New evidence fortrans-species evolution of theH-2 class I polymorphism

A serological survey using alloantisera specific for the H-2 class I antigens in Japanese wild mice,Mus musculus molossinus, revealed a high frequency of the H-2K^f antigen. This antigen has also been found in European wild mice,M. m. domesticus andM. m. musculus. In this survey, the H-2K^f antigen was characterized through the use of ten newly isolated monoclonal antibodies raised against cells of a Japanese wild mouse, and by Southern blot analysis using anH-2K locus-specific probe which hybridizes with the 3′ end of the gene. The serologically identified H-2K^f antigens revealed several minor variations in reactivities to the monoclonal antibodies. However, all the antigens examined could be clearly separated into two types with respect to the restriction fragment length polymorphism (RFLP) pattern. The first type, found together with a single, characteristic RFLP pattern, was always associated with the presence of reactivity to one particular monoclonal antibody, MS54. The second type, found to represent different RFLP patterns, is associated with the absence of reactivity to MS54. This concordance between the presence of an antigenic determinant and a particular RFLP was observed not only withinMus musculus subspecies but also in a different species:M. spretus, carrying the same antigenic determinant, gave an identical RFLP to that of the other MS54-positiveMus musculus subspecies. The data suggest that the antigenic determinant specific for MS54 is an ancient polymorphic structure which has survived the long period of diversification ofMus species (approximately 2–3 million years) without alteration, and is associated with a stable DNA structure at the 3′ end of theH-2K gene.     

Implications of power law exponent in synergy and inhibition of olfactory mixtures

An index of olfactory quantitative interaction has been definedby Laffort and Dravnieks (1982). This index is obtained by combiningthe experimental effectiveness of mixtures with the power lawexponent of the components. When its value equals 1, this meansthat the ‘apparent’ inhibitions and synergies canbe expressed only through the power law exponents of the components.This, of course, holds true when a substance is added to itself.Values less than or greater than 1 are interpreted as ‘true’inhibition and synergy respectively. In a slightly modifieddefinition, this index [called (Gamma)] has been applied totwo sets of data, (i) By using an appropriate computer program,theoretical iso-intensity curves for binary mixtures were generatedby given values of this index, the variables being the concentrations.The diversity of curves is comparable to that observed in certainpsychophysical studies (Köster, 1969). (ii) EAG responsesof honey bees to 18 binary mixtures of three reciprocal concentrationseach, have been recorded. Absence of true interaction was observedin two-thirds of cases and the results concerning the last thirdare discussed. These two sets of results illustrate the integrativestrength of the index. The present work was also presentedin a condensed form in French by Laffort et al. (1984).     

Unusual basement layer in the midgut of gammaridean Niphargus virei Chevreux (Crustacea,Amphipoda)

Summary The basement membrane of the midgut and posterior caeca epithelium in the gammaridean amphipod Niphargus virei Chevreux, 1896 is made of an unusual structure. This basal lamina, properly called basal layer, shows a dense sheet formed by a system of dense hexagonal plates connected by thin filaments. Histochemical studies and enzymatic reactions lead to the conclusion that these structures are proteinaceous, without collagenous protein, and embedded in a neutral polysaccharide matrix. The possible mechanical significance of these mesenteric structures is discussed.     

Light adaptation of bacteriorhodopsin in the presence of valinomycin and potassium. pH-dependence

In the presence of valinomycin and K⁺, bacteriorhodopsin undergoes (i) a decrease of its maximum absorbance, (ii) a blue shift of the maximum wavelength of both the light and the dark adapted forms. However (iii) a normal light adaptation is maintained and (iv) the retinal-retinal interactions are not perturbed. The role of valinomycin as a K⁺-carrier allowing a H⁺-K⁺ competition as well as the stabilization of the deprotonated Schiff-base (linking retinal to the apo-opsin) is shown and discussed.Abbreviations bR bacteriorhodopsin - CD circular dichroism - DA dark-adapted - LA light-adapted - M-412 Meta-intermediate of the bacteriorhodopsin photocycle     

ANTHEPROT: a package for protein sequence analysis using a microcomputer

A simple microcomputer package is described to make the theoreticalanalysis of protein sequences. Several methods designed to comparetwo sequences, to model proteolytic reactions and to predictthe secondary structure, the hydro-phobic/hydrophilic regionsand the potential antigenic sites of proteins have been includedin an Apple II microcomputer software. The package comprises21 programs as well as the secondary structure database of Kabschand Sander (1983). Received on November 24, 1987; accepted on March 8, 1988     

