Maternal and developmental toxicity after exposure to formulation of chlorothalonil and thiophanate-methyl during organogenesis in rats.

Chlorothalonil and thiophanate-methyl are fungicides widely used in agriculture. The aim of this study was to assess maternal toxicity and embryotoxic potential of exposure to chlorothalonil and thiophanate-methyl during organogenesis period in rats. Pregnant rats were divided into four groups: control and exposed to 400 (CT400), 800 (CT800) and 1200 mg-1kg bw-1 day (CT1200) of commercial formulation constituted of 200 g of thiophanate-methyl kg-1 and 500 g of chlorothalonil kg-1 by gavage, from 6th to 15th gestational day. Maternal toxicity, liver, kidney and placenta histology, reproductive performance, and external, skeletal and visceral malformations of fetuses were evaluated. Maternal liver weight was decreased in CT1200 group and focal necrosis and microvesicular steatosis, inflammatory infiltrate and hepatocytes with pyknotic nucleus were observed in CT800 and CT1200 groups. Reproductive performance was similar among groups. The percentage of fetuses small for pregnancy age was increase in CT400 and CT800 groups. Moreover, incidence of skeletal anomalies was increased in the three groups exposed to fungicides. Chlorothalonil and thiophanate-methyl exposure showed affect the prenatal development and induce maternal toxicity.

Surface-enhanced resonance raman scattering: single-molecule detection in a Langmuir-Blodgett monolayer.

Surface-enhanced resonance Raman scattering (SERRS) is used for single-molecule detection from spatially resolved 1-microm2 sections of a Langmuir-Blodgett (LB) monolayer deposited onto a Ag film. The target molecule, bis (benzimidazo) thioperylene (BZP), is dispersed in an arachidic acid monomolecular layer containing one BZP molecule per microm2, which is also the probing area of the Raman microscope. For concentrated samples (attomole quantities in the field of view), average SERRS, surface-enhanced fluorescence (SEF), and Raman imaging, including line mapping and global images at different temperatures, were recorded. Single-molecule SERRS spectra, obtained using an LB monolayer, present changes in bandwidth and relative intensities, highlighting the properties of single-molecule SERRS that are lost in average SERRS measurements of mixed LB monolayers obtained at the same temperatures. Also, the dilute system phenomenon of blinking is discussed with regard to results obtained from LB monolayers. The dilution process used in the single-molecule LB SERRS work is independently supported by fluorescence results obtained from very dilute solutions with monomer concentrations down to 10(-12) M.