The widespread use of antimicrobial agent triclosan (TCS) poses significant health risks to both aquatic organisms and humans. The research on its neurotoxicity and underlying mechanisms is, however, limited. Here we first conducted a 32-day exposure experiment with five TCS concentrations (10, 30, 60, 90 and 120 µg/L) to investigate its impact on overall gene expression in Rana omeimontis larvae. Transcriptomics analysis unveiled a strong dose-dependent pattern of gene expression alterations, with a distinct transcriptomic shift observed in the T030 (30 µg/L) group. In addition, neurodegenerative disease pathway and oxidative stress response GO (gene ontology) terms were found to be highly enriched across the regulated genes in all TCS-exposed groups, suggesting potential TCS-induced neurotoxicity. To further explore this, we performed a 40-day experiment with a low (30 µg/L) or high (90 µg/L) TCS concentration. Morphological assessments revealed that TCS-exposed larvae exhibited developmental and growth inhibition. Using RT-qPCR and immunohistochemical analysis, we confirmed that TCS exposure induced neurotoxicity and triggered neurodegenerative diseases as suggested by Tau protein aggregation in the midbrain. Consistent with these findings, TCS-exposed larvae displayed abnormal behaviors. Our study thus for the first time presents a comprehensive assessment of the adverse effects of TCS exposure on amphibian larvae, encompassing morphological, biochemical, and physiological aspects. Notably, we identified RNF112 and Tau as potential molecular targets that may mediate TCS-induced neurotoxicity. These findings advance the knowledge on how organisms respond to environmental changes and highlight the importance of further investigation into the potential neurotoxicity of TCS within aquatic ecosystems and its implications for human health.

Size evolution among gigantic genomes involves gain and loss of many gigabases of transposable elements (TEs), sequences that parasitize host genomes. Vertebrates suppress TEs using piRNA and KRAB-ZFP pathways. TEs and hosts coevolve in an arms race, where suppression strength reflects TE fitness costs. In enormous genomes, additional TE costs become miniscule. How, then, do TEs and host suppression invoke further addition of massive DNA amounts? We analyze TE proliferation histories, deletion rates, and community diversities in six salamander genomes (21.3 - 49.9 Gb), alongside gonadal expression of TEs and suppression pathways. We show that TE activity is higher in testes than ovaries, attributable to lower KRAB-ZFP suppression. Unexpectedly, genome size and expansion are uncorrelated with TE deletion rate, proliferation history, expression, and host suppression. Also, TE community diversity increases with genome size, contrasting theoretical predictions. We infer that TE-host antagonism in gigantic genomes produces stochastic TE accumulation, reflecting noisy intermolecular interactions in huge genomes and cells.

Microorganisms with chitin-degrading capabilities play a crucial role in the biological control of crop pests and diseases as well as in the treatment of organic waste. In this study, a chitin-degrading bacterium, designated L2-2, was isolated from the intestine of Odorrana margaretae collected in Mount Emei, Sichuan, China. Based on physiological and biochemical characteristics, 16S rRNA gene sequencing, and phylogenetic analysis of 31 conserved housekeeping genes in the whole genome, strain L2-2 was identified as a member of the genus Roseateles, named Roseateles sp. L2-2. This strain is able to grow on agar medium with colloidal chitin as the sole carbon source and form clear hydrolysis zones. After optimizing fermentation conditions (including concentrations of nitrogen and carbon sources, culture time, and pH), the enzyme activity was increased to 3.46 U/mL, which was 24 times higher than the initial enzyme activity. Functional genome annotation showed that the strain contains genes encoding endochitinases of the GH18, GH23, and GH46 families, as well as genes encoding β-glucosidases of the GH1, GH2, GH3, and GH109 families, indicating its genetic basis for chitin-degrading potential. This study expands the diversity of known chitin-degrading bacteria and provides a promising microbial resource for the bioremediation of chitinous waste and sustainable pest control in agriculture.

Amphibians serve as reliable indicators of ecosystem health and are the most threatened group of vertebrates. Studies on their spatial distribution pattern and threats are crucial to formulate conservation strategies. Gongga Mountains, with a peak at 7509 m a.s.l. and running latitudinally, are in the center of the Hengduan Mountains Range and at the eastern steep edge of the Qinghai–Xizang Plateau, providing heterogeneous habitats and varied niches for amphibians. In this study, we combined 83 days of field work with information from 3894 museum specimens that were collected over the past 80 years, and identified twenty amphibian species belonging to seven families and twelve genera by morphology. Of these species, seven were listed in the threatened categories of the Red List of China’s Biodiversity and thirteen were endemic to China. Ten species were found on the plateau side (western slope) and eleven species were found on the other side close to the Sichuan Basin (eastern slope). Only one species was found on both sides, indicating different community structures horizontally. The species richness was unimodal vertically and peaking at mid elevation on both sides, with the maximum number (ten vs. nine) of species occurring at 3300–3700 vs. 1700–1900 m a.s.l. and in different types of vegetation. The elevation span and body length of species distributed on both slopes did not show significant differences. These findings help to understand the horizontal and vertical distribution pattern of amphibian diversity, laying a foundation for future biogeographical and conservation research in this area.

