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PubMedDate not supplied

[Hygienic aspects of water quality from the Danube River in Novi Sad].

In order to assess the water quality of the Danube river during the bathing season (June, 15. -September, 15.) from 1992-1995, water was examined every day (bacteriologically and chemically) while "big chemistry", hybrid analysis and determination of physiologic groups were performed every other week at the locality of the most beautiful beach called Strand in Novi Sad. Analyses showed that water did not meet criteria of the II class quality in regard to microbiologic requirements in 63.44% of samples (n = 372) and in 6.45% of samples in regard to chemical requirements (n = 372). On the basis of zooplankton and phytoplankton distribution, water of the Danube river belongs to the demanded class of betamesosaprobicity (saprobic index after Pantle-Buck 1.9-2.33). According to Kohl categorization, water belongs to the II and III class. Analyses of the nonspecific bacteriophage point to the most common occurrence of bacteriophage for Shigella sonnei. Salmonella paratyphi B and Shigella flexneri 2-a, which points to earlier fecal contamination. In regard to physiologic groups, water contained heterogenic organic materials. On the basis of occurrence of oligotrophs and heterotrophs, the process of self-purification is mostly satisfactory. The most important causes of chemical contamination were as follows: supersaturation and saturation, decreased oxygen concentration, increased use of BPK5, as well as increased concentrations of iron, barium, arsenic, total dissolving phenols, and occasionally strontium and chloroform. Remains of organochlorine insecticides used to be found in earlier periods.

Water Microbiology↗
PubMed2002

Light-induced mass turnover in a mono-species community of mixotrophs.

We formulate a simple model for growth of a facultative photoautotroph with chemoheterotrophic capabilities. The organism is described by zero, one or three reserve components, and one structural component, all taken to be generalized compounds. The rules of synthesizing units are used for interactions among the uptake processes of the various nutrients and light (parallel processing), and for the merging of autotrophic and heterotrophic activities (sequential processing). For simplicity, we focus on the assimilation of inorganic carbon, inorganic nitrogen and light, and of two organic compounds (dead reserves and dead structure) that originate from aging. The process of resource recycling in a closed environment, as driven by light, and its links with community's structure (amount of biomass) is analysed in this simplest of all communities. Explicit analytical expressions for the steady states show how structure and function depend on the system parameters light, total carbon and total nitrogen. The behaviour resembles the Monod model for the Canonical Community, a three-species ecosystem consisting of producers, consumers and decomposers. If trophic preferences of a mixotroph are allowed to follow a random walk across generations, a trophic structure evolves where mixotrophs coexist with auto- and heterotrophs. Depth profiles are presented for the implied steady-state concentrations of dissolved inorganic carbon and nitrogen.

Aging↗
PubMed2001

An overview of endosymbiotic models for the origins of eukaryotes, their ATP-producing organelles (mitochondria and hydrogenosomes), and their heterotrophic lifestyle.

The evolutionary processes underlying the differentness of prokaryotic and eukaryotic cells and the origin of the latter's organelles are still poorly understood. For about 100 years, the principle of endosymbiosis has figured into thoughts as to how these processes might have occurred. A number of models that have been discussed in the literature and that are designed to explain this difference are summarized. The evolutionary histories of the enzymes of anaerobic energy metabolism (oxygen-independent ATP synthesis) in the three basic types of heterotrophic eukaryotes those that lack organelles of ATP synthesis, those that possess mitochondria and those that possess hydrogenosomes--play an important role in this issue. Traditional endosymbiotic models generally do not address the origin of the heterotrophic lifestyle and anaerobic energy metabolism in eukaryotes. Rather they take it as a given, a direct inheritance from the host that acquired mitochondria. Traditional models are contrasted to an alternative endosymbiotic model (the hydrogen hypothesis), which addresses the origin of heterotrophy and the origin of compartmentalized energy metabolism in eukaryotes.

Adenosine Triphosphate↗
PubMed2005

What it takes to get a herbicide's mode of action. Physionomics, a classical approach in a new complexion.

Discovering new herbicides with novel modes of action is a priority assignment in plant protection research. However, for active compounds identified in greenhouse screens, the crucial point is to tread the most efficient path in determining a herbicide's target site, regarding chance of success, time and research costs. Today, in the literature, molecular (functional genomics, transcriptomics), biochemical (proteomics) and analytical (metabolomics) approaches are particularly discussed. So far, less attention has been focused on the comprehensive physiological profiling of the complex plant system as a procedure which enables new herbicides, with an unknown target site for their mode of action, to be screened rapidly. Here, the concept of an array of 'functional' bioassays is presented which has ultimately been developed from the classical tool of mode of action diagnosis by symptoms. These bioassays are designed to differentiate between the distinct responses of the multiple organization units (plant, tissue, meristematic cell, organelle), developmental stages, types of metabolism (phototrophic, heterotrophic) and physiological processes in the plant organism. The response pattern to a herbicide can be viewed as the end result of changes induced in the molecular and biochemical process chain and should be diagnostic of its physiological mode of action. The results can be interpreted directly or a fingerprint database for all known modes of action to be screened for analogy. The term 'physionomics' is proposed for this comprehensive physiological profiling of the plant system, following the parallel terminology of the molecular and biochemical 'omics' technologies. Physionomics procedures provide a first clue to the mode of action of a new herbicide that can direct more time-consuming and costly molecular, biochemical, histochemical or analytical studies to identify a target site more efficiently.

