Enhancement of 2,3-butanediol production from Jerusalem artichoke tuber extract by a recombinant <Emphasis Type="Italic">Bacillus</Emphasis> sp. strain BRC1 with increased inulinase activity

A Bacillus sp. strain named BRC1 is capable of producing 2,3-butanediol (2,3-BD) using hydrolysates of the Jerusalem artichoke tuber (JAT), a rich source of the fructose polymer inulin. To enhance 2,3-BD production, we undertook an extensive analysis of the Bacillus sp. BRC1 genome, identifying a putative gene (sacC) encoding a fructan hydrolysis enzyme and characterizing the activity of the resulting recombinant protein expressed in and purified from Escherichia coli. Introduction of the sacC gene into Bacillus sp. BRC1 using an expression vector increased enzymatic activity more than twofold. Consistent with this increased enzyme expression, 2,3-BD production from JAT was also increased from 3.98 to 8.10 g L^?1. Fed-batch fermentation of the recombinant strain produced a maximal level of 2,3-BD production of 28.6 g L^?1, showing a high theoretical yield of 92.3%.     

Control of the pericentrosomal H2O2 level by peroxiredoxin I is critical for mitotic progression

Proteins associated with the centrosome play key roles in mitotic progression in mammalian cells. The activity of Cdk1-opposing phosphatases at the centrosome must be inhibited during early mitosis to prevent premature dephosphorylation of Cdh1—an activator of the ubiquitin ligase anaphase-promoting complex/cyclosome—and the consequent premature degradation of mitotic activators. In this paper, we show that reversible oxidative inactivation of centrosome-bound protein phosphatases such as Cdc14B by H₂O₂ is likely responsible for this inhibition. The intracellular concentration of H₂O₂ increases as the cell cycle progresses. Whereas the centrosome is shielded from H₂O₂ through its association with the H₂O₂-eliminating enzyme peroxiredoxin I (PrxI) during interphase, the centrosome-associated PrxI is selectively inactivated through phosphorylation by Cdk1 during early mitosis, thereby exposing the centrosome to H₂O₂ and facilitating inactivation of centrosome-bound phosphatases. Dephosphorylation of PrxI by okadaic acid–sensitive phosphatases during late mitosis again shields the centrosome from H₂O₂ and thereby allows the reactivation of Cdk1-opposing phosphatases at the organelle.     

Expression of mosquitocidal crystal protein genes in non-insecticidal Bacillus thuringiensis subsp. israelensis

Bacillus thuringiensis NTB-1 isolated from soil samples in Korea produces ovoidal parasporal inclusions with proteins of approximately 24–40 kDa in size. Although serological study indicated that the isolate has a flagella (H) antigen identical with subsp. israelensis , it seemed to be non-insecticidal against Lepidoptera and Coleoptera as well as Diptera. To investigate the activity of non-insecticidal B. thuringiensis transformed with insecticidal crystal protein genes, cryIVD and cytA genes of B. thuringiensis subsp. morrisoni PG-14, highly toxic to mosquito larvae, were introduced into the isolate NTB-1. The expression of mosquitocidal crystal protein genes in NTB-1 was characterized by SDS–PAGE analysis and electron microscopy. The results showed that crystalline inclusions of host, CryIVD and CytA were stably expressed in the transformant. However, the mosquitocidal activity of transformant was similar to that of B. thuringiensis subsp. kurstaki Cry⁻ B harbouring cryIVD and cytA genes, demonstrating that a synergistic effect by an interaction of both introduced insecticidal and resident non-insecticidal crystal proteins was not observed.     

Novel Interaction of the Z-DNA Binding Domain of Human ADAR1 with the Oncogenic c-Myc Promoter G-Quadruplex

Both G-quadruplex and Z-DNA can be formed in G-rich and repetitive sequences on genome, and their formation and biological functions are controlled by specific proteins. Z-DNA binding proteins, such as human ADAR1, have a highly conserved Z-DNA binding domain having selective affinity to Z-DNA. Here, our study identifies the Z-DNA binding domain of human ADAR1 (hZα_ADAR1) as a novel G-quadruplex binding protein that recognizes c-myc promoter G-quadruplex formed in NHEIII₁ region and represses the gene expression. An electrophoretic migration shift assay shows the binding of hZα_ADAR1 to the intramolecular c-myc promoter G-quadruplex-forming DNA oligomer. To corroborate the binding of hZα_ADAR1 to the G-quadruplex, we conducted CD and NMR chemical shift perturbation analyses. CD results indicate that hZα_ADAR1 stabilizes the parallel-stranded conformation of the c-myc G-quadruplex. The NMR chemical shift perturbation data reveal that the G-quadruplex binding region in hZα_ADAR1 was almost identical with the Z-DNA binding region. Finally, promoter assay and Western blot analysis show that hZα_ADAR1 suppresses the c-myc expression promoted by NHEIII₁ region containing the G-quadruplex-forming sequence. This finding suggests a novel function of Z-DNA binding protein as a regulator of G-quadruplex-mediated gene expression.     

