Simultaneous knockout of cytosolic and plastidial disproportionating enzymes disrupts grain setting and filling in rice.

Rice (Oryza sativa) plants contain plastidial and cytosolic disproportionating enzymes (DPE1 and DPE2). Our previous studies showed that DPE2 acts on maltose, the major product of starch degradation in pollens, releasing one glucose to fuel pollen tube growth and fertilization, whereas DPE1 participates in endosperm starch synthesis by transferring maltooligosyl groups from amylose to amylopectin, and removing excess short maltooligosaccharides. However, little is known about their integrated function. Here, we report that the coordinated actions of DPE1 and DPE2 contribute to grain setting and filling in rice. The dpe1dpe2 mutants could not be isolated from the progeny of heterozygous parental plants but were obtained via anther culture. Unlike that reported in Arabidopsis (Arabidopsis thaliana) and potato (Solanum tuberosum), the dpe1dpe2 rice plants grew normally but only yielded a small number of empty, unfilled seeds. In the dpe1dpe2 seeds, nutrient accumulation was substantially reduced, and dorsal vascular bundles were also severely malnourished. Zymogram analyses showed that changes in the activities of the major starch-synthesizing enzymes matched well with various endosperm phenotypes of mutant seeds. Mechanistically, DPE1 deficiency allowed normal starch mobilization in leaves and pollens but affected starch synthesis in endosperm, while DPE2 deficiency blocked starch degradation, resulting in substantially decreased levels of the sugars available for pollen tube growth and grain filling. Overall, our results demonstrate the great potential of DPE1-DPE2 as an important regulatory module to realize higher crop yields and present a promising target for regulating nutrient accumulation in cereal crop endosperm.

Cytosolic disproportionating enzyme2 is essential for pollen germination and pollen tube elongation in rice.

Degradation of starch accumulated in pollen provides energy and cellular materials for pollen germination and pollen tube elongation. Little is known about the function of cytosolic disproportionating enzyme2 (DPE2) in rice (Oryza sativa). Here, we obtained several DPE2 knockout mutant (dpe2) lines via genomic editing and found that the mutants grew and developed normally but with greatly reduced seed-setting rates. Reciprocal crosses between dpe2 and wild-type plants demonstrated that the mutant was male sterile. In vitro and in vivo examinations revealed that the pollen of the dpe2 mutant developed and matured normally but was defective in germination and elongation. DPE2 deficiency increased maltose content in pollen, whereas it reduced the levels of starch, glucose, fructose, and adenosine triphosphate (ATP). Exogenous supply of glucose or ATP to the germination medium partially rescued the pollen germination defects of dpe2. The expression of cytosolic phosphorylase2 (Pho2) increased significantly in dpe2 pollen. Knockout of Pho2 resulted in a semi-sterile phenotype. We failed to obtain homozygous dpe2 pho2 double mutant lines. Our results demonstrate that maltose catalyzed by DPE2 to glucose is the main energy source for pollen germination and pollen tube elongation, while Pho2 might partially compensate for deficiency of DPE2.

Reconstruction of Highly-Defective MgO and Exceptional Photochemical Activity on CO2 Upgrade in Aqueous Solution.

Defects on metal oxide have attracted extensive attention in photo-/electrocatalytic CO2 reduction. Herein, porous MgO nanosheets with abundant oxygen vacancies (Vo s) and three-coordinated oxygen atoms (O3c ) at corners are reported, which reconstruct into defective MgCO3 ·3H2 O exposing rich surface unsaturated -OH groups and vacancies to initiate photocatalytic CO2 reduction to CO and CH4 . In consecutive 7-cycle tests (each run for 6 h) in pure water, CO2 conversion keeps stable. The total production of CH4 and CO attains ≈367 µmol gcata -1 h-1 . The selectivity of CH4 gradually increases from ≈3.1% (1st run) to ≈24.5% (4th run) and then remains unchanged under UV-light irradiation. With triethanolamine (3.3 vol.%) as the sacrificial agent, the total production of CO and CH4 production rapidly increases to ≈28 000 µmol gcata -1 in 2 h reaction. Photoluminescence spectra reveal that Vo s induces the formation of donor bands to promote charge carrier seperation. A series of trace spectra and theoretical analysis indicate Mg-Vo sites in the derived MgCO3 ·3H2 O are active centers, which play a crucial role in modulating CO2 adsorption and triggering photoreduction reactions. These intriguing results on defective alkaline earth oxides as potential photocatalysts in CO2 conversion may spur some exciting and novel findings in this field.

