Deletion analysis of the SUP2 gene in Saccharomyces cerevisiae

The sup2 mutations of the yeast Saccharomyces cerevisiae or plasmid-mediated amplification of the wild type SUP2 gene lead to suppression of different types of nonsense mutations. The Sup2 protein includes a C-terminal region homologous to elongation factor EF-1 alpha and an unique N-terminal region. The SUP2 is an essential gene. The functional role of different regions of the SUP2 gene was investigated, by deleting them without disruption of the reading frame. Such constructs were maintained in yeast on episomal or centromeric plasmids. It was shown that the region, homologous to EF-1 alpha is necessary for viability, while the remaining N-terminal part is nonessential. The region of the first 154 amino acids is necessary and sufficient for the suppressor effect, caused by plasmid-mediated amplification of the SUP2 gene.     

Phosphate Homeostasis in Conditions of Phosphate Proficiency and Limitation in the Wild Type and the phoP Mutant of Streptomyces lividans

Phosphate, as a constituent of the high energy molecules, ATP/GTP and polyphosphate, plays a crucial role in most of the metabolic processes of living organisms. Therefore, the adaptation to low Pi availability is a major challenge for bacteria. In Streptomyces, this adaptation is tightly controlled by the two component PhoR/PhoP system. In this study, the free intracellular Pi, ATP, ADP and polyP content of the wild type and the phoP mutant strain of S. lividans TK24 were analyzed at discrete time points throughout growth in Pi replete and limited media. PolyP length and content was shown to be directly related to the Pi content of the growth medium. In Pi repletion, ATP and high molecular weight (HMW) polyP contents were higher in the phoP mutant than in the WT strain. This supports the recently proposed repressive effect of PhoP on oxidative phosphorylation. High oxidative phosphorylation activity might also have a direct or indirect positive impact on HMW polyP synthesis. In Pi sufficiency as in Pi limitation, the degradation of these polymers was shown to be clearly delayed in the phoP mutant, indicating PhoP dependent expression of the enzymes involved in this degradation. The efficient storage of Pi as polyphosphate and/or its inefficient degradation in Pi in the phoP mutant resulted in low levels of free Pi and ATP that are likely to be, at least in part, responsible for the very poor growth of this mutant in Pi limitation. Furthermore, short polyP was shown to be present outside the cell, tightly bound to the mycelium via electrostatic interactions involving divalent cations. Less short polyP was found to be associated with the mycelium of the phoP mutant than with that of the WT strain, indicating that generation and externalization of these short polyP molecules was directly or indirectly dependent on PhoP.     

Biocenotic characteristics of some Yucatan lentic water bodies based on invertebrate remains in sediments

The Yucatan Peninsula is a karstic environment with almost no permanent surface water flows. All freshwater lentic systems here are supported by underground water. We examined sediments, obtained with an Eckman dredge, from 25 different types of water bodies (sinkholes or cenotes, lagoons, and wetlands), to investigate their biocenotic characteristics. All systems showed differences in their zoocenoses, ostracods being the dominant group in most. Cladocera were scarce in the sediments, represented by only eight genera. It can be partially related to the near absence of a littoral zone in cenotes, due to vertical walls, and the lack of submersed vegetation. In spite of their importance, relatively little work has been done on ostracods from this region of the world.     

Comparative estimation of the EGFP effects on the development of embryos obtained by reciprocal crossing of C57BL/6-Tgn(ACTbEGFP)1Osb/J and C57BL/6 mice

The effect of enhanced green fluorescent protein (EGFP) on the in vitro viability of early embryos of C57BL/6-Tgn(ACTbEGFP)1Osb/J mice has been studied. The number of viable ova in hemizygous females (−/egfp) has been shown to decrease. Irrespective of the EGFP level, it has no deleterious effect on the early development of embryos obtained by reciprocal crossing of hemizygous (−/egfp) and wild-type (−/−) mice.     

