One-pot selective biosynthesis of Tyrian purple in Escherichia coli.

Tyrian purple (6,6'-Dibromoindigo) is an ancient precious dye, which possesses remarkable properties as a biocompatible semiconductor material. Recently, biosynthesis has emerged as an alternative for the sustainable production of Tyrian purple from a natural substrate. However, the selectivity issue in enzymatic tryptophan (Trp) and bromotryptophan (6-Br-Trp) degradation was an obstacle for obtaining high-purity Tyrian purple in a single cell biosynthesis. In this study, we present a simplified one-pot process for the production of Tyrian purple from Trp in Escherichia coli (E. coli) using Trp 6-halogenase from Streptomyces toxytricini (SttH), tryptophanase from E. coli (TnaA) and a two-component indole oxygenase from Providencia Rettgeri GS-2 (GS-C and GS-D). To enhance the in vivo solubility and activity of SttH and flavin reductase (Fre) fusion enzyme (Fre-L3-SttH), a chaperone system of GroEL/GroES (pGro7) was introduced in addition to the implementation of a set of optimization strategies, including fine-tuning the expression vector, medium, concentration of bromide salt and inducer. To overcome the selectivity issue and achieve a higher conversion yield of Tyrian purple with minimal indigo formation, we applied the λpL/pR-cI857 thermoinducible system to temporally control the bifunctional fusion enzyme of TnaA and monooxygenase GS-C (TnaA-L3-GS-C). Through optimization of the fermentation process, we were able to achieve a Tyrian purple titer of 44.5 mg L-1 with minimal indigo byproduct from 500 µM Trp. To the best of our knowledge, this is the first report of the selective production of Tyrian purple in E. colivia a one-pot process.

Clinical differences in chest CT characteristics between the progression and remission stages of patients with COVID-19 pneumonia.

INTRODUCTION: Computed tomography (CT) can be effective for the early screening and diagnosis of COVID-19. This study aimed to investigate the distinctive CT characteristics of two stages of the disease (progression and remission). METHODS: We included all COVID-19 patients admitted to Wenzhou Central Hospital from January to February, 2020. Patients underwent multiple chest CT scans at intervals of 3-10 days. CT features were recorded, such as the lesion lobe, distribution characteristics (subpleural, scattered or diffused), shape of the lesion, maximum size of the lesion, lesion morphology (ground-glass opacity, GGO) and consolidation features. When consolidation was positive, the boundary was identified to determine its clarity. RESULTS: The ratios of some representative features differed between the remission stage and the progression phase, such as round-shape lesion (8.0% vs 34.4%), GGO (65.0% vs 87.5%), consolidation (62.0% vs 31.3%), large cable sign (59.0% vs 9.4%) and crazy-paving sign (20.0% vs 50.0%). Using these features, we pooled all the CT data (n = 132) and established a logistic regression model to predict the current development stage. The variables consolidation, boundary feature, large cable sign and crazy-paving sign were the most significant factors, based on a variable named "prediction of progression or remission" (PPR) that we constructed. The ROC curve showed that PPR had an AUC of 0.882 (cutoff value = 0.66, sensitivity = 0.75, specificity = 0.875). CONCLUSION: CT characteristics, in particular, round shape, GGO, consolidation, large cable sign, and crazy-paving sign, may increase the recognition of the intrapulmonary development of COVID-19.

Combining retinal-based and chlorophyll-based (oxygenic) photosynthesis: Proteorhodopsin expression increases growth rate and fitness of a ∆PSI strain of Synechocystis sp. PCC6803.

