Growth rate, IAA and cytokinin content of wheat seedling after root pruning

Root pruning of wheat seedlings resulted in 2–10 foldincrease in the concentration of IAA in roots ascompared to the control level, which might beresponsible for the observed initiation of lateralroot growth. Cytokinin concentration in xylem sap wasdecreased initially by 60% by pruning in accordancewith the reduction in the hormone-producing organ.Nevertheless cytokinin content in the shoots remainedhigh, which might be due to a decrease in cytokinindecay registered in vitro. A subsequent increasein the export of cytokinins from roots up to thecontrol level demonstrated an elevated ability of thepruned organ to synthesise the hormone. The highcytokinin content in the shoots correlated with theability of the plants to maintain their transpirationand growth at the level of intact plants. Both IAA andcytokinins seem to be important in the restoration ofthe shoot/root balance disturbed by root pruning.     

Effect of excretion-secretion products of some fouling species on the biochemical parameters of blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> L. (Mollusca: Bivalvia) in the White Sea

The effect of excretion-secretion products (ESP) of five abundant fouling invertebrate species (bivalve mollusks Hiatella arctica and Mytilus edulis, solitary ascidia Styela rustica, sponge Halichondria panacea, and sea star Asterias rubens, inhabiting the White Sea) on the biochemical status of blue mussel M. edulis was assessed by the dynamics of lysosomal enzymes activity (nucleases, glycoside hydrolases, and cathepsins). ESP of conspecific species had no effect on the metabolism of the mollusks of this species. ESP of A. rubens, S. rustica, and H. panicea activated the same enzymes. First, acid RNase and glycoside hydrolases activity increased, but in different ways. The metabolites of H. arctica affected the activity of proteometabolism enzymes.     

Effect of the <Emphasis Type="Italic">ipt</Emphasis> gene expression on wheat tolerance to root flooding

The effect of enhanced cytokinin synthesis due to expression of the ipt gene from Agrobacterium tumefaciens on plant tolerance to root flooding was studied. Transgenic wheat (Triticum aestivum L.) plants carrying the ipt gene were more tolerant to flooding than wild-type plants. The effect of transformation was manifested in the higher yield and less growth inhibition during flooding. The measurements of activities of antioxidant enzymes, superoxide dismutase and catalase, as well as MDA content during flooding revealed differences between wild-type and transgenic plants that correlated with their tolerance. These results point to the protective role of cytokinins during wheat root flooding.     

Filamentous Fungi Associated with Bivalve Mollusks from Polluted Biotopes of Ussuriiskii Bay,Sea of Japan

We have studied for the first time the taxonomic composition of filamentous fungi associated with the bivalve mollusks Crenomytilus grayanus (Bunker, 1853) and Modiolus modiolus (Linnaeus, 1758), collected in polluted biotopes of Ussuriiskii Bay (Peter the Great Bay, Sea of Japan). One hundred fifty-five strains of higher fungi were isolated, and 35 species of filamentous fungi were identified. Out of these, 28 species were anamorphous fungi of the genera Aspergillus (12), Penicillium (10), Acremonium (1), Alternaria (1), Aureobasidium (1), and Cladosporium (3) (Deuteromycota), and 7 were species of the genera Chaetomium (6) and Myxotrichum (1) (Ascomycota). Twenty-four species of filamentous fungi were isolated from the internal organs of C. grayanus: 8 from the muscles, 8 from the hepatopancreas, 6 from the female gonads, 4 from the mantle, 3 from the kidneys and male gonads, and 1 from the gills. Twenty-one species of filamentous fungi were isolated from the internal organs of Modiolus modiolus: 10 from the muscles, 6 from the hepatopancreas, 5 from the female gonads, 3 from the kidneys, 3 from the mantle, and 1 from the gills. The bulk of the isolated species of the genera Aspergillus, Penicillium, Cladosporium, and Chaetomium were pathogenic and toxigenic fungi.     

Comparative study of bile acid composition of bile of the European vendace <Emphasis Type="Italic">Coregonus albula</Emphasis> L. and the European whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> L. under conditions of technogenic water reservoir pollution

Changes of the bile acid composition were studied in bile of the vendace Coregonus albula L. and the sea whitefish Coregonus lavaretus L. under effect of sewers of an ore mining and processing plant, the main polluting agents of the sewers being heavy metals. The revealed variability of the bile acid composition indicates different species-related sensitivity to the studied pollutants as well as a lower resistance of males as compared with females to this type of pollution. Mechanisms of effects of industrial sewers on the bile formation processes and a possibility of using parameters of the steroid lipid metabolism at evaluation of the state of aquatic ecosystems are discussed.     

