Interspecific Introgression in Cetaceans: DNA Markers Reveal Post-F1 Status of a Pilot Whale

Visual species identification of cetacean strandings is difficult, especially when dead specimens are degraded and/or species are morphologically similar. The two recognised pilot whale species (Globicephala melas and Globicephala macrorhynchus) are sympatric in the North Atlantic Ocean. These species are very similar in external appearance and their morphometric characteristics partially overlap; thus visual identification is not always reliable. Genetic species identification ensures correct identification of specimens. Here we have employed one mitochondrial (D-Loop region) and eight nuclear loci (microsatellites) as genetic markers to identify six stranded pilot whales found in Galicia (Northwest Spain), one of them of ambiguous phenotype. DNA analyses yielded positive amplification of all loci and enabled species identification. Nuclear microsatellite DNA genotypes revealed mixed ancestry for one individual, identified as a post-F1 interspecific hybrid employing two different Bayesian methods. From the mitochondrial sequence the maternal species was Globicephala melas. This is the first hybrid documented between Globicephala melas and G. macrorhynchus, and the first post-F1 hybrid genetically identified between cetaceans, revealing interspecific genetic introgression in marine mammals. We propose to add nuclear loci to genetic databases for cetacean species identification in order to detect hybrid individuals.     

Interaction of rat mammary gland thioesterase II with fatty acid synthetase is dependent on the presence of acyl chains on the synthetase

The interaction between rat mammary gland thioesterase II and fatty acid synthetase has been studied by a variety of physicochemical techniques. Pyrene-labeled thioesterase II does not exhibit increased fluorescence anisotropy when mixed with fatty acid synthetase, suggesting that the enzymes do not readily form a complex. Nevertheless, the functional interaction between the enzymes can be easily demonstrated by observing the hydrolysis, by unmodified thioesterase II, of acyl chains from their thioester linkage to the 4-phosphopantetheine of the fatty acid synthetase. This hydrolytic reaction is not inhibited even in the presence of a large excess of fatty acid synthetase with vacant 4'-phosphopantetheine thiols, indicating that interaction occurs only between thioesterase and fatty acid synthetase species which carry acyl chains on the 4'-phosphopantetheine thiols. A novel model system was devised which allowed us to explore the nature of the physical interaction between the two enzymes under conditions where the synthetase was actively engaged in acyl chain assembly. Fatty acid synthetase was treated with phenylmethanesulfonyl fluoride to inhibit its resident thioesterase activity, immobilized via a specific antibody to a column of Sepharose 4B, and exposed to the substrates required for acyl-enzyme assembly. When thioesterase II was introduced to the column, it passed through unretarded even though it efficiently catalyzed hydrolysis of the immobilized S-acyl synthetase en route. These results indicate that the two enzymes associate when an acyl chain is present on the synthetase and that they dissociate rapidly following completion of the catalytic process. Thus, the mammary system differs from that of the avian uropygial gland in which the two enzymes associate to form a stable complex even in the absence of substrates.     

Acyl-CoA-binding protein from cow. Binding characteristics and cellular and tissue distribution.

Hydroxyl radicals (OH.) in free solution react with scavengers at rates predictable from their known second-order rate constants. However, when OH. radicals are produced in biological systems by metal-ion-dependent Fenton-type reactions scavengers do not always appear to conform to these established rate constants. The detector molecules deoxyribose and benzoate were used to study damage by OH. involving a hydrogen-abstraction reaction and an aromatic hydroxylation. In the presence of EDTA the rate constant for the reaction of scavengers with OH. was generally higher than in the absence of EDTA. This radiomimetic effect of EDTA can be explained by the removal of iron from the detector molecule, where it brings about a site-specific reaction, by EDTA allowing more OH. radicals to escape into free solution to react with added scavengers. The deoxyribose assay, although chemically complex, in the presence of EDTA appears to give a simple and cheap method of obtaining rate constants for OH. reactions that compare well with those obtained by using pulse radiolysis.     

Misunderstanding as therapy: Doctors,patients and medicines in a rural clinic in Sri Lanka

In this paper I want to draw attention to the integration of Western medicine into therapeutic choices among patients in rural Sri Lanka. These patients' interpretation and use of Western pharmaceuticals is discussed in relation to the Ayurvedic theory of balance. The influence of this theory on people's ideas of health and illness is highlighted in encounters where laymen and professionals alike use Western medicines according to context and their respective perspectives. Such therapeutic encounters are used to describe how the meaning of therapy is negotiated and communicated. The modes of perception used by doctors and patients seem to be mutually exclusive but each has its own logic. Western medicines are used as a symbolic means which help the patients and the practitioners of Western clinical medicine in a rural health unit to communicate through — rather than despite — misunderstandings based on their differing cultural assumptions about the body, about disease and about therapy. This argument is raised in relation to recent theoretical discussions among medical anthropologists concerning doctor-patient relationships, asymmetric medical relations and the analysis of meaning systems     

The cya gene region of Erwinia chrysanthemi B374: organisation and gene products

Summary A DNA fragment containing the cya gene region of Erwinia chrysanthemi, B374 was cloned in vivo and transferred into cells of E. coli using a plasmid pULB113 derived from RP4 followed by subcloning in vitro into the vector pBR322. The cya gene encodes a 95 kDal protein that complemented E. coli cya mutants. Apparently, cya genes truncated at the 3 end could still produce proteins complementing cya-defective strains, thus showing that adenylate cyclase truncated at its carboxy-terminal end could synthesise cAMP. A protein of unknown function (40 kDal) is encoded by a gene that is transcribed divergently from the control region of the adenylate cyclase gene.     

District Nursing Sister Attached to Hospital Surgical Department

An experiment of attaching a district nursing sister to the surgical department of a general hospital was designed to show the use of the district nursing service for the after-care of patients discharged from hospital after surgical treatment. In a 15-week period about 590 bed days were saved, and only six out of 126 patients discharged early had to be readmitted. Most of the patients and the general practitioners who replied to questionaries about the scheme were in favour of it.     

Physiological factors limiting growth and yield ofOryza sativa under unflooded conditions

Summary Rice grown under flooded conditions consistently produces better vegetative growth and higher grain yields than when grown in unflooded culture. Physiological and nutritional differences in rice grown under these two conditions were determined. Growth observations showed that plants under unflooded culture made an initial vigorous start, but soon showed poor tillering, depressed leaf growth, delayed flowering, low moisture content, foliar chlorosis, and 52.6 per cent lower yield than flooded plants.Chemical analysis emphasized the higher manganese content of plants grown under unflooded culture with no significant differences in other elements. Plants grown in nutrient cultures and under field conditions gave evidence that nitrate nitrogen nutrition, as exists for plants under unflooded conditions, favored manganese accumulation.Growth responses suggest differences in auxin metabolism. Since auxins could not be estimated directly, some factors affecting auxin degradation were investigated. It was found that plants grown under unflooded conditions had: 1) a low catalase activity, and: 2) a high peroxidase activity, which favor accelerated auxin degradation. It is proposed that high manganese levels in plants grown under unflooded conditions affects the indoleacetic acid oxidase mechanism resulting in retarded growth and depressed grain yields.