To fill the "green absorption gap", a green absorbing proteorhodopsin was expressed in a PSI-deletion strain (ΔPSI) of Synechocystis sp. PCC6803. Growth-rate measurements, competition experiments and physiological characterization of the proteorhodopsin-expressing strains, relative to the ΔPSI control strain, allow us to conclude that proteorhodopsin can enhance the rate of photoheterotrophic growth of ΔPSI Synechocystis strain. The physiological characterization included measurement of the amount of residual glucose in the spent medium and analysis of oxygen uptake- and production rates. To explore the use of solar radiation beyond the PAR region, a red-shifted variant Proteorhodopsin-D212N/F234S was expressed in a retinal-deficient PSI-deletion strain (ΔPSI/ΔSynACO). Via exogenous addition of retinal analogue an infrared absorbing pigment (maximally at 740 nm) was reconstituted in vivo. However, upon illumination with 746 nm light, it did not significantly stimulate the growth (rate) of this mutant. The inability of the proteorhodopsin-expressing ΔPSI strain to grow photoautotrophically is most likely due to a kinetic rather than a thermodynamic limitation of its NADPH-dehydrogenase in NADP+-reduction.

On the use of oxygenic photosynthesis for the sustainable production of commodity chemicals.

A sustainable society will have to largely refrain from the use of fossil carbon deposits. In such a regime, renewable electricity can be harvested as a primary source of energy. However, as for the synthesis of carbon-based materials from bulk chemicals, an alternative is required. A sustainable approach towards this is the synthesis of commodity chemicals from CO2 , water and sunlight. Multiple paths to achieve this have been designed and tested in the domains of chemistry and biology. In the latter, the use of both chemotrophic and phototrophic organisms has been advocated. 'Direct conversion' of CO2 and H2 O, catalyzed by an oxyphototroph, has excellent prospects to become the most economically competitive of these transformations, because of the relative ease of scale-up of this process. Significantly, for a wide range of energy and commodity products, a proof of principle via engineering of the corresponding production organism has been provided. In the optimization of a cyanobacterial production organism, a wide range of aspects has to be addressed. Of these, here we will put our focus on: (1) optimizing the (carbon) flux to the desired product; (2) increasing the genetic stability of the producing organism and (3) maximizing its energy conversion efficiency. Significant advances have been made on all these three aspects during the past 2 years and these will be discussed: (1) increasing the carbon partitioning to >50%; (2) aligning product formation with the growth of the cells and (3) expanding the photosynthetically active radiation region for oxygenic photosynthesis.

Deletion of sll1541 in Synechocystis sp. Strain PCC 6803 Allows Formation of a Far-Red-Shifted holo-Proteorhodopsin In Vivo.

In many pro- and eukaryotes, a retinal-based proton pump equips the cell to drive ATP synthesis with (sun)light. Such pumps, therefore, have been proposed as a plug-in for cyanobacteria to artificially increase the efficiency of oxygenic photosynthesis. However, little information on the metabolism of retinal, their chromophore, is available for these organisms. We have studied the in vivo roles of five genes (sll1541, slr1648, slr0091, slr1192, and slr0574) potentially involved in retinal metabolism in Synechocystis sp. strain PCC 6803. With a gene deletion approach, we have shown that Synechocystis apo-carotenoid-15,15-oxygenase (SynACO), encoded by gene sll1541, is an indispensable enzyme for retinal synthesis in Synechocystis, presumably via asymmetric cleavage of ß-apo-carotenal. The second carotenoid oxygenase (SynDiox2), encoded by gene slr1648, competes with SynACO for substrate(s) but only measurably contributes to retinal biosynthesis in stationary phase via an as-yet-unknown mechanism. In vivo degradation of retinal may proceed through spontaneous chemical oxidation and via enzyme-catalyzed processes. Deletion of gene slr0574 (encoding CYP120A1), but not of slr0091 or of slr1192, causes an increase (relative to the level in wild-type Synechocystis) in the retinal content in both the linear and stationary growth phases. These results suggest that CYP120A1 does contribute to retinal degradation. Preliminary data obtained using 13C-labeled retinal suggest that conversion to retinol and retinoic acid and subsequent further oxidation also play a role. Deletion of sll1541 leads to deficiency in retinal synthesis and allows the in vivo reconstitution of far-red-absorbing holo-proteorhodopsin with exogenous retinal analogues, as demonstrated here for all-trans 3,4-dehydroretinal and 3-methylamino-16-nor-1,2,3,4-didehydroretinal.IMPORTANCE Retinal is formed by many cyanobacteria and has a critical role in most forms of life for processes such as photoreception, growth, and stress survival. However, the metabolic pathways in cyanobacteria for synthesis and degradation of retinal are poorly understood. In this paper we identify genes involved in its synthesis, characterize their role, and provide an initial characterization of the pathway of its degradation. This led to the identification of sll1541 (encoding SynACO) as the essential gene for retinal synthesis. Multiple pathways for retinal degradation presumably exist. These results have allowed us to construct a strain that expresses a light-dependent proton pump with an action spectrum extending beyond 700 nm. The availability of this strain will be important for further work aimed at increasing the overall efficiency of oxygenic photosynthesis.

