Engineering Escherichia coli for high-yielding 2,5-Dimethylpyrazine synthesis from L-Threonine by reconstructing metabolic pathways and enhancing cofactors regeneration.

2,5-Dimethylpyrazine (2,5-DMP) is important pharmaceutical raw material and food flavoring agent. Recently, engineering microbes to produce 2,5-DMP has become an attractive alternative to chemical synthesis approach. In this study, metabolic engineering strategies were used to optimize the modified Escherichia coli BL21 (DE3) strain for efficient synthesis of 2,5-DMP using L-threonine dehydrogenase (EcTDH) from Escherichia coli BL21, NADH oxidase (EhNOX) from Enterococcus hirae, aminoacetone oxidase (ScAAO) from Streptococcus cristatus and L-threonine transporter protein (EcSstT) from Escherichia coli BL21, respectively. We further optimized the reaction conditions for synthesizing 2,5-DMP. In optimized conditions, the modified strain can convert L-threonine to obtain 2,5-DMP with a yield of 2897.30 mg/L. Therefore, the strategies used in this study contribute to the development of high-level cell factories for 2,5-DMP.

Two new Erythrobasidium species inhabiting the phyllosphere discovered in the Baotianman Nature Reserve in China.

The genus Erythrobasidium is kind of species-scarce and undersampling basidiomycetes. Currently, only six species have been accepted into the genus and the diversity still remains incompletely understood. In this study, five Erythrobasidium strains were isolated in the surface of plant leaves collected from the Baotianman Nature Reserve, Henan Province, central China. Phylogenetic analyses of the small ribosomal subunit (SSU) rRNA gene, the internal transcribed spacer (ITS) region, the D1/D2 domain of the large subunit (LSU) rRNA gene, and the translation elongation factor 1-α (TEF1-α) gene coupled with morphological studies were employed to characterize and identify these isolates. As a result of these, two new species, namely E. turpiniae sp. nov. and E. nanyangense sp. nov., were delimited and proposed based on morphological and molecular evidence. A detailed description and illustration of both new species, as well as their differences with the close relatives in the genus are provided. An identification key for Erythrobasidium species is also provided. This study provides further insights into our understanding of Erythrobasidium species.

Two new phyllospheric species of Colacogloea (Colacogloeaceae, Pucciniomycotina) identified in China.

During our ongoing survey of basidiomycetous yeasts associated with plant leaves in virgin forest, five Colacogloea strains were isolated in the Baotianman Nature Reserve, Henan Province, central China. Phenotypes from cultures and a phylogeny based on the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) rRNA gene were employed to characterize and identify these isolates. As a result, two new species, namely Colacogloeaceltidissp. nov. and C.pararetinophilasp. nov., are introduced herein. In the phylogeny of combined ITS and LSU dataset, the new species C.celtidissp. nov. formed a clade with the unpublished Colacogloea strain (KBP: Y-6832), and together these formed the sister group to C.armeniacae, while C.pararetinophilasp. nov. was retrieved as a sister to C.retinophila. A detailed description and illustration of both new species, as well as the differences between them and their closest relatives in the genus are provided. Results from the present study will add to our knowledge of the biodiversity of Colacogloea in China.

Predesign of Catalytically Active Sites via Stable Coordination Cluster Model System for Electroreduction of CO2 to Ethylene.

Purposefully designing the well-defined catalysts for the selective electroreduction of CO2 to C2 H4 is an extremely important but challenging work. In this work, three crystalline trinuclear copper clusters (Cu3 -X, X=Cl- , Br- , NO3 - ) have been designed, containing three active Cu sites with the identical coordination environment and appropriate spatial distance, delivering high selectivity for the electrocatalytic reduction of CO2 to C2 H4 . The highest faradaic efficiency of Cu3 -X for CO2 -to-C2 H4 conversion can be adjusted from 31.90 % to 55.01 % by simply replacing the counter anions (NO3 - , Cl- , Br- ). The DFT calculation results verify that Cu3 -X can facilitate the C-C coupling of identical *CHO intermediates, subsequently forming molecular symmetrical C2 H4 product. This work provides an important molecular model system and a new design perspective for electroreduction of CO2 to C2 products with symmetrical molecular structure.

A well-defined dual Mn-site based metal-organic framework to promote CO2 reduction/evolution in Li-CO2 batteries.

A series of Li-CO2 battery cathode materials are reported based on metal-organic frameworks with dual-metal sites containing a metalloporphyrin and a metal-coordinated pyrazole. MnTPzP-Mn demonstrates a low voltage hysteresis of 1.05 V at 100 mA g-1 and good stability of 90 cycles at 200 mA g-1. Among them, the Mn-coordinated pyrazole site can promote the effective decomposition of Li2CO3, and the Mn-metalloporphyrin site contributes to the activation of CO2. This is the first example of using a crystalline cathode material with a well-defined structure to reveal natural catalytic sites for CO2 reduction/evolution reactions under aprotic conditions in Li-CO2 batteries.

