European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Cytogenetic effects of low dose radiation with different LET in human peripheral blood lymphocytes and possible mechanisms of their realization

The induction of chromosome damage by the exposure to low doses of gamma-(60)Co and accelerated carbon ions 12C in peripheral blood lymphocytes of different donors was investigated. The complex nonlinear dose-effect dependence at the range from 1 to 50-70 cGy was observed. At the doses of 1-5 cGy the cells show the highest radiosensitivity (hypersensitivity), mainly due to the chromatid-type aberration, which is typical to those spontaneously generated in the cell and believed not to be induced by the irradiation of unstimulated lymphocytes according to the classical theory of aberration formation. With the increasing dose the frequency of the aberrations decreases significantly, in some cases up to the control level. At the doses over 50-70 cGy the dose-effect curve becomes linear. The possible role of the oxidative stress, caused by radiation-induced increase in mitochondrial reactive oxigen species (ROS) release in the phenomenon of hypersensitivity (HS) at low doses is discussed as well as cytoprotective mechanisms causing the increased radioresistance at higher doses.     

Calculation of Biodiesel Fuel Characteristics Based on the Fatty Acid Composition of the Lipids of Some Biotechnologically Important Microorganisms

The interdependences between the structure of fatty acid and biofuel characteristics obtained from these fatty acids were briefly reviewed. The fatty acid compositions of the lipids of yeasts and phototrophic microorganisms were analyzed. The main parameters of the biodiesel (iodine value, cetane number, and kinematic viscosity) that can be made from the lipids of these microorganisms were calculated based on the data and compared to the current standards. The lipids of the yeast Rhodosporidium toruloides VKPM Y-3349 were shown to be the most suitable for biofuel production due to the composition and content of fatty acid. The possibilities of a decrease in the prime cost of microbial lipids (along with plant oils) that would make them competitive raw material for biofuel production were considered.     

ONTOGENETIC NICHE SHIFT IN THE BRACHIOPOD TEREBRATALIA TRANSVERSA: RELATIONSHIP BETWEEN THE LOSS OF ROTATION ABILITY AND ALLOMETRIC GROWTH

Abstract: Many articulated brachiopods experience marked life habit variations during ontogeny because they experience their fluid environment at successively higher Reynolds numbers, and they can change the configuration of their inhalant and exhalant flows as body size increases. We show that the extant brachiopod Terebratalia transversa undergoes a substantial ontogenetic change in reorientation governed by rotation around the pedicle. T. transversa′s reorientation angle (maximum ability to rotate on the pedicle) decreases during ontogeny, from 180 degrees in juveniles to 10–20 degrees in individuals exceeding 5 mm, to complete cessation of rotation in individuals larger than 10 mm. Rotation ability is substantially reduced after T. transversa achieves the adult lophophore configuration and preferred orientation with respect to ambient water currents at a length of 2.5–5 mm. We hypothesize that the rotation angle of T. transversa is determined mainly by the position of ventral and dorsal points of attachment of dorsal pedicle muscles relative to the pedicle. T. transversa shows a close correlation between the ontogenetic change in reorientation angle and ontogeny of morphological traits that are related to points of attachment of dorsal pedicle muscles, although other morphological features can also limit rotation in the adult stage. The major morphological change in cardinalia shape and the observed reduction of rotation affect individuals 2.5–10 mm in length. The position of ventral insertions of dorsal pedicle muscles remains constant, but contraction of dorsal pedicle muscles is functionally handicapped because dorsal insertions shift away from the valve midline, rise above the dorsal valve floor, and become limited by a wide cardinal process early in ontogeny (<5 mm). The rate of increase of cardinal process width and of distance between dorsal pedicle muscle scars substantially decreases in the subadult stage (5–10 mm), and most of the cardinalia shell traits grow nearly isometrically in the adult stage (>10 mm). T. transversa attains smaller shell length in crevices than on exposed substrates. The proportion of small‐sized individuals and population density is lower on exposed substrates than in crevices, indicating higher juvenile mortality on substrates prone to grazing and physical disturbance. The loss of reorientation ability can be a consequence of morphological changes that strengthen substrate attachment and maximize protection against biotic or physical disturbance (1) by minimizing torques around the pedicle axis and/or (2) by shifting energy investments into attachment strength at the expense of the cost involved in reorientation.     