Retinal-Based Proton Pumping in the Near Infrared.

Proteorhodopsin (PR) and Gloeobacter rhodopsin (GR) are retinal-based light-driven proton pumps that absorb visible light (maxima at 520-540 nm). Shifting the action spectra of these proton pumps beyond 700 nm would generate new prospects in optogenetics, membrane sensor technology, and complementation of oxygenic phototrophy. We therefore investigated the effect of red-shifting analogues of retinal, combined with red-shifting mutations, on the spectral properties and pump activity of the resulting pigments. We investigated a variety of analogues, including many novel ones. One of the novel analogues we tested, 3-methylamino-16-nor-1,2,3,4-didehydroretinal (MMAR), produced exciting results. This analogue red-shifted all of the rhodopsin variants tested, accompanied by a strong broadening of the absorbance band, tailing out to 850-950 nm. In particular, MMAR showed a strong synergistic effect with the PR-D212N,F234S double mutant, inducing an astonishing 200 nm red shift in the absorbance maximum. To our knowledge, this is by far the largest red shift reported for any retinal protein. Very importantly, all MMAR-containing holoproteins are the first rhodopsins retaining significant pump activity under near-infrared illumination (730 nm light-emitting diode). Such MMAR-based rhodopsin variants present very promising opportunities for further synthetic biology modification and for a variety of biotechnological and biophysical applications.

Expression of holo-proteorhodopsin in Synechocystis sp. PCC 6803.

Retinal-based photosynthesis may contribute to the free energy conversion needed for growth of an organism carrying out oxygenic photosynthesis, like a cyanobacterium. After optimization, this may even enhance the overall efficiency of phototrophic growth of such organisms in sustainability applications. As a first step towards this, we here report on functional expression of the archetype proteorhodopsin in Synechocystis sp. PCC 6803. Upon use of the moderate-strength psbA2 promoter, holo-proteorhodopsin is expressed in this cyanobacterium, at a level of up to 10(5) molecules per cell, presumably in a hexameric quaternary structure, and with approximately equal distribution (on a protein-content basis) over the thylakoid and the cytoplasmic membrane fraction. These results also demonstrate that Synechocystis sp. PCC 6803 has the capacity to synthesize all-trans-retinal. Expressing a substantial amount of a heterologous opsin membrane protein causes a substantial growth retardation Synechocystis, as is clear from a strain expressing PROPS, a non-pumping mutant derivative of proteorhodopsin. Relative to this latter strain, proteorhodopsin expression, however, measurably stimulates its growth.

Modulation of spectral properties and pump activity of proteorhodopsins by retinal analogues.

Proteorhodopsins are heptahelical membrane proteins which function as light-driven proton pumps. They use all-trans-retinal A1 as a ligand and chromophore and absorb visible light (520-540 nm). In the present paper, we describe modulation of the absorbance band of the proteorhodopsin from Monterey Bay SAR 86 gammaproteobacteria (PR), its red-shifted double mutant PR-D212N/F234S (PR-DNFS) and Gloeobacter rhodopsin (GR). This was approached using three analogues of all-trans-retinal A1, which differ in their electronic and conformational properties: all-trans-6,7-s-trans-locked retinal A1, all-trans-phenyl-retinal A1 and all-trans-retinal A2. We further probed the effect of these retinal analogues on the proton pump activity of the proteorhodopsins. Our results indicate that, whereas the constraints of the retinal-binding pocket differ for the proteorhodopsins, at least two of the retinal analogues are capable of shifting the absorbance bands of the pigments either bathochromically or hypsochromically, while maintaining their proton pump activity. Furthermore, the shifts implemented by the analogues add up to the shift induced by the double mutation in PR-DNFS. This type of chromophore substitution may present attractive applications in the field of optogenetics, towards increasing the flexibility of optogenetic tools or for membrane potential probes.

