评述细根指标测定的几种方法

细根(直径≤2 mm)是树木吸收养分和水分的主要器官,其生产和周转构成了森林生态系统物质循环和能量流动的主体。由于细根的测定方法不同会导致细根生物量、生产、周转和寿命等指标的差异。同时,细根的测定方法均有一定的局限性和缺陷。因此,细根的测定方法已经成为目前细根生态学领域的热点问题之一。近年来细根的研究方法主要以根钻法、内生长法、微根管法和土壤碳通量法为主。文章就这几种常用方法对细根生物量、生产、周转、寿命等指标的研究方法进行评述。

中国16个地点天然次生林细根产量分布格局

细根产量(FRP)是森林生态系统地下产量的最大组分,对森林生态系统的碳和养分的分配和循环起着重要作用。细根根序对于FRP有较大的影响。目前较少通过根序分级法、以我国16个地点的天然次生林为整体的大尺度FRP研究。采用根序分级法对我国16个地点的天然次生林进行为期1年的、群落水平的大尺度FRP实验研究,来探索我国16个地点的天然次生林FRP分布格局。结果表明,FRP分布格局总体上由北向南逐渐增加,吸收根(AFR)产量、运输根(TFR)产量以及FRP均为海南尖峰岭最高,分别为(115.42±17.87)g/m^(2)、(298.6±76.82)g/m^(2)和(414.01±84.05)g/m^(2),大兴安岭呼中区最低,分别为(11.25±1.28)g/m^(2)、(12.44±0.97)g/m^(2)和(23.7±1.21)g/m^(2)。山西太岳山、安徽鹞落坪和湖南会同显著低于邻近纬度地区(P<0.05),FRP分别为(50.89±5.58)g/m^(2)、(58.85±17.24)g/m^(2)和(67.26±15.31)g/m^(2)。年均温(MAT)和年均降水量(MAP)与AFR产量、TFR产量和FRP显著正相关,纬度与AFR产量、TFR产量和FRP显著负相关。

高寒草甸植被细根生产和周转的比较研究

植物根系是陆地生态系统重要的碳汇和养分库,细根周转过程是陆地生态系统地下部分碳氮循环的核心环节,在陆地生态系统如何响应全球变化中起着关键作用。在全球变化敏感地区之一的青藏高原,对该地区的主要植被类型矮嵩草草甸同时采用根钻法、内生长袋法和微根管法3种观测方法研究细根生产和周转速率,并探讨了极差法、积分法、矩阵法和Kaplan-Meier法等数据处理方法对计算值的影响。研究结果显示:在估算细根净初级生产力时,根钻法宜采用积分法,内生长袋法宜选用矩阵法;由此进一步以最大细根生物量为基础,根钻法和内生长袋法估测的细根年周转速率分别为0.36 a-1和0.52 a-1,内生长袋法的估算结果是根钻法的1.44倍。对于微根管法,将其观测得到的细根长度转换为单位面积的生物量值后,采用积分法计算出细根周转速率为0.84 a-1,远高于传统方法的估算结果;若采用Kaplan-Meier生存分析方法,则计算出的细根周转速率更高达3.41 a-1。

Enhanced plasma ghrelin levels in Helicobacter py/ori-colonized, interleukin-1-receptortype 1-homozygous knockout (IL-1R1-/-) mice

AIM： Ghrelin is an endogenous ligand for the growth hormone secretagogue receptor, and it plays a role in stimulating the growth hormone secretion, food intake,body weight gain and gastric motility. Eradication of Helicobacterpylori （H pylon） was shown to be associated with increase of the body weight. On the other hand, Hpylori infection evokes the release of gastric IL-1β. The present study was designed to investigate the involvement of the gastric IL-1 signal in the ghrelin dynamics in Hpyloricolonized mice.METHODS： Twelve-week-old female IL-l-receptor type 1-homozygous-knockout mice （IL-1R1^-/-） and their wild-type littermates （WT） were orally inoculated with H pylori （Hp group）, while other cohorts received oral inoculation of culture medium （Cont group）. Thirteen weeks after the inoculation, the mice were examined. The plasma and stomach ghrelin levels and the gastric preproghrelin mRNA were measured.RESULTS： Although the WT mice with Hpyloriinfection showed a significantly decreased body weight as compared with that of the animals without HpyloriinfecUon,Hpyloriinfection did not influence the body weight of the IL-1Rl-knockout （IL-1R1^-/-） mice. In the Hpylori-infected IL-1R1＋ mice, the total and active ghrelin levels in the plasma were significantly increased, and the gastric ghrelin level was decreased. No significant differences were noted in the gastric preproghrelin mRNA expression.CONCLUSION： Ghrelin secretion triggered by H pylori infection might be suppressed by IL-1β, the release of which is also induced by the infection, resulting in the body weight loss of mice with Hpyloriinfection.

