Characterization of a maltose transport system in Clostridium acetobutylicum ATCC 824

The utilization of maltose by Clostridium acetobutylicum ATCC 824 was investigated. Glucose was used preferentially to maltose, when both substrates were present in the medium. Maltose phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS) activity was detected in extracts prepared from cultures grown on maltose, but not glucose or sucrose, as the sole carbon source. Extract fractionation and PTS reconstitution experiments revealed that the specificity for maltose is contained entirely within the membrane in this organism. A putative gene system for the maltose PTS was identified (from the C. acetobutylicum ATCC 824 genome sequence), encoding an enzyme II^Mal and a maltose 6-phosphate hydrolase. Journal of Industrial Microbiology & Biotechnology (2001) 27, 298–306. Received 12 September 2000/ Accepted in revised form 30 November 2000     

The effect of the x-ray irradiation of rats on the NAD-pyrophosphorylase and poly(ADP-ribose)polymerase activities of brain nuclei and on the NAD content in nerve tissue

A study was made of the influence of X-irradiation of rats with various doses on NAD-pyrophosphorylase and poly(ADP-ribose) polymerase activity of brain nuclei. It was shown that X-radiation was ineffective with regard to NAD-pyrophosphorylase activity of nuclei and increased their poly(ADP-ribose) polymerase activity. Stimulation of poly(ADP-ribose) polymerase activity of nuclei was a function of radiation dose and correlated with the decrease in the NAD content of nervous tissue. It was found that mainly nonhistone proteins were ADP-ribosylated in nuclei of both irradiated and nonirradiated rats.     

Pectic homogalacturonan masks abundant sets of xyloglucan epitopes in plant cell walls

Background  

Molecular probes are required to detect cell wall polymers in-situ to aid understanding of their cell biology and several studies have shown that cell wall epitopes have restricted occurrences across sections of plant organs indicating that cell wall structure is highly developmentally regulated. Xyloglucan is the major hemicellulose or cross-linking glycan of the primary cell walls of dicotyledons although little is known of its occurrence or functions in relation to cell development and cell wall microstructure.     

Isolation and certain properties of minor protein P55 inhibiting myosin and actinomyosin ATPase activity

A method of minor protein P55 isolation from extract of soluble proteins of A-zone of the sarcomere from rabbit skeletal muscle is described. It is shown that this protein inhibits Ca2+-ATPase of myosin and Mg2+-ATPase of reconstructed actomyosin, but it does not affect superprecipitation of actomyosin. The molecular weight which is determined by mobility and its polypeptide chain polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate is about 35 000 dalton.     

Evidence that the phytochrome gene family in black cottonwood has one PHYA locus and two PHYB loci but lacks members of the PHYC/F and PHYE subfamilies

The phytochrome photoreceptors play important roles in the photoperiodic control of vegetative bud set, growth cessation, dormancy induction, and cold-hardiness in trees. Interestingly, ecotypic differences in photoperiodic responses are observed in many temperate- zone tree species. Northern and southern ecotypes of black cottonwood (Populus trichocarpa Torr. & Gray), for example, exhibit marked differences in the timing of short-day-induced bud set and growth cessation, and these responses are controlled by phytochrome. Therefore, as a first step toward determining the molecular genetic basis of photoperiodic ecotypes in trees, we characterized the phytochrome gene (PHY) family in black cottonwood. We recovered fragments of one PHYA and two PHYB using PCR-based cloning and by screening a genomic library. Results from Southern analyses confirmed that black cottonwood has one PHYA locus and two PHYB loci, which we arbitrarily designated PHYB1 and PHYB2. Phylogenetic analyses which included PHY from black cottonwood, Arabidopsis thaliana and tomato (Solanum lycopersicum) suggest that the PHYB/D duplications in these species occurred independently. When Southern blots were probed with PHYC, PHYE, and PHYE heterologous probes, the strongest bands that we detected were those of black cottonwood PHYA and/or PHYB. These results suggest that black cottonwood lacks members of the PHYC/F and PHYE subfamilies. Although black cottonwood could contain additional PHY that are distantly related to known angiosperm PHY, our results imply that the PHY family of black cottonwood is less complex than that of other well-characterized dicot species such as Arabidopsis and tomato. Based on Southern analyses of five black cottonwood genotypes representing three photoperiodic ecotypes, substantial polymorphism was detected for at least one of the PHYB loci but not for the PHYA locus. The novel character of the PHY family in black cottonwood, as well as the differences in polymorphism we observed between the PHYA and PHYB subfamilies, indicates that a number of fundamental macro- and microevolutionary questions remain to be answered about the PHY family in dicots.      

