Recent history of Lake Ladoga

Combined paleolimnological investigations of a 1.8 m sediment core from the deepest north-western part of Lake Ladoga show stratigraphic changes in granulometric and chemical composition, organic matter content, diatom species composition and chlorophyll a concentration. The sediment accumulation rate was calculated and 5 stages of lake history over the last 4 000 years were described. Changes in lake environment were mainly caused by changes in climate and lake water balance. Human impact on the lake was also traced.     

The role of the lateral and medial hypothalamus in reproducing a motor reaction as the signal during the acquisition of classical conditioned reflexes]

In experiments on three dogs there was shown that testing electrostimulation of the lateral hypothalamus reproduced the motor reaction which is a signal stimulus at elaboration of classic alimentary conditioned reflexes (CRs) and did not reproduce it at elaboration of classic defensive CR. Testing electrostimulation of medial parts of the hypothalamus reproduced, as LH electrostimulation the "signal" motor reaction, but in less percentage of cases, during elaboration of classic alimentary CRs and did not reproduce it at elaboration of classic defensive CRs. The reproduction of the signal motor reaction at LH electrostimulation is connected with activation of backward conditioned connection from motivation structures of the hypothalamus to representation of the signal stimulus in the motor cortex.     

CD spectra of isoionic DNA solutions

The ion-exchange transition of Na-DNA----H-DNA in concentrated salt-free solutions is accompanied by strong variations in CD spectra. The rotational force of the negative band magnitude of delta epsilon 249 decreases when going to H-DNA by about 4 times, and the value of delta epsilon 279, by 1.2 times. These changes are irreversible to a considerable extent, which is evident because the spectra of Na-DNA obtained by neutralizing isoionic H-DNA solutions with NaOH or by the ion-exchange method significantly differ from those of Na-DNA taken by dissolving solid Na-DNA in deionized water. It has been shown that additions of NaCl to an isoionic solution of DNA leads to variations of spectra, typical for deprotonation processes as well as for an increase in DNA hydration.     

Colorimetric estimation of diamine oxidase activity.

A simple colorimetric method for estimation of DAO activity with 4-nitrobenzylamine as a substrate (9,10) was developed. Sensitivity of this method, based on conversion of the aldehyde formed in course of the enzymatic reaction into its 4-nitrophenylhydrazone with subsequent measuring of optical density at 590 nm in strongly alkaline medium, exceeded about 25-fold that of the conventional colorimetric procedure for estimation of DAO activity (14).Sensitivity of the spectrophotometric method for estimation of DAO activity with 4-dimethylaminomethylbenzylamine as a substrate (4) was increased about fivefold by conversion of the aldehyde formed in course of the enzymatic reaction into its 4-nitrophenylhydrazone with subsequent measuring of optical density at 530 nm in strongly alkaline medium.     

Carbon monoxide inhibits superoxide dismutase and stimulates reactive oxygen species production by Desulfovibrio desulfuricans 1388

The hypothesis that oxidative stress characterized by enhanced superoxide generation underlies the toxicity of some factors to living organisms has been investigated. It is shown that CO (5-6% in gas phase) changed some growth parameters (mu, t(d)) of the sulfate-reducing bacterium Desulfovibrio desulfuricans 1388. Enhanced O(2)(-) generation registered by EPR spectroscopy and adrenochrome method was observed when cells were incubated under CO. The SOD activity in cells from the exponential growth phase growing under CO was decreased 1.5-fold compared with the control cells growing under Ar. SOD activities in cells from the stationary growth phase growing with or without CO were comparable. The results support the concept that CO toxicity for sulfate-reducing bacteria is an oxidative stress that arises in cells oxidizing CO to CO(2).     

Significance of initial emotional state for neuroimmunomodulation under conditions of activation or blockade of 5-HT1A receptors

Selective agonist of 5-HT1A receptors--8-OH-DPAT (1 mg/kg) induced a suppression of the immune reaction in aggressive male CBA mice immunized with SRBC (5 x 10(8)). In submissive mice with 10-day defeat experience in confrontation tests, the activation of 5-HT1A receptors with 8-OH-DPAT did not alter the immune response, whereas the application of selective antagonist of 5-HT1A receptors WAY-100635 increased the immune reaction only in submissive mice. It is concluded that activation or blockade of 5-HT1A receptors produced different effects on the immune function of CBA mice depending on the initial emotional state which is known to be provided in aggressive and submissive animals by different activities of the brain neurotransmitter systems including the 5-HTergic system.     

