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Abstract Background Dysbiotic gut microbiome, genetically predisposed or chemically disrupted, has been linked with insulin-dependent diabetes (IDD) including autoimmune type 1 diabetes (T1D) in both humans and animal models. However, specific IDD-inducing gut bacteria remain to be identified and their casual role in disease development demonstrated via experiments that can fulfill Koch’s postulates. Results Here, we show that novel gut pathobionts in the Muribaculaceae family, enriched by a low-dose dextran sulfate sodium (DSS) treatment, translocated to the pancreas and caused local inflammation, beta cell destruction and IDD in C57BL/6 mice. Antibiotic removal and transplantation of gut microbiota showed that this low DSS disrupted gut microbiota was both necessary and sufficient to induce IDD. Reduced butyrate content in the gut and decreased gene expression levels of an antimicrobial peptide in the pancreas allowed for the enrichment of selective members in the Muribaculaceae family in the gut and their translocation to the pancreas. Pure isolate of one such members induced IDD in wildtype germ-free mice on normal diet either alone or in combination with normal gut microbiome after gavaged into stomach and translocated to pancreas. Potential human relevance of this finding was shown by the induction of pancreatic inflammation, beta cell destruction and IDD development in antibiotic-treated wildtype mice via transplantation of gut microbiome from patients with IDD including autoimmune T1D. Conclusion The pathobionts that are chemically enriched in dysbiotic gut microbiota are sufficient to induce insulin-dependent diabetes after translocation to the pancreas. This indicates that IDD can be mainly a microbiome-dependent disease, inspiring the need to search for novel pathobionts for IDD development in humans. Video Abstract

Abstract Background Decrease in anthocyanin content results in the loss of red color in leaves, petals and receptacles during development. The content of anthocyanin was affected by the biosynthesis and degradation of anthocyanin. Compared with the known detailed mechanism of anthocyanin biosynthesis, the degradation mechanism is not fully investigated. It is vital to study the degradation mechanism of anthocyanin in pear for promoting the accumulation of anthocyanin and inhibiting the red fading in pear. Results Here, we reported that laccase encoded by PbLAC4-like was associated with anthocyanin degradation in pear. The expression pattern of PbLAC4-like was negatively correlated with the content of anthocyanin during the color fading process of pear leaves, petals and receptacles. Phylogenetic analysis and sequence alignment revealed that PbLAC4-like played a vital role in anthocyanin degradation. Thus, the degradation of anthocyanin induced by PbLAC4-like was further verified by transient assays and prokaryotic expression. More than 80% of anthocyanin compounds were degraded by transiently over-expressed PbLAC4-like in pear fruitlet peel. The activity of crude enzyme to degrade anthocyanin in leaves at different stages was basically consistent with the expression of PbLAC4-like. The anthocyanin degradation ability of prokaryotic induced PbLAC4-like protein was also verified by enzyme activity assay. Besides, we also identified PbMYB26 as a positive regulator of PbLAC4-like. Yeast one-hybrid and dual luciferase assay results showed that PbMYB26 activated PbLAC4-like expression by directly binding to the PbLAC4-like promoter. Conclusions Taken together, the PbLAC4-like activated by PbMYB26, was involved in the degradation of anthocyanin, resulting in the redness fading in different pear tissues.

Abstract Background Parthenocarpy results in traits attractive to both consumers and breeders, and it overcomes the obstacle of self-incompatibility in the fruit set of horticultural crops, including pear (Pyrus bretshneider). However, there is limited knowledge regarding the genetic and molecular mechanisms that regulate parthenogenesis. Results Here, in a transcriptional comparison between pollination-dependent fruit and GA4-induced parthenocarpy, PbCYP78A6 was identified and proposed as a candidate gene involved in parthenocarpy. PbCYP78A6 is similar to Arabidopsis thaliana CYP78A6 and highly expressed in pear hypanthia. The increased PbCYP78A6 expression, as assessed by RT-qPCR, was induced by pollination and GA4 exposure. The ectopic overexpression of PbCYP78A6 contributed to parthenocarpic fruit production in tomato. The PbCYP78A6 expression coincided with fertilized and parthenocarpic fruitlets development and the expression of fruit development-related genes as assessed by cytological observations and RT-qPCR, respectively. PbCYP78A6 RNA interference and overexpression in pear calli revealed that the gene is an upstream regulator of specific fruit development-related genes in pear. Conclusions Our findings indicate that PbCYP78A6 plays a critical role in fruit formation and provide insights into controlling parthenocarpy.

