Microbial metabolism and necromass mediated fertilization effect on soil organic carbon after long-term community incubation in different climates

Understanding the effects of changing climate and long-term human activities on soil organic carbon (SOC) and the mediating roles of microorganisms is critical to maintain soil C stability in agricultural ecosystem. Here, we took samples from a long-term soil transplantation experiment, in which large transects of Mollisol soil in a cold temperate region were translocated to warm temperate and mid-subtropical regions to simulate different climate conditions, with a fertilization treatment on top. This study aimed to understand fertilization effect on SOC and the role of soil microorganisms featured after long-term community incubation in warm climates. After 12 years of soil transplantation, fertilization led to less reduction of SOC, in which aromatic C increased and the consumption of O-alkyl C and carbonyl C decreased. Soil live microbes were analyzed using propidium monoazide to remove DNAs from dead cells, and their network modulization explained 60.4% of variations in soil labile C. Single-cell Raman spectroscopy combined with D₂O isotope labeling indicated a higher metabolic activity of live microbes to use easily degradable C after soil transplantation. Compared with non-fertilization, there was a significant decrease in soil α- and β-glucosidase and delay on microbial growth with fertilization in warmer climate. Moreover, fertilization significantly increased microbial necromass as indicated by amino sugar content, and its contribution to soil resistant C reached 22.3%. This study evidentially highlights the substantial contribution of soil microbial metabolism and necromass to refractory C of SOC with addition of nutrients in the long-term.Subject terms: Microbial ecology, Biodiversity     

The myocardial response to adrenomedullin involves increased cAMP generation as well as augmented Akt phosphorylation

In this work we aimed to observe (1) the changes in adrenomedullin (AM) and its receptor system - calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMPs) - in myocardial ischemic injury and (2) the response of injuried myocardia to AM and the phosphorylation of Akt to illustrate the protective mechanism of AM in ischemic myocardia. Male SD rats were subcutaneously injected with isoproterenol (ISO) to induce myocardial ischemia. The mRNA levels of AM, CRLR, RAMP1, RAMP2 and RAMP3 were determined by RT-PCR. Protein levels of Akt, phosphor-Akt, CRLR, RAMP1, RAMP2 and RAMP3 were assayed by Western blot. Results showed that, compared with that of the controls, ISO-treated rats showed lower cardiac function and myocardial injury. The mRNA relative amount of AM, CRLR, RAMP1, RAMP2 and RAMP3 in the myocardia of ISO-treated rats was increased. The elevated mRNA levels of CRLR, RAMP1, RAMP2 and RAMP3 were positively correlated with AM content in injured myocardia. The protein levels of CRLR, RAMP1, RAMP2 and RAMP3 in injured myocardia were increased compared with that of control myocardia. AM-stimulated cAMP generation in myocardia was elevated in the ISO group, and was antagonized by AM(22-52) and CGRP(8-37). Western blot analyses revealed that AM significantly enhanced Akt phosphorylation in injured myocardia, which was blocked by pretreatment with AM(22-52) or CGRP(8-37). Ischemia-injured myocardia hyper-expressed AM and its receptors - CRLR, RAMP1, RAMP2 and RAMP3 - and the response of ischemic myocardia to AM was potentiated, and the level of Akt phosphorylation was also increased, which suggests that changes in cardiac AM/AM receptor might play an important role in the pathogenesis of myocardial ischemic injury.     

冠心病患者血清CRP的变化及其临床意义

目的:探讨冠心病(CAD)患者血清C-反应蛋白(CRP)的变化及其临床意义.方法:运用全自动生化分析仪检测97例CAD患者和28例对照组人群的血清CRP,将CAD患者进一步分为稳定性心绞痛组(SAP)、不稳定心绞痛(UAP)、心肌梗死组(AMI)三组.另外,将97例CAD惠者分为1支病变组、2支病变组和3支病变组.所有研究对象均行选择性冠状动脉造影检查.结果:(1)与对照组比较,CAD患者血清CRP显著升高(P<0.05);(2)与对照组比较,SAP组、UAP组和AMI组患者血清CRP均显著升高(P<0.05);与SAP组比较,UAP组和AMI组患者血清CRP亦显著升高(P<0.05);(3)与对照组比较,1支病变组、2支病变组和3支病变组患者血清CRP均显著升高(P<0.05);与1支病变组比较,2支病变组和3支病变组患者血清CRP亦显著升高(P<0.05);与2支病变组比较,3支病变组患者血清CRP亦显著升高(P<0.05).结论:(1)CRP可能与CAD有关;(2)CRP异常升高可能反映冠状动脉斑块的不稳定和CAD的严重程度.     