Size evolution among gigantic genomes involves gain and loss of many gigabases of transposable elements (TEs), sequences that parasitize host genomes. Animals suppress TEs using piRNA and KRAB-ZFP pathways. TEs and hosts coevolve in an arms race, where suppression strength reflects TE fitness costs. In enormous genomes, additional TE costs become miniscule. How, then, do TEs and host suppression invoke further addition of massive DNA amounts? We analyzed TE proliferation histories, deletion rates, and community diversities in six salamander genomes (21.3 - 49.9 Gb), alongside gonadal expression of TEs and suppression pathways. TE activity is higher in testes than ovaries, attributable to lower KRAB-ZFP suppression. Unexpectedly, genome size/expansion is uncorrelated with TE deletion rate, proliferation history, expression, and host suppression. Also, TE community diversity increases with genome size, contrasting theoretical predictions. TE/host antagonism in gigantic genomes likely produces stochastic TE accumulation, determined by noisy intermolecular interactions in huge genomes/cells. ### Competing Interest Statement The authors have declared no competing interest.

Transposable elements (TEs) and the silencing machinery of their hosts are engaged in a germline arms-race dynamic that shapes TE accumulation and, therefore, genome size. In animal species with extremely large genomes (>10 Gb), TE accumulation has been pushed to the extreme, prompting the question of whether TE silencing also deviates from typical conditions. To address this question, we characterize TE silencing via two pathways—the piRNA pathway and KRAB-ZFP transcriptional repression—in the male and female gonads of Ranodon sibiricus, a salamander species with a ∼21 Gb genome. We quantify 1) genomic TE diversity, 2) TE expression, and 3) small RNA expression and find a significant relationship between the expression of piRNAs and TEs they target for silencing in both ovaries and testes. We also quantified TE silencing pathway gene expression in R. sibiricus and 14 other vertebrates with genome sizes ranging from 1 to 130 Gb and find no association between pathway expression and genome size. Taken together, our results reveal that the gigantic R. sibiricus genome includes at least 19 putatively active TE superfamilies, all of which are targeted by the piRNA pathway in proportion to their expression levels, suggesting comprehensive piRNA-mediated silencing. Testes have higher TE expression than ovaries, suggesting that they may contribute more to the species’ high genomic TE load. We posit that apparently conflicting interpretations of TE silencing and genomic gigantism in the literature, as well as the absence of a correlation between TE silencing pathway gene expression and genome size, can be reconciled by considering whether the TE community or the host is currently “on the attack” in the arms race dynamic.

γ-aminobutyric acid (GABA) has various physiological functions and is widely used in medicine, food, and other fields. Glutamate decarboxylase (GAD) is a key enzyme that catalyzes the decarboxylation of L-glutamate to synthesize GABA. However, the industrial application of microorganism-derived GAD is limited by its rapid loss of enzymatic activity with pH approaching neutrality. In this study, a novel glutamate decarboxylase, GADMSM, from Mycobacterium smegmatis was overexpressed and purified. On the basis of homologous modeling and substrate molecular docking, several GADMSM mutants were constructed, and their enzymatic properties were analyzed. The results showed that the optimal pH of wild-type GADMSM is 5.4; at pH 6.2, 22.8% enzymatic activity was retained. The T211I replacement in GAD and C-terminal deletion mutant GADMSMΔC showed relatively high catalytic activity in a pH range of 5.0–7.0. The Vmax and Km values of GADMSMΔC were 14.69 and 5.70, respectively, at pH 5.5, and 9.87 and 6.17, respectively, at pH 7.0. Compared with the wild-type GAD, GADMSMΔC maintained higher affinity and enzymatic activity of the substrate, maintaining 78.5% of the highest enzymatic activity even at pH 7.0, which is the highest reported activity retention for GAD under neutral pH condition. Therefore, GADMSMΔC can be used for the transformation of high-yielding strains and industrial production of GABA.

