Preliminary study on the occurrence of brominated organic compounds in Dutch marine organisms

The extracts of three marine organisms; the ascidian Ciona intestinalis, the brown seaweed Sargassum muticum and the sponge Halichondria panicea, all elicited a number of brominated compounds, some of which were tentatively identified. Tribromophenol was observed in all species. This compound, also industrially produced as flame retardant and fungicide, was likely due to endogenous production.     

HSP70 heat shock proteins and environmental stress in Antarctic marine organisms: A mini-review

The ability to understand and predict the effects of environmental stress on biodiversity is becoming increasingly important in our changing environment. Antarctic marine species are some of the most stenothermal on the planet and many inhabit the waters off the Antarctic Peninsula which is one of the areas where there is rapid regional climate change. Therefore these animals are highly vulnerable to changing environmental temperatures and clearly we need to understand the complexities of their response, not just at the individual species level, but also the implications for the ecosystem as a whole. Heat shock proteins have a long history of use in studies of organism stress responses and have frequently been proposed as potential universal molecular biomarkers, especially for non-model species. In this mini-review, the heat shock response and heat shock proteins (specifically the HSP70 family) are examined in Antarctic marine species alongside their physiological capabilities and limits to answer a series of questions: do these animals have a heat shock response which includes the expression of HSP70 genes? What is the relationship between their heat shock response and physiological capabilities? Can HSP70 genes be used as molecular biomarkers for these species?     

The significance of fish in the marine Antarctic ecosystems

Paper presented at the Symposium on Polar regions: the challenge for biological and ecological research organised by the Swiss Committee for Polar Research, Basel on 2 October 1992     

The biodiversity of macrofaunal organisms in marine sediments

Marine sediments cover most of the ocean bottom, and the organisms that reside in these sediments therefore constitute the largest faunal assemblage on Earth in areal coverage. The biomass in these sediments is dominated by macrofauna, a grouping of invertebrate polychaetes, molluscs, crustaceans and other phyla based on size. Globally, only a small portion of marine habitats have been sampled for macrofauna, but sampled areas have led to global estimates of macrofaunal species number ranging from 500,000 to 10,000,000. Most of these species are undescribed, and global syntheses of patterns of individual taxa and biodiversity are few and based on limited samples. The significance of biodiversity in marine sediments to ecosystem processes is poorly understood, but individual species and functional groups are known to carry out activities that have global importance. Macrofaunal activity impacts global carbon, nitrogen and sulphur cycling, transport, burial and metabolism of pollutants, secondary production including commercial species, and transport of sediments. Documented extinctions of marine macrofauna are few, but the ramifications of species loss through habitat shrinkage and undocumented extinctions are unknown. Limited data suggest there is substantial functional redundancy in macrofauna within trophic groups but whether this redundancy is sufficient to allow species loss without significantly altering ecosystem processes is unknown. Sorely needed are experiments that test specific hypotheses on biodiversity, redundancy, and ecosystem processes as they relate to marine macrofauna.     

The occurrence of hopanoid lipids in Bradyrhizobium bacteria

Abstract Lipid extraction procedures followed by GLC and GLC-MS analysis were used to investigate the triterpenoid content in Bradyrhizobium and Rhizobium bacteria. Unlike the tested strains of Rhizobium bacteria, a range of triterpenoids e.g., squalene and different classes of hopanoid derivatives were detected in bacteria from all Bradyrhizobium strains investigated (different strains from Bradyrhizobium japonicum, Bradyrhizobium elkanii as well as Bradyrhizobium sp.). Furthermore, related compounds were identified from some hopanoid lipids (e.g., diplopterol) that carried an additional methyl group in their molecular structure. The hopanoid content was high in some strains and accounted for more than 40% of the total lipid fraction (e.g., in strains Bradyrhizobium japonicum USDA 110 and USDA 31), while other strains contained only about a tenth of that amount (e.g., Bradyrhizobium japonicum ATCC 10324 and Bradyrhizobium sp. ( Lupinus ) ATCC 10319).     

