analysis provided a preliminary means of separating and assessing the relative importance of these factors and depicting the centres of biological activity during the non-winter cruises. Different circulation modes in January and December produced distributions with little visual similarity, and patchy nutrient distributions accompanied the spring and autumn phytoplankton blooms. Nitrogen-rich industrial and domestic effluents modified the nutrient availability ratios in the receiving waters so that silicon limited diatom growth over large areas of the Bay in spring. Nitrogen became ‘bio-limiting’ in summer and autumn. The direction of the surface residual circulation before the spring bloom is proposed as the major influence governing subsequent nutrient distributions and phytoplankton populations.     

Effects of temperature and fungicides on Chrysosporium pannorum (Link) Hughes

C. pannorum was isolated in low frequencies and only in the colder months from untreated soil and leaves and from those treated with Captan, Dicloran and Thiram. The fungus was isolated throughout the year as the major species from Verdasan-treated substrates and it occurred with increased frequencies immediately after application of the fungicide. The abundance of C. pannorum on Verdasan-treated substrates was attributed to the ability of the fungus to utilise the fungicide rather than to the absence of faster growing competitor species. C. pannorum was shown to be a slow growing and moderately cellulolytic fungus with maximum rates of growth, germination and cellulose clearing at between 15° and 20°C. Increasing concentrations of the fungicides retarded or prevented growth and activity of the fungus. C. pannorum could grow, germinate and clear cellulose in higher concentrations of Verdasan than could other species studied. C. pannorum was more tolerant of HgCl₂ than of Verdasan. The fungus could detoxify up to 3 g/ml active ingredient of Verdasan (=120 g/ml of the formulated fungicide) in liquid culture.     

Integrative analysis of multiple gene expression profiles with quality-adjusted effect size models

Background  

With the explosion of microarray studies, an enormous amount of data is being produced. Systematic integration of gene expression data from different sources increases statistical power of detecting differentially expressed genes and allows assessment of heterogeneity. The challenge, however, is in designing and implementing efficient analytic methodologies for combination of data generated by different research groups.     

Description of the data from the Collaborative Study on the Genetics of Alcoholism (COGA) and single-nucleotide polymorphism genotyping for Genetic Analysis Workshop 14

The data provided to the Genetic Analysis Workshop 14 (GAW 14) was the result of a collaboration among several different groups, catalyzed by Elizabeth Pugh from The Center for Inherited Disease Research (CIDR) and the organizers of GAW 14, Jean MacCluer and Laura Almasy. The DNA, phenotypic characterization, and microsatellite genomic survey were provided by the Collaborative Study on the Genetics of Alcoholism (COGA), a nine-site national collaboration funded by the National Institute of Alcohol and Alcoholism (NIAAA) and the National Institute of Drug Abuse (NIDA) with the overarching goal of identifying and characterizing genes that affect the susceptibility to develop alcohol dependence and related phenotypes. CIDR, Affymetrix, and Illumina provided single-nucleotide polymorphism genotyping of a large subset of the COGA subjects. This article briefly describes the dataset that was provided.