Role of diet and experience in the development of feeding behaviour in largemouth bass, Micropterus salmoides

Two groups of largemouth bass, Micropterus salmoides , were reared in the laboratory. One group was reared on an artificial, passive diet (frozen brine shrimp) whereas the second was reared on a natural, active diet (cultured zooplankton). Observations on the development of feeding behaviour indicated that the motor patterns and duration (number of weeks in the behavioural repertoire) of the feeding acts did not differ between fry reared on the two diets. While feeding on their respective diets, natural-diet fry performed significantly more orientations and bites, the two major early feeding acts, than did the artificial-diet fry. When tested with live fish prey, fish reared on the natural diet performed fewer orientations and strikes and captured more prey per fry than did the artificial-diet fry. Natural-diet fry had a significantly better net efficiency (captures minus strikes minus orientations) than did artificial-diet fry. Diet, experience, and length (T.L.) of fry affected their predator efficiency significantly. We argue that providing hatchery-reared bass fry with an opportunity to prey on live forage fish once or twice before their release would enhance their survival and eventual recruitment into natural populations.     

Phylogenetic relationships among the black fly species (Diptera: Simuliidae) of Thailand based on multiple gene sequences

Simulium is a very speciose genus of the black fly family Simuliidae that includes many important pests of humans and animals. Cytotaxonomic and morphological studies have made substantial progress in Simulium systematics. 16S rRNA and ITS-1 DNA sequence studies have assisted this progress. Intensive multi-gene molecular systematic investigations will, however, be required for a comprehensive understanding of the genus’ taxonomy and evolution. Our research was conducted to investigate the relationships of Thai Simulium at the subgeneric, species group and species levels. We also examined the possibility of using mitochondrial DNA sequences to facilitate Simulium species identification. Data were collected from three mitochondrial genes (COI, ND4 and 16S rRNA) and two segments of the nuclear 28S ribosomal RNA (the D1 to D2 and the D4 expansion regions). The subgenera Simulium and Gomphostilbia were monophyletic in most analyses. Nevermannia included Montisimulium but was otherwise monophyletic in multigene analyses. In most analyses, Simulium and Nevermannia were more closely related to each other than to Gomphostilbia which was usually basal. Species groups were generally monophyletic. Within Gomphostilbia, however, the batoense species group was always paraphyletic to the other two species groups found in Thailand. Three species groups in Simulium were not monophyletic. The tendency to gill filament number reduction for some species groups in the subgenus Simulium was associated with a derived position in multigene analyses. Most species were monophyletic with two exceptions that probably represent species complexes and will present difficulties for rapid mitochondrial DNA identification.     

Platelet aggregation and ATP secretion in whole blood of normal cats and cats homozygous and heterozygous for Chediak-Higashi syndrome

A rapid and simple technique using the Whole Blood Lumi-Aggregometer was used to study storage pool disease in Chediak-Higashi homozygote and heterozygote cats. Feline Chedlak-Higashi platelets aggregated after the addition of both ADP and collagen. During platelet aggregation, ATP secretion was assayed; the whole blood aggregometer is effective in detecting decreased levels of secretable ATP in homozygote cats. No storage pool deficiency was found in heterozygote cats. However, upon analysis of impedance tracings, a decreased platelet aggregation response was seen in both homozygote and heterozygote cats. These results suggest that prolonged bleeding times in Chediak-Higashi cats may involve a mechanism in addition to a dense granule deficiency.     

Human Risks from the Combustion of SRM-Derived Tallow in Ireland

The identification of meat and bone meal (MBM) as a significant factor in the spread of bovine spongiform encephalopathy (BSE) has resulted in the introduction of restrictions on the use and movement of MBM and tallow. This has led to a requirement for alternative uses for these products. This paper reports on a risk assessment performed on the use of tallow as a fuel oil extender in diesel engines. With up to 4000 tonnes of tallow being produced each year in Ireland, combustion with energy recovery represents a viable, cost-efficient utilization route. A stochastic (Latin Hypercube sampling) simulation model was developed to assess the infectiv-ity risk to humans associated with potential airborne exposure to the combustion products when using tallow as a combustion fuel in diesel engines. The model simulates the potential infectivity pathways that tallow follows, including its production from animals with potentially subclinical BSE and processing the tallow with segregation and heat treatments. The model uses probability distributions for the most important input parameters. The assessment takes into account a number of epidemiological parameters that include tissue infectivity, species barrier, disease incidence, and heat inactivation. Two scenarios, reflecting the infectivity risk in different animal tissues defined by the European Commissions Scientific Steering Committee (SSC), were performed. It is seen from the model results that the risk of a human contracting variant Creutzfeldt-Jakob Disease (vCJD) from potential airborne exposure to BSE, resulting from the combustion of tallow, is extremely small even when model uncertainty is taken into account (mean individual risk values ranging from 10^-11.43 to 10^-7.23 per year/person). The risks are a number of orders of magnitude less than the sporadic annual incidence level of Creutzfeldt-Jakob Disease 9CJD) in Europe (approximately 10^-6)