Metallochaperone OsHIPP9 is involved in the retention of cadmium and copper in rice.

Metallochaperones are a unique class of proteins that play crucial roles in metal homoeostasis and detoxification. However, few metallochaperones have been functionally characterised in rice. Heterologous expression of Heavy metal-associated Isoprenylated Plant Protein 9 (OsHIPP9), a metallochaperone, altered yeast tolerance to cadmium (Cd) and copper (Cu). We investigated the physiological role of OsHIPP9 in rice. OsHIPP9 was primarily expressed in the root exodermis and xylem region of enlarged vascular bundles (EVB) at nodes. KO of OsHIPP9 increased the Cd concentrations of the upper nodes and panicle, but decreased Cd in expanded leaves. KO of OsHIPP9 decreased Cu uptake and accumulation in rice. Constitutive OX of OsHIPP9 increased Cd and Cu accumulation in aboveground tissues and brown rice. OsHIPP9 showed binding capacity for Cd and Cu. We propose that OsHIPP9 has dual metallochaperone roles, chelating Cd in the xylem region of EVB for Cd retention in the nodes and chelating Cu in rice roots to aid Cu uptake.

Pho1 cooperates with DPE1 to control short maltooligosaccharide mobilization during starch synthesis initiation in rice endosperm.

KEY MESSAGE: Plastidial α-glucan phosphorylase is a key factor that cooperates with plastidial disproportionating enzyme to control short maltooligosaccharide mobilization during the initiation process of starch molecule synthesis in developing rice endosperm. Storage starch synthesis is essential for grain filling. However, little is known about how cereal endosperm controls starch synthesis initiation. One of core events for starch synthesis initiation is short maltooligosaccharide (MOS) mobilization consisting of long MOS primer production and excess MOS breakdown. By mutant analyses and biochemical investigations, we present here functional identifications of plastidial α-glucan phosphorylase (Pho1) and disproportionating enzyme (DPE1) during starch synthesis initiation in rice (Oryza sativa) endosperm. Pho1 deficiency impaired MOS mobilization, triggering short MOS accumulation and starch synthesis reduction during early seed development. The mutant seeds differed significantly in MOS level and starch content at 15 days after flowering and exhibited diverse endosperm phenotypes during mid-late seed development: ranging from pseudonormal to shrunken (Shr), severely or excessively Shr. The level of DPE1 was almost normal in the PN seeds but significantly reduced in the Shr seeds. Overexpression of DPE1 in pho1 resulted in plump seeds only. DPE1 deficiency had no obvious effects on MOS mobilization. Knockout of DPE1 in pho1 completely blocked MOS mobilization, resulting in severely and excessively Shr seeds only. These findings show that Pho1 cooperates with DPE1 to control short MOS mobilization during starch synthesis initiation in rice endosperm.

Seroprevalence and risk factor analysis of Toxoplasma gondii infection in Siberian tigers (Panthera tigris altaica) and giant pandas (Ailuropoda melanoleuca) in China.