Coexisting role of fasting or feeding and dietary lipids in the control of gene expression of enzymes involved in the synthesis of saturated, monounsaturated and polyunsaturated fatty acids

In the liver, maintaining lipid homeostasis is regulated by physiological and exogenous factors. These lipids are synthesized by Fasn, elongases and desaturases. Interactions in an organism among these factors are quite complex and, to date, relatively little is known about them. The aim of this study was to evaluate the coexisting role of physiological (insulin, fasting and feeding) and exogenous (dietary lipids) factors in the control of gene expression of Fasn, elongases and desaturases via Srebf-1c in liver from rats. Gene expression of encoding enzymes for fatty acid synthesis and fatty acid composition was evaluated in liver from rats in fasting and feeding (at 30, 60, 90 and 120 min after feeding) when food intake (adequate or high-lipid diet) was synchronized to a restricted period of 7h. Fasn, Scd and Fads2 were induced during 120 min after initial feeding in both dietary groups. This induction may be activated in part by insulin via Srebf-1c. Also, we showed for the first time that Elovl7 may be regulated by insulin and dietary lipids. The failure to synthesize saturated and monounsaturated fatty acids is consistent with a downregulation of Fasn and Scd, respectively, by dietary lipids. A higher content of LC-PUFAs was observed due to a high expression of Elovl2 and Elovl5, although Fads2 was suppressed by dietary lipids. Therefore, elongases may have a mechanism that is Srebf-1c-independent. This study suggests that a high-lipid diet triggers, during 120 min after initial feeding, a tight coordination among de novo lipogenesis, elongation, and desaturation and may not always be regulated by Srebf-1c. Finally, upregulation by feeding (insulin) of Fasn, Scd, Fads2 and Srebf-1c is insufficient to compensate for the inhibitory effect of dietary lipids.     

On the origin of pristane in marine organisms

Phytol-U-(14)C was adsorbed on algae and ingested in this form by zooplanktonic copepods (two species of Calanus). The lipids of these animals were analyzed after 48 hr and found to contain radioactive pristane and radioactive phytanic acid. The conversion of phytol to pristane by the copepods is interpreted as a likely biological source of pristane in nature.     

Seasonal occurrence of yeasts and yeast-like organisms in the river Danube

One hundred and seventy yeast strains belonging to 14 genera and 29 species were isolated from 112 water samples of the river Danube in the area of Bratislava. The samples were collected through the year from April to March.Saccharomyces cerevisiae, Candida maltosa, Aureobasidium pullulans, Cystofilobasidium capitatum, Rhodotorula glutinis, Geotrichum candidum, and Candida krusei were the most frequent. The basidiomycetous yeasts and yeast-like organisms with oxidative metabolism were present in approximately equal numbers to those with fermentative metabolism. Saccharomyces cerevisiae was the dominant yeast and was isolated from 50% of all samples examined and represented approximately one quarter of the yeast community.Yeast densities ranged from 100 to 21,100 CFU per litre. The highest population density was observed in October. Cryptococcus albidus, Saccharomyces cerevisiae, Rhodotorula glutinis, and Aureobasidium pullulans formed the main part of the yeast population in this month.     

Cryopreservation of the cells and larvae of marine organisms

This paper reviews original and literature data on the cryoresistance of the cells of marine organisms. The technology for the cryopreservation of these objects includes the selection of freezing conditions and the use, in addition to traditional cryoprotectants, of combinations of exogenous lipids, antioxidants, and disaccharide trehalose as a membrane stabilizing agent. We propose an approach for the preservation of marine invertebrate cells. The approach is based on the use of biologically active substances obtained from the tissues of marine organisms. Our results demonstrated the synergistic activity of these components of cryoprotective mixtures, and, at the same time, the specificity of antioxidant effects. An analysis of the factors that determine the choice of cryoprotectors was performed for various cell types. The development of the cryopreservation methods of marine organisms provides an opportunity for their wide application in both developmental biology and in marine biotechnology and serves as an important prerequisite for the cryobank creation.     

The formation and occurrence of polynuclear aromatic hydrocarbons associated with food