Influence of the APOA5 locus on plasma triglyceride, lipoprotein subclasses, and CVD risk in the Framingham Heart Study

Several polymorphisms in the APOA5 gene have been associated with increased plasma triglyceride (TG) concentrations. However, associations between APOA5 and lipoprotein subclasses, remnant-like particles (RLPs), and cardiovascular disease (CVD) risk have been less explored. We investigated associations of five APOA5 single-nucleotide polymorphisms (SNPs; -1131T>C, -3A>G, 56C>G IVS3+ 476G>A, and 1259T>C) with lipoprotein subfractions and CVD risk in 1,129 men and 1,262 women participating in the Framingham Heart Study. Except for the 56C>G SNP, the other SNPs were in significant linkage disequilibria, resulting in three haplotypes (11111, 22122, and 11211) representing 98% of the population. SNP analyses revealed that the -1131T>C and 56C>G SNPs were significantly associated with higher plasma TG concentrations in both men and women. For RLP and lipoprotein subclasses, we observed gender-specific association for the -1131T>C and 56C>G SNPs. Female carriers of the -1131C allele had higher RLP concentrations, whereas in males, significant associations for RLPs were observed for the 56G allele. Moreover, haplotype analyses confirmed these findings and revealed that the 22122 and 11211 haplotypes exhibited different associations with HDL cholesterol concentrations. In women, the -1131C allele was associated with a higher hazard ratio for CVD (1.85; 95% confidence interval, 1.03-3.34; P = 0.04), in agreement with the association of this SNP with higher RLPs.     

The thymic stromal cell line MTSC4 induced thymocyte apoptosis in a non-MHC-restricted manner

Mouse thymic stromal cell line 4 (MTSC4) is one of the stromal cell lines established in our laboratory. While losing the characteristics of epithelial cells, they express some surface markers shared with thymic dendritic cells (TDCs). To further study the biological functions of these cells, we compared the capability of MTSC4 with TDCs in the induction of thymocyte apoptosis, using thymic reaggregation culture system. Apoptosis of thymocytes induced by MTSC4 and TDCs was measured by Annexin V and PI staining and analyzed by flow cytometry. We found that MTSC4 selectively augmented the apoptosis of CD4^ 8^ (DP) thymocytes. This effect was Fas/FasL independent and could not be blocked by antibodies to MHC class I and class II molecules. In addition, MTSC4 enhanced the apoptosis of DP thymocytes from different strains of mice, which implies that MTSC4-induced thymocyte apoptosis is not mediated by the TCR recognition of self peptide/MHC molecules. In contrast to MTSC4, thymocyte apoptosis induced by TDCs was MHC-restricted. Thus, MHC-independent fashion of stromal-DP thymocyte interaction may be one of the ways to induce thymocyte apoptosis in thymus. Our study has also shown that the interaction of MTSC4 stromal cells and thymocytes is required for the induction of thymocyte apoptosis.     

Indene bioconversion by a toluene inducible dioxygenase of Rhodococcus sp. I24

Rhodococcus sp. I24 can oxygenate indene via at least three independent enzyme activities: (i) a naphthalene inducible monooxygenase (ii) a naphthalene inducible dioxygenase, and (iii) a toluene inducible dioxygenase (TID). Pulsed field gel analysis revealed that the I24 strain harbors two megaplasmids of 340 and 50 kb. Rhodococcus sp. KY1, a derivative of the I24 strain, lacks the 340 kb element as well as the TID activity. Southern blotting and sequence analysis of an indigogenic, I24-derived cosmid suggested that an operon encoding a TID resides on the 340 kb element. Expression of the tid operon was induced by toluene but not by naphthalene. In contrast, naphthalene did induce expression of the nid operon, encoding the naphthalene dioxygenase in I24. Cell free protein extracts of Escherichia coli cells expressing tidABCD were used in HPLC-based enzyme assays to characterize the indene bioconversion of TID in vitro. In addition to 1-indenol, indene was transformed to cis-indandiol with an enantiomeric excess of 45.2% of cis-(1S,2R)-indandiol over cis-(1R,2S)-indandiol, as revealed by chiral HPLC analysis. The K_m of TID for indene was 380 M. The enzyme also dioxygenated naphthalene to cis-dihydronaphthalenediol with an activity of 78% compared to the formation of cis-indandiol from indene. The K_m of TID for naphthalene was 28 M. TID converted only trace amounts of toluene to 1,2-dihydro-3-methylcatechol after prolonged incubation time. The results indicate the role of the tid operon in the bioconversion of indene to 1-indenol and cis-(1S,2R)-indandiol by Rhodococcus sp. I24.     

