Carbon isotopic composition in suspended organic matter and bottom sediments of the East Arctic seas

The samples of water and bottom sediments of the East Siberian and Chukchi Seas collected during the second Russian-American RUSALCA expedition were used to analyze patterns of the isotopic composition of carbon in the organic matter (OM) of suspended material (SOM) and bottom sediments (BOM). Similar to other marine environments, the SOM isotopic composition depended on the ratio between the terrigenous and planktonic OM, both in the water body as a whole and in its parts. Thus, in the East Siberian Sea the carbon of SOM was poorer in ¹³C (??¹³C = ?24.51??) than the open part of the more productive Chukchi Sea (??¹³C = ?22.16??). In the less productive coastal waters of the Chukchi Sea, the ratio of terrigenous OM increased, resulting in a ??¹³C shift to lower values (?23.40??). Due to the influx of reduced products of anaerobic diagenesis of the sediments, elevated total number of microorganisms and dark CO₂ fixation were found in the near-bottom water at the water-sediment biogeochemical barrier. The newly formed biomass of autotrophic microorganisms shifted the carbon isotopic composition of the near-bottom suspended material to more positive ??¹³C values, with the average values of ?23.39 and ?20.37?? for the East Siberian and Chukchi Sea, respectively. Changes in the carbon isotopic composition of OM resulting from microbial activity continued in the upper sediment layers. When the rate of biomass synthesis increased that of biomass consumption, the ¹³C content increased further. At higher rates of OM mineralization, ¹²C accumulated in its remaining part.     

The response of Chironomidae (Diptera) to a long-term exclusion of terrestrial organic matter

We examined the effects of a seven-year detrital exclusion on chironomid assemblages in an Appalachian headwater stream. We hypothesized that litter exclusion would lead to a reduction in all chironomids at both the subfamily and generic levels because organic matter serves as both food and habitat in these headwater streams. Tanytarsini total abundance and biomass significantly declined after litter exclusion. Before litter exclusion, Tanytarsini average abundance was 4271 ± 1135 S.E. m⁻² and 625 ± 98 after litter exclusion. Biomass was 3.57 ± 0.96 mg AFDM m⁻² before litter exclusion and 1.03 ± 0.9 after exclusion. In contrast, Orthocladiinae abundance and biomass did not change because a psammanophilic chironomid, Lopescladius sp., and other Orthocladiinae genera did not decline significantly. Overall chironomid taxa richness and diversity did not change as a result of litter exclusion. However, Canonical Correspondence Analysis (CCA) of genus-level biomass did show a clear separation between the litter exclusion stream and a reference stream. Separation of taxa between the two streams was due to differences in fine (r ² = 0.39) and coarse (r ² = 0.36) organic matter standing stocks and the proportion of small inorganic substrates (r ² = 0.39) present within a sample. As organic matter declined in the litter exclusion stream, overall chironomid biomass declined and the chironomid community assemblage changed. Tanytarsini were replaced by Orthocladiinae in the litter exclusion stream because they were better able to live and feed on biofilm associated with inorganic substrates. Handling editor: K. Martens     

Tracing nitrate sources using the isotopic composition of skeletal-bound organic matter from the calcareous green algae Halimeda

Coral Reefs - The nitrogen (N) isotopic composition (δ15N) of water column nitrate (NO3−) reveals important information about the source(s) of N, and/or the transformation processes...     

Factors affecting composition and thermostability of mengovirus virions.

The composition of mengovirus virions produced by infected cells varies with the incubation temperature. Virons produced at 37.0 or 39.5 degrees contain four major polypeptides (alpha, beta, gamma, and delta) and one minor polypeptide (beta'). Virons produced at 31.5 degrees C contain two additional polypeptides (D1 and E). The virions of two temperature-sensitive (ts) and thermolabile mutants of mengovirus (ts25 and ts88) contain an increased amount of polypeptide beta', with a corresponding decrease in polypeptide beta when compared with the wild-type mengovirus.     

