Some observations upon the relationship of microhaematocrit values to haemoglobin concentrations and erythrocyte numbers in the carp Cyprinus carpio L. and brook trout Salvelinus fontinalis (Mitchill)*

Simultaneous determinations of microhaematocrit, erythrocyte numbers and haemoglobin concentrations have been obtained for samples of carp and trout of both sexes acclimated to various temperature regimes, and varying seasonal and nutritional states. Because haematological parameters have been used as indices of physiological condition in fishes correlational and multivariant regression analyses were carried out in an effort to determine whether valid correlations existed between the readily-determined parameter, microhaematocrit, and the other 2 variables. Results obtained indicate that microhaematocrit can be used as a general index of haematological status in the carp but not the brook trout.     

The respiratory chain of anaerobically grown Escherichia coli: reactions with nitrite and oxygen

The reactions of nitrite and oxygen with the cytochrome d oxidase of Escherichia coli were studied, following growth of cells on glycerol with fumarate as respiratory oxidant. Optical difference spectroscopy was used to investigate the kinetics of product formation during the reaction of the respiratory chain with nitrite. Two kinetically distinct species were formed in the reaction with nitrite; these had spectral features at 438 nm and 630 nm. These observations indicate that the cytochrome d does not contribute significantly to absorbance in the Soret region, and that changes elicited by ligand binding in the Soret region are largely attributable to haemoprotein b-590. Inhibition of respiratory oxidase activity by nitrite was also investigated. The inhibition was competitive with oxygen (Ki 0.83 mM, pH 7), which allowed analysis of the reaction of the oxidase with oxygen itself. The reaction with oxygen was cooperative with an apparent number of oxygen-binding sites, n, of 1.26 at pH 7, increasing to 1.72 at pH 6. We propose a model for the oxidase in which there are two ligand-binding sites.     

The digestive tract of the whiteback griffon vulture and its role in disease transmission among wild ungulates.

The digestive tract of the whiteback vulture (Gyps africanus) is described. Some disease organisms were fed to a captive bird to discover if they could survive passage through the tract, and the role of these scavenging birds in the spread of diseases among wild ungulates is discussed.     

Quantitative comparisons ofin situ microbial biodiversity by signature biomarker analysis

Microscopic examinations have convinced microbial ecologists that the culturable microbes recovered from environmental samples represent a tiny proportion of the extant microbiota. Methods for recovery and enzymatic amplification of nucleic acids from environmental samples have shown that a huge diversity existsin situ, far exceeding any expectations which were based on direct microscopy. It is now theoretically possible to extract, amplify and sequence all the nucleic acids from a community and thereby gain a comprehensive measure of the diversity as well as some insights into the phylogeny of the various elements within this community. Unfortunately, this analysis becomes economically prohibitive if applied to the multitude of niches in a single biome let alone to a diverse set of environments. It is also difficult to utilize PCR amplification on nucleic acids from some biomes because of coextracting enzymatic inhibitors. Signature biomarker analysis which potentially combines gene probe and lipid analysis on the same sample, can serve as a complement to massive environmental genome analysis in providing quantitative comparisons between microniches in the biome under study. This analysis can also give indications of the magnitude of differences in biodiversity in the blome as well as provide insight into the phenotypic activities of each community in a rapid and cost-effective manner. Applications of signature lipid biomarker analysis to define quantitatively the microbial viable biomass of portions of an Eastern USA deciduous forest, are presented.     

Use of labelled methionine to investigate the contribution of muscle proteins to egg production in zebra finches

Many bird species show a loss of female muscle mass at the time of egg formation. In this study we investigated whether there was a causal link between the loss in muscle condition and the formation of egg proteins by feeding ³⁵S-methionine to female zebra finches to label muscle proteins. When these birds subsequently bred the isotope was transferred to the egg proteins: isotope loss from female muscle tissue was significantly greater in birds which had bred than in control groups which had not.