David A. Fischhoff

Bio: David A. Fischhoff is an academic researcher from Monsanto. The author has contributed to research in topics: Bacillus thuringiensis & Gene. The author has an hindex of 17, co-authored 34 publications receiving 4783 citations.

Radically rethinking agriculture for the 21st century.

Abstract: Population growth, arable land and fresh water limits, and climate change have profound implications for the ability of agriculture to meet this century’s demands for food, feed, fiber, and fuel while reducing the environmental impact of their production. Success depends on the acceptance and use of contemporary molecular techniques, as well as the increasing development of farming systems that use saline water and integrate nutrient flows.

Modification of the coding sequence enhances plant expression of insect control protein genes.

Abstract: Increased expression of the insect control protein genes of Bacillus thuringiensis in plants has been critical to the development of genetically improved plants with agronomically acceptable levels of insect resistance. The expression of the cryIA(b) gene was compared to partially modified (3% nucleotide difference) and to fully modified (21% nucleotide difference) cryIA(b) and cryIA(c) genes in tobacco and tomato. The modified genes increased the frequency of plants that produced the proteins at quantities sufficient to control insects and dramatically increased the levels of these proteins. Among the most highly expressing transformed plants for each gene, the plants with the partially modified cryIA(b) gene had a 10-fold higher level of insect control protein and plants with the fully modified cryIA(b) had a 100-fold higher level of CryIA(b) protein compared with the wild-type gene. Similar results were obtained with the fully modified cryIA(c) gene in plants. Specific sequences of the partially modified cryIA(b) gene were analyzed for their ability to affect cryIA(b) gene expression in tobacco. The DNA sequence of a single region was identified as important to the improvement of plant expression of the cryIA(b) gene. The increased levels of cryIA(b) mRNA were not directly proportional to the increased levels of CryIA(b) protein in plants transformed with the modified cryIA(b) genes, indicating that the nucleotide sequence of these genes had an effect in improving their translational efficiency in plants.

Insect resistant cotton plants.

Abstract: We have expressed truncated forms of the insect control protein genes of Bacillus thuringiensis var. kurstaki HD-1(cryIA(b) and HD-73 (cryIA(c) in cotton plants at levels that provided effective control of agronomically important lepidopteran insect pests. Total protection from insect damage of leaf tissue from these plants was observed in laboratory assays when tested with two lepidopteran insects, an insect relatively sensitive to the B.t.k. insect control protein, Trichoplusia ni (cabbage looper) and an insect that is 100 fold less sensitive, Spodoptera exigua (beet armyworm). Whole plants, assayed under conditions of high insect pressure with Heliothis zea (cotton bollworm) showed effective square and boll protection. Immunological analysis of the cotton plants indicated that the insect control protein represented 0.05% to 0.1% of the total soluble protein. We view these results as a major step towards the agricultural use of genetically modified plants with insect resistance in this valuable, high acreage crop.

Insect Tolerant Transgenic Tomato Plants

Abstract: The structure of an insect control protein gene from Bacillus thuringiensis var. kurstaki HD–1 was determined, and truncated forms of the gene that express a functional insecticidal protein were generated. Two of these truncated genes were incorporated into a plant expression vector for Agrobacterium–mediated transformation. Transgenic tomato plants containing the chimeric genes express the insect control protein gene. Such expression confers tolerance to lepidopteran larvae on the transgenic tomato plants and their progeny. These engineered tomato plants represent a significant step to increased selectivity, specificity and efficiency in insect control.

Production of transgenic soybean plants using Agrobacterium-mediated DNA transfer.

Abstract: Transgenic soybean plants have been produced using an Agrobacterium-mediated gene transfer system. This procedure relied on a regeneration protocol in which shoot organogenesis was induced on cotyledons of soybean genotypes selected for susceptibility to Agrobacterium. Cotyledon explants were inoculated with Agrobacterium tumefaciens pTiT37-SE harboring pMON9749 (conferring kanamycin resistance and β-glucuronidase “GUS” activity) or pTiT37-SE∷pMON894 (conferring kanamycin resistance and glyphosate tolerance) and cultured on shoot induction medium containing kanamycin. Plantlets were tested for gene insertion 3–4 months post-inoculation. Approximately 6% of the shoots (8 plants to date) produced on the kanamycin-selected cotyledons were transgenic based on assays for GUS expression, kanamycin resistance or glyphosate tolerance. Progeny from two of these plants demonstrated co-segregation of kanamycin resistance and either GUS expression or glyphosate tolerance in a 3:1 ratio indicating a single insert inherited in a Mendelian fashion.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Climate Change 2007: Impacts, Adaptation and Vulnerability.

Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

Bacillus thuringiensis and Its Pesticidal Crystal Proteins

Abstract: During the past decade the pesticidal bacterium Bacillus thuringiensis has been the subject of intensive research. These efforts have yielded considerable data about the complex relationships between the structure, mechanism of action, and genetics of the organism’s pesticidal crystal proteins, and a coherent picture of these relationships is beginning to emerge. Other studies have focused on the ecological role of the B. thuringiensis crystal proteins, their performance in agricultural and other natural settings, and the evolution of resistance mechanisms in target pests. Armed with this knowledge base and with the tools of modern biotechnology, researchers are now reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.