Transfer of Cl from herbage into tissues and milk products of dairy cattle and pigs

Cl-36 is an important component of nuclear waste. The concentrations of stable chlorine (Cl) in pig and cow tissues were measured to provide information which can be used to parameterize models of ³⁶Cl transfer into agricultural animals. The concentration of stable Cl in cows’ milk was 1.0 ± 0.2 g L⁻¹, in cow muscle it was 0.7 ± 0.2 g kg⁻¹ wet mass (wm) and in pig muscle 0.4 ± 0.1 g kg⁻¹ wm. The concentration of stable Cl in cow and pig liver was 0.9 ± 0.3 g kg⁻¹ wm, which was about two-fold higher than that in the kidney and lung. Due to homeostatic control, stable Cl concentrations in animal tissues are not related to the amount ingested daily in herbage at intake rates in the normal physiological range of up to 188 g day⁻¹ for cows and up to 40 g day⁻¹ for pigs. Therefore, the commonly used transfer coefficient is not suitable for use in quantifying the transfer of ³⁶Cl to milk and meat. Since the metabolism of stable Cl and ³⁶Cl in an animal’s body is identical, the average equilibrium ratios of ³⁶Cl to stable Cl in the daily ration (³⁶Cl (g kg⁻¹)/Cl (g kg⁻¹)) and animal tissues will be the same. We therefore conclude that the average equilibrium Cl isotopic ratio in the dietary daily intake should be used to predict the contamination of meat and milk with ³⁶Cl.     

The Bioutilization of Thiodiglycol (a Detoxication Product of Mustard Gas): Isolation of Degrading Strains and Investigation of Degradation Conditions

The Alcaligenes xylosoxydans subsp.denitrificans strain TD1 capable of degrading thiodiglycol (TDG), a product of mustard gas hydrolysis, was isolated from soil contaminated with breakdown products of this chemical warfare agent. The selected stable variant of TD1 (strain TD2) can grow on TDG with a lag phase of 4–8 h and a specific growth rate of 0.04–0.045 h^–1. Optimal conditions for the biodegradation of TDG (pH, the concentration of TDG in the medium, and specific substrate loading) were determined. TDG was found to be degraded with the formation of diglycolsulfoxide and thiodiglycolic acid as intermediate products. The data obtained can be used to develop approaches to the bioremediation of mustard gas–contaminated soils.     

Kinetics of interactions between apomyoglobin and phospholipid membrane

The interaction of apomyoglobin and its mutant forms with phospholipid membranes was studied using tryptophan fluorescence and circular dichroism in the far UV region. It is shown that a negatively charged phospholipid membrane can have a dual effect on the structure of protein molecule upon their interaction. On the one hand, the membrane induces denaturation of the protein native structure to its intermediate state, acting as a moderate denaturing agent. On the other hand, it can stabilize the structure of unfolded protein to the same intermediate state, acting as a moderate structuring agent. The kinetics of interaction between apomyoglobin and its mutant forms and the phospholipid membrane depends on the membrane surface charge. Here the interaction rate depends on the concentration of phospholipids vesicles and stability of protein molecule, which increase with a decrease in the latter. The roles of these factors in the folding of membrane proteins and the choice of the targeted delivery pathways for protein drugs are discussed.     

Sugar transport together with environmental conditions controls time lags between xylem and stem diameter changes

In the present study the seasonal patterns of time lags between diurnal xylem and whole stem diameter variations at the top and at the base of two Scots pine trees (Pinus sylvestris L.) were compared. The diameter variations were measured during the summers of 2001 and 2002. Time lags were determined using the cross‐correlation method. The lags were found to vary in time according to the different stages of growth. At the top the xylem lagged behind the whole stem between the beginning of stem growth and the end of shoot growth in both years. In 2001 the time lags at the base showed a similar behaviour during stem growth. That kind of seasonal pattern of the time lags would result from the changes in the sink strength due to changing growth rate at different parts of the tree and the differences in the annual rhythm of growth and water availability in the soil (based on precipitation measurements) between the years 2001 and 2002 were reflected in the patterns. The time lags of shrinking and swelling periods during high and low photosynthetic activity (measured using a shoot chamber) were also compared. It was found, for example, that in 2001 in the middle of the growing season at the top of the tree the whole stem lagged on average 15 min more behind the xylem on the days of high photosynthetic activity than on the days of low or moderate. These results show for the first time that the transportation of carbohydrates and variable sink activity could be detected during the growing season in field conditions using stem and xylem diameter variation measurements. Furthermore, these results provide evidence of the pressure gradient‐driven flow also in the phloem of gymnosperms.     

High molecular and phenotypic diversity in the Merodon avidus complex (Diptera,Syrphidae): cryptic speciation in a diverse insect taxon

This paper examines molecular and phenotypic variability in the widely spread European hoverfly species complex Merodon avidus. Herein, based on the mitochondrial DNA (mtDNA) sequences of the cytochrome c oxidase subunit I (COI) and morphometric wing parameters, M. avidus is shown to comprise a complex of cryptic species, and one variety is redefined as a valid species: M. bicolor Gil Collado, 1930 (as var. of spinipes). The species M. bicolor, M. avidus A, and M. avidus B were clearly delimited based on their wing size. A total of 29 M. avidus and M. bicolor individuals presented 20 mtDNA haplotypes, four of which were shared by M. avidus A and M. avidus B, three were confined to M. bicolor, seven to M. avidus A, and six to M. avidus B. Sequence divergences between lineages occurring in the Balkan and in Spain ranged from 4.93 to 6.0 (uncorrected p in %) whereas divergences between M. avidus A and M. avidus B were 0.26 to 1.56. Divergence among morphologically identified individuals of M. avidus A and M. avidus B species ranged from 0.13 to 1.58, and from 0.13 to 0.52, respectively. The phenotypic substructuring and observed genetic uniqueness of populations in spatially and temporally fragmented M. avidus taxa were used to identify genetic units. The early split of two allopatric lineages, Spanish M. bicolor and Balkan M. avidus, was followed by diversification in each lineage. Present‐day morphological uniformity masks much of the genetic complexity of lineages within the M. avidus complex. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 819–833.     