Toxoplasmosis, caused by Toxoplasma gondii, is a worldwide zoonosis. The aim of the present study was to detect the seroprevalence of T. gondii infection and associated risk factors among Siberian tigers (Panthera tigris altaica) and giant pandas (Ailuropoda melanoleuca) in China. Blood samples from 112 Siberian tigers and 22 giant pandas were tested for immunoglobulin G (IgG) against T. gondii by enzyme-linked immunosorbent assay (ELISA). The seroprevalence of T. gondii infection was 7.14% among Siberian tigers and 9.09% among giant pandas. No risk factors were found to be significantly associated with seroprevalence (P > 0.05). This is the first study to evaluate T. gondii infection in Siberian tigers on a large scale in China, and it also updates the information regarding the positivity rate of T. gondii infection among giant pandas in China.

OsFes1C, a potential nucleotide exchange factor for OsBiP1, is involved in the ER and salt stress responses.

The endoplasmic reticulum (ER) quality control system monitors protein homeostasis and relies on the activity of many molecular chaperones. Binding immunoglobulin protein (BiP) is a major ER luminal chaperone that is involved in most functions of the organelle. BiP activity is tightly regulated by nucleotide exchange factors (NEFs). However, information about NEFs in plants is limited. We obtained a Fes1-like protein (OsFes1C) through isobaric tags for relative and absolute quantitation-based proteomics analysis of ER-stressed rice (Oryza sativa) seeds. Unlike its homologs in yeast and mammals, which are located in the cytosol and respond to heat stress, OsFes1C is an ER membrane protein and responds to ER and salt stresses. OsFes1C interacts directly with OsBiP1 and the interaction is inhibited by ATP but promoted by ADP, suggesting that OsFes1C acts as a potential NEF of OsBiP1 in vivo. Overexpression or suppression of OsFes1C led to hypersensitivity to ER stress and affected the growth of rice. Furthermore, we established that OsFes1C directly interacts with a putative salt response protein and is involved in the salt response. Taken together, our study marks an important step toward elucidating the functional mechanisms of an identified ER stress response factor in rice.

First isolation of Trichuris from Chinese serow, Capricornis milneedwardsii (Cetartiodactyla: Caprinae).

Whipworms are soil-transmitted helminths that can infect a variety of animals. A Chinese serow possibly infected by whipworms was found during a wildlife disease surveillance project in Baima Snow Mountain National Nature Reserve, Yunnan, China, in 2021. As convergent evolution is common in coinhabiting parasites, a mitochondrial gene sequence (cox1) and ribosomal gene sequence (ITS1) were used to identify species similar to Trichuris from Chinese serow. The phylogenetic trees and genetic distances of ten Trichuris samples from a Chinese serow together with other Trichuris spp. that have been previously reported were analysed based on the cox1 and ITS1 sequences. The combined results of the phylogenetic tree and genetic distances based on cox1 gene showed that the whipworms in Chinese serow are T. skrjabini. However, the whipworms in the present study were divided into two apparent clades in the phylogenic trees constructed by the cox1 sequences (Clades A and B) and the ITS1 sequences (Clades C and D). In addition, the Fst and Nm values were 0.82 and 0.23 between Clade A and Clade B for the cox1 gene, and 0.30 and 0.45 between Clade C and Clade D for the ITS1 sequences; both indicators showed low gene flow among the clades. Therefore, the genetic population structure of T. skrjabini was illustrated.

The genetic characteristics of Sarcoptes scabiei from Chinese serow (Capricornis milneedwardsii) and goral (Naemorhedus goral arnouxianus) compared with other mites from different hosts and geographic locations using ITS2 and cox1 sequences.

