Genomic analysis of Alteromonas sp. M12 isolated from the Mariana Trench reveals its role in dimethylsulfoniopropionate cycling.

Dimethylsulfoniopropionate (DMSP) is a ubiquitous organosulfur molecule in marine environments with important roles in stress tolerance, global carbon and sulfur cycling, and chemotaxis. It is the main precursor of the climate active gas dimethyl sulfide (DMS), which is the greatest natural source of bio­sulfur transferred from ocean to atmosphere. Alteromonas sp. M12, a Gram-negative and aerobic bacterium, was isolated from the seawater samples collected from the Mariana Trench at the depth of 2500 m. Here, we report the complete genome sequence of strain M12 and its genomic characteristics to import and utilize DMSP. The genome of strain M12 contains one circular chromosome (5,012,782 bp) with the GC content of 40.88%. Alteromonas sp. M12 can grow with DMSP as a sole carbon source, and produced DMS with DMSP as a precursor. Genomic analysis showed that strain M12 contained a set of genes involved in the downstream steps of DMSP cleavage, but no known genes encoding DMSP transporters or DMSP lyases. The results indicated that this strain contained novel DMSP transport and cleavage genes in its genome which warrants further investigation. The import of DMSP into cells may be a strategy of strain M12 to adapt the hydrostatic pressure environment in the Mariana Trench, as DMSP can be used as a hydrostatic pressure protectant. This study sheds light on the catabolism of DMSP by deep-sea bacteria.

Molecular insights into the catalytic mechanism of a phthalate ester hydrolase.

Phthalate esters (PAEs) are emerging hazardous and toxic chemicals that are extensively used as plasticizers or additives. Diethyl phthalate (DEP) and dimethyl phthalate (DMP), two kinds of PAEs, have been listed as the priority pollutants by many countries. PAE hydrolases are the most effective enzymes in PAE degradation, among which family IV esterases are predominate. However, only a few PAE hydrolases have been characterized, and as far as we know, no crystal structure of any PAE hydrolases of the family IV esterases is available to date. HylD1 is a PAE hydrolase of the family IV esterases, which can degrade DMP and DEP. Here, the recombinant HylD1 was characterized. HylD1 maintained a dimer in solution, and functioned under a relatively wide pH range. The crystal structures of HylD1 and its complex with monoethyl phthalate were solved. Residues involved in substrate binding were identified. The catalytic mechanism of HylD1 mediated by the catalytic triad Ser140-Asp231-His261 was further proposed. The hylD1 gene is widely distributed in different environments, suggesting its important role in PAEs degradation. This study provides a better understanding of PAEs hydrolysis, and lays out favorable bases for the rational design of highly-efficient PAEs degradation enzymes for industrial applications in future.

Alternative dimethylsulfoniopropionate biosynthesis enzymes in diverse and abundant microorganisms.

Dimethylsulfoniopropionate (DMSP) is an abundant marine organosulfur compound with roles in stress protection, chemotaxis, nutrient and sulfur cycling and climate regulation. Here we report the discovery of a bifunctional DMSP biosynthesis enzyme, DsyGD, in the transamination pathway of the rhizobacterium Gynuella sunshinyii and some filamentous cyanobacteria not previously known to produce DMSP. DsyGD produces DMSP through its N-terminal DsyG methylthiohydroxybutyrate S-methyltransferase and C-terminal DsyD dimethylsulfoniohydroxybutyrate decarboxylase domains. Phylogenetically distinct DsyG-like proteins, termed DSYE, with methylthiohydroxybutyrate S-methyltransferase activity were found in diverse and environmentally abundant algae, comprising a mix of low, high and previously unknown DMSP producers. Algae containing DSYE, particularly bloom-forming Pelagophyceae species, were globally more abundant DMSP producers than those with previously described DMSP synthesis genes. This work greatly increases the number and diversity of predicted DMSP-producing organisms and highlights the importance of Pelagophyceae and other DSYE-containing algae in global DMSP production and sulfur cycling.

Short-term effect of radioactive iodine therapy on CXCL-10 production in Graves' disease.

