Peroxisome Proliferator-activated Receptor-D (PPARD) Coordinates Mouse Spermatogenesis by Modulating Extracellular Signal-regulated Kinase (ERK)-dependent Signaling

Ppard^−/− mice exhibit smaller litter size compared with Ppard^+/+ mice. To determine whether peroxisome proliferator-activated receptor-D (PPARD) could possibly influence this phenotype, the role of PPARD in testicular biology was examined. Atrophic testes and testicular degeneration were observed in Ppard^−/− mice compared with Ppard^+/+ mice, indicating that PPARD modulates spermatogenesis. Higher expression of p27 and decreased expression of proliferating cellular nuclear antigen in Sertoli cells were observed in Ppard^+/+ mice as compared with Ppard^−/− mice, and these were associated with decreased Sertoli cell number in Ppard^+/+ mice. Cyclin D1 and cyclin D2 expression was lower in Ppard^+/+ as compared with Ppard^−/− mice. Ligand activation of PPARD inhibited proliferation of a mouse Sertoli cell line, TM4, and an inverse agonist of PPARD (DG172) rescued this effect. Temporal inhibition of extracellular signal-regulated kinase (ERK) activation by PPARD in the testis was observed in Ppard^+/+ mice and was associated with decreased serum follicle-stimulating hormone and higher claudin-11 expression along the blood-testis barrier. PPARD-dependent ERK activation also altered expression of claudin-11, p27, cyclin D1, and cyclin D2 in TM4 cells, causing inhibition of cell proliferation, maturation, and formation of tight junctions in Sertoli cells, thus confirming a requirement for PPARD in accurate Sertoli cell function. Combined, these results reveal for the first time that PPARD regulates spermatogenesis by modulating the function of Sertoli cells during early testis development.     

Myocardial remodeling in rats with metabolic syndrome: role of Rho-kinase mediated insulin resistance

Insulin resistance (IR) plays a critical role in metabolic syndrome (MS). Previous studies have demonstrated that activated ROCK is increased in MS patients. However, the effect of Rho-kinase (ROCK) on IR has not been definitely determined. Thus, the aims of the present study were to determine whether ROCK activation induces IR or affects myocardial structure and function, as well as the possible mechanisms underlying this process. Wistar rats fed high fat, high glucose and high salt diet sewed as model of MS and we used transmission electron microscopy, echocardiogram technology, and terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling staining to identify any myocardial damage. The protein levels of MYPT-1 (characteristic of ROCK activation), IRS-1 and AKT were analyzed by immunohistochemistry and Western blotting. In hearts from MS rats, we found increased protein levels of phospho-MYPT-1 and phospho-IRS-1 (Ser307) and decreased phospho-AKT compared to levels in normal rats. In conclusion, the results suggest that ROCK-mediated IR is involved in the development of myocardial impairments in MS rats and that this effect is mediated probably via the IRS-1/PI3-kinase/AKT pathway.     

热带喀斯特森林常绿和落叶榕树的水力特征和水分关系与抗旱策略

以热带喀斯特地区的直脉榕(Ficus orthoneura)和豆果榕(F.pisocarpa)为实验材料,研究了常绿和落叶树木枝条和叶片的解剖结构特征、光合水分特征和耐旱性的差异,目的在于探讨不同生活型榕树适应干旱生境的策略.直脉榕和豆果榕的叶片都有两层栅栏组织、游离状的海绵组织和钟乳体等旱生结构,同时叶片角质层蒸腾速率(gmin)和气孔导度(gs)相对较低.但与落叶的豆果榕相比,常绿的直脉榕的枝条木质部失去50％传导率的水势(P50)和gmin更低,表现出更保守的水分利用策略.总体上,两种榕树都表现出了对喀斯特干旱生境的良好适应,但是它们的适应策略表现出一定的差别.豆果榕通过落叶度过旱期,而直脉榕在结构和功能上比豆果榕更耐旱.抗旱策略和水分利用策略的不同导致两种榕树的生态位分异,减少了彼此间的水分竞争,有利于它们在喀斯特生境中共存.     

Global expression profiling of theophylline response genes in macrophages: evidence of airway anti-inflammatory regulation

Background

Theophylline has been used widely as a bronchodilator for the treatment of bronchial asthma and has been suggested to modulate immune response. While the importance of macrophages in asthma has been reappraised and emphasized, their significance has not been well investigated. We conducted a genome-wide profiling of the gene expressions of macrophages in response to theophylline.

Methods

Microarray technology was used to profile the gene expression patterns of macrophages modulated by theophylline. Northern blot and real-time quantitative RT-PCR were also used to validate the microarray data, while Western blot and ELISA were used to measure the levels of IL-13 and LTC4.

