Molecular characterization of Lepidopteran specific Bacillus thuringiensis strains isolated from Hilly Zone Soils of Karnataka, India

Bacillus thuringiensis (Bt) strains pathogenic to Lepidopteran insects and native to hilly zone soils of Karnataka (India) were explored. 19 strains were isolated from the soils and identified by morphological and microscopic characters. Toxicity level of the Bt isolates was tested by treating third Instar larvae of silkworm (Bombyx mori L.) and mulberry leaf roller (Diaphania pulverulentalis). Mortality rate of the insect larvae treated with Bt isolates was ranged from 20 to 80%. A few isolates namely, Bt2, Bt6, Bt8, and Bt14 strains were more virulent (caused >50% death) than others. Detection of cry genes using cry gene specific primers by polymerase chain reaction (PCR) revealed the presence of at least one of the cry genes. In one of the isolates (Bt9), the cry gene was not detected. The Cry1Ac gene was abundant and it was detected in 13 isolates. Cluster analysis for genetic diversity showed two major groups and four sub groups.Keywords: Molecular characterization, Bacillus thuringiensis, bioassay, genetic diversity, Cry genes, hilly zoneAfrican Journal of Biotechnology Vol. 12(20), pp. 2924-293

Genetic Engineering of the Cry Gene as a Source of Resistance to Insect Pest of Some Major Crops

In recent times, genetic engineering has become a source of agriculture innovations, providing a new solution to the age of old problems. Transfers of genes between plant species have played an important role in crop development for many decades. Advancement field of genetic engineering have provided new technologies for gene identification and gene transfer into plants has provided the opportunity for genetically engineering insect pest resistance into agriculturally desirable cultivars without altering critical quality traits. Bt toxin gene the source of the insecticidal toxins produced in commercial transgenic plants is the soil bacterium Bacillus thuringiensis (Bt). Bacillus thuringiensis synthesizes crystalline proteins during sporulation. These crystalline proteins are highly insecticidal at very low concentrations. With the advent of molecular biology and genetic engineering, it has become possible to use Bt more effectively and rationally by introducing the cry genes of Bt in crop plants. The bacterium produces an insecticidal crystal protein (ICP: also called Cry proteins, encoded by cry genes). The toxin protein binds to specific receptors present in the midgut epithelial membranes. The disturbances in osmotic equilibrium and cell lysis lead to insect paralysis and death. Scientists have mitigated this risk through stacking or pyramiding different genes such as multiple but different Cry genes and Cry genes combined with other insecticidal proteins, which target different receptors in insect pests but also provide resistance to a wider range of pests. Alternatively, synthetic variants of Cry genes has been employed as in the case of MON863 which expresses a synthetic Bt kumamotoensis Cry3Bb1 gene against maize rootworm, which is eight times more effective than the native, non-modified version. The success of the transgenic approach led to the development of Bt crops, transgenic crops are used worldwide to control major pests of rice, cotton, maize and soybean. Rice effective against lepidopteron pests, Cotton (Gossypium hirsutum) tolerant to lepidopteran larvae (caterpillars), maize (Zea mays) tolerant to both lepidopteran and coleopteran larvae (rootworms) and soya bean (Glycine max) both lepidopteran and coleopteran larvae have become widely used in global agriculture and have led to reductions in pesticide usage and lower production costs. To overcome resistance acquired by insects against Cry toxins different strategies were employed to modify Cry functional domains to improve their toxicity. Therefore, multiple mutations/adaptations need to be made by target pests in order to develop resistance to this robust new generation of insect resistant crops. Keywords: Cry gene, Genetic engineering, Source of resistance to insect pest DOI: 10.7176/JBAH/11-7-04 Publication date: April 30th 202

Cry genes profile and proteolytic activity of native Bacillus thuringiensis strains against Spodoptera frugiperda

Introduction: Bacillus thuringiensis (Bt) produces entomopathogenic Cry proteins which are activated to pathogenic form by proteases. Objective: Determination of cry genes and proteolytic activity in three native Bt strains. Material and methods: Total DNA was isolated with the CTAB technique. Cry 1 and 2 genes were amplified with general and specifics primers. Proteolytic activity was assayed by using azocasein as substrate. Results and Discussion: Specific cry genes and the biomass-bound protease activity are showed in the table. Bt RT displayed different cry specific content than the others strains. In addition to Cry protein, Bt is also an excellent source of protease activities. Bt RT has a proteolytic activity significantly different to that achieved for the reference strain Bt 4D1 (P> 0.05, Tukey test). This work was supported by grants PICTO-UNT 761 and PIP 6062 (CONICET).Fil: Alvarez, Analia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pera, Licia Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Baigori, Mario Domingo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXXV Jornadas Científicas de la Asociación de Biología de TucumánTafi del ValleArgentinaAsociacion de Biologia de Tucuma

Circadian clocks and breast cancer

Circadian clocks respond to environmental time cues to coordinate 24-hour oscillations in almost every tissue of the body. In the breast, circadian clocks regulate the rhythmic expression of numerous genes. Disrupted expression of circadian genes can alter breast biology and may promote cancer. Here we overview circadian mechanisms, and the connection between the molecular clock and breast biology. We describe how disruption of circadian genes contributes to cancer via multiple mechanisms, and link this to increased tumour risk in women who work irregular shift patterns. Understanding the influence of circadian rhythms on breast cancer could lead to more efficacious therapies, reformed public health policy and improved patient outcome

New combinations of cry genes from Bacillus thuringiensis strains isolated from northwestern Mexico

Twenty eight Bacillus thuringiensis strains isolated from the Tijuana-Ensenada region of northwestern Mexico were analyzed to determine the distribution of cry and cyt genes. Crystal production by the strains was examined by scanning electron microscopy, which showed the predominance of cubic crystals. Alkaline-dissolved and trypsin activated crystals were also analyzed by SDS-PAGE, yielding bands of 40-200 kDa. The cry1 and cry2 genes were molecularly characterized using general and newly designed specifi c primers in addition to other oligonucleotides (cry3, cry4, cry8, cry9, cry11, Nem, cry25, cry29 and cyt), resulting in the identifi cation of novel gene combinations. The use of specifi c primers for cry1A, cry1B, cry1C, cry1D, cry1E, cry1F and cry2Aa, cry2Ab, cry2Ac, cry2Ad showed differences in the distribution of cry1 (36 %), cry2 (71 %), and cyt (40 %) in strains from Tijuana-Ensenada compared to other previously studied regions. Bioassays were conducted on Manduca sexta larvae to analyze the Cry insecticidal capacity of the isolated strains. The hemolytic activity of the Cyt toxinfrom the same strains was assessed in human erythrocytes. [Int Microbiol 2012; 15(4):209-216