Phlebotomus papatasi Antimicrobial Peptides in Larvae and Females and a Gut-Specific Defensin Upregulated by Leishmania major Infection

Phlebotomus papatasi is the vector of Leishmania major, causing cutaneous leishmaniasis in the Old World. We investigated whether P. papatasi immunity genes were expressed toward L. major, commensal gut microbes, or a combination of both. We focused on sand fly transcription factors dorsal and relish and antimicrobial peptides (AMPs) attacin and defensin and assessed their relative gene expression by qPCR. Sand fly larvae were fed food with different bacterial loads. Relish and AMPs gene expressions were higher in L3 and early L4 larval instars, while bacteria 16S rRNA increased in late L4 larval instar, all fed rich-microbe food compared to the control group fed autoclaved food. Sand fly females were treated with an antibiotic cocktail to deplete gut bacteria and were experimentally infected by Leishmania. Compared to non-infected females, dorsal and defensin were upregulated at early and late infection stages, respectively. An earlier increase of defensin was observed in infected females when bacteria recolonized the gut after the removal of antibiotics. Interestingly, this defensin gene expression occurred specifically in midguts but not in other tissues of females and larvae. A gut-specific defensin gene upregulated by L. major infection, in combination with gut-bacteria, is a promising molecular target for parasite control strategies.

Inheritance of NmDef02 synthetic defensin gene and hpt selectable marker in four successive generations of transgenic rice (Oryza sativa, cv. J-104)

The evaluation of the inheritance and stability of the transgenes is essential for the application of transgenic plants in agriculture. In this work, we studied the inheritance of two transgenes in T1, T2, T3 and T4 rice progenies. Transgenic rice plants (cv. J-104) was obtained by biolistic method using a synthetic defensin gene (NmDef02) and hpt as selectable marker gene, co-transformed in a 4:1 proportion, respectively. Regenerated plants were acclimated under natural conditions. The study started from the primary transformants that fulfilled the agronomic characters reported by the experts for the J-104 rice cultivar in the maturation stage. The integration and relative expression of NmDef02 in T1 plants was verified by Southern blot and qRT-PCR, respectively. The inheritance of transgenes over four generations was analyzed by PCR. The following transgene combinations were identified: NmDef02(+)hpt(+), NmDef02(+)hpt(-) and NmDef02(-)hpt(-). The most advantageous combination was NmDef02(+)hpt(-), which corresponded to the marker-free plants harboring the gene of interest. The inheritance of NmDef02 was confirmed in T1 and T2 progenies, but in some T3 and T4 lines the loss of this gene was verified. This inheritance analysis provided information concerning the transgenic population, but the mechanisms that destabilize the inheritance of the gene of interest will be the goal of future research.