A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths

Molecular systematists need increased access to nuclear genes. Highly conserved, low copy number protein-encoding nuclear genes have attractive features for phylogenetic inference but have heretofore been applied mostly to very ancient divergences. By virtue of their synonymous substitutions, such genes should contain a wealth of information about lower-level taxonomic relationships as well, with the advantage that amino acid conservatism makes both alignment and primer definition straightforward. We tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene in the noctuid moth subfamily Heliothinae, which has probably diversified since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing heliothine groupings strongly supported by previous morphological and allozyme studies. The single most parsimonious gene tree and the neighbor-joining tree for all nucleotides show almost complete concordance with the morphological tree. Homoplasy and pairwise divergence levels are low, transition/transversion ratios are high, and phylogenetic information is spread evenly across gene regions. The EF-1 alpha gene and presumably other highly conserved genes hold much promise for phylogenetics of Tertiary age eukaryote groups.      

Chick embryo fibroblasts produce two forms of hyaluronidase

Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu.     

The vulnerability of animal and human health to parasites under global change

The term 'global change' is used to encompass all of the significant drivers of environmental change as experienced by hosts, parasites and parasite managers. The term includes changes in climate and climate variability, atmospheric composition, land use and land cover including deforestation and urbanisation, bio-geochemistry, globalisation of trade and transport, the spread of alien species, human health and technology. A subset of land use issues relates to the management of protective technologies in relation to residues in food and the environment and the emergence of resistance. Another is the question of changing biodiversity of both parasites and their associated natural enemies, and the effects on the host--parasite relationship and on parasite management. A framework for studying impacts of global change is proposed and illustrated with field data, and CLIMEX and simulation modelling of the cattle tick Boophilus microplus in Australia. Parasitology suffers from the perception that the key impacts of global change will be driven by changes at lower trophic levels, with parasitic interactions being treated as secondary effects. This is incorrect because the environment mediates host-parasite interactions as much as it affects parasites directly. Parasitologists need to strive for holistic solutions to the management of animal and human health, within a wider context of overall management of those systems, if they are to make a meaningful contribution to global efforts aimed at coping with global change.     

Campylobacter lari: genotype and antibiotic resistance of isolates from cattle, wildlife and water in an area of mixed dairy farmland in the United Kingdom

Campylobacter lari is a rare human pathogen most commonly associated with birds and shellfish. Little information has been published regarding its prevalence in other environments, or on its potential role as a reservoir of antibiotic resistance. In this study, we characterized 109 C. lari isolated from a range of hosts using pulsed-field gel electrophoresis of macro-restricted chromosomal DNA, and by determining their susceptibility to a panel of four antibiotics. Pulsed-field gel electrophoresis analysis showed C. lari to be genetically diverse, particularly in isolates from wild birds and environmental water. The most common composite macro-restriction profile (cMRP) was found in multiple hosts (cattle, badgers, wild birds and rabbits), and seven other cMRPs were recovered from more than one host. All isolates were resistant to nalidixic acid and ciprofloxacin. Resistance to erythromycin and ampicillin was uncommon, but was observed in isolates from wild birds, cattle, wild mammals and water samples. The presence of the same cMRP in multiple hosts provides further evidence of transmission between livestock, wildlife and the environment, or for a common source of infection.     

Biological staining: mechanisms and theory

New staining techniques continue to be introduced, and older ones continue to be used and improved. Several factors control specificity, selectivity and visibility of the end product in any procedure using dyes, fluorochromes, inorganic reagents or histochemical reactions applied to sections or similar preparations. Local concentration of the tissue target often determines the intensity of the observed color, as does the fine structure within the object being stained, which may facilitate or impede diffusion of dyes and other reagents. Several contributions to affinity control the specificity of staining. These include electrical forces, which result in accumulation of dye ions in regions of oppositely charged tissue polyions. Weaker short-range attractions (hydrogen bonding, van der Waals forces or hydrophobic bonding, depending on the solvent) hold dyes ions and histochemical end products in contact with their macromolecular substrates. Nonionic forces can also increase visibility of stained sites by causing aggregation of dye molecules. Covalent bonds between dye and tissue result in the strongest binding, such as in methods using Schiff's reagent and possibly also some mordant dyes. The rate at which a reagent gains access to or is removed from targets in a section or other specimen affect what is stained, especially when more then one dye is used, together or sequentially. Rate-controlled staining is greatly influenced by the presence and type of embedding medium, such as a resin, that infiltrates the tissue. The rates of chemical reactions are major determinants of outcome in many histochemical techniques. Selective staining of different organelles within living cells is accomplished mainly with fluorochromes and is controlled by mechanisms different from those that apply to fixed tissues. Quantitative structure-activity relations (QSAR) of such reagents can be derived from such molecular properties as hydrophilic-hydrophobic balance, extent of conjugated bond systems, acid-base properties and ionic charge. The QSAR correlates with staining of endoplasmic reticulum, lysosomes, mitochondria, DNA, or the plasma membranes of living cells.     

MAGI: Methylation analysis using genome information

By incorporating annotation information into the analysis of next-generation sequencing DNA methylation data, we provide an improvement in performance over current testing procedures. Methylation analysis using genome information (MAGI) is applicable for both unreplicated and replicated data, and provides an effective analysis for studies with low sequencing depth. When compared with current tests, the annotation-informed tests provide an increase in statistical power and offer a significance-based interpretation of differential methylation.     

Resistance in cattle to Haemaphysalis (Kaiseriana) longicornis

Samples of each instar of the 3-host tick, Haemaphysalis (Kaiseriana) longicornis were collected from grazing Bos taurus cattle to investigate their survival on hosts with previous exposure to the tick and on previously unexposed ‘naive’ hosts. The ticks were allocated to categories based on their size to observe at what stage of development mortality occurred. Analysis of the age structure of the ticks showed that small but variable proportions of larvae, nymphs and females matured on previously exposed hosts and larger proportions on the naive hosts. This suggests that cattle acquire and express different levels of resistance against each instar of the tick. The technique used has potential for estimating levels of resistance of hosts to 3-host ticks under field conditions.     

Size of the first spring generation of Helicoverpa punctigera (Wallengren) (Lepidoptera: Noctuidae) and winter rain in central Australia

Serious infestations of Helicoverpa punctigera are experienced yearly in the eastern cropping regions of Australia. Regression analysis was used to determine whether the size of the first generation in spring (G₁), which is comprised mostly of immigrants from inland Australia, was related to monthly rainfall in inland winter breeding areas. Data from two long series of light-trap catches at Narrabri in New South Wales (NSW) and Turretfield in South Australia (SA) were used in the analyses. The size of G₁ at Narrabri in each year was significantly regressed on the amount of rainfall in western Queensland and NSW in May and June. The size of G₁ at Turretfield each year was significantly regressed on the amount of rain in May, June and July in western Queensland and NSW and also in the desert of central Western Australia. Low r ² values of the regressions suggest that rainfall data for more sites, as well as biological and other physical factors, such as temperature, evaporation, and prevailing wind systems, may need to be included to improve forecasts of the potential magnitude of the infestations in coastal cropping regions.