Redox heterogeneity of subsurface waters in the Mesoproterozoic ocean

A substantial body of evidence suggests that subsurface water masses in mid‐Proterozoic marine basins were commonly anoxic, either euxinic (sulfidic) or ferruginous (free ferrous iron). To further document redox variations during this interval, a multiproxy geochemical and paleobiological investigation was conducted on the approximately 1000‐m‐thick Mesoproterozoic (Lower Riphean) Arlan Member of the Kaltasy Formation, central Russia. Iron speciation geochemistry, supported by organic geochemistry, redox‐sensitive trace element abundances, and pyrite sulfur isotope values, indicates that basinal calcareous shales of the Arlan Member were deposited beneath an oxygenated water column, and consistent with this interpretation, eukaryotic microfossils are abundant in basinal facies. The Rhenium–Osmium (Re–Os) systematics of the Arlan shales yield depositional ages of 1414 ± 40 and 1427 ± 43 Ma for two horizons near the base of the succession, consistent with previously proposed correlations. The presence of free oxygen in a basinal environment adds an important end member to Proterozoic redox heterogeneity, requiring an explanation in light of previous data from time‐equivalent basins. Very low total organic carbon contents in the Arlan Member are perhaps the key—oxic deep waters are more likely (under any level of atmospheric O₂) in oligotrophic systems with low export production. Documentation of a full range of redox heterogeneity in subsurface waters and the existence of local redox controls indicate that no single stratigraphic section or basin can adequately capture both the mean redox profile of Proterozoic oceans and its variance at any given point in time.     

Global comparison of bicosoecid Cafeteria-like flagellates from the deep ocean and surface waters,with reorganization of the family Cafeteriaceae

Cafeteria is one of the most common and ecologically significant genera of heterotrophic nanoflagellates in marine plankton. We could isolate and cultivate 29 strains morphologically similar to Cafeteria obtained from surface waters and the deep sea all over the world’s ocean. Morphological characterization obtained by high resolution microscopy revealed only small differences between the strains. Sequencing the type material of the type species C. roenbergensis (CCAP 1900/1) and molecular analyses (18S rDNA, 28S rDNA) of newly isolated strains resulted in a revision and separation of the Cafeteriaceae into two known species (C. roenbergensis, C. mylnikovii) and six new species (C. maldiviensis, C. biegae, C. loberiensis, C. chilensis, C. graefeae, C. burkhardae). Many deposited Cafeteria sequences at GenBank and most of our own sequences clustered within one clade (C. burkhardae) with a p-distance of 5% to strain CCAP 1900/1. Only C. maldiviensis clustered together with the type species C. roenbergensis. While C. burkhardae seems to have a cosmopolitan distribution, the distribution of the other species seems to be more restricted. A strain from the Angola Basin had a p-distance of 10% to Cafeteria species and clustered separately within the Anoecales requiring the erection of a new genus, Bilabrum gen. nov., with B. latius sp. nov. as type species.     

Leishmania donovani: effect of temperature on RNA metabolism

The present study concerns RNA metabolism of Leishmania donovani and its changes during exposure to higher temperatures. The incorporation of labeled precursors into RNA was found to be greatly decreased during incubation at 37 °C in comparison with that at the optimum temperature of growth (22 °C). The decreased incorporation was shown to be mainly due to augmented template RNA degradation. The RNA-polymerase activity remained unaffected at the elevated temperature, but the uptake of labeled uracil was markedly inhibited.     

The effect of temperature on the survival of microorganisms in a deep space vacuum

A Space Molecular Sink Research Facility (Molsink) was used to evaluate the ability of microorganisms to survive the vacuum of outer space. this facility could be programmed to simulate flight spacecraft vacuum environments at pressures in the 10^–10 torr range and thermal gradients (30 to 60°C) closely associated to surface temperatures of inflight spacecraft.Initial populations ofStaphylococcus epidermidis and aMicrococcus sp. were reduced approximately 1 log while exposed to –105 and 34°C, and approximately 2 logs while exposed to 59°C for 14 days in the vacuum environment.Spores ofBacillus subtilis var.niger were less affected by the environment. Initial spore populations were reduced 0.2, 0.3, and 0.8 log during the 14-day vacuum exposure at –124, 34, and 59°C, respectively.This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract No. NAS 7-100, sponsored by the National Aeronautics and Space Administration.     