Metastasis-associated protein 1 induces VEGF-C and facilitates lymphangiogenesis in colorectal cancer

AIM:To study the correlation between high metastasisassociated protein 1(MTA1)expression and lymphangiogenesis in colorectal cancer(CRC)and its role in production of vascular endothelial growth factor-C(VEGF-C). METHODS:Impact of high MTA1 and VEGF-C expression levels on disease progression and lymphovasculardensity(LVD,D2-40-immunolabeled)in 81 cases of human CRC was evaluated by immunohistochemistry. VEGF-C mRNA and protein expressions in human LoVo and HCT116 cell lines were detected by real-time polymerase chain reaction and Western blotting,respectively,with a stable expression vector or siRNA. RESULTS:The elevated MTA1 and VEGF-C expression levels were correlated with lymph node metastasis and Dukes stages(P<0.05).Additionally,high MTA1 expression level was correlated with a large tumor size(P< 0.05).A significant correlation was found between MTA1 and VEGF-C protein expressions in tumor cells(r=0.371, P<0.05).Similar to the VEGF-C expression level,high MTA1 expression level was correlated with high LVD in CRC(P<0.05).Furthermore,over-expression of MTA1 significantly enhanced the VEGF-C mRNA and protein expression levels,whereas siRNAs-knocked down MTA1 decreased the VEGF-C expression level. CONCLUSION:MTA1,as a regulator of tumor-associated lymphangiogenesis,promotes lymphangiogenesis in CRC by mediating the VEGF-C expression.

Current Status of Studies on Targeted Therapy for Renal Cell Carcinoma

Renal cell carcinoma(RCC)is regarded as one of the most refractory malignancies.A further study of the molecular mechanism of RCC formation has led to a series of successful examples for treatment of patients with advanced RCC.Over the past 20 years,a nonspecific immunotherapy,with cytokines,has been employed as the gold standard for therapy of metastatic RCC.However,with scientific development and clinical testing of new drugs,targeted molecular cancer therapy has become a focus of interest.At the same time,with a better understanding of RCC, the treatment method has converged on anti-vascular endothelial growth factor(VEGF)and related molecular-targeted pathways. A large amount of research and numerous clinical trials have demonstrated the clinical efficacy of the targeted molecular therapies in patients with metastatic RCC.For example sorafenib and sunitinib were approved,in 2005 and 2006 respectively,by the U.S.FDA for treating advanced RCC.In this report,issues such as the importance of VEGF in RCC and the studies of bevacizumab, sunitinib and sorafenib in treating metastatic RCC etc.,are reviewed.

Expression of VEGF-C and b-FGF in Lung Cancer and Its Relationship with Cancer Progress

Objective： to observe expression of vascular endothelial growth factor-C （VEGF-C） and alkaline fibroblast growth factor （b-FGF） in tissues of lung cancer, and its relationship with cancer metastasis.Methods： to adopt immunohistochemical methods, analysis of 60 cases of lung tissue expression of VEGF-C and b-FGF in the situation.Result： positive rates of VEGF-C and b-FGF in lung cancer are respectively 56.67% and 63.33%; expression of VEGF-C and b-FGF in lung cancer is not related to pathological grades, pathologic stages or ages of patients （P 〉 0.05）,but closely related to TNM stages and existence of lymph node metastasis （P 〈 0.01）. IMVD in center of lung cancer tissues is obviously higher than surrounding area, with significant differences （P 〈 0.01）. Conclusion： expression of VEGF-C and b-FGF is related to lung cancer progress.

