Comparison of vegetative anatomy of piperales. I. Juvenile xylem of twigs

Medullary bundles of Piperaceae resemble those of Ranunculaceae. The nature of tracheary elements of primary xylem suggests that Houttuynia cordata (Saururaceae), Piper cubeba (Piperaceae) and Chloranthus officinalis (Chloranthaceae) are of lower evolutionary status than others. Among these three, P. cubeba shows stratification of secondary xylem, a specialized character. Lateral wall of metaxylem tracheary elements and distribution of bundles of Peperomia, suggest their primitive status and distinctness, supporting separation of "Peperomiacea:" (of NOVAK). Piper cubeba, Houttuynia and Chloranthus bear one important Ranunculaceous character: scalariform perforation in primary vessels. Primitive species of Peperomia carry probably another Ranunculaceous character, i.e., many circles of medullary bundles. Shape and pattern of vascular bundles of Piper cubeba, Houttuynia and Chloranthus are similar. Other species of Piper show modifications. Peperomia represents another distinct pattern.     

Ultrastructural examination of the lipopolysaccharides of Pseudomonas aeruginosa strains and their isogenic rough mutants by freeze-substitution.

The majority of Pseudomonas aeruginosa strains synthesize two antigenically distinct types of lipopolysaccharide (LPS), namely, a serotype-specific B-band LPS and a common antigen A-band LPS. A-band LPS consists of uncharged poly-D-rhamnan, which does not bind uranyl ions and is difficult to stain for electron microscopy; the highly charged B-band LPS is more easily visualized. We selected two wild-type strains, PAO1 (serotype O5) and IATS O6 (serotype O6), generated isogenic mutants from them, and examined the distribution of LPS on the surface of these organisms by freeze-substitution and electron microscopy. On PAO1 cells, which express both A-band and B-band LPSs, a 31- to 36-nm-wide fringe extending perpendicularly from the outer membrane was observed. A fine fibrous material was also observed on the surface of serotype O6 (A+ B+) cells, although this material did not form a uniform layer. When the LPS-deficient mutants, strains AK1401 (A+ B-), AK 1012 (A- B-), rd7513 (A- B-), and R5 (an IATS O6-derived rough mutant; A- B-), were examined, no extraneous material was apparent above the bilayer. However, an asymmetrical staining pattern was observed on the outer leaflet of the outer membrane of each of these mutants, presumably conforming to the anionic charge distribution of the core region of the rough LPS. In all cases, expression of the LPS types was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. When optical densitometry on electron microscopy negatives was used to analyze the outer membrane staining profiles, subtle differences in the degrees of core deficiency among rough mutants were detectable. This is the first time an electron microscopy technique has preserved the infrastructure produced in the outer membrane by its constituent macromolecules. We conclude that freeze-substitution electron microscopy is effective in the visualization of LPS morphotypes.     

Yeast cells are incapable of translating RNAs containing the poliovirus 5'' untranslated region: evidence for a translational inhibitor.

We have expressed in the yeast Saccharomyces cerevisiae a full-length poliovirus cDNA clone under the control of the GAL10 promoter to better characterize the effect of poliovirus on host cell metabolism. We find that yeast cells are unable to translate poliovirus RNA in vivo and that this inhibition is mediated through the 5' untranslated region of the viral RNA. The in vivo inhibition of translation of poliovirus RNA and P2CAT RNA (which contains the 5' untranslated region fused upstream of the bacterial chloramphenicol transferase gene) can be mimicked in vitro in yeast translation lysates. In fact, a trans-acting inhibitor present in yeast lysates can inhibit translation of either poliovirus or P2CAT RNA in HeLa cell translation lysates. In contrast, when the inhibitor is added to translations programmed with chloramphenicol acetyltransferase RNA, yeast prepro-alpha-factor RNA, or an RNA containing the internal ribosome entry site of encephalomyocarditis virus, no inhibition is seen. The inhibitory activity has been partially purified by DEAE-Sephacel chromatography. The partially purified inhibitor is heat stable, escapes phenol extraction, is resistant to proteinase K and DNase I treatment, and is sensitive to RNase A digestion, suggesting that the inhibitor is an RNA. In an in vitro translation assay, the inhibitory activity can be overcome by increasing the concentration of HeLa cell lysate but not P2CAT RNA, suggesting that the inhibitor interacts (directly or indirectly) with one or more components of the HeLa cell translational machinery rather than with the viral RNA.     

