Maternal inheritance of glucose intolerance via oocyte TET3 insufficiency.

Diabetes mellitus is prevalent among women of reproductive age, and many women are left undiagnosed or untreated1. Gestational diabetes has profound and enduring effects on the long-term health of the offspring2,3. However, the link between pregestational diabetes and disease risk into adulthood in the next generation has not been sufficiently investigated. Here we show that pregestational hyperglycaemia renders the offspring more vulnerable to glucose intolerance. The expression of TET3 dioxygenase, responsible for 5-methylcytosine oxidation and DNA demethylation in the zygote4, is reduced in oocytes from a mouse model of hyperglycaemia (HG mice) and humans with diabetes. Insufficient demethylation by oocyte TET3 contributes to hypermethylation at the paternal alleles of several insulin secretion genes, including the glucokinase gene (Gck), that persists from zygote to adult, promoting impaired glucose homeostasis largely owing to the defect in glucose-stimulated insulin secretion. Consistent with these findings, mouse progenies derived from the oocytes of maternal heterozygous and homozygous Tet3 deletion display glucose intolerance and epigenetic abnormalities similar to those from the oocytes of HG mice. Moreover, the expression of exogenous Tet3 mRNA in oocytes from HG mice ameliorates the maternal effect in offspring. Thus, our observations suggest an environment-sensitive window in oocyte development that confers predisposition to glucose intolerance in the next generation through TET3 insufficiency rather than through a direct perturbation of the oocyte epigenome. This finding suggests a potential benefit of pre-conception interventions in mothers to protect the health of offspring.

An intellectual disability-related MED23 mutation dysregulates gene expression by altering chromatin conformation and enhancer activities.

Transcriptional Mediator controls diverse gene programs for various developmental and pathological processes. The human Mediator MED23/R617Q mutation was reported in a familial intellectual disability (ID) disorder, although the underlying mechanisms remain poorly understood. Constructed by gene editing, the Med23/R617Q knock-in mutant mice exhibited embryonic lethality due to the largely reduced Med23/R617Q protein level, but the R617Q mutation in HEK293T cells didn't change its expression and incorporation into Mediator Complex. RNA-seq revealed that MED23/R617Q mutation disturbed gene expression, related to neural development, learning and memory. Specifically, R617Q mutation reduced the MED23-dependent activities of ELK1 and E1A, but in contrast, upregulated the MAPK/ELK1-driven early immediate genes (IEGs) JUN and FOS. ChIP-seq and Hi-C revealed that the MED23 R617Q mutation reprogramed a subset of enhancers and local chromatin interactions, which correlated well with the corresponding gene expression. Importantly, the enhancers and chromatin interactions surrounding IEGs were unchanged by the R617Q mutation, but DACH1, an upstream repressor of IEGs, showed reduced enhancer-promoter interactions and decreased expression in mutant cells, thus relieving its inhibition to the intellectual-related IEGs. Overall, unraveling the MED23-DACH1-IEG axis provides a mechanistic explanation for the effects of the MED23/R617Q mutation on gene dysregulation and inherited ID.

Structural and molecular basis for urea recognition by Prochlorococcus.

Nitrogen (N) is an essential element for microbial growth and metabolism. The growth and reproduction of microorganisms in more than 75% of areas of the ocean are limited by N. Prochlorococcus is numerically the most abundant photosynthetic organism on the planet. Urea is an important and efficient N source for Prochlorococcus. However, how Prochlorococcus recognizes and absorbs urea still remains unclear. Prochlorococcus marinus MIT 9313, a typical Cyanobacteria, contains an ABC-type transporter, UrtABCDE, which may account for the transport of urea. Here, we heterologously expressed and purified UrtA, the substrate-binding protein of UrtABCDE, detected its binding affinity toward urea, and further determined the crystal structure of the UrtA/urea complex. Molecular dynamics simulations indicated that UrtA can alternate between "open" and "closed" states for urea binding. Based on structural and biochemical analyses, the molecular mechanism for urea recognition and binding was proposed. When a urea molecule is bound, UrtA undergoes a state change from open to closed surrounding the urea molecule, and the urea molecule is further stabilized by the hydrogen bonds supported by the conserved residues around it. Moreover, bioinformatics analysis showed that ABC-type urea transporters are widespread in bacteria and probably share similar urea recognition and binding mechanisms as UrtA from P. marinus MIT 9313. Our study provides a better understanding of urea absorption and utilization in marine bacteria.

