Gibberellin like Substances in Parts of Developing Barley Grain

In husks, the activity of gibberellin-like substances extracted with aqueous methanol (M-“free” GAs) showed a maximum on the 9th day after pollination. In developing embryos, M-“free” GAs showed no biological activity, whereas biological active component(s) were obtained when the embryos were extracted with Tris buffer. The “free” GAs found in the buffer homogenates (B-“free” GAs) of developing embryos showed a maximum of activity on the 33rd day after pollination. Bound GAs recovered from the precipitated protein of the buffer homogenate (“Protein-bound” GAs) were found in embryo and endosperm. Developing endosperm generally contains the major amount of the extractable gibberellin-like substances. In this tissue, the amount of all examined fractions (M-“free” GAs, B-“free” GAs and “protein-bound” GAs) increased after pollination to reach a maximum on the 21st day, before decreasing to a minimum at grain maturity. Moreover, the curves for dry weight increase and gibberellin like substances follow a remarkably similar course, with the latter reaching its maximim slightly earlier than the former one. This result indicates that gibberellines may participate in the regulation of the accumulation process in the endosperm of barley grain.     

chokh/rx3 specifies the retinal pigment epithelium fate independently of eye morphogenesis

Despite the importance of the retinal pigment epithelium (RPE) for vision, the molecular processes involved in its specification are poorly understood. We identified two new mutant alleles for the zebrafish gene chokh (chk), which display a reduction or absence of the RPE. Unexpectedly, the neural retina (NR) in chk is specified and laminated, indicating that the regulatory network leading to NR development is largely independent of the RPE. Genetic mapping and molecular characterization revealed that chk encodes Rx3. Expression analyses show that otx2 and mitfb are not expressed in the prospective RPE of chk, indicating that the retinal homeobox gene rx3 acts upstream of the molecular network controlling RPE specification. Cellular transplantations demonstrate that rx3 function is autonomously required to specify the prospective RPE. Though rx2 is also absent in chk, neither rx2 nor rx1 is required for RPE development. Thus, our data provide the first indication that, in addition to controlling optic lobe evagination and proliferation, chk/rx3 also determines cellular fate.     

Characterization of deoxy- and ribo-containing oligonucleotide substrates in the hammerhead self-cleavage reaction

Deoxynucleotides were introduced into a substrate fragment of the hammerhead RNA self-cleaving domain. A substrate lacking the 2' hydroxyl adjacent to the cleavage site showed no detectable cleavage under a variety of reaction conditions. Competition experiments indicate that this fragment binds to the ribozyme with an affinity similar to the all RNA fragment, suggesting that the attacking 2' hydroxyl does not substantially contribute to the binding of substrate to ribozyme. Similar competition experiments with the all DNA substrate indicate a much lower affinity for the ribozyme perhaps due to the lack of other 2' hydroxyls. A substrate containing all deoxy residues except for a ribonucleotide at the cleavage site was also shown to be active.     

Do Maternal Knowledge and Attitudes towards Childhood Immunizations in Rural Uganda Correlate with Complete Childhood Vaccination?

Improving childhood vaccination coverage and timeliness is a key health policy objective in many developing countries such as Uganda. Of the many factors known to influence uptake of childhood immunizations in under resourced settings, parents’ understanding and perception of childhood immunizations has largely been overlooked. The aims of this study were to survey mothers’ knowledge and attitudes towards childhood immunizations and then determine if these variables correlate with the timely vaccination coverage of their children. From September to December 2013, we conducted a cross-sectional survey of 1,000 parous women in rural Sheema district in southwest Uganda. The survey collected socio-demographic data and knowledge and attitudes towards childhood immunizations. For the women with at least one child between the age of one month and five years who also had a vaccination card available for the child (N = 302), the vaccination status of this child was assessed. 88% of these children received age-appropriate, on-time immunizations. 93.5% of the women were able to state that childhood immunizations protect children from diseases. The women not able to point this out were significantly more likely to have an under-vaccinated child (PR 1.354: 95% CI 1.018–1.802). When asked why vaccination rates may be low in their community, the two most common responses were “fearful of side effects” and “ignorance/disinterest/laziness” (44% each). The factors influencing caregivers’ demand for childhood immunizations vary widely between, and also within, developing countries. Research that elucidates local knowledge and attitudes, like this study, allows for decisions and policy pertaining to vaccination programs to be more effective at improving child vaccination rates.     

Partial characterization of cotton plants expressing two toxin proteins from Bacillus thuringiensis: relative toxin contribution, toxin interaction, and resistance management

Abstract:  Laboratory studies were performed to characterize the lepidopteran toxicity of cotton plants expressing two different toxin proteins from Bacillus thuringiensis (Bt), in order to assess insect resistance management implications of a commercial, two-toxin transgenic cotton. An independent and additive interactive effect of two Bt δ -endotoxins expressed by the transgenic cotton variety 15985 was demonstrated by examining the responses of Heliothis virescens (F.), Helicoverpa zea (Boddie), and Spodoptera frugiperda (J.E. Smith) larvae to field- or greenhouse-grown tissue from genetic near-isolines, which expressed Cry1A only, Cry2Ab only, or both toxins. In all cases, the Cry2Ab component was the larger contributor to total toxicity in the two-toxin isoline. Toxin-specific, quantitative enzyme-linked immunosorbent assay (ELISA) tests confirmed that the levels of each toxin in tissues of the two-toxin isoline were not statistically different (P > 0.05) from the levels found in the corresponding tissues of the respective single-toxin isoline. Resistance management considerations were discussed. Considering the additive interaction of toxins, a relatively simple insect resistance-monitoring procedure was proposed for the monitoring of commercial cotton varieties expressing both toxins.     

A new triterpene glucoside from Cymbidium giganteum

A new triterpene glucoside, cymbidoside, has been isolated from Cymbidium giganteum. Its structure is shown to be 4ξ-(β-d-glucopyranosyloxymethyl)-14α-methyl-22ξ, 24ξ, 25,28-tetrahydroxy-9,19-cyclo-5α,9β-ergostan-3-one.     

Protein glycosylation mutants of procyclic Trypanosoma brucei: defects in the asparagine-glycosylation pathway

We employed a genetic approach to study protein glycosylation in the procyclic form of the parasite Trypanosoma brucei. Two different mutant parasites, ConA 1-1 and ConA 4-1, were isolated from mutagenized cultures by selecting cells which resisted killing or agglutination by concanavalin A. Both mutant cells show reduced concanavalin A binding. However, the mutants have different phenotypes, as indicated by the fact that ConA 1-1 binds to wheat germ agglutinin but ConA 4-1 and wild type do not. A blot probed with concanavalin A revealed that many proteins in both mutants lost the ability to bind this lectin, and the blots resembled one of wild type membrane proteins treated with PNGase F. This finding suggested that the mutants had altered asparagine- linked glycosylation. This conclusion was confirmed by studies on a flagellar protein (Fla1) and procyclic acidic repetitive protein (PARP). Structural analysis indicated that the N- glycan of wild type PARP is exclusively Man5GlcNAc2 whereas that in both mutants is predominantly a hybrid type with a terminal N- acetyllactosamine. The occupancy of the PARP glycosylation site in ConA 4-1 was much lower than that in ConA 1-1. These mutants will be useful for studying trypanosome glycosylation mechanisms and function.