O dealkylation and aliphatic and aromatic hydroxylation of 3-methoxy-17 beta-estradiol by Aspergillus alliaceus

Aspergillus alliaceus UI 315 was examined for its ability to metabolize 3-methoxy-17 beta-estradiol. Preparative-scale incubations with this substrate afforded good yields of 6 beta-hydroxy-17 beta-estradiol, 4-hydroxy-17 beta-estradiol, and 4,6 beta-dihydroxy-17 beta-estradiol, which were identified by high-pressure liquid chromatography, 1H and 13C nuclear magnetic resonance, and high-resolution mass spectrometry.     

Agonistic behaviours in colonies of the bumblebeeBombus terrestris

The first aim of this study was to investigate whether specific changes in the frequencies of behavioural characteristics are correlated with the cause or reflect the onset of the laying of haploid eggs by the queen, and whether these changes cause the onset of egg laying and aggressive behaviour by workers. The second aim was to obtain a better understanding of the occurrence of the behaviours in relation to the physiology and function of the queen and the workers. No behavioural characteristics of workers which could predict the occurrence of the queen's switch to haploid egg laying was found nor did any such behaviour indicate that the switch had already occurred. The onset of worker oviposition was not found to be the consequence of the level or the type of agonistic actions between the workers and the queen. With the onset of worker oviposition the agonistic behaviours called trembling and buzzing, which are directed at the queen, disappear. At the same time the frequency of a non-directed behaviour, called humming, increases. This behaviour is seen particularly in the small housebees with developed ovaries. Before worker oviposition begins, the frequencies with which individual workers perform agonistic behaviour are not correlated with the conditions of their ovaries nor correlated with other characteristics of the workers. However, these frequencies are related to the sequence in which workers emerge. The correlations with age are due to the fact that workers of the first brood have higher activity levels than those of the later broods. The first egg layers are to be found among the first workers. In the period of worker oviposition, humming and the aggressive behaviours of darting and attack are performed by workers with developed ovaries. These behaviours are directed particularly towards workers who also have active ovaries. If the queen has disappeared 1 worker usually becomes dominant. This worker is characterized by the relatively high frequency with which she engages in darting and attacks. In addition, this worker is characterized by a specific behaviour, called pumping, which is directed at workers that have mature eggs in their ovaries. Behavioural domination, however, is no guarantee that the bee concerned will eventually become the most productive one. Although at an apparently pre-determined moment in the ontogeny of the colony the queen loses control over worker oviposition and related behaviours, she remains dominant in various other behavioural hierarchies. It is therefore concluded that the queen never loses dominance completely.     

Can a simple function for the dielectric response model electrostatic effects in globular proteins?

The relationship between the effective dielectric constant that models the electrostatic effect from a charged side chain in a protein was evaluated both experimentally and theoretically. Experimental values were obtained from the shifts in pKa that resulted from point mutations of side chains in subtilisin. Theoretical values were obtained from an iterative solution to Poisson's equation that considers the dielectric response of the protein and the solvent together with charge positions. There is no simple relationship between the effective dielectric constant and the distance from the charge responsible for the interactions. For some charge positions a linear but not a direct proportional relationship of the effective dielectric with distance of separation was observed. Thus, simple models such as a linear distance-dependence for the dielectric response are not suitable to evaluate electrostatic effects in proteins.     

Production of trichothecene and non-trichothecene mycotoxins by Fusarium species isolated from maize in Minnesota

Eighty-two cultures of Fusarium species isolated in 1986 from moldy maize in Minnesota were each cultured on rice for 4 weeks and found to produce the following mycotoxins: F. graminearum isolates, deoxynivalenol (DON, 4–225 g/g), 3-acetyldeoxynivalenol (3-ADON, 2–4g/g), 15-acetyldeoxynivalenol (15-ADON, 1–35 g/g) and zearalenone (ZEA, 5–4350 g/g); F. moniliforme, fusarin C (detectable amounts to 1000 g/g); F. mòniliforme, F. oxysporum, F. proliferatum and F. subglutinans isolates, moniliformin (15–6775 g/g); F. moniliforme, F. proliferatum, and F. subglutinans isolates, fusaric acid (detectable amounts). Other mycotoxins screened for in each rice sample and not detected were T-2 toxin, HT-2 toxin, neosolaniol, T-2 tetraol, nivalenol, fusarenon-X, scirpenols, alpha and beta trans-zearalenols, wortmannin, and fusarochromanone. The rat feeding bioassay indicated that other, unidentified toxins may be present.     

Radiolysis of DNA in aqueous solution in the presence of a scavenger: A kinetic model based on a nonhomogeneous reaction of OH radicals with DNA molecules of spherical or cylindrical shape

Summary Two expressions are given for the survival dose of DNA exposed to high-energy radiation in aqueous solution in the presence of a scavenger. They are derived from a model where a diffusion controlled reaction of OH radicals occurs on the surface of the DNA macromolecules in competition with scavenging in the bulk of the solution. The DNA molecules are approximated either by spheres or by cylinders. The model based on molecules of spherical shape corresponds closely to that developed by van Rijn et al. [20]. Expressions obtained from the cylindrical model are used to account for the dependence on the scavenger concentration of some experimentally measured quantities, namely the survival dose and theG value for single-strand breaks upon Co -irradiation ofX 174 DNA and polyadenylic acid, respectively.In memoriam Prof. Dr. O.E. Polansky     

Influence of diet and monensin on development of anaerobic fungi in the rumen, duodenum, cecum, and feces of cows