Scabies is a common parasitic disease in many mammalian species, caused by the infestation of Sarcoptes scabiei. There is no consistent conclusion on whether Sarcoptes mites from different hosts or geographic locations have apparent genetic divergence. In this study, we collected and morphologically identified S. scabiei from Chinese serow and goral, and we described the genetic diversity of S. scabiei and other mites based on phylogenetic analyses of the ITS2 and cox1 sequence fragments, including data available in GenBank. The mites isolated from Chinese serow and goral were S. scabiei, and they were morphologically similar. The phylogenetic trees and haplotype networks showed that S. scabiei from other locations worldwide did not cluster according to host divergence or geographical distribution. Additionally, the Fst values were - 0.224 to 0.136 and - 0.045 to 1 between S. scabiei from different hosts, including humans and domestic and wild animals, based on partial ITS and cox1 sequences. Worldwide S. scabiei samples formed three clusters (with H2, H5, and H12 at their centers) in the ITS and one cluster (with C9 at the center) in the cox1 haplotype phylogenetic network. The S. scabiei collected from Chinese serow and goral were morphologically similar and had the same genotype. A study on the genetic characteristics of S. scabiei from Chinese serow and goral together with other mites from different hosts and geographic locations around the world showed no obvious divergence. These findings indicated that scabies likely is a zoonotic disease and that the global prevalence of scabies is probably related to the worldwide trade of domestic animals.

Study on Lgr5 expression in pancreas tissues and organoids by lineage tracing.

Leucine rich repeat containing G protein-coupled receptor 5(Lgr5) is widely expressed in multiple tissues and can be used as a stem cell marker in a variety of epithelial organs (including the small intestine, colon, stomach and hair follicles). In this study, we used Lgr5-CreERT2+/- and Rosa26-mTmG hybridized transgenic mice to investigate the expression of Lgr5 in both ductal epithelial cells during pancreas development and in vitro cultured pancreatic duct organoids. After induction with Tamoxifen, the Lgr5 expression was analyzed by detecting the enhanced green fluorescence protein in the pancreatic tissue sections in adult animals and embryos at different developmental stages. The results showed that Lgr5 expression was detected neither in adult pancreatic duct epithelia nor in the embryonic pancreatic tissues at day 15.5 or in newborn mice. However, when 4-hydroxy-Tamoxifen was supplemented to the culture medium, EGFP could be detected in the primary pancreatic duct organoids from Lgr5-Cre ERT2+/-; Rosa26-mTmG mice. These results suggested that Lgr5 was not expressed in adult and embryonic pancreatic tissues; but could be expressed in the cultured pancreas ductal organoids. The research lays the foundation for exploring specific gene expression patterns in stem/progenitor cells during pancreatic development.

Ixazomib inhibits myeloma cell proliferation by targeting UBE2K.

PURPOSE: Ixazomib is a selective, effective, and reversible inhibitor of 20S proteasome and is approved for the treatment of multiple myeloma. Ubiquitin-conjugating enzyme E2 (UBE2K) is involved in the synthesis of K48-linked ubiquitin chains and is the target of certain drugs used for the treatment of tumors. The purpose of this study was to investigate the relationship between ixazomib and UBE2K in myeloma cells. METHODS: We used CCK-8 and Annexin V-FITC/propidium iodide kit to detect the effects of ixazomib on survival and apoptosis of RPMI-8226 and U-266 myeloma cell lines. Quantitative polymerase chain reaction and western blot were used to detect the change in gene and protein expression levels of myeloma cells treated with ixazomib. Furthermore, the regulatory effects of ixazomib on UBE2K and its downstream targets were investigated following the overexpression of UBE2K. RESULTS: In myeloma cells, ixazomib decreased cell survival and increased apoptosis in a dose-dependent manner. Ixazomib significantly increased the expression of HIST1H2BD, MNAT1, NEK3, and TARS2, while decreasing the expression of HSPA1B and UBE2K. In addition, ixazomib inhibited the proliferation of myeloma cells, blocked cell cycle, induced cell apoptosis, and increased the production of reactive oxygen species by inhibiting UBE2K expression. Lastly, ixazomib regulates mitosis- and apoptosis-related genes by lowering UBE2K expression. CONCLUSION: In summary, ixazomib leads to impaired proliferation of myeloma cells by targeting UBE2K.

Declined expressing mRNA of beta-defensin 108 from epididymis is associated with decreased sperm motility in blue fox (Vulpes lagopus).

