Dothistroma pini,a forest pathogen,contains homologs of aflatoxin biosynthetic pathway genes

Homologs of aflatoxin biosynthetic genes have been identified in the pine needle pathogen Dothistroma pini. D. pini produces dothistromin, a difuranoanthraquinone toxin with structural similarity to the aflatoxin precursor versicolorin B. Previous studies with purified dothistromin suggest a possible role for this toxin in pathogenicity. By using an aflatoxin gene as a hybridization probe, a genomic D. pini clone was identified that contained four dot genes with similarity to genes in aflatoxin and sterigmatocystin gene clusters with predicted activities of a ketoreductase (dotA), oxidase (dotB), major facilitator superfamily transporter (dotC), and thioesterase (dotD). A D. pini dotA mutant was made by targeted gene replacement and shown to be severely impaired in dothistromin production, confirming that dotA is involved in dothistromin biosynthesis. Accumulation of versicolorin A (a precursor of aflatoxin) by the dotA mutant confirms that the dotA gene product is involved in an aflatoxin-like biosynthetic pathway. Since toxin genes have been found to be clustered in fungi in every case analyzed so far, it is speculated that the four dot genes may comprise part of a dothistromin biosynthetic gene cluster. A fifth gene, ddhA, is not a homolog of aflatoxin genes and could be at one end of the dothistromin cluster. These genes will allow comparative biochemical and genetic studies of the aflatoxin and dothistromin biosynthetic pathways and may also lead to new ways to control Dothistroma needle blight.     

Agrobacterium-mediated transformation of cauliflower: optimization of protocol and development of Bt-transgenic cauliflower

A number of factors that are known to influence genetic transformation were evaluated to optimizeAgrobacterium-mediated transformation of hypocotyl explants of cauliflower variety Pusa Snowball K-1. The binary vector p35SGUSINT mobilized intoAgrobacterium strain GV2260 was used for transformation and transient GUS expression was used as the basis for identifying the most appropriate conditions for transformation. Explant age, preculture period, bacterial strain and density were found to be critical determinants of transformation efficiency. Using the optimized protocol, the syntheticcryIA(b) gene was mobilized into cauliflower. Molecular analyses of transgenics established the integration and expression of the transgene. Insect bioassays indicated the effectiveness of the transgene against infestation by diamondback moth (Plutella xylostella) larvae.     

Phospholipase A2-activating protein--an important regulatory molecule in modulating cyclooxygenase-2 and tumor necrosis factor production during inflammation

Inflammation is a complex multifactorial process and a hallmark of many inflammatory diseases. Most of the tissue destruction that occurs in these diseases is the result of an aberrant or often uncontrolled immune response. Factors that play an important role in such diseases include pro-inflammatory cytokines, complement, and eicosanoids. This review focuses on eicosanoids and their regulation via phospholipase A2-activating protein, which could be targeted as a new therapeutic tool to control inflammatory diseases.     

Loss of caveolin-1 gene expression accelerates the development of dysplastic mammary lesions in tumor-prone transgenic mice

Caveolin-1 is the principal structural component of caveolae microdomains, which represent a subcompartment of the plasma membrane. Several independent lines of evidence support the notion that caveolin-1 functions as a suppressor of cell transformation. For example, the human CAV-1 gene maps to a suspected tumor suppressor locus (D7S522/7q31.1) that is frequently deleted in a number of carcinomas, including breast cancers. In addition, up to 16% of human breast cancers harbor a dominant-negative mutation, P132L, in the CAV-1 gene. Despite these genetic associations, the tumor suppressor role of caveolin-1 still remains controversial. To directly assess the in vivo transformation suppressor activity of the caveolin-1 gene, we interbred Cav-1 (-/-) null mice with tumor-prone transgenic mice (MMTV-PyMT) that normally develop multifocal dysplastic lesions throughout the entire mammary tree. Herein, we show that loss of caveolin-1 gene expression dramatically accelerates the development of these multifocal dysplastic mammary lesions. At 3 wk of age, loss of caveolin-1 resulted in an approximately twofold increase in the number of lesions (foci per gland; 3.3 +/- 1.0 vs. 7.0 +/- 1.2) and an approximately five- to sixfold increase in the total area occupied by these lesions. Similar results were obtained at 4 wk of age. However, complete loss of caveolin-1 was required to accelerate the appearance of these dysplastic mammary lesions, because Cav-1 (+/-) heterozygous mice did not show any increases in foci development. We also show that loss of caveolin-1 increases the extent and the histological grade of these mammary lesions and facilitates the development of papillary projections in the mammary ducts. Finally, we demonstrate that cyclin D1 expression levels are dramatically elevated in Cav-1 (-/-) null mammary lesions, consistent with the accelerated appearance and growth of these dysplastic foci. This is the first in vivo demonstration that caveolin-1 can function as a transformation suppressor gene.     

Consumption of tomato products with olive oil but not sunflower oil increases the antioxidant activity of plasma

Health benefits of lycopene from tomato products have been suggested to be related to its antioxidant activity. Dietary fat may influence the absorption and hence the plasma levels and antioxidant activity of lycopene. In the present study, we have compared the effect of consumption of tomato products with extra-virgin olive oil vs. tomato products plus sunflower oil on plasma lycopene and antioxidant levels. Results show that the oil composition does not affect the absorption of lycopene from tomato products because similar levels of plasma lycopene (mean +/- SD) were obtained on feeding tomatoes (providing approximately 46 mg lycopene/d) for 7 d with either olive oil (0.66 +/- 0.26 vs 1.20 +/- 0.20 micromol/l, p <.002) or sunflower oil (0.67 +/- 0.27 vs. 1.14 micromol/l, p <.001). However, consumption of tomato products with olive oil significantly raised the plasma antioxidant activity (FRAP) from 930 +/- 150 to 1118 +/- 184 micromol/l, p <.01) but no effect was observed when the sunflower oil was used. The change (supplementation minus start values) in FRAP following the consumption of tomato products with oil was significantly higher for olive oil (190 +/- 101) than for sunflower oil (-9.6 +/- 99, p <. 005). In conclusion, the results of the study show that consumption of tomato products with olive oil but not with sunflower oil improves the antioxidant activity of the plasma.