Divergent projections of the prelimbic cortex mediate autism- and anxiety-like behaviors.

The comorbidity of autism spectrum disorder and anxiety is common, but the underlying circuitry is poorly understood. Here, Tmem74-/- mice showed autism- and anxiety-like behaviors along with increased excitability of pyramidal neurons (PNs) in the prelimbic cortex (PL), which were reversed by Tmem74 re-expression and chemogenetic inhibition in PNs of the PL. To determine the underlying circuitry, we performed conditional deletion of Tmem74 in the PNs of PL of mice, and we found that alterations in the PL projections to fast-spiking interneurons (FSIs) in the dorsal striatum (dSTR) (PLPNs-dSTRFSIs) mediated the hyperexcitability of FSIs and autism-like behaviors and that alterations in the PL projections to the PNs of the basolateral amygdaloid nucleus (BLA) (PLPNs-BLAPNs) mediated the hyperexcitability of PNs and anxiety-like behaviors. However, the two populations of PNs in the PL had different spatial locations, optogenetic manipulations revealed that alterations in the activity in the PL-dSTR or PL-BLA circuits led to autism- or anxiety-like behaviors, respectively. Collectively, these findings highlight that the hyperactivity of the two populations of PNs in the PL mediates autism and anxiety comorbidity through the PL-dSTR and PL-BLA circuits, which may lead to the development of new therapeutics for the autism and anxiety comorbidity.

Marinobacter qingdaonensis sp. nov., a moderately halotolerant bacterium isolated from intertidal sediment.

A Gram-stain-negative, aerobic, rod-shaped and halotolerant bacterium, designated as strain ASW11-75T, was isolated from intertidal sediments in Qingdao, PR China, and identified using a polyphasic taxonomic approach. Growth of strain ASW11-75T occurred at 10-45 °C (optimum, 37 °C), pH 6.5-9.0 (optimum, pH 8.0) and 0.5-18.0 % NaCl concentrations (optimum, 2.5 %). Phylogenetic analyses based on 16S rRNA gene sequences and 1179 single-copy orthologous clusters indicated that strain ASW11-75T is affiliated with the genus Marinobacter. Strain ASW11-75T showed highest 16S rRNA gene sequence similarity to 'Marinobacter arenosus' CAU 1620T (98.5 %). The digital DNA-DNA hybridization and average nucleotide identity values between strain ASW11-75T and its closely related strains (Marinobacter salarius R9SW1T, Marinobacter similis A3d10T, 'Marinobacter arenosus' CAU 1620T, Marinobacter sediminum R65T, Marinobacter salinus Hb8T, Marinobacter alexandrii LZ-8T and Marinobacter nauticus ATCC 49840T) were 19.8-24.5 % and 76.6-80.7 %, respectively. The predominant cellular fatty acids were C16 : 0, C18 : 1 ω9c and C16 : 0 N alcohol. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified aminophospholipid and two unidentified lipids. The major isoprenoid quinone was ubiquinone-9. The genomic DNA G+C content was 62.2 mol%. Based on genomic and gene function analysis, strain ASW11-75T had lower protein isoelectric points with higher ratios of acidic residues to basic residues and possessed genes related to ion transport and organic osmoprotectant uptake, implying its potential tolerance to salt. The results of polyphasic characterization indicated strain ASW11-75T represents a novel Marinobacter species, for which the name Marinobacter qingdaonensis sp. nov. with the type strain ASW11-75T is proposed. The type strain is ASW11-75T (=KCTC 82497T=MCCC 1K05587T).

Alteromonas arenosi sp. nov., a novel bioflocculant-producing bacterium, isolated from intertidal sand.