In vitro lipid peroxidation of human serum catalyzed by cupric ion: antioxidant rather than prooxidant role of ascorbate.

The dual role of ascorbate as an antioxidant and a prooxidant has been clearly documented in the literature. Ascorbate acts as an antioxidant by protecting human serum from lipid peroxidation induced by azo dye-generated free radicals. On the other hand, ascorbate is readily oxidized in the presence of transition metal ions, (especially cupric ion) and accelerates lipid peroxidation in tissue homogenates by producing free radicals. Interestingly, we observed an antioxidant rather than an expected prooxidant role of ascorbate when human serum supplemented with 1.2mmol/L ascorbate underwent lipid peroxidations initiated by 2mmol/L copper sulfate. The antioxidant role of ascorbate was confirmed by studying the conventional thiobarbituric acid reactive substances (TBARS) as well as by observing the protective effect of ascorbate on the copper-induced peroxidation of unsaturated and polyunsaturated fatty acids. The antioxidation protection provided by ascorbate was comparable to that of equimolar alpha-tocopherol when incubated for 24h. However, lipid peroxidation products were lower in serum supplemented with alpha-tocopherol after 48h of incubation. This effect may be attributed to the binding of copper by plpha-tocopherol after serum proteins, thus preventing direct interaction between cupric ions and ascorbate. This proposed mechanism is based on the observation that the concentration of ascorbate decreased more slowly in serum than in phosphate buffer at physiological pH. Our results also indicate an outstanding anti-oxidant property of human serum due to the chelation of transition metal ions (even at high concentrations) by various serum proteins.     

Blocked 5′ Termini in Brome Mosaic Virus RNA

All four components of brome mosaic virus RNA have m(7)G(5') ppp (5')Gp as their 5' terminus. The m(7)G can be removed by beta-elimination, resulting in the conversion to pppGp.     

Ribonucleic acid synthesis and loss of viability in pea seed

Summary RNA synthesis and protein synthesis in embryonic axis tissue of viable pea (Pisum arvense L. var. N.Z. maple) seed commences during the first hour of germination. Protein synthesis in axis tissue of non-viable pea seed is barely detectable during the first 24 h after the start of imbibition. Nonviable axis tissue incorporates significant levels of [³H]uridine into RNA during this period but the level of incorporation does not increase significantly over the first 24 h of imbibition. In axis tissue of non-viable seed during the first hour of imbibition most of the [³H]uridine was incorporated into low molecular weight material migrating in advance of the 4S and 5S RNA species in polyacrylamide gels but some radioactivity was incorporated into a discrete species of RNA having a molecular weight of 2.7×10⁶. After 24 h, non-viable axis tissue incorporates [³H]uridine into ribosomal RNA, the low molecular weight material migrating in advance of the 4S and 5S RNA peak in polyacrylamide gels and a heterogeneous RNA species of molecular weight ranging from 2.2×10⁶ to 2.7×10⁶. No 4S or 5S RNA synthesis is detectable after 24 h of imbibition in non-viable axis tissue. Axis tissue of viable pea seed synthesises rRNA, 4S and 5S RNA, the low molecular weight material migrating in advance of the 4S and 5S RNA peak in polyacrylamide gels and the rRNA precursor species at both periods of germination studied. Loss of viability in pea seed appears to be accompanied by the appearance of lesions in the processing of rRNA precursor species and a significant loss of RNA synthesising activity.Abbreviations rRNA ribosomal RNA - TCA trichloroacetic acid - SLS sodium lauryl sulphate - PPO 2,5 Diphenyloxazole - POPOP 1,4-Bis-2-(4-methyl-5-penyloxazolyl)-benzene     

Detection of Clostridium botulinum Toxin by Local Paralysis Elicited with Intramuscular Challenge