Abstract Background For bioethanol production from lignocellulosic biomass, phenolics derived from pretreatment have been generally considered as highly inhibitory towards enzymatic hydrolysis and fermentation. As phenolics are produced from lignin degradation during pretreatment, it is likely that the pretreatment will exert a strong impact on the structure of phenolics, resulting in varied levels of inhibition of the bioconversion process. Despite the extensive studies on pretreatment, it remains unclear how pretreatment process affects the properties of generated phenolics and how the inhibitory effect of phenolics from different pretreatment varies on enzymatic hydrolysis and fermentation. Results In this study, the structural properties of phenolic compounds derived from four typical pretreatment [dilute acid (DA), liquid hot water pretreatment (LHW), ammonia fiber expansion (AFEX) and alkaline pretreatment (AL)] were characterized, and their effect on both enzymatic hydrolysis and fermentation were evaluated. The inhibitory effect of phenolics on enzymatic hydrolysis followed the order: AFEX > LHW > DA > AL, while the inhibitory effect of phenolics on Zymomonas mobilis 8b strain fermentation followed the order: AL > LHW > DA > AFEX. Interestingly, this study revealed that phenolics derived from AFEX showed more severe inhibitory effect on enzymatic hydrolysis than those from the other pretreatments at the same phenolics concentrations (note: AFEX produced much less amount of phenolics compared to AL and DA), while they exhibited the lowest inhibitory effect on fermentation. The composition of phenolics from different pretreatments was analyzed and model phenolics were applied to explore the reason for this difference. The results suggested that the amide group in phenolics might account for this difference. Conclusions Pretreatment process greatly affects the properties of generated phenolics and the inhibitory effects of phenolics on enzymatic hydrolysis and fermentation. This study provides new insight for further pretreatment modification and hydrolysate detoxification to minimize phenolics-caused inhibition and enhance the efficiency of enzymatic hydrolysis and fermentation.

Abstract Background The aim of this study was to investigate the correlation of the dual energy CT measured iodine concentration and total iodine content with blood measured thyroid parameters. Methods Forty-three patients with normal thyroid function at our hospital from August 2017 to October 2019 were included in this retrospective study. Dual energy CT was used to scan the neck of thyroid patients. The mean iodine concentration and thyroid tissue volume were measured to calculate the total iodine content of the thyroid. Relevant tests of triiodothyronine (FT3), total triiodothyronine (TT3), total thyroxine (TT4), free thyroxine (FT4), and thyroid hormone (TSH) were conducted. The correlation of the thyroid mean iodine concentration and total iodine content with blood-measured thyroid function was analysed. Result The total iodine content in the thyroid was positively correlated with FT3 but negatively correlated with TSH. The mean iodine concentration of the thyroid was positively correlated with both FT3 and TT3. Conclusion The thyroid iodine content measured by dual energy CT can be used to determine the human iodine nutritional status and evaluate thyroid function, which will facilitate the diagnosis and treatment of thyroid diseases.