The effect of temperature on routine metabolism in Tilapia rendalli boulenger

Using a continuous flow respirometer it was shown that young Tilapia rendalli had three distinct phases of oxygen consumption over the temperature range of 17–40° C. In the first phase (17–28° C) the metabolic energy demand followed the normal logarithmic increase with increasing temperature. Between 28 and 37° C the increased oxygen uptake was suppressed and showed a relatively small increase with increasing temperature. This feature was believed to be a significant energy saving function important to the growth of these fish which feed in the warm eulitoral margins of lakes during the day. The final phase shows a return to the original logarithmic increase in oxygen consumption. These results were related to, and compared with, actual changes in biomass at various temperatures and the theoretical and actual biomass changes were found to compare favourably.     

The effect of osmotic pressure on the mobility and metabolism of human spermatozoa]

When human sperm was suspended in a hypertonic medium, their motility is damaged and their oxygen consumption is reduced. Hypotonic conditions are more disastrous because the cells become immotile. These results are discussed with reference to high osmolarity of seminal fluid.     

Experimental effect of lysozyme on macrophage metabolism and resistance to infection

The peritoneal macrophages of mice treated with lysozyme were studied by cytochemical assay. In single and repeated doses of 0.5-5 mg/kg lysozyme induced an increase in macrophage metabolism. This was evident from an increased activity of succinate dehydrogenase, NADP X N-DH and the enzymes catalyzing glycolysis typical of these cells (lactate dehydrogenase and alpha-glycerophosphate). The changes in the activity of the enzymatic systems were most pronounced in minute and less mature macrophages after repeated administrations of the drugs. In a dose of 50 mg/kg lysozyme somewhat decreased the activity of a number of the enzymes. In the doses optimal for the macrophage activity lysozyme had a low effect on the infection resistance and slightly increased the cephotaxim efficiency in experimental staphylococcal infection. This may be mainly due to the immunomodulating effect of lysozyme and its low effect on the large macrophages having the bactericidal effect.     

New and historical records of the ocean sunfish Mola mola in Icelandic waters

The ocean sunfish Mola mola is considered to be globally distributed in both temperate and tropical waters, but there are many gaps in the knowledge of this species' distribution. A total of 31 records of M. mola from Icelandic waters, dating from 1845 to 2014, are presented and georeferenced. An increase in the number of records at the beginning of this century and particularly in 2012, is suggested to be a consequence of both an increase in ocean temperature on the Icelandic shelf and changes in large scale temperature variations in the North Atlantic Ocean.     

Ecological structuring of bacterial and archaeal taxa in surface ocean waters

The Global Ocean Sampling (GOS) expedition is currently the largest and geographically most comprehensive metagenomic dataset, including samples from the Atlantic, Pacific, and Indian Oceans. This study makes use of the wide range of environmental conditions and habitats encompassed within the GOS sites in order to investigate the ecological structuring of bacterial and archaeal taxon ranks. Community structures based on taxonomically classified 16S ribosomal RNA (rRNA) gene fragments at phylum, class, order, family, and genus rank levels were examined using multivariate statistical analysis, and the results were inspected in the context of oceanographic environmental variables and structured habitat classifications. At all taxon rank levels, community structures of neritic, oceanic, estuarine biomes, as well as other exotic biomes (salt marsh, lake, mangrove), were readily distinguishable from each other. A strong structuring of the communities with chlorophyll a concentration and a weaker yet significant structuring with temperature and salinity were observed. Furthermore, there were significant correlations between community structures and habitat classification. These results were used for further investigation of one-to-one relationships between taxa and environment and provided indications for ecological preferences shaped by primary production for both cultured and uncultured bacterial and archaeal clades.     

