Effect of hydrocarbon concentration of pasture production (<i>Brachiaria humidicola</i>) in Texistepec,Veracruz

In this study, the relationship between the concentration of extra-heavy crude petroleum in a clayey material and the toxicity, field capacity, temperature, and growth of a tropical forage grass (Brachiara humidicola) was determined empirically. For this type of petroleum the acute toxicity (Microtox^®) was slight (CE₅₀ = 63200 - 76400 mg/kg) even at high hydrocarbon concentrations (29279 mg/kg). Nonetheless, serious impacts were encountered in terms of an increase in soil temperature (+ 1.3 °C), reduction in field capacity (-10.7%) and reduction in aerial biomass (-97%). The relationship between hydrocarbon concentration and biomass resulted in a typical dose-response curve (r = 0.99), where a concentration of 2626 mg/kg of hydrocarbons corresponds to a maintenance of 90% biomass. Furthermore, during the duration of this study (one year) the biodegradation was proportional to the pasture biomass production (r = 0.997) indicating a synergistic relationship between the petroleum biodegrading microorganisms in the rhizosphere and the pasture.     

High-level expression of the Endo-beta-N-acetylglucosaminidase F2 gene in E.coli: one step purification to homogeneity

The Endo F2gene was overexpressed in E.coli as a fusion protein joined to the maltose-binding protein. MBP-Endo F2was found in a highly enriched state as insoluble, inactive inclusion bodies. Extraction of the inclusion bodies with 20% acetic acid followed by exhaustive dialysis rendered the fusion protein active and soluble. MBP-Endo F2was digested with Factor Xaand purified on Q-Sepharose. The enzyme was homogeneous by SDS-PAGE, and appeared as a single symmetrical peak on HPLC. Analysis of the amino-terminus demonstrated conclusively that recombinant Endo F2was homogeneous and identical to the native enzyme.      

Evidence for the presence of β-lactamase inStreptomyces glaucescens and its inhibition by sodium clavulanate

Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis.     

Trichopodiella faurei n. sp. (Ciliophora,Phyllopharyngea, Cyrtophoria): Morphological Description and Phylogenetic Analyses Based on SSU rRNA and Group I Intron Sequences

ABSTRACT. A new marine cyrtophorian ciliate Trichopodiella faurei n. sp., which belongs to the order Dysteriida, family Hartmannulidae, was investigated at the morphological and molecular levels. A combination of morphological features of the organism including the oval body shape, 2–3 contractile vacuoles, 22–28 nematodesmal rods in the cytopharyngeal basket, and 31–39 somatic kineties, distinguishes it from all other known congeners. In reconstructed small subunit (SSU) rRNA phylogenies, T. faurei groups with Isochona, a representative genus of the subclass Chonotrichia. The similarity of the infraciliature between hartmannulids and several chonotrichian examples also suggests that these taxa should be closely related. A new S943 intron belonging to group IC1 was identified in the SSU rRNA gene of this species. This intron is phylogenetically related to the S891 introns previously found in the suctorians Acineta sp. and Tokophrya lemnarum, and their internal guide sequences share four nucleotides, indicating that these introns were vertically inherited from a common phyllopharyngean ancestor and that reverse splicing might have been involved in the transposition.     

Epidemiological Characteristics of Strongyloidiasis in Inhabitants of Indigenous Communities in Borneo Island,Malaysia

Epidemiological study on strongyloidiasis in humans is currently lacking in Malaysia. Thus, a cross-sectional study was carried out to determine the prevalence of Strongyloides stercoralis infection among the inhabitants of longhouse indigenous communities in Sarawak. A single stool and blood sample were collected from each participant and subjected to microscopy, serological and molecular techniques. Five species of intestinal parasites were identified by stool microscopy. None of the stool samples were positive for S. stercoralis. However, 11% of 236 serum samples were seropositive for strongyloidiasis. Further confirmation using molecular technique on stool samples of the seropositive individuals successfully amplified 5 samples, suggesting current active infections. The prevalence was significantly higher in adult males and tended to increase with age. S. stercoralis should no longer be neglected in any intestinal parasitic survey. Combination of more than 1 diagnostic technique is necessary to increase the likelihood of estimating the ‘true’ prevalence of S. stercoralis.     