Clostridium botulinum toxin can be identified by a characteristic, acute local paralysis that follows its injection into the gastrocnemius ("calf" muscle) of mice. The local botulism can be elicited with slightly less than one-tenth the toxin amount that is needed to kill mice by the intraperitoneal (i.p.) challenge route. The practical sensitivities of the intramuscular (i.m.) versus i.p. tests are about equal, however, because maximum sample volume injectable i.m. is 0.1 ml as compared to the 0.5-ml range that can be given i.p. i.m. injection of 10 or more mouse i.p. mean lethal doses causes paralysis in about 1 h, and an i.m. injection of about 0.5 i.p. mean lethal doses causes paralysis in 3 to 4 h. Toxin neutralization by homologous type of antitoxin only can be demonstrated with an incubated mixture of toxin and antitoxin. Although not as convenient as the i.p. method for routine use to detect botulinum toxin, the i.m. method has characteristics which could make it a useful supplement to the presently accepted i.p. procedure.     

Gametic embryogenesis and callogenesis in Isolated microspore culture of Jatropha curcas L. a recalcitrant bioenergy crop

Plant Cell, Tissue and Organ Culture (PCTOC) - Jatropha curcas is an undomesticated crop and its plantations did not meet commercial expectation due to absence of high yielding commercial line with...     

Toxicity of cypermethrin: hsp70 as a biomarker of response in transgenic Drosophila

Heat shock protein induction is often associated with a cellular response to a harmful environment or to adverse life conditions. The main aims of our study were (1) to evaluate the cytotoxic potential of cypermethrin; and (2) to investigate the suitability of stress-induced heat shock protein Hsp70 as a biomarker for environmental pollutants in transgenic Drosophila melanogaster (Hsp70-lacZ)Bg⁹. Different concentrations of cypermethrin (0.002, 0.2, 0.5 and 50.0 p.p.m.) were mixed with food. Third instar larvae of transgenic Drosophila melanogaster were allowed to feed on these mixtures for different time intervals (2, 4, 6, 12, 24 and 48h). Following feeding, hsp70 induction and tissue damage were evaluated. In the highest concentration treatment group (50 p.p.m.), 100% larval mortality was recorded after 12 h exposure. Hsp70 was found to be induced even at the lowest concentration (0.002 p.p.m.) of the insecticide, while tissue damage was observed in the larvae exposed for 48 h. While an insignificant decline in hsp70 expression was observed in the larvae exposed to cypermethrin at a dietary concentration of 0.002 p.p.m. after 48 h compared with those exposed for 24 h, in the next two higher concentrations of the toxicant, a similar but significant decline in hsp70 expression was evident in the exposed larvae after 48 h. The present study reveals the cytotoxic potential of cypermethrin and further proposes that hsp70 induction in transgenic Drosophila melanogaster could be used as a sensitive biomarker in risk assessment.     

Systematic Review and Meta-Analysis of Validation Studies on a Diabetes Case Definition from Health Administrative Records

Objectives

Health administrative data are frequently used for diabetes surveillance. We aimed to determine the sensitivity and specificity of a commonly-used diabetes case definition (two physician claims or one hospital discharge abstract record within a two-year period) and their potential effect on prevalence estimation.

Methods

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched Medline (from 1950) and Embase (from 1980) databases for validation studies through August 2012 (keywords: “diabetes mellitus”; “administrative databases”; “validation studies”). Reviewers abstracted data with standardized forms and assessed quality using Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria. A generalized linear model approach to random-effects bivariate regression meta-analysis was used to pool sensitivity and specificity estimates. We applied correction factors derived from pooled sensitivity and specificity estimates to prevalence estimates from national surveillance reports and projected prevalence estimates over 10 years (to 2018).

Results

The search strategy identified 1423 abstracts among which 11 studies were deemed relevant and reviewed; 6 of these reported sensitivity and specificity allowing pooling in a meta-analysis. Compared to surveys or medical records, sensitivity was 82.3% (95%CI 75.8, 87.4) and specificity was 97.9% (95%CI 96.5, 98.8). The diabetes case definition underestimated prevalence when it was ≤10.6% and overestimated prevalence otherwise.

Conclusion

The diabetes case definition examined misses up to one fifth of diabetes cases and wrongly identifies diabetes in approximately 2% of the population. This may be sufficiently sensitive and specific for surveillance purposes, in particular monitoring prevalence trends. Applying correction factors to adjust prevalence estimates from this definition may be helpful to increase accuracy of estimates.