The Detection of Hamster Connexins: A Comparison of Expression Profiles with Wild-Type Mouse and the Cancer-Prone Min Mouse

The open reading frames of 17 connexins from Syrian hamster (using tissues) and 16 connexins from the Chinese hamster cell line V79, were fully (Cx30, Cx31, Cx37, Cx43 and Cx45) or partially sequenced. We have also detected, and partially sequenced, seven rat connexins that previously were unavailable. The expression of connexin genes was examined in some hamster organs and cultured hamster cells, and compared with wild-type mouse and the cancer-prone Min mouse. Although the expression patterns were similar for most organs and connexins in hamster and mouse, there were also some prominent differences (Cx29 and 30.3 in testis; Cx31.1 and 32 in eye; Cx46 in brain, kidney and testis; Cx47 in kidney). This suggests that some connexins have species-specific expression profiles. In contrast, there were minimal differences in expression profiles between wild type and Min mice. Species-specific expression profiles should be considered in attempts to make animal models of human connexin-associated diseases.     

Phospholipase C activation in rat pituitary adenoma (GH) cells

The presence of the pertussis toxin (PTX) insensitive GTP-binding proteins (G-proteins) G_q and/or G₁₁ has been demonstrated in three different prolactin (PRL) and growth hormone (GH) producing pituitary adenoma cell lines. Immunoblocking of their coupling to hormone receptors indicates that G_q and/or G₁₁ confer throliberin (TRH) responsive phospholipase C (PL-C) activity in these cells. The contention was substantiated by immunoprecipitation analyses snowing that anti G_q/11-sera coprecipitated PL-C activity. In essence, only G_q/11 (but neither G_i2, G_i3 nor G_o) seems to mediate the TRH-sensitive PL-C activity, while G_o may be coupled to a basal or constitutive PL-C activity. Immunoblocking studies imply that the B-complex also, to some extent, may stimulate GH₃ pituitary cell line PL-C activity. Finally, the steady state levels of G_q/11 mRNA and protein were downregulated upon long term exposure of the GH3 cells to TRH (but not to vasoactive intestinal peptide = VIP).     

Epimerization of 3-hydroxy-4-trans-decenoyl coenzyme A by a dehydration/hydration mechanism catalyzed by the multienzyme complex of fatty acid oxidation from Escherichia coli.

The mechanism of 3-hydroxyacyl-CoA epimerase (EC 5.1.2.3), which is associated with the multienzyme complex of fatty acid oxidation from Escherichia coli, was studied with D-3-hydroxy-4-trans-decenoyl-CoA as a substrate. The E. coli complex catalyzes the rapid and direct dehydration of D-3-hydroxy-4-trans-decenoyl-CoA to 2-trans,4-trans-decadienoyl-CoA, which is slowly hydrated to L-3-hydroxy-4-trans-decenoyl-CoA. A kinetic analysis of the epimerase and its partial reactions established that epimerization of 3-hydroxyacyl-CoAs occurs solely by a dehydration/hydration mechanism. The results of a substrate competition study with L-3-hydroxy-4-trans-decenoyl-CoA and its D-isomer, together with the conclusion from a sequence analysis of the large subunit of the E. coli complex (Yang, X.-Y., Schulz, H., Elzinga, M., and Yang, S.-Y. (1991) Biochemistry 30, 6788-6795), prompt the suggestion that a single active site is responsible for the dehydration of the D- and L-isomers of 3-hydroxyacyl-CoAs.     

Sea trout Salmo trutta in the subarctic: home-bound but large variation in migratory behaviour between and within populations

Anadromous brown trout (sea trout), Salmo trutta, is currently in decline throughout its range, largely due to anthropogenic stressors in freshwater and marine habitats. Acoustic telmetry was utilized to study the marine migration of sea trout post-smolts from three populations in a relatively pristine subarctic fjord system. While at sea, the sea trout spent a substantial part of their time close to their natal river, preferred near shore over pelagic habitats and were strongly surface oriented. Despite a fidelity towards local areas, the sea trout utilized various parts of the fjord system, with maximum dispersion >30 km and total migration distance >300 km. Almost half of the sea trout (44%) migrated between river outlets, indicating that a metapopulation approach may be appropriate when managing neighbouring sea trout populations at high latitudes. Furthermore, the different populations displayed different migratory behaviours in terms of distance migrated, dispersion from origin and the likelihood of leaving their home area. This variation in migratory behaviour is likely influenced by spatiotemporal differences in habitat quality between sites, indicating that local habitat variations may promote population-specific behavioural responses even in relatively confined fjord systems.     

A Centipede Toxin Family Defines an Ancient Class of CSαβ Defensins

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