Heterosis,molecular diversity,combining ability and their interrelationships in short duration maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) across the environments

Five inbred lines, 10 single cross maize (Zea mays L.) hybrids and two standard cultivars as check were used to study the combining abilities and heterosis under three environmental conditions. Random amplified polymorphic DNAs (RAPDs) markers were used to study the genetic diversity (GD) and further to analyze relationship of RAPDs based GD with combining ability and heterosis in short duration maize. Spearman’s rank correlation coefficients and linear regressions were analyzed to identify the most important factor determining heterosis and per se performance of the hybrids. Variances due to general combining ability (GCA), specific combining ability (SCA) and their interactions with environment were found to be significant. Twenty random primers generated 179 RAPD fragments. Of these, 102 RAPD fragments were polymorphic. GD was determined using Jaccard’s similarity coefficient, and a dendogram was constructed by UPGMA cluster analysis. The RAPDs based GD exhibited non-significant negative or positive association, non-significant linear regression along with very low coefficient of determination (R ²) with SCA, high and mid parent heterosis (HP and MP) and per se performance of the hybrids. Significant positive correlations and regressions along with high coefficients of determination were recorded for SCA with HP, MP and per se performance of the hybrids. The HP and MP also established significant positive association and linear regression along with high coefficient of determination with per se performance of hybrids whereas the parental mean did not establish any significant correlations with the GD, HPH, MPH and grain yield of F₁s. The present investigation, therefore, did not find any role of RAPDs based GD in determining hybrid heterosis and hybrid performance in short duration sub-tropical maize. The SCA, however, has emerged as the most important factor in determination of heterosis as well as per se performance of the hybrids in short duration maize.     

Effect of nano-SiO2 on properties of wood/polymer/clay nanocomposites

Wood polymer nanocomposites (WPNC) based on nano-SiO₂ were prepared by impregnation of styrene acrylonitrile copolymer (SAN), SiO₂ nanoparticles modified with γ-trimethoxy silyl propyl methacrylate (MSMA), and nanoclay into wood. The structure of modified SiO₂ nanoparticles and WPNC was characterized by Fourier transform infrared spectroscopy (FTIR). XRD analysis showed the delaminated structure of SAN/SiO₂/clay-treated wood composites. The synergistic effect of nano-SiO₂ and nanoclay was investigated. Thermal stability of SiO₂ nanoparticles decreased after modification, while that of wood treated with SAN, SiO₂, and nanoclay improved. Morphological characteristics were examined by scanning electron microscopy (SEM). Mechanical properties, water uptake (%), dimensional stability, hardness, and flammability were found to improve due to incorporation of SiO₂ and nanoclay into wood polymer composites. Maximum improvement in properties was observed in the wood polymer composites containing SiO₂ and nanoclay at the ratio of 1:1.     

Expression and localization of angiopoietin family in corpus luteum during different stages of oestrous cycle and modulatory role of angiopoietins on steroidogenesis,angiogenesis and survivability of cultured buffalo luteal cells

The objective of this study was to document the expression and localization of angiopoietin (ANGPT) family members comprising of angiopoietin (ANGPT1 and ANGPT2), and their receptors (Tie1 and Tie2) in buffalo corpus luteum (CL) obtained from different stages of the oestrous cycle, and the modulatory role of ANGPT1 and ANGPT2 alone or in combinations on progesterone (P₄) secretion and mRNA expression of phosphotidylinositide‐3kinase‐protein kinase B (PI3K‐AKT), phosphoinositide‐dependent kinase (PDK), protein kinase B (AKT), Bcl2 associated death promoter (BAD), caspase 3 and von willebrand factor (vWF) in luteal cells obtained from midluteal phase (MLP) of oestrous cycle in buffalo. Real‐time RT‐PCR (qPCR), Western blot and immunohistochemistry were applied to investigate mRNA expression, protein expression and localization of examined factors whereas, the P₄ secretion was assessed by RIA. The mRNA and protein expression of ANGPT1 and Tie2 was maximum (p < .05) in mid luteal phase (MLP) of oestrous cycle. The ANGPT2 mRNA and protein expression was maximum (p < .05) in early luteal phase, decreased in MLP and again increased in late luteal phase of oestrous cycle. ANGPT family members were localized in luteal cells and endothelial cells with a stage specific immunoreactivity. P₄ secretion was highest (p < .05) with 100 ng/ml at 72 hr when luteal cells were treated with either protein alone. The mRNA expression of PDK, AKT and vWF was highest (p < .05) and BAD along with caspase 3 were lowest (p < .05) at 100 ng/ml at 72 hr of incubation period, when cultured luteal cells were treated with either protein alone or in combination. To conclude, our study explores the steroidogenic potential of angiopoietins to promote P₄ secretion, luteal cell survival and angiogenesis through an autocrine and paracrine actions in buffalo CL.     