Expression of Novel L-Leucine Dehydrogenase and High-Level Production of L-Tert-Leucine Catalyzed by Engineered Escherichia coli.

Leucine dehydrogenase (LDH) is a NAD+-dependent oxidoreductase, which can selectively catalyze α-keto acids to obtain α-amino acids and their derivatives. It plays a key role in the biosynthesis of L-tert-leucine (L-Tle). As a non-naturally chiral amino acid, L-Tle can be used as an animal feed additive, nutrition fortifier, which is a perspective and important building block in the pharmaceutical, cosmetic, and food additive industry. In this study, four hypothetical leucine dehydrogenases were discovered by using genome mining technology, using the highly active leucine dehydrogenase LsLeuDH as a probe. These four leucine dehydrogenases were expressed in Escherichia coli BL21(DE3), respectively, and purified to homogeneity and characterized. Compared with the other enzymes, the specific activity of PfLeuDH also shows stronger advantage. In addition, the highly selective biosynthesis of L-Tle from trimethylpyruvic acid (TMP) was successfully carried out by whole-cell catalysis using engineered E. coli cells as biocatalyst, which can efficiently coexpress leucine dehydrogenase and formate dehydrogenase. One hundred-millimolar TMP was catalyzed for 25 h, and the yield and space-time yield of L-Tle reached 87.38% (e.e. >99.99%) and 10.90 g L-1 day-1. In short, this research has initially achieved the biosynthesis of L-Tle, laying a solid foundation for the realization of low-cost and large-scale biosynthesis of L-Tle.

[Community structure and leaf trait diversity in a vulnerable species, Phoebe chekiangensis (Lauraceae).] / æ¸å±æ¤ç‰©æµ™æ±Ÿæ¥ ç¾¤è½ç»“æž„åŠå¶ç‰‡æ€§çŠ¶å¤šæ ·æ€§.

Phoebe chekiangensis, as one original species of 'Nanmu with golden tint', harbors limited natural distribution regions, which is recognized as a vulnerable species in China under nationwide protection. Under the background of global climate change, it is of scientific significance to study the community structure and diversity of the natural populations of P. chekiangensis. In this study, community structure, species diversity and the phenotypic variation leaf traits in the communities of thirteen residue natural populations were analyzed. A total of 235 vascular species from 162 genera and 87 families were found in 16 plots within 13 natural populations, including 221 seed plants from 151 genera and 79 families. The species diversity in tree layer of community in Kaihua, Zhejiang and Linan, Zhejiang was significantly lower than that of other communities due to severe disturbance, while intermediate disturbance promoted the species diversity of shrub layer in community in Jianning, Fujian, and slight disturbance was beneficial to natural regeneration of P. chekiangensis. Foliage phenotype was important for species identification within Phoebe genus. There existed substantial variation in foliage phenotypic diversity among and within populations. The mean coefficient of variation was 17.2%, ranging from 10.4% to 27.5%. The variation was greater among populations (53.6%) than within populations (17.0%). Mean phenotypic differentiation coefficient was 75.1% among populations, indicating that the variance among populations was the main source for the phenotypic variation of the species. Results from the cluster analysis indicated that the 13 natural populations were divided into two distinct groups based on the Euclidean distance (10 cm), with stochastic variation.

Whole-genome resequencing reveals candidate mutations for pig prolificacy.

Changes in pig fertility have occurred as a result of domestication, but are not understood at the level of genetic variation. To identify variations potentially responsible for prolificacy, we sequenced the genomes of the highly prolific Taihu pig breed and four control breeds. Genes involved in embryogenesis and morphogenesis were targeted in the Taihu pig, consistent with the morphological differences observed between the Taihu pig and others during pregnancy. Additionally, excessive functional non-coding mutations have been specifically fixed or nearly fixed in the Taihu pig. We focused attention on an oestrogen response element (ERE) within the first intron of the bone morphogenetic protein receptor type-1B gene (BMPR1B) that overlaps with a known quantitative trait locus (QTL) for pig fecundity. Using 242 pigs from 30 different breeds, we confirmed that the genotype of the ERE was nearly fixed in the Taihu pig. ERE function was assessed by luciferase assays, examination of histological sections, chromatin immunoprecipitation, quantitative polymerase chain reactions, and western blots. The results suggest that the ERE may control pig prolificacy via the cis-regulation of BMPR1B expression. This study provides new insight into changes in reproductive performance and highlights the role of non-coding mutations in generating phenotypic diversity between breeds.

Cyberlindnera xishuangbannaensis f.a., sp. nov., a yeast isolated from rotting wood.