Nucleosome formation with the testis-specific histone H3 variant, H3t, by human nucleosome assembly proteins in vitro

Five non-allelic histone H3 variants, H3.1, H3.2, H3.3, H3t and CENP-A, have been identified in mammals. H3t is robustly expressed in the testis, and thus was assigned as the testis-specific H3 variant. However, recent proteomics and tissue-specific RT-PCR experiments revealed a small amount of H3t expression in somatic cells. In the present study, we purified human H3t as a recombinant protein, and showed that H3t/H4 forms nucleosomes with H2A/H2B by the salt-dialysis method, like the conventional H3.1/H4. We found that H3t/H4 is not efficiently incorporated into the nucleosome by human Nap1 (hNap1), due to its defective H3t/H4 deposition on DNA. In contrast, human Nap2 (hNap2), a paralog of hNap1, promotes nucleosome assembly with H3t/H4. Mutational analyses revealed that the Ala111 residue, which is conserved among H3.1, H3.2 and H3.3, but not in H3t, is the essential residue for the hNap1-mediated nucleosome assembly. These results suggest that H3t may be incorporated into chromatin by a specific chaperone-mediated pathway.     

Morphology and Small Subunit rDNA Gene Sequence of Pseudoamphisiella quadrinucleata n. sp. (Ciliophora,Urostylida) from the South China Sea

ABSTRACT. The urosylid genus Pseudoamphisiella was established by Song (1996) with hitherto only two known congeners. In the present work, the morphology and infraciliature of a new member, Pseudoamphisiella quadrinucleata n. sp., a form with conspicuous alveolar layer and four macronuclear nodules isolated from the coastal waters both near Hong Kong and near Guangzhou, South China were investigated using living observation and protargol silver impregnation methods. Pseudoamphisiella quadrinucleata differs from other two known forms mainly by the number of macronuclear nodules: constantly four vs. two in Pseudoamphisiella alveolata and 24–57 in Pseudoamphisiella lacazei. To support this, the sequence of the small subunit rDNA of P. quadrinucleata n. sp. showed 14 and 74 nucleotides in comparison with that of the two known congeners, respectively, which hence firmly supports the validity of the new species.     

Characterization of the tissue-specific expression of phenylalanine ammonia-lyase gene promoter from loblolly pine (<Emphasis Type="Italic">Pinus taeda</Emphasis>) in <Emphasis Type="Italic">Nicotiana tabacum</Emphasis>

We isolated the 5′ flanking region of a gene for phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) from Pinus taeda, PtaPAL. To investigate the tissue-specific expression of the PtaPAL promoter, histochemical assay of GUS activity was performed using the transgenic tobacco expressing the PtaPAL promoter-GUS. The region of −897 to −420 in PtaPAL promoter showed high activities in the secondary xylem and response to bending stress. To characterize the cis-regulatory functions of the promoters for enzymes in phenylpropanoid biosynthesis, we examined the activity of chimeric promoters of PtaPAL and a 4-coumarate CoA ligase, Pta4CLα. The chimeric promoter showed similar activity as the Pta4CLα promoter. Electrophoretic mobility shift assays implicated −897 to –674 of PtaPAL promoter containing cis-elements of the expression in xylem of Pinus taeda. The results suggested that AC elements of PtaPAL have multiple functions in the expression under the various developmental stages and stress conditions in the transgenic tobacco. The nucleotide sequence data reported will appear in the EMBL, GenBank, and DDBJ Nucleotide Sequence Databases under the accession number AB449103 (PtaPAL promoter sequence).