Large‐scale gene expression reveals different adaptations of Hyalopterus persikonus to winter and summer host plants

Host alternation, an obligatory seasonal shifting between host plants of distant genetic relationship, has had significant consequences for the diversification and success of the superfamily of aphids. However, the underlying molecular mechanism remains unclear. In this study, the molecular mechanism of host alternation was explored through a large‐scale gene expression analysis of the mealy aphid Hyalopterus persikonus on winter and summer host plants. More than four times as many unigenes of the mealy aphid were significantly upregulated on summer host Phragmites australis than on winter host Rosaceae plants. In order to identify gene candidates related to host alternation, the differentially expressed unigenes of H. persikonus were compared to salivary gland expressed genes and secretome of Acyrthosiphon pisum. Genes involved in ribosome and oxidative phosphorylation and with molecular functions of heme–copper terminal oxidase activity, hydrolase activity and ribosome binding were potentially upregulated in salivary glands of H. persikonus on the summer host. Putative secretory proteins, such as detoxification enzymes (carboxylesterases and cytochrome P450s), antioxidant enzymes (peroxidase and superoxide dismutase), glutathione peroxidase, glucose dehydrogenase, angiotensin‐converting enzyme, cadherin, and calreticulin, were highly expressed in H. persikonus on the summer host, while a SCP GAPR‐1‐like family protein and a salivary sheath protein were highly expressed in the aphids on winter hosts. These results shed light on phenotypic plasticity in host utilization and seasonal adaptation of aphids.     

Probiotic roles of Lactobacillus sp. in swine: insights from gut microbiota

The use of lactobacilli as probiotics in swine has been gaining attention due to their ability to improve growth performance and carcass quality, prevent gastrointestinal infection and most importantly, their ‘generally recognized as safe’ status. Previous studies support the potential of lactobacilli to regulate host immune systems, enhance gut metabolic capacities and maintain balance in the gut microbiota. Research on swine gut microbiota has revealed complex gut microbial community structure and showed the importance of Lactobacillus to the host's health. However, the species‐ and strain‐specific characteristics of lactobacilli that confer probiotic benefits are still not well understood. The diversity of probiotic traits in a complex gut ecosystem makes it challenging to infer the relationships between specific functions of Lactobacillus sp. and host health. In this review, we provide an overview of how lactobacilli play a pivotal role in the swine gut ecosystem and identify key characteristics that influence gut microbial community structure and the health of pigs. In addition, based on recent and ongoing meta‐omics and omics research on the gut microbiota of pigs, we suggest a workflow combining culture‐dependent and culture‐independent approaches for more effective selection of probiotic lactobacilli.     

A novel pH‐controlled hydrogen sulfide donor protects gastric mucosa from aspirin‐induced injury

Hydrogen sulphide (H₂S) serves as a vital gastric mucosal defence under acid condition. Non‐steroidal anti‐inflammatory drugs (NSAIDs) are among widely prescribed medications with effects of antipyresis, analgesia and anti‐inflammation. However, their inappropriate use causes gastric lesions and endogenous H₂S deficiency. In this work, we reported the roles of a novel pH‐controlled H₂S donor (JK‐1) in NSAID‐related gastric lesions. We found that JK‐1 could release H₂S under mild acidic pH and increase solution pH value. Intragastrical administration of aspirin (ASP), one of NSAIDs, to mice elicited significant gastric lesions, evidenced by mucosal festering and bleeding. It also led to infiltration of inflammatory cells and resultant releases of IL‐6 and TNF‐α, as well as oxidative injury including myeloperoxidase (MPO) induction and GSH depletion. In addition, the ASP administration statistically inhibited H₂S generation in gastric mucosa, while up‐regulated cyclooxygenase (COX)‐2 and cystathionine gamma lyase (CSE) expression. Importantly, these adverse effects of ASP were prevented by the intragastrical pre‐administration of JK‐1. However, JK‐1 alone did not markedly alter the property of mouse stomachs. Furthermore, in vitro cellular experiments showed the exposure of gastric mucosal epithelial (GES‐1) cells to HClO, imitating MPO‐driven oxidative injury, decreased cell viability, increased apoptotic rate and damaged mitochondrial membrane potential, which were reversed by pre‐treatment with JK‐1. In conclusion, JK‐1 was proved to be an acid‐sensitive H₂S donor and could attenuate ASP‐related gastric lesions through reconstruction of endogenous gastric defence. This work indicates the possible treatment of adverse effects of NSAIDs with pH‐controlled H₂S donors in the future.