Abstract Background As a class of natural antioxidants in plants, fruit flavonol metabolites are beneficial to human health. However, the regulatory networks for flavonol biosynthesis in most fruits are largely unknown. Previously, we reported a spontaneous pear bud sport ‘Red Zaosu’ (Pyrus bretschneideri Rehd.) with a high flavonoid content in its fruit. The identification of the flavonol biosynthetic regulatory network in this mutant pear fruit is crucial for elucidating the flavonol biosynthetic mechanism in fruit. Results Here, we demonstrated the PbMYB12b positively regulated flavonols biosynthesis in ‘Red Zaosu’ fruit. Initially, we investigated the accumulation patterns of four major quercetin glycosides and two major isorhamnetin glycosides in the fruit of ‘Red Zaosu’ and its wild-type ‘Zaosu’. A PRODUCTION OF FLAVONOL GLYCOSIDES (PFG)-type MYB transcription factor PbMYB12b was also screened for because of its correlation with flavonol accumulation in pear fruit. The biofunction of PbMYB12b was verified by transient overexpression and RNAi assays in pear fruit and young leaves. Overexpression of PbMYB12b enhanced the biosynthesis of quercetin glycosides and isorhamnetin glycosides by positively regulating a general flavonoids biosynthesis gene PbCHSb and a flavonol biosynthesis gene PbFLS. This finding was also supported by dual-luciferase transient expression assay and transient β-glucuronidase (GUS) reporter assay. Conclusions Our study indicated that PbMYB12b positively regulated flavonol biosynthesis, including four major quercetin glycosides and two major isorhamnetin glycosides, by promoting the expression of PbCHSb and PbFLS in pear fruit.

Abstract Lignin is the most abundant aromatic substrate on Earth and its valorization technologies are still under developed. Depolymerization and fragmentation are the predominant preparatory strategies for valorization of lignin to chemicals and fuels. However, due to the structural heterogeneity of lignin, depolymerization and fragmentation typically result in diverse product species, which require extensive separation and purification procedures to obtain target products. For lignin valorization, bacterial-based systems have attracted increasing attention because of their diverse metabolisms, which can be used to funnel multiple lignin-based compounds into specific target products. Here, recent advances in lignin valorization using bacteria are critically reviewed, including lignin-degrading bacteria that are able to degrade lignin and use lignin-associated aromatics, various associated metabolic pathways, and application of bacterial cultures for lignin valorization. This review will provide insight into the recent breakthroughs and future trends of lignin valorization based on bacterial systems.

Abstract Background Although various pre-treatment methods have been developed to disrupt the structure of lignocellulosic biomass, high dosage of cellulases is still required to hydrolyze lignocellulose to fermentable sugars. Enzyme recycling via recycling unhydrolyzed solids after enzymatic hydrolysis is a promising strategy to reduce enzyme loading for production of cellulosic ethanol. Results To develop effective enzyme recycling method via recycling unhydrolyzed solids, this work investigated both enzymatic hydrolysis kinetics and enzyme adsorption kinetics on dilute acid and dilute alkali pre-treated corn stover (CS). It was found that most of the hydrolysable biomass was hydrolyzed in the first 24 h and about 40% and 55% of the enzymes were adsorbed on unhydrolyzed solids for dilute alkali-CS and dilute acid-CS, respectively, at 24 h of enzymatic hydrolysis. Lignin played a significant role in such adsorption and lignin materials derived from dilute acid-CS and dilute alkali-CS possessed different enzyme adsorption properties. Enzyme recycling was performed by recycling unhydrolyzed solids after 24 h enzymatic hydrolysis for five successive rounds, and successfully reduced 40% and 50% of the enzyme loadings for hydrolysis of dilute alkali-CS and for hydrolysis of dilute acid-CS, respectively. Conclusions This study presents that the enzymes adsorbed on the unhydrolyzed solids after short-time hydrolysis could be recycled effectively for efficient enzymatic hydrolysis. Lignin derived from dilute acid-CS has higher enzyme adsorption capacity than the lignin derived from dilute alkali-CS, which led to more enzymes recycled. By applying the enzyme recycling strategy developed in this study, the enzyme dosage needed for effective cellulose hydrolysis can be significantly reduced.

Following publication of the original article [1], the authors reported an error in Fig. 3 and Table 2.