Plasticity in the effects of sulfated and nonsulfated sulfakinin on heart contractions.

Neuropeptides regulate the frequency of heart contractions. Drosophila melanogaster sulfakinin (drosulfakinin) encodes FDDYGHMRFamide, DSK I, and GGDDQFDDYGHMRFamide, DSK II. Invertebrate sulfakinins are structurally and functionally related to vertebrate cholecystokinins. Naturally-occurring drosulfakinins contain a sulfated or nonsulfated tyrosine and are designated sDSK I, sDSK II, nsDSK I, and nsDSK II. We developed a novel neural-cardiovascular preparation and investigated mechanisms regulating the effect of sulfakinins on D. melanogaster heart. We established the preparation in larva, pupa, and adult to examine plasticity in neural regulation of cardiovascular parameters. We discovered sDSK I increased the frequency of larval, pupal, and adult heart contractions; nsDSK I only increased the frequency of larval contractions, not pupal or adult. We also discovered sDSK II and nsDSK II increased the frequency of larval and adult contractions, not pupal. This is the first report of nonsulfated sulfakinin activity on heart, and sulfakinin activity examined in 3 developmental stages within the same animal species. Our data demonstrate a role for plasticity in the effects of sulfakinins on heart contractions, and suggest multiple mechanisms are involved.

A putative glucan synthase gene dps detected in exopolysaccharide-producing Pediococcus damnosus and Oenococcus oeni strains isolated from wine and cider.

Some lactic acid bacteria can induce viscosity in wine, beer and cider by production of exopolysaccharides (EPS). A polymerase chain reaction (PCR) assay was previously described for the detection of ropy Pediococcus damnosus strains in wine [J. Appl. Microbiol. 90 (2001) 535]. The primers used in that study, PF5 and PF6, are investigated in addition to new primers which broaden the range of spoiling agents detectable by PCR. Primers PF1 and PF8 allow the amplification of DNA from ropy P. damnosus strains isolated from wine, as was observed with PF5 and PF6. In addition, PF1 and PF8, unlike PF5 and PF6, are able to generate an amplicon using template DNA from a ropy P. damnosus strain isolated from cider and a ropy Oenococcus oeni strain isolated from champagne. Two different ropy Lactobacillus species were also isolated, but their DNA was not amplified using primers PF1 and PF8. The new primers PF1 and PF8 were chosen from the sequence of gene dps, a putative glucan synthase gene, found across all the ropy P. damnosus strains isolated, from both wine or cider, and also in a ropy O. oeni strain. To our knowledge, this is the first time that an EPS-producing O. oeni strain is described. Glucan biosynthesis was assessed by agglutination tests done with Streptococcus pneumoniae type 37-specific antibodies, which specifically detect glucan-producing cells. The results show that there is a direct correlation between glucan production and detection of gene dps. Therefore, Dps is considered a candidate for the glucan synthase enzyme responsible for EPS production by ropy strains of P. damnosus and O. oeni.