Morphological, Microstructural, and In Situ Chemical Characteristics of Siderite Produced by Iron-Reducing Bacteria.

Dissimilatory iron-reducing bacteria (DIRB) oxidize organic matter or hydrogen and reduce ferric iron to form Fe(II)-bearing minerals, such as magnetite and siderite. However, compared with magnetite, which was extensively studied, the mineralization process and mechanisms of siderite remain unclear. Here, with the combination of advanced electron microscopy and synchrotron-based scanning transmission X-ray microscopy (STXM) approaches, we studied in detail the morphological, structural, and chemical features of biogenic siderite via a growth experiment with Shewanella oneidensis MR-4. Results showed that along with the growth of cells, Fe(II) ions were increasingly released into solution and reacted with CO32- to form micrometer-sized siderite minerals with spindle, rod, peanut, dumbbell, and sphere shapes. They are composed of many single-crystal siderite plates that are fanned out from the center of the particles. Additionally, STXM revealed Fh and organic molecules inside siderite. This suggests that the siderite crystals might assemble around a Fh-organic molecule core and then continue to grow radially. This study illustrates the biomineralization and assembly of siderite by a successive multistep growth process induced by DIRB, also provides evidences that the distinctive shapes and the presence of organic molecules inside might be morphological and chemical features for biogenic siderite.

UBE2J1 promotes ALV-A proviral DNA synthesis through the STAT3/IRF1 signaling pathway.

The ubiquitin-binding enzyme E2J1 is located on the endoplasmic reticulum membrane. It plays a role in transport throughout the process of ubiquitination. In mammals, UBE2J1 can promote RNA virus replication. However, the biological function of chicken UBE2J1 is unclear. In this study, chicken UBE2J1 was cloned for the first time, and UBE2J1 overexpression and shRNA knockdown plasmids were constructed. In chicken embryo fibroblasts, overexpression of UBE2J1 promoted the replication of subtype A avian leukosis virus, while knockdown of UBE2J1 inhibited the replication of ALV-A virus. In addition, we divided virus replication into virus adsorption and invasion into DF-1 cells, synthesis of proviral DNA, and release of viral particles. UBE2J1 promoted the replication of ALV-A virus by promoting the synthesis of proviral DNA. This result was caused by UBE2J1 inhibiting the production of interferon by inhibiting the STAT3/IRF1 pathway. We mutated ser at position 184 of UBE2J1 to Gly and found that this site plays a role as the phosphorylation site of UBE2J1. We confirmed that UBE2J1 promotes ALV-A replication in chicken embryo fibroblasts by inhibiting the STAT3/IRF1 pathway. This study provides new ideas and insights into ubiquitin-related proteins and antiviral immunity.

Electrochemically active iron (III)-reducing bacteria in coastal riverine sediments.

Iron (III)-reducing bacteria (IRB) play significant roles in the degradation of naturally occurring organic matter and in the cycling of heavy metals in marine and freshwater sediments. Our previous study has demonstrated the co-occurrence of Geobacteraceae and Methanosarcinamazei as aggregates in the iron (III)-reducing enrichments from a coastal gold mining site on the Jiehe River. The IRB community in the enriched sediments was dominated by members of Comamonadacea, Clostridiaceae, Bacillaceae, Bacteroidaceae, and Geobacteraceae. Furthermore, four representative strains (JhA, JhB, JhC-1, and JhC-2) were isolated and found to belong to the genus of Anaerosinus, Bacillus, and Clostridium with 97.31-98.82% identity of 16S rRNA genes. The iron (III)-reducing ability of all these isolates was identified. Interestingly, JhA showed electrochemical activity with chronoamperometry (CA) and cyclic voltammetry (CV), indicating its ability to oxidize ethanol, liberate, and transfer electrons, thus, expanding our knowledge of a new genus with electrochemical activity. The results revealed the cultivability and electrochemical activity of IRB in coastal riverine sediment and indicated that JhA was an unknown extracellular electron producer with the ability to reduce iron (III). This study expands our knowledge of the electrochemical characterization of the genus Anaerosinus. It is reasonable to expect that these isolates have potential applications in heavy metal bioremediation operations in natural environments.

Co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture.