A novel Gram-stain-negative, strictly aerobic and bioflocculant-producing bacterium, designated as ASW11-36T, was isolated from an intertidal sand collected from coastal areas of Qingdao, PR China. Growth occurred at 15-40 °C (optimum, 30 °C), pH 7.0-9.0 (optimum, pH 7.5) and with 1.5-7.0% (w/v) NaCl (optimum, 2.5-3.0%). In the whole-cell fatty acid pattern prevailed C16:0 and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c). The major isoprenoid quinone was determined to be Q-8 and the major polar lipids were phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), one unidentified aminolipid (AL), one unidentified glycolipid (GL), and two lipids (L1, L2). Based on the phylogenetic analyses of 16S rRNA gene sequences and 618 single-copy orthologous clusters, strain ASW11-36T could represent a novel member of the genus Alteromonas and was closely related to Alteromonas flava P0211T (98.4%) and Alteromonas facilis P0213T (98.3%). The pairwise average nucleotide identity and digital DNA-DNA hybridization values of the ASW11-36T genome assembly against the closely related species genomes were 71.8% and 21.7%, respectively, that clearly lower than the proposed thresholds for species. Based on phenotypic, phylogenetic, and chemotaxonomic analyses, strain ASW11-36T is considered to represent a novel species of the genus Alteromonas, for which the name Alteromonas arenosi sp. nov. is proposed. The type strain is ASW11-36T (= KCTC 82496T = MCCC 1K05585T). In addition, the strain yielded 65% of flocculating efficiency in kaolin suspension with CaCl2 addition. The draft genome of ASW11-36T shared abundant putative CAZy family related genes, especially involved in the biosynthesis of exopolysaccharides, implying its potential environmental and biological applications.

Cost-effective production of alginate oligosaccharides from Laminaria japonica roots by Pseudoalteromonas agarivorans A3.

BACKGROUND: Alginate oligosaccharides (AOs) are the degradation products of alginate, a natural polysaccharide abundant in brown algae. AOs generated by enzymatic hydrolysis have diverse bioactivities and show broad application potentials. AOs production via enzymolysis is now generally with sodium alginate as the raw material, which is chemically extracted from brown algae. In contrast, AOs production by direct degradation of brown algae is more advantageous on account of its cost reduction and is more eco-friendly. However, there have been only a few attempts reported in AOs production from direct degradation of brown algae. RESULTS: In this study, an efficient Laminaria japonica-decomposing strain Pseudoalteromonas agarivorans A3 was screened. Based on the secretome and mass spectrum analyses, strain A3 showed the potential as a cell factory for AOs production by secreting alginate lyases to directly degrade L. japonica. By using the L. japonica roots, which are normally discarded in the food industry, as the raw material for both fermentation and enzymatic hydrolysis, AOs were produced by the fermentation broth supernatant of strain A3 after optimization of the alginate lyase production and hydrolysis parameters. The generated AOs mainly ranged from dimers to tetramers, among which trimers and tetramers were predominant. The degradation efficiency of the roots reached 54.58%, the AOs production was 33.11%, and the AOs purity was 85.03%. CONCLUSION: An efficient, cost-effective and green process for AOs production directly from the underutilized L. japonica roots by using strain A3 was set up, which differed from the reported processes in terms of the substrate and strain used for fermentation and the AOs composition. This study provides a promising platform for scalable production of AOs, which may have application potentials in industry and agriculture.

Enhanced ammonia sensing response based on Pt-decorated Ti3C2Tx/TiO2composite at room temperature.

Herein, we report a Pt-decorated Ti3C2Tx/TiO2gas sensor for the enhanced NH3sensing response at room temperature. Firstly, the TiO2nanosheets (NSs) arein situgrown onto the two-dimensional (2D) Ti3C2Txby hydrothermal treatment. Similar to Ti3C2Txsensor, the Ti3C2Tx/TiO2sensor has a positive resistance variation upon exposure to NH3, but with slight enhancement in response. However, after the loading of Pt nanoparticles (NPs), the Pt-Ti3C2Tx/TiO2sensor shows a negative response with significantly improved NH3sensing performance. The shift in response direction indicates that the dominant sensing mechanism has changed under the sensitization effect of Pt NPs. At room temperature, the response of Pt-Ti3C2Tx/TiO2gas sensor to 100 ppm NH3is about 45.5%, which is 13.8- and 10.8- times higher than those of Ti3C2Txand Ti3C2Tx/TiO2gas sensors, respectively. The experimental detection limit of the Pt-Ti3C2Tx/TiO2gas sensor to detect NH3is 10 ppm, and the corresponding response is 10.0%. In addition, the Pt-Ti3C2Tx/TiO2gas sensor shows the fast response/recovery speed (23/34 s to 100 ppm NH3), high selectivity and good stability. Considering both the response value and the response direction, the corresponding gas-sensing mechanism is also deeply discussed. This work is expected to shed a new light on the development of noble metals decorated MXene-metal oxide gas sensors.

