Information on forest structure is important for forest management decisions. This is inadequate in many situations, especially where timber is not of primary interest. We analyzed the structure of two forest types in...Information on forest structure is important for forest management decisions. This is inadequate in many situations, especially where timber is not of primary interest. We analyzed the structure of two forest types in the Oban Division of Cross River National Park, Nigeria. Systematic sampling technique was used to establish two transects measuring 2,000 x 2 m, at 600 m interval in the two forest types in four locations. Four 50 m x 50 m plots were located alternately at 500 m intervals along each transect, constituting 32 plots per forest type and 64 plots in all, Diameters at breast height （DBH）, base; middle and top; crown diameter; total height and crown length were measured on all trees with DBH 〉_ 10 cm. There were 159 stems/ha in the close-canopy forest and 132 stems/ha in the secondary forest. The mean DBH were 34.5 cm and 33.62 cm respectively. The mean heights were 24.79 m and 23.97 m, respectively. Basal area/ha were 41.59 m2 ha~ and 27.38 m2 hal for the two forest types. Majority of the trees encountered in the two forest types belonged to the middle stratum which has implication for small mammals＇ populations. Emergent trees which are otherwise scarce in other parts of the country were recorded, which also has implications for density thinning and seed supplies.展开更多
Abstract Conotoxins belong to the large families of disulfide-rich peptide toxins from cone snail venom, and can act on a broad spectrum of ion channels and receptors. They are classified into different subtypes based...Abstract Conotoxins belong to the large families of disulfide-rich peptide toxins from cone snail venom, and can act on a broad spectrum of ion channels and receptors. They are classified into different subtypes based on their targets. The a-conotoxins selectively inhibit the current of the nicotinic acetylcholine receptors. Because of their unique selectivity towards distinct nAChR subtypes, a-conotoxins become valuable tools in nAChR study. In addition to the X-ray structures of a-conotoxins in complex with acetyleholine-binding protein, a homolog of the nAChR ligand-binding domain, the high-resolution crystal structures of the extracellular domain of the al and a9 subunits are also obtained. Such structures not only revealed the details of the configuration of nAChR, but also provided higher sequence identity templates for modeling the binding modes of a-conotoxins to nAChR. This mini-review summarizes recent modeling studies for the determination of the binding modes of a-conotoxins to nAChR. As there are not crystal structures of the nAChR in complex with conotoxins, computational modeling in combination of mutagenesis data is expected to reveal the molecular recognition mechanisms that govern the interactions between a-conotoxins and nAChR at molecular level. An accurate determination of the binding modes of a-conotoxins on AChRs allows rational design of a-conotoxin analogues with improved potency or selectivity to nAChRs.展开更多
This research aims to validate a structural equation modeling （SEM） model for measuring warehouse performance using data from an international company in Australia （company G）. Moreover, a methodological triangula...This research aims to validate a structural equation modeling （SEM） model for measuring warehouse performance using data from an international company in Australia （company G）. Moreover, a methodological triangulation method was also adopted to test whether different methodological approaches produce convergent findings about warehouse performance measurement （WPM）. These three different methods are the SEM model, the multiple case research study, and validation of the SEM model using data from 80 companies in Thailand and a company in Australia. With the results from the triangulation method, it is obvious that the SEM model can be used to measure the performance of warehouses in Thailand and Australia. Since the SEM model consists only of significant indicators, it is more appropriate than company G＇s scorecard. Furthermore, the SEM model can overcome the limitations of traditional models by allowing companies to compare their performance over time.展开更多
This paper analyzes determinants and consequences of managerial ownership within ownership structures of the selected European and Asian transition countries. Focus of the analysis is the influence of the specific uni...This paper analyzes determinants and consequences of managerial ownership within ownership structures of the selected European and Asian transition countries. Focus of the analysis is the influence of the specific unification of ownership and control on corporate performance. Findings in the paper are based on research that produced empirical data for Croatia which is subsequently compared with evidence from other Asian and European transition countries facing the same issues. Consequently, transitional ownership structures, influenced by actual privatization process, like emergent corporate governance mechanisms, highly concentrated ownership and undeveloped markets for corporate control are also described. Research findings show that direct or indirect managerial ownership are important phenomena in transition countries, research has also shown that stable and concentrated managerial ownership have positive effects on firms＇ profitability in the observed transitional environments.展开更多
The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophi...The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.展开更多