Factors affecting the lytic susceptibility of some marine and terrestrial bacteria

Eighteen gram-negative marine bacteria and two terrestrial species, Escherichia coli and Pseudomonas aeruginosa, were examined for their sensitivity to lysis in distilled water after exposure to a salt solution containing a sea water concentration of Mg2+ (0.05 M) or to 0.5 M NaCl. A spectrum of lytic susceptibility was observed among the marine bacteria ranging from those organisms which lysed in distilled water after exposure to the Mg2+-containing solution, through organisms which could be sensitized to lysis by washing with the NaCl solution, to organisms which failed to lyse in distilled water even after having been washed with a solution of 0.5 M NaCl. Pseudomonas aeruginosa and E. coli fell within this spectrum, the former being capable of being induced to lyse in distilled water by washing with 0.5 M NaCl, while the latter failed to lyse in distilled water after this treatment. It was thus concluded that no overall distinction could be made between marine and terrestrial bacteria on the basis of the sensitivity of the two groups of organisms to lysis in freshwater. Quite large decreases in optical density and increases in the release of ultraviolet-absorbing material took place when cells preexposed to the Mg2+-containing solution or to 0.5 M NaCl were subsequently suspended in distilled water even though in some cases no loss of cell numbers could be detected. In most cases two to three times as much K+ as Na+ and 1/10 to 1/100 as much Mg2+ was required to prevent these changes. For three of the marine bacteria and P. aeruginosa grown in a terrestrial type medium little difference in the requirements for Na+ and K+ to prevent the optical density changes was noted. For P. aeruginosa grown in a marine type medium, cells required more K+ than Na+ to prevent these changes.     

Carbon isotopic composition of Frutexites in subseafloor ultramafic rocks

Micrometer sized stromatolitic structures called Frutexites are features observed in samples from the deep subsurface, and hot-spring environments. These structures are comprised of fine laminations, columnar morphology, and commonly consist of iron oxides, manganese oxides, and/or carbonates. Although a biological origin is commonly invoked, few reports have shown direct evidence of their association with microbial activity. Here, we report for the first time the occurrence of subsurface manganese-dominated Frutexites preserved within carbonate veins in ultramafic rocks. To determine the biogenicity of these putative biosignatures, we analyzed their chemical and isotopic composition using Raman spectroscopy and secondary ion mass spectroscopy (SIMS). These structures were found to contain macromolecular carbon signal and have a depleted ¹³C/¹²C carbon isotopic composition of – 35.4?±?0.50‰ relative to the entombing carbonate matrix. These observations are consistent with a biological origin for the observed Frutexites structures.

     

Factors affecting the glycosphingolipid composition of murine tissues

The effects of genetic strain, sex, age, and pathological state on the distribution and concentration of glycosphingolipids in mouse kidneys and livers were studied. The concentrations of glycosphingolipids and phospholipids in the kidneys and livers of different strains were compared. The major glycosphingolipid in the kidneys of male and female BALB/c, C3H/He, C57/BL, A, and C57xA (F(1) hybrid) mice was a sulfatide, monoglycosyl-(3-sulfate) ceramide; monoglycosyl ceramide was the major component in livers. The kidneys of males of all strains contained significant amounts of diglycosyl ceramide, but those of females contained, at most, only traces. Glycosphingolipid concentration in the male kidneys of C57/BL and C57xA (F(1) hybrid) was much higher than in the female and was also much higher than in the male kidneys of C3H/He, BALB/c, and A strains. The kidneys of "old" (36 wk) male and female C3H/He mice contained much higher proportions of monoglycosyl ceramide than 10-12-wk-old adults. The distributions of glycosphingolipids in kidneys of female C3H/He mice with BP8 ascites tumors and male C57xA (F(1) hybrid) mice with EL4 ascites tumors differed from those in the normal mice. An unknown lipid, present in all glycosphingolipid extracts from kidney and liver, was tentatively identified as cholesterol sulfate.     