Increased levels of lactate dehydrogenase and hypertension are associated with severe illness of COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is amid an ongoing pandemic. It has been shown that patients with cardiovascular comorbidities are at higher risk of severe illness of COVID-19. AIM: To find out the relationship between cardiovascular comorbidities and severe illness of COVID-19. METHODS: The clinical data of 140 COVID-19 patients treated from January 22, 2020 to March 3, 2020 at our hospital were retrospectively collected. The clinical characteristics were compared between patients with mild illness and those with severe illness. RESULTS: There were 75 male patients and 65 female patients (53.6% vs 46.4%). The mean age was 45.4 ± 14.6 years (range, 2-85 years). Most of the patients had mild illness (n = 114, 81.4%) and 26 patients had severe illness (18.6%). The most common symptom was fever (n = 110, 78.6%), followed by cough (n = 82, 58.6%) and expectoration (n = 51, 36.4%). Eight patients were asymptomatic but were positive for severe acute respiratory syndrome coronavirus 2 RNA. Patients with severe illness were significantly more likely to be hypertensive than those with mild illness [(10/26, 38.4%) vs (22/114, 19.3%), P = 0.036]. The levels of lactate dehydrogenase were significantly higher in the severe illness group than in the mild illness group (299.35 ± 68.82 vs 202.94 ± 63.87, P < 0.001). No patient died in either the severe illness or the mild illness group. CONCLUSION: Hypertension and elevated levels of lactate dehydrogenase may be associated with severe illness of COVID-19.

[Testing methods for seed quality of Cyathula officinalis].

OBJECTIVE: To study testing methods of seed quality, and provide a basis for establishing seed testing specification of Cyathula officinalis. METHOD: Referring to the Specifications for Agricultural Seed Testing, the optimal testing methods of seed quality of C. officinalis were screened. RESULT AND CONCLUSION: The testing method for C. officinalis seed quality has been initially established. At least 8 g seeds should be sampled and passed through 20-mesh sieve for purity analysis. The phenotypic observation and size measurement were used for authenticity testing. The seeds were inoculated directly on PDA medium, cultured 5 days on 28 degrees C for seed health testing. The weight of 1 000 seeds was determined by using the 500-seed method. The water content of the seeds was determined under the higher temperature (133 +/- 2) degrees C for 3 hours. The seeds were dipped into 0.1% TTC solution 3 hours for determining viability. The seeds were cultured on pleated paper at 25 degrees C for 2-9 days for germination testing.

Correlation Analysis Between Serum Uric Acid, Prealbumin Level, Lactate Dehydrogenase, and Severity of COVID-19.

Objective: To analyze the correlation between serum uric acid, prealbumin levels, lactate dehydrogenase (LDH), and the severity of COVID-19. Methods: The data from 135 patients with COVID-19 was collected, and the patients were divided into a non-severe group (110 cases) and a severe group (25 cases), according to the severity of illness. Sixty cases with normal physical examinations over the same period and 17 cases diagnosed with other viral pneumonia in the past five years were selected as the control group to analyze the correlation between the detection index and the severity of COVID-19. Results: Serum albumin and prealbumin in the severe group were significantly lower than those in the non-severe group (p < 0.01); serum uric acid in the severe group was lower than that in the non-severe group (p < 0.05). LDH and C-reaction protein (CRP) in the severe group were higher than those in non-severe group (p < 0.01); the levels of albumin, prealbumin, serum uric acid, and LDH in the severe group were significantly different from those in healthy control group (p < 0.01) and the levels of prealbumin, serum uric acid, LDH, and CRP in the severe group were significantly different from those in the other viral pneumonia group (p < 0.01). Serum albumin and prealbumin were positively correlated with the oxygenation index (p < 0.001), while LDH was negatively correlated with oxygenation index (p < 0.001). Conclusion: Serum albumin, prealbumin, the oxygenation index, and LDH are risk factors of COVID-19.

