Eicosanoids mediate Galleria mellonella immune response to hemocoel injection of entomopathogenic nematode cuticles.

Entomopathogenic nematodes are symbiotically associated with bacteria and widely used in biological control of insect pests. The interference of symbiotic bacteria with insect host immune responses is fairly well documented. However, knowledge of mechanisms regulating parasite­host interactions still remains fragmentary. In this study, we used nematode (Steinernema carpocapsae and Heterorhabditis bacteriophora) cuticles and Galleria mellonella larvae as parasite­host model, focused on the changes of innate immune parameters of the host in the early phase of nematode cuticle infection and investigated the role of eicosanoid biosynthesis pathway in the process. The results showed that injection of either S. carpocapsae or H. bacteriophora cuticles into the larval hemocoel both resulted in significant decreases in the key innate immune parameters (e.g., hemocyte density, microaggregation, phagocytosis and encapsulation abilities of hemocyte, and phenoloxidase and antibacterial activities of the cell-free hemolymph). Our study indicated that the parasite cuticles could actively suppress the innate immune response of the G. mellonella host. We also found that treating G. mellonella larvae with dexamethasone and indomethacin induced similar depression in the key innate immune parameters to the nematode cuticles. However, these effects were reversed when dexamethasone, indomethacin, or nematode cuticles were injected together with arachidonic acid. Additionally, we found that palmitic acid did not reverse the influence of the dexamethasone, indomethacin, or nematode cuticles on the innate immune responses. Therefore, we inferred from our results that both S. carpocapsae and H. bacteriophora cuticles inhibited eicosanoid biosynthesis to induce host immunodepression.

Novel porphyrin-daunomycin hybrids: synthesis and preferential binding to G-quadruplexes over i-motif.

Encouraged by the enormous importance attributed to the structure and function of human telomeric DNA, herein we focused our attention on the interaction of a serious of newly prepared porphyrin-daunomycin (Por-DNR) hybrids with the guanine-rich single-strand oligomer (G4) and the complementary cytosine-rich strand (i-motif). Various spectral methods such as absorption and fluorescence titration, surface-enhanced Raman and circular dichroism spectrum were integrated in the experiment and it was found that these Por-DNR hybrids could serve as prominent molecules to recognize G4 and i-motif. What is more, interesting results were obtained that the hybrids with longer flexible links are more favorable in binding with both G4 and i-motif than the hybrid with shorter linkage. These Por-DNR hybrids may help to develop new ideas in the research of human telomeric DNA with small molecules.

Numerical solution of an inverse diffraction grating problem from phaseless data.

This paper is concerned with the numerical solution of an inverse diffraction grating problem, which is to reconstruct a periodic grating profile from measurements of the phaseless diffracted field at a constant height above the grating structure. An efficient continuation method is developed to recover the Fourier coefficients of the periodic grating profile. The continuation proceeds along the wavenumber and updates are obtained from the Landweber iteration at each step. Numerical results are presented to show that the method can effectively reconstruct the shape of the grating profile.