帽儿山温带落叶阔叶林细根生物量、生产力和周转率

细根在森林生态系统能量流动与物质循环中占有重要地位,但其生物量、生产和周转测定尚存在很大的不确定性,而且局域尺度空间变异机制尚不清楚。本研究分析了帽儿山温带天然次生林活细根生物量和死细根生物量在0~100 cm剖面的垂直分布与0~20 cm细根的季节动态、生产力和周转率,对比了采用连续根钻法(包括决策矩阵法和极差法)和内生长袋(直径3和5 cm)估测细根生产力和细根周转率,并探讨了可能影响细根的林分因子。结果表明:76.8%的活细根生物量和62.9%的死细根生物量均集中在0~20 cm土层,随着深度增加,二者均呈指数形式减少。活细根生物量和死细根生物量的季节变化不显著,可能与冬季几乎无降雪而夏季降雨异常多有关。2种直径内生长袋估计的细根生产力无显著差异;对数转换后决策矩阵、极差法和内生长法估计的细根生产力和细根周转率差异显著。随着土壤养分增加,活细根生物量和死细根生物量比值显著增加,死细根生物量显著减少,但活细根生物量、细根生产力和细根周转率均无显著变化;细根周转率与前一年地上木质生物量增长量呈显著正相关,但与当年地上木质生物量增长量无显著相关关系。

Long-term variability of root production in bioenergy crops from ingrowth core measurements

Aims Long-term determination of root biomass production upon land-use conversion to biofuel crops is rare.To assess land-use legacy influences on belowground biomass accumulation,we converted 22-year-old Conservation Reserve Program(CRP)grasslands and 50+-year-old agricultural(AGR)lands to corn(C),switchgrass(Sw)and restored prairie(Pr)biofuel crops.We maintained one CRP grassland as a reference(Ref).We hypothesized that land-use history and crop type have significant effects on root density,with perennial crops on CRP grasslands having a higher root biomass productivity,while corn grown on former agricultural lands produce the lowest root biomass.Methods The ingrowth core method was used to determine in situ ingrowth root biomass,alongside measurements of aboveground net primary productivity(ANPP).Ancillary measurements,including air temperature,growing season length and precipitation were used to examine their influences on root biomass production.Important Findings Root biomass productivity was the highest in unconverted CRP grassland(1716 g m?2 yr?1)and lowest in corn fields(526 g m?2 yr?1).All perennial sites converted from CRP and AGR lands had lower root biomass and ANPP in the first year of planting but peaked in 2011 for switchgrass and a year later for restored prairies.Ecosystem stability was higher in restored prairies(AGR-Pr:4.3±0.11;CRP-Pr:4.1±0.10),with all monocultures exhibiting a lower stability.Root biomass production was positively related to ANPP(R2=0.40).Overall,attention should be given to root biomass accumulation in large-scale biofuel production as it is a major source of carbon sequestration.

Acupotomy versus sodium hyaluronate for treatment of knee osteoarthritis in rabbits

OBJECTIVE: To investigate the possible advantages of acupotomy over sodium hyaluronate injection for the treatment of knee osteoarthritis(KOA).METHODS: Twenty rabbits were divided randomly into four groups(n = 5 in each): a control group,model group, acupotomy group, and sodium hyaluronate injection group. The model, acupotomy,and sodium hyaluronate groups underwent anterior cruciate ligament transection plus partial medial meniscectomy. Sodium hyaluronate injection and acupotomy were administered to the respective groups from weeks 5 to 8, and samples of the tibial plateau and medial condyle of the femur were collected in week 9. Vascular endothelial growth factor(VEGF) expression was assessed in cartilage and subchondral bone by immunohistochemical staining.RESULTS: Articular cartilage degeneration was less pronounced in the acupotomy compared with the model and sodium hyaluronate groups. VEGF expression levels in cartilage and subchondral bone were increased in the model group compared with the control group(P < 0.01), and acupotomy had a more pronounced therapeutic effect than sodium hyaluronate injection(P < 0.01).CONCLUSION: Acupotomy and sodium hyaluronate injection may both reduce degeneration in the cartilage and subchondral bone in KOA based on the results from a rabbit model, but acupotomy improved the histopathology and reduced the VEGF content more effectively than sodium hyaluronate injection, probably by reducing venous stasis and intraosseous pressure. Acupotomy may improve KOA by lowering VEGF.