Ollulanus tricuspis in domestic cats — prevalence and methods of post-mortem diagnosis

Ollulanus tricuspus is a parasite of the stomach of domestic cats and other animals, with a worldwide distribution. It can sometimes cause severe gastritis.

Fifty-five cat stomachs were examined for O.tricuspis using three techniques. O.tricuspis was found in seven stomachs 13%) from adult cats; the number of parasites recovered from individual cats ranged from 9 to 119 (mean 54). The prevalence was higher than that previously recorded in New Zealand. Repeated dilution and sedimentation of the stomach contents and mucosal washings was found to be the most reliable detection method, being positive in all of the detected infections. Pepsin/HCI digestion of the stomach mucosa detected only 71% and punch sampling of the mucosa only 29% of these infections. This contrasts with an overseas study indicating that, in heavily infected cats, these techniques are similar in sensitivity. No macroscopic lesions were seen in the stomachs of infected cats.     

Feeding Ration,Genetics, and Reproductive Traits in Female Coho Salmon: Is Bigger Better?

We assessed the effects of different feeding regimes on reproductive traits in coho salmon, Oncorhynchus kisutch. Ration treatments subjected fish to different energy levels during oocyte proliferation (Year 1) and oocyte maturation (Year 2). Fish from 10 full‐sibling families were fed at either the recommended feeding rate or double the recommended ration during the first year. At the beginning of the second year, each ration group was split again into recommended and double ration tanks for a total of four dietary treatments. At the end of the second year, 365 females from the four treatment groups were spawned and body weight, egg weight, and egg number were measured. Overall, the fish fed the double ration during both years grew the fastest (50.1% larger than controls), had the highest egg number (46.3% larger), and had the largest eggs (9.6% larger), although similar increases were observed feeding at the double ration level during the second year alone. Ration modification produced significant changes in some reproductive traits, especially egg number, while family effects had a greater influence on relative fecundity (eggs/g female body weight) and egg weight. In fact, family effects were significant for all of the traits. Results indicate that reproductive traits can be manipulated through changes in ration and/or via genetic selection, either directly or indirectly.     

Genomics and the irreducible nature of eukaryote cells

Large-scale comparative genomics in harness with proteomics has substantiated fundamental features of eukaryote cellular evolution. The evolutionary trajectory of modern eukaryotes is distinct from that of prokaryotes. Data from many sources give no direct evidence that eukaryotes evolved by genome fusion between archaea and bacteria. Comparative genomics shows that, under certain ecological settings, sequence loss and cellular simplification are common modes of evolution. Subcellular architecture of eukaryote cells is in part a physical-chemical consequence of molecular crowding; subcellular compartmentation with specialized proteomes is required for the efficient functioning of proteins.     

Culture-independent molecular techniques for soil microbial ecology

The advent of nucleic acid-based molecular methods, in particular the polymerase chain reaction (PCR), has revolutionised the study of soil microbial ecology, previously constrained by an inability to culture the majority of cells detected by direct microscopic observation. Extraction of DNA and RNA directly from cells in soil circumvents the requirement to grow microorganisms in laboratory culture, avoiding problems associated with the differential growth rates of the estimated 1% that can be grown routinely. However, not all cells that contain DNA are capable of growth, and in some conditions such as air-dried soil, DNA can be extracted from non-viable microorganisms after 140 years of storage. To investigate the active microbial community, RNA can also be isolated directly from soil. Analysis of ribosomal RNA (rRNA) indicates the dominant active population in any particular set of conditions and the large, constantly increasing electronic database of gene sequences for the small subunit of rRNA (16S for prokaryotes, 18S for eukaryotes) provides identification of many soil bacteria, archaea and fungi with varying degrees of certainty to the genus, species or sub-species level. More precise information on which functional genes are active can be obtained from messenger RNA (mRNA). Newer methods including high-throughput (massively parallel) sequencing and microarrays offer further advances. We describe a range of molecular techniques used to investigate soil microbial communities, discuss how they relate to other methods for investigating bacterial and fungal activity, and explore their drawbacks and limitations.     

Sensitive PCR analysis of animal tissue samples for fragments of endogenous and transgenic plant DNA

An optimized DNA extraction protocol for animal tissues coupled with sensitive PCR methods was used to determine whether trace levels of feed-derived DNA fragments, plant and/or transgenic, are detectable in animal tissue samples including dairy milk and samples of muscle (meat) from chickens, swine, and beef steers. Assays were developed to detect DNA fragments of both the high copy number chloroplast-encoded maize rubisco gene (rbcL) and single copy nuclear-encoded transgenic elements (p35S and a MON 810-specific gene fragment). The specificities of the two rbcL PCR assays and two transgenic DNA PCR assays were established by testing against a range of conventional plant species and genetically modified maize crops. The sensitivities of the two rbcL PCR assays (resulting in 173 and 500 bp amplicons) were similar, detecting as little as 0.08 and 0.02 genomic equivalents, respectively. The sensitivities of the p35S and MON 810 PCR assays were approximately 5 and 10 genomic equivalents for 123 bp and 149 bp amplicons, respectively, which were considerably less than the sensitivity of the rbcL assays in terms of plant cell equivalents, but approximately similar when the higher numbers of copies of the chloroplast genome per cell are taken into account. The 173 bp rbcL assay detected the target plant chloroplast DNA fragment in 5%, 15%, and 53% of the muscle samples from beef steers, broiler chickens, and swine, respectively, and in 86% of the milk samples from dairy cows. Reanalysis of new aliquots of 31 of the pork samples that were positive in the 173 bp rbcL PCR showed that 58% of these samples were reproducibly positive in this same PCR assay. The 500 bp rbcL assay detected DNA fragments in 43% of the swine muscle samples and 79% of the milk samples. By comparison, no statistically significant detections of transgenic DNA fragments by the p35S PCR assay occurred with any of these animal tissue samples.     

Atmospheric hydrogen sulfide levels at the sulphur bay wildlife area,Lake Rotorua,New Zealand

At the Sulphur Bay Wildlife area on Lake Rotorua, shore and water birds are exposed to natural H₂S at concentrations of 125 to 3900 ppbV from continuous shore and lake sources. Nevertheless, 62 bird species, 45 native, have been recorded there. Regular residents include Red-Billed Gull, Dabchick Mallard Duck, Black Swan and Caspian Tern. Some, the Red Billed Gull and Little Black Shag, have initiated colonization within the past half-century. We suggest that exposure to H₂S at the levels reported here may be less of a biohazard than previously supposed.     

A contribution to the environmental biology of mercury accumulation in plants

Samples of six common plant species collected in the old mining areas near Prince George, British Columbia (Canada) and Mount Amiata, Tuscany (Italy) show remarkable similarities in the variation of plant/soil Hg concentration ratio with soil Hg content irrespective of species or other biological differences. In contrast, plants sampled in the geothermally active areas of New Zealand, Hawaii and around Mount St. Helens exhibit more individuality in the concentration ratio to soil Hg relationship, but the relationships are distinctly different from the mine site specimens. This distinction is particularly evident when the same species of Equisetum and Plantago taken from these two different areas are compared. These and other data support the hypothesis that specific local environmental factors strongly influence the accumulation of Hg in plants even when the immediate soil concentrations are the same. Our findings show that some plants contain concentrations of total Hg as high as 5500 to 14000 μg kg^?1 (dw).