补充益生菌对功能性腹泻患者焦虑抑郁状态的影响

目的探讨益生菌对功能性腹泻患者临床症状和心理健康的影响。方法将2019年3月至2019年12月在广东省肇庆市高要区人民医院消化内科门诊收治的伴有焦虑抑郁状态的90例功能性腹泻住院病人随机分为试验组、对照组A、对照组B。三组受试者均口服匹维溴铵,试验组口服双歧杆菌四联活菌,对照组A服用氟西汀,对照组B未给其他药物治疗,疗程均为1个月。治疗前后,比较患者大便次数及性状、汉密尔顿焦虑量表(HAMA)和汉密尔顿抑郁量表(HAMD)评分。结果治疗前三组患者每周排便不同次数的人数比较,差异无统计学意义(P>0.05)。治疗第3周和第4周后,与对照组A相比,对照组B和试验组的排便不同次数的人数差异具有统计学意义(P<0.05)。治疗第4周后,试验组与对照组B的排便不同次数的人数比较,差异具有统计学意义(P<0.05)。治疗前3组患者Bristol粪便性状评分比较差异无统计学意义(P>0.05)。治疗第3和第4周后,与对照组A相比,对照组B和试验组的Bristol粪便性状评分比较,差异有统计学意义(P<0.05)。治疗第4周后,试验组与对照组B的Bristol粪便性状评分比较,差异有统计学意义(P<0.05)。治疗后与对照组A比较,对照组B和试验组HAMA评分和HAMD评分显著低于对照组A,且差异具有统计学意义(P<0.05)。与对照组B比较,试验组HAMA评分和HAMD评分显著低于对照组B(P<0.05)。结论通过补充益生菌可调节功能性腹泻患者腹泻次数,提高功能性腹泻患者生活质量,改善患者焦虑抑郁症状。     

Improving the acidic stability of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> α-acetolactate decarboxylase in <Emphasis Type="Italic">Bacillus subtilis</Emphasis> by changing basic residues to acidic residues

The α-acetolactate decarboxylase (ALDC) can reduce diacetyl fleetly to promote mature beer. A safe strain Bacillus subtilis WB600 for high-yield production of ALDC was constructed with the ALDC gene saald from Staphylococcus aureus L3-15. SDS-PAGE analysis revealed that S. aureus α-acetolactate decarboxylase (SaALDC) was successfully expressed in recombinant B. siutilis strain. The enzyme SaALDC was purified using Ni-affinity chromatography and showed a maximum activity at 45 °C and pH 6.0. The values of K _m and V _max were 17.7 μM and 2.06 mM min^?1, respectively. Due to the unstable property of SaALDC at low pH conditions that needed in brewing process, site-directed mutagenesis was proposed for improving the acidic stability of SaALDC. Homology comparative modeling analysis showed that the mutation (K52D) gave rise to the negative-electrostatic potential on the surface of protein while the numbers of hydrogen bonds between the mutation site (N43D) and the around residues increased. Taken together the effect of mutation N43D-K52D, recombinant SaALDC_N43D-K52D showed dramatically improved acidic stability with prolonged half-life of 3.5 h (compared to the WT of 1.5 h) at pH 4.0. In a 5-L fermenter, the recombinant B. subtilis strain that could over-express SaALDC_N43D-K52D exhibited a high yield of 135.8 U mL^?1 of SaALDC activity, about 320 times higher comparing to 0.42 U mL^?1 of S. aureus L3-15. This work proposed a  strategy for improving the acidic stability of SaALDC in the  B. subtilis host.