Editing of the grapevine mitochondrial cytochrome b mRNA and molecular modeling of the protein

Cytochrome b (COB), the central catalytic subunit of ubiquinol cytochrome c reductase, is a component of the transmembrane electron transfer chain that generates proton motive force. Some plant COB mRNAs are processed by RNA editing, which changes the gene coding sequence. This report presents the sequences of the grapevine (Vitis vinifera L.) mitochondrial gene for apocytochrome b (cob), the edited mRNA and the deduced protein. Grapevine COB is 393 amino acids long and is 98% identical to homologs in rapeseed, Arabidopsis thaliana and Oenothera sp. Twenty-one C-U editing sites were identified in the grapevine cob mRNA, resulting in 20 amino acid changes. These changes increase the overall hydrophobicity of the protein and result in a more conserved protein. Molecular modeling of grapevine COB shows that residues changed by RNA editing fit the secondary structure characteristic of an integral membrane protein. This is the first complete mitochondrial gene reported for grapevine. Novel RNA editing sites were identified in grapevine cob, which have not been previously reported for other plants.     

Elevation of superoxide dismutase in Halobacterium halobium by heat shock.

Exposure of Halobacterium halobium to 50 degrees C for 2.5 h in an aerobic environment resulted in a greater than twofold increase in the activity of the manganese-containing superoxide dismutase. Nondenaturing polyacrylamide gels stained for enzymatic activity did not reveal any additional isozymes of superoxide dismutase induced by the heat shock. The maximal effect was observed at 50 degrees C, and the elevated levels of activity remained constant during 5 h of recovery at 40 degrees C. The induction of enzymatic activity was sensitive to protein synthesis inhibitors. The results are discussed relative to heat shock and stress-related proteins as well as alterations in metabolism brought about by elevated temperatures.     

Characterization of Rhizobacteria Associated with Weed Seedlings

Rhizobacteria were isolated from seedlings of seven economically important weeds and characterized for potential phytopathogenicity, effects on seedling growth, and antibiosis to assess the possibility of developing deleterious rhizobacteria as biological control agents. The abundance and composition of rhizobacteria varied among the different weed species. For example, fluorescent pseudomonads represented from 11 to 42% of the total rhizobacterial populations from jimsonweed and lambsquarters, respectively. Other bacteria frequently isolated were nonfluorescent pseudomonads, Erwinia herbicola, Alcaligenes spp., and Flavobacterium spp. Only 18% of all isolates were potentially phytopathogenic, based on an Escherichia coli indicator bioassay. However, the proportion of isolates that inhibited growth in seedling assays ranged from 35 to 65% depending on the weed host. Antibiosis was most prevalent among isolates of fluorescent Pseudomonas spp., the activity of which was due to siderophore production in over 75% of these isolates. Overall, rhizobacterial isolates exhibited a complex array of properties that were inconsistent with accepted definitions for plant growth-promoting and deleterious rhizobacteria. It is suggested that for development of effective biological control agents for weed control, deleterious rhizobacteria must be screened directly on host seedlings and must possess several properties including high colonizing ability, specific phytotoxin production, and resistance or tolerance to antibiotics produced by other rhizosphere microorganisms, and they must either synthesize or utilize other bacterial siderophores.     

Quantitative analysis of brain microstructure following mild blunt and blast trauma

We induced mild blunt and blast injuries in rats using a custom-built device and utilized in-house diffusion tensor imaging (DTI) software to reconstruct 3-D fiber tracts in brains before and after injury (1, 4, and 7 days). DTI measures such as fiber count, fiber length, and fractional anisotropy (FA) were selected to characterize axonal integrity. In-house image analysis software also showed changes in parameters including the area fraction (AF) and nearest neighbor distance (NND), which corresponded to variations in the microstructure of Hematoxylin and Eosin (H&E) brain sections. Both blunt and blast injuries produced lower fiber counts, but neither injury case significantly changed the fiber length. Compared to controls, blunt injury produced a lower FA, which may correspond to an early onset of diffuse axonal injury (DAI). However, blast injury generated a higher FA compared to controls. This increase in FA has been linked previously to various phenomena including edema, neuroplasticity, and even recovery. Subsequent image analysis revealed that both blunt and blast injuries produced a significantly higher AF and significantly lower NND, which correlated to voids formed by the reduced fluid retention within injured axons. In conclusion, DTI can detect subtle pathophysiological changes in axonal fiber structure after mild blunt and blast trauma. Our injury model and DTI method provide a practical basis for studying mild traumatic brain injury (mTBI) in a controllable manner and for tracking injury progression. Knowledge gained from our approach could lead to enhanced mTBI diagnoses, biofidelic constitutive brain models, and specialized pharmaceutical treatments.     

