Antimicrobial Activity of Small Synthetic Peptides Based on the Marine Peptide Turgencin A: Prediction of Antimicrobial Peptide Sequences in a Natural Peptide and Strategy for Optimization of Potency.

Turgencin A, a potent antimicrobial peptide isolated from the Arctic sea squirt Synoicum turgens, consists of 36 amino acid residues and three disulfide bridges, making it challenging to synthesize. The aim of the present study was to develop a truncated peptide with an antimicrobial drug lead potential based on turgencin A. The experiments consisted of: (1) sequence analysis and prediction of antimicrobial potential of truncated 10-mer sequences; (2) synthesis and antimicrobial screening of a lead peptide devoid of the cysteine residues; (3) optimization of in vitro antimicrobial activity of the lead peptide using an amino acid replacement strategy; and (4) screening the synthesized peptides for cytotoxic activities. In silico analysis of turgencin A using various prediction software indicated an internal, cationic 10-mer sequence to be putatively antimicrobial. The synthesized truncated lead peptide displayed weak antimicrobial activity. However, by following a systematic amino acid replacement strategy, a modified peptide was developed that retained the potency of the original peptide. The optimized peptide StAMP-9 displayed bactericidal activity, with minimal inhibitory concentrations of 7.8 µg/mL against Staphylococcus aureus and 3.9 µg/mL against Escherichia coli, and no cytotoxic effects against mammalian cells. Preliminary experiments indicate the bacterial membranes as immediate and primary targets.

Vibrio echinoideorum sp. nov., isolated from an epidermal lesion on the test of a green sea urchin (Strongylocentrotus droebachiensis).

A Gram-stain-negative, facultatively anaerobic Vibrio strain, designated NFH.MB010T, was isolated from an epidermal lesion on the test (hard shell skeleton) of a green sea urchin (Strongylocentrotus droebachiensis) collected from northern Norway. Cells of strain NFH.MB010T were rod shaped and motile by means of a single, long polar flagellum. Growth was observed at 1-5% NaCl (w/v) and at 4 °C, but not above 28 °C. Phylogenetic analyses based on eight-gene multilocus sequence analysis (16S rRNA, atpA, gyrB, mreB, pyrH, recA, rpoA and rpoD) suggested novelty at the species level. In silico DNA-DNA hybridization and orthologous average nucleotide identity estimates showed percentage genomic resemblances to its closest relative, Vibrio splendidus, that were well below the established same species threshold values. Phenotypically, utilization of glycogen and gentiobiose, inability of acetoin production, and undetectable valine arylamidase and trypsin activity discriminated strain NFH.MB010T from the closely related reference strains. Protein spectra generated by maldi-tof mass spectrometry further consolidated the species level uniqueness of strain NFH.MB010T. Based on the described polyphasic approach, strain NFH.MB010T therefore appears as a novel species within the Splendidus clade of the genus Vibrio, and the name Vibrio echinoideorum sp. nov. is proposed, with NFH.MB010T (=DSM 107264T=LMG 30656T) as the type strain.

A wax ester and astaxanthin-rich extract from the marine copepod Calanus finmarchicus attenuates atherogenesis in female apolipoprotein E-deficient mice.

The aim of this study was to investigate the effect of dietary supplementation with an oil extracted from the zooplankton copepod Calanus finmarchicus [calanus oil (CO)] on atherosclerosis in apoE-deficient (apoE(-/-)) mice. Thirty 6-wk-old female apoE(-/-) mice (n = 10/group) were fed: 1) a Western-type, high-fat diet (HFD); 2) HFD supplemented with 1% (wt:wt) CO; or 3) HFD supplemented with 0.88% (wt:wt) corn oil + 0.12% (wt:wt) EPA+DHA ethyl esters (EPA+DHA) for 13 wk. Dietary CO supplementation lowered total aorta atherogenesis by 36.5% compared to the HFD (P < 0.01), whereas the reduction in the lesion prone aortic arch was 34.8% (P < 0.01). The degree of aortic atherogenesis was intermediate in mice fed EPA+DHA compared to those fed HFD and CO. The effect on atherogenesis was paralleled by reduced expression of hepatic genes for the proinflammatory cytokines, Ccl2, Icam1, Il1b, and Nfkb1, in mice fed CO compared to those fed HFD. For mice fed EPA+DHA, gene expression did not differ compared to those fed CO or HFD. Plasma concentrations of total cholesterol, TG, and cytokines did not differ between the groups at the end of the study. However, mice fed CO gained more weight compared to those fed HFD but not compared to those fed EPA+DHA. In conclusion, dietary CO supplementation attenuated atherosclerotic lesion formation in female apoE(-/-) mice and may be an effective and safe dietary intervention to reduce the development of atherosclerosis. However, further studies are warranted to elucidate the underlying physiological and molecular mechanisms.