New evidences for participation of biogenic monoamines in androgen-dependent sexual differentiation of hypothalamic control of gonadotropin secretion in rats.

Corpora lutea have been found in the ovarian tissue transplanted into the anterior ocular chamber of castrated two-month-old male rats receiving on 3rd through 7th post-natal days alpha-methyl-p-tyrosine or p-chlorophenylalanine. Administration of these agents in combination with testosterone propionate to newborn female rats prevented essentially development of the anovulatory syndrome and maintained a normal picture of vaginal smears, ovarian and uterine structure as well as cyclic changes of adenohypophyseal and blood plasma lutropin contents and normal levels of estradiol and progesterone in the blood plasma except of progesterone level in animals receiving alpha-methyl-p-tyrosine. The preventive effect of the adrenoblocking agents droperidol and propranolol was weak and inconstant. Results suggest participation of catecholamines and serotonin in the androgen-dependent sexual differentiation of the brain in rats.     

Formaldehyde dehydrogenase from the recombinant yeast Hansenula polymorpha: isolation and bioanalytic application

A recombinant yeast clone, a derivative of the recipient Hansenula polymorpha strain NCYC 495, was chosen as an NAD and glutathione-dependent formaldehyde dehydrogenase overproducer. Optimal cultivation conditions for the highest yield of enzyme were established. A simple scheme for the isolation of formaldehyde dehydrogenase from the recombinant strain was proposed, and some characteristics of the purified enzyme were studied. An enzymatic method for formaldehyde assay based on formaldehyde dehydrogenase was developed and used for testing real samples.     

Phytochelatin synthase, a dipeptidyltransferase that undergoes multisite acylation with gamma-glutamylcysteine during catalysis: stoichiometric and site-directed mutagenic analysis of arabidopsis thaliana PCS1-catalyzed phytochelatin synthesis

Phytochelatin (PC) synthase has been assumed to be a gamma-glutamylcysteine dipeptidyl transpeptidase (EC 2.3.2.15) and, more recently, as exemplified by analyses of the immunopurified recombinant enzyme from Arabidopsis thaliana (AtPCS1-FLAG), has been shown to catalyze a PC synthetic reaction with kinetics that approximates a bisubstrate-substituted enzyme mechanism in which millimolar concentrations of free GSH and micromolar concentrations of heavy metal.GSH thiolates (e.g. cadmium.GS(2)) or millimolar concentrations of S-alkylglutathiones serve as cosubstrates. Here, we show, by direct analyses of the stoichiometry of AtPCS1-FLAG-catalyzed PC synthesis, the kinetics and stoichiometry of acylation of the enzyme and release of free glycine from gamma-Glu-Cys donors, and the effects of the Cys-to-Ser or -Ala and Ser-to-Ala substitution of conserved residues in the catalytic N-terminal half of the enzyme, that PC synthase is indeed a dipeptidyltransferase that undergoes gamma-Glu-Cys acylation at two sites during catalysis, one of which, in accord with a cysteine protease model, likely corresponds to or is at least tightly coupled with Cys(56). The identity of the second site of enzyme modification remains to be determined, but it is distinguishable from the first Cys(56)-dependent site, which is amenable to gamma-Glu-Cys acylation by free GSH, because its acylation not only depends on the provision of Cd(2+) or GSH with a blocked, S-alkylated thiol group, but is also necessary for net PC synthesis. We conclude that des-Gly-PCs are not generated as an immediate by-product, but rather that the enzyme catalyzes a dipeptidyl transfer reaction in which some of the energy liberated upon cleavage of the Cys-Gly bonds of the gamma-Glu-Cys donors in the first phase of the catalytic cycle is conserved through the formation of a two site-substituted gamma-Glu-Cys acyl-enzyme intermediate whose hydrolysis provides the energy required for the formation of the new peptide bond required for the extension of PC chain length by one gamma-Glu-Cys repeat per catalytic cycle.     

Activities of the enzymes of formaldehyde catabolism in recombinant strains of <Emphasis Type="Italic">Hansenula polymorpha</Emphasis>

Activities of the enzymes of formaldehyde (FA) catabolism in recombinant strains of the methylotrophic yeast Hansenula polymorpha overproducing NAD⁺- and glutathione-dependent formaldehyde dehydrogenase (FADH) were studied under different cultivation conditions and at elevated FA content. Southern dot-blot analysis confirmed the presence of six to eight copies of the target FLD1 gene in stable recombinant clones of H. polymorpha. Under certain cultivation conditions, the transformants resistant to elevated FA concentrations were shown to produce FADH and other bioanalytically important enzymes: formate dehydrogenase, alcohol dehydrogenase, alcohol oxidase, and formaldehyde reductase. The optimal cultivation conditions for recombinants were determined, resulting in maximum synthesis of FADH: methanol as a carbon source, methylamine as a nitrogen source, FA as an inducer, temperature of 37°C, and cells in the early exponential phase of growth.     

Absorption of Cadmium and Lead Ions by Gametophyte of the MossPlagiomnium undulatum

A cytochemical analysis of heavy-metal distribution was used to establish an increased ability of the marginal and midrib cells of moss leaves to accumulate metal ions from solutions of lead and cadmium nitrate. The adjacent leaf cells accumulated metal ions more slowly. As shown by the color reaction produced by metal–dithizone complex, the concentration of the absorbed metal ions in the cells increased more than 100-fold as compared to the salt concentration in the solution. The morphological differentiation of the marginal and midrib cells was closely related to the cytosolic pH value and the absorption capacity of cells. Metal ions absorbed in excess of the capacity of absorption sites were not bound by cells and readily washed out.     

Behavior of amyloplasts in photo- and gravitropism of the moss protonema

The protonema of mosses Ceratodon purpureus and Pottia intermedia is negatively gravitropic in darkness and grows on the substrate surface under illumination. However, the putative mechanisms of these growth responses are not well understood so far. For gravitropism, sedimentation of amyloplasts has been widely assumed to be the first step of the signal transduction chain. This model was supported by numerous observations where amyloplasts' number or size in a protonema apical cell correlated with its gravisensitivity. Unlike multicellular graviperceptive organs, a protonema apical cell is the same site for both of gravity and light perception and realization of growth movements. In addition, red light is known to change the cell responses to gravity. Therefore, we analysed the influence of red light on the events associated with graviperception and growth movements of protonema apical cells, namely: plastid behavior, size, and number, starch content, chlorophyll fluorescence intensity and alpha-amylase activity, under gravistimulation of dark-grown protonema.     

Morphological convergence of shell shape in distantly related scallop species (Mollusca: Pectinidae)

Morphological convergence is a central concept in evolutionary biology, but convergent patterns remain under‐studied in nonvertebrate organisms. Some scallop species exhibit long‐distance swimming, a behaviour whose biomechanical requirements probably generate similar selective regimes. We tested the hypothesis that shell shape similarity in long‐distance swimming species is a result of convergent evolution. Using landmark‐based geometric morphometrics, we quantified shell shape in seven species representing major behavioural habits. All species displayed distinct shell shapes, with the exception of the two long‐distance swimmers, whose shells were indistinguishable. These species also displayed reduced morphological variance relative to other taxa. Finally, a phylogenetic simulation revealed that these species were more similar in their shell shape than was expected under Brownian motion, the model of character evolution that best described changes in shell shape. Together, these findings reveal that convergent evolution of shell shape occurs in scallops, and suggest that selection for shell shape and behaviour may be important in the diversification of the group. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 571–584.