Identification of auto-antigens in skin scrapings from scabies-infected pigs

Sarcoptes scabiei continues to cause major health and economic problems in a large range of animals and humans. Although the inflammatory response to the mite and its antigens is known to cause the main pathology, little work has been carried out on this response at the site of infection. This report presents an initial analysis of the proteins found in skin scrapings and their antigenic responsiveness in pigs. Skin scrapings and mite extracts were isolated from chronically infected sows while infected and uninfected sera were isolated from pigs with confirmed infections or mange-free pigs, respectively. Electrophoresis and sequencing confirmed the main components of both the skin and mite extracts to be serum proteins. Immunoblotting then suggested that transferrin was the major antigen recognised by pooled infected sera in the skin and the mite extracts. Immunoassays confirmed that a majority of infected pigs produced antibodies to transferrin while mange-free pigs did not. A pool of IgG from infected dogs was then used to isolate another antigen from pig skin scrapings which was shown to be haptoglobin. This was also found to induce high titres of antibody in infected pigs as compared with mange-free pigs. The use of albumin as a control antigen showed no reactivity in either group of sera. The finding of two iron-binding molecules as strong auto-antigens in pig scabies has implications for the importance of iron during this infection and may help to explain the persistence and magnitude of the host inflammatory response.     

Motile sperm organelle morphology examination (MSOME): intervariation study of normal sperm and sperm with large nuclear vacuoles

Background  

Although the motile sperm organelle morphology examination (MSOME) was developed only as a selection criterion, its application as a method for classifying sperm morphology may represent an improvement in evaluation of semen quality, with potential clinical repercussions. The present study aimed to evaluate individual variations in the motile sperm organelle morphology examination (MSOME) analysis after a time interval.     

Characterization of 13 newly isolated strains of anaerobic, cellulolytic, thermophilic bacteria

Characteristics of 13 newly isolated thermophilic, anaerobic, and cellulolytic strains were compared with previously described strains of Clostridium thermocellum: ATCC 27405 and JW20 (ATCC 31549). Colony morphology, antibiotic sensitivity, fermentation end-products, and cellulose degradation were documented. All 13 strains were sensitive to erythromycin (5 μg/ml) and chloramphenicol (25 μg/ml), and all strains but one were sensitive to kanamycin (20 μg/ml). Polymerase chain reaction (PCR) amplification using primers based on gene sequences from C. thermocellum ATCC 27405 was successful for all 13 strains in the case of the hydrogenase gene and 11 strains in the case of phosphotransacetylase/acetate kinase genes. Ten strains amplified a product of the expected size with primers developed to be specific for C. thermocellum 16SrRNA primers. Two of the 13 strains did not amplify any product with the PCR primers designed for the phosphotransacetylase/acetate kinase and 16SrRNA primers. A MboI-like GATC- recognizing restriction activity was present in all of the five strains examined. The results of this study have several positive implications with respect to future development of a transformation system for cellulolytic thermophiles. Journal of Industrial Microbiology & Biotechnology (2001) 27, 275–280. Received 12 September 2000/ Accepted in revised form 20 November 2000     

Regulation of life-long neurogenesis in the decapod crustacean brain

This article provides an overview of our understanding of life-long neurogenesis in the decapod crustacean brain, where the proliferation of sensory and interneurons is controlled by many of the same factors as is neurogenesis in the mammalian brain. The relative simplicity, spatial organization and accessibility of the crustacean brain provide opportunities to examine specific neuronal pathways that regulate neurogenesis and the sequence of gene expression that leads to neuronal differentiation.     

Rational engineering of the TOL meta-cleavage pathway

The meta-cleavage pathway of Pseudomonas putida mt-2 was simulated using a biochemical systems simulation developed by Regan (1996). A non-competitive inhibition term for catechol-2,3-dioxygenase (C23O) by 2-OH-pent-2,4-dienoate (Ki = 150 μM) was incorporated into the model. The simulation predicted steady state accumulation levels in the μM range for metabolites pre-meta-cleavage, and in the mM range for metabolites post-meta-cleavage. The logarithmic gains L[V-i, Xj] and L[X-i, Xj] clearly indicated that the pathway was most sensitive to the concentration of the starting substrate, benzoate, and the first enzyme of the pathway, toluate-1, 2-dioxygenase (TO). The simulation was validated experimentally; it was found that the amplification of TO increased the steady state flux from 0.024 to 0.091 (mmol/g cell dwt)/h. This resulted in an increased accumulation of a number of the pathway metabolites (intra- and extracellularly), especially cis-diol, 4-OH-2-oxovalerate, and 4-oxalocrotonate. Metabolic control analysis indicated that C23O was, in fact, the major controling enzymic step of the pathway with a scaled control coefficient of 0.83. The amplification of TO resulted in a shift of some of the control away from C23O. Catechol-2,3-dioxygenase, however, remained as the major controling element of the pathway. Copyright 1998 John Wiley & Sons, Inc.     

