Effects of landscape and management on ground‐dwelling insect assemblages of farmland in Jeju Island,Korea

Granite‐derived soils are widespread in the farmland of Korea in general. In contrast, Jeju Island has mainly volcanic ash soils. Soils and weather condition in Jeju Island created a unique agricultural system. We identified the features of ground‐dwelling insects in farmlands of Jeju Island. This study was conducted in four areas (Samdal‐ri and Susan‐ri in Seogwipo city, and Dongmyeong‐ri and Suwon‐ri in Jeju city) in Jeju Island, Korea. Field surveys were carried out twice in summer (June) and autumn (September) in 2013. Ground‐dwelling insects were sampled quantitatively by using pitfall traps. As a result, in total 3322 individuals, 137 species, 48 families and 8 orders were investigated in farmlands of Jeju Island. Especially, members of Coleoptera and Hymenoptera accounted for a large proportion of ground‐dwelling insect communities. The numbers of species and individuals for major taxonomic groups showed significant regional and seasonal differences. This study implied that the seasonal and regional differences of ground‐dwelling insect communities were affected by surrounding land use patterns, life history patterns of each taxonomic group and farmland management.     

Stereoselective synthesis of 1'-functionalized-4'-thionucleosides

Stereoselective functionalization of the 1'-position of 4'-thionucleosides was achieved using a stereoselective S(N)2 reaction controlled by 5-membered ring coordination.     

Polyethyleneimine-mediated chemical extraction of cytoplasmic His-tagged inclusion body proteins from Escherichia coli

The selectivity of polyethyleneimine (PEI) in DNA precipitation during chemical extraction was investigated. Chemical extraction was used to recover two His-tagged model proteins: gloshedobin, a thrombin-like enzyme from snake venom, and IbpA, a molecular chaperone, which were expressed mainly in the form of inclusion bodies. High DNA removal efficiency (more than 90%) was achieved at various cell densities (with OD600 ranging from 30 to 150) without affecting the solubility of host cell proteins. Compared to spermine-induced precipitation method reported elsewhere, PEI provided a higher DNA precipitation efficiency at a significantly lower cost. Moreover, PEI obviated the use of EDTA, which has been reported to be essential for the chemical extraction methods, hence exhibiting dual roles in replacing cost-prohibitive spermine and EDTA. The residual PEI in the post-extraction mixture was efficiently counteracted by addition of Mg2+, allowing the streamlined application of the extraction broth to immobilized metal affinity chromatography. Taken together, the PEI-mediated chemical extraction method provides a simpler and more economically viable processing route for the production of recombinant proteins whose expression is hampered by IB formation.     

XPC promotes MDM2-mediated degradation of the p53 tumor suppressor

Although ubiquitin receptor Rad23 has been implicated in bringing ubiquitylated p53 to the proteasome, how Rad23 recognizes p53 remains unclear. We demonstrate that XPC, a Rad23-binding protein, regulates p53 turnover. p53 protein in XPC-deficient cells remains ubiquitylated, but its association with the proteasome is drastically reduced, indicating that XPC regulates a postubiquitylation event. Furthermore, we found that XPC participates in the MDM2-mediated p53 degradation pathway via direct interaction with MDM2. XPC W690S pathogenic mutant is specifically defective for MDM2 binding and p53 degradation. p53 is known to become stabilized following UV irradiation but can be rendered unstable by XPC overexpression, underscoring a critical role of XPC in p53 regulation. Elucidation of the proteolytic role of XPC in cancer cells will help to unravel the detailed mechanisms underlying the coordination of DNA repair and proteolysis.     

Enhancement of erythropoietin production in recombinant Chinese hamster ovary cells by sodium lactate addition

The stabilization of optimum pH for cells can cause a higher erythropoietin (EPO) production rate and a good growth rate with the prolonged culture span in recombinant Chinese hamster ovary (r-CHO) cells. Our strategy for stabilizing the optimum pH in this study is to reduce the lactate production by adding sodium lactate to a culture medium. When 40 mM sodium lactate was added, a specific growth rate was decreased by approximately 22% as compared with the control culture. However the culture longevity was extended to 187 h, and more than a 2.7-fold increase in a final accumulated EPO concentration was obtained at 40 mM of sodium lactate. On the condition that caused the high production of EPO, a specific glucose consumption rate and lactate production rate decreased by 23.3 and 52%, respectively. Activity of lactate dehydrogenase (LDH) in r-CHO cells increased and catalyzed the oxidation of lactate to pyruvate, together with the reverse reaction, at the addition of 40 mM sodium lactate. The addition of 40 mM sodium lactate caused the positive effects on a cell growth and an EPO production in the absence of carbon dioxide gas as well as in the presence of carbon dioxide gas by reducing the accumulation of lactate.     

Impacts of Intergroup Interactions on Intragroup Behavioral Changes in Javan Gibbons (Hylobates moloch)

International Journal of Primatology - Agonistic intergroup interactions can cause individual costs such as physical injuries, increased physiological stress, and disrupted intragroup social...     

Leishmania mexicana glycerol-3-phosphate dehydrogenase showed conformational changes upon binding a bi-substrate adduct

Certain pathogenic trypanosomatids are highly dependent on glycolysis for ATP production, and hence their glycolytic enzymes, including glycerol-3-phosphate dehydrogenase (GPDH), are considered attractive drug targets. The ternary complex structure of Leishmania mexicana GPDH (LmGPDH) with dihydroxyacetone phosphate (DHAP) and NAD(+) was determined to 1.9A resolution as a further step towards understanding this enzyme's mode of action. When compared with the apo and binary complex structures, the ternary complex structure shows an 11 degrees hinge-bending motion of the C-terminal domain with respect to the N-terminal domain. In addition, residues in the C-terminal domain involved in catalysis or substrates binding show significant movements and a previously invisible five-residue loop region becomes well ordered and participates in NAD(+) binding. Unexpectedly, DHAP and NAD(+) appear to form a covalent bond, producing an adduct in the active site of LmGPDH. Modeling a ternary complex glycerol 3-phosphate (G3P) and NAD(+) with LmGPDH identified ten active site residues that are highly conserved among all GPDHs. Two lysine residues, Lys125 and Lys210, that are presumed to be critical in catalysis, were mutated resulting in greatly reduced catalytic activity. Comparison with other structurally related enzymes found by the program DALI suggested Lys210 as a key catalytic residue, which is located on a structurally conserved alpha-helix. From the results of site-directed mutagenesis, molecular modeling and comparison with related dehydrogenases, a catalytic mechanism of LmGPDH and a possible evolutionary scenario of this group of dehydrogenases are proposed.