Two strains of Pseudomonas fluorescens bacteria differentially affect survivorship of waxworm (Galleria mellonella) larvae exposed to an arthropod fungal pathogen,Beauveria bassiana

Two strains of Pseudomonas fluorescens were found contaminating a biopesticide used in a previous study against Varroa destructor infestations in honey bee hives. In that study, the biopesticide, a formulation of a fungal pathogen of arthropods, Beauveria bassiana, failed to have any negative impact on the mite infestation despite successful results in previous studies using uncontaminated batches of the same biopesticide. The objective of the present research was to determine whether the bacteria may have interfered with the infectivity and/or virulence of B. bassiana in a simplified system; positive results in that system would then provide a rationale for further work under more complex conditions. Galleria mellonella late instar larvae treated topically with both a bacterial suspension of 6.8 to 7.0×10⁷ cfu/ml and a fungal suspension of 2.5×10⁷ or 2.5×10⁸ B. bassiana conidia/ml showed, in the case of one of the bacterial strains, significantly increased survivorship compared to larvae treated with just the B. bassiana suspension. When larvae were immersed in a bacterial suspension prior to application of B. bassiana suspension using a spray tower, a significant positive effect of the same P. fluorescens strain on larval survivorship was observed at 2.5×10⁸ conidia/ml. Neither the bacterial suspensions alone nor blank control solutions had any effect on larval survivorship. These results show that an interaction between the bacteria and the pathogen may explain some of the results from the prior field trial.     

Inhibition of mitochondrial fusion by α‐synuclein is rescued by PINK1, Parkin and DJ‐1

Aggregation of α‐synuclein (αS) is involved in the pathogenesis of Parkinson's disease (PD) and a variety of related neurodegenerative disorders. The physiological function of αS is largely unknown. We demonstrate with in vitro vesicle fusion experiments that αS has an inhibitory function on membrane fusion. Upon increased expression in cultured cells and in Caenorhabditis elegans, αS binds to mitochondria and leads to mitochondrial fragmentation. In C. elegans age‐dependent fragmentation of mitochondria is enhanced and shifted to an earlier time point upon expression of exogenous αS. In contrast, siRNA‐mediated downregulation of αS results in elongated mitochondria in cell culture. αS can act independently of mitochondrial fusion and fission proteins in shifting the dynamic morphologic equilibrium of mitochondria towards reduced fusion. Upon cellular fusion, αS prevents fusion of differently labelled mitochondrial populations. Thus, αS inhibits fusion due to its unique membrane interaction. Finally, mitochondrial fragmentation induced by expression of αS is rescued by coexpression of PINK1, parkin or DJ‐1 but not the PD‐associated mutations PINK1 G309D and parkin Δ1–79 or by DJ‐1 C106A.     

Correction to: Experimental evidence of minimal effects on octocoral hosts caused by the introduced ophiuroid Ophiothela mirabilis

Coral Reefs - A correction to this paper has been published: https://doi.org/10.1007/s00338-021-02110-0     

L1 is sequentially processed by two differently activated metalloproteases and presenilin/gamma-secretase and regulates neural cell adhesion, cell migration, and neurite outgrowth

The immunoglobulin superfamily recognition molecule L1 plays important functional roles in the developing and adult nervous system. Metalloprotease-mediated cleavage of this adhesion molecule has been shown to stimulate cellular migration and neurite outgrowth. We demonstrate here that L1 cleavage is mediated by two distinct members of the disintegrin and metalloprotease family, ADAM10 and ADAM17. This cleavage is differently regulated and leads to the generation of a membrane bound C-terminal fragment, which is further processed through gamma-secretase activity. Pharmacological approaches with two hydroxamate-based inhibitors with different preferences in blocking ADAM10 and ADAM17, as well as loss of function and gain of function studies in murine embryonic fibroblasts, showed that constitutive shedding of L1 is mediated by ADAM10 while phorbol ester stimulation or cholesterol depletion led to ADAM17-mediated L1 cleavage. In contrast, N-methyl-d-aspartate treatment of primary neurons stimulated ADAM10-mediated L1 shedding. Both proteases were able to affect L1-mediated adhesion and haptotactic migration of neuronal cells. In particular, both proteases were involved in L1-dependent neurite outgrowth of cerebellar neurons. Thus, our data identify ADAM10 and ADAM17 as differentially regulated L1 membrane sheddases, both critically affecting the physiological functions of this adhesion protein.     

5-Fluoro-4-thiouridine phosphoramidite: new synthon for introducing photoaffinity label into oligodeoxynucleotides

The synthesis of phosphoramidite of 5-fluoro-4-thio-2'-O-methyluridine is described. An appropriate set of protecting groups was optimized including the 4-thio function introduced via 4-triazolyl as the 4-(2-cyanoethyl)thio derivative, and the t-butyldimethyl silyl for 2' and 3' hydroxyl protection, enabling efficient synthesis of the phosphoramidite. These protecting groups prevented unwanted side reactions during oligonucleotide synthesis. The utility of the proposed synthetic route was proven by the preparation of several oligonucleotides via automated synthesis. Photochemical experiments confirmed the utility of the synthon.     

Intratumoral expression of IL-17 and its prognostic role in gastric adenocarcinoma patients

In this study, we characterized the intratumoral expression of IL-17 and CD8(+) TILs in gastric adenocarcinoma patients after resection and determined the correlation between the survival probability of gastric adenocarcinoma patients and the expression of IL-17 in tumor. Expression of IL-17 and CD8 was assessed by immunohistochemistry, and the prognostic effects of intratumoral IL-17 expression and CD8(+) TILs were evaluated by Cox regression and Kaplan-Meier analysis. Immunohistochemical detection revealed the presence of IL-17 and CD8(+) cells in gastric adenocarcinoma tissue samples (90.6%, 174 out of 192 patients and 96.9%, 186 out of 192 patients, respectively). We have also found that intratumoral IL-17 expression was significantly correlated with age (p=0.004) and that the number of CD8(+)TILs was significantly correlated with UICC staging (p=0.012) and the depth of tumor invasion (p=0.022). The five-year overall survival probability among patients intratumorally expressing higher levels of IL-17 was significantly better than those expressing lower levels of IL-17 (p=0.036). Multivariate Cox proportional hazard analyses revealed that intratumoral IL-17 expression (HR: 0.521; 95% CI: 0.329-0.823; p=0.005) was an independent factor affecting the five-year overall survival probability. We conclude that low levels of intratumoral IL-17 expression may indicate poor prognosis in gastric adenocarcinoma patients.