Three strains representing a novel species of yeast were isolated from samples of rotting wood collected from Xishuangbanna Tropical Rainforest in Yunnan Province, PR China. Phylogenetic analysis based on the concatenated sequences of the internal transcribed spacer (ITS) region and the D1/D2 domains of the large subunit (LSU) rRNA gene revealed that the novel species is a member of the genus Cyberlindnera, although the formation of ascospores was not observed. The novel species was related most closely to the type strain of the species Candida pattaniensis, but they had a 0.5 % sequence divergence (3 substitutions, 0 gap) in the D1/D2 domain and a 5.4 % sequence divergence (21 substitutions, 10 gaps) in the ITS region. The novel species could also be differentiated from the closely related species by some biochemical and physiological characteristics. The species name Cyberlindnera xishuangbannaensis f.a., sp. nov. is proposed to accommodate these strains, with NYNU 16752T (=CICC 33163T=CBS 14692T) designated as the type strain. The MycoBank number is MB 822199.

Ogataea neixiangensis sp. nov. and Ogataea paraovalis f.a., sp. nov., two methanol-assimilating yeast species isolated from rotting wood.

Four yeast strains were isolated from rotting wood samples collected in the Baotianman Nature Reserve in Henan Province, central China. The sequences of the D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer regions showed that these four strains represent two different undescribed yeast species belonging to the Ogataea clade. Ogataea neixiangensis sp. nov. produces two to four hat-shaped ascospores per ascus, and its closest relative among recognized species is Candida nitratophila. Ogataea paraovalis f.a., sp. nov. is closely related to Candida ovalis but the formation of ascospores was not observed on various sporulation media. The type strain of O. neixiangensis sp. nov. (MycoBank number MB 820697) is NYNU 16951T (=CICC 33166T=CBS 14695T), and the type strain of O. paraovalis f.a., sp. nov. (MycoBank number MB 820698) is NYNU 167106T (=CICC 33168T=CBS 14697T).

[Study of Retrieving the Sandy Surface Roughness Land Based on the Bidirectional Reflectance Model].

In the semiarid area, the structural nature of sandy land is changed due to wind erosion. Furthermore, assessing the changes in the composition and surface roughness in several spatial and temporal scales is significant for the wind erosion model calculations. As a noninvasive approach, remote sensing can be used to improve the study of sandy surface in time and space. In order to characterize the surface structure using the reflectance of sandy land, we analysis the effects of the changes of sandy surface structure on the bidirectional reflectance distribution basing on the multi-angular and hyperspectral measurements in the field; the measured sandy land samples are taken from nature, but the surface structures are artificial: one type is the direction of sand furrows is parallel to the incident direction, the other is the direction of sand furrows is perpendicular to the incident direction. At the same time, we analyzed the effects of surface structure on the bidirectional reflectance factor of sand land and we also retrieve the sandy surface roughness using the reflectance model parameter. The results suggest that both types of sand furrows will influence the distribution of reflectance of sandy land surface, for example, the backward scattering of sandy land increased when the direction of sand furrows is perpendicular to the incident direction, and the range of backward scattering of sandy land expended when the direction of sand furrows is parallel to the incident direction. When we compared the measured reflectance with the modeled results basing on the reflectance model, it is found that the reflectance model can be used to simulate the reflectance property of sandy land surface and prove that the parameter of model is useful for retrieving the surface roughness. This research not only presents the sample for quantifying the structural information of sandy land by the reflectance measurements, but also shows valuable reference for the research of intrinsic optical property of sandy land and the reversion of the texture of sandy land. In other words, this paper can also help the scientists understand the effect of the structural information on the optical properties of sandy land.

[Effects of ligustrazine on extracellular dopamine levels in rat brain dialysate].

Using brain microdialysis and LC-ECD, the content of dopamine in rat brain was detected to investigate the effects of ligustrazine. A liquid chromatography-electrochemical detector method has been established and validated for the determination of dopamine in rat brain dialysate. The results indicate that ligustrazine administration by subcutaneous injection significantly increased dopamine release in rat medial prefrontal cortex, nucleus accumbens and hippocampus in a dose-related manner. The drug's effects on dopa release in rat brain could be directly detected by microdialysis combined with HPLC-ECD and this method has the preponderance over traditional neurology methods.

[Study of hyperspectral polarized reflectance of vegetation canopy at nadir viewing direction].

In the present study, corn canopy is the objective. Firstly the polarization of corn canopy was analyzed based on polarization reflection mechanism; then, the polarization of canopy was measured in different growth period at nadir before heading. The result proved the theoretical derivation that the light reflected from corn canopy is polarized, and found that in the total reflection the polarization light accounts for up to 10%. This shows that polarization measurement provides auxiliary information for remote sensing, but also illustrates that the use of the polarization information retrieval of atmospheric parameters should be considered when the surface polarization affects on it.

