The role of arctic zooplankton in biogeochemical cycles: respiration and excretion of ammonia and phosphate during summer

The study of the structural and functional properties of key components of polar marine ecosystems has received increased attention in order to better understand the ecological consequences of future sea temperature rise and seasonal ice retraction. Owing to this purpose, during the ATOS-Arctic cruise, held in July 2007 in the framework of the 2007–2008 International Polar Year, we studied the respiratory carbon demand of mesozooplankton as well as their contribution to the regeneration of inorganic nitrogen and phosphorus (NH₄-N and PO₄-P) via excretion. The studied area comprised several stations along a latitudinal gradient in the East Greenland current, plus a network of stations NW of the Svalbard islands. The specific respiratory carbon losses and phosphorus (PO₄-P) excretion rates were similar or slightly higher than some reports for Arctic mesozooplankton, but the nitrogen (NH₄-N) excretion rates were higher by a factor of 3 when compared with previous data sets. The mesozooplankton respiratory losses were equivalent to 23% of primary production, and at turn zooplankton contributed by excretion to more than 50% of the N and P required by phytoplankton. Although C:N, C:P and N:P metabolic atomic quotients almost coincided with the average Redfield’s stoichiometric ratios, the low C:N values when compared to previous reports suggested a predominance of protein-related metabolic substrates. The potential consequences of changes observed in the C:N, N:P and C:P metabolic ratios of mesozooplankton for Arctic marine ecosystems are discussed.     

Using the methods of statistical analysis to determine the safe content of oil products in gray forest soil

This paper presents an algorithm for determining the content of oil products in remediated soil that is safe for plants and microorganisms. The algorithm includes laboratory modeling of the remediation of soil samples that contain different amounts of soil products, determination of the biological parameters that provide the integral characterization of the soil state in these samples, and analysis of the results on the basis of odds-ratio statistics, which allows one to determine the content of oil products, starting from which the state of an oil-contaminated soil has no significant difference from a control soil.     

Inhibition of cell wall synthesis and acylation of the penicillin binding proteins during prolonged exposure of growing Streptococcus pneumoniae to benzylpenicillin

Growing cultures of an autolysis-defective pneumococcal mutant were exposed to [3H]benzylpenicillin at various multiples of the minimal inhibitory concentration and incubated until the growth of the cultures was halted. During the process of growth inhibition, we determined the rates and degree of acylation of the five penicillin-binding proteins (PBPs) and the rates of peptidoglycan incorporation, protein synthesis, and turbidity increase. The time required for the onset of the inhibitory effects of benzylpenicillin was inversely related to the concentration of the antibiotic, and inhibition of peptidoglycan incorporation always preceded inhibition of protein synthesis and growth. When cultures first started to show the onset of growth inhibition, the same characteristic fraction of each PBP was in the acylated form in all cases, irrespective of the antibiotic concentration. Apparently, saturation of one or more PBPs with the antibiotic beyond these threshold levels is needed to bring about interference with normal peptidoglycan production and cellular growth. Although it was not possible to correlate the inhibition of cell wall synthesis or cell growth with the degree of acylation (percentage saturation) of any single PBP, there was a correlation between the amount of peptidoglycan synthesized and the actual amount of PBP 2b that was not acylated. In cultures exposed to benzylpenicillin concentrations greater than eight times the minimal inhibitory concentration, the rates of peptidoglycan incorporation underwent a rapid decline when bacterial growth stopped. However, in cultures exposed to lower concentrations of benzylpenicillin (one to six times the minimal inhibitory concentration) peptidoglycan synthesis continued at constant rate for prolonged periods, after the turbidity had ceased to increase. We conclude that inhibition of bacterial growth does not require a complete inhibition or even a major decline in the rate of peptidoglycan incorporation. Rather, inhibition of growth must be caused by an as yet undefined process that stops cell division when the rate of incorporation of peptidoglycan (or synthesis of protein) falls below a critical value.     

Two-dimensional gel analysis of swine histocompatibility antigens

Miniature swine MHC antigens from three inbred herds were examined by two-dimensional gel electrophoresis. These antigens were found to constitute a series of complex glycoproteins displaying haplotype-specific patterns that allowed the distinction of both class I and class II molecules among the three haplotypes. Selected outbred pig antisera reacted with a subset of class I antigens, suggesting the presence of at least two distinct molecular species among these antigens. Similarly, alloantisera reacting with mouse Ia antigens and a monoclonal anti-human DR were shown to immunoprecipitate a subset of class II molecules. Examination of the cells from two recombinant haplotypes demonstrated that both independent recombinational events took place between the class I and class II genes.     