Polynuclear aromatic hydrocarbons are common contaminants of processed food, usually at trace levels. These hydrocarbons are products of combustion and pyrolysis, and are present in petroleum and coal, and in products derived from them. Most polynuclear aromatic hydrocarbons are not carcinogenic, but some of them are, and a few are potent inducers of skin and lung tumors in mice. Their carcinogenic properties have not been fully explored, but they seem to be less potent by ingestion or inhalation, and they are known as a group to produce cancer in humans. The most effective carcinogens among them are those with 5 or 6 fused rings, and these tend to be less prevalent in mixtures than the 3- and 4-ring hydrocarbons, most of which are not carcinogenic. Sophisticated analytical methods, using solvent extraction and chromatography have been developed to detect and measure polynuclear aromatic hydrocarbons at levels of 1 in 10(9) (1 part per billion) or less, and these have been applied to the measurement of individual compounds in foods, as well as in products of combustion and pyrolysis. Wood smoke and smoked foods contain the carcinogenic benzo[a]pyrene at levels of 1 ppb, and other hydrocarbons; liquid smoke has lower levels. Crude vegetable oils have higher concentrations, but purified 'deodorized' oils have benzo[a]pyrene levels near 1 ppb. Sausages cooked over burning logs had as much as 200 ppb benzo[a]pyrene. Charcoal-broiled steaks and ground meat had benzo[a]pyrene concentrations up to 50 micrograms/kg, while less fatty pork and chicken had lower concentrations (up to 10 micrograms/kg). It was probable that the rendered fat dripped on to the hot charcoal and pyrolyzed to form quantities of polynuclear aromatic hydrocarbons, which rose with the smoke to deposit on the meat. Therefore, oven cooking or cooking with a heat source above the meat, or segregation of the meat from the smoke resulted in food containing negligible amounts of polynuclear aromatic hydrocarbons. Modifications of cookings practices accordingly would greatly reduce exposure to this group of carcinogens.     

Molecular genetics and the management and conservation of marine organisms

Biochemical and molecular species identification techniques have a broad range of applications in the management and conservation of marine organisms. While species boundaries are not always clearly defined, phylogeneticists utilise autapomorphic characters to distinguish phylogenetic species. Genetic markers discriminate between marine taxa when traditional morphological distinctions are unclear. The applications of these techniques can be divided into four general categories. Firstly, compliance enforcement, which often depends on genetic identification techniques to enable officials to identify the species to which regulations pertain. Secondly, quality control applications, to allow for the testing of marine products to guard against fraudulent substitution with less valuable species, which is particularly pertinent since processing often obliterates identifiable features. Thirdly, a variety of applications to ecological and life-history studies and conservation management are reported. Here, the genetic identification techniques of species from cryptic life-cycle stages or of morphologically indistinct species are an indispensable tool for marine scientists, conservators and managers. Lastly, the application of genetic techniques for sourcing population origin is briefly discussed. The biochemical and molecular techniques applied to species identification all exploit phenotypic or genotypic polymorphisms that are sampled using either tertiary level protein based methods or primary level DNA based methods. In this review, examples of the applications along with the total protein, allozyme, serological, PCR and other DNA based methodologies are briefly described and some generalities with regard to their use are presented.     

The distribution,abundance and seasonality of pelagic marine invertebrate larvae in the maritime Antarctic

A survey of pelagic larvae was undertaken between November 1992 and February 1995 at Signy Island, Antarctica (60° 43 minutes S, 45° 36 minutes W). A diver-towed net and hand-held plankton pump were used at five sites of varying depths (6 to 30 m) and benthic substrata, in a combination of monthly and fortnightly samples. Overall larval ecological diversity was much higher than expected, with 131 morphologically distinct larval forms collected, apparently representing most of the benthic phyla present. The species richness observed is comparable with levels recorded at temperate latitudes, and higher than Arctic data and the implications for Thorson''s rule (the inferred cline of reduced pelagic larval diversity towards high latitudes) is discussed. Larval abundances were low (mean 2.6 individuals per cubic metre) which were two to six orders of magnitude lower than peaks in comparable data from temperate and tropical zones. We suggest that the low abundances recorded are a reflection of both slow developmental rates and a high dilution of larvae, reducing synchrony and spreading larvae over larger distances. Three seasonal periods, during which different larval types occur, have been identified. Summer, late summer and winter spawning strategies were discernable, and in some groups larvae occurred throughout the year.     

Relationship between the occurrence of cysteine in proteins and the complexity of organisms

The occurrence and relative positions of cysteine residues were investigated in proteins of various species. Considering random mathematical occurrence for an amino acid coded by two codons (3. 28%), cysteine is underrepresented in all organisms investigated. Representation of cysteine appears to correlate positively with the complexity of the organism, ranging between 2.26% in mammals and 0. 5% in some members of the Archeabacteria order. This observation, together with the results obtained from comparison of cysteine content of various ribosomal proteins, indicates that evolution takes advantage of increased use of cysteine residues. In all organisms studied except plants, two cysteines are frequently found two amino acid residues apart (C-(X)(2)-C motif). Such a motif is known to be present in a variety of metal-binding proteins and oxidoreductases. Remarkably, more than 21% of all of cysteines were found within the C-(X)(2)-C motifs in ARCHEA.: This observation may indicate that cysteine appeared in ancient metal-binding proteins first and was introduced into other proteins later.