Purifications of Rat Adrenal Dopamine-β-Hydroxylase: Immunological Analysis of Its Soluble and Membrane-Bound Forms with the Use of an Antibody Raised Against the Soluble Form

Soluble and membrane-bound dopamine-beta-hydroxylases (sDBH and mDBH, respectively) from rat adrenal glands have been purified through concanavalin A-Sepharose chromatography, gel filtration, and ion-exchange high-performance chromatographies. Both sDBH and mDBH were composed by four subunits of apparent molecular weight of 75,000 and showed a native molecular weight of 300,000. This procedure has not allowed us to obtain a sufficient amount of enzyme to immunize a rabbit. A second, more rapid procedure was designed to isolate sDBH, including concanavalin A-Sepharose chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A rabbit antiserum was raised against this purified protein. The specificity of the antiserum was demonstrated by neutralization of rat adrenal gland DBH activity, labeling of rat adrenal medulla on histological sections, and, after Western blot, labeling of the 75,000-molecular-weight band in the different fractions associated with DBH activity during purification. The antiserum had a higher affinity for the sDBH denatured by sodium dodecyl sulfate than for the native protein. It had a higher affinity for sDBH than for mDBH. These results strongly suggest the presence of specific hydrophilic epitopes on the sDBH, revealing structural differences between the two hydroxylase forms. Two protein bands were stained on Western blots of crude rat adrenal gland extract. One band had an apparent molecular weight of 75,000, and the other of 82,000. Our results showed that the two proteins contained similar epitopes, an observation suggesting a close structural relationship. The higher-molecular-weight protein could be the 75,000 protein before covalent modifications and cleavage.     

Synergistic and molecular interactions between the formamidine amitraz and copper(II) sulfate,used against the mite Varroa jacobsoni O., a parasite of the honeybee Apis mellifera L.

Toxicological field assays have shown that the shock-treatment efficacy of the formamidine pesticide amitraz, used against the parasitic mite Varroa jacobsoni, is synergistically improved by the administration of copper(II) sulfate through feeding of the honeybees. Amitraz is autoxidized and this process is accompanied by chemiluminescence. The emission is enhanced in the presence of low concentrations of H₂O₂. A dose-related inhibition of the chemiluminescence by CuSO₄ was observed; consistent with the formation of copper-amitraz complexes evidenced in vitro. The results suggest the possibility that a protection of amitraz by cupric ions might be at the origin of the enhancement of its toxicity and thus makes a contribution to the observed synergy.     

Bird and insect pollinators differ in specialization and potential pollination services along disturbance and resource gradients

Combined studies of the communities and interaction networks of bird and insect pollinators are rare, especially along environmental gradients. Here, we determined how disturbance by fire and variation in sugar resources shape pollinator communities and interactions between plants and their pollinating insects and birds. We recorded insect and bird visits to 21 Protea species across 21 study sites and for 2 years in Fynbos ecosystems in the Western Cape, South Africa. We recorded morphological traits of all pollinator species (41 insect and nine bird species). For each site, we obtained estimates of the time since the last fire (range: 2–25 calendar years) and the Protea nectar sugar amount per hectare (range: 74–62 000 g/ha). We tested how post-fire age and sugar amount influence the total interaction frequency, species richness and functional diversity of pollinator communities, as well as pollinator specialization (the effective number of plant partners) and potential pollination services (pollination service index) of insects and birds. We found little variation in the total interaction frequency, species richness and functional diversity of insect and bird pollinator communities, but insect species richness increased with post-fire age. Pollinator specialization and potential pollination services of insects and birds varied differently along the environmental gradients. Bird pollinators visited fewer Protea species at sites with high sugar amount, while there was no such trend for insects. Potential pollination services of insect pollinators to Protea species decreased with increasing post-fire age and resource amounts, whereas potential pollination services of birds remained constant along the environmental gradients. Despite little changes in pollinator communities, our analyses reveal that insect and bird pollinators differ in their specialization on Protea species and show distinct responses to disturbance and resource gradients. Our comparative study of bird and insect pollinators demonstrates that birds may be able to provide more stable pollination services than insects.