Model for prediction of immobilizedAcetobacter cell number in calcium alginate gel droplets

The geometry of calcium alginate gel spheres is studied by fractal interpretation for prediction of number of cells to be immobilized. For alginate concentrations from 1 to 5% the simulated results are of 6.65×10⁸, 1.44×10⁸ and 5.27×10⁷ N cell mL⁻¹ for respectively 1.5, 2.5 and 3.5 mm gel sphere diameters. Simulated data are compared with those resulting from literature and particularly with experimental trials where from 10⁷ to 10⁸ N cell mL⁻¹, in 2% alginate beads with a diameter of 1.5 mm, is able to fulfil mechanical and swelling characteristics of alginate gel beads besides to supply good oxygenation.     

Efficacy of the alcohol use disorders identification test as a screening tool for hazardous alcohol intake and related disorders in primary care: a validity study.

OBJECTIVE: To determine the properties of the alcohol use disorders identification test in screening primary care attenders for alcohol problems. DESIGN: A validity study among consecutive primary care attenders aged 18-65 years. Every third subject completed the alcohol use disorders identification test (a 10 item self report questionnaire on alcohol intake and related problems) and was interviewed by an investigator with the composite international diagnostic interview alcohol use module (a standardised interview for the independent assessment of alcohol intake and related disorders). SETTING: 10 primary care clinics in Verona, north eastern Italy. PATIENTS: 500 subjects were approached and 482 (96.4%) completed evaluation. RESULTS: When the alcohol use disorders identification test was used to detect subjects with alcohol problems the area under the receiver operating characteristic curve was 0.95. The cut off score of 5 was associated with a sensitivity of 0.84, a specificity of 0.90, and a positive predictive value of 0.60. The screening ability of the total score derived from summing the responses to the five items minimising the probability of misclassification between subjects with and without alcohol problems provided an area under the receiver operating characteristic curve of 0.93. A score of 5 or more on the five items was associated with a sensitivity of 0.79, a specificity of 0.95, and a positive predictive value of 0.73. CONCLUSIONS: The alcohol use disorders identification test performs well in detecting subjects with formal alcohol disorders and those with hazardous alcohol intake. Using five of the 10 items on the questionnaire gives reasonable accuracy, and these are recommended as questions of choice to screen patients for alcohol problems.     

Effects of water level fluctuations on phytoplankton in a river-floodplain lake system (Paraná River,Argentina)

Several aspects of community organization wereanalyzed comparatively in a small side-arm of theParaná River (Correntoso) and a shallowfloodplain lake (El Tigre) (31° 41 S and60° 42 W), in relation to the hydrology of thesystem. Taxonomic and morphological composition inthe river differed from that in the lake: the riverhad lower species richness (151 vs 218),different contributions of some Classes to totalspecies number (higher Cyano-, Zygo- andDiatomophyceae vs higher Chlorophyceae), anddiffent proportions of nannoplanktonic algae (67.5%vs 80.7%) and netplanktonic filamentousspecies (18.2% vs 4.2%). Phytoplanktonbiomass, higher in the lake than in the river due tothe retention time, was mostly dominated bynannoplankton and netplankton. Loticphytoplankton was dominated by typical fluvialspecies of Diatomophyceae (R-strategists). Riverconditions seem to maintain a subclimacticcommunity, which was little impacted by the flushingof populations from floodplain lakes. Water levelwas the main factor controlling phytoplanktonbiomass, species diversity (H), evenness (E) andcommunity change rate () in the river. Inthe lake, phytoplankton had an autogenicsuccessional sequence during the isolation phase (C-to S-strategists) and other responses todisturbance, mainly during the flood(R-strategists). Frequent changes in phytoplanktoncomposition, biomass, H, E and , revealed aenvironmental instability in the lake, which may beexplained by interactions of external factors(hydrology and climatology) and those of internalorigin, such as nutrients and grazing.     

Evidence for two possible glnB-type genes in Herbaspirillum seropedicae.

Two glnB-like genes have been isolated from Herbaspirillum seropedicae by complementation of the Klebsiella pneumoniae glnB502 mutant for growth on nitrate. One of these glnB-like genes has been sequenced and shows strong identity with GlnB proteins derived from other organisms. A Tn5-20 mutation of this glnB was Nif negative.     

Magnetophoretic induction of curvature in coleoptiles and hypocotyls

Coleoptiles of barley (Hordeum vulgare) were positioned in a high gradient magnetic field (HGMF, dynamic factor gradient of H(2)/2 of 10(9)-10(10) Oe2 cm-1), generated by a ferromagnetic wedge in a uniform magnetic field and rotated on a 1 rpm clinostat. After 4 h 90% of coleoptiles had curved toward the HGMF. The cells affected by HGMF showed clear intracellular displacement of amyloplasts. Coleoptiles in a magnetic field next to a non-ferromagnetic wedge showed no preferential curvature. The small size of the area of nonuniformity of the HGMF allowed mapping of the sensitivity of the coleoptiles by varying the initial position of the wedge relative to the coleoptile apex. When the ferromagnetic wedge was placed 1 mm below the coleoptile tip only 58% of the coleoptiles curved toward the wedge indicating that the cells most sensitive to intracellular displacement of amyloplasts and thus gravity sensing are confined to the top 1 mm portion of barley coleoptiles. Similar experiments with tomato hypocotyls (Lycopersicum esculentum) also resulted in curvature toward the HGMF. The data strongly support the amyloplast-based gravity-sensing system in higher plants and the usefulness of HGMF to substitute gravity in shoots.     

