Matriarchal genetic population structure of North American beluga whales Delphinapterus leucas (Cetacea: Monodontidae).

The North American beluga whale Delphinapterus leucas population has been divided into a number of putative geographical stocks based upon migration routes and areas of summer concentration. Nucleotide sequences of the mitochondrial DNA (mtDNA) control region were used to assess whether these geographical stocks are genetically distinct. Beluga whale samples from 25 sites were collected primarily from aboriginal subsistence hunts across North America from 1984 to 1994. Thirty-nine mtDNA haplotypes were identified in 628 beluga samples. No differences were found in the distribution of haplotypes between male and female beluga whales at any sampling site. These haplotypes segregated into two distinct assemblages in both a haplotype network and a neighbour-joining tree. The haplotype assemblages and a geographically disjunct distribution that suggests postglacial recolonization of the North American Arctic from two different refugia. An analysis of molecular variance based on haplotype relationships and frequency indicated genetic heterogeneity among beluga whale summering groups (P < or = 0.001). Sequence divergence estimates between sampling sites also indicated geographical differentiation, particularly between samples taken at east Hudson Bay or St Lawrence River and the western or central Arctic. The results of this study show a high degree of philopatry to specific summering areas by this highly mobile animal.

Sheep dip chemicals and water pollution.

The Tweed River Purification Board's objective of reducing the numbers and significance of water pollution incidents by a proactive approach based on persuasion and education is described. This has consisted of prioritising potential pollutant sources which have then been investigated in detail followed by discussion and agreement with dischargers as to remedial measures. The paper describes in detail the Board's investigation of pollution from the organophosphate (OP) sheep dips, Diazinon and Propetamphos, and their effects on surface waters throughout its area. Examination of historical incidents and a preliminary survey of sheep farms in the Ettrick Water catchment in 1989 confirmed the potential for serious pollution. Comparison of OP concentrations in the Ettrick with strategic sites throughout the catchment confirmed the widespread nature of the problem and led to visits to every sheep farmer in the Board's area in 1990 and 1991, when 795 dippers were investigated. The study involved risk assessments of the location of dippers and the spent dip disposal practice which confirmed that poor siting, inadequate disposal and particularly poor management of the dipping operation were responsible for the pollution problems observed. Practical advice on the management of dipping and disposal of spent dip was given individually to farmers. The success of the project in reducing pollution is reflected in a significant and sustained reduction in OP concentrations in environmental samples. The future of ectoparasitic treatments for sheep, the potential for antidotes to spent sheep dip and legal obligations relating to its safe disposal is also considered.

Microsatellites from the beluga whale Delphinapterus leucas.

Fifteen microsatellites were isolated from a beluga whale Delphinapterus leucas, genomic library. The microsatellites were amplified in 100 beluga obtained from two widely separated locations. An average of 8.6 alleles per locus were detected and the average heterozygosity was 0.65 with a range of 0.27-0.86. All microsatellites were polymorphic and 13 of the genotype distributions observed were in Hardy-Weinberg equilibrium. It was possible with these microsatellites to assign correctly individual whales to their stock-of-origin 98% of the time. Microsatellites were amplified in 15 other cetaceans with these beluga-derived primers.

Evaluation of aflatoxin B1 mutagenesis: addition of glutathione and glutathione-S-transferase to the Salmonella mutagenicity assay.

The effects of glutathione (GSH) and the combination of GSH and glutathione-S-transferase (GST) on aflatoxin B1 (AFB1) mutagenesis in the Salmonella mutagenicity assay using Salmonella typhimurium strains TA98 and TA100 were tested. Ten concentrations of AFB1 (0-1.0 micrograms/plate) were added to a liver microsomal homogenate (S9 mix) or to S9 mix containing GSH or S9 mix containing the combination of GSH + GST. One-third of the samples were plated directly. Two-thirds were incubated for 30 min at 37 degrees C prior to plating, and of those, half included bacteria. All samples were plated according to Ames et al [1975]. The results show that the addition of GSH and GSH + GST affected AFB1 mutagenesis by forming the AFB1-GSH conjugate and decreasing the availability of AFB1-8,9-epoxide. The effect of GST on GSH activity varied with the strain because of the different amounts of S9 mix used. The formation of the AFB1-GSH conjugate was verified by using reverse-phase high-performance liquid chromatography for quantitation of AFB1 and detection of AFB1-GSH.

Chlorotrifluoroethylene nephrotoxicity in rats: a subacute study.

Male Fischer-344 rats were exposed via inhalation to a sublethal concentration (395 ppm +/- 33 ppm; 1882 mg/m3) of the nephrotoxin chlorotrifluoroethylene (CTFE) for 4 h per day for 5 consecutive days. Within 1 day after the first exposure, rats exhibited diuresis, increased water intake, decreased urine osmolality, increased urinary lactic dehydrogenase activity and increased plasma creatinine and urea nitrogen. When animals were exposed repeatedly, values for these parameters declined or returned to control levels during the exposure sequence in a manner comparable to rats receiving the single exposure. By the third day post exposure, coagulative necrosis involving primarily the pars recta, but extending to the pars convoluta, of the proximal tubule was present. Regeneration was apparent by the third day of exposure, and additional necrosis was minimal despite further exposures. Daily levels of urinary inorganic fluoride, an index of CTFE metabolism, were increased to 3-6 mu moles/24 h/rat during the exposure sequence which coincided with a brief elevation in serum fluoride at the end of each exposure. Adaptation to CTFE is evident either through changes in the metabolism or disposition of CTFE or from a refractive property of the regenerating tissue to CTFE.

Toxicology of the fluoroalkenes: review and research needs.

In this review of the published literature on the toxicology of fluoroalkenes several features emerge and research needs are evident. The fluoroalkenes vary widely in acute inhalation toxicity. Those, such as perfluoroisobutylene, PFIB, the most highly toxic member, attacks the pulmonary epithelium of rats eventuating in edema and death after a delay of about one day. Other fluoroalkenes, such as hexafluoropropylene (HFP) or chlorotrifluoroethylene (CTFE), also cause pulmonary injury but at lower concentrations produce concentration dependent changes in the renal concentrating mechanism of the rat. Changes in the CNS of rats and rabbits have also been reported for CTFE. CTFE, in repeated exposures, has produced blood pressure changes in dogs, CNS effects and changes in the erythropoietic system. This variety of responses indicates the need for investigation. Chronic effects have not been sufficiently studied for PFIB and HFP. Thus pointing up the desirability for study. Mechanisms of action research for fluoroalkenes is an important area of need. While several ideas have been suggested, there are no data to support them. The nucleophilic sensitivity of the fluoroalkenes and the potential carcinogenic effects stemming therefrom suggests a need field for investigation. We also can readily perceive the needs for the evaluation of effects on reproduction (including mutagenesis and teratogenesis), metabolism pulmonary functions, cellular function and structure. Epidemiologic studies on occupationally exposed populations are desirable in order to adequately define human health hazard from these fluorocarbons.

Chronic toxicity of a synthetic tri-aryl phosphate oil to fish.

Rainbow trout (Salmo gairdneri) were exposed to IMOL S-140, a synthetic high-temperature lubricating oil composed of tri-aryl phosphates and, although no sign of acute toxicity was evident, the fish slowly developed symptoms of chronic posioning. Thus, floating food pellets were refused, the activities of glutamic oxalacetic transaminase and lactate dehydrogenase in serum were greatly elevated, and internal fatty tissues became discoloured. Neither serum nor brain cholinesterase activities were inhibited.