BACKGROUND: Fecundity is important for farm blue fox (Vulpes lagopus), who with asthenospermia have be a problem in some of farms in China. A key symptom of asthenospermia is decreased sperm motility. The decreased secreting beta-defensin108 (vBD108) of blue fox is speculated be related to asthenospermia. To clarify this idea, the mRNA expression of vBD108 in testis and epididymis of blue foxes with asthenospermia were detected and compared to the healthy one. The antibody was prepared and analyzed by immunohistochemistry. RESULTS: The vBD108 in testis and epididymis was found both in blue fox with asthenospermia and healthy group by the method of immunohistochemistry. The expression of vBD108 mRNA in testes (P < 0.05) and epididymal corpus (P < 0.0001) in asthenospermia group was lower than that in healthy group. CONCLUSIONS: These results suggested that vBD108 deficiency may related to blue fox asthenospermia. Meanwhile, the study on the blue fox vBD108 provides a hopeful direction to explore the pathogenesis of blue fox asthenospermia in the future.

Cytochrome P450 family member CYP96B5 hydroxylates alkanes to primary alcohols and is involved in rice leaf cuticular wax synthesis.

Odd-numbered primary alcohols are components of plant cuticular wax, but their biosynthesis remains unknown. We isolated a rice wax crystal-sparse leaf 5 (WSL5) gene using a map-based cloning strategy. The function of WSL5 was illustrated by overexpression and knockout in rice, heterologous expression in Arabidopsis and transient expression in tobacco leaves. WSL5 is predicted to encode a cytochrome P450 family member CYP96B5. The wsl5 mutant lacked crystalloid platelets on the surface of cuticle membrane, and its cuticle membrane was thicker than that of the wild-type. The wsl5 mutant is more tolerant to drought stress. The load of C23 -C33 alkanes increased, whereas the C29 primary alcohol reduced significantly in wsl5 mutant and WSL5 knockout transgenic plants. Overexpression of WSL5 increased the C29 primary alcohol and decreased alkanes in rice leaves. Heterologous expression of WSL5 increased the C29 primary alcohol and decreased alkanes, secondary alcohol, and ketone in Arabidopsis stem wax. Transient expression of WSL5 in tobacco leaves also increased the production C29 primary alcohol. WSL5 catalyzes the terminal hydroxylation of alkanes, yielding odd-numbered primary alcohols, and is involved in the formation of epidermal wax crystals on rice leaf, affecting drought sensitivity.

OsDER1 Is an ER-Associated Protein Degradation Factor That Responds to ER Stress.

Endoplasmic reticulum-associated protein degradation (ERAD) plays an important role in endoplasmic reticulum (ER) quality control. To date, little is known about the retrotranslocation machinery in the plant ERAD pathway. We obtained a DERLIN-like protein (OsDER1) through a SWATH-based quantitative proteomic analysis of ER membrane proteins extracted from ER-stressed rice (Oryza sativa) seeds. OsDER1, a homolog of yeast and mammal DER1, is localized in the ER and accumulates significantly under ER stress. Overexpression or suppression of OsDER1 in rice leads to activation of the unfolded protein response and hypersensitivity to ER stress, and suppression results in floury, shrunken seeds. In addition, the expression levels of polyubiquitinated proteins increased markedly in OsDER1 overexpression or suppression transgenic rice. Coimmunoprecipitation experiments demonstrated that OsDER1 interacted with OsHRD1, OsHRD3, and OsCDC48, the essential components of the canonical ERAD pathway. Furthermore, OsDER1 associated with the signal peptide peptidase, a homolog of a component of the alternative ERAD pathway identified recently in yeast and mammals. Our data suggest that OsDER1 is linked to the ERAD pathway.

Synthesis of C-C Bonded Two-Dimensional Conjugated Covalent Organic Framework Films by Suzuki Polymerization on a Liquid-Liquid Interface.