为了探究水域三氯生(TCS)污染对峨眉林蛙Rana omeimontis蝌蚪生长发育的影响,本研究以峨眉林蛙蝌蚪(G22期)为试验对象,进行了96 h急性毒性实验和21 d慢性毒性实验.急性毒性实验中每隔24 h记录蝌蚪的死亡数;慢性毒性实验分别于饲养0d、7d、14d、21d测定蝌蚪的体质量、全长、头体长、尾长、吻长和眼间距.结果表明:96 h-LC50为266μg·L?1、96 h-SC为89μg·L?1,可知TCS对峨眉林蛙蝌蚪为高毒化合物,强烈影响其生长发育.慢性毒性实验暴露21 d,30μg·L?1、60μg·L?1、90μg·L?1、120μg·L?1浓度的TCS极显著抑制蝌蚪的体质量增长,60μg·L?1、90μg·L?1、120μg·L?1浓度的TCS极显著抑制蝌蚪的吻长增长.建议减少TCS污水排放,控制水体中TCS浓度.

Lignocellulosic biomass is an important raw material which has been extensively studied for biotechnological applications, but research on its use for the production of gamma-polyglutamic acid (gamma-PGA) is rarely reported. The present study aimed to improve the release of xylose and glucose from corncob for gamma-PGA production using the strain Bacillus subtilis SCP010-1, which could metabolize xylose. The effectiveness of the three chemical reagents NaOH, NH3 and H2O2 pretreatments was investigated by the response surface methodology (RSM). The results showed that maximum glucose and xylose yields of 11.8 +/- 0.3 and 17.36 +/- 0.6 g/L, respectively, as determined by phloroglucinol-acid and enzymatic methods, were obtained when using 0.986% of NaOH for 2.07 h. Then, the pretreatment solution was subject to further optimize conditions of enzymatic hydrolysis, and the content of glucose and xylose in the corncob hydrolysate reached respectively 15.3 +/- 0.3 and 22.34 +/- 0.17 g/L under synergism of hemicellulase and cellulase. Finally, the fermentation conditions for gamma-PGA production by B. subtilis SCP010-1 were also optimized, and after adding supplemental nutrients to the corncob hydrolysate, a maximum gamma-PGA production of 30.035 +/- 0.49 g/L was achieved by fed batch fermentation with feeding corncob hydrolysate. Considering the cost of the materials used in this study, nearly 85% of reduction in cost could be achieved, hence indicating that this production plan offers good prospects for industrial production of gamma-PGA. More importantly, this process allows the use of environmental-friendly biological resources. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

A haloalkaliphilic strain (IM 1326 T ) was isolated from brine sampled at a soda lake in the Inner Mongolia Autonomous Region, China. Cells of the strain were rod-shaped and motile. Strain IM 1326 T was able to grow at 4–42 °C (optimum, 37 °C) with 0–13.0 % (w/v) NaCl concentrations (optimum at 4.0–6.0 %) and at pH 7.5–11.0 (optimum at 9.0–10.0). The 16S rRNA gene phylogenetic analysis revealed that the isolate belongs to the genus Aliidiomarina and is closely related to the type strains of Aliidiomarina sanyensis (95.8 % sequence similarity), Aliidiomarina shirensis (95.7 %), Aliidiomarina iranensis (95.4 %) and Aliidiomarina haloalkalitolerans (95.3 %). The whole genome of strain IM 1326 T was sequenced, and the genomic DNA G+C content was 49.7 mol%. Average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values between the isolate and the related Aliidiomarina species were 68.1–84.9 %, 76–78 % and 18.4–20.4 %, respectively. The respiratory quinone was ubiquinone-8. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and one unidentified aminophospholipid. The predominant cellular fatty acids were summed feature 9 (10-methyl-C 16 : 0 /iso-C 17 : 1 ω 9 c , 22.2 %), iso-C 15 : 0 (16.1 %) and iso-C 17 : 0 (13.1 %). Based on the results of phylogenetic analysis, genome relatedness, and the physiological and chemotaxonomic properties of the isolate, strain IM 1326 T is considered to represent a novel species of the genus Aliidiomarina , for which the name Aliidiomarina halalkaliphila sp. nov. is proposed (type strain IM 1326 T =CGMCC 1.17056 T =JCM 34227 T ).