New data on sexual dimorphism and reproductive biology of Alaska skate <Emphasis Type="Italic">Bathyraja parmifera</Emphasis> from the northwestern Pacific Ocean

New data on sexual dimorphism and features of reproductive biology of Alaska skate Bathyraja parmifera from the western Bering Sea and the northern Sea of Okhotsk are presented. Based on comparative analysis of 11 external morphological characters, the males differ from the females in the length of the disc and snout length (to the eyes, to the mouth, and to the nostrils). In the western Bering Sea, 50% of the females and 50% of the males reach the first sexual maturity at 84.5 cm TL and 85.2–90.2 cm TL, respectively; in the Sea of Okhotsk, 50% of the males reach their first sexual maturity at 80.8–83.8 cm TL (the assessment depends on the features of the method). Among smaller skates (less than 45 cm TL), the males prevail, but the proportion of the females increases in larger size groups; the sex ratio becomes equal in the exemplars 60–80 cm TL, but the males prevail again among the largest fishes (more than 80 cm TL).     

Antiradical and NO-Inhibiting activities of β-hydroxy(ethoxy) derivatives of nitrous heterocycles

The antiradical and NO-inhibiting activities of β-hydroxy(ethoxy) derivatives of nitrous heterocycles (3-hydroxypyridine, 5-hydroxybenzimodazole, and 6-hydroxy(alkoxy)-benzothiazole) have been studied. The antiradical activity has been studied using a homogeneous hydrophilic chemiluminescent system, and the quenching constants (K _i ) have been determined. For the most reactive compound, 4-methylthiobenzimidazolyl-3-hydroxypyridine, K _i = 4.5 × 10⁵ M⁻¹. The NO-inhibiting activity was estimated on a model of the endotoxin shock of experimental animals using a spin trap of nitric oxide radicals based on complexes of iron with sodium diethyldithiocarbamate. It was found that the compounds at doses of 0.25–1 mmol/kg have both the inhibitory and stimulating action on the production of nitric oxide in the liver of animals. The results obtained suggest that some derivatives of nitrous heterocycles can be used as effective antioxidant preparations.     

Experiments with small-size dynamic loads in the S-300 high-power pulsed generator

Results are presented from experimental studies of promising output units for high-current pulsed generators within the framework of the program on inertial confinement fusion research with the use of fast Z-pinches. The experiments were carried out on the S-300 facility (4 MA, 70 ns, 0.15 Ω). Specifically, sharpening systems similar to plasma flow switches but operating in a nanosecond range were investigated. Switching rates to a load as high as 2.5 MA per 2.5 ns, stable switching of a 750-kA current to a low-size Z-pinch, and the radiative temperature of the load cavity wall of up to 50 eV were achieved.     

Cochliopodium barki n. sp. (Rhizopoda, Himatismenida) re-isolated from soil 30 years after its initial description

A strain of Cochliopodium isolated from grassland soil at Sourhope Research Station (Scotland, UK) was found to be identical to the strain “Cochliopodium sp.2” studied by Bark in 1973. We name it Cochliopodium barki. It belongs to a group of species (comprising also C. minus and Cochliopodium sp. “NYS strain”) with very similar scale pattern.     

Differential Participation of Central L-Glutamate Receptors of non-NMDA-Subtype in Associative Learning of the Honeybee Apis mellifera

Participation of non-NMDA-receptors in associative learning in the honeybee was analyzed using a complex approach. There were studied effects of systemic and intracerebral AMPA injections on retention of the elaborated conditional reflex in short-term memory, on dynamics of the bioelectrical activity of neurons of calyx of the mushroom bodies, and on the limb locomotor activity. It has been shown that the systemic and intracerebral AMPA injections stimulate processes of short-term memory and activate bioelectrical activity of neurons of the mushroom body medial calyx. Antagonist of AMPA-receptors NS-257 HCl suppressed spontaneous activity of these neurons. The observed processes did not depend on the character of locomotor activity. These results confirm the hypothesis proposed earlier about involvement of non-NMDA-receptors in the process of associative learning.