Construction and Comparison of ceRNA Regulatory Network for Different Age Female Breast Cancer.

Studies have shown the difference appearing among the prognosis of patients in different age groups. However, the molecular mechanism implicated in this disparity have not been elaborated. In this study, expression profiles of female breast cancer (BRCA) associated mRNAs, lncRNAs and miRNAs were downloaded from the TCGA database. The sample were manually classified into three groups according to their age at initial pathological diagnosis: young (age ≤ 39 years), elderly (age ≥ 65 years), and intermediate (age 40-64 years). lncRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) network was respectively constructed for different age BRCA. Then, the biological functions of differentially expressed mRNAs (DEmRNAs) in ceRNA network were further investigated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Finally, survival analysis was used to identify prognostic biomarkers for different age BRCA patients. We identified 13 RNAs, 38 RNAs and 40 RNAs specific to patients aged ≤ 39 years, aged 40-64 years, and aged ≥ 65 years, respectively. Furthermore, the unique pathways were mainly enriched in cytokine-cytokine receptor interaction in patients aged 40-64 years, and were mainly enriched in TGF-beta signaling pathway in patients aged ≥ 65 years. According to the survival analysis, AGAP11, has-mir-301b, and OSR1 were respectively functioned as prognostic biomarkers in young, intermediate, and elderly group. In summary, our study identified the differences in the ceRNA regulatory networks and provides an effective bioinformatics basis for further understanding of the pathogenesis and predicting outcomes for different age BRCA.

Membrane matters: The impact of a nanodisc-bilayer or a detergent microenvironment on the properties of two eubacterial rhodopsins.

Multi-spanning membrane proteins usually require solubilization to allow proper purification and characterization, which generally impairs their structural and functional integrity. We have tested the efficacy of several commonly used detergents and membrane-mimicking nanodiscs with respect to solubilization, spectral properties, thermal stability and oligomeric profile of two membrane proteins from the eubacterial rhodopsin family, green proteorhodopsin (PR) and Gloeobacter violaceus rhodopsin (GR). Good solubilization was observed for the detergents TritonX-100 and dodecylphosphocholine (DPC), but DPC in particular strongly affected the thermal stability of PR and especially GR. The least deleterious effects were obtained with n-dodecyl-ß-D-maltopyranoside (DDM) and octyl glucose neopentyl glycol (OGNG), which adequately stabilized the native oligomeric and monomeric state of PR and GR, respectively. The transition from the oligomeric to the monomeric state is accompanied by a small red-shift. Both GR and PR were rather unstable in SMA-nanodiscs, but the highest thermal stability was realized by the MSP-nanodisc environment. The size of the MSP-nanodisc was too small to fit the PR hexamer, but large enough to contain the PR monomer and GR trimer. This permitted the comparison of the photocycle of trimeric GR in a membrane-mimicking (MSP-nanodisc) and a detergent (DDM) environment. The ultrarapid early phase of the photocycle (femto- to picosecond lifetimes) showed very similar kinetics in either environment, but the slower part, initiated with proton transfer and generation of the M intermediate, proceeded faster in the nanodisc environment. The implications of our results for the biophysical characterization of PR and GR are discussed.

[Piezoelectric property of novel biological piezoelectric ceramic HALNK and its effect on the functional expression of rat osteoblast cells].

OBJECTIVE: To test the Piezoelectric property of novel biological piezoelectric ceramic HALNK and its effect on the proliferation and differentiation of rat osteoblast cells. METHODS: The biological piezoelectric ceramic HALNK1/9 and HALNK5/5 were prepared by mixing Hydroxyapatite (HA) with lithium sodium potassium niobate (LNK) piezoelectric ceramic at a ratio of 1/9 and 5/5 (wt/wt), respectively. After poling treatment, the piezoelectric constants were measured. The osteoblast cells were then seeded on the surfaces of HALNK. The proliferation and differentiation activities of the osteoblast cells were evaluated by MTT assays, ALP activities and scanning electron microscopy examinations. RESULTS: Cells grown on the surfaces of HALNK showed normal morphology, and had better proliferation and differentiation activities than the control. The growth of osteoblastic cells on the surface of HALNK1/9 was significantly better than others. CONCLUSION: The surface of HALNK 1/9 possesses better piezoelectric property and osteogenesis potential than HALNK5/5.