Three cows with fistulated rumens, duodenums, and ceca were fed five different diets: lucerne hay, lucerne hay plus whey (40:60), lucerne hay plus beets (50:50), corn silage plus monensin (40 ppm [40 g/kg] of dry matter intake), and lucerne hay plus monensin (80 ppm of dry matter intake). The fungal population was observed in the rumen, duodenum, cecum, and rectum and varied with diet; it was most abundant with lucerne hay alone and with corn silage plus monensin. The proportion of particles colonized by fungi in the duodenum, the cecum, and feces was measured by microscopic observation and varied from 5 to 50%, depending on the diet. The further sporangia attached to the plant particles were from the rumen, the more likely they were to be devoid of spores. Results confirmed the influence of diet on the development of the ruminal fungal population and showed that monensin does not eliminate these microorganisms. They also confirmed the presence of anaerobic fungi in the ruminant intestine. It is likely that anaerobic fungi leave the rumen attached to plant particles. However, large colonies of nonrhizoidal-type fungi were observed in cecum samples and in feces; at these sites, environmental conditions are perhaps more favorable for this type of fungus than they are in the rumen.     

New aspects on the distribution and metabolism of essential trace elements after dietary exposure to toxic metals

Under present environmental conditions, an increase in pollution owing to metals such as cadmium (Cd), lead (Pb), and methylmercury (MeHg) must be expected. The resulting effects would be seen particularly in the food chain. The daily intake of toxic metals in various parts of the world is different and depends on both the dietary habits and the concentration in foodstuffs. Oral ingestion of these toxic metals perturbs the metabolism of essential elements, especially zinc (Zn), copper (Cu), iron (Fe), and selenium (Se). The elemental composition of body tissues and fluids is an indicator of the nutritional and pathological status of humans. This review will describe the dietary intake and gut absorption of essential and toxic elements. Furthermore, it will discuss threshold values, toxic effects in relation to body burden of toxic metals, the biological indices of exposure, and the interaction between toxic and essential elements. The overall ratio of Cu, Zn, Fe, and Se concentration to Cd in the human kidney is the lowest in comparison to Hg and Pb. Increased kidney copper and urinary losses may be common denominators in the manifestation of renal toxicity induced by heavy metals. Factors affecting availability and loss of copper should be identified and measured. The critical kidney concentration for Cd, Pb, and MeHg should be revised in relation to essential elements.     

Selenium-containing proteins of rat kidney and liver microsomes

Selenium (Se)-containing proteins in microsomal fractions of rat kidney and liver were investigated after isotopic labeling of rats with [75Se]selenite. More than 85% of the 75Se in the solubilized microsomal extracts precipitated with protein after trichloroacetic acid treatment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), used to separate the labeled protein subunits in the solubilized microsomal extracts, revealed several 75Se-containing proteins in addition to glutathione peroxidase. 75Se-labeled subunits with molecular weights of 55, 30, 26, 22, 19, and 17 kDa were present in microsomal fractions of kidney and liver. The 75Se-labeled tryptic peptide of the 55 kDa subunit had the same Rf value on a 17% SDS-PAGE gel as the peptide from plasma selenoprotein P. A time-course study of the labeling of individual protein subunits in kidney and liver microsomes from Se-supplemented and Se-deficient rats showed that most of the 75Se was associated with the 55 kDa subunit 3 hr after injection. The amount of 75Se associated with this protein subunit decreased by 12 hr, with a concurrent increase in the labeling of lower molecular-weight subunits. The results support the hypothesis that there is a mechanism for transfer of Se from the 55 kDa subunit to other Se-containing proteins.     

The paradox of seed size and adaptation

Correlations between habitat and seed size suggest that this character is adaptive. Mean seed size is a relatively invariant species characteristic and seed size has marked effects upon fitness. These observations have previously led to the conclusion that seed size is under stabilizing selection. This conclusion, originally based mainly on evidence from crop plants grown in controlled environments, is questioned here on the grounds that recent studies of wild plants show marked phenotypic plasticity and low heritability of seed size. If seed size is not readily altered by natural selection in the wild, then its effects on fitness are evidence that this character is a constraint on habitat distribution. Constancy of mean seed size may be due to developmental canalization to a size set by previous selection, rather than a continuing process of stabilizing selection.     

Differential distribution of alpha-tubulin isotypes in Euplotes eurystomus determined by confocal immunofluorescence microscopy

Detergent permeabilized Euplotes eurystomus (a fresh water hypotrichous ciliate) was reacted with monoclonal and polyclonal antibodies specific for either detyrosinated or tyrosinated alpha-tubulin (Glu- or Tyr-tubulin). The isolated cytoskeleton-nuclear complex was examined by Western immunoblotting and by immunofluorescent and electron microscopic methods. Both Glu- and Tyr-tubulins were detected by immunoblot analysis. Immunofluorescent microscopy indicated that the alpha-tubulin isotypes are concentrated in different regions of permeabilized cells: Glu-tubulin is located primarily in cirri, membranelles, and surrounding the macro- and micronuclei. Tyr-tubulin is principally at the bases of cirri and membranelles. This differential distribution of alpha-tubulin isotypes is discussed in terms of current concepts concerning the correlation of tubulin post-translational modifications to microtubule stability. Confocal immunofluorescent imaging was of critical importance in clearly differentiating the Glu-tubulin isotype surrounding the macro- and micronuclei from a brilliantly fluorescent environment originating from cytoskeletal structures. In conjunction with conventional and stereo-electron microscopy, confocal optical microscopy provided convincing evidence for a "basket" of microtubules surrounding both nuclei.