Uterine Anteroposterior Diameter Measured by Transvaginal Sonography is a Predictor for Dysmenorrhea in Patients With and Without Endometriosis: A Pilot Study.

PURPOSE: The aim of this study was to determine the correlation between uterine diameters and menstrual abdominal pain intensity in patients with and without endometriosis (EM), and the independent influence of EM on the pain intensity. METHODS: Uterine diameters and the diagnosis of adenomyosis were ascertained by transvaginal ultrasonography (TVS). Menstrual abdominal pain intensity was estimated by visual analog scale (VAS). Linear regression was used to figure out the impact of uterine diameters and EM on the VAS scores. Logistic regression was used to calculate the correlation between uterine diameters and the diagnosis of adenomyosis. The cutoff values of uterine anteroposterior diameter (AD) to predict dysmenorrhea (VAS ≥ 4) and the diagnosis of adenomyosis were determined by receiver operating characteristic curves. RESULTS: There were 220 patients with and 233 patients without EM included. Uterine AD independently correlated with the VAS scores in patients with (B = .230, P = .000) and without (B = .203, P = .000) EM. A uterine AD of 39.5 mm predicted dysmenorrhea in both groups. The presence of EM increased the VAS scores by 1.151 points when controlling for uterine diameters. Uterine AD also independently correlated with the diagnosis of adenomyosis under TVS in patients with (OR = 1.212, 95% CI = 1.130-1.301; P = .000) and without (OR = 1.192, 95% CI = 1.123-1.263; P = .000) EM. A uterine AD of 38.5 and 39.5 mm predicted the diagnosis of adenomyosis under TVS in patients with and without EM, respectively. CONCLUSIONS: Increased uterine AD, which is probably ascribed to adenomyosis, plays an important role in augmented menstrual abdominal pain intensity. Meanwhile, the presence of EM reinforces the pain.

Biogeography of culturable marine bacteria from both poles reveals that 'everything is not everywhere' at the genomic level.

Based on 16S rRNA gene analyses, the same bacterial operational taxonomic units (OTUs) are common to both the Arctic and Antarctic oceans, supporting the concept 'everything is everywhere'. However, whether the same OTUs from both poles have identical genomes, i.e. whether 'everything is still everywhere' at the genomic level has not yet been examined systematically. Here, we isolated, sequenced and compared the genomes of 45 culturable marine bacteria belonging to three genera of Salinibacterium, Psychrobacter and Pseudoalteromonas from both polar oceans. The bacterial strains with identical 16S rRNA genes were common to both poles in every genus, and four identical genomes were detected in the genus Salinibacterium from the Arctic region. However, no identical genomes were observed from opposite poles in this study. Our data, therefore, suggest that 'everything is not everywhere' at the genomic level. The divergence time between bacteria is hypothesized to exert a strong impact on the bacterial biogeography at the genomic level. The geographical isolation between poles was observed for recently diverged, highly similar genomes, but not for moderately similar genomes. This study thus improves our understanding of the factors affecting the genomic-level biogeography of marine microorganisms isolated from distant locations.

Real-world data analysis of immune checkpoint inhibitors in stage III-IV adenocarcinoma and squamous cell carcinoma.