Enhancing ethanol fermentability of an artificial acid hydrolyzate with anion exchange resin treatment

To assess the effectiveness of anion exchange resins (Dowex M43 and Dowex monosphere 66) in neutralization and detoxification of an acid hydrolyzate solution, a fermentation medium containing inhibitors was inoculated with Saccharomyces cerevisiae. When treated with resins at a 1:1 ratio (vol:wt) for up to 20 min, 55-67% of furan and more than 95% of phenolic compounds were removed. Ethanol fermentation activity in resin-treated fermentation medium was the same as the control. There was 21-43% of the total sugar loss after one resin treatment, depending on the sugar concentration. Additional treatments increased sugar retention rate to 95%.     

Effect of culture conditions on the production of ligninolytic enzymes by white rot fungi Phanerochaete chrysosporium (ATCC 20696) and separation of its lignin peroxidase

The present work was carried out to determine the optimum culture conditions of Phanerochaete chrysosporium (ATCC 20696) for maximizing ligninolytic enzyme production. Additionally, separation of its lignin peroxidase was conducted. After experiments, an optimized culture medium/condition was constructed (per liter of Kirk’s medium): dextrose 10 g, ammonium tartrate 0.11 g, Tween-80 0.5 g, MnSO₄ 7 mg, and veratryl alcohol 0.3 g in 10 mM acetic acid buffer pH 4.5. Under the optimized experimental condition, both lignin peroxidase (LiP) and manganese peroxidase (MnP) were detected and reach the highest yield at 30°C on the 8th day culture. Salt precipitation methods was used in the extraction and purification processes. Results show that salt precipitation with 60% (NH₄)₂SO₄ yielded the best result, especially toward LiP. Enzyme separation was conducted and two fractions with LiP activity. LiP1 and LiP2 were produced using three columns sequentially: desalting column, Q FF ion exchange column and Sepharyl S-300 HR gel filtration. LiP1 and LiP2 had been purified by 9.6- and 7.6-fold with a yield of 22.9% and 18.6%, respectively. According to the data of sodium dodecyl sulfate polyacrilamide gel electrophoresis (SDS-PAGE), the molecular weights of the enzymes are 38 kDa and 40 kDa, respectively.     

Influence of food dispersion on feeding activity and social interactions in captive Lophocebus albigena and Cercocebus torquatus torquatus

We analysed the impact of the distribution of food items on feeding activity and social interactions in captive red-capped and grey-cheeked mangabeys. Three different feeding situations were presented: food items were either placed in a single heap or dispersed in several smaller heaps on the ground or in space. Social interactions were estimated by the frequency of positive, as well as of negative social interactions and by the structure of visual social attention. Feeding activity was estimated by proximity to food and feeding frequency. When food items were presented in single heaps, the adult males monopolized the food and monitoring of conspecifics increased. Social interactions and social gazes decreased in numbers when food items were dispersed in 3D. Gazes were directed more frequently towards the adult males when food items were presented in a single heap. Juveniles and some nonreproductive adult monkeys were the most affected by food competition situations. Inter-group variations, within a given species, of the behavioural responses observed in relation to the distribution of food items were evidenced. This suggests that social context, i.e., individual histories and relationship between group members, plays an important part in the expression of the activities of each member in a group.     

Effect of cuticular waxes compounds from table grapes on growth,germination and gene expression in <Emphasis Type="Italic">Botrytis cinerea</Emphasis>

Botrytis cinerea attacks a broad range of host causing significant economic losses in the worldwide fruit export industry. Hitherto, many studies have focused on the penetration mechanisms used by this phytopathogen, but little is known about the early stages of infection, especially those such as adhesion and germination. The aim of this work was to evaluate the effect of cuticular waxes compounds from table grapes on growth, germination and gene expression of B. cinerea. To accomplish this, growth was analyzed using as substrate n-alkanes extracted from waxes of fresh fruit (table grapes, blueberries and apricots). Subsequently, the main compounds of table grape waxes, oleanolic acid (OA) and n-fatty alcohols, were mixed to generate a matrix on which conidia of B. cinerea were added to assess their effect on germination and expression of bctub, bchtr and bchex genes. B. cinerea B05.10, isolated from grapes, increased its growth on a matrix composed by table grapes n-alkanes in comparison to a matrix made with n-alkanes from apricot or blueberries. Moreover, at 2.5 h, B05.10 germination increased 17 and 33 % in presence of n-alkanes from table grape, in comparison to conditions without alkanes or with blueberries alkanes, respectively. Finally, expression of bchtr and bchex showed a significant increase during the first hour after contact with n-fatty alcohols and OA. In conclusion, B. cinerea displays selectivity towards certain compounds found in host waxes, mainly n-fatty alcohols, which could be a good candidate to control this phytopathogen in early stages of infection.