Rapid classification of bacterial strains by SDS-polyacrylamide gel electrophoresis: population dynamics of the dominant dispersed phase bacteria of activated sludge

Summary Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of total cellular proteins has been used to classify bacterial strains of the dispersed phase of activated sludge. The dominant bacterial populations are shown to be in dynamic change at species level while higher order taxons are more stable.     

An enzymatic transglycosylation of purine bases

An enzymatic transglycosylation of purine heterocyclic bases employing readily available natural nucleosides or sugar-modified nucleosides as donors of the pentofuranose fragment and recombinant nucleoside phosphorylases as biocatalysts has been investigated. An efficient enzymatic method is suggested for the synthesis of purine nucleosides containing diverse substituents at the C6 and C2 carbon atoms. The glycosylation of N(6)-benzoyladenine and N(2)-acetylguanine and its O(6)-derivatives is not accompanied by deacylation of bases.     

Neuronostatin, a novel peptide encoded by somatostatin gene, regulates cardiac contractile function and cardiomyocyte survival

Neuronostatin, a recently discovered peptide encoded by somatostatin gene, is involved in regulation of neuronal function, blood pressure, food intake, and drinking behavior. However, the biological effects of neuronostatin on cardiac myocytes are not known, and the intracellular signaling mechanisms induced by neuronostatin remain unidentified. We analyzed the effect of neuronostatin in isolated perfused rat hearts and in cultured primary cardiomyocytes. Neuronostatin infusion alone had no effect on left ventricular (LV) contractile function or on isoprenaline- or preload-induced increase in cardiac contractility. However, infusion of neuronostatin significantly decreased the positive inotropic response to endothelin-1 (ET-1). This was associated with an increase in phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK). Treatment of both neonatal and adult cardiomyocytes with neuronostatin resulted in reduced cardiomyocyte viability. Inhibition of JNK further increased the neuronostatin-induced cell death. We conclude that neuronostatin regulates cardiac contractile function and cardiomyocyte survival. Receptors for neuronostatin need to be identified to further characterize the biological functions of the peptide.     

Synergistic activation of salmon cardiac function by endothelin and beta-adrenergic stimulation

The aim was to find out the effects of endothelin-1 (ET-1) in salmon (Salmo salar) cardiac contractile and endocrine function and its possible interaction with beta-adrenergic regulation. We found that ET-1 has a positive inotropic effect in salmon heart. ET-1 (30 nM) increased the contraction amplitude 17+/-4.7% compared with the basal level. beta-Adrenergic activation (isoprenaline, 100 nM) increased contraction amplitude 30+/-13.1%, but it did not affect the contractile response to ET-1. ET-1 (10 nM) stimulated the secretion of salmon cardiac natriuretic peptide (sCP) from isolated salmon ventricle (3.3+/-0.14-fold compared with control) but did not have any effect on ventricular sCP mRNA. Isoprenaline alone (0.1-1,000 nM) did not stimulate sCP release, but ET-1 (10 nM) together with isoprenaline (0.1 nM) caused a significantly greater increase of sCP release than ET-1 alone (5.4+/-0.07 vs. 3.3+/-0.14 times increase compared with control). The effects on the contractile and secretory function could be inhibited by a selective ETA-receptor antagonist BQ-610 (1 microM), whereas ETB-receptor blockage (by 100 nM BQ-788) enhanced the secretory response. Thus ET-1 is a phylogenetically conserved regulator of cardiac function, which has synergistic action with beta-adrenergic stimulation. The modulatory effects of ET-1 may therefore be especially important in situations with high beta-adrenergic tone.     

An introduction of a pyridine group into the structure of prolyl oligopeptidase inhibitors

A series of ionizable prolyl oligopeptidase inhibitors were developed through the introduction of a pyridyl group to the P3 position of the prolyl oligopeptidase inhibitor structure. The study was performed on previously developed prolyl oligopeptidase inhibitors with proline mimetics at the P2 position. The 3-pyridyl group resulted in equipotent compounds as compared to the parent compounds. It was shown that the pyridyl group improves water solubility and, in combination with a 5(R)-tert-butyl-l-prolyl group at the P2 position, good lipophilicity can be achieved.     