A study of the effect of irradiation hardness on the properties of the fluoropolymeric matrix modified by polyanionic biologically active substances

The properties of a synthetic substrate responsible for the behavior of substrate-dependent cells in the culture were studied. The effect of the composition of a system water-soluble biopolymer (sodium alginate or methyl cellulose)-synthetic latex SKF-26 and the effect of various types of radiations on its biophysical properties were studied. The results obtained indicate that the addition of water-soluble biopolymeric additives to synthetic polymeric films improves the adhesion of cells to the substrate, the adhesion being closely related to the concentration of additives. It was found that the modification methods that determine changes in the charge of the substrate affect the capacity of different cell types for adhesion and proliferation. It was also found that the hardness of irradiation does not affect the vapor permeability and the extent of film swelling.     

Early plant growth and biochemical responses induced by <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> Sp245 lipopolysaccharides in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) seedlings are attenuated by procyanidin B2

This study analyzes the effects of procyanidin B2 on early wheat plant growth and plant biochemical responses promoted by lipopolysaccharides (LPS) derived from the rhizobacteria Azospirillum brasilense Sp245. Measurements of leaf, root length, fresh weight, and dry weight showed in vitro plant growth stimulation 4 days after treatment with A. brasilense as well as LPS. Superoxide anion (O₂ ^·?) and hydrogen peroxide (H₂O₂) levels increased in seedling roots treated with LPS (100 μg mL^?1). The chlorophyll content in leaf decreased while the starch content increased 24 h after treatment in seedling roots. The LPS treatment induced a high increase in total peroxidase (POX) (EC 1.11.1.7) activity and ionically bound cell wall POX content in roots, when compared to respective controls. Early plant growth and biochemical responses observed in wheat seedlings treated with LPS were inhibited by the addition of procyanidin B2 (5 μg mL^?1), a B type proanthocyanidin (PAC), plant-derived polyphenolic compound with binding properties of LPS. All results suggest first that the ionically bound cell wall POX enzymes could be a molecular target of A. brasilense LPS, and second that the recognition or association of LPS by plant cells is required to activate plant responses. This last event could play a critical role during plant growth regulation by A. brasilense LPS.     

Structure of the style and pollen tube pathway in the Ziziphoid and Rhamnoid clades of Rhamnaceae

The ultrastructure of the style and pollen tube pathway before, during and after anthesis were studied in 13 species belonging to the tribes Pomaderreae, Paliureae, Colletieae and Gouanieae (Ziziphoid clade) and Rhamneae (Rhamnoid clade) using light microscopy and transmission electron microscopy. The aim of this study is to provide new morphological characters useful for phylogenetic analysis at suprageneric level in Rhamnaceae. The patterns of pollen tube growth and the ultrastructural changes undergone by cells of the style were also described. Species of Rhamneae (Scutia buxifolia and Condalia buxifolia) have a solid style, with the transmitting tissue forming three independent strands (S. buxifolia) or a central, single horseshoe-shaped strand as seen in transversal section (C. buxifolia) which could derive from the fusion of formerly independent strands. In contrast, Pomaderreae, Gouanieae and Paliureae showed semi-solid styles, while in Colletieae, as previously reported, the style is hollow with two or three stylar canals. The style anatomy and the ultrastructure of the pollen tube pathway show that there is a tendency towards a solid style with a single strand of transmitting tissue within the family. The three-canalled hollow style could be the plesiomorphic state of the character “type of style” in the family, the semi-solid style the synapomorphic state and the solid style with three strands of transmitting tissue the apomorphic state, with the solid style with a single strand of transmitting tissue as the most derived state. Therefore, Colletieae would be the most basal tribe of the Ziziphoid clade.     

Ring chromosomes: from formation to clinical potential

Ring chromosomes (RCs) are circular DNA molecules, which occur rarely in eukaryotic nuclear genomes. Lilian Vaughan Morgan first described them in the fruit fly. Human embryos very seldom have RCs, about 1:50,000. Carriers of RCs may have varying degrees of symptoms, from healthy phenotype to serious pathologies in physical and intellectual development. Many authors describe common symptoms of RC presence: short stature and some developmental delay that could be described as a “ring chromosome syndrome.” As a rule, RCs arise de novo through the end-joining of two DNA double-strand breaks, telomere-subtelomere junction, or inv dup del rearrangement in both meiosis and mitosis. There are family cases of RC inheritance. The presence of RCs causes numerous secondary chromosome rearrangements in vivo and in vitro. RCs can change their size, become lost, or increase their copy number and cause additional deletions, duplication, and translocations, affecting both RCs and other chromosomes. In this review, we examine RC inheritance, instability, mechanisms of formation, and potential clinical applications of artificially created RCs for large-scale chromosome rearrangement treatment.