Morphology and Molecular Phylogeny of Trimyema koreanum n. sp., a Ciliate from the Hypersaline Water of a Solar Saltern

ABSTRACT. A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293‰) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing. Trimyema koreanum is about 30 × 13 μm in vivo, has usually 23 longitudinal ciliary rows forming two distinct ciliary girdles visible both in vivo and in protargol impregnation. A third indistinct ciliary girdle as well as a girdle of mucocysts is distinguishable only in impregnated cells. We suggest T. koreanum as a new species, differing from the most similar species, T. marinum, by the presence of two distinct ciliary girdles (T. marinum usually has six ciliary girdles clearly visible in living cells and three anterior spirals that encircle the cell completely). Although the number of known 18S rRNA sequences in the genus Trimyema was limited, the Trimyema group including T. koreanum forms a strong clade. The phylogenetic position confirms that the isolate belongs to the genus Trimyema and is different from previously sequenced species. Trimyema koreanum is able to consume both prokaryotes and small eukaryotes (specifically, the alga Dunaliella sp.).     

Impact of leaf damage on growth of mountain birch shoots

Canopies of heterophyllous trees expand by production of long shoots. We have previously shown in mountain birch ( Betula pubescens ssp. czerepanovii ) that damage to internode leaves within long shoots does not impede shoot growth, indicating that long-shoot elongation occurs by means of external resources. To study to what extent leaves other than true long-shoot leaves are necessary for the normal growth of mountain birch long shoots, we simulated herbivore damage to the two basal leaves of shoots (which flush simultaneously with short-shoot leaves) and the short-shoot leaves nearest to the long shoot within the branch. Damage to the two basal long-shoot leaves significantly reduced long-shoot growth. Additional damage to short-shoot leaves, situated proximally to the long shoot, did not retard long-shoot growth any more than damage to basal leaves alone. To determine the extent to which short-shoot leaves within a large branch are responsible for the pooled long-shoot production of the branch, we clipped differing proportions of short-shoot leaves from such branches. We found small but significant reduction in the pooled length of the long shoots of the branch, presumably indicating a limited role in long-shoot elongation of current photosynthates within the branch. Our experiments indicate that long shoots are not independent modular units in their carbon economy.     

A Catecholic Siderophore Produced by the Thermoresistant Bacillus licheniformis VK21 Strain

Thermophilic and thermoresistant strains of bacilli were screened on a medium containing Chrome Azurol S for the producers of siderophores. It was found that the Bacillus licheniformis VK21 strain dramatically increases secretion of the metabolite, a chelator of Fe³⁺, in response to addition of manganese(II) salts. The growth of the producer on a minimal medium containing MnSO₄ under the conditions of iron deficiency is accompanied by the accumulation of a catecholic product, the content of which reaches maximum at the beginning of the stationary growth phase of culture. In the presence of FeCl₃, the amount of the catecholic product in the medium considerably decreases. The siderophore, called S_VK21, was isolated from the cultural medium and purified by reversed phase HPLC, and its siderophore function was confirmed by the test for the restoration of growth of producer cells in a medium containing EDTA. The UV spectrum of the siderophore has absorption maxima at 248 and 315 nm. According to the amino acid analysis and NMR spectrometry, the metabolite S_VK21 is 2,3-dihydroxybenzoyl-glycyl-threonine.     

Cloning and Molecular Modeling of Duodenase with Respect to Evolution of Substrate Specificity within Mammalian Serine Proteases That Have Lost a Conserved Active-Site Disulfide Bond

Mammalian serine proteases such as the chromosome 14 (Homo sapiens, Mus musculus) located granzymes, chymases, cathepsin G, and related enzymes including duodenase collectively represent a special group within the chymotrypsin family which we refer to here as "granases". Enzymes of this group have lost the ancient active-site disulfide bond Cys191-Cys220 (bovine chymotrypsinogen A numbering) which is strongly conserved in classic serine proteases such as pancreatic, blood coagulation, and fibrinolysis proteases and others (granzymes A, M, K and leukocyte elastases). We sequenced the cDNA encoding bovine (Bos taurus) duodenase, a granase with unusual dual trypsin-like and chymotrypsin-like specificity. The sequence revealed a 17-residue signal peptide and two-residue (GlyLys) activation peptide typical for granases. Production of the mature enzyme is apparently accompanied by further proteolytic processing of the C-terminal pentapeptide extension of duodenase. Similar C-terminal processing is known for another dual-specific granase, human cathepsin G. Using phylogenetic analysis based on 39 granases we retraced the evolution of residues 189 and 226 crucial for serine protease primary specificity. The analysis revealed that while there is no obvious link between mutability of residue 189 and the appearance of novel catalytic properties in granases, the mutability of residue 226 evidently gives rise to different specificity subgroups within this enzyme group. The architecture of the extended substrate-binding site of granases and structural basis of duodenase dual specificity based on molecular dynamic method are discussed. We conclude that the marked selectivity of granases that is crucial to their role as regulatory proteases has evolved through the fine-tuning of specificity at three levels--primary, secondary, and conformational.