森林生态系统服务功能及其生态经济价值评估初探——以海南岛尖峰岭热带森林为例

以尖峰岭地区为研究区域,探讨了森林生态系统服务功能的内涵,并使用市场价值、影子工程、机会成本和替代花费等方法评价了海南岛尖峰岭地区热带森林生态系统服务功能的生态经济价值.结果表明,在尖峰岭地区,面积为44667.00hm²的热带森林生态系统服务功能价值平均每年66438.49万元,其中林产品价值为7164.11万元,涵养水源价值为39429.21万元,保持土壤减少侵蚀价值为247.26万元,固定CO₂减轻温室效应的价值为1316.24万元,营养物循环价值为428.55万元,净化空气的价值为17853.12万元.     

Anticomplementary Activity of Antitumour Polysaccharides

THE polysaccharides obtained from some basidiomycetes, Pleurotus ostreatus (Jacq. ex Fr.) Quel.¹, Flammulina velutipes (Curt, ex Fr.) Sing.², Lentinus edodes (Berk.) Sing.^2–4, Polia cocos, Wolf (Bukuryo)⁵ and Schizophyllum commune Fr.⁷, strongly inhibit the growth of sarcoma 180 and their anti-tumour activity is host-mediated^8,9.     

Interplay between recombinant Hsp70 and proteasomes: proteasome activity modulation and ubiquitin-independent cleavage of Hsp70

The heat shock protein 70 (Hsp70, human HSPA1A) plays indispensable roles in cellular stress responses and protein quality control (PQC). In the framework of PQC, it cooperates with the ubiquitin-proteasome system (UPS) to clear damaged and dysfunctional proteins in the cell. Moreover, Hsp70 itself is rapidly degraded following the recovery from stress. It was demonstrated that its fast turnover is mediated via ubiquitination and subsequent degradation by the 26S proteasome. At the same time, the effect of Hsp70 on the functional state of proteasomes has been insufficiently investigated. Here, we characterized the direct effect of recombinant Hsp70 on the activity of 20S and 26S proteasomes and studied Hsp70 degradation by the 20S proteasome in vitro. We have shown that the activity of purified 20S proteasomes is decreased following incubation with recombinant human Hsp70. On the other hand, high concentrations of Hsp70 activated 26S proteasomes. Finally, we obtained evidence that in addition to previously reported ubiquitin-dependent degradation, Hsp70 could be cleaved independent of ubiquitination by the 20S proteasome. The results obtained reveal novel aspects of the interplay between Hsp70 and proteasomes.     

Requirement of translocated lysosomal V1 H(+)-ATPase for activation of membrane acid sphingomyelinase and raft clustering in coronary endothelial cells

Acid sphingomyelinase (ASM) mediates the formation of membrane raft (MR) redox signalosomes in a process that depends on a local acid microenvironment in coronary arterial endothelial cells (CAECs). However, it is not known how this local acid microenvironment is formed and maintained. The present study hypothesized that lysosomal V1 H(+)-ATPase provides a hospitable acid microenvironment for activation of ASM when lysosomes traffic and fuse into the cell membrane. Confocal microscopy showed that local pH change significantly affected MRs, with more fluorescent patches under low pH. Correspondingly, the ASM product, ceramide, increased locally in the cell membrane. Electron spin resonance assay showed that local pH increase significantly inhibited NADPH oxidase-mediated production of O(2)(-.) in CAECs. Direct confocal microscopy demonstrated that Fas ligand resulted in localized areas of decreased pH around CAEC membranes. The inhibitors of both lysosomal fusion and H(+)-ATPase apparently attenuated FasL-caused pH decrease. V1 H(+)-ATPase accumulation and activity on cell membranes were substantially suppressed by the inhibitors of lysosomal fusion or H(+)-ATPase. These results provide the first direct evidence that translocated lysosomal V1 H(+)-ATPase critically contributes to the formation of local acid microenvironment to facilitate activation of ASM and consequent MR aggregation, forming MR redox signalosomes and mediating redox signaling in CAECs.     