Carbon and hydrogen isotopic fractionation during lipid biosynthesis in a higher plant (Cryptomeria japonica)

Compound-specific carbon and hydrogen isotopic compositions of lipid biomolecules (n-alkanes, n-alkanoic acids, n-alkanols, sesquiterpenes, diterpenes, phytol, diterpenols and β-sitosterol), extracted from Cryptomeria japonica leaves, were determined in order to understand isotopic fractionations occurring during lipid biosynthesis in this species. All lipid biomolecules were depleted in both ¹³C and D relative to bulk tissue and ambient water, respectively. n-Alkyl lipids associated with the acetogenic pathway were depleted in ¹³C relative to bulk tissue by 2.4-9.9‰ and depleted in D relative to ambient water by 91-152‰. C₁₅- and C₃₀-isoprenoid lipids (sesquiterpenes, squalene and β-sitosterol) associated with the mevalonic-acid pathway are depleted in ¹³C relative to bulk tissue by 1.7-3.1‰ and depleted in D relative to ambient water by 212-238‰. C₂₀-isoprenoid lipids (phytol and diterpenoids) associated with the non-mevalonic-acid pathway were depleted in ¹³C relative to bulk tissue by 4.6-5.9‰ and depleted in D relative to ambient water by 238-303‰. Phytol was significantly depleted in D by amounts up to 65‰ relative to other C₂₀ isoprenoid lipids. The acetogenic, mevalonic-acid and non-mevalonic-acid pathways were clearly discriminated using a cross-plot between the carbon and hydrogen isotopic fractionations.     

Carbon isotopic record of terrestrial ecosystems spanning the Late Miocene extinction of Oreopithecus bambolii, Baccinello Basin (Tuscany, Italy)

Oreopithecus bambolii is a Late Miocene hominoid with an extensive fossil record in the Baccinello Basin (Tuscany, Italy), and was the only western European hominoid to survive a major extinction event ca. 9.6 Ma (millions of years ago). Oreopithecus lived in the insular Tusco-Sardinian paleobioprovince, where it evolved many unique anatomical specializations that make it important for understanding the mechanisms and history of Late Miocene hominoid evolution. The eventual extinction of Oreopithecus and its associated fauna ca. 6.5 Ma has generally been attributed to interaction with species that arrived from continental Europe following tectonic collision of the Tusco-Sardinian province with mainland Italy, but palynological, paleontological, and sedimentological records indicate an environmental shift toward more variable climate across the extinction event.To explore the possibility of environmental change as a contributing factor in the extinction of Oreopithecus, we developed a stable carbon and oxygen isotope record from organic matter in paleosols from the Baccinello Basin. These data show very low temporal and spatial variability (indicating plant ecosystem stability through time and space) and provide no evidence for ecologically significant changes in floral composition spanning the extinction event, suggesting that environmental change was not an underlying cause for the extinction of Oreopithecus and its associated fauna. The carbon isotope values fall entirely within the range of isotopic variability for modern plants following the C₃ photosynthetic pathway (trees, shrubs, cool-season grasses), indicating that C₄ vegetation (warm-season grasses) was not an important component of biomass. When corrected for temporal variation in the carbon isotopic composition of atmospheric carbon dioxide, the paleosol carbon isotope values are consistent with predicted values based on modern plants and the Baccinello palynoflora, supporting the reliability of paleosol isotopic records as paleoecological proxies.     

Factors affecting the histochemical composition of reinnervated soleus muscle of rat.

