Pyrrole analogues of the pyrrolidinone moiety of the potassium channel activator cromakalim as relaxants of guinea pig trachealis.

A series of C-4 pyrrole substituted benzopyrans and benzopyranols has been prepared, some members of which are potent relaxants of guinea pig trachealis in vitro. These compounds appear to act via potassium channel opening. It is envisaged that a pyrrole ring substituted with an electron-withdrawing group can function as a bioisostere of the pyrrolidinone of cromakalim. Two tetracyclic derivatives have been also prepared, one of which (18) appears to act as a potassium channel activator in a similar manner to cromakalim while the other (15), although a potent relaxant of guinea pig trachealis, has a profile which is inconsistent with this mechanism of action.     

Screening of Feral Pigeon (Colomba livia), Mallard (Anas platyrhynchos) and Graylag Goose (Anser anser) Populations for Campylobacter spp., Salmonella spp., Avian Influenza Virus and Avian Paramyxovirus

A total of 119 fresh faecal samples were collected from graylag geese migrating northwards in April. Also, cloacal swabs were taken from 100 carcasses of graylag geese shot during the hunting season in August. In addition, samples were taken from 200 feral pigeons and five mallards. The cultivation of bacteria detected Campylobacter jejuni jejuni in six of the pigeons, and in one of the mallards. Salmonella diarizona 14:k:z53 was detected in one graylag goose, while all pigeons and mallards were negative for salmonellae. No avian paramyxovirus was found in any of the samples tested. One mallard, from an Oslo river, was influenza A virus positive, confirmed by RT-PCR and by inoculation of embryonated eggs. The isolate termed A/Duck/Norway/1/03 was found to be of H3N8 type based on sequence analyses of the hemagglutinin and neuraminidase segments, and serological tests. This is the first time an avian influenza virus has been isolated in Norway. The study demonstrates that the wild bird species examined may constitute a reservoir for important bird pathogens and zoonotic agents in Norway.     

Using Genetic Tools to Track Desert Bighorn Sheep Colonizations

ABSTRACT Understanding colonization is vital for managing fragmented populations. We employed mitochondrial DNA haplotypes and 14 microsatellite (nuclear DNA) markers to infer the origins of newly established populations of desert bighorn sheep (Ovis canadensis nelsoni) and to assess loss of genetic diversity during natural colonizations. We used haplotype distribution, F-statistics, Bayesian population clustering, and assignment tests to infer source populations for 3 recent colonies and identified a previously undetected colonization from multiple source populations. Allelic richness declined in 3 of 4 colonies in comparison to the primary source populations, but not as much as has been reported for translocated populations. Heterozygosity declined in only one colony. We also demonstrated that both native and translocated desert bighorn sheep have naturally recolonized empty habitats and suggest that colonization may partially offset population extinction in the region as long as connectivity is maintained. Genetic techniques and mitochondrial DNA haplotypes we described will allow managers to determine the origins of future colonizations by bighorn sheep in California, USA, and prioritize protection of linkages between known sources and colonies.     

Properties of Extracellular Enzymes from Aphanomyces astaci and Their Relevance in the Penetration Process of Crayfish Cuticle

In culture filtrates from the crayfish plague parasite, Aphanomyces astaci, protease and a low level of hyaluronidase activity were found. The hyaluronidase activity was highest at pH 6.5 or above and at about 23°C. The protease activity had a broad pH-optimum, between pH 7 and at least pH 10, and was partially denatured at 30°C. However, when incubated for 30 min with the substrate, casein, the activity increased logarithmically up to about 35–40°C and had an apparent optimum at 45–50°C. The proteases from the parasitic as well as from two less proteolytic, saprophytic Aphanomyces species were predominantly constitutive and were excreted mainly by the older mycelia. Proteases from the parasite and a saprophyte did not reach full activity until 10–30 min after substrate addition. No lipase activity was found in the case of the mycelium of the parasitic species. However, esterase was apparently present inside germinating zoospores. The native enzymes of A. astaci could degrade freeze-dried soft cuticle from crayfish. The relevance of the different enzymes of A. astaci for the penetration process within the cuticle of crayfish is discussed.     

Catalysis of oxygen-18 exchange between inorganic phosphate and water by the gastric H,K-ATPase

The gastric H,K-ATPase is shown to catalyze 18O exchange between Pi and HOH. Mg2+ is the only ion required for the reaction. K+ increases the rate of isotope exchange, which is directly proportional to specific ATPase activity. Ouabain, which potently inhibits the Na,K-ATPase, has no effect on the exchange reaction. Conversely, omeprazole, which is specific for the H,K-ATPase, completely inhibits 18O exchange. Vanadate inhibition of exchange can be explained by competitive binding with Pi. The rate of 18O exchange is faster than the hydrolytic rate and about equal to the dephosphorylation rate. Thus, the ionic requirements for exchange, inhibition of exchange, and the rate of exchange are all compatible with catalysis occurring via the same phosphoenzyme intermediate formed during hydrolysis of ATP. The distribution of 18O-labeled Pi species formed with time indicates that Pi loss is only about twice as fast as covalent bond formation. This kinetic pattern is unaffected by K+, temperature, or the specific activity of the enzyme preparation. Invariance of the kinetic pattern could mean isotope exchange is always catalyzed by the same form of the enzyme, and K+ and higher temperature accelerate the reaction by increasing the relative amount of the active conformer. Independence of the kinetic pattern from specific activity implies that the catalytic mechanism of active enzyme molecules is unaffected by inactive proteins in gastric microsomal membranes.