Synthesis of free-standing two-dimensional (2D) conjugated covalent organic framework (COF) films linked by C-C bonds is highly desirable. Now a very simple and mild strategy has been developed to synthesize them by Suzuki polymerization on a water-toluene interface in a refrigerator. The versatility of this strategy was confirmed by the successful synthesis of two different 2D-COF films: a porous graphene and a porphyrin-contained 2D-COF. Both 2D-COF films have large lateral size and their crystalline domains were visualized by high resolution TEM. Based on the wide compatibility of Suzuki reaction, our breakthrough work opened a door for the synthesis of various 2D conjugated COF films. For application studies, the porous graphene exhibits a good carrier mobility, which is much higher than -C=N- linked 2D COF films and a good catalytic activity for hydrogen evolution reaction, which is comparable with nitrogen- or phosphorus-doped graphene.

A ß-Ketoacyl-CoA Synthase Is Involved in Rice Leaf Cuticular Wax Synthesis and Requires a CER2-LIKE Protein as a Cofactor.

Cuticular waxes are complex mixtures of very-long-chain fatty acids (VLCFAs) and their derivatives, forming a natural barrier on aerial surfaces of terrestrial plants against biotic and abiotic stresses. In VLCFA biosynthesis, ß-ketoacyl-CoA synthase (KCS) is the key enzyme, catalyzing the first reaction in fatty acid elongation and determining substrate specificity. We isolated a rice (Oryza sativa) wax crystal-sparse leaf 4 (WSL4) gene using a map-based cloning strategy. WSL4 is predicted to encode a KCS, a homolog of Arabidopsis (Arabidopsis thaliana) CER6. Complementation of the mutant wsl4-1 with WSL4 genomic DNA rescued the cuticular wax-deficient phenotype, confirming the function of WSL4 The load of wax components longer than 30 carbons (C30) and C28 were reduced markedly in wsl4-1 and wsl4-2 mutants, respectively. Overexpression of WSL4 increased the cuticular wax load in rice leaves. We further isolated a cofactor of WSL4, OsCER2, a homolog of Arabidopsis CER2, by coimmunoprecipitation and confirmed their physical interaction by split-ubiquitin yeast two-hybrid experiments. Expression of WSL4 alone in elo3 yeast cells resulted in increased C24 but did not produce VLCFAs of greater length, whereas expressing OsCER2 alone showed no effect. Coexpression of WSL4 and OsCER2 in elo3 yeast cells yielded fatty acids up to C30. OsCER2 with a mutated HxxxD motif (H172E, D176A, and D176H) interrupted its interaction with WSL4 and failed to elongate VLCFAs past C24 when expressed with WSL4 in elo3 yeast cells. These results demonstrated that WSL4 was involved in VLCFA elongation beyond C22 and that elongation beyond C24 required the participation of OsCER2.

A conserved motif is essential for the correct assembly of proglutelins and for their export from the endoplasmic reticulum in rice endosperm.

Rice glutelins are initially synthesized as 57-kDa precursors at the endoplasmic reticulum (ER) and are ultimately transported into protein storage vacuoles. However, the sequence motifs that affect proglutelin folding, assembly, and their export from the ER remain poorly defined. In this study, we characterized a mutant with nine amino acids deleted in the GluA2 protein, which resulted in specific accumulation of the GluA precursor. The deleted amino acids constitute a well-conserved sequence (LVYIIQGRG) in glutelins and all residues in this motif are necessary for ER export of GluA2. Immunoelectron microscopy and stable transgenic analyses indicated that proglutelins with deletion of this motif misassembled and aggregated through non-native intermolecular disulfide bonds, and were deposited in ER-derived protein bodies (PB-Is), resulting in conversion of PB-Is into a new type of PB. These results indicate that the conserved motif is essential for proper assembly of proglutelin. The correct assembly of proglutelins is critical for their segregation from prolamins in the ER lumen, which is essential for enabling the export of proglutelin from the ER and for the proper formation of PB-Is. We also found that the interchain disulfide bond between acidic and basic subunits is not necessary for their assembly, but it is required for proglutelin folding.