The myofibrillar ATPase reaction was utilized to determine the relative proportion of type II fibres in reinnervated soleus muscle 6 months after transection and reunion of the nerve at various distances from the muscle. In self-reinnervated soleus muscle, a highly significant decrease in the percentage of type II fibres from 10.5 +/- 1.6% in normal muscle to 0.7 +/- 0.4% was noted. In randomly reinnervated soleus muscle the percentage of type II fibres gradually increased with the distance of the site of nerve transection from the muscle. After transection and reunion of the muscular branch of the tibial nerve, the type II fibres constituted 34.0 +/- 1.5% and that of the reinnervated soleus muscle after transection and reunion of the sciatic nerve stump was 73.7 +/- 1.7% of the total fibre population. Different factors which might be responsible for the observed differences in the degree of cytochemical transformation of muscle fibre types in the process of reinnervation are discussed.     

Factors affecting the pheromone composition of voided boar saliva

The pheromone binding protein 'pheromaxein' which binds the pheromonal 16-androstene steroids in the saliva of the male pig (boar), was degraded and lost its binding activity in saliva incubated in air for 72 h at 21 degrees C and 37 degrees C. However, pheromaxein and its binding activity were retained in saliva incubated for 168 h at 4 degrees C. When the 3H-labelled pheromones 5 alpha-androst-16-en-3 alpha-ol (3 alpha-androstenol), 5 alpha-androst-16-en-3-one (5 alpha-androstenone) and 5 alpha-androst-16-en-3 beta-ol (3 beta-androstenol) were incubated with boar saliva for 168 h at 21 degrees C, 3 alpha-androstenol was primarily converted to 5 alpha-androstenone and 5 alpha-androstenone to 3 beta-androstenol; 3 beta-androstenol was unchanged. Evidence was obtained for microorganisms being responsible for these steroid transformations.     

Factors affecting the fermentative lactic acid production from renewable resources(1)

Parameters affecting the fermentative lactic acid (LA) production are summarized and discussed: microorganism, carbon- and nitrogen-source, fermentation mode, pH, and temperature. LA production is compared in terms of LA concentration, LA yield and LA productivity. Also by-product formation and LA isomery are discussed.     

陆地生态系统中水溶性有机物动态及其环境学意义

水溶性有机物(DOM)是陆地生态系统中最活跃的有机碳库,也是土壤圈层与相关圈层进行物质与能量交换的重要表现形式,它对重金属、养分元素和有机污染物的活化、迁移与生态毒性有较大影响,在农业土壤溶液中DOM浓度通常在10～80mgC·L^-1,湿地土壤中多数在25～50mgC·L^-1,与森林土壤剖面淋滤水中的DOM相近,但在某些微域土壤环境(如根际和有机肥施用点附近)中DOM浓度可高达200～1000mgC·L^-1,不同来源的DOM在土壤中的迁移性与降解性明显不同,含低分子量组分或亲水性组分较多的DOM不易被土壤吸持而易被微生物降解,pH值相对较高的土壤(如石灰性土壤)对DOM吸附较弱,但pH较低和含有大量氧化物的土壤(如红壤、赤红壤和砖红壤等)则对DOM的吸附较强,施用石灰、土壤淹水或干湿交替、温度升高等有利于土壤保持较高的DOM浓度,由于DOM-金属配合物的形成,DOM能明显促进土壤重金属活化和向下迁移,而且DOM中低分子量或亲水性组分所占比例越低活化作用越强,同样地,由于DOM具有两亲性质,也能明显提高疏水性有机污染物(如农药和持久难降解有机污染物)的水溶性,增加其对环境污染的风险,特别是含疏水性组分越多的DOM这种作用越强．可以认为,继续加强有关DOM在陆地生态系统中产生与消长规律,特别是DOM及其与污染物的配合物从陆地生态系统向水体迁移的机理及其通量的研究,对合理预测污染物的环境行为和科学地进行环境风险评估有重要意义。     

Influence of dissolved organic matter from terrestrial origin on the changes of dinoflagellate species composition in the Gulf of Riga,Baltic Sea

Hydrobiologia - A mesocosm experiment was used to investigate the effect of terrestrial-origin dissolved organic matter (DOM) on the development of dinoflagellates in natural summer phytoplankton...     

