Markus Haber

Coloration and Defense in the Nudibranch Gastropod Hypselodoris fontandraui

The striking color patterns of chromodorid (and other) nudibranchs appear to be indicative of aposematism. In Müllerian mimicry, all the mimic species have a defense mechanism. It has been proposed that a group of blue, white, and yellow Mediterranean and northeastern Atlantic species of the genus Hypselodoris form a Müllerian mimetic circle. One of these, H. fontandraui, lacks the mantle dermal formations (repugnatorial glands) that are typically found in other members of this circle and are reservoirs of feeding deterrent compounds. It therefore seemed possible that this animal lacks chemical defense and acts like a Batesian mimic. Within this study, we found that this nudibranch contains the furanosesquiterpenoid tavacpallescensin, most probably derived from sponges of the genus Dysidea, upon which it probably feeds. The metabolite concentrations were measured from samples of the mantle rim, other external parts, and internal organs. Concentrations were about 4 times higher in the mantle rim than in the other external parts, and more than 20 times higher in the mantle rim than in the internal organs, considerably exceeding the threshold value of concentration showing the maximum dose effect as feeding deterrent against the crustacean Palaemon elegans. In conclusion, the reported data clearly demonstrate that H. fontandraui is chemically defended in much the same way as its aposematic, co-occurring, and blue-colored congeners within the Müllerian mimetic circle and is not a Batesian mimic.

Diversity and antibacterial activity of bacteria cultured from Mediterranean Axinella spp. sponges

Evaluation of the diversity and antibacterial activity of bacteria cultivated from Mediterranean Axinella sponges and investigating the influence of culture conditions on antibacterial activity profiles of sponge bacteria.

Aureivirga marina gen. nov., sp. nov., a marine bacterium isolated from the Mediterranean sponge Axinella verrucosa.

Two bacterial strains, VI.14 and VIII.04(T), were isolated from the Mediterranean sponge Axinella verrucosa collected off the Israeli coast near Sdot Yam. The non-motile, aerobic, Gram-negative isolates were oxidase-negative and catalase-positive, and formed golden-brown colonies on marine agar 2216. The pigment was neither diffusible nor flexirubin-like. Strain VIII.04(T) grew at 15-37 °C, at pH 6.0-9.0, in the presence of 20-50 g NaCl l(-1) and 20-80 g sea salts l(-1), The spectrum was narrower for strain VI.14, with growth at pH 7.0-8.0. and in the presence of 30-50 g NaCl l(-1) and 30-70 g sea salts l(-1). The predominant fatty acid (>50 %) in both strains was iso-C15 : 0, and the major respiratory quinone was MK-6. The DNA G+C content was 30.7 and 31.1 mol% for VIII.04(T) and VI.14, respectively. Results from 16S rRNA sequence similarity and phylogenetic analyses indicated that both strains are closely related to members of the family Flavobacteriaceae within the phylum Bacteroidetes, with as much as 91.7 % 16S rRNA sequence similarity. On the basis of data from the polyphasic analysis, we suggest that the strains represent a novel species in a new genus within the family Flavobacteriaceae, for which the name Aureivirga marina gen. nov., sp. nov. is proposed. Strain VIII.04(T) ( = ATCC BAA-2394(T) = LMG 26721(T)) is the type strain of Aureivirga marina.

Chemical Defense Against Fouling in the Solitary Ascidian Phallusia nigra

The solitary ascidian Phallusia nigra is rarely fouled by epibionts. Here, we tested the antifouling activity of its crude extracts in laboratory and field assays. P. nigra extracts inhibited the growth of all eight tested environmental bacteria and two of four laboratory bacteria. Extracts of the sympatric, but fouled solitary ascidian Herdmania momus inhibited only one test bacterium. Scanning electron microscopy confirmed that the tunic surface of P. nigra is largely bacteria-free. Both ascidian extracts significantly inhibited the larval metamorphosis of the bryozoan Bugula neritina at the tested concentration range of 0.05–2 mg ml−1. Both crude extracts were toxic to larvae of the brine shrimp Artemia salina at natural volumetric whole-tissue concentrations, but only P. nigra showed activity at 2 mg ml−1 and below (LC50 = 1.11 mg ml−1). P. nigra crude extracts also significantly reduced the settlement of barnacles, polychaetes, and algae in Mediterranean field assays and barnacle settlement in Red Sea trials. Comparisons between control experiments and pH values monitored in all experiments indicate that the observed effects were not due to acidity of the organic extracts. Our results show that P. nigra secondary metabolites have antifouling activities, which may act in synergy with previously proposed physiological antifouling mechanisms.

Fulvitalea axinellae gen. nov., sp. nov., a member of the family Flammeovirgaceae isolated from the Mediterranean sponge Axinella verrucosa

The yellow-pigmented, non-motile, Gram-negative, strictly aerobic, rod-shaped bacterial strain VI.18(T) was isolated from the Mediterranean sponge Axinella verrucosa collected off the coast near Sdot Yam, Israel. Results from 16S rRNA gene sequence analysis indicated that the isolate belonged to the family Flammeovirgaceae. The highest nucleotide similarity (91.4 %) occurred with Aureibacter tunicatorum A5Q-118(T). The predominant cellular fatty acids of strain VI.18(T) were iso-C15 : 0 (56.0 %), iso-C17 : 1ω9c (22.8 %) and C16 : 0 (7.4 %) and its major respiratory quinone was MK-7. The DNA G+C content was 47.5 mol%. The strain could readily be distinguished from its phylogenetically closest relatives by phenotypic, physiological and chemotaxonomic properties. On the basis of the data from the present polyphasic study, we propose a novel genus and species within the family Flammeovirgaceae, with the name Fulvitalea axinellae gen. nov., sp. nov. Strain VI.18(T) ( = ATCC BAA-2395(T)  = LMG 26722(T)) is the type strain of Fulvitalea axinellae.

Luteivirga sdotyamensis gen. nov., sp. nov., a novel bacterium of the phylum Bacteroidetes isolated from the Mediterranean sponge Axinella polypoides.

A novel aerobic bacterium, designated strain PIII.02(T), was isolated from a Mediterranean sponge (Axinella polypoides) collected off the Israeli coast near Sdot Yam. The non-motile cells were Gram-staining-negative, oxidase-positive and catalase-positive. The orange pigment of colonies growing on marine agar was neither diffusible nor flexirubin-like. Strain PIII.02(T) grew at 15-35 °C, at pH 6.0-9.0, with 2.0-7.0 % (w/v) NaCl, and with 1.0-8.0 % (w/v) sea salts. The predominant fatty acids were iso-C15 : 0, iso-C16 : 1 H, iso-C16 : 0, C16 : 0, anteiso-C15 : 0 and C16 : 1ω7c. The major respiratory quinone was MK-7. The genomic DNA G+C content of the novel strain was 38.1 mol%. Results from 16S rRNA gene sequence analysis indicated that strain PIII.02(T) was distantly related to established members of the phylum Bacteroidetes. The established species found to be most closely related to the novel strain was Persicobacter diffluens NCIMB 1402(T) (87.6 % 16S rRNA gene sequence similarity). Based on the phenotypic and chemotaxonomic data and the results of the phylogenetic analyses, strain PIII.02(T) represents a novel species of a new genus, for which the name Luteivirga sdotyamensis gen. nov., sp. nov. is proposed. The type strain is PIII.02(T) ( = ATCC BAA-2393(T)  = LMG 26723(T)).