Two new dimorphic soft-coral species (Anthozoa: Octocorallia) from Antarctica

Sphaeralcyon shackletonisp. nov. and Sphaeralcyon scottisp. nov. are described and illustrated from material collected at the Scotia Sea and Weddell Sea on the Polarstern cruises ANT XIX/3 (ANDEEP-I), ANT XIX/5 (LAMPOS), and ANT XXI/2 (BENDEX). With the discovery of Sphaeralcyon shackletoni and S. scotti, three species are now known in the genus Sphaeralcyon, all them reported from the Southern Ocean. The diagnosis of the genus has been slightly modified to accommodate some of the characters of the new species.     

Benthic suspension feeders: their paramount role in littoral marine food webs

In recent years, particular attention has been paid to coupling and energy transfer between benthos and plankton. Because of their abundance, certain benthic suspension feeders have been shown to have a major impact in marine ecosystems. They capture large quantities of particles and might directly regulate primary production and indirectly regulate secondary production in littoral food chains. Suspension feeders develop dense, three-dimensional communities whose structural complexity depends on flow speed. It has been postulated that these communities can self-organize to enhance food capture and thus establish boundary systems capable of successfully exploiting a less structured system, namely, the plankton.     

Small-scale spatial heterogeneity and seasonal variation in a population of a cave-dwelling Mediterranean mysid

Seasonal changes in small-scale spatial distribution patternsof abundance and composition of Hemimysis speluncola Ledoyer(1963) (Crustacea, Mysidacea) were studied in a population ofcave-dwelling mysids off the Medes Islands (NW MediterraneanSea). The distribution pattern was characterized all year roundby marked spatial segregation of juveniles, which occupied areascloser to the cave entrance, while adults were concentratedmainly in the innermost part of the cave. The small-scale spatialheterogeneity observed appears to be regulated by biologicalfactors, particularly social and reproductive behaviour. Nevertheless,a certain adaptation of the distribution of the swarms to hydrodynamicfactors suggests that physical factors may also play a role.The heterogeneous aggregation pattern recorded would clearlyappear to be an adaptive strategy by the population to enableit to thrive within its habitat. That adaptation is designedto reduce predation mortality, enhance mating efficiency andregulate the population generally. Marked seasonal fluctuationsin the density and composition of the population were recorded,with high density levels in winter and throughout the spring.Two methods were employed to quantify the population: haulswith plankton nets towed by divers and collection of faecalpellets. The patterns observed using both these methods weresimilar, although the latter method yielded total density valuesthat were an order of magnitude greater.     

Plant phenylacetaldehyde synthase is a bifunctional homotetrameric enzyme that catalyzes phenylalanine decarboxylation and oxidation

We have isolated and characterized Petunia hybrida cv. Mitchell phenylacetaldehyde synthase (PAAS), which catalyzes the formation of phenylacetaldehyde, a constituent of floral scent. PAAS is a cytosolic homotetrameric enzyme that belongs to group II pyridoxal 5'-phosphate-dependent amino-acid decarboxylases and shares extensive amino acid identity (approximately 65%) with plant L-tyrosine/3,4-dihydroxy-L-phenylalanine and L-tryptophan decarboxylases. It displays a strict specificity for phenylalanine with an apparent Km of 1.2 mM. PAAS is a bifunctional enzyme that catalyzes the unprecedented efficient coupling of phenylalanine decarboxylation to oxidation, generating phenylacetaldehyde, CO2, ammonia, and hydrogen peroxide in stoichiometric amounts.     

Interference between Streptococcus pneumoniae and Staphylococcus aureus: In vitro hydrogen peroxide-mediated killing by Streptococcus pneumoniae

The bactericidal activity of Streptococcus pneumoniae toward Staphylococcus aureus is mediated by hydrogen peroxide. Catalase eliminated this activity. Pneumococci grown anaerobically or genetically lacking pyruvate oxidase (SpxB) were not bactericidal, nor were nonpneumococcal streptococci. These results provide a possible mechanistic explanation for the interspecies interference observed in epidemiologic studies.     

The phage‐driven microbial loop in petroleum bioremediation

During the drilling process and transport of crude oil, water mixes with the petroleum. At oil terminals, the water settles to the bottom of storage tanks. This drainage water is contaminated with emulsified oil and water-soluble hydrocarbons and must be treated before it can be released into the environment. In this study, we tested the efficiency of a continuous flow, two-stage bioreactor for treating drainage water from an Israeli oil terminal. The bioreactor removed all of the ammonia, 93% of the sulfide and converted 90% of the total organic carbon (TOC) into carbon dioxide. SYBR Gold staining indicated that reactor 1 contained 1.7 × 10⁸ bacteria and 3.7 × 10⁸ phages per millilitre, and reactor 2 contained 1.3 × 10⁸ bacteria and 1.7 × 10⁹ phages per millilitre. The unexpectedly high mineralization of TOC and high concentration of phage in reactor 2 support the concept of a phage-driven microbial loop in the bioremediation of the drainage water. In general, application of this concept in bioremediation of contaminated water has the potential to increase the efficiency of processes.