Biological Assay↗
PubMed2003

A critical comparison of respirometric biodegradation tests based on OECD 301 and related test methods.

Biodegradation studies of organic compounds in the aquatic environment gain important information for the final fate of chemicals in the environment. A decisive role play tests for ready biodegradability (OECD 301) and in this context, the respirometric test (OECD 301F). Two different respirometric systems (Oxitop and Sapromat) were compared and in two of ten cases (diethylene glycol and 2-ethylhexylacrylate) differences were observed indicating that the test systems are not always equivalent. For 2-ethylhexylacrylate and cyclohexanone we could not state differences in the extent of biodegradation with a municipal and industrial inoculum whereas for cyclohexanone the degradation rate was faster with a municipal inoculum. Allylthiourea (ATU) proved to be an effective inhibitor of nitrification processes and did not affect the heterotrophic biodegradation activity. Modelling of biodegradation processes could be successfully performed with a first-order and a modified logistic plot.

Biodegradation, Environmental↗
PubMed1994

The psaA operon pre-mRNA of the Euglena gracilis chloroplast is processed into photosystem I and II mRNAs that accumulate differentially depending on the conditions of cell growth.

The chloroplast genome of Euglena gracilis contains a psaA operon which encodes a lysine tRNA gene, trnK; psaA and psaB photosystem I genes, and psbE, psbF, psbL and psbJ photosystem II genes. The pre-mRNA of the psaA operon undergoes a complex processing pathway of 5' and 3' tRNA processing, splicing of 11 group II introns and one group II twintron, plus three intercistronic RNA cleavage events. The accumulated transcripts of the psaA operon have been characterized by Northern hybridization, S1 nuclease analysis and primer extension RNA sequencing. The mature 5' end of the psaA-psaB-psbE-psbF-psbL-psbJ hexacistronic transcript lies 8 nt downstream of the trnK gene, and is the result of intercistronic trnK-psaA cleavage. Other intercistronic processing events occur between the psaA and psaB genes and the psaB and psbE genes. Processing at the latter site produces a dicistronic mRNA of PSI genes and a tetracistronic mRNA of PSII genes. The PSI dicistronic transcript is further processed to monocistronic psaA and psaB mRNAs. Secondary structural motifs within the intercistronic regions may be recognition sites for processing. The steady-state levels of psaA operon mRNAs from Euglena grown under several different conditions have been determined. Accumulated transcripts from all growth conditions are spliced, and a proportion are also processed at the intercistronic sites. The products of intercistronic processing increase from heterotrophic dark- to heterotrophic light-grown Euglena, and from heterotrophic light- to photoautotrophic light-grown Euglena. The differential accumulation of psaA operon mRNAs may be a means of chloroplast gene regulation or, alternatively, a consequence of gene expression during chloroplast development.

Animals↗
PubMedDate not supplied

[Glucose consumption and dehydrogenase activity of the cells of the arsenite-oxidizing bacterium Pseudomonas putida].

The rates of glucose assimilation and dehydrogenase activity were studied in Pseudomonas putida oxidizing arsenite. The rate of glucose utilization by the cells decreased in the presence of arsenites in the medium at the beginning because of the microbial adaptation to arsenite. The activity of dehydrogenase fell down when the cells were cultivated in the medium with arsenite. An inverse correlation existed between the rate of glucose assimilation and arsenite oxidation. Apparently, arsenites were oxidized under the action of metabolites produced by P. putida in the process of its heterotrophous growth.

Arsenic↗
PubMedDate not supplied

[The mixotrophy of pathogenic bacteria].

This work deals with materials on the utilization of carbon dioxide and hydrogen from gas-air mixture by Yersinia pseudotuberculosis and Listeria monocytogenes in the process of their cultivation in Hirsch's mineral medium. As follows from the data presented in these materials, the above-mentioned bacterial species are heterotrophic when the infectious process is reproduced in the body of warm-blooded animals and chemolithoautotrophic under the conditions of their life in environmental objects. Such a wide range of their metabolic plasticity ensures the dual character of their saprophytic and parasitic nature.

Biopolymers↗
PubMed1992

Novel long-chain anteiso-alkanes and anteiso-alkanoic acids in Antarctic rocks colonized by living and fossil cryptoendolithic microorganisms.

Saponified extracts of rock samples colonized by cryptoendolithic microbial communities from the McMurdo Dry Valleys of Southern Victoria Land, Antarctica, were separated into hydrocarbon and fatty acid fractions by silica gel column chromatography. Hydrocarbons and methyl esters of fatty acids were analyzed by capillary gas chromatography-mass spectrometry. Unusually, a suite of long-chain anteiso-alkanes (a-C20 to a-C30) and anteiso-alkanoic acids (a-C20 to a-C30) were detected in many samples, together with straight-chain, branched and/or cyclic and acyclic isoprenoid compounds. These novel compounds are probably derived from unidentified heterotrophic bacteria or symbiotic processes in a unique microbial community in the Antarctic cold desert and suggest the occurrence of a special biosynthetic pathway. Long-chain anteiso-alkanes are probably formed through microbial decarboxylation of corresponding anteiso-alkanoic acids. They may serve as new biomarkers in environmental and geochemical studies.

Alkanes↗