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Biomedical subjects

S Trudeau

Publications and source records attributed to S Trudeau.

11 recordsLinked to original sources
PubMed2000

Organochlorines and possible biochemical effects in glaucous gulls (Larus hyperboreus) from Bjørnøya, the Barents Sea.

To study possible biochemical effects of organochlorine contaminants (OCs) in glaucous gulls (Larus hyperboreus), 40 adult individuals were collected from colonies on Bjornoya in the Barents Sea. OCs (four pesticides and nine PCB congeners), microsomal 7-ethoxyresorufin O-deethylase (EROD) activity, microsomal testosterone hydroxylation, highly carboxylated porphyrins (HCPs), retinol, and retinyl palmitate were quantified in liver samples. The hepatic vitamin A stores in glaucous gulls were larger than in herring gulls (Larus argentatus) from other studies conducted in contaminated locations in North America. No significant relationships were found between liver retinoid concentrations and OC levels. The hepatic EROD activity was low compared to other studies on fish-eating birds and only marginally associated with PCB levels. Microsomal testosterone hydroxylase activity was only observed at the 6beta-position and could not be related to OC levels. The low P450-associated enzyme activities in the glaucous gull suggests that they have a low capacity for metabolizing OCs, which may contribute to the high accumulation of OCs in this species. HCPs were only elevated (138 pmol g(-1)) in the sample with highest OC levels, whereas the remaining samples contained low levels of HCPs (<30 pmol g(-1)). The weak association between EROD activity and PCB levels and the low level of HCPs suggest that these biochemical parameters were unaffected by OCs in most of the sampled gulls. Thus, the glaucous gull seems not to be particularly sensitive toward Ah-receptor mediated effects.

Animals↗
PubMed1995

Experimental vitamin A deficiency in mallards (Anas platyrhynchos): lesions and tissue vitamin A levels.

Captive mallards (Anas platyrhynchos), fed an all-grain diet for up to 5 months during the winters of 1991 to 1992 and 1992 to 1993, developed lesions of squamous metaplasia; some had no detectable hepatic vitamin A. Vitamin A deficiency in mallards was defined as hepatic levels of retinyl palmitate < 2 micrograms/g liver. Lesions were found only in ducks with low levels of hepatic vitamin A, but not all ducks with these low levels of hepatic vitamin A had histological lesions. The prevalence of lesions in the esophagus was greatest cranially and caudally and less common in the central region. Palatine salivary glands rarely were affected. Mallards with liver stores > 600 micrograms of hepatic retinyl palmitate per g liver, fed a diet deficient in vitamin A were unlikely to become deficient over a 5 month period. Birds fed an all-grain diet had significantly lower vitamin A concentrations in their liver compared to those fed an all-grain diet with vitamin A added. Liver weight, when corrected for body size, did not affect vitamin A concentration. Serum retinol levels were conserved over a large range of hepatic vitamin A levels but levels below 300 micrograms retinol/l were useful in detecting vitamin A deficiency in captive mallards. Based on the findings, the presence of lesions provides a conservative measure of vitamin A status in ducks and tissue levels should be measured in instances when mallards have questionable vitamin A status.

Animals↗
PubMed1995

Vitamin A status of wild mallards (Anas platyrhynchos) wintering in Saskatchewan.

Vitamin A status of wild male mallards (Anas platyrhynchos) overwintering in Saskatchewan, Canada was determined. Vitamin A levels < 0.2 micrograms hepatic retinyl palmitate/g liver, occurred in 6% and 25% of male mallards sampled in 1991 to 1992 and 1992 to 1993, respectively. There was no temporal trend in vitamin A levels over either winter. Squamous metaplastic lesions, commonly associated with vitamin A deficiency in domestic animals, were not observed in any bird; hence, they were not a good indicator of vitamin A status in wild mallards. Serum retinol was not a good indicator of vitamin A status in wild mallards. Many mallards in good body condition had low vitamin A levels; thus, we propose that good body condition and ample fat stores are not indicative of overall health of the bird.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Towards molecular understanding of species differences in dioxin sensitivity: initial characterization of Ah receptor cDNAs in birds and an amphibian.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related planar halogenated aromatic hydrocarbons (PHAHs) are highly toxic to most vertebrate animals, but there are dramatic species differences in sensitivity, both within and among vertebrate classes. For example, studies in cultured avian hepatocytes have revealed differential sensitivity of birds to PHAHs [Kennedy et al. (1996). Toxicol. Appl. Pharmacol., 141, 214-230]. Differences in the characteristics or expression of the aryl hydrocarbon receptor (AHR) could contribute to these species differences in PHAH responsiveness. To investigate the molecular mechanism of differential PHAH sensitivity, we have begun to characterize the AHR in white leghorn chicken (Gallus gallus), Pekin duck (Anas platyrhynchos), and common tern (Sterna hirundo), as well as an amphibian, mudpuppy (Necturus maculosus). Partial AHR cDNAs encompassing the helix-loop-helix and PAS domains were cloned and sequenced. Comparison of amino acid sequences in this region indicated a high degree of sequence conservation among the bird species (97% amino acid identity). The percent identity between bird sequences and either mouse or mudpuppy was lower (79%); the mudpuppy AHR was 74% identical to the mouse AHR. Phylogenetic analysis of these and other AHR amino acid sequences showed that the bird and mudpuppy AHRs were more closely related to mammalian and fish AHR1 forms than to fish AHR2. Future studies include the in vitro expression and functional characterization of AHRs from these and other non-mammalian vertebrates.

Amino Acid Sequence↗