PURPOSE: To observe the short-term dynamic change in serum CXC chemokine ligand-10 (CXCL10) levels in patients with Graves' disease (GD) before and after iodine therapy and to analyze the relationship between CXCL10 levels and clinical disease indices. METHODS: ELISA was used to determine serum levels of CXCL10 in 43 patients with GD shortly before radioiodine therapy and on days six, 14, and 60, post-therapy. RESULTS: Patients with newly diagnosed GD showed significantly higher levels of serum CXCL10 compared with the control group (P < 0.01). The serum CXCL10 level increased slightly on day six after treatment of radioactive iodine (P < 0.01). There was no significant statistical difference in serum CXCL10 levels pre-treatment and on day 14 post-treatment. A significant reduction in serum CXCL10 level was observed on day 60 (P < 0.01). GD patients with exophthalmia showed higher serum CXCL10 level than GD patients without exophthalmia. No correlation was found between levels of CXCL10 and FT3, FT4 or TSH at any time point, but significant positive correlation was shown between thyroid peroxidase antibodies (TPOAb) and CXCL10 (r=0.50, P < 0.01). CONCLUSION: CXCL10 participates in the early inflammatory response after radioactive iodine therapy in patients with Graves' disease and shows a strong association with the autoimmune process.

Allogeneic diabetic mesenchymal stem cells transplantation in streptozotocin-induced diabetic rat.

BACKGROUND: Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stroma cells which can provide a potential therapy for diabetes mellitus. But the mechanism is still controversial. Also, the status of BM-MSCs under hyperglycemia is not known. In the present study, we investigated the status of BM-MSCs in experimental-diabetic rat and demonstrated the rescue of experimental diabetes by diabetic MSCs transplantation. METHODS: BM-MSCs were cultured and the potential of multiple-differentiation was identified through induction into osteoblasts. MSCs of passage 3 were used for the following experiment. The MSCs were labeled with 5-bromo-2?-deoxyuridine (BrdU). Diabetes in rats was induced by STZ injection. The rats were divided into three groups: normal control group (no DM, rats treated with saline through tail vein, n=10); DM control group (DM, no transplantation of MSCs, n=20); experimental group (DM and transplantation of MSCs, n=20). Body weight and blood glucose of the rats were monitored during the experiment after transplantation of MSCs. Paraffin sections of pancreas were obtained from rats of each group. Immuno-histochemistry analysis and double immunofluorescence were used to detect the BM-MSCs in the pancreatic tissue and their differentiating state. RESULTS: MSCs were 89.5% labeled by BrdU and DAPI, which was green/blue double stained under fluorescent microscopy. Transplantation of diabetic MSCs resulted in a reduction of hyperglycemia on day 45 in experimental diabetic rats compared with control rats (17.7 mM +/-3.9 vs 27.8 mM +/- 2.1, P < 0.05), There was also a difference between MSC-treated experimental diabetic rats and control rats in body weight (232.7 g +/-19.7 vs 133.3g +/-13.1, P < 0.05). Histological and morphometric analysis of the pancreas of experimental diabetic rats showed the presence and differentiation of transplanted MSCs into insulin-producing cells which evidenced by double-staining of anti-BrdU and insulin. Also, there were many small islets throughout the sections. Their mean area and diameter analysis revealed that they were smaller than control islets (1835.7 +/- 175.8 microm2 vs 13257.2 +/- 1457.6 microm2; 43.5 +/- 3.7 microm vs 119.9 +/- 5.8 microm, respectively, P < 0.05). CONCLUSION: Allogeneic MSCs transplantation can reduce blood glucose level in recipient rats. A relatively small quantity of transplanted diabetic MSCs survive and transdifferentiate into insulin-producing cells in the pancreas of recipient rats. Upon transplantation these cells initiate endogenous pancreatic regeneration by neogenesis of islet of recipient origin. The present study demonstrates that diabetic MSCs retains its stemness and potential to induce pancreatic regeneration on transplantation.

Mesenchymal stem cell therapy for diabetes through paracrine mechanisms.

Type 1 diabetes is a chronic disorder characterized by the destruction of pancreatic islet beta-cells through autoimmune assault. Insulin replacement is the current main therapeutic approach. In recent years, several studies have showed that mesenchymal stem cells (MSCs) transplantation can improve the metabolic profiles of diabetic animal models. However the exact mechanisms of reversing hyperglycemia remain to be elusive. Trans-differentiation of MSCs into insulin-producing cells (IPCs) has ever been regarded as the main mechanism. But other reports have contradicted these findings and it is difficult to explain the timing and extent of improvement by only the effect through trans-differentiation. Researches have found that MSCs naturally produce a variety of cytokines and growth factors, promoting the survival of surrounding cells, called as paracrine mechanisms. Paracrine effects have been proved to play an important role in tissue regeneration and repair in recent researches. Therefore we speculate that MSCs transplantation into diabetic animals may prevent apoptosis of injured pancreatic beta cells and enhance regeneration of endogenous progenitor cells through paracrine actions such as angiogenic, cytoprotective, anti-inflammatory, mitogenic and anti-apoptotic effects. This hypothesis, if proved to be valid, may represent an important breakthrough in developing effective molecular or genetic therapeutics for diabetes.

