Lab-Scale Biodegradation Study of BTEX under the Unsaturated Condition and Its Effect on Soil Matric Potential

Benzene, toluene, ethylbenzene, and xylene are collectively known as BTEX which contributes to volatile environmental contaminants. This present study investigates the microbial degradation of BTEX in batch and continuous soil column experiments and its effects on soil matric potential. Batch degradation experiments were performed with different initial concentrations of BTEX using the BTEX tolerant culture isolated from petroleum-contaminated soil. In batch study, the degradation pattern for single substrate showed that xylene was degraded much faster than other compounds followed by ethylbenzene, toluene, and benzene with the highest μ_max = 0.140 h^?1 during initial substrate concentration of 100 mg L^?1. Continuous degradation experiments were performed in a soil column with an inlet concentration of BTEX of about 2000 mg L^?1 under unsaturated flow in anaerobic condition. BTEX degradation pattern was studied with time and the matric potential of the soil at different parts along the length of the column were determined at the end of the experiment. In continuous degradation study, BTEX compounds were degraded with different degradation pattern and an increase in soil matric potential was observed with an increase in depth from top to bottom in the column with applied suction head. It was found that column biodegradation contributed to 69.5% of BTEX reduction and the bacterial growth increased the soil matric potential of about 34% on an average along the column height. Therefore, this study proves that it is significant to consider soil matric potential in modeling fate and transport of BTEX in unsaturated soils.     

Occurrence of Pseudoterranova decipiens (Nematoda) in fish from the Southeastern Weddell Sea (Antarctic)

Eleven fish species from the Weddell Sea (Antarctic) were examined for infestation with anisakid nematodes. Two species of the genus Contracaecum and the sealworm Pseudoterranova decipiens were isolated from the liver and the body cavity of fish affected. Only two specimens of P. decipiens (1.4%) partly invaded the belly flaps. The following fish species were infested by P. decipiens at the given prevalences: Cygnodraco mawsoni (74.4%), Trematomus scotti (23.2%), Pagetopsis maculatus (10.0%), Cryodraco antarcticus (7.1%), Trematomus lepidorhinus (3.0%), and Dolloidraco longedorsalis (2.7%). All of these, except Trematomus scotti, are new host records. Chaenodraco wilsoni, Chionodraco myersi, Gerlachea australis, Racovitzia glacialis and T. eulepidotus were not infested. The reasons for low prevalence and intensity of infestation are seen in the difficulties of P. decipiens in completing its benthic life cycle in the Weddell Sea environment, in the absence of shallow coastal waters due to the floating shelf-ice. Cygnodraco mawsoni is a crucial intermediate host, without which completion of the parasite life cycle might not be possible. In order to clarify the taxonomical position of Antarctic Pseudoterranova, morphological comparisons with specimens of P. decipiens from the German and Norwegian coast were made using scanning electron microscopy. Results revealed no differences; hence, all specimens studied belong to the same species P. decipiens.     

Extremophile extracts and enhancement techniques show promise for the development of a live vaccine against Flavobacterium columnare

The effects of temperature, ionic strength, and new cryopreservatives derived from polar ice bacteria were investigated to help accelerate the development of economical, live attenuated vaccines for aquaculture. Extracts of the extremophile Gelidibacter algens functioned very well as part of a lyophilization cryoprotectant formulation in a 15-week storage trial. The bacterial extract and trehalose additives resulted in significantly higher colony counts of columnaris bacteria (Flavobacterium columnare) compared to nonfat milk or physiological saline at all time points measured. The bacterial extract combined with trehalose appeared to enhance the relative efficiency of recovery and growth potential of columnaris in flask culture compared to saline, nonfat milk, or trehalose-only controls. Pre-lyophilization temperature treatments significantly affected F. columnare survival following rehydration. A 30-min exposure at 0 °C resulted in a 10-fold increase in bacterial survival following rehydration compared to mid-range temperature treatments. The brief 30 and 35 °C pre-lyophilization exposures appeared to be detrimental to the rehydration survival of the bacteria. The survival of F. columnare through the lyophilization process was also strongly affected by changes in ionic strength of the bacterial suspension. Changes in rehydration constituents were also found to be important in promoting increased survival and growth. As the sodium chloride concentration increased, the viability of rehydrated F. columnare decreased.     