Islet cell and 64K autoantibodies are associated with plasma IgG in newly diagnosed insulin-dependent diabetic children

There is a high prevalence of islet cell antibodies (ICA) and autoantibodies detected against an islet cell protein of Mr 64,000 at the time of clinical diagnosis of insulin-dependent diabetes (IDDM). In view of the biphasic immune response after antigen presentation, the purpose of this study was to determine the presence of ICA and antibodies against the 64,000 islet antigen after separation of IgM from IgG to prevent interference between the two antibody classes. Plasma samples from 10 newly diagnosed IDDM children and 10 healthy controls were precipitated with polyethylene glycol (PEG), and the crude Ig was subjected to Sephacryl S-300 chromatography to separate IgM and IgG. ICA determined by indirect immunofluorescence on frozen sections of human pancreas showed reduced background immunofluorescence intensity in the purified fractions compared with crude plasma. The number of ICA-positive samples among the IDDM patients increased from 7/10 in plasma to 9/10 in the IgG fraction. There was an increase in the ICA titer in 6/9 of the positive samples. All purified IgM samples were ICA negative. Immunoprecipitation experiments by using Nonidet P-40 detergent lysates of [35S]methionine-labeled neonatal rat islets demonstrated that the 64,000 autoantibodies were in the IgG fraction. We found 7/10 IDDM samples to be positive, whereas all controls were negative. The background in the autoradiographic analysis was markedly reduced in the IgG fractions compared with immunoprecipitates with crude or PEG-purified plasma and the IgM fraction. ICA titers did not correlate to the ability of the IgG fraction to precipitate the 64,000 autoantigen. It is concluded that both the ICA and 64,000 autoantibodies are primarily of the IgG class at the time of clinical onset of IDDM, and that purification of IgG from human IDDM plasma facilitates the detection of the rat islet cell 64,000 antigen.     

Glycerol models of the ciliated epithelium of bronchial mucosa and their use in the diagnosis of chronic nonspecific lung diseases

The method of extraction of ciliated epithelium from biopsy samples of human bronchial mucosa with glycerol is suggested. Permeabilized cilia of glycerol-extracted cells can be easily reactivated by exogenous ATP. This method was used for the study of ciliary dyskinesia in patients with chronic lung diseases. It was shown that in patients with Kartagener's syndrome neither freshly-isolated, nor glycerol-extracted ATP-treated cilia were motile. On the other hand, in some patients with bronchial asthma ATP reactivated glycerol-extracted cilia, while cilia of freshly-isolated cells remained immotile. The study shows that glycerol permeabilization and reactivation by ATP can be used for the analysis of cilial contractile apparatus in patients with chronic lung disease.     

Skipper impoverishment on large West Mediterranean islands (Lepidoptera Hesperioidea): deterministic,historical and stochastic factors

Biogeographical analyses are applied to skipper (Hesperioidea) presence/absence data from the Western Mediterranean mainland and the three largest islands (Sardinia, Corsica and Sicily) in order to identify potential conservation issues. The analyses performed on species, both collectively and individually, indicate that regional species richness and occurrence in the Mediterranean zone are largely predicted by latitude and area but that islands have impoverished faunas. Several species, predicted to be present on these islands from logistic regression of their continental distributions, are actually absent. The number of species predicted to be present from logistic regression analyses for each island, closely matched the number of species predicted to occur in regional-focused multiple regression analysis. This suggests that missing species have been identified. When compared with species that occur in Sicily and Corsica, the missing species are shown to differ for ecological traits, mainly those linked to altitudinal tolerance. No ecological distinctions were disclosed for Sardinian skippers suggesting a mainly stochastic colonisation. These results, and those from an analogous study carried out on Papilionoidea, point to Hesperioidea having (i) overall more impoverished faunas on islands and (ii) being subject to stochastic or historical colonisation events more than Papilionoidea. Species not predicted to occur on islands based on their mainland distributions and ecological traits, are foci for conservation attention. However, as many species becoming extinct on the islands may be irreplaceable, all species, in particular the Sardinian ones, deserve to be conserved.     

Glycosylation of catalase inhibitor necessary for activity

A protein isolated from maize scutella which inhibits catalase in vitro has been shown to contain 12% carbohydrate in the form of galactose. This corresponds to four galactose molecules per inhibitor subunit. Removal of the carbohydrate with β-galactosidase or blockage with a galactose-specific lectin abolished activity of the inhibitor.