BACKGROUND: This study was designed to investigate the clinical application, efficacy, and safety of immune checkpoint inhibitors (ICIs) in the treatment of lung cancer in the real world. METHODS: A retrospective, observational analysis was conducted on patients treated with ICIs in four tertiary hospitals in the region from January 2015 to March 2021, to evaluate the clinical efficacy of ICIs single-agent or combined chemotherapy and anti-vascular drugs in the first-line or second-line treatment of patients with lung cancer. RESULTS: Three hundred and fifteen patients were enrolled in this study. In patients with stage III-IV adenocarcinoma and Squamous cell carcinoma, the objective response rate (ORR) and disease control rate (DCR) were 35.5% (87/245) and 93.5% (229/245), respectively, the median progression-free survival (PFS) was 10.8 months, and the median overall survival (OS) was not reached. A total of 132 patients received ICIs as the first-line treatment, the median treatment cycle was 8 cycles (2-20 cycles), the short-term efficacy ORR was 38.6%, DCR was 93.9%, and the median PFS was 11.4 months. One hundred thirteen patients received ICIs treatment as second-line treatment, the median treatment cycle was five cycles (2-10 cycles), the short-term efficacy ORR was 31.9%, DCR was 92.9%, and the median PFS was 10.0 months. There were no statistically significant differences in ORR, DCR, or median PFS with ICIs as the first-line treatment compared with the second-line treatment(P > 0.05). The results of subgroup analysis showed that Eastern Cooperative Oncology Group performance status (ECOG PS), epidermal growth factor receptor (EGFR) mutation status, pathological type and number of treatment lines were not correlated with median PFS(P > 0.05). However, there were statistically significant differences in programmed death-ligand 1(PD-L1) expression, corticosteroid interference, and antibiotic (Abx) treatment among all groups (P < 0.05). In terms of safety, the overall incidence of adverse reactions in 315 patients was 62.5%, and the incidence of immune-related adverse events (irAEs) was 13.7%. Grade 1-2 and 3-4 incidence of adverse events were 34.9 and 27.65%, respectively. There were four patients who experienced fatal irAEs, two cases were liver damage leading to liver failure, one case was immune related pneumonia, and one case was immune related myocarditis. CONCLUSION: In the real world, ICIs has a good effect on patients with lung cancer and significantly improves ORR and PFS.

Structural determination of the lipid A from the deep-sea bacterium Zunongwangia profunda SM-A87: a small-scale approach.

Zunongwangia profunda SM-A87 is a deep-sea sedimentary bacterium from the phylum Bacteroidetes, representing a new genus of Flavobacteriaceae. It was previously investigated for its capability of yielding high quantities of capsular polysaccharides (CPS) with interesting rheological properties, including high viscosity and tolerance to high salinities and temperatures. However, as a Gram-negative, Z. profunda SM-A87 also expresses lipopolysaccharides (LPS) as the main components of the external leaflet of its outer membrane. Here, we describe the isolation and characterization of the glycolipid part of this LPS, i.e. the lipid A, which was achieved by-passing the extraction procedure of the full LPS and by working on the ethanol precipitation product, which contained both the CPS fraction and bacterial cells. To this aim a dual approach was adopted and all analyses confirmed the isolation of Z. profunda SM-A87 lipid A that turned out to be a blend of species with high levels of heterogeneity both in the acylation and phosphorylation pattern, as well as in the hydrophilic backbone composition. Mono-phosphorylated tetra- and penta-acylated lipid A species were identified and characterized by a high content of branched, odd-numbered, and unsaturated fatty acid chains as well as, for some species, by the presence of a hybrid disaccharide backbone.

Halomonas profundi sp. nov., isolated from deep-sea sediment of the Mariana Trench.