[The analysis of polarization of ice based on the multi-angle hyperspectral technique].

In the visible light range, the reflected light of ice contains a portion of polarized light, especially smooth ice often can make the detector obtain the reflection information that contains more polarization information. The fresh water ice and sea ice reflection information was measured, and combined with the angle information and spectral information, the difference in the polarized reflectance characteristics between them was analyzed. It was found that with the polarization degree as index, the difference in the relative reflectance between sea ice and water ice is larger, and at the same time ice shows its unique polarization characteristics. So that the polarization measurements can assist the existing remote sensing technology for better detection of the ice covering the earth's surface.

A non-labeled DNA biosensor based on light addressable potentiometric sensor modified with TiO2 thin film.

Titanium dioxide (TiO(2)) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO(2) thin film by 3-aminopropyltriethoxysilane (APTS), fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO(2) thin film. We found that, with UV irradiation, the silanization level of the irradiated area of the TiO(2) film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO(2) can act as a coating material on the biosensor surface to improve the effect and efficiency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO(2) film. The hybridization of probe DNA and target DNA was monitored by the recording of I-V curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 micromol/L of target DNA sample.

[Study on the modeling of hyperspectral polarized reflection of clove lamina with chlorophyll content].

In the present study, the authors detected clove laminas in different states with multi-angle hyperspectral polarized reflections and measured their chlorophyll content at the same time. The authors analyzed hyperspectral polarized reflections of clove laminas from various viewing zenith angles, incidence angles, the relative azimuth angles, polarized states and chlorophyll content. The authors calculated quantitatively clove laminas in different states with multi-angle hyperspectral polarized reflection by USB2000, bidirectional polarized reflectance and polarized equipment, and built the regression models of polarized information-chlorophyll content. The result indicated that when the polarized angle was 0 degrees, the model of chlorophyll content with polarization reflectance was built as Y = 4. 506 4e(-0.56 8x) (R2 = 0.895 8); while as the polarized angle was 90 degrees, the model of chlorophyll content with polarization reflectance was built as Y = 145.79X(-1.204 1)(R2 = 0.479 8); when the incidence angle was 50 degrees, the model of chlorophyll content with degree of polarization was built as Y = 7 206.7X(6) -20 160 X(5) + 22 547X(4)-12 788X(5) + 3 822.4X(2) -553.72X + 30.429 (R2 = 0.646 4). The authors found that a significant functional relationship between the polarized information and chlorophyll content exists. The study provides a theoretical base for vegetation remote sensing.

[Effects of multi-angle hyperspectral polarized reflection by forest soil].

In the present study, the authors measured samples of typical forest soils in different states with multi-angle hyperspectral polarized reflections. The authors analyzed multi-angle hyperspectral polarized reflections of soil data with various viewing zenith angles, incidence angles, relative azimuth angles, polarized states, soil water content and soil granule. The authors found that those factors affected the reflectance values of forest soils but not the spectral feature. The conclusions included that the larger the incidence angles and viewing zenith angles are, the bigger the polarized reflectance values of the surface of the forest soil. When the forest soil was dry, the surface had phenomenon of diffuse reflection and the polarized light reflection did not take place. When the soil moisture content reached a certain level, the polarized reflection appeared. The more the moisture content of the forest soil was, the smaller the polarized reflectance of the surface. The bigger the soil granule was and the rougher the soil surface was, the smaller the surface polarized reflectance. The results and conclusions suggested that the spectral characteristics of the ground target need to be considered adequately in order to design the best mode for sensor systems by remote sensing technology. The authors suggest that the incidence angle and viewing zenith angle be selected on the basis of factual instance. The authors suggest using larger viewing zenith angles and that the incidence angle should be equal to the viewing zenith angle. In the meantime, the effects of sheltering by ground targets need to be considered and the proper state of polarization should be chosen while keeping relative zenith angle at 180 degrees. This study not only helps find a new way for detection of soil characters, but also provides a theoretical basis for further research on multi-angle hyperspectral polarized reflection for detecting characteristic spectrum and best states in measuring forest soil.

[Effects of ligustrazine on extracellular acetylcholine levels in rat brain dialysate].

Using brain microdialysis and LC-MS/MS to detect acetylcholine in rat brain to investigate the effects of ligustrazine. A liquid chromatography-tandem mass spectrometry method has been developed and validated for the determination of acetylcholine in rat brain dialysate sampling by microdialysis. The results indicated that ligustrazine administration by subcutaneous injection significantly increased Ach release in rat medial prefrontal cortex and nucleus accumbens in a dose-related manner. The drug' s effect on Ach release in rat brain could be directly detected by microdialysis combined with HPLC-MS/MS and this method is selective and sensitive.