Sublethal effects of abamectin on the biological performance of the predatory mite, <Emphasis Type="Italic">Phytoseius plumifer</Emphasis> (Acari: Phytoseiidae)

Traditionally estimating pesticide effects by measuring only lethal effect may underestimate the total negative effect on beneficial arthropods and sublethal effects should be assessed to estimate the total effect of their applications. In this study, sublethal effect of the acaricide abamectin (Vermectin^® 1.8% EC, Giah, Iran) on the predatory mite Phytoseius plumifer (Canestrini &; Fanzago) (Acari: Phytoseiidae) fed on Tetranychus urticae Koch was assessed in laboratory conditions. The adult predators were exposed to the residues of the acaricide on fig leaves and the LC₅₀ value was determined based on a concentration–response analysis. The results showed that sublethal concentrations (LC₁₀, LC₂₀ and LC₃₀) of abamectin severely affected the fecundity and longevity of the treated females of P. plumifer. Furthermore, reproductive and life table parameters of the subsequent generation were affected. The results indicated that adverse effects of abamectin on population growth of P. plumifer were significant, so the results from this study can be used to develop approximate guidelines for the use of abamectin in order to minimize their impact on P. plumifer and related natural enemies.     

Impact of Protein Domains on PE_PGRS30 Polar Localization in Mycobacteria

PE_PGRS proteins are unique to the Mycobacterium tuberculosis complex and a number of other pathogenic mycobacteria. PE_PGRS30, which is required for the full virulence of M. tuberculosis (Mtb), has three main domains, i.e. an N-terminal PE domain, repetitive PGRS domain and the unique C-terminal domain. To investigate the role of these domains, we expressed a GFP-tagged PE_PGRS30 protein and a series of its functional deletion mutants in different mycobacterial species (Mtb, Mycobacterium bovis BCG and Mycobacterium smegmatis) and analysed protein localization by confocal microscopy. We show that PE_PGRS30 localizes at the mycobacterial cell poles in Mtb and M. bovis BCG but not in M. smegmatis and that the PGRS domain of the protein strongly contributes to protein cellular localization in Mtb. Immunofluorescence studies further showed that the unique C-terminal domain of PE_PGRS30 is not available on the surface, except when the PGRS domain is missing. Immunoblot demonstrated that the PGRS domain is required to maintain the protein strongly associated with the non-soluble cellular fraction. These results suggest that the repetitive GGA-GGN repeats of the PGRS domain contain specific sequences that contribute to protein cellular localization and that polar localization might be a key step in the PE_PGRS30-dependent virulence mechanism.     

Efficient programming of human eye conjunctiva-derived induced pluripotent stem (ECiPS) cells into definitive endoderm-like cells

Due to pluripotency of induced pluripotent stem (iPS) cells, and the lack of immunological incompatibility and ethical issues, iPS cells have been considered as an invaluable cell source for future cell replacement therapy. This study was aimed first at establishment of novel iPS cells, ECiPS, which directly reprogrammed from human Eye Conjunctiva-derived Mesenchymal Stem Cells (EC-MSCs); second, comparing the inductive effects of Wnt3a/Activin A biomolecules to IDE1 small molecule in derivation of definitive endoderm (DE) from the ECiPS cells. To that end, first, the EC-MSCs were transduced by SOKM-expressing lentiviruses and characterized for endogenous expression of embryonic markers Then the established ECiPS cells were induced to DE formation by Wnt3a/Activin A or IDE1. Quantification of GSC, Sox17 and Foxa2 expression, as DE-specific markers, in both mRNA and protein levels revealed that induction of ECiPS cells by either Wnt3a/Activin A or IDE1 could enhance the expression level of the genes; however the levels of increase were higher in Wnt3a/Activin A induced ECiPS-EBs than IDE1 induced cells. Furthermore, the flow cytometry analyses showed no synergistic effect between Activin A and Wnt3a to derive DE-like cells from ECiPS cells. The comparative findings suggest that although both Wnt3a/Activin A signaling and IDE1 molecule could be used for differentiation of iPS into DE cells, the DE-inducing effect of Wnt3a/Activin A was statistically higher than IDE1.