Two novel Gram-stain-negative, facultative anaerobic, non-flagellated, rod-shaped bacterial strains, designated MT13T and MT32, were isolated from sediment samples collected from the Mariana Trench at a depth of 8300 m. The two strains grew at -2-30 °C (optimum, 25 °C), at pH 5.5-10.0 (optimum, pH 7.5-8.0) and with 0-15 % (w/v) NaCl (optimum, 3-6 %). They did not reduce nitrate to nitrite nor hydrolyse Tweens 40 and 80, aesculin, casein, starch and DNA. The genomic G+C contents of draft genomes of strain MT13T and MT32 were 52.2 and 54.1 m ol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains MT13T and MT32 were affiliated with the genus Halomonas, with the highest similarity to the type strain of Halomonas olivaria. The values of average nucleotide identity and in silico DNA-DNA hybridization between strain MT13T and MT32, and between strain MT13T and five closely related type strains of Halomonas species indicated that strains MT13T and MT32 belonged to the same species, but represented a novel species in the genus of Halomonas. The major cellular fatty acids of strains MT13T and MT32 were C16 : 0, summed feature 3(C16 : 1 ω7c/ω6c) and summed feature 8 (C18 : 1 ω7c/ω6c). Major polar lipids of strains MT13T and MT32 included phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. Ubiquinone-9 was the predominant respiratory quinone. Based on data from the present polyphasic study, strains MT13T and MT32 represent a novel species of the genus Halomonas, for which the name Halomonas profundi sp. nov. is proposed. The type strain is MT13T (=MCCC 1K06389T=KCTC 82923T).

TET-mediated DNA demethylation controls gastrulation by regulating Lefty-Nodal signalling.

Mammalian genomes undergo epigenetic modifications, including cytosine methylation by DNA methyltransferases (DNMTs). Oxidation of 5-methylcytosine by the Ten-eleven translocation (TET) family of dioxygenases can lead to demethylation. Although cytosine methylation has key roles in several processes such as genomic imprinting and X-chromosome inactivation, the functional significance of cytosine methylation and demethylation in mouse embryogenesis remains to be fully determined. Here we show that inactivation of all three Tet genes in mice leads to gastrulation phenotypes, including primitive streak patterning defects in association with impaired maturation of axial mesoderm and failed specification of paraxial mesoderm, mimicking phenotypes in embryos with gain-of-function Nodal signalling. Introduction of a single mutant allele of Nodal in the Tet mutant background partially restored patterning, suggesting that hyperactive Nodal signalling contributes to the gastrulation failure of Tet mutants. Increased Nodal signalling is probably due to diminished expression of the Lefty1 and Lefty2 genes, which encode inhibitors of Nodal signalling. Moreover, reduction in Lefty gene expression is linked to elevated DNA methylation, as both Lefty-Nodal signalling and normal morphogenesis are largely restored in Tet-deficient embryos when the Dnmt3a and Dnmt3b genes are disrupted. Additionally, a point mutation in Tet that specifically abolishes the dioxygenase activity causes similar morphological and molecular abnormalities as the null mutation. Taken together, our results show that TET-mediated oxidation of 5-methylcytosine modulates Lefty-Nodal signalling by promoting demethylation in opposition to methylation by DNMT3A and DNMT3B. These findings reveal a fundamental epigenetic mechanism featuring dynamic DNA methylation and demethylation crucial to regulation of key signalling pathways in early body plan formation.

Description of Aureibaculum luteum sp. nov. and Aureibaculum flavum sp. nov. isolated from Antarctic intertidal sediments.

Two Gram-stain-negative, aerobic, non-motile, and rod-shaped bacterial strains, designated SM1352T and A20T, were isolated from intertidal sediments collected from King George Island, Antarctic. They shared 99.8% 16S rRNA gene sequence similarity with each other and had the highest sequence similarity of 98.1% to type strain of Aureibaculum marinum but < 93.4% sequence similarity to those of other known bacterial species. The genomes of strains SM1352T and A20T consisted of 5,108,092 bp and 4,772,071 bp, respectively, with the G + C contents both being 32.0%. They respectively encoded 4360 (including 37 tRNAs and 6 rRNAs) and 4032 (including 36 tRNAs and 5 rRNAs) genes. In the phylogenetic trees based on 16S rRNA gene and single-copy orthologous clusters (OCs), both strains clustered with Aureibaculum marinum and together formed a separate branch within the family Flavobacteriaceae. The ANI and DDH values between the two strains and Aureibaculum marinum BH-SD17T were all below the thresholds for species delineation. The major cellular fatty acids (> 10%) of the two strains included iso-C15:0, iso-C15:1 G, iso-C17:0 3-OH. Their polar lipids predominantly included phosphatidylethanolamine, one unidentified aminophospholipid, one unidentified aminolipid, and two unidentified lipids. Genomic comparison revealed that both strains possessed much more glycoside hydrolases and sulfatase-rich polysaccharide utilization loci (PULs) than Aureibaculum marinum BH-SD17T. Based on the above polyphasic evidences, strains SM1352T and A20T represent two novel species within the genus Aureibaculum, for which the names Aureibaculum luteum sp. nov. and Aureibaculum flavum sp. nov. are proposed. The type strains are SM1352T (= CCTCC AB 2014243 T = JCM 30335 T) and A20T (= CCTCC AB 2020370 T = KCTC 82503 T), respectively.