The atypical PKC isoforms （ζ and t） play essential roles in regulating various cellular processes. Both the hetero-interaction between PKCζand p62 through their N-terminal PB 1 domains and the homo-oligomerization...The atypical PKC isoforms （ζ and t） play essential roles in regulating various cellular processes. Both the hetero-interaction between PKCζand p62 through their N-terminal PB 1 domains and the homo-oligomerization of p62 via its PB 1 domain are critical for the activation of NF-r.B signaling; however, the molecular mechanisms concerning the formation and regulation of these homotypic complexes remain unclear. Here we determined the crystal structure of PKCζ-PB 1 in complex with a mono- meric p62-PB 1 mutant, where the massive electrostatic interactions between the acidic OPCA motif of PKCζ-PB 1 and the basic surface of p62-PB 1, as well as additional hydrogen bonds, ensure the formation of a stable and specific complex. The PKCζ-p62 interaction is interfered with the modification of a specific Cys of PKCζ by the antiarthritis drug aurothiomalate, though all four cysteine residues in the PKCζ-PB 1 domain can be modified in in vitro assay. In addition, detailed structural and biochemical analyses demonstrate that the PB 1 domains of aPKCs belong to the type I group, which can depolymerize the high-molecular-weight p62 aggregates into homo-oligomers of lower order. These data together unravel the molecular mecha- nisms of the homo- or hetero-interactions between p62 and PKCζ and provide the basis for designing inhibitors of NF-r,.B sig- naling.展开更多
Non-structural protein 1 （NS1） of the influenza virus plays a crucial role in modulating the host immune response and facili- tating virus replication. The formation of a homodimer or an oligomer is necessary for NS...Non-structural protein 1 （NS1） of the influenza virus plays a crucial role in modulating the host immune response and facili- tating virus replication. The formation of a homodimer or an oligomer is necessary for NSI to exert its function efficiently. In the present study, the NS 1 protein from the A/Shantou/602/06（H3N2） virus （herein abbreviated as NS32） was found to interact with NS1 from A/Shantou/169/O6（H1N1）, A/Chicken/Guangdong/1/05（HSN1） and A/Quail/Hong Kong/G1/97（H9N2） （abbre- viated as NS11, NS51 and NS92, respectively） viruses, although NS32 shares 17.4%-20.9% sequence diversity with NS11, NS51 and NS92. This indicates that the heterologous interactions between NS1 proteins from different influenza A virus sub- types/strains may be a common event during co-infection.展开更多
文摘Information on forest structure is important for forest management decisions. This is inadequate in many situations, especially where timber is not of primary interest. We analyzed the structure of two forest types in the Oban Division of Cross River National Park, Nigeria. Systematic sampling technique was used to establish two transects measuring 2,000 x 2 m, at 600 m interval in the two forest types in four locations. Four 50 m x 50 m plots were located alternately at 500 m intervals along each transect, constituting 32 plots per forest type and 64 plots in all, Diameters at breast height （DBH）, base; middle and top; crown diameter; total height and crown length were measured on all trees with DBH 〉_ 10 cm. There were 159 stems/ha in the close-canopy forest and 132 stems/ha in the secondary forest. The mean DBH were 34.5 cm and 33.62 cm respectively. The mean heights were 24.79 m and 23.97 m, respectively. Basal area/ha were 41.59 m2 ha~ and 27.38 m2 hal for the two forest types. Majority of the trees encountered in the two forest types belonged to the middle stratum which has implication for small mammals＇ populations. Emergent trees which are otherwise scarce in other parts of the country were recorded, which also has implications for density thinning and seed supplies.
基金supported by the National Natural Science Foundation of China (81502977 to Dr. Yu R. and 81373322 to Dr. Jiang T.)China Postdoctoral Science Foundation funded project (No.861505020050 for Dr. Yu R.)+1 种基金Special Foundation for Qingdao Basic Research Program (15-9-1-85-jch)Fundamental Research Funds for the Central Universities (No.841512007 for Dr. Yu R.)
文摘Abstract Conotoxins belong to the large families of disulfide-rich peptide toxins from cone snail venom, and can act on a broad spectrum of ion channels and receptors. They are classified into different subtypes based on their targets. The a-conotoxins selectively inhibit the current of the nicotinic acetylcholine receptors. Because of their unique selectivity towards distinct nAChR subtypes, a-conotoxins become valuable tools in nAChR study. In addition to the X-ray structures of a-conotoxins in complex with acetyleholine-binding protein, a homolog of the nAChR ligand-binding domain, the high-resolution crystal structures of the extracellular domain of the al and a9 subunits are also obtained. Such structures not only revealed the details of the configuration of nAChR, but also provided higher sequence identity templates for modeling the binding modes of a-conotoxins to nAChR. This mini-review summarizes recent modeling studies for the determination of the binding modes of a-conotoxins to nAChR. As there are not crystal structures of the nAChR in complex with conotoxins, computational modeling in combination of mutagenesis data is expected to reveal the molecular recognition mechanisms that govern the interactions between a-conotoxins and nAChR at molecular level. An accurate determination of the binding modes of a-conotoxins on AChRs allows rational design of a-conotoxin analogues with improved potency or selectivity to nAChRs.