Effect of Competition and Treatment with Inhibitor of Ethylene Perception on Growth and Hormone Content of Lettuce Plants

We elucidated the effect of increased planting density (single and grouped competing plants) on concentrations of auxin, abscisic acid, and cytokinins in normal lettuce plants and in those with ethylene perception inhibited by 1-methylcyclopropene (1-MCP). An attempt was made to relate the changes in hormone concentration induced by competition and inhibition of ethylene sensitivity to growth responses of lettuce planting. The results showed changes in concentrations of auxins, cytokinins, and ABA in the response of lettuce to crowding. Accumulation of ABA in shoots was likely to contribute to inhibition of transpiration of the plants grown in the presence of neighbors. This assumption was supported by the results of application of an inhibitor of ABA synthesis (fluridone and carotenoid biosynthesis herbicide) resulting in increased transpiration of grouped, but not single plants. Increased planting density led to the decline in root auxins paralleled by inhibition of root growth. This effect was likely to be due to decreased auxin transport to the roots from the shoots suggested by accumulation of auxins in the shoots and inhibition of root growth by application of the auxin transport inhibitor [N-(1-naphtyl)phtalamic acid (NPA)]. Importance of the changes in hormone concentrations was confirmed by data showing that disturbance of auxin and cytokinin distribution detected in MCP-treated plants was accompanied by corresponding modification of the growth response.

     

Crystallization and preliminary crystallographic analysis of ribosomal protein S8 from Thermus thermophilus

Crystals have been obtained for recombinant ribosomal protein S8 from Thermus thermophilus produced by Escherichia coli. The protein crystals have been grown in 40 mM potassium phosphate buffer (pH 6.0) in hanging drops equilibrated against saturated ammonium sulfate (unbuffered) with 2-methyl-2,4-pentandiol (v/v). The crystals belong to the space group P4₁₍₃₎2₁2 with cell parameters a= b= 67.65 Å, c= 171.12 Å. They diffract x-rays to 2.9 Å resolution. © 1997 Wiley-Liss, Inc.     

Human Immunoglobulin Light Chains λ Form Amyloid Fibrils and Granular Aggregates in Solution

Myeloma nephropathy is a disorder characterized by deposition of monoclonal immunoglobulin light chains in the kidneys. The chains deposited form either amyloid fibrils or granular (amorphous) aggregates. Distinct molecular mechanisms leading to the formation of different aggregate types in kidney of patients with multiple myeloma are poorly understood. Here we describe the self-association kinetics of human monoclonal immunoglobulin light chains lambda (GRY) isolated from urine of a patient with multiple myeloma. Under physiological conditions, the isolated light chain exists predominantly in a form of covalent dimer with apparent molecular mass of 50.1 kD. Spectral probe binding, analytical gel filtration, Western blot analysis, and electron microscopy indicate that GRY dimer aggregation occurs via two different pathways producing either amyloid fibrils or amorphous aggregates depending on microenvironment. Incubation of GRY (25 microM) for 4-14 days at 37 degrees C in phosphate buffered saline (PBS), pH 7.0, or in PBS containing urea (0.8 M), pH 6.5, leads to amyloid fibril formation. Under electron microscopy, the fibrils show unbranched thread-like structures, approximately 60-80 x 1000 A in size, which can bind thioflavin T and Congo Red. GRY maintained in acetate buffer, pH 3.5, forms granular aggregates. The structure of GRY oligomers formed during the early stage of amyloid fibril formation (1-4 days) has been examined by means of protein cross-linking with homobifunctional reagents. These oligomers are predominantly trimers and tetramers.     

C-heterochromatin during synapsis and recombination in grey cockroach Nauphoeta cinerea spermatogenesis

The behavior of large, distal, C-heterochromatic blocks in the spermatogenesis of the grey cockroach Nauphoeta cinerea was investigated by light and electron microscopy. In early meiotic prophase I, heterochromatic blocks of some autosomes are involved in the nonhomologous association and form a chromocenter. Fluorescent in situ hybridization (FISH) with a ribosomal DNA (rDNA) probe revealed the signal on only two pairs of middle chromosomes not engaged in the chromocenter formation; therefore, ectopic conjugation was not caused by the formation of a nucleolus. Analysis showed that chromocentric heterochromatin does not participate (functionally or spatially) in basic meiotic events. Heterochromatin does not participate in the formation of a bouquet, initiation of homologous synapsis, or recombination events. The chromocenter disintegrates at the end of the pachytene when synapsis is totally completed. Heterochromatin polymorphism results in asymmetric synaptonemal complexes (SCs) with different degrees of synaptic adjustment. The axis of the sex univalent (male sex determination is XO) is split in various sites, regardless of heterochromatin localization.