Apoptosis in fresh and cryopreserved cardiac valves of pig samples

To analyse the influence of cold ischemic time (CIT) (2–24 h) and of cryopreservation (liquid phase) on the viability of the valvular fibroblasts and in the presence of apoptosis. Cardiac valves from 10 pigs were evaluated by anatomo-pathological study of the wall, muscle and leaflet. At the same time, the presence of cellular death due to apoptosis was investigated in two ways; directly on tissue by Apodetec system and by two-colour flow cytometry assay analyzing a suspension of fibroblast from valve leaflets using Anexina V and propidium iodure (PI). We established three groups of samples to compare different experimental conditions: 2 h of ischemia (group 1), 24 h of ischemia (group 2), and a programme of cryopreservation (−1°C/min) after 2 h of ischemia, followed by storage in liquid nitrogen during a week and thawing was performed (group 3). The analysis of viabilities showed slight differences between all three groups. The results indicated CIT of 24 h undergoing more structural affectation than CIT of 2 h. Flow cytometry analysis did not show important differences between groups; however cryopreserved samples (group 3) slightly less viability and a higher percentage of death by apoptosis than group 1 and 2 using flow cytometry. Apoptosis was confirmed on tissue from all valves but mainly in samples of group 2 and group 3. In summary, the viability of the valves in the case of ischemic times of 2 h, 24 h or after cryopreservation/thawing differs slightly. The death of the cells is mainly mediated by necrosis and not by apoptosis.     

Calcium spikes in a leech nonspiking neuron

The NS neurons are nonspiking cells, present as pairs in each midbody ganglion of the leech nervous system, which display a very extensive arborization. They were shown to regulate the coactivation of motoneurons. Here we have investigated the electrophysiological properties of these neurons under the hypothesis that transmission along the extensive neurites requires the aid of voltage-dependent conductances. The results indicate that NS neurons respond to electrical stimulation with a spike-like event, which was not an all-or-none but rather a graded phenomenon that depended on the intensity and duration of the electrical stimulus. The spike-like response was activated at a membrane potential of approximately −50 mV; its amplitude was a logarithmic function of the extracellular Ca²⁺ concentration and was unaffected by a broad range of changes in the extracellular Na⁺ concentration; intracellular application of tetraethylammonium (TEA) caused a large increase in its amplitude and duration. These data indicate that NS neurons bear voltage-dependent low-threshold Ca²⁺ and TEA-sensitive K⁺ conductances that could contribute to shaping synaptic signals, or transmission along the extensive neuritic tree.     

Toward Long‐Term Stable and Highly Efficient Perovskite Solar Cells via Effective Charge Transporting Materials

Perovskite solar cells (PSCs) have advanced quickly with their power conversion efficiency approaching the record of silicon solar cells. However, there is still a big challenge to obtain both high efficiency and long‐term stability for future commercialization of PSCs. The major instability issue is associated with the decomposition or phase transition of perovskite materials that are believed to be intrinsically unstable under outdoor working conditions. Herein, the authors review the approaches that marked important progress in developing new functional electron/hole transporting materials that enabled highly efficient and stable PSCs. The findings that accelerate charge diffusion and that suppress the irrevocable loss of ions diffusing out of perovskite materials and other diffusion processes are highlighted. In addition, derivative interface engineering methods to control the diffusion process of charges/ions/molecules are also reviewed. Finally, the authors propose key research issues in charge transporting materials and interface engineering with regard to the important diffusion processes that will be one of the keys to realize highly efficient and long‐term stable PSCs.     

Overlapping motifs (PTAP and PPEY) within the Ebola virus VP40 protein function independently as late budding domains: involvement of host proteins TSG101 and VPS-4

The VP40 protein of Ebola virus can bud from mammalian cells in the form of lipid-bound, virus-like particles (VLPs), and late budding domains (L-domains) are conserved motifs (PTAP, PPxY, or YxxL; where "x" is any amino acid) that facilitate the budding of VP40-containing VLPs. VP40 is unique in that potential overlapping L-domains with the sequences PTAP and PPEY are present at amino acids 7 to 13 of VP40 (PTAPPEY). L-domains are thought to function by interacting with specific cellular proteins, such as the ubiquitin ligase Nedd4, and a component of the vacuolar protein sorting (vps) pathway, tsg101. Mutational analysis of the PTAPPEY sequence of VP40 was performed to understand further the contribution of each individual motif in promoting VP40 budding. In addition, the contribution of tsg101 and a second member of the vps pathway, vps4, in facilitating budding was addressed. Our results indicate that (i) both the PTAP and PPEY motifs contribute to efficient budding of VP40-containing VLPs; (ii) PTAP and PPEY can function as L-domains when separated and moved from the N terminus (amino acid position 7) to the C terminus (amino acid position 316) of full-length VP40; (iii) A VP40-PTAP/tsg101 interaction recruits tsg101 into budding VLPs; (iv) a VP40-PTAP/tsg101 interaction recruits VP40 into lipid raft microdomains; and (v) a dominant-negative mutant of vps4 (E228Q), but not wild-type vps4, significantly inhibited the budding of Ebola virus (Zaire). These results provide important insights into the complex interplay between viral and host proteins during the late stages of Ebola virus budding.