Induction of neuronal type nitric oxide synthase in skeletal muscle by chronic electrical stimulation in vivo

Reiser, Peter J., William O. Kline, and Pal L. Vaghy.Induction of neuronal type nitric oxide synthase in skeletal muscle by chronic electrical stimulation in vivo. J. Appl. Physiol. 82(4): 1250-1255, 1997.Fast-twitch skeletal muscles contain more neuronal-type nitricoxide synthase (nNOS) than slow-twitch muscles because nNOS is presentonly in fast (type II) muscle fibers. Chronic in vivo electricalstimulation of tibialis anterior and extensor digitorum longus musclesof rabbits was used as a method of inducing fast-to-slow fiber typetransformation. We have studied whether an increase in musclecontractile activity induced by electrical stimulation alters nNOSexpression, and if so, whether the nNOS expression decreases to thelevels present in slow muscles. Changes in the expression of myosinheavy chain isoforms and maximum velocity of shortening of skinnedfibers indicated characteristic fast-to-slow fiber type transformationafter 3 wk of stimulation. At the same time, activity of NOS doubled inthe stimulated muscles, and this correlated with an increase in theexpression of nNOS shown by immunoblot analysis. These data suggestthat nNOS expression in skeletal muscle is regulated by muscle activityand that this regulation does not necessarily follow the fast-twitchand slow-twitch pattern during the dynamic phase of phenotypetransformation.

     

Quantification of Fungal Hyphae in Leaves of Deciduous Trees by Automated Image Analysis

An optical method to quantify the fungal hyphae within decomposing leaves of deciduous trees was developed. The plant matrix was partially destroyed under hydrolytic conditions, and fungal hyphae and cellulose residues within the leaves were stained with Calcofluor M2R. Cellulose residues were subsequently depolymerized by cellulase, and fungal hyphae were separated from the remaining plant matrix with a pressurized air-water mixture. An image analysis program to quantify the fungal hyphae was written. The program included the recognition of fungal hyphae, the elimination of stomata from the images, and the measuring of lengths of fungal hyphae. The optical method was verified by a chemical method relying on glucosamine as an indicator of fungal biomass. The fungal biomass in leaves of Fagus silvatica and Quercus petraea at early states of decomposition was 0.2 to 0.4% of the leaf weight. The biomass reached a maximum within 2 to 4 weeks (optical method, 0.5 to 0.7%; chemical method, 1 to 1.4% of the initial leaf weight) and decreased thereafter.     

Imazalil enhances the shoot-inducing effect of benzyladenine in Spathiphyllum floribundum Schott

In Spathiphyllum floribundum Petite Schott shoot induction by benzyladenine (BA) was enhanced dramatically by adding the imidazole fungicide imazalil to the medium. As the concentration of imazalil increased, the number of shoots increased, and finally their size was reduced to a small meristematic dome. An average of 127 shoots/ expiant developed when 2.5 mg/L BA was combined with 16 mg/L imazalil. Doubling the BA concentration had no significant effect on shoot induction. Imazalil did not affect the root-inhibiting effect of BA. When imazalil was applied without BA, the number of roots and total root length/plant were reduced, but no new shoots developed.Abbreviations GA gibberellic acid - BA benzyladenine - [9G]BA 9--d-glucopyranosylbenzyladenine - [9R]BA 9--d-ribofuranosylbenzyladenine.     

Mycoflora and aflatoxin production in pigeon pea stored in jute sacks and iron bins

The mycoflora, moisture content and aflatoxin contamination of pigeon pea (Cajanus cajan (L.) Millisp) stored in jute sacks and iron bins were determined at monthly intervals for a year. The predominant fungi on freshly harvested seeds wereAlternaria spp.,Botryodiplodia theobromae, Fusarium spp. andPhoma spp. These fungi gradually disappeared from stored seeds with time and by 5–6 months, most were not isolated. The fungi that succeeded the initially dominant ones were mainly members of the generaAspergillus, Penicillium andRhizopus. Population of these fungi increased up to the end of one year storage. Higher incidence of mycoflora andAspergillus flavus were recorded in jute-sack samples throughout the storage period. The moisture content of stored seeds was found to fluctuate with the prevailing weather condition, being low during the dry season and slightly high during the wet season. The stored seeds were free of aflatoxins for 3 and 5 months in jute sacks and iron bins respectively. The level of aflatoxins detected in jute-sack storage system was considerably higher than that occurring in the iron bin system. Of 196 isolates ofA. flavus screened, 48% were toxigenic in liquid culture (54% from jute sacks and 41% from iron bins).