Mitochondrial DNA and TLR9 drive muscle inflammation upon Opa1 deficiency

Opa1 participates in inner mitochondrial membrane fusion and cristae morphogenesis. Here, we show that muscle‐specific Opa1 ablation causes reduced muscle fiber size, dysfunctional mitochondria, enhanced Fgf21, and muscle inflammation characterized by NF‐κB activation, and enhanced expression of pro‐inflammatory genes. Chronic sodium salicylate treatment ameliorated muscle alterations and reduced the muscle expression of Fgf21. Muscle inflammation was an early event during the progression of the disease and occurred before macrophage infiltration, indicating that it is a primary response to Opa1 deficiency. Moreover, Opa1 repression in muscle cells also resulted in NF‐κB activation and inflammation in the absence of necrosis and/or apoptosis, thereby revealing that the activation is a cell‐autonomous process and independent of cell death. The effects of Opa1 deficiency on the expression NF‐κB target genes and inflammation were absent upon mitochondrial DNA depletion. Under Opa1 deficiency, blockage or repression of TLR9 prevented NF‐κB activation and inflammation. Taken together, our results reveal that Opa1 deficiency in muscle causes initial mitochondrial alterations that lead to TLR9 activation, and inflammation, which contributes to enhanced Fgf21 expression and to growth impairment.     

Characterization of three monoclonal antibodies which induce and modulate superoxide anion generation in guinea pig macrophages

Three monoclonal antibodies (Ab), termed KY 12, KY 22, and KY 25 and raised against guinea pig macrophages, induced superoxide anion (O2-) generation in the cells. Although each monoclonal Ab bound to macrophages, each had a different pattern of binding to other cell types. In response to each of the Ab, the amount of O2- generated by 5 X 10(5) macrophages was between 0.5 and 0.7 nmol/min and was augmented threefold to fivefold by the addition of F(ab')2 fragments of rabbit Abs to mouse Ig. When macrophages were pretreated with soluble immune complexes (I.C.) prior to stimulation by the monoclonal Ab, the O2- generation stimulated by KY 12 or KY 22 was reduced by more than 70%. In contrast, pretreatment of macrophages with I.C. did not reduce O2- generation in response to KY 25. KY 12 and KY 22 stimulated adenyl cyclase activity in macrophages, but KY 25 did not. Pretreatment of the cells with soluble I.C. did not interfere with the enhancing effect of the monoclonal Ab on adenyl cyclase activity. Pretreatment of macrophages with KY 12 reduced by over 60% of subsequent generation of O2- in response to wheat germ agglutinin, I.C., formyl-methionyl-leucyl-phenylalanine, phorbol myristate acetate, KY 22, or KY 25. KY 22 or KY 25 did not suppress the generation of O2- in response to other stimuli. These results suggest that KY 22 and KY 25 activate O2- generation in a manner that differs from that of KY 12. These monoclonal Ab should prove useful in examining the regulation of O2- production.     

Stereochemical aspects of the conversion of cyclopeptine into dehydrocyclopeptine by cyclopeptine dehydrogenase from Penicillium cyclopium

Cyclopeptine dehydrogenase, an enzyme from Penicillium cyclopium, catalyses the reversible transformation of the benzodiazepine alkaloids cyclopeptine and dehydrocyclopeptine. By the dehydrogenation of cyclopeptine two hydrogen atoms are removed from the positions 3 and 10. It was demonstrated that, from the two optical isomers of cyclopeptine, only the naturally occurring 3S-compound was used as substrate by cyclopeptine dehydrogenase. To test the stereospecificity of the enzyme with respect to the second hydrogen which is eliminated from C-10 a mixture of cyclopeptine-3S-[10R-³H₁] and cyclopeptine-3R-10S-³H₁] was prepared. The 3S-isomer was transformed by the enzyme into radioactively labelled dehydrocyclopeptine. This demonstrated that cyclopeptine dehydrogenase removes the 10-proS hydrogen atom from the cyclopeptine molecule. Because the formed dehydrocyclopeptine has the trans-configuration it is probable that a synperiplanar elimination takes place. The hydride ion removed from cyclopeptine is transferred to the 4-proR-position of NAD⁺. Cyclopeptine dehydrogenase thus belongs to the A-specific dehydrogenases.     

The vitamin requirements of Candida shehatae for xylose fermentation

Abstract The vitamin requirements of a strain of Candida shehatae for the fermentation of d -xylose was determined using a statistical procedure with a 2³ factorial design. Biotin as well as thiamine exerted a dramatic stimulatory effect on the rate of ethanol production, coupled with a significant improvement in the ethanol yield. The greatest enhancement of the fermentation was found in the presence of both these vitamins. Pyridoxine exerted only a minor effect, but was essential for complete substrate utilization in the absence of either biotin or thiamine. Only biotin caused a significant increase in the growth rate.     

Molecular dynamics simulation in vacuo and in solution of cyclolinopeptide A: a conformational study.

The conformation of cyclolinopeptide A [c-(Pro-Pro-Phe-Phe-Leu-Ile-Ile-Leu-Val)], a naturally occurring peptide with remarkable cytoprotective activity, has been investigated by means of molecular dynamics simulations in various molecular environments. Structural and dynamical properties have been analyzed and compared with those experimentally determined. A detailed analysis of hydrogen bonds is reported.     

Rehydration conditions and viability of freeze-dried lactic acid bacteria

The influence of rehydration conditions on the recovery of 16 species of freeze-dried lactic acid bacteria was investigated. The survival of dried cultures during reconstitution to the wet state was increased by rehydration with small volumes of the medium used for that purpose (0.3 and 0.5 ml). Comparison of rehydration at several times of exposure showed best survival at 10 min for the majority of the species analyzed.