Flexural and Dynamic Mechanical Properties of Alkali-Treated Coir/Pineapple Leaf Fibres Reinforced Polylactic Acid Hybrid Biocomposites

Polylactic acid(PLA)possesses good mechanical and biodegradability properties which make it a suitable material for polymer composites whereas brittleness and high costs limit its utilization in various applications.The reinforcement of natural fibres with biopolymers has been formed to be an efficient technique to develop composites having the ability to be fully biodegradable.This study concerns with the incorporation of various percentages of untreated and alkali-treated Coir Fibres(CF)and pineapple leaf fibres(PALF)in PLA biocomposites and characterizations of flexural,morphological and dynamic mechanical properties.Flexural properties showed that the treated C1P1 hybrid composites(C1P1A)displayed highest flexural strength(35.81 MPa)and modulus(5.28 GPa)among all hybrid biocomposites.Scanning Electron Micros-copy(SEM)revealed a behaviour of fibre-matrix adhesion in untreated treated biocomposites.SEM observation revealed good dispersion of the fillers in PLA.Dynamic mechanical analysis revealed that C1P1A showed highest glass transition temperature(Tg)and storage modulus(E')while untreated C3P7 displayed the least Tg and E'.Overall findings showed that alkali-treated hybrid biocomposites(CF/PALF/PLA)especially C1P1A have improved flexural properties,dynamic and morphological properties over untreated biocomposites.Success of these findings will provide attracting consideration of these hybrid biocomposites for various lightweight uses in a broad selection of industrial applications such as biomedical sectors,automobile,construction,electronics equipment,and hardware tools.     

ADVENTIVE EMBRYOGENESIS IN CITRUS AND ITS RELATION TO POLLINATION AND FERTILIZATION

Cytological and histological studies of seeds from three facultative apomictic Citrus cultivars show that adventive embryos develop, as a rule, from the first few cell layers of the nucellus adjacent to the embryo sac in the micropylar half and occasionally from the chalazal end. The adventive embryos initiated in nucellar tissue away from the embryo sac and most of those initiated from the chalazal end of the nucellus do not develop beyond the one-celled stage. When two or more embryos are developing in the same seed, the successful development of a given embryo depends on its location in relation to access to nutrients from the endosperm. The presence of a zygote and triploid endosperm in seeds with adventive embryos, the abortion of seed when endosperm degenerates, and the lack of seed set without pollination indicate that pollination and fertilization are essential for in vivo adventive embryogenesis.     

Optimization of medium composition by response surface methodology for the production of tartaric acid by Gluconobacter suboxydans

The combined effect of sorbitol and yeast extract of the medium on tartaric acid production by Gluconobacter suboxydans, NCIM 2049, was studied in batch fermentation while keeping the temperature (30?°C) and pH (6.2) constant. Response surface methodology was used to obtain quadratic models for the production of tartaric acid. The multiple coefficients of regression between 0.8945 and 0.9820 was obtained during the process. The optimum medium composition comprising 20?kg/m³ sorbitol and 2?kg/m³ yeast extract was verified experimentally by observing the variation of cell mass and tartaric acid production with time.     

Soil-applied zinc and copper suppress cadmium uptake and improve the performance of cereals and legumes

The present study aimed to evaluate the effect of soil-applied Zn and Cu on absorption and accumulation of Cd applied through irrigation water in legume (chickpea and mung bean) and cereal (wheat and maize) crops. The results revealed that Cd in irrigation water at higher levels (2 and 5 mg L^?1) significantly (p < 0.05) reduced the plant biomass while the soil application of Zn and Cu, singly or combined, favored the biomass production. Plant tissue Cd concentration increased linearly with the increasing application of Cd via irrigation water. While Cd application caused a redistribution of metals in grains, straw, and roots with the highest concentration of Cd, Zn, and Cu occurred in roots followed by straw and grains. Zinc addition to soil alleviated Cd toxicity by decreasing Cd concentration in plant tissues due to a possible antagonistic effect. The addition of Cu to the soil had no consistent effects on Zn and Cd contents across all crops. Inhibitory effects of Cd on the uptake and accumulation of Zn and Cu have also been observed at higher Cd load. Thus, soil-applied Zn and Cu antagonized Cd helping the plant to cope with its toxicity and suppressed the toxic effects of Cd in plant tissues, thus favoring plant growth.     