Fixed Rejection Responses to Single and Multiple Experimental Parasitism in Two Fringilla Hosts of the Common Cuckoo

Previous studies have shown that the tendency to reject parasitic eggs among certain hosts is strongly dependent on the degree of similarity with own eggs, whereas other conditional cues do not affect rejection decisions. This paper examines whether two such hosts, the closely related brambling and chaffinch, show a different tendency to reject parasitic eggs if they are multiply parasitized. Some individuals were experimentally parasitized with both a non-mimetic and a low–intermediate contrasting egg in the same breeding attempt. The non-mimetic egg was rejected almost without exception. In chaffinches, the low–intermediate contrasting egg was introduced shortly after rejection of the non-mimetic egg whereas in bramblings, both eggs were introduced simultaneously. A control group consisted of individuals that were parasitized with one low–intermediate contrasting egg. There was no significant difference in the tendency to reject the low–medium contrasting eggs between the experimental and control group in any of the species, implying that the same acceptance threshold is applied to each parasitic egg independently. Moreover, the rejection rate of non-mimetic eggs was high (>90%) regardless of whether the egg was introduced alone or together with a low–medium contrasting egg. The results are discussed in relation to recent studies with great reed warblers Acrocephalus arundinaceus that obtained contrasting results in similar experimental designs. The different degrees of flexibility displayed by Fringilla and great reed warbler hosts are likely to reflect differences in both the perception and action component of the recognition system.     

Do parasitic common goldeneye Bucephala clangula females choose nests on the basis of host traits or nest site traits?

Conspecific brood parasitism (CBP) is an important alternative breeding strategy for gaining reproductive output in birds. While interactions between hosts and parasites and consequences of CBP to breeding success of both parties have been studied a lot, the roles of host characteristics and nest site characteristics in CBP have received less attention. We studied the relative importance of host‐related traits, such as female condition and breeding experience, and nest‐site‐related factors, such as overall nest site preference and occupation rate, in explaining the occurrence of CBP in a common goldeneye Bucephala clangula population. We used spatially and temporally extensive data sets, analysed the data with generalized linear mixed models that allowed us to account for the non‐independency of individual nesting attempts across females and nesting sites, and used an information theoretic approach in model selection and inference. About half of the nests were parasitized annually during the seven year study period. The occurrence of CBP decreased with advancement of the breeding season but late nests were also frequently parasitized. We found that the occurrence of CBP was better explained by nest‐site characteristics than host traits, implying that parasitic females target a given nest based on factors related to the nest site itself rather than on the host. Our results suggest that more attention should be paid to factors associated with nest site attractiveness and quality when studying laying decisions of parasites and the occurrence of CBP in general.     

Evolution of defences against cuckoo (<Emphasis Type="Italic">Cuculus canorus</Emphasis>) parasitism in bramblings (<Emphasis Type="Italic">Fringilla montifringilla</Emphasis>): a comparison of four populations in Fennoscandia

The brood parasitic common cuckoo Cuculus canorus has a history of coevolution that involves numerous passerine hosts, but today only a subset is known to be regularly parasitised in any area. In some hosts, there is significant variation in the occurrence of parasitism between populations, but still individuals in non-parasitised populations show strong antiparasite defences. In the present study we compared the strength of egg rejection of four distant Fennoscandian brambling Fringilla montifringilla populations experiencing different levels of cuckoo parasitism (0–6%). Egg rejection ability was in general very well developed and we did not find any population differences in the relationship between egg rejection probability and similarity between host and experimental parasitic eggs. Furthermore, bramblings very rarely made errors in rejection, indicating that selection against rejection behaviour is likely to be very weak. The brambling-cuckoo system therefore differs from other well studied systems which are characterised by pronounced spatial and temporal variation in the host’s level of defence. This result is unlikely to reflect independent replication of the same evolutionary trajectory because the weak breeding site tenacity of bramblings should result in an extreme amount of gene flow within the distribution area and thus strongly impede localised responses to selection. Instead, lack of geographic variation has more likely arisen because bramblings respond to selection as one evolutionary unit, and because the average parasitism pressures have been high enough in the past to cause regional fixation of rejection alleles and evolution of clutch characteristics that facilitate cost free egg recognition.     

Design,synthesis and in vitro/in vivo evaluation of orally bioavailable prodrugs of a catechol-O-methyltransferase inhibitor

Compound 1 is an investigational, nanomolar inhibitor of catechol-O-methyltransferase (COMT) that suffers from poor oral bioavailability, most probably due to its low lipophilicity throughout most of the gastrointestinal tract and, to a lesser extent, its rapid systemic clearance. Several lipophilic esters were designed as prodrugs and synthesized in an attempt to optimize presystemic drug absorption. A modest twofold increase in 6-h exposure of 1 was observed with two prodrugs, compared to that of 1, after oral treatment in rats.