The clinical application value of multi-slice spiral CT enhanced scans combined with multiplanar reformations images in preoperative T staging of rectal cancer.

This study aims to evaluate the diagnostic accuracy and clinical application value of multi-slice spiral CT (MSCT) enhanced scans combined with multiplanar reformations (MPRs) images compared with postoperative pathological results in preoperative T staging of rectal cancer.One hundred sixty-eight consecutive patients with rectal cancer were admitted in our hospital between January 2013 and October 2018. Conventional MSCT plain scans, multi-phase dynamic contrast-enhanced scans, and MPRs were performed in all patients before surgical operation. The preoperative T staging of the rectal cancer lesions was evaluated using MSCT enhanced scans combined with MPRs, which was verified by postoperative pathological results. The diagnostic accuracy of MSCT enhanced scans combined with MPRs in evaluating T staging of the rectal cancer lesions were analyzed by χ test and Kappa test.Compared with postoperative pathology, T staging using MSCT enhanced scans combined with MPRs had overall accuracy of 85.7%. Consistency between MSCT enhanced scans combined with MPRs and postoperative pathological staging was effective for T staging (Kappa = 0.658, χ = 4.200, P = .122).Conventional MSCT enhanced scans combined with MPRs are simple and feasible. It is consistent with the pathological diagnosis of evaluating T staging in the rectal cancer lesions. It can provide reliable imaging evidence for the preoperative evaluation of primary rectal cancer, especially in patients with magnetic resonance imaging (MRI) contraindications, or in grass-roots hospitals due to lack of MRI equipment.

Redshifted and Near-infrared Active Analog Pigments Based upon Archaerhodopsin-3.

Archaerhodopsin-3 (AR3) is a member of the microbial rhodopsin family of hepta-helical transmembrane proteins, containing a covalently bound molecule of all-trans retinal as a chromophore. It displays an absorbance band in the visible region of the solar spectrum (λmax 556 nm) and functions as a light-driven proton pump in the archaeon Halorubrum sodomense. AR3 and its mutants are widely used in neuroscience as optogenetic neural silencers and in particular as fluorescent indicators of transmembrane potential. In this study, we investigated the effect of analogs of the native ligand all-trans retinal A1 on the spectral properties and proton-pumping activity of AR3 and its single mutant AR3 (F229S). While, surprisingly, the 3-methoxyretinal A2 analog did not redshift the absorbance maximum of AR3, the analogs retinal A2 and 3-methylamino-16-nor-1,2,3,4-didehydroretinal (MMAR) did generate active redshifted AR3 pigments. The MMAR analog pigments could even be activated by near-infrared light. Furthermore, the MMAR pigments showed strongly enhanced fluorescence with an emission band in the near-infrared peaking around 815 nm. We anticipate that the AR3 pigments generated in this study have widespread potential for near-infrared exploitation as fluorescent voltage-gated sensors in optogenetics and artificial leafs and as proton pumps in bioenergy-based applications.

Functional Expression of Gloeobacter Rhodopsin in PSI-Less Synechocystis sp. PCC6803.

The approach of providing an oxygenic photosynthetic organism with a cyclic electron transfer system, i.e., a far-red light-driven proton pump, is widely proposed to maximize photosynthetic efficiency via expanding the absorption spectrum of photosynthetically active radiation. As a first step in this approach, Gloeobacter rhodopsin was expressed in a PSI-deletion strain of Synechocystis sp. PCC6803. Functional expression of Gloeobacter rhodopsin, in contrast to Proteorhodopsin, did not stimulate the rate of photoheterotrophic growth of this Synechocystis strain, analyzed with growth rate measurements and competition experiments. Nevertheless, analysis of oxygen uptake and-production rates of the Gloeobacter rhodopsin-expressing strains, relative to the ΔPSI control strain, confirm that the proton-pumping Gloeobacter rhodopsin provides the cells with additional capacity to generate proton motive force. Significantly, expression of the Gloeobacter rhodopsin did modulate levels of pigment formation in the transgenic strain.