Frame-shifted proteins of a given gene retain the same function.

Frameshift mutations are generally considered to be lethal because it could result in radical changes of the protein sequence behind. However, the protein of frameshift mutants of a type I toxin (ibsc) was found to be still toxic to bacteria, retaining the similar function as wild-type protein to arrest the cellular growth by impairing the membrane's integrity. Additionally, we have verified that this observation is not an individual event as the same phenomenon had been found in other toxins subsequently. After analyzing the coding sequence of these genes, we proposed a hypothesis to search this kind of hidden gene, through which a dihydrofolate reductase-encoding gene (dfrB3) was found out. Like the wild-type reductase, both +1 and -1 frame-shifted proteins of dfrB3 gene were also proved to catalyze the reduction of dihydrofolate to tetrahydrofolate by using NADPH.

Characterization of a Novel Alginate Lyase with Two Alginate Lyase Domains from the Marine Bacterium Vibrio sp. C42.

Alginate is abundant in the cell walls of brown algae. Alginate lyases can degrade alginate, and thus play an important role in the marine carbon cycle and industrial production. Currently, most reported alginate lyases contain only one functional alginate lyase domain. AlyC8 is a putative alginate lyase with two alginate lyase domains (CD1 and CD2) from the marine alginate-degrading strain Vibrio sp. C42. To characterize AlyC8 and its two catalytic domains, AlyC8 and its two catalytic domain-deleted mutants, AlyC8-CD1 and AlyC8-CD2, were expressed in Escherichia coli. All three proteins have noticeable activity toward sodium alginate and exhibit optimal activities at pH 8.0-9.0 and at 30-40 °C, demonstrating that both CD1 and CD2 are functional. However, CD1 and CD2 showed opposite substrate specificity. The differences in substrate specificity and degradation products of alginate between the mutants and AlyC8 demonstrate that CD1 and CD2 can act synergistically to enable AlyC8 to degrade various alginate substrates into smaller oligomeric products. Moreover, kinetic analysis indicated that AlyC8-CD1 plays a major role in the degradation of alginate by AlyC8. These results demonstrate that AlyC8 is a novel alginate lyase with two functional catalytic domains that are synergistic in alginate degradation, which is helpful for a better understanding of alginate lyases and alginate degradation.

A Novel Gelatinase from Marine Flocculibacter collagenilyticus SM1988: Characterization and Potential Application in Collagen Oligopeptide-Rich Hydrolysate Preparation.

Although the S8 family in the MEROPS database contains many peptidases, only a few S8 peptidases have been applied in the preparation of bioactive oligopeptides. Bovine bone collagen is a good source for preparing collagen oligopeptides, but has been so far rarely applied in collagen peptide preparation. Here, we characterized a novel S8 gelatinase, Aa2_1884, from marine bacterium Flocculibacter collagenilyticus SM1988T, and evaluated its potential application in the preparation of collagen oligopeptides from bovine bone collagen. Aa2_1884 is a multimodular S8 peptidase with a distinct domain architecture from other reported peptidases. The recombinant Aa2_1884 over-expressed in Escherichia coli showed high activity toward gelatin and denatured collagens, but no activity toward natural collagens, indicating that Aa2_1884 is a gelatinase. To evaluate the potential of Aa2_1884 in the preparation of collagen oligopeptides from bovine bone collagen, three enzymatic hydrolysis parameters, hydrolysis temperature, hydrolysis time and enzyme-substrate ratio (E/S), were optimized by single factor experiments, and the optimal hydrolysis conditions were determined to be reaction at 60 ℃ for 3 h with an E/S of 400 U/g. Under these conditions, the hydrolysis efficiency of bovine bone collagen by Aa2_1884 reached 95.3%. The resultant hydrolysate contained 97.8% peptides, in which peptides with a molecular weight lower than 1000 Da and 500 Da accounted for 55.1% and 39.5%, respectively, indicating that the hydrolysate was rich in oligopeptides. These results indicate that Aa2_1884 likely has a promising potential application in the preparation of collagen oligopeptide-rich hydrolysate from bovine bone collagen, which may provide a feasible way for the high-value utilization of bovine bone collagen.