Results

We identified dozens of genes in macrophages that were dose-dependently down- or up-regulated by theophylline. These included genes related to inflammation, cytokines, signaling transduction, cell adhesion and motility, cell cycle regulators, and metabolism. We observed that IL-13, a central mediator of airway inflammation, was dramatically suppressed by theophylline. Real-time quantitative RT-PCR and ELISA analyses also confirmed these results, without respect to PMA-treated THP-1 cells or isolated human alveolar macrophages. Theophylline, rolipram, etazolate, db-cAMP and forskolin suppressed both IL-13 mRNA expression (~25%, 2.73%, 8.12%, 5.28%, and 18.41%, respectively) and protein secretion (<10% production) in macrophages. These agents also effectively suppressed LTC4 expression.

Conclusion

Our results suggest that the suppression of IL-13 by theophylline may be through cAMP mediation and may decrease LTC4 production. This study supports the role of theophylline as a signal regulator of inflammation, and that down regulation of IL-13 by theophylline may have beneficial effects in inflammatory airway diseases.     

降水量变化对藏北高寒草地养分限制的影响

生态系统净初级生产养分限制的模式是现代生态学关注的重要问题。养分的可利用性是草原生态系统生产力动态变化的关键决定因素, 但土壤养分可利用性与整个生态系统中养分限制之间的关系尚不清楚。该研究通过在藏北降水梯度上4种类型高寒草地(从东到西依次是高寒草甸、高寒草甸草原、高寒草原和高寒荒漠草原)设置氮磷养分添加试验, 系统研究氮磷养分添加对不同类型高寒草地的影响, 并探讨降水梯度上高寒草地的氮磷限制模式。结果表明: (1)氮磷添加对不同高寒草地的影响存在差异: 氮添加显著提高了高寒草甸和高寒草甸草原地上生产力, 而对高寒草原和高寒荒漠草原无影响; 单独磷添加对4种高寒草地均无显著影响, 而氮磷添加对4种高寒草地地上生产力均有促进作用。(2)通过计算氮磷共同限制指数发现: 随着降水量减少, 高寒草地氮限制指数从1.18逐渐降低到0.52-0.64, 养分限制模式从氮限制过渡到氮磷共同限制; 磷限制指数在高寒草甸草原和高寒草原为负值, 说明单独磷添加对高寒草甸的生产力有负向作用, 高寒草甸主要受氮限制; 高寒草甸草原介于氮限制与氮磷限制之间, 受到氮磷共同限制, 单独磷添加有负向作用; 高寒荒漠草原受到氮磷共同限制。研究表明, 高寒草地氮磷限制模式存在环境梯度上的递变规律, 随着降水量减少, 高寒草地养分限制模式从氮限制逐渐过渡到氮磷共同限制。由此推断, 未来气候变化条件下氮沉降增加对不同类型高寒草地的影响可能存在差异。同时, 利用养分添加恢复不同类型退化高寒草地时也应将氮磷限制模式的差异考虑进去。     

季节性冻融期间川西亚高山/高山森林土壤净氮矿化特征

气候变暖情景下季节性冻融格局的改变可能显著影响高寒森林土壤氮素矿化过程.本文采用原状土壤移位培养的方法,以海拔梯度形成的温度差异模拟气候变暖,研究了川西亚高山/高山森林在生长季节和季节性冻融期间土壤的净氮矿化量和净氮矿化速率.结果表明： 在川西亚高山/高山森林,土壤铵态氮和硝态氮含量均表现为从生长季节至冻结初期明显下降,完全冻结期明显增加,而在融化初期明显降低的变化过程.季节性冻融期土壤的净氮矿化量和净氮矿化速率显著低于生长季节,并且出现明显的氮素固持现象.与低海拔相比,中海拔森林土壤的氮素固持作用相对较大,高海拔相对较小,可能与不同海拔梯度土壤温度变化及引起的冻融循环密切相关.在生长季节,土壤净氮矿化量和矿化速率均随海拔的降低呈明显增加趋势,尤其在低海拔处土壤的氮素矿化作用最为强烈.在气候变暖背景下,温度的增加明显促进了生长季节土壤氮素矿化,并且通过提高冻融循环频次、缩短冻结时间来影响土壤氮素矿化速率.这一过程可能受到微环境的影响.     

游动分割窗技术在生态交错带定量判定中的应用:以四川巴郎山岷江冷杉林线为例

以样带上样方间的距离系数为指标 ,采用游动分割窗技术辨析了岷江冷杉 (Abiesfaxoniana)林线附近交错带的位置和宽度。结果表明 ,Bray_Curtis距离、相对欧氏距离、弦距离与平方欧氏距离的峰值和峰宽具有很好的重合性 ,上述距离系数均能作为判定林线交错带群落的边界和宽度的优良指标 ,其中 ,平方欧氏距离更能直观和准确地反映交错带植被的变异。样带上距离系数的峰值区和峰宽对生态交错带的位置和宽度有较为敏感的指示意义 ,游动分割窗技术是交错带判定和群落划分的有效方法。