为了有效地筛选获得γ-聚谷氨酸(γ-PGA)高产菌株和便于发酵条件的优化,建立了基于微孔板微缩发酵以及利用酶标仪快速检测γ-PGA的方法.利用单因素实验优化检测条件,优化后的检测波长、温度、十六烷基三甲基溴化铵(CTAB)浓度、反应时间分别为430 nm、25℃、15g/L、2 min,在此条件下构建的标准曲线R2达到了0.9995,与酸水解法的实验结果具有高度的一致性,用此法对不除菌与除菌的发酵液分别进行测定,发现二者无显著性差异;以不同氮源为变量,利用24、48孔深孔板发酵,皮尔逊分析显示实验菌株Bacillus subtilis SCP01O-1生长情况与γ-PGA产量均与摇瓶发酵具有良好的相关性.说明利用微孔板进行微缩发酵、随后利用酶标仪对发酵液直接进行检测,可以克服传统检测方法与γ-PGA摇瓶发酵耗时长、试剂消耗量大等不足,在γ-PGA高产菌株筛选和发酵条件优化等方面具有应用价值.

The mitochondrial genome of the spectacled parrotbill Sinosuthora conspicillata is sequenced by the Sanger method. The genome is 16,982 bp in length, comprising of 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, 1 control region (D-loop), and 1 pseudo-control region. The PCGs of COX1 and ND3 use GTG and ATA as their starting codon, respectively, while all other PCGs start with ATG codons. Four PCGs (COX3, ND4, ND5, and ND6) are terminated with CCT, TAT, AGA, and TAG, respectively, and all other PCGs end with TAA. The 22 tRNAs range from 66 bp (tRNA-Ser) to 75 bp (tRNA-Leu) in length. The two rRNAs are 984 bp (12S) and 1600 bp (16S) in length. Phylogenetic analysis indicated that S. conspicillata is closely related to the congeneric vinous-throated parrotbill S. webbiana. This mitochondrial genome sequence offers a valuable resource for future conservation genetic and phylogenetic studies of birds in the family Sylviidae (Passeriformes).

Aminolevulinic acid (ALA), a type of natural non-protein amino acid, is a key precursor for the biosynthesis of heme, and it has been broadly applied in medicine, agriculture. Several strategies have been applied to enhance ALA synthesis in bacteria. In the present study, we employed synthetic antisense RNAs (asRNAs) of hemB (encodes ALA dehydratase) to weaken metabolic flux of ALA to porphobilinogen (PBG), and investigated their effect on ALA accumulation. For this purpose, we designed and constructed vectors pET28a-hemA-asRNA and pRSFDuet-hemA-asRNA to simultaneously express 5-ALA synthase (ALAS, encoded by hemA) and PTasRNAs (2 inverted repeat DNA sequences sandwiched with the antisense sequence of hemB), selecting the region ranging from − 57 nt upstream to + 139 nt downstream of the start codon of hemB as a target. The qRT-PCR analysis showed that the mRNA levels of hemB were decreased above 50% of the control levels, suggesting that the anti-hemB asRNA was functioning appropriately. ALA accumulation in the hemB weakened strains were 17.6% higher than that obtained using the control strains while accumulating less PBG. These results indicated that asRNAs can be used as a tool for regulating ALA accumulation in E. coli.

黄喉貂(Martes flavigula)也称青鼬,为食肉目大型鼬科动物,头体长45～65 cm,粗大显眼的尾长37～45 cm(李晟2019),为相对严格的昼行性动物(Grassman et al.2005,朱博伟等2019).黄喉貂的食谱很广,包括兽类、鸟类、爬行类、两栖类、无脊椎动物、植物的果实、蜂蜜等,在部分地区被称为"蜜狗".仅Zhou等(2011)在黄喉貂粪便中发现蛇的碎屑.

The metabolism of host cholesterol by Mycobacterium tuberculosis is an important factor for both its virulence and pathogenesis. However, the rationale for this cholesterol metabolism has not been fully understood yet. In the present study, we characterized several previously undescribed acyl-CoA synthetases that are involved in the steroid side-chain degradation in Mycobacterium smegmatis, and an analogue of intermediate from steroid degradation, 5'-O-(lithocholoyl sulfamoyl) adenosine (LCA-AMS), was successfully designed and synthesized to be used as a specific anti-mycobacterial agent. The acyl-CoA synthetases exhibited strong preferences for the length of side chain. FadD19 homologs, including FadD19 (MSMEG_5914), FadD19-2 (MSMEG_2241), and FadD19-4 (MSMEG_3687), are unanimously favorable cholesterol with a C8 alkanoate side chain. FadD17 (MSMEG_5908) and FadD1 (MSMEG_4952) showed high preferences for steroids, containing a C5 alkanoate side chain. FadD8 (MSMEG_1098) exhibited specific activity toward cholestenoate with a C8 alkanoate side chain. An acylsulfamoyl analogue of lithocholate, 5'-O-(lithocholoyl sulfamoyl) adenosine (LCA-AMS), was designed and synthesized. As expected, the intermediate analogue not only specifically inhibited those steroid-activated acyl-CoA synthetases, but also selectively inhibited the growth of mycobacterial species, including M. tuberculosis, M. smegmatis, and Mycobacterium neoaurum. Overall, our research advanced our understanding of mycobacterial steroid degradation and provided new insights to develop novel mechanism-based anti-mycobacterial agents.

