Genotypic variation of the response to cadmium toxicity in Pisum sativum L

This work evaluates the (cor-)relations between selected biochemical responses to toxic Cd and the degree of Cd sensitivity in a set of pea genotypes. Ten genotypes were analysed that differ in their growth response to Cd when expressed as root or shoot tolerance indices (TIs). Concentrations of non-protein thiols (NPTs) and malondialdehyde (MDA), activity of chitinase, peroxidase (POX), and catalase significantly increased in all pea genotypes treated with Cd. Cd-sensitivity of genotypes was correlated with relative increases in MDA concentration as well as activities of chitinase and POX, suggesting similar Cd stress effects. Activities of ascorbate peroxidase (APX) decreased, but concentrations of glutathione (GSH) increased in the less Cd-sensitive genotypes. Differences in root and leaf contents of Cd revealed no correlation with TI, metabolic parameters, and enzyme activities in Cd-treated plants, respectively, except that shoot Cd concentration positively correlated with shoot chitinase activity. Toxic Cd levels inhibited uptake of nutrient elements such as P, K, S, Ca, Zn, Mn, and B by plants in an organ- and genotype-specific manner. Cd-sensitivity was significantly correlated with decreased root Zn concentrations. The results show both similarities, as well as distinct features, in Cd toxicity expression in genotypes of one species, suggesting that independent and multi-factorial reactions modulate Cd sensitivity on the low-tolerance level of plants. The study illustrates the biochemical basis of earlier detected genotypic variation in Cd response.     

Evidence for horizontal transfer of 1-aminocyclopropane-1-carboxylate deaminase genes

PCR was used to rapidly identify and isolate 1-aminocyclopropane-1-carboxylate (ACC) deaminase genes from bacteria. The Shimodaira-Hasegawa test was used to assess whether phylogenetically anomalous gene placements suggestive of horizontal gene transfer (HGT) were significantly favored over vertical transmission. The best maximum likelihood (ML) ACC deaminase tree was significantly more likely than four alternative ML trees, suggesting HGT.     

Use of maleic acid by mixed cultures of microorganisms

In a mixed batch culture, Alcaligenes xylosoxidans subsp. xylosoxidans 260 transformed maleic acid into malic acid. Bacillus subtilis 271 used malic acid as a substrate, thus stimulating further transformation of maleic acid. Both bacterial cultures dissociated with the formation of R, S, and M forms. At a concentration of 5.0 g/l, maleic acid was utilized maximally by RS and SS forms of the association A. xylosoxidans and Bacillus subtilis. At concentrations 15.0 and 25.0 g/l, maleic acid was utilized maximally by SS and MS forms of the mixed culture, respectively. Association of bacteria A. xylosoxidans and B. subtilis was not stable under flow conditions water.     

DNA-Protein Complex in Circular DNA from Phage ϕ29

THE DNA of the B. subtilis phage ?29 has been described as unpermuted linear duplex molecules¹ of molecular weight 11 × 10⁶, but the formation of circular molecules has also been indicated, suggesting the existence of cohesive ends^1,2.     

The selection of the composition of the medium for optimizing the amine-synthetic activity of aerobic bacilli]

Nutrient medium chosen as a basic one after preliminary test of several media known from literature has been optimized to intensify biosynthesis and amine nitrogen production by three strains of aerobic sporulating bacteria to culture liquid. The method of mathematical planning used in the experiments has permitted obtaining the components ratio for the medium on which production of amine nitrogen to the environment increased 2.3-3.2 times. The best variants of the optimized medium promoted an increase of the aminosynthetic activity of the studied bacteria by more than 320%. The obtained nutrient medium is appropriate for a wide screening of aerobic bacilli for their ability to synthesize amino compounds.     

Water-soluble and membrane proteins of the central nervous system of the edible snail at different stages of long-term sensitization

An increase in the amount of water-soluble proteins with the mobility of 0.56 in polyacrylamide gel was observed in the snail central nervous system at the early stages of long-term sensitization of the defensive reflex. Such an increase seems to be associated with the enhanced motor activity and a rise in the excitation level at this stage. 2 hours, 1 day and 3 days after long-term sensitization a dramatic decrease in the amount of water-soluble proteins with the mobility of 0.54, 0.42, 0.40 and membrane protein with the molecular weight of 24000 kD was observed. Such a decrease appears to reflect the stage nature of long-term sensitization and to be linked with shifts in the functional characteristics of some cellular elements of snail central nervous system.     

Stability of the population variants of the B-chromosome system in the East-Asian mouse Apodemus peninsulae from the Baikal region and Northern Mongolia

Analysis of the B-chromosome frequency and morphotypes in 160 mice Apodemus peninsulae from 17 localities of the Baikal region, Northern Mongolia, Trans-Baikalia, and the Russian Far East showed that the mice were from five geographical populations. The interpopulation difference was determined by variations of 0?C4 macro B chromosomes and 0?C11 micro B chromosomes. The B-chromosome number and morphotypes proved to be stable over the past 30 years in the geographical populations under study.