Sulforaphane modulates the expression of Cyp6a2 and Cyp6g1 in larvae of the ST and HB crosses of the Drosophila wing spot test and is genotoxic in the ST cross.

Constitutive overexpression of Cyp6g1 and Cyp6a2 genes in DDT-resistant line Oregon-flare of the Drosophila melanogaster wing spot test (SMART) has been reported. Cyp6g1 and Cyp6a2 expression levels were compared against the ß-actin gene in the standard (ST) and high bioactivation (HB) crosses of the Somatic Mutation and Recombination test (SMART) treated with sulforaphane or phenobarbital as the control inductor. The CYP450s' enzymatic activity was determined by overall NADH consumption. The expression levels of both genes and the CYP450s activity was higher in the HB cross. The Cyp6g1 levels were higher than those of Cyp6a2 in both crosses, but lower than the expression of ß-actin. Sulforaphane decreased Cyp6g1 in the HB cross and increased it in the ST cross; Cyp6a2 expression was inhibited in the ST cross. Sulforaphane resulted mutagenic in the ST cross, which could be related to the inhibition of Cyp6a2. Phenobarbital did not modify the Cyp6g1 levels but increased the Cyp6a2 and CYP450s basal activity. Although the transcript levels were always higher in the HB cross than in the ST, the expression of Cyp6a2 and Cyp6g1 was not constitutive and was independent one from the other. Sulforaphane modulated both genes in a differential way in each cross and, in contrast to its putative protective effect, it resulted to be mutagenic.

First Report of a Geminivirus Inducing Yellow Mottle in Okra (Abelmoschus esculentus) in Mexico.

Okra is an annual vegetable species native to Africa. In Mexico, the states of Tamaulipas, Guerrero, and Morelos contain the most important okra-producing areas. Viral-like diseases have recently affected the fruit production. In the field, the most common symptoms encountered include yellow streak, distortion of fruits, and foliar yellow mottle. Total DNA extracts from symptomatic okra plants were used as a template for polymerase chain reaction (PCR)-based detection using begomovirus-specific primers. RepMot and CPMot primers (1) were used for the amplification of DNA fragments that included the Rep and coat protein (CP) genes of begomoviruses. PCR results suggested the presence of a begomovirus in symptomatic plants. Southern and dot blot hybridization analysis were performed using a DNA fragment containing the CP gene of Pepper huasteco virus as a probe. Hybridization conducted under low stringency conditions confirmed the presence of a geminivirus. Additionally, transmission by grafting and biolistic (total DNA extracts from symptomatic plants) inoculations induced consistently severe streak fruits and yellow mottle symptoms in okra plants. Cloning of the PCR products (approximately 632-bp fragment) was performed in the PCRTopo vector (Invitrogen, San Diego, CA). Cloned viral inserts were sequenced (Genbank Accession No. AF349113). Nucleotide sequence comparisons were performed using the Clustal Method (MegAlign, DNAStar software, Madison, WI) with the GenBank database. Analysis of the PCR products confirmed the begomovirus nature of the sequence. The first 64 amino acids of the CP had 89% identity with Squash leaf curl virus while the intergenic region had 85% identity with Sida golden mosaic virus. To our knowledge, this is the first report of a begomovirus infecting okra in Mexico. Reference: 1) J. T. Ascencio et al. Plant Dis. 86:692, 2002.