The diskless-fingered odorous frog Odorrana grahami is widely distributed in the high-altitude mountains in the southwestern China and northern Indochina regions. In this study, a comparative analysis of the mitochondrial COI gene sequences was performed to examine the population genetic diversity of 76 individuals from 10 localities across the distributional range of the species. Haplotype diversity and nucleotide diversity were 0.605 and 0.00199, respectively, in the total population. An AMOVA indicated that 47.3% of the total variation originated from variation within individual populations and 52.7% came from variation between the 10 geographic populations. Tests of neutral evolution indicated that a recent expansion occurred in total population. The findings provide useful information for the conservation of this species.

Cytochrome P450 reductase (CPR) is an integral component of the P450 oxidoreductase system (P450s). It serves as the electron donor for most cytochromes in P450s, which are involved in the metabolism of foreign compounds and the synthesis of endocrine hormones and have tremendous biotechnological potential for the synthesis of pharmaceuticals and fine chemicals. However, commercially available CPR is very expensive, and heterologous expression in Escherichia coli is a more affordable way to obtain enough CPR. In the present study, a full-length cDNA encoding a CPR was isolated from the liver of the Chinese white rabbit using reverse transcription-polymerase chain reaction (RT-PCR). The cDNA contains a 2,040-bp open reading frame, which is predicted to encode an enzyme of 679 amino acids. The deduced peptide shares 99.5% amino acid similarity with CPR of Oryctolagus cuniculus, showing that the Chinese white rabbit is a close genetic relative of the European rabbit. The cloned CPR has the typical hallmarks, including an N-terminal membrane anchor and flavin adenine dinucleotide (FAD)-, flavin mononucleotide (FMN)- and nicotinamide adenine dinucleotide phosphate (NADPH)-binding domains. An N-terminally truncated protein was heterologously expressed in E. coli BL21 (DE3) cells and purified, and the specific activity of the recombinant enzyme was determined. The enzyme activity analysis indicated that electrons were passed from NADPH to Cyt C at a rate of 2.3174 μmol/(min/mg protein). The present study provides an efficient procedure for preparing large amounts of recombinant CPR, which would facilitate the synthesis of pharmaceuticals and fine chemicals with P450s.

2014年8月在西藏自治区阿里地区札达县马阳河谷采集到2号蛇类标本,经查阅文献、咨询,鉴定为中国游蛇科(Serpentes,Colubridae,Colubrinae):新记录属(Platyceps Blyth,1860)和一新记录种Platyceps rhodorachis(Jan,1863),检视标本存于湖南师范大学生命科学学院.

The skin innate immunities of diskless-fingered odorous frogs (Odorrana grahami) from three populations were investigated. The antimicrobial capacities of skin secretions against the 60 representative environmental bacterial strains were evaluated using the values of the minimum inhibitory concentration (MIC) equivalents, which were defined as the volumes of antimicrobial solution just inhibiting the tested bacteria per 1 cm(2) of surface area, from 0.06 to 9.10 mL/cm(2). Our results revealed significantly different skin antimicrobial capacities among the three populations: Mianning < Huili < Kunming. Within the frog population, the skin antimicrobial capacities are highly variable depending on the season: in Mianning frogs, summer < autumn and spring; in Huili frogs, spring < autumn < summer; in Kunming frogs, autumn < spring < summer. The animal density and body mass significantly impacted the skin antimicrobial capacity, while the sex ratio and soil or water bacterial counts did not.

The genus Rattus is one of the main pest genus of rodent. Most species of the genus carry all kinds of pathogenic bacteria to human being. They are traditionally considered to be a least understood group. The complete mitochondrial genome of the White-Footed Indochinese Rat, Rattus nitidus was determined in this study. The characterization of mitochondrial genomes of Rattus genus was also analyzed based on comprehensive comparison. The result of evolutionary patterns of protein-coding genes (PCGs) suggested purifying selection was the predominant evolutionary forces in the mitochondrial genomes of Rattus genus. The NADH dehydrogenase 4 gene (ND4) showed a highly elevated Ka/Ks ratio compared to the other protein-coding genes, which indicated ND4 was most likely under relaxed selection pressure. Phylogenetic analysis provided a well-supported outline of Rattus genus, and revealed two groups in the genus. R. nitidus had a sister relationship with R. norvegicus.