Functional Expression of Gloeobacter Rhodopsin in Synechocystis sp. PCC6803.

Proteorhodopsins are light-driven proton pumps that occur widespread in Nature, where they function predominantly in environments with high incident irradiance. Their maximal absorbance is usually in the blue range, but can be extended into the (far)red range of the electromagnetic spectrum. Because they can be expressed heterologously, they may be exploited in studies aimed at increasing the efficiency of photosynthesis. Here we report further studies toward this goal, by comparing the expression of two different bacterial rhodopsins (Proteorhodopsin and Gloeobacter rhodopsin) in the model cyanobacterium Synechocystis sp. PCC6803. In particular, we investigated the pigments bound by the respective apo-opsins, and the oligomeric state of the corresponding holo-rhodopsins, both in Escherichia coli and in the cyanobacterial membranes. We conclude that the two proton-pumping rhodopsins are predominantly present in an oligomeric state (hexamers for Proteorhodopsin and trimers for Gloeobacter rhodopsin). Furthermore, Gloeobacter rhodopsin is able to bind an antenna carotenoid (in addition to retinal) and has the highest pumping rate at given light intensity. However, its lower expression level will decrease its physiological effectiveness. It remains to be established which of these two bacterial rhodopsins is best in stimulating the growth rate of its cyanobacterial host.

Endophytic fungus strain 28 isolated from Houttuynia cordata possesses wide-spectrum antifungal activity.

The aim of this paper is to identify and investigate an endophytic fungus (strain 28) that was isolated from Houttuynia cordata Thunb, a famous and widely-used Traditional Chinese Medicine. Based on morphological methods and a phylogenetic analysis of ITS sequences, this strain was identified as Chaetomium globosum. An antifungal activity bioassay demonstrated that the crude ethyl acetate (EtOAc) extracts of strain 28 had a wide antifungal spectrum and strong antimicrobial activity, particularly against Exserohilum turcicum (Pass.) Leonard et Suggs, Botrytis cinerea persoon and Botrytis cinerea Pers. ex Fr. Furthermore, the fermentation conditions, extraction method and the heat stability of antifungal substances from strain 28 were also studied. The results showed that optimal antifungal activity can be obtained with the following parameters: using potato dextrose broth (PDB) as the base culture medium, fermentation for 4-8d (initial pH: 7.5), followed by extraction with EtOAc. The extract was stable at temperatures up to 80°C. This is the first report on the isolation of endophytic C. globosum from H. cordata to identify potential alternative biocontrol agents that could provide new opportunities for practical applications involving H. cordata.

Effect of metformin on global gene expression in liver of KKAy mice.

BACKGROUND: Metformin is a first-line drug for treating type 2 diabetes mellitus, yet its mechanism remains only partially understood and controversial. In this study we assessed a global gene expression profiling in liver of KKAy mice affected by metformin. This study aimed to identify the novel anti-diabetic mechanisms of metformin. METHODS: After KKAy mice were administered metformin for 5 weeks, the gene changes profile in the livers of KKAy mice were assessed by using the Agilent whole mice genome oligo microarray. RESULTS: Metformin altered the gene expression profiles in liver of KKAy mice. To our best knowledge, some genes have not been reported until now, such as Anxa2, Atf6, and so on. These genes were involved in many pathways, such as peroxisome proliferator activated receptor signaling pathway. CONCLUSIONS: Gene expression changes induced by metformin were in support of the improvement of glucolipid metabolism and insulin resistance in KKAy mice. These findings expanded our knowledge of pharmacological action of metformin, and provided the potential novel insights and interesting information about the molecules involved in the antidiabetic effects of metformin.