文摘This research aims to validate a structural equation modeling （SEM） model for measuring warehouse performance using data from an international company in Australia （company G）. Moreover, a methodological triangulation method was also adopted to test whether different methodological approaches produce convergent findings about warehouse performance measurement （WPM）. These three different methods are the SEM model, the multiple case research study, and validation of the SEM model using data from 80 companies in Thailand and a company in Australia. With the results from the triangulation method, it is obvious that the SEM model can be used to measure the performance of warehouses in Thailand and Australia. Since the SEM model consists only of significant indicators, it is more appropriate than company G＇s scorecard. Furthermore, the SEM model can overcome the limitations of traditional models by allowing companies to compare their performance over time.
文摘This paper analyzes determinants and consequences of managerial ownership within ownership structures of the selected European and Asian transition countries. Focus of the analysis is the influence of the specific unification of ownership and control on corporate performance. Findings in the paper are based on research that produced empirical data for Croatia which is subsequently compared with evidence from other Asian and European transition countries facing the same issues. Consequently, transitional ownership structures, influenced by actual privatization process, like emergent corporate governance mechanisms, highly concentrated ownership and undeveloped markets for corporate control are also described. Research findings show that direct or indirect managerial ownership are important phenomena in transition countries, research has also shown that stable and concentrated managerial ownership have positive effects on firms＇ profitability in the observed transitional environments.
基金Supported by the National Natural Science Foundation of China (31070042,30870039,30921065)partially by Open Funding Project of the National Key Laboratory of Biochemical Engineering,China (2010KF-2)
文摘The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.
基金supported in part by the National Natural Science Foundation of China(31070643 and 31130062)Tsinghua University(20121080028)
文摘The atypical PKC isoforms （ζ and t） play essential roles in regulating various cellular processes. Both the hetero-interaction between PKCζand p62 through their N-terminal PB 1 domains and the homo-oligomerization of p62 via its PB 1 domain are critical for the activation of NF-r.B signaling; however, the molecular mechanisms concerning the formation and regulation of these homotypic complexes remain unclear. Here we determined the crystal structure of PKCζ-PB 1 in complex with a mono- meric p62-PB 1 mutant, where the massive electrostatic interactions between the acidic OPCA motif of PKCζ-PB 1 and the basic surface of p62-PB 1, as well as additional hydrogen bonds, ensure the formation of a stable and specific complex. The PKCζ-p62 interaction is interfered with the modification of a specific Cys of PKCζ by the antiarthritis drug aurothiomalate, though all four cysteine residues in the PKCζ-PB 1 domain can be modified in in vitro assay. In addition, detailed structural and biochemical analyses demonstrate that the PB 1 domains of aPKCs belong to the type I group, which can depolymerize the high-molecular-weight p62 aggregates into homo-oligomers of lower order. These data together unravel the molecular mecha- nisms of the homo- or hetero-interactions between p62 and PKCζ and provide the basis for designing inhibitors of NF-r,.B sig- naling.
基金supported by the National Natural Science Foundation of China(Grant Nos.30972766,31170852,81001322,81172795,and 81072622)Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20094402110004)+1 种基金Scientific Research Foundation of Shantou University Medical College(Grant No.LC0401)211 Project of Guangdong Province(Mechanism and Prevention of Emerging Infectious Diseases)
文摘Non-structural protein 1 （NS1） of the influenza virus plays a crucial role in modulating the host immune response and facili- tating virus replication. The formation of a homodimer or an oligomer is necessary for NSI to exert its function efficiently. In the present study, the NS 1 protein from the A/Shantou/602/06（H3N2） virus （herein abbreviated as NS32） was found to interact with NS1 from A/Shantou/169/O6（H1N1）, A/Chicken/Guangdong/1/05（HSN1） and A/Quail/Hong Kong/G1/97（H9N2） （abbre- viated as NS11, NS51 and NS92, respectively） viruses, although NS32 shares 17.4%-20.9% sequence diversity with NS11, NS51 and NS92. This indicates that the heterologous interactions between NS1 proteins from different influenza A virus sub- types/strains may be a common event during co-infection.