Experimental effect of bruneomycin on the energy metabolism of liver tissue]

The effect of an antitumor antibiotic bruneomycin on the energy metabolism in the liver tissue was studied. Four hours after the drug administration the consumption of glycogen and glucose in the liver tissue increased because of glycogenolysis activation, which was evident from increased activity of prosphorylase, phosphofructokinase, hexokinase and summation glycolytic activity. 24 and 48 hours after the antibiotic administration the balance of consumption and resynthesis of phosphate macroergs in the liver tissue impaired, which was evident from decreased levels of ATP, impairement of conjugation of the processes of oxidation due to impairement of permeability and structural integrity of the mitochondrial membranes. Further decrease in the glycogen liver levels was mainly due to suppressed resynthesis of glycogen because of destructive-necrotic processes. Simultaneously the processes of glycolytic splitting of glucose decreased which was evident from decreased activity of the enzymes and summation glycolytic activity.     

An evaluation of the metabolism of sestonic and epilithic communities in running waters using an improved chamber technique

SUMMARY. 1. A chamber technique is described which allows the uptake of nutrients in a lotic system to be assessed during a brief experimental period. Sensitive radioisotope techniques were used to determine the metabolism of the planktonic and epilithic communities simultaneously in a pristine boreal forest stream in N.E. Quebec, Canada.
2. Abiotic adsorption of bicarbonate, glucose, methylammonium and phosphate was unimportant in the riffle investigated. Among the biological components, the epilithon was responsible for more than 87% of the uptake of bicarbonate, glucose and methylammonium.
3. The uptake of orthophosphate was predominantly (80%) by organisms in the overlying water. Phosphorus, the nutrient most limiting the system, may be conserved by the epilithon through internal cycling. Uptake rates are within the range reported for other oligotrophic systems.     

A re-interpretation of the effect of temperature on the metabolism of certain marine invertebrates

Measurements by nieans of an oxygen electrode of the rate of oxygen consumption of a wide variety of common intertidal invertebrates show that at least two rates of uptake can be distinguished in the intact animal. First, there is a rapid rate of oxygen uptake corresponding with activity and second there is a slower rate which corresponds with periods of quiescence and which alternates with the fast rate. Intermediate rates correspond with intermediate rates of overt activity. The maximal and minimal rates of oxygen uptake are affected differently by temperature change. The fast rate corresponding to activity ("active metabolism") increases with temperature in approximate agreement with Arrhenius's law. The slow rate corresponding to quiescence ("maintenance metabolism") does not vary with temperature over much of the range 7 to 22.5°C. It is concluded that, contrary to common belief, the intertidal invertebrates studied have a "basal metabolic rate" with a Q₁₀ of approximately one over much of the normal environmental temperature range and in this respect are well suited to life in a habitat where rapid fluctuations in temperature occur.     

A re-interpretation of the effect of temperature on the metabolism of certain marine invertebrates

Measurements by nieans of an oxygen electrode of the rate of oxygen consumption of a wide variety of common intertidal invertebrates show that at least two rates of uptake can be distinguished in the intact animal. First, there is a rapid rate of oxygen uptake corresponding with activity and second there is a slower rate which corresponds with periods of quiescence and which alternates with the fast rate. Intermediate rates correspond with intermediate rates of overt activity. The maximal and minimal rates of oxygen uptake are affected differently by temperature change. The fast rate corresponding to activity ("active metabolism") increases with temperature in approximate agreement with Arrhenius's law. The slow rate corresponding to quiescence ("maintenance metabolism") does not vary with temperature over much of the range 7 to 22.5C. It is concluded that, contrary to common belief, the intertidal invertebrates studied have a "basal metabolic rate" with a Q₁₀ of approximately one over much of the normal environmental temperature range and in this respect are well suited to life in a habitat where rapid fluctuations in temperature occur.     

Global abundance of planktonic heterotrophic protists in the deep ocean

The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml⁻¹ in mesopelagic waters down to 11±1 cells ml⁻¹ in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml⁻¹. The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean''s microbial food web.