Factors affecting party size and composition of chimpanzees (Pan troglodytes verus) Bossou,Guinea

I studied the party sizes of western chimpanzees (Pan troglodytes verus)and factors assumed to affect them at Bossou, Republic of Guinea, West Africa. Party size is negatively correlated with feeding ratio, and larger parties tend to be formed in more dangerous situations (i.e. crossing roads with much traffic). When parties included estrous females, young (i.e., late juvenile and adolescent) males tended to forage with them, independently from their mothers. Lactating females with infants tended to spend more time alone, but the trend was not as apparent as it is in P. t. schweinfurthiat Gombe, Tanzania. These facts suggest that several factors, in addition to food availability, affect party formation, or fission-fusion, of chimpanzees. I also briefly discuss comparatively the pattern of party formation in P. paniscus.     

Carbon isotopic composition of Ambrosia and Artemisia pollen: assessment of a C(3) -plant paleophysiological indicator

? There is limited evidence on how shifts in plant physiological performance influence vegetation variations in the paleorecord. ? To evaluate δ(13) C of pollen from C(3) plants as an indicator of community-level physiology, small quantities (10-30 grains) of untreated pollen and sporopollenin from herbarium specimens of Ambrosia (A.?tomentosa and A.?psilostachya) and Artemisia (A.?frigida, A.?ludoviciana and A.?dracunculus), genera abundant in grassland pollen profiles, were isolated by micromanipulation. Their δ(13) C values were measured using a spooling-wire microcombustion device interfaced with an isotope-ratio mass spectrometer. Leaf δ(13) C was also measured. Carbon isotope discrimination (Δ) for untreated pollen, sporopollenin and leaves was compared with historic records of seasonal precipitation amount, vapor pressure deficit and the Palmer Drought Severity Index (PDSI). ? Each species showed positive correlations between Δ of untreated pollen and sporopollenin. Sporopollenin Δ was most strongly correlated with PDSI. Correlations among leaf Δ and moisture indicators were stronger for Ambrosia than Artemisia. ? These results suggest that sporopollenin Δ indicates the level of moisture stress in C(3) plants. Therefore, δ(13) C analysis of pollen promises to help address important paleoecological questions, such as how community-level physiology contributes to shifts in vegetation composition.     

Factors affecting the removal of organic micropollutants from wastewater in conventional treatment plants (CTP) and membrane bioreactors (MBR)

As a consequence of insufficient removal during treatment of wastewater released from industry and households, different classes of organic micropollutants are nowadays detected in surface and drinking water. Among these micropollutants, bioactive substances, e.g., endocrine disrupting compounds and pharmaceuticals, have been incriminated in negative effects on living organisms in aquatic biotope. Much research was done in the last years on the fate and removal of those compounds from wastewater. An important point it is to understand the role of applied treatment conditions (sludge retention time (SRT), biomass concentration, temperature, pH value, dominant class of micropollutants, etc.) for the efficiency of conventional treatment plants (CTP) and membrane bioreactors (MBR) concerning the removal of micropollutants such as pharmaceuticals, steroid- and xeno-estrogens. Nevertheless, the removal rates differ even from one compound to the other and are related to the physico-chemical characteristics of the xenobiotics.     

The changing role of terrestrial and autochthonous organic matter in newly flooded lakes

Examination of the gut contents of mud-dwelling animals in three newly flooded lakes shows terrestrial organic matter to be a major component, particularly during filling of the lake basin. After filling is complete, a fall-off in total biomass of fauna is usually accompanied by significant reduction in the proportion of terrestrial detritus in favour of algal food. It is concluded that newly formed lakes pass through two phases. During flooding they are dependent on the terrestrial ecosystem. This is followed by a switch, immediately after filling, to more self-sustained autochthonous-based food chains.