The effects of silicon level in nutrient solution on the uptake and distribution of silicon in zucchini and zinnia, and its interaction with the uptake of selected elements

The beneficial role of silicon (Si) in the growth of some plants is linked to its uptake and accumulation inside their tissue. However, the optimum level of Si in the nutrient solution that can provide maximum benefits and its interaction with other elements is less understood. A study was conducted to evaluate the impact of different levels of soluble Si in nutrient solutions on the uptake and distribution of Si and other elements into different parts of zucchini and zinnia, and its effects on the growth of these two plants. Increasing the concentrations of Si in the nutrient solution increased the accumulation of Si (in leaves and roots) and potassium (in stem and petiole) and reduced calcium without affecting the levels of magnesium and phosphorus in different organs of both plants. Application of Si at 50 mg L-1 resulted in maximal accumulations of P, Ca and Mg in both plants and increased their growth. However, the application of higher levels of Si caused stunting. For optimal benefits, application of Si at 50 to 100 mg L-1 is recommended for these plants.Keywords: Accumulation, distribution, growth, silicon, uptake, zinnia, zucchiniAfrican Journal of Biotechnology Vol. 12(14), pp. 1617-162

DNA fingerprinting of spore-forming bacterial isolates, using Bacillus cereus repetitive polymerase chain reaction analysis (Bc-Rep-PCR)

Bc-repetitive extragenic palindromic polymerase chain reaction (Bc-Rep PCR) analysis was conducted on seven Bacillus thuringiensis isolates accessed from the Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ) culture collection and on five local isolates of entomopathogenic spore-forming bacteria. The five isolates were three strains of B. thuringiensis, one strain of B. cereus and one strain of Brevibacillus laterosporus. All five isolates were distinguished from each other using Bc-Rep PCR analysis. The three B. thuringiensis isolates were closely related. The isolate of B. laterosporus was not related to any of the B. cereus group isolates. Serotyping was also conducted on the five local isolates. However, only one of these isolates could be identified with serotyping and was identified as B. thuringiensis subsp. kenyae.Keywords: Bc-repetitive extragenic palindromic polymerase chain reaction, Bacillus sp., serotypingAfrican Journal of Biotechnology Vol. 12(14), pp. 1598-160

Application of selected biological control agents in conjunction with tolclofos-methyl for the control of damping-off caused by Rhizoctonia solani

Selected Trichoderma and Bacillus isolates were tested as seed treatments with reduced concentrations of tolclofos-methyl against Rhizoctonia solani damping-off using cucumber as test plants. In vitro bioassays using filter paper disc infused with six concentrations [active ingredient (ai)]of tolclofos-methyl (0.005, 0.05, 0.125, 0.25, 0.5 and 1.5 g ai/l) showed that growth of Trichoderma isolates on agar plates were less inhibited at 0.005 and 0.05 g ai/l than 0.125 – 1.5 g ai/l tolclofos-methyl concentrations while Bacillus isolates were not affected by any of the six concentrations. In a greenhouse study with a 0.05 g ai/l tolclofos-methyl concentration, Trichoderma and Bacillus isolates applied alone or in combination to cucumber seeds resulted in a better disease control than the Trichoderma and Bacillus treatments used alone. As high as 86% disease control was achieved by combining 0.05 g ai/l tolclofos-methyl with T. harzianum Isolate SYN which was significantly better (P =0.001) than the 0.05 g ai/l tolclofos-methyl control. In all cases, additive effects of combining 0.05 g ai/l tolclofos-methyl with Trichoderma and Bacillus treatments were observed

Preliminary investigation of the crossing of bambara nut (Vigna subterranea [L.] Verdc.)

Effective crosses among selected parents are crucial for genetic analyses and for the breeding of crop plants. Bambara nut is an indigenous African legume with considerable genetic diversity useful for genetic enhancement of yield and quality traits through breeding. However, the crop has previously received limited research attention. This may be attributed to its extremely small flower size, its flower orientation, the delicate nature of the flower and it’s mating system. The aim of this study was to establish a preliminary crossing protocol for Bambara nut for breeding and genetic studies. Controlled emasculation and pollination were performed using eight selected parents, using a diallel mating scheme under glasshouse conditions. Some successful crosses were achieved and F1 seeds were recovered from the crosses of 211-40-1 x N211-2, N212-8 x 211-40-1 and M09-3 x 211-82-1.Keywords: Bambara nut, emasculation, crossing, pollination, F1 hybridsAhmadu Bello University Zaria, Nigeri

Effects of single and combined inoculations of selected Trichoderma and Bacillus isolates on growth of dry bean and biological control of Rhizoctonia solani damping-off

Six Trichoderma isolates, Trichoderma atroviride strain 3A, T. atroviride strain 6, Trichoderma harzianum, strain SY, Trichoderma pseudokoningii, an unidentified strain Trichoderma sp. strain 2F and T. harzianum strain kmd and three Bacillus subtilis isolates, B. subtilis B69, B. subtilis B77 and B. subtilis B81, were tested in vivo, singly and each in combination for growth promotion of dry beans and biological control of damping-off caused by Rhizoctonia solani in cucumber. All fungal and bacterial isolates were applied as seed treatments in greenhouse and rhizotron studies. Greenhouse trials showed that combined inoculations of T. atroviride strain 6 and B. subtilis B69 gave the highest growth promotion of bean in terms of seedling dry biomass (43.0% over uninoculated control). Rhizotron studies supported these findings, where it was shown that root biomass and root area were increased. However, results obtained for bean yield trials were inconsistent and had no correlation with the seedling trials (P = 0.87 and P = 0.35). No increase was obtained in protein or fat content of bean seed for any of the selected isolates and/or their combinations tested in two separate greenhouse yield trials. In the biological control trials, single inoculations of T. harzianum strain kmd, T. atroviride strain 3A and T. harzianum strain SY gave the highest percentage survival of cucumber plants in the greenhouse. None of the Trichoderma plus Bacillus combinations were better than the single inoculations of T. harzianum strain kmd, T. atroviride strain 3A and T. harzianum strain SY. The performances, particularly of B. subtilis B69 and B81 were enhanced when combined with T. atroviride strain 3A, T. atroviride strain 6, T. harzianum strain SY or T. harzianum strain kmd. The performance of each of the Trichoderma and Bacillus combinations was better than the Bacillus isolates used alone. This study showed that there was potential in using mixtures of Trichoderma and Bacillus for improving plant growth and disease control.Key words: Bacillus, dry bean, plant growth promotion, Trichoderma