Interaction of the haloalkaliphilic purple bacteria <Emphasis Type="Italic">Rhodovulum steppense</Emphasis> with aluminosilicate minerals

The interaction was investigated between the haloalkaliphilic nonsulfur purple bacteria Rhodovulum steppense A-20s^T and layered aluminosilicates: micas (biotite, phlogopite, and muscovite) and clay minerals (montmorillonite and kaolinite). The interaction between all components of this system (minerals, water, medium, and bacteria) resulted in the changes in the chemical composition of the minerals and solutions. These changes were especially significant in the presence of bacteria. By using some elements for growth and promoting their transfer into the exchange pool of the minerals, bacteria removed these elements from the medium. The content of exchange bases in the aluminosilicates incubated in the presence of bacteria was several times higher than in the minerals incubated in sterile medium. The observed saturation of the mineral phase with potassium and magnesium may be considered the initial phase of diagenesis of the aluminosilicates under study.     

A biosensor for environmental genotoxin screening based on an SOS lux assay in recombinant Escherichia coli cells.

A genetically controlled luminescent bacterial reporter assay, the SOS lux test, was developed for rapid detection of environmental genotoxins. The bioassay is based on the recombinant plasmid pPLS-1, which was constructed as a derivative of pBR322, carrying the promoterless luxCDABFE genes of Photobacterium leiognathi downstream of a truncated cda gene from ColD with a strong SOS promoter. E. coli recA+ strains containing this construction are inducible to high levels of light production in the presence of substances or agents that cause damage to the DNA of the cells. The light signal, reflecting the SOS-inducing potency, is recorded from the growing culture within 1 s, and the test results are available within 1 to 2 h. Induction of bioluminescence was demonstrated by treatment of E. coli C600(pPLS-1) with 6 genotoxic chemicals (mitomycin C, N-methyl-N'-nitro-N-nitrosoguanidine, nalidixic acid, dimethylsulfate, hydrogen peroxide, and formaldehyde) and with UV and gamma radiation. A clear dose-response relationship was established for all eight genotoxins. The sensitivity of the SOS lux test is similar to that of other bioassays for genotoxicity or mutagenicity, such as the SOS chromotest, umu test, and Ames mutatest. These results indicate that the SOS lux test is potentially useful for the in situ and continuous detection of genotoxins.     

Immobilized glucoamylase: A biocatalyst of dextrin hydrolysis

Heterogeneous biocatalysts of starch saccharification based on glucoamylase and carbon-containing carriers were obtained, and their biocatalytic properties in the enzymatic hydrolysis of corn dextrins were studied. It was shown that the morphology of the surface carbon layer of carriers markedly affected the properties of biocatalysts. Glucoamylase immobilized by adsorption on the surface of carriers covered with a layer of catalytic filamentous or pyrolytic carbon had the maximum enzymatic activity and stability, whereas biocatalysts prepared on the basis of carriers that had no carbon layer or were covered with graphite-like surface carbon had a low activity and stability.     

Induction of chromosome aberrations and micronuclei in human peripheral blood lymphocytes at low dose of radiation

The chromosome damage induced by the doses of y-irradiation 6)Co in peripheral blood lymphocytes was studied using different cytogenetic assays. Isolated lymphocytes were exposed to 0.01-1.0 Gy, stimulated by PHA, and analysed for chromosome aberrations at 48 h postirradiation by metaphase method, at 49 h--by the anaphase method, at 58 h by micronucleus assay with cytochalasin B and, additionally, micronuclei were counted at 48 h on the slides prepared for the metaphase analysis without cytochalasin B. Despite of the quantitative differences in the amount of chromosome damage revealed by different methods all of them demonstrated complex nonlinear dose dependence of the frequency of aberrant cells and aberrations. At the dose range from 0.01 Gy to 0.05-0.07 Gy the cells had the highest radiosensitivity mainly due to chromatid-type aberration induction. With dose increasing the frequency of the aberrant cells and aberrations decreased significantly (in some cases to the control level). At the doses up to 0.5-0.7 Gy the dose-effect curves have become linear with the decreased slope compare to initial one (by factor of 5 to 10 for different criteria) reflecting the higher radioresistance of cells. These data confirm the idea that the direct linear extrapolation of high dose effect to low dose range--the procedure routinelly used to estimate genetic risk of low dose irradiation--cannot be effective and may lead to underestimation of chromosome damage produced by low radiation doses. Preferences and disadvantages of used cytogenetic assays and possible mechanisms of low ionising radiation doses action were discussed.