Combined action of nicotinamide and adenine in preservation of packed red cells

An alkaline resuspension solution "Erythronaph" with adenine and nicotinamide has been developed. It allows to preserve red blood cells for 35 days. Removing leukocytes and platelets up to 90% by brief warning of 24-hour blood prior to centrifugation combined with return of 10% of plasma provide further prolongation of storage of red blood cells in "Erythronaph".     

Bis(adenosyl-5′)tetraphosphate as a partial agonist of ATP receptors in rat sensory neurons

The effects of bis(adenosyl-5)oligophosphates on cation conductance-promoting ATP receptors at the somatic membrane of rat sensory ganglia neurons were investigated. Both bis(adenosyl-5)tetraphosphate and bis(adenosyl-5)pentaphosphate act as partial agonists of ATP receptors at saturating concentration and activate ionic currents of almost one order of magnitude below the amplitude of peak ATP-activated currents. Combined application of these two substances to the neuron produces a considerable decline in the amplitude of ATP-activated ionic currents, competing with ATP for common binding sites.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 4, pp. 427–431, July–August, 1988.     

Chinese hamster cells mutant at the hypoxanthine-guanine phosphoribosyltransferase (GPRT) locus. V. Complementation analysis of ts mutants

Four temperature-sensitive HPRT clones were used for hybridological analysis, which led to increase in complementation rate about 5 times. The probability of complementation, in respect of the HPRT locus proved to be rather high: 14 of 45 hybridization-tested mutants had complementation ability (including 3 ts mutants). Analysis of the complementation rate among mutants revealed clear-cut dependence on the selection conditions: clones grown in a medium with 8-azaguanine showed most frequent complementation. The use of mutants with a new phenotype in hybridization analysis revealed four additional complementation groups, three of which are made of temperature-sensitive clones. Biochemical analysis revealed the presence of hybrid forms of the HPRT enzyme in all hybrids tested. This confirms the intragenic character of complementation. At present, the functional map of the HPRT locus is represented by 9 groups, including a group of mutants with no complementation ability.     

Changes in the activity of antioxidizing enzymes during spermatogenesis

A study was made of variation in the activity of the antioxidant defense system enzymes superoxide dismitase (SOD), glutathione peroxidase, (GP) and glutathione-S-transferase (GT) in the cells of mouse spermatogenic epithelium. The cells were fractionated in the gradient of human serum albumin using the STAPUT system. SOD activity was comparable to that in liver cells, that of GP was one order to magnitude lower, and that of GT one order of magnitude higher than in the liver. Differentiation of spermatogenic cells demonstrated phase variations in the activity of these enzymes, with a maximum seen at the stage of late pachytene spermatocytes. SOD, GP and GT activities were discovered to be reduced in postmeiotic cells (early spermatid fractions) by 2.8-3.5; 1.9-2.3 and 4.2-5.6 times, respectively. That reduction was followed by activation of the enzymes at the late stages of spermiogenesis.     

Three carnivorous plant species (Drosera spp.) in European Russia: peaceful coexistence?

In spite of the recent improvements in the understanding of carnivorous plants’ biology, some questions have remained unanswered. In this study, the segregation of food niches (i.e. specialization on different categories of prey) for three sympatric carnivorous temperate Drosera species with different shapes of trapping leaves is tested. Potentially available prey was also taken into account, by using artificial traps. Almost all the prey trapped by the three Drosera species and by passive traps belonged to four insect orders: Diptera, Hymenoptera, Coleoptera, Homoptera, as well as Araneae. Diptera specimens were the main prey for all the species. This study demonstrates that arthropods caught by the three temperate sympatric sundew species (D. rotundifolia, D. obovata and D. anglica), belong to the same orders. The proportions of prey from different orders, caught by different sundew species did not differ significantly. The result does not necessarily imply the absence of interspecific competition for prey: arthropods were identified only to order, and competition may have resulted in specialization on prey taxa of lower rank.     

Study of the structure of streptokinase conjugates with a hydrophilic vinylpyrrolidone copolymer

The modification of streptokinase by a synthetic N-vinylpyrrolidone copolymer leads to formation of conjugates varying in structures according to the proportions of the components in the reaction medium. Based on data obtained from spectrophotometry, as well as sedimentation and diffusion analyses, it is shown that in the presence of excess protein in the reaction medium, formation of the main chain takes place via the copolymer associated with several protein globules. Under conditions of excess modifier copolymer, either single-site and/or multiple-site bonding is possible for the protein backbone, depending on the molecular weight of the copolymer. One of the models for the conjugates obtained in this manner has been corroborated by small-angle X-ray scattering data. CD spectral analyses has been performed in order to demonstrate that covalent modification does not alter the secondary structure of streptokinase in the conjugate whereas the tertiary structure undergoes local changes in conformation.