Magnesium sulfate reduces vascular endothelial cell apoptosis in rats with preeclampsia via the miR-218-5p/HMGB1 pathway.

OBJECTIVE: This study aims to investigate the mechanism by which magnesium sulfate regulates the miR-218-5p/HMGB-pathway-mediated apoptosis of vascular endothelial cells (VECs) in rats with preeclampsia (PE). METHODS: Twenty pregnant rats were randomly divided into four groups: normal, PE, MgSO4, and high-mobility group protein B1 (HMGB1)-agomir groups. On the 14th day of each rat's pregnancy, endotoxin was used to establish a PE model in the PE, MgSO4, and HMGB1-agomir groups. Then, the MgSO4 and HMGB1-agomir groups were treated with magnesium sulfate. Finally, HMGB1 overexpression was performed only in the HMGB1-agomir group. The rats' urinary protein content and systolic blood pressure at 24 h were detected on the 11th, 13th, 15th, 17th, and 19th day of pregnancy. RESULTS: Compared with the PE group, 24-h urinary protein content, blood pressure, VEC apoptosis rate, apoptosis marker levels, and HMGB1 expression decreased while miR-218-5p levels increased in the MgSO4 group. The dual-luciferase assay revealed that HMGB1 can be targeted and regulated by miR-218-5p. Compared with the MgSO4 group, 24-h urinary protein content, blood pressure, VEC apoptosis rate, apoptosis marker levels, and HMGB1 expression increased while miR-218-5p levels decreased in the HMGB1-agomir group. CONCLUSION: MgSO4 reduces VEC apoptosis in PE rats via the miR-218-5p/HMGB1 pathway and thus plays a role in treating PE.

Marinifaba aquimaris gen. nov., sp. nov., a novel chitin-degrading gammaproteobacterium in the family Alteromonadaceae isolated from seawater of the Mariana Trench.

A novel Gram-negative, rod-shaped, aerobic, oxidase-positive and catalase-negative bacterium, designated strain SM1970T, was isolated from a seawater sample collected from the Mariana Trench. Strain SM1970T grew at 15-37 oC and with 1-5% (w/v) NaCl. It hydrolyzed colloidal chitin, agar and casein but did not reduce nitrate to nitrite. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain SM1970T formed a distinct lineage close to the genus Catenovulum within the family Alteromonadaceae, sharing the highest sequence similarity (93.6%) with type strain of Catenovulum maritimum but < 93.0% sequence similarity with those of other known species in the class Gammaproteobacteria. The major fatty acids of strain SM1970T were summed feature 3 (C16: 1 ω7c and/or C16: 1 ω6c), C16: 0 and summed feature 8 (C18: 1 ω7c and/or C18: 1 ω6c). The major polar lipids of the strain included phosphatidylethanolamine and phosphatidylglycerol and its main respiratory quinone was ubiquinone 8. The draft genome of strain SM1970T consisted of 77 scaffolds and was 4,172,146 bp in length, containing a complete set of genes for chitin degradation. The average amino acid identity (AAI) values between SM1970T and type strains of known Catenovulum species were 56.6-57.1% while the percentage of conserved proteins (POCP) values between them were 28.5-31.5%. The genomic DNA G + C content of strain SM1970T was 40.1 mol%. On the basis of the polyphasic analysis, strain SM1970T is considered to represent a novel species in a novel genus of the family Alteromonadaceae, for which the name Marinifaba aquimaris is proposed with the type strain being SM1970T (= MCCC 1K04323T = KCTC 72844T).