Methanosaeta harundinacea and Methanosarcina barkeri, known as classic acetoclastic methanogens, are capable of directly accepting electrons from Geobacter metallireducens for the reduction of carbon dioxide to methane, having been revealed as direct interspecies electron transfer (DIET) in the laboratory co-cultures. However, whether their co-occurrences are ubiquitous in the iron (III)-reducing environments and the other species of acetoclastic methanogens such as Methanosarcina mazei are capable of DIET are still unknown. Instead of initiating the co-cultures with pure cultures, two-step cultivation was employed to selectively enrich iron (III)-reducing microorganisms in a coastal gold mining river, Jiehe River, with rich iron content in the sediments. First, iron (III) reducers including Geobacteraceae were successfully enriched by 3-months successive culture on amorphous Fe(III) oxides as electron acceptor and acetate as electron donor. High-throughput Illumina sequencing, terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis based on 16S rRNA genes revealed that the enrichment cultures actively contained the bacteria belong to Geobacteraceae and Bacilli, exclusively dominated by the archaea belong to Methanosarcinaceae. Second, the enrichment cultures including methanogens and Geobacteraceae were transferred with ethanol as alternative electron donor. Remarkably, aggregates were successively formed in the enrichments after three transfers. The results revealed by RNA-based analysis demonstrate that the co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture. Furthermore, the aggregates, as close physical contact, formed in the enrichment culture, indicate that DIET could be a possible option for interspecies electron transfer in the aggregates.

Endoplasmic reticulum export and vesicle formation of the movement protein of Chinese wheat mosaic virus are regulated by two transmembrane domains and depend on the secretory pathway.

The 37K protein of Chinese wheat mosaic virus (CWMV) belongs to the 30K superfamily of plant virus movement proteins. CWMV 37K trans-complemented the cell-to-cell spread of a movement-defective Potato virus X. CWMV 37K fused to enhanced green fluorescent protein localized to plasmodesmata and formed endoplasmic reticulum (ER)-derived vesicular and large aggregate structures. CWMV 37K has two putative N-terminal transmembrane domains (TMDs). Mutations disrupting TMD1 or TMD2 impaired 37K movement function; those mutants were unable to form ER-derived structures but instead accumulated in the ER. Treatment with Brefeldin A or overexpression of the dominant negative mutant of Sar1 retained 37K in the ER, indicating that ER export of 37K is dependent on the secretory pathway. Moreover, CWMV 37K interacted with pectin methylesterases and mutations in TMD1 or TMD2 impaired this interaction in planta. The results suggest that the two TMDs regulate the movement function and intracellular transport of 37K.

[Effect of baicalin on expression of heme oxygenase-1 in lung injury of rats associated with paraquat poisoning].

OBJECTIVE: To investigate the effect of baicalin (Bai) on lung injury, the level of TNF-alpha in cultured liquid of pulmonary interstitial macrophage and the expression of heme oxygenase-1 (HO-1) in lung injury associated with paraquat poisoning. METHODS: Rats were randomizedly divided into four groups: control group, PQ group, Bai group (Bai, 300 mg.kg(-1).d(-1)) and simple Bai group (Bai, 300 mg. kg(-1).d(-1)) (n = 10 in each group). The 2% PQ was injected (25 mg/kg) in PQ group. Bai was injected in the rats (300 mg.kg(-1).d(-1) x 3 d) through caudal vein after paraquat poisoning in Bai group. In simple Bai group, Bai was injected in the healthy rats (300 mg.kg(-1).d(-1) x 3 d). The samples were obtained three days after intraperitoneal administration of 2% paraquat (25 mg/kg). The injury of lung was estimated with HE dyeing and electron microscope. Pulmonary interstitial macrophage (PIM) were obtained, and then cultured for 24 hours. The content of TNF-alpha was evaluated. The expression of HO-1 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). The expression of HO-1 protein was evaluated by Western blot analysis. RESULTS: The lung tissue was normal in control group and simple Bai group. The degree of lung injury in PQ group was higher than that in control group by HE dyeing and electron microscope observation. The level of TNF-alpha expression in cultured PIM in Bai group [(484.2 +/- 39.5) microg/L] was lower than that in PQ group [(790.2 +/- 35.0) microg/L], but higher than that in the control group [(121.6 +/- 19.2) microg/L] (P < 0.05). The expression of HO-1 mRNA and protein [(59.8 +/- 5.40) and (122.0 +/- 31.98)] in Bai group were higher than those in PQ group [(45.9 +/- 5.82) and (77.92 +/- 10.23)] (P < 0.05). CONCLUSION: The lung injury associated with paraquat poisoning was alleviated by baicalin, which was possibly related to the decrease of level of TNF-alpha in cultured PIM and the increase of the expression of HO-1 mRNA and protein.

Cardiac risk stratification in patients with congestive heart failure: a catecholamines-beta-adrenoceptor-cAMP pathway.

