The complete cDNA and deduced amino acid sequences of the ribosomal protein S15a (AmphiS15a) and L19 (AmphiL19) of the amphioxus Branchiostoma belcheri tsingtauense were identified in the present study. The AmphiS15a cDNA is 540 nucleotides in length and encodes a 130 amino acid protein with a calculated molecular mass of 14.9 kDa. It shares 70-85% sequence identity to its known counterparts in the eukaryotes including human, rat, sea urchin, fruit fly and yeast. The AmphiL19 cDNA comprises 728 nucleotides and encodes a 197 amino acid protein with a calculated molecular mass of 23.4 kDa. It shows 59-79% sequence identity to the eukaryotic L19 proteins from human, rat, mouse, fruit fly, Caenorhabditis elegans and yeast. Both AmphiS15a and AmphiL19 are highly basic and contain putative nucleolar localization signals. As house-keeping genes, they may both be useful to normalize gene expression in characterization of various genes from the amphioxus.
Molecular fingerprinting using signature lipid biomarker (SLB) analysis and nucleic-acid-based techniques provides a quantitative and comprehensive method to assess the viable biomass, community composition and physiological status of microbial communities. Photosynthetic microbial mats are sedimentary structures composed primarily of different populations of bacteria in multilayered communities. Traditionally, microbial ecology studies of microbial mat communities have been incomplete because of the inability to identify and quantity all contributing populations. In fact, classical methods often revealed less than 1% of the microbial diversity. Examination of the lipid components of microbial mat samples allows a sensitive assessment of the in situ microbial community that is independent of the isolation and culture of certain microorganisms. Numerous studies based on SLB analysis of microbial mats have established a relationship between physiological activities, daily and seasonal processes and microniches within the mat. Expansion of the SLB approach and concomitant analysis of the nucleic acids derived from the lipid extraction provide a powerful tool for improving our understanding of complex microbial communities such as intertidal microbial mats.
We present the first data on copepod feeding and production in the Rio de la Plata, and discuss their correlation to the physical and biological environment. Sampling was performed at a protected area on the Montevideo coast where temperature, salinity and size fractionated chlorophyll a and phaeopigments were monitored weekly from January through February 2003, plus two additional observations in March and April. Acartia tonsa ingestion was measured by gut fluorescence, and gut evacuation rates, egg production and egg hatching success were estimated using standard methods. Food availability was moderate/high, but quality appeared low as reflected by chlorophyll a:phaeopigment ratios <1. Ingestion correlated with both chl-a and pha, suggesting that A. tonsa fed also on detrital matter. Egg production rates were low (1.4-7.5 eggs female(-1) d(-1)) - except for one exceptional record of ca. 88 eggs female(-1) d(-1) - indicating low productivity rates. Egg hatching success ranged from 30-94% and tended to increase during the study period. Overall results suggest that at the study site A. tonsa fed on both phytoplankton and detritus, and that its production was limited by food quality.
Hydrocarbons are widespread in our environment. The number of bacteria known to oxidize hydrocarbons in the absence of oxygen has considerably increased during the last ten years. Anaerobic bacteria have been shown capable of utilizing hydrocarbons not only in consortia but also in pure Cultures. The results obtained in the framework of MATBIOPOL project on anaerobic hydrocarbon degradation by denitrifying bacteria and by enrichment cultures maintained under methanogenic conditions are exposed together with the present knowledge on hydrocarbon biodegradation.
A helpful new tool has just recently become available to people involved with polychaete identification — specialists and non-specialists alike. A CD packed with information on polychaetes, bu, primarily a tool to identify them interactively. The editors are a strong Australian team of well known polychaete researchers and further contributions to the CD come from other significant figures inside and outside of Australia.