Two discrete DNA replication intermediates are formed in melphalan-treated cells

Regulated and nonregulated phosphorylases were found to catalyze in a slow, orthophosphate dependent reaction the direct transfer of the glucosyl residue from α-D-glucosyl fluoride to an oligosaccharide primer. The enzyme catalyzed formation of the glucosyl residue requires stereospecific protonation of α-D-glucosyl fluoride by a Brønstedt acid. The results are interpreted by a mechanism whereby phosphate acts as a proton shuttle and the cofactor pyridoxal 5′-phosphate is required to promote the acid-base function of phosphate.     

Growth cone guidance by substrate-bound laminin pathways is correlated with neuron-to-pathway adhesivity

Substrate-bound laminin pathways prepared by the method of Hammarback et al. [J.A. Hammarback, S.L. Palm, L.T. Furcht, and P.C. Letourneau (1985). J. Neurosci. Res. 13, 213-220] guided peripheral nervous system neurites (dissociated dorsal root ganglia and sympathetic ganglia) and central nervous system neurites (dissociated spinal cord and brain). Guidance of individual growth cones by 7- to 10-micron-wide laminin pathways was observed using time-lapse video microscopy. Fibronectin pathways, produced by the method used for laminin pathways, did not guide neurites. The guidance effect of laminin pathways was quantified and found to correlate with the concentration of laminin initially applied to the substratum. The concentration of laminin initially applied to the substratum also correlated with increased adhesivity of dorsal root ganglia (DRG) neurons to laminin constituting the pathways relative to uv-irradiated laminin that borders the pathways. The guidance effect of laminin pathways was blocked by anti-laminin antibodies or by laminin but not by anti-fibronectin antibodies. This study demonstrates that guidance of DRG neurites by laminin occurs at the growth cone in a manner consistent with the hypothesis of guidance by differential neuron-to-substratum adhesivity.     

Is cadmium released from metallothionein in rejected human kidneys?

Summary Concentrations of metallothionein and metals, i.e. cadmium, copper and zinc, were determined in six rejected transplanted human kidneys and one kidney prepared for transplantation. Tissue samples separated by gel chromatography showed that almost all of cadmium in tissue was in the form of firmly bound cadmium-metallothionein.     

Linear dichroism studies of binding site structures in solution: Complexes between DNA and basic arylmethane dyes

The interaction between B-form DNA and twelve cationic triaryl-methane dyes was studied with respect lo optical properties and stabilities, using linear dichroism (LD) and aqueous two-phase partition techniques. Monovalent dyes derived from crystal violet as a rule form a single strong complex (K₁ ca 10⁵ M^?1; site density per nucleotide base n₁ ca 0.1 at 0.1M ionic strength) in which the plane of the dye is at an angle of less than 50° to the local DNA helix axis. The complex with fuchsin is weaker (10⁴M^?1) but can be explained by a similar orientation. For some of the dyes (those with pseudo-C_2v symmetry) XXXre angular orientations of two molecule-fixed axes can be obtained. For the divalent methyl green a second complex appears to be formed at low ionic strength. Methyl green (and to some extent 2-thiophene green and malachite green) show exciton splitting in the LD spectrum and circular dichroism assignable to exciton coupling between transition dipoles roughly parallel to the helical strands, indicating a dye-dye interaction. Tne optical data, supported by fitting experiments with space-filling models, suggests a general structure for the binding site. The dye is not intercalated but is bound to exposed hydrophobic regions in the major groove. The ligand is in part (the charged amino groups) in contact with the phosphoribose chain but its main surface lies against the hydrophobic base-pair stack. For a diphenylmethane dye, Michler's hydrol blue, a perpendicular orientation was observed, possibly due to intercaiation.