[Effect of source-sink ratio changing on yield formation of Cynanchum bungei].

OBJECTIVE: To study the effect of changing source-sink ratio on dry matter accumulation yield, distribution and interrelated physiological index of Cynanchum bungei. METHOD: Bud, fruit or side tress of C. bungei were picked artificially in the development stage. LAI, chlorophyll content, photosynthesis of single leaf, accumulation and distribution of dry matter at different and treatments were measured. The untreated plant was used as the control. RESULT: Although leaf decrease can be compensated by the increasing photosynthesis rate of single leaf, the LAI was small, chlorophyll decomposes quickly and these leaves showed the signs of early ageing. The matter accumulation was lower than that of control. Picking bud and fruit made photosynthesis rate of single leaf descend, chlorophyll decomposes slowly and its content keeps high, that inhibited ageing of the plant obviously. The LAI keeps larger, photosynthate was abundant. Dry matter accumulation and distribution to the root were higher than that of control and that of side tress picked. So, the yield with this treatment increased. CONCLUSION: Picking bud can increase LAI, postpone the decomposition of chlorophyll, and protract the functional leaves. Consequently, picking bud can add the accumulation of dry matter, increase proportion to radix and improve the yield and economy benefit.

Comparison of continuous subcutaneous insulin infusion and insulin glargine-based multiple daily insulin aspart injections with preferential adjustment of basal insulin in patients with type 2 diabetes.

The purpose of this study was to evaluate and compare multiple daily injection (MDI) therapy of bolus insulin aspart and basal insulin glargine with continuous subcutaneous insulin infusion (CSII) with aspart in patients with type 2 diabetes mellitus (T2DM). It was assessed whether MDI was capable of controlling glycemic index with a higher efficacy than CSII by preferential adjustment of basal insulin with a lower total daily insulin dosage in T2DM. Two hundred patients with T2DM were enrolled in the study and randomly assigned to CSII (n=100) and MDI (n=100; aspart immediately prior to each meal and glargine at bedtime) groups for 12 weeks of therapy. During the last week of each treatment period, the subjects wore a continuous glucose monitoring system for 2-3 days. The dosage of basal insulin was preferentially adjusted to control prior-meal blood glucose levels, and the characteristics of insulin dosage were analyzed. No statistically significant differences were observed between the two groups in hemoglobin A1c (HbA1c), which dropped from 10-11% prior to therapy to 7-7.5% after 12 weeks. After 12 weeks, good glycemic level control was achieved in all patients in the MDI and CSII groups. A statistically significant difference in the dose of insulin between the CSII and MDI groups was observed (P<0.001). In conclusion, no significant differences were found between the two therapies in the incidence of hypoglycemia and HbA1c for the 12 weeks. The basal insulin dosage was significantly decreased in the MDI group compared with that in the CSII group, but the CSII group was superior to MDI group in decreasing fasting blood glucose and shortening the time required for hypoglycemia to meet the targeted level.

Investigation of the insulin dose and characteristics of continuous subcutaneous insulin infusion in Chinese people with type 2 diabetes.

BACKGROUND: Continuous subcutaneous insulin infusion (CSII) for type 2 diabetes mellitus (T2DM) is a promising therapy. CSII therapy is flexible, but the required insulin dose for different people may vary. Few studies have investigated the insulin dose and characteristics of CSII for T2DM, and none has focused on an Asian Chinese population. METHODS: In total, 171 subjects with T2DM were using CSII and divided into different groups according to their body mass index (BMI) and the course of disease, respectively. The basal rate of CSII was set for four periods per day. We preferentially adjusted the basal insulin dose to control fasting and preprandial blood glucose. RESULTS: Good glycemic control was achieved after 4.8±2.5 days. The mean total daily insulin dose was 31.66±9.85 IU, and the dose per unit body weight was 0.48±0.19 IU/kg/day. The total daily basal and bolus doses were 21.14±7.64 IU and 10.38±3.62 IU, respectively (i.e., about 66.7±6.8% and 33.3±6.8% of the total daily dose). We did not observe any significant difference in total dose of insulin or basal and bolus doses of insulin per day among different groups divided by BMI. Only in the group with BMI of <23 kg/m(2) was the insulin dose of per kilogram of body weight (0.60±0.25 IU/kg/day) significantly higher than in the other two groups (P=0.0001). There was no relationship between the insulin dose and the course of disease. CONCLUSIONS: In individuals with T2DM on CSII short-term intensive therapy, proper increase of basal dose of insulin and preferential adjustment of the basal rate may be the effective method that can achieve good glycemic control with a lower total daily dose.