Higher-level snake phylogeny inferred from mitochondrial DNA sequences of 12S rRNA and 16S rRNA genes

Portions of two mitochondrial genes (12S and 16S ribosomal RNA) were sequenced to determine the phylogenetic relationships among the major clades of snakes. Thirty-six species, representing nearly all extant families, were examined and compared with sequences of a tuatara and three families of lizards. Snakes were found to constitute a monophyletic group (confidence probability [CP] = 96%), with the scolecophidians (blind snakes) as the most basal lineages (CP = 99%). This finding supports the hypothesis that snakes underwent a subterranean period early in their evolution. Caenophidians (advanced snakes), excluding Acrochordus, were found to be monophyletic (CP = 99%). Among the caenophidians, viperids were monophyletic (CP = 98%) and formed the sister group to the elapids plus colubrids (CP = 94%). Within the viperids, two monophyletic groups were identified: true vipers (CP = 98%) and pit vipers plus Azemiops (CP = 99%). The elapids plus Atractaspis formed a monophyletic clade (CP = 99%). Within the paraphyletic Colubridae, the largely Holarctic Colubrinae was found to be a monophyletic assemblage (CP = 98%), and the Xenodontinae was found to be polyphyletic (CP = 91%). Monophyly of the henophidians (primitive snakes) was neither supported nor rejected because of the weak resolution of relationships among those taxa, except for the clustering of Calabaria with a uropeltid, Rhinophis (CP = 94%).      

Dense-core vesicles and non-synaptic exocytosis in the central body of the crayfish brain

Summary The central body in the median protocerebrum of the brain of the crayfish Cherax destructor is a distinctive area of dense neuropile, the nerve fibres of which contain three main types of vesicles: electronlucent vesicles (diameter 35 nm), dense-core vesicles (diameter 64 nm), and large structured dense-core vesicles (diameter 98 nm, maximum 170 nm). Different vesicle types were found together in the same neurons. Electronlucent vesicles were seen at presynaptic sites and rarely observed in the state of exocytosis. Exocytosis of densecore and structured dense-core vesicles was a regular feature on non-synaptic release sites either close to, or at some distance from pre- and subsynaptic sites. Non-synaptic exocytotic sites are more often observed than chemical synapses. Different forms of exocytosis seen at non-synaptic sites included the release of single densecore vesicles, packets of dense-core vesicles, and rows of dense-core vesicles lined up along cell membranes and around fibre invaginations. Swelling and the enhanced electron density of extracellular non-synaptic spaces may mark the positions of prior exocytotic events. In vitro treatment of the brain with tannic acid buffer solution followed by conventional double fixation resulted in the augmentation of non-synaptic exocytosis. Electron microscopy of proctolin- and serotonin-immunoreactive nerve fibres shows them to contain dense-core and electron-lucent vesicles and to be surrounded by many unlabelled profiles similarly laden with dense-core vesicles and electron-lucent vesicles, indicating the presence of other, not yet identified, neuroactive compounds.     

The organisation of the lamina ganglionaris of the crabs Scylla serrata and Leptograpsus variegatus

Summary The gross structure and neuronal elements of the first optic ganglion of two crabs, Scylla serrata and Leptograpsus variegatus, are described on the basis of Golgi (selective silver) and reduced silver preparations. Of the eight retinula cells of each ommatidium, seven end within the lamina, while the eighth cell sends a long fibre to the external medulla. Five types of monopolar neurons are described, three types of large tangential fibres, and one fibre which may be centrifugal. The marked stratification of the lamina is produced by several features. The main synaptic region, the plexiform layer, is divided by a band of tangential fibres; the short retinula fibres end at two levels in the plexiform layer; and two types of monopolar cells have arborisations confined to the distal or proximal parts of the plexiform layer. The information presently available concerning the retina-lamina projection in Crustacea is examined. Some of the implications of retina and lamina structure are discussed in conjunction with what is known about their electrophysiology.     

Molecular dynamics of synthetic leucine-serine ion channels in a phospholipid membrane

Molecular dynamics calculations were carried out on models of two synthetic leucine-serine ion channels: a tetrameric bundle with sequence (LSLLLSL)(3)NH(2) and a hexameric bundle with sequence (LSSLLSL)(3)NH(2). Each protein bundle is inserted in a palmitoyloleoylphosphatidylcholine bilayer membrane and solvated by simple point charge water molecules inside the pore and at both mouths. Both systems appear to be stable in the absence of an electric field during the 4 ns of molecular dynamics simulation. The water motion in the narrow pore of the four-helix bundle is highly restricted and may provide suitable conditions for proton transfer via a water wire mechanism. In the wider hexameric pore, the water diffuses much more slowly than in bulk but is still mobile. This, along with the dimensions of the pore, supports the observation that this peptide is selective for monovalent cations. Reasonable agreement of predicted conductances with experimentally determined values lends support to the validity of the simulations.