ABSTRACT
@#The mechanism of insecticide resistance is traditionally attributed to detoxification enzymes, target site alteration, decreased penetration of insecticides and behavioural resistance. Other form of mechanisms, such as the role of protein(s) in resistance is unknown. In the present study, the protein profiling of both IMR-PSS strain (permethrin-selected) and IMR-LS strain (laboratory-susceptible) 24 hours post exposure period to permethrin was carried out via 1D-gel electrophoresis and liquid chromatography mass spectrometry (LC-MS/ MS). The bands which appeared in the gel of 1D-electrophoresis revealed an abundance of proteins. The band pattern of both strains looked macroscopically alike and differed only in band intensity. However, LC-MS/MS analysis revealed that the IMR-PSS strain produced extra 388 peptides that were not found in the IMR-LS strain, indicating that IMR-PSS strain reacted differently from IMR-LS strain as a result of persistent exposure to permethrin. Since the complex banding patterns of 1D-gel electrophoresis were difficult to interpret the significance of the protein difference between IMR-PSS and IMR-LS strain, hence LC-MS/MS analysis is ideally suited for better protein resolution and thus will allow more in-depth comparison of the complex pattern. The findings here provide the first preliminary evidence that insecticide resistance in mosquito induces up regulation of proteins that may be protective to mosquitoes against insecticide and proteins could be another mechanism that contributes to development of resistance.
ABSTRACT
Phytoplankton was assessed quantitatively and qualitatively in regard to their abundance in the northern part of El-Umum drain, west of Alexandria at four stations to study the spatial, temporal, dominance and abundance of the phytoplankton community. The samples were collected monthly from April 2003 to April 2004. A total of 152 phytoplankton taxa were identified belonging to Bacillariophyceae (60), Chlorophyceae (46), Cyanophyceae (20), Euglenophyceae (17) and Dinophyceae (9). A limited number of these were recorded throughout the year, and showed an indication of organic pollution. The total densities (333.8x103units l-1) were mainly a reflection of the trends in counts of Bacillariophyceae and Chlorophyceae (138.1 x 103 and 131.6 x 103 units l-1, respectively). Monthly differences in the quantitative (18 x 103 to 1645 x 103 units l-1) and qualitative composition ( 41 to 113 taxa) of the phytoplankton communities in the different stations were marked, with recurrent high abundance in spring (910.4 x103 units l-1), whereas lowest densities occurred in autumn (99.7x103 units l-1). Cyanophyceae was most abundant in July (67.5 x103 units l-1), whereas Euglenophyceae in December (32.0x103 units l-1). Species diversity (H’) gave a signal of the area is light to moderate polluted. The present study emphasized the need to use phytoplankton community as index of water quality.