Development of a single nucleotide polymorphism (SNP) marker for detection of the low phytic acid (lpa1-1) gene used during maize breeding

Breeding for low phytic acid (LPA) in maize is hampered by a tedious and destructive colorimetric assay in mature dry grain. There are no molecular markers available for the single recessive gene of lpa1-1, restricting breeding programmes. The aim of this study is to develop a molecular marker to identify the lpa1-1 gene at the early vegetative plant stage. The parental lines are temperate LPA line (CM 32) and tropical line (P 16). The lpa1-1 allele is due to a single amino acid change from alanine to valine. The nature of the single nucleotide polymorphism (SNP) marker was validated by DNA sequencing of the parental PCR products. Using high resolution melt (HRM) profiles and normalised difference plots, we successfully differentiated the homozygous dominant (wild type), homozygous recessive (LPA) and heterozygous genotypes. The reduced phytate content of the LPA parental line was confirmed. The profiles from low cost crude and high quality DNA extraction were comparable when distinguishing between the parental lines. The cost of HRM analysis was 8% of the cost of PCR amplification and DNA sequencing. The development of the marker will make maize breeding for LPA efficient and fast, and it will enable the earlier release of lpa1-1 varieties.Keywords: High resolution melt (HRM) analysis, low phytic acid, maize, single nucleotide polymorphism (SNP) markerAfrican Journal of Biotechnology Vol. 12(9), pp. 892-90

Early Colorectal Responses to HIV-1 and Modulation by Antiretroviral Drugs.

Innate responses during acute HIV infection correlate with disease progression and pathogenesis. However, limited information is available about the events occurring during the first hours of infection in the mucosal sites of transmission. With an ex vivo HIV-1 challenge model of human colorectal tissue we assessed the mucosal responses induced by R5- and X4-tropic HIV-1 isolates in the first 24 h of exposure. Microscopy studies demonstrated virus penetration of up to 39 μm into the lamina propia within 6 h of inoculation. A rapid, 6 h post-challenge, increase in the level of secretion of inflammatory cytokines, chemokines, interferon- γ (IFN-γ), and granulocyte-macrophage colony-stimulating factor (GM-CSF) was observed following exposure to R5- or X4-tropic isolates. This profile persisted at the later time point measured of 24 h. However, exposure to the X4-tropic isolate tested induced greater changes at the proteomic and transcriptomic levels than the R5-tropic. The X4-isolate induced greater levels of CCR5 ligands (RANTES, MIP-1α and MIP-1β) secretion than R5-HIV-1. Potential drugs candidates for colorectal microbicides, including entry, fusion or reverse transcriptase inhibitors demonstrated differential capacity to modulate these responses. Our findings indicate that in colorectal tissue, inflammatory responses and a Th1 cytokine profile are induced in the first 24 h following viral exposure

Large cell neuroendocrine lung carcinoma: consensus statement from The British Thoracic Oncology Group and the Association of Pulmonary Pathologists

Over the past 10 years, lung cancer clinical and translational research has been characterised by exponential progress, exemplified by the introduction of molecularly targeted therapies, immunotherapy and chemo-immunotherapy combinations to stage III and IV non-small cell lung cancer. Along with squamous and small cell lung cancers, large cell neuroendocrine carcinoma (LCNEC) now represents an area of unmet need, particularly hampered by the lack of an encompassing pathological definition that can facilitate real-world and clinical trial progress. The steps we have proposed in this article represent an iterative and rational path forward towards clinical breakthroughs that can be modelled on success in other lung cancer pathologies

Transmission of highly virulent community-associated MRSA ST93 and livestock-associated MRSA ST398 between humans and pigs in Australia

Pigs have been recognised as a reservoir of livestock associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in Europe, Asia and North America. However, little is known about the presence and distribution of MRSA in the Australian pig population and pig industry. This study describes the presence, distribution and molecular characteristics of the human adapted Australian CA-MRSA ST93 isolated from pigs, people, and the environment within a piggery. Isolates were subjected to antibiotic susceptibility testing, DNA microarray, whole genome sequencing, multi locus sequence typing, virulence and resistance gene characterization and phylogenetic analysis. MRSA were isolated from 60% (n = 52) of farm workers where 84% of isolates returned ST93 and the rest ST398. Of the thirty-one pig isolates tested further, an equal number of ST398 and ST93 (15 each) and one as ST30-V were identified. Four of six environmental isolates were identified as ST93 and two as ST398. This study has identified for the first time in Australia the occurrence of CA-MRSA ST93 and LA-MRSA ST398 amongst farm workers, pigs, and the farm environment. Comparative genome analysis indicates that ST398 is likely to have been introduced into Australia from Europe or North America. This study also reports the first linezolid resistant MRSA isolated in Australia