Presence of acyl-homoserine lactones in 57 members of the Vibrionaceae family.

AIMS: The aim of this study was to use a sensitive method to screen and quantify 57 Vibrionaceae strains for the production of acyl-homoserine lactones (AHLs) and map the resulting AHL profiles onto a host phylogeny. METHODS AND RESULTS: We used a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) protocol to measure AHLs in spent media after bacterial growth. First, the presence/absence of AHLs (qualitative analysis) was measured to choose internal standard for subsequent quantitative AHL measurements. We screened 57 strains from three genera (Aliivibrio, Photobacterium and Vibrio) of the same family (i.e. Vibrionaceae). Our results show that about half of the isolates produced multiple AHLs, typically at 25-5000 nmol l(-1) . CONCLUSIONS: This work shows that production of AHL quorum sensing signals is found widespread among Vibrionaceae bacteria and that closely related strains typically produce similar AHL profiles. SIGNIFICANCE AND IMPACT OF THE STUDY: The AHL detection protocol presented in this study can be applied to a broad range of bacterial samples and may contribute to a wider mapping of AHL production in bacteria, for example, in clinically relevant strains.

Androgen receptor expression in the levator ani muscle of male mice.

The spinal nucleus of the bulbocavernosus (SNB) is a sexually dimorphic group of motoneurones that innervates the bulbocavernosus (BC) and levator ani (LA), skeletal muscles that attach to the base of the penis. In many species, including mice, rats and hamsters, the LA and BC have been found to be highly responsive to androgen and, in rats, these muscles mediate several effects of androgen on the SNB system. However, characterising the SNB system in mice is important because of the availability of genetic models in this species. In the present study, we examined AR expression in skeletal muscles of C57/BlJ6 adult male mice using immunoblotting and immunocytochemistry, comparing the BC/LA to the androgen-unresponsive extensor digitorum longus (EDL). We found similar differences in AR expression for these muscles in the mouse as previously reported for rats. In mice, the BC/LA contains more AR protein than does the EDL. At the cellular level, the LA contains a higher percentage of AR positive myonuclei and fibroblasts than does the EDL. Finally, AR expression is enriched at the neuromuscular junction of mouse LA fibres. The increased expression of AR in the LA compared to the EDL in both muscle fibres and fibroblasts indicates that each cell type may critically mediate androgen action on the SNB system in mice.

Reevaluation of regression of coronary arteriosclerotic lesions in repeat-spawning steelhead trout.

At spawning, migratory salmonids have an extensive accumulation of coronary arteriosclerotic lesions. Nevertheless, when steelhead trout (Oncorhynchus mykiss) return to the ocean after spawning, an unusual phenomenon has been reported, namely, that these lesions have regressed naturally and almost completely (R.L. Van Citters and N.W. Watson, Science 1968; 159:105-107). In contrast to this earlier finding, we present data that show a high prevalence and severity of coronary lesions in 1) wild, repeat-spawning steelhead trout that were caught at high sea and 2) wild and cultured steelhead trout that had been held in sea pens for up to 1 year after maturation. Therefore, we refute the idea of natural lesion regression in steelhead trout. Coronary lesions in salmonids are characteristically lipid free despite the fact that there are high plasma levels of both total cholesterol and low density lipoproteins. This situation contrasts with the characteristic lipid deposition during lesion development in mammals. We therefore suggest that attention should be directed to explaining why coronary lesions accumulate despite very high dietary levels of omega-3 polyunsaturated fatty acids in the diets and tissues of these fish.

Effects of exercise-training on cardiac performance and muscle enzymes in rainbow trout,Oncorhynchus mykiss.

Rainbow trout,Oncorhynchus mykiss, were exercise-trained for 18 hours per day over 28 days at water velocities up to 60% of their measured Ucrit. Anin situ perfused heart preparation was used to compare maximum cardiac performance between control and trained fish. Trained fish had a larger stroke volume at a given filling pressure, as well as an 18% higher cardiac output and a 25% greater maximum power output. These observations indicate that exercise training in rainbow trout improved maximum cardiac performance. Adrenaline produced positive inotropic and chronotropic effects on the perfused heart, but exercise training did not alter these stimulatory effects. Maximal activities of citrate synthase (CS), B-hydroxyacyl CoA dehydrogenase (HOAD), glutamate dehydrogenase (GDH) and carnitine palmitoyl transferase (CPT) were measured in cardiac and skeletal muscles. CS, HOAD and GDH increased in red and white skeletal muscle as a result of training. Training also increased GDH activity in the endocardium and epicardium, and increased HOAD in the epicardium. While the training regime did not result in a statistically significant increase in Ucrit and produced a decrease in the condition factor of the fish, other training effects were clearly evident. Furthermore, significant correlations were observed between Ucrit and the maximal activities of GDH and HOAD.

Sublethal and acute toxicity of the ethylene glycol butyl ether ester formulation of triclopyr to juvenile coho salmon (Oncorhynchus kisutch).

The toxicity of Garlon4, the ethylene glycol butyl ether ester formulation of the herbicide tryclopyr, to juvenile coho salmon (Oncorhynchus kisutch) was investigated at several lethal and sublethal concentrations. Fish behavior, random activity and oxygen uptake were monitored. Coho salmon exhibited three distinct responses related to concentration and duration of exposure: (1) at concentrations greater than 0.56 mg/L fish were initially lethargic, then regressed to a highly distressed condition characterized by elevated oxygen uptake and finally death, (2) at 0.32-0.43 mg/L fish were lethargic throughout the exposure period with reduced oxygen uptake, and (3) at concentrations less than or equal to 0.10 mg/L fish were hypersensitive to stimuli, exhibiting elevated activity and oxygen uptake levels during photoperiod transitions. Whole body residue analysis showed that uptake of the ester and subsequent hydrolysis to the acid form in the fish was rapid, with significant accumulation of the acid in the tissues. This suggests that some threshold tissue concentrations were associated with the observed results. For juvenile coho salmon the 96-hr LC50 of Garlon4 was 0.84 mg/L.

IgA and IgG serum antibodies to Candida albicans in women of child-bearing age.

IgA and IgG antibodies against Candida albicans culture filtrate were determined by enzyme-linked immunosorbent assay (ELISA) in sera from 84 pregnant and 21 non-pregnant women. IgA Candida antibody levels were found not to change significantly with age, whereas IgG Candida antibody levels were significantly higher in women aged 27 to 35 years than in women less than 24 years of age. Neither IgA nor IgG Candida antibody levels were related to the number of pregnancies. In a subgroup of 45 pregnant women examined for yeasts in the oral, anal and vaginal flora IgA Candida antibody levels were significantly higher in 13 women with negative cultures than in 19 women with recovery of C. albicans on plates. Intermediate levels of IgA Candida antibodies were found in 9 women with negative plate cultures, but positive enrichment broth cultures of C. albicans. All of 15 women with IgA ELISA values less than or equal to 0.51 had yeast-positive cultures compared with 17 of 30 women with IgA ELISA values greater than 0.51. This may suggest a role of IgA antibodies in the clearance of C. albicans from mucosal surfaces in healthy individuals.