Effect of an immunomodulator on the efficacy of an attenuated vaccine against avian pneumovirus in turkeys

Since 1997, avian pneumovirus (APV) has caused estimated annual losses of $15 million to the Minnesota turkey industry. In order to develop an attenuated live vaccine against APV, we serially passaged a Minnesota isolate of APV (APV/MN/turkey/1-a/97) in vitro in cell cultures for 41 passages. Laboratory experiments with this high-passage virus (P41) indicated that the attenuated virus provided immunogenic protection to turkeys against challenge with virulent APV, although some birds showed mild to moderate dinical signs after inoculation. To reduce the residual pathogenicity of P41, while maintaining its immunogenicity, we decided to vaccinate turkeys with P41 in the presence of an immunomodulator, S-28828 (1-n-butyl-2-ethoxymethyl-1H-imidazo[4,5-c]quinolin-4-amine-hydrochloride), which is a potent cytokine inducer. The combined inoculation of S-28828 (5 mg/kg body weight) and P41 resulted in a significant reduction in the incidence of virus-induced clinical signs in comparison with birds that received P41 without immunomodulator (P < 0.05). Only 17% of birds inoculated with S-28828 + APV P41 showed mild respiratory symptoms at 5 days postinoculation as compared with 46% of the vaccinated turkeys that did not receive S-28828. Vaccination with either P41 or with P41 + S-28828 protected turkeys against dinical signs and viral replication after challenge with virulent APV. These results indicate that immunomodulators, such as S-28828, may act as good vaccine adjuvants that can reduce the pathogenicity but maintain the immunogenicity of partially attenuated vaccines.     

Progress in grafting watermelon to manage Verticillium wilt

Vegetable grafting for disease management was first used successfully when watermelon grafted onto a Cucurbita moschata rootstock overcame Fusarium wilt. Interspecific grafting has since been used effectively to mitigate several soilborne pathogens in a variety of solanaceous and cucurbitaceous cropping systems. Verticillium wilt caused by Verticillium dahliae is a significant disease in watermelon crops and is difficult to manage. Current management practices, including crop rotation, soil fumigation, and host resistance, are insufficient due to the ability of microsclerotia to persist in absence of a host, lack of efficacy of soil fumigants, and limited availability of resistant cultivars. Watermelon grafted onto commercial cucurbit rootstocks have increased tolerance to Verticillium wilt, although no cucurbit rootstocks are known to be completely resistant. Verticillium wilt incidence decreased on grafted plants grown in artificially and naturally infested soils, while scion health and growth as well as rootstock root mass and vigour increased. Commonly used rootstocks are Lagenaria siceraria, C. moschata, and C. maxima × C. moschata; of these, only C. maxima × C. moschata ‘Tetsukabuto’ reduced severity of Verticillium wilt across several scion cultivars, locations, years, and soil densities of V. dahliae. Although studies on Verticillium wilt resistance of grafted watermelon are few, their combined results suggest the threshold of V. dahliae soil density for watermelon may be around 5–12 cfu/g. This review summarizes available information on Verticillium wilt of watermelon and effects of different rootstock × scion combinations, assisting growers and breeding programmes in decisions to adopt watermelon grafting for management of Verticillium wilt.     

Antibacterial activity of embelin

Embelin, a benzoquinone-derivative isolated from Embelia ribes, when tested for its antibacterial potential exhibited significant inhibition against five and moderate activity against three strains of the 12 bacteria tested.     

Insecticidal action of the polyphenolic rich fractions from the stem bark of Streblus asper on Dysdercus cingulatus

Extracts from the stem bark of Streblus asper possess insecticidal activity against the fifth instar of Dysdercus cingulatus. Methanolic extract showed an LC(50) value of 5.56 microg/insect. Partition with chloroform increased the insecticidal activity (LC(50) 2.01 microg/insect). Three polyphenolic rich fractions were obtained from silica-gel column chromatography of the chloroform fraction and found to have noteworthy insecticidal activity (LC(50): 1.82 microg, 2.70 microg, 2.26 microg/insect) by topical application. This may provide a useful beginning for the development of biopesticides.     

Effect of nanofillers on flame retardancy, chemical resistance, antibacterial properties and biodegradation of wood/styrene acrylonitrile co-polymer composites

Wood polymer nanocomposites (WPNCs) based on simul wood (Bombex ceiba, L.) were prepared by impregnation of styrene acrylonitrile copolymer, γ-methacryloyloxy trimethyl silane-modified TiO₂, SiO₂ nanoparticles and nanoclay intercalating mixture through vacuum impregnation. The impact of nanofillers on the physical properties, flame retardancy, water resistance, anti-swelling efficiency and biodegradability of the resultant WPNCs was investigated. Remarkable enhancement in wood properties such as flame retardancy, water resistance and anti-swelling efficiency was achieved with the treatment. The results showed that all the properties were maximum for wood samples treated with SAN/TiO₂ (0.5 %)/SiO₂ (0.5 %)/nanoclay (0.5 %). The presence of TiO₂ nanoparticles in WPNC exhibited antibacterial activity. The resistance to biodegradation was observed by incorporation of nanofillers into wood.