Study of non-consumptive mortality of Crustacean zooplankton in a Siberian reservoir using staining for live/dead sorting and sediment traps

We studied non-consumptive (non-predatory) mortality of Daphnia and Cyclops vicinus during four sampling seasons. Mortality estimations were based on live/dead sorting using special staining and measurements of sedimentation rates for dead individuals, depended on wind speed. Original equations were used for calculations. The estimated specific non-consumptive mortality never had biologically senseless negative values, which were often obtained on the basis of the other ways of mortality estimations, and was in a good agreement with other components of population dynamics. As found, the non-consumptive mortality was the important, often the determinant component of the zooplankton population dynamics.     

Changes in the starvation response through covalent cell attachment

Covalent attachment of Candida utilis cells, possibly simulating natural microbial immobilizations, stimulated stable and significant enhancement of extracellular production of alkaline protease, specifically induced by four different starvation conditions. The enzyme analysis confirmed the identity of the proteases released under all conditions of starvation and no parallel production of other proteolytic enzyme. The enhancement phenomenon as a uniform and stable effect of the whole cell immobilization is discussed in relation to the effect of multipoint, cell-solid surface contact, potentially bringing positive modulations of complex, cellular functions.     

Development of seawater adaptation in pink salmon,Oncorhynchus gorbuscha,during downstream migration: relationships to temperature and residual yolk

Synopsis Seawater adaptability of wild pink salmon, Oncorhynchus gorbuscha, alevins was investigated using 96 h LC50 test, muscle sodium level and weight loss tests. Five temperature (2, 6, 9, 13 and 16°C) and two yolk groups were analysed during the beginning, the middle and the end of downstream migration. Both temperature and amount of residual yolk affected seawater adaptability. The computation of muscle sodium levels and weight loss after a short term (3–12 h) seawater challenge test may be a convenient method to estimate the seawater adaptability of fish too small to allow analysis of blood sodium concentration.     

New Potential Cell Wall Glucanases of Saccharomyces cerevisiae and Their Involvement in Mating

Biotinylation of intact Saccharomyces cerevisiae cells with a nonpermeant reagent (Sulfo-NHS-LC-Biotin) allowed the identification of seven cell wall proteins that were released from intact cells by dithiothreitol (DTT). By N-terminal sequencing, three of these proteins were identified as the known proteins β-exoglucanase 1 (Exg1p), β-endoglucanase (Bgl2p), and chitinase (Cts1p). One protein was related to the PIR protein family, whereas the remaining three (Scw3p, Scw4p, and Scw10p [for soluble cell wall proteins]) were found to be related to glucanases. Single knockouts of these three potential glucanases did not result in dramatic phenotypes. The double knockout of SCW4 and the homologous gene SCW10 resulted in slower growth, significantly increased release of proteins from intact cells by DTT, and highly decreased mating efficiency when these two genes were disrupted in both mating types. The synergistic behavior of the disruption of SCW4 and SCW10 was partly antagonized by the disruption of BGL2. The data are discussed in terms of a possible counterplay of transglucosidase and glucosidase activities.     

Adsorption of nucleosides on mercury surface

Summary All nucleosides currently occurring in nucleic acids are, under the given experimental conditions, surface-active substances. If the concentration is sufficiently high, the most of nucleosides in the electrode surface associates and creates a surface film just as the corresponding bases do. Only with uridine, thymidine, and cytidine, unlike the corresponding bases, no associations in the electrode surface occur.     

Transport of groundwater-borne phosphorus to Lake Bysjön,South Sweden

Lake Bysjön is a hypertrophic seepage lake, with groundwater as a main external source of phosphorus. Twelve groundwater samples from the vicinity of the lake were high in phosphate (0.4 to 11 mg l^–1, mean value 2.57 mg l^–1 PO₄-P), both within the riparian zone and in two shallow wells located upstreams the lake in the nearby village. Phosphorus sorption capacity of four sand samples measured with the Langmuir isotherm method was low (7.3 to 121,1 mg kg^–1 PO₄-P), with the lowest values found within the riparian zone. It is suggested that the phosphorus originates from garden fertilizers and other human sources, and that the low absorption capacity of the soils is caused by the leaching of calcium from the watershed, a process which started some 3000 years ago. Riparian zone itself has almost no retention capacity, and processes within it (e.g., redox-related) have only secondary importance for the transport of phosphorus to the lake.     

Genetic re-engineering of polyunsaturated phospholipid profile of Saccharomyces cerevisiae identifies a novel role for Cld1 in mitigating the effects of cardiolipin peroxidation

Cardiolipin (CL) is a unique phospholipid localized almost exclusively within the mitochondrial membranes where it is synthesized. Newly synthesized CL undergoes acyl remodeling to produce CL species enriched with unsaturated acyl groups. Cld1 is the only identified CL-specific phospholipase in yeast and is required to initiate the CL remodeling pathway. In higher eukaryotes, peroxidation of CL, yielding CL_OX, has been implicated in the cellular signaling events that initiate apoptosis. CL_OX can undergo enzymatic hydrolysis, resulting in the release of lipid mediators with signaling properties. Our previous findings suggested that CLD1 expression is upregulated in response to oxidative stress, and that one of the physiological roles of CL remodeling is to remove peroxidized CL. To exploit the powerful yeast model to study functions of CLD1 in CL peroxidation, we expressed the H. brasiliensis Δ¹²-desaturase gene in yeast, which then synthesized poly unsaturated fatty acids(PUFAs) that are incorporated into CL species. Using LC-MS based redox phospholipidomics, we identified and quantified the molecular species of CL and other phospholipids in cld1Δ vs. WT cells. Loss of CLD1 led to a dramatic decrease in chronological lifespan, mitochondrial membrane potential, and respiratory capacity; it also resulted in increased levels of mono-hydroperoxy-CLs, particularly among the highly unsaturated CL species, including tetralinoleoyl-CL. In addition, purified Cld1 exhibited a higher affinity for CL_OX, and treatment of cells with H₂O₂ increased CLD1 expression in the logarithmic growth phase. These data suggest that CLD1 expression is required to mitigate oxidative stress. The findings from this study contribute to our overall understanding of CL remodeling and its role in mitigating oxidative stress.