Gut microbiota controls the development of chronic pancreatitis:A critical role of short-chain fatty acids-producing Gram-positive bacteria

Chronic pancreatitis(CP)is a progressive and irreversible fibroinflammatory disorder,accompanied by pancreatic exocrine insufficiency and dysregulated gut microbiota.Recently,accumulating evidence has supported a correlation between gut dysbiosis and CP development.However,whether gut microbiota dysbiosis contributes to CP pathogenesis remains unclear.Herein,an experimental CP was induced by repeated high-dose caerulein injections.The broad-spectrum antibiotics(ABX)and ABX targeting Gram-positive(G+)or Gram-negative bacteria(G-)were applied to explore the specific roles of these bacteria.Gut dysbiosis was observed in both mice and in CP patients,which was accompanied by a sharply reduced abundance for short-chain fatty acids(SCFAs)-producers,especially G+bacteria.Broad-spectrum ABX exacerbated the severity of CP,as evidenced by aggravated pancreatic fibrosis and gut dysbiosis,especially the depletion of SCFAs-producing G+bacteria.Additionally,depletion of SCFAs-producing G+bacteria rather than G-bacteria intensified CP progression independent of TLR4,which was attenuated by supplementation with exogenous SCFAs.Finally,SCFAs modulated pancreatic fibrosis through inhibition of macrophage infiltration and M2 phenotype switching.The study supports a critical role for SCFAs-producing G+bacteria in CP.Therefore,modulation of dietary-derived SCFAs or G+SCFAs-producing bacteria may be considered a novel interventive approach for the management of CP.

Further insight into reproductive incompatibility between putative cryptic species of the Bemisia tabaci whitefly complex

The whitefly Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae）, with its global distribution and extensive genetic diversity, is now known to be a complex of over 35 cryptic species. However, a satisfactory resolution of the systematics of this species complex is yet to be achieved. Here, we designed experiments to examine reproductive compatibility among species with different levels of mitochondrial cytochrome oxidase I （mtCOI） divergence. The data show that putative species with mtCOI divergence of 〉 8% between them consistently exhibited complete reproductive isolation. However, two of the putative species, Asia II 9 and Asia II 3, with mtCOI divergence of 4.47% between them, exhibited near complete reproductive compatibility in one direction of their cross, and partial reproductive compatibility in the other direction. Together with some recent reports on this topic from the literature, our data indicates that, while divergence in the mtCOI sequences provides a valid molecular marker for species delimitation in most clades, more genetic markers and more sophisticated molecular phylogeny will be required to achieve adequate delimitation of all species in this whitefly complex. While many attempts have been made to examine the reproductive compatibility among genetic groups of the B. tabaci complex, our study represents the first effort to conduct crossing experiments with putative species that were chosen with considerations of their genetic divergence. In light of the new data, we discuss the best strategy and protocols to conduct further molecular phylogenetic analysis and crossing trials, in order to reveal the overall pattern of reproductive incompatibility among species of this whitefly complex.