Ca2+-binding sites and Ca2+-ATPase activity in barley root tip cells

Summary Different cytochemical methods were employed to demonstrate the existence of Ca²⁺-binding sites (Ca²⁺-bs) at the membranes of barley root tip cells, involving addition of CaCl₂ (10 mM or 1 mM) to all aqueous solutions used for tissue processing for electron microscopy, treatment of ultrathin sections by Ca-chelating agents, enzymic digestion of ultrathin sections and modification of Wachstein-Meisel procedure for localization of Ca²⁺-dependent ATPase activity. Addition of 10 mM CaCl₂ to the fixatives and rinsing solutions causes electron-dense globules (EDG) to be formed in a variety of cells, those in cortical cells being associated mainly with the plasma membranes, in root cap cells with the plasmalemma as well as with majority of intracellular membranes. The obligatory presence of EDG at the membranes of Golgi vesicles and secretory vesicles approaching plasmalemma was revealed in the secreting root cap cells. Besides, electron opaque connecting material was found between the plasmalemma and adjacent secretory vesicle membranes. In true meristematic cells Ca-supplemented solutions induce formation of EDG localized at the ER membranes, and nuclear and plastid envelopes. In root cells of seeds germinated in the presence of 1 mM CaCl₂ electron opaque deposits were found only in local areas of plasmalemma collars around plasmodesmata neck regions, contacting the terminals of subsurface ER channels. In control speciemens (germination, fixation and washing without added CaCl₂) EDG were absent in cortical and ground meristem cells, but present in root cap cells, although their number and average size were greatly reduced.Treatment of thin sections by 10mM EGTA or EDTA led to complete removing of EDGs, electron-transparent holes replacing them. Digestion by a variety of proteolytic enzymes and by phospholipase A induced partial destruction of EDG matrices, confirming the presence of protein as well as of phospholipid membrane components. Visualization of electron-dense granular product of cytochemical Ca-ATPase reaction at the same membrane areas where EDG were located suggests that one of the Ca-binding proteins in EDG may represent Ca-ATPase.It is proposed that EDG at plant cell membranes have a certain resemblance to the Ca²⁺-bs revealed by the same method on plasma membrane of a variety of animal cells. The data obtained are discussed regarding possible regulatory roles of calcium ions in plant cells, especially in exocytotic secretion.     

Peptide conjugates of benzene and toluene metabolites in English ryegrass

Biotransformation of [1-6-¹⁴C]benzene and [1-¹⁴C]toluene in English ryegrass (Lolium perenne L.) seedlings was investigated. Vapors of these compounds were absorbed by the leaves of this plant. Benzene and toluene were oxidized, forming phenol and benzoic acid, respectively. A portion of phenol and benzoic acid was bound by low-molecular-weight peptides forming conjugates. A qualitative amino acid composition of the peptides involved in the conjugation was determined. After removing plants from the atmosphere containing [1-6-¹⁴C]benzene and [1-¹⁴C]toluene, the radioactivity of the conjugates gradually decreased. This process was accompanied by the evolution of ¹⁴CO₂, indicating the breakdown of these conjugates. Radioactive compounds thus formed were oxidized, yielding carbon dioxide. A portion of phenol and benzoic acid, along with peptide conjugation, was subjected to further oxidative transformations up to disruption of the aromatic ring. By this pathway, nonvolatile carboxylic acids, such as muconic, fumaric, succinic, malic, malonic, glycolic, and glyoxylic, were formed. Using electron microscopy, a damaging effect of benzene on the cell ultrastructure of English ryegrass leaves was shown, and this toxic effect depended on the benzene concentration.     

ADP-ribosylation intensifies cleavage of DNA loops in the nuclear matrix

Pulsed-field electrophoresis of DNA was used to demonstrate that ADP-ribosylation stimulates the cleavage of DNA loops at the sites of their anchorage to the nuclear matrix in nucleoids of human mononuclear leukocytes and rat brain neurons. ADP-ribosylation was assumed to play a role in regulating the activity of topoisomerase II in the nuclear matrix of eukaryotic cells.__________Translated from Molekulyarnaya Biologiya, Vol. 39, No. 2, 2005, pp. 317–320.Original Russian Text Copyright © 2005 by G. Zaalishvili, Tsetskladze, Margiani, Gabriadze, T. Zaalishvili.     

Plant potential for detoxification (Review)

Data on the uptake, excretion, and biodegradation of organic xenobiotics by plants are reviewed. Detoxification pathways operating in plants and their role in remediation of the biosphere are described. Structure-, concentration-, and time-dependent effects of xenobiotics on the ultrastructural organization of cells are analyzed.     

Effective complementarily-addressed photomodification of nucleic acids by oligonucleotide derivatives, containing aromatic azido groups]

Highly effective site-specific photomodification of a DNA-target was carried out with oligonucleotide reagents carrying aromatic azido groups. Oligonucleotide derivatives with a photoactive function R on the 5'-terminal phosphate and at C-5 atom of deoxyuridine were synthesized: R1NH(CH2)3NHpd(TCCACTT) and d(ULNHRCCACTT), where R1 is p-azidotetrafluorobenzoyl, R2 is 2-nitro, 5-azidobenzoyl, R3 is p-azidobenzoyl; LNH = -CH2NH-, -CH2OCH2CH2NH- or -CH2NHCOCH2CH2NH-. The prepared compounds form stable complementary complexes and effect site-specific photomodification of the target DNA. The modification of pentadecanucleotide d(TAAGTGGAGTTTGGC) with the reagents was investigated. Maximum extent of modification strongly depended on the reagent's type, the photoreagent with R1 being the most effective. Whatever the binding site was, this agent provided a 65-70% modification in all cases except LNH = -CH2NH-, when the yield was twice lower. For the reagents bearing R1 the modification sites were identified. Selective modification at the G9 residue was detected in the case of LNH = -CH2OCH2CH2NH- and when a photoactive group was linked to the terminal phosphate.