A Novel Green TiO2 Photocatalyst with a Surface Charge-Transfer Complex of Ti and Hydrazine Groups.

The optical property of TiO2 plays an important role in its various and promising photocatalytic applications. Previous efforts in improving its optical properties include doping with various metal and/or non-metal elements, coupling with other colorful semiconductors or molecules, and hydrogenating to crystalline/disordered core/shell nanostructures. Here, we report a beautiful green TiO2 achieved by forming the charge-transfer complex of colorless hydrazine groups and surface Ti4+ , which extends the optical absorption into the near infrared region (≈1100 nm, 1.05 eV). It shows an enhanced photocatalytic performance in hydrogen generation under simulated sunlight, and degradation of organic pollution under visible light due to an impurity state (about 0.28 eV) resulting in fast electron-hole separation and injection of electrons from the ligand to the conduction band of TiO2 . This study demonstrates an alternative approach to tune the optical, impurity state and photocatalytic properties of TiO2 nanoparticles and we believe this will spur a wide interest in related materials and applications.

Plastidial Disproportionating Enzyme Participates in Starch Synthesis in Rice Endosperm by Transferring Maltooligosyl Groups from Amylose and Amylopectin to Amylopectin.

Plastidial disproportionating enzyme1 (DPE1), an α-1,4-d-glucanotransferase, has been thought to be involved in storage starch synthesis in cereal crops. However, the precise function of DPE1 remains to be established. We present here the functional identification of DPE1 in storage starch synthesis in rice (Oryza sativa) by endosperm-specific gene overexpression and suppression. DPE1 overexpression decreased amylose content and resulted in small and tightly packed starch granules, whereas DPE1 suppression increased amylose content and formed heterogeneous-sized, spherical, and loosely packed starch granules. Chains with degree of polymerization (DP) of 6 to 10 and 23 to 38 were increased, while chains with DP of 11 to 22 were decreased in amylopectin from DPE1-overexpressing seeds. By contrast, chains with DP of 6 to 8 and 16 to 36 were decreased, while chains with DP of 9 to 15 were increased in amylopectin from DPE1-suppressed seeds. Changes in DPE1 gene expression also resulted in modifications in the thermal and pasting features of endosperm starch granules. In vitro analyses revealed that recombinant DPE1 can break down amylose into maltooligosaccharides in the presence of Glc, while it can transfer maltooligosyl groups from maltooligosaccharide to amylopectin or transfer maltooligosyl groups within and among amylopectin molecules in the absence of Glc. Moreover, a metabolic flow of maltooligosyl groups from amylose to amylopectin was clearly identifiable when comparing DPE1-overexpressing lines with DPE1-suppressed lines. These findings demonstrate that DPE1 participates substantially in starch synthesis in rice endosperm by transferring maltooligosyl groups from amylose and amylopectin to amylopectin.

Three-Dimensional Crystalline/Amorphous Co/Co3O4 Core/Shell Nanosheets as Efficient Electrocatalysts for the Hydrogen Evolution Reaction.

Earth-abundant, low-cost electrocatalysts with outstanding catalytic activity in the electrochemical hydrogen evolution reaction (HER) are critical in realizing the hydrogen economy to lift our future welfare and civilization. Here we report that excellent HER activity has been achieved with three-dimensional core/shell Co/Co3O4 nanosheets composed of a metallic cobalt core and an amorphous cobalt oxide shell. A benchmark HER current density of 10 mA cm(-2) has been achieved at an overpotential of ∼90 mV in 1 M KOH. The excellent activity is enabled with the unique metal/oxide core/shell structure, which allows high electrical conductivity in the core and high catalytic activity on the shell. This finding may open a door to the design and fabrication of earth-abundant, low-cost metal oxide electrocatalysts with satisfactory hydrogen evolution reaction activities.