A 23.8-kD alpha-zein with N-terminal sequence and immunological properties similar to 26.7-kD alpha-zeins

A 23.8-kD alpha-zein polypeptide, K55PC7, has been shown to be a truncated member of the 26.7-kD alpha-zein class based on its amino acid composition, N-terminal sequence, and immunological properties. This unusual polypeptide was isolated by chromatographing whole alpha-zein from inbred K55. The N-terminal sequence of K55PC7 is highly homologous to those of 4 putative 26.7-kD alpha-zeins but shows no homology to those of 10 putative alpha-zeins that belong to the 23.8-kD class. Its higher valine and lower phenylalanine contents also suggest that K55PC7 is a member of the 26.7-kD class. In addition, studies with antibodies raised to peptides corresponding to regions unique to each of the two alpha-zein classes indicate that K55PC7 has immunological similarity to 26.7-kD alpha-zeins. Peptide mapping data suggest that K55PC7 is not the putative product of the truncated 26.7-kD alpha-zein gene zA1 isolated from inbred W64A and described by Spena et al. [26]. It appears that K55PC7 occurs as a major component in inbred K55 and is a truncated version of a 26.7-kD alpha-zein, arisen either by an internal deletion or premature termination due to a nonsense mutation.Abbreviations SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - EIF isoelectric focusing - SP sulfopropyl-Sephadex - PC phosphocellulose - DSS disuccinimidyl suberate - MBC m-maleimido-benzoyl-N-hydroxysuccinimide - 2-ME 2-mercaptoethanol     

Additions to the List of Graphidaceae (Lichenized Ascomycetes) in Pakistan

Biology Bulletin - As part of comprehensive study of lichen diversity of northern areas of Pakistan using molecular and morphological approaches, we found four species of the family Graphidaceae....     

Genotoxic effects of heavy metal cadmium on growth,biochemical, cyto-physiological parameters and detection of DNA polymorphism by RAPD in Capsicum annuum L. – An important spice crop of India

The present study was designed to investigate the effects of cadmium (Cd) on biochemical, physiological and cytological parameters of Capsicum annuum L. treated with five different concentrations (20, 40, 60, 80 and 100 ppm) of the metal. Shoot–root length, pigment and protein content showed a continuous decrease with increasing Cd concentrations and the maximal decline was observed at the higher concentration. Proline content was found to be increased upto 60 ppm while at higher concentrations it gradually decreased. MDA content and chromosomal aberrations increased as the concentration increased. Additionally Random amplified polymorphic DNA (RAPD) technique was used for the detection of genotoxicity induced by Cd. A total of 184 bands (62 polymorphic and 122 monomorphic) were generated in 5 different concentrations with 10 primers where primer OPA-02 generated the highest percentage of polymorphism (52.63%). Dendrogram showed that control, R1 and R2 showed similar cluster and R4 and R5 grouped with R3 into one cluster, which showed that plants from higher doses showed much difference than the plants selected at mild doses which resemble control at the DNA level. This investigation showed that RAPD marker is a useful tool for evaluation of genetic diversity and relationship among different metal concentrations.     

Calcitriol–copper interaction leads to non enzymatic,reactive oxygen species mediated DNA breakage and modulation of cellular redox scavengers in hepatocellular carcinoma

Calcitriol is the metabolically active form of Vitamin D and is known to kill cancer cells. Using the rat model of DEN induced hepatocellular carcinoma we show that there is a marked increase in cellular levels of copper in hepatocellular carcinoma and that calcitriol–copper interaction leads to reactive oxygen species mediated DNA breakage selectively in hepatocellular carcinoma cells. In vivo studies show that calcitriol selectively induces severe fluctuations in cellular enzymatic and non enzymatic scavengers of reactive oxygen species in the malignant tissue. Lipid peroxidation, a well established marker of oxidative stress, was found to increase, and substantial cellular DNA breakage was observed. We propose that calcitriol is a proxidant in the cellular milieu of hepatocellular carcinoma cells, and this copper mediated prooxidant action of calcitriol causes selective DNA breakage in malignant cells, while sparing normal (non malignant) cells.     

Modulation of endothelium function by fatty acids

Molecular and Cellular Biochemistry - The endothelium acts as the barrier that prevents circulating lipids such as lipoproteins and fatty acids into the arterial wall; it also regulates normal...