OBJECTIVE: To investigate the stratification risk of catecholamines-beta-adrenoceptor (beta-AR)-cAMP pathway for cardiogenic death events in patients with congestive heart failure (CHF). METHODS: A total of 83 identified CHF patients with a baseline and follow-up plasma levels of norepinephrine (NE) and epinephrine (E), lymphocytes beta-AR density (Bmax), and intralymphocyte cAMP content in peripheral blood were followed up. Major cardiogenic death events were registered. RESULTS: The period between the initial entry and the last follow-up measurement were 51 +/- 16 months, the total duration of clinical follow-up after the last measurement were 14 +/- 8 months. During follow-up, 39 patients died of cardiogenic (sudden death 17 patients, worsening heart failure 22 patients). Persistence of high NE, E, and cAMP from baseline to follow-up were confirmed as risk predicting factors of cardiovascular events. Persistence NE above 4.0 nmol/L, E above 3.5 nmol/L, and the intralymphocyte cAMP content above 3.5 pmd x mg(-1) x pro(-1) from baseline to follow-up were significant adverse prognostic predictors. The major cardiogenic death events rates per 100 patients-years were 1.33 and 4.82 in patients with NE below and above 4.0 nmol/L (HR: 2.91; 95% CI: 1.08-7.33; P = 0.015); were 1.42 and 4.36 in the patients with E levels below and above 3.5 nmol/L (HR: 2.64; 95% CI: 1.02-6.41; P = 0.019); were 1.81 and 4.67 in the patients with the intralymphocyte cAMP content below and above 3.5 pmd x mg(-1) x pro(-1) (HR: 2.79; 95% CI: 1.04-6.83; P = 0.017), but difference was not significant between the beta-AR density below and above median. CONCLUSIONS: Persistent increase in circulating catecholamines and intralymphocyte cAMP content may increase the long-term mortality in CHF patients.

Effects of catecholamine-beta-adrenoceptor-cAMP system on severe patients with heart failure.

OBJECTIVE: To investigate the association between catecholamine-beta-adrenoceptor (beta-AR)-adenosine 3', 5'-monophosphate (cAMP) system and long-term prognosis in patients with chronic heart failure (CHF). METHODS: The study population comprised 73 patients with CHF (EF: 23% +/- 10%) with a mean follow-up of 3.8 +/- 1.9 years. Plasma levels of norepinephrine (NE) were measured using high performance lipid chromatography, beta-adrenergic receptor density (Bmax) and the content of cAMP in peripheral lymphocytes were calculated using 3H-dihydroalpneolo as ligand and competitive immunoassay, respectively. Deaths due to cardiovascular events within the follow-up period were registered. RESULTS: The total mortality was 64.7%, 57.4% of which was for cardiogenic (worsening heart failure: 32.4%; sudden death: 25.0%). In the cardiogenic death group, plasma levels of NE and epinephrine (E) (3.74 nmol/L +/- 0.09 nmol/L and 3.17 nmol/L +/- 1.0 nmol/L) and the contents of peripheral lymphocyte cAMP (3.64 pmol/mg protein +/- 1.4 pmol/mg protein) were significantly increased as compared with the survival group (2.68 nmol/L +/- 0.07 nmol/L, 2.41 nmol/L +/- 0.24 nmol/L and 2.73 pmol/mg protein +/- 0.9 pmol/mg protein, respectively, all P < 0.01). In the sudden death group, plasma levels of NE and E (5.01 nmol/L +/- 0.06 nmol/L and 4.13 nmol/L +/- 0.08 nmol/L) were significantly increased as compared with the worsening heart failure group (2.49 nmol/L +/- 0.07 nmol/L and 2.33 nmol/L +/- 0.8 nmol/L, all P < 0.001) and to the survival group (2.68 nmol/L +/- 0.07 nmol/L and 2.41 nmol/L +/- 0.14 nmol/L, all P < 0.01). The incidences of sudden death were 0%, 75%, and 100% (chi(2) = 16.018, P < 0.01) in patients with plasma NE < 2.5 nmol/L, NE 2.5 nmol/L - 4.5 nmol/L, and NE > 4.5 nmol/L, respectively. In the worsening heart failure group, the content of peripheral lymphocyte cAMP (4.46 pmol/mg protein +/- 0.18 pmol/mg protein) was significantly increased compared with the sudden death group (2.39 pmol/mg protein +/- 0.9 pmol/mg protein, P < 0.001) and to the survival group (2.73 pmol/mg protein +/- 1.1 pmol/mg protein, P < 0.001). The worsening heart failure death occurences were 5.0%, 72.2%, and 100% (chi(2) = 14.26, P < 0.01) in patients with a content of peripheral lymphocyte cAMP < 2.5 nmol/L, cAMP 2.5 nmol/L - 4.5 nmol/L, and cAMP > 4.5 nmol/L, respectively. Bmax in peripheral lymphocyte was not significantly different (P > 0.05) among the sudden death, worsening heart failure, and survival groups in CHF patients. CONCLUSIONS: Plasma levels of catecholamine increase significantly, and Bmax and the contents of cAMP in peripheral lymphocytes decrease significantly in patients with CHF. High plasma catecholamine levels may be associated with sudden death, and high intralymphocyte cAMP content may be associated with worsening heart failure in CHF patients.