格网尺度下典型旅游城市生态服务价值估算和时空分异特征——以三亚为例

以典型旅游城市三亚市为案例地，利用2006-2018年4期Landsat遥感影像数据，借助ENVI、ArcGIS平台定量识别土地利用演变特征，在1km×1km格网尺度下估算旅游地生态系统服务价值，并结合空间探索性数据分析揭示生态系统服务价值时空分异特征及其与旅游地发展的时空耦合关系。结果表明：（1）2006-2018年间，三亚市生态系统服务价值总量呈逐年下降趋势，由6.73×10⁹元降至5.76×10⁹元，累计减少9.78×10⁸元；（2）空间格局上，三亚市呈"南低北高"空间分异格局，2006-2018年增值区域连片分布于崖州区、天涯区、吉阳区南部区域，且呈逐年减少趋势，减值区域集聚于天涯区东北部、海棠区；（3）空间集聚上，生态系统服务价值截面各年份均呈显著空间正相关且相关性先降后增。高高集聚区位于天涯区北部区域，低低集聚区分布于沿海、海湾地区；（4）旅游发展与生态系统服务价值时空演化特征关联性较强。三亚市天涯区北部林地生态环境良好，生态系统服务价值略有下降但绝对数值稳定，是生态系统服务价值主要来源；旅游发展较为迅速的三亚湾、崖州湾以及海棠湾，相对增值区域较多，但绝对生态系统服务价值损失显著，严重滞后于其他区域。     

α‐ketoglutarate delays age‐related fertility decline in mammals

The fecundity reduction with aging is referred as the reproductive aging which comes earlier than that of chronological aging. Since humans have postponed their childbearing age, to prolong the reproductive age becomes urgent agenda for reproductive biologists. In the current study, we examined the potential associations of α‐ketoglutarate (α‐KG) and reproductive aging in mammals including mice, swine, and humans. There is a clear tendency of reduced α‐KG level with aging in the follicle fluids of human. To explore the mechanisms, mice were selected as the convenient animal model. It is observed that a long term of α‐KG administration preserves the ovarian function, the quality and quantity of oocytes as well as the telomere maintaining system in mice. α‐KG suppresses ATP synthase and alterations of the energy metabolism trigger the nutritional sensors to down‐regulate mTOR pathway. These events not only benefit the general aging process but also maintain ovarian function and delay the reproductive decline. Considering the safety of the α‐KG as a naturally occurring molecule in energy metabolism, its utility in reproduction of large mammals including humans deserves further investigation.     

Optimal Sequence of Irinotecan and Oxaliplatin-Based Regimens in Metastatic Colorectal Cancer: A Population-Based Observational Study

The optimal sequence of irinotecan and oxaliplatin-based regimens for metastatic colorectal cancer remains unclear. We conducted a population-based observational study by retrospectively reviewing records from Taiwan’s National Health Insurance Research Database to explore this issue. Patients aged ≥20 years with metastatic colorectal cancer newly diagnosed between 2004 and 2008 (n = 9490) were enrolled in current study. Among these 9490 patients, 3895 patients (41.04%) did not receive any chemotherapy within the first three months after catastrophic illness registration. Patients who received best supportive care were older and had higher Charlson comorbidity indexes and incidences of comorbidities than those who received irinotecan-based regimens, oxaliplatin-based regimens, and 5-fluorouracil/capecitabine alone. Patients who received irinotecan followed by oxaliplatin-based regimens and those who received the reverse sequence were further stratified into arm A (n = 542) and arm B (n = 1156), respectively. The median first time to next treatment was not significantly different between arm A and arm B (210 days vs. 196 days; p = 0.17). However, the median second time to next treatment was longer in arm A than in arm B (155 days vs. 123 days; p = 0.006), which translated into a better overall survival (487 days vs. 454 days; p = 0.02). The crossover rate was higher in arm A than in arm B (47.84% vs. 41.61%; p<0.001). Multivariate Cox regression analyses showed that overall survival was comparable between the two chemotherapy sequences (p = 0.27). Our study suggested that irinotecan followed by oxaliplatin-based regimens might be a better chemotherapy treatment option for metastatic colorectal cancer than the reverse sequence given the higher crossover rate and potential overall survival benefit.     

Reaction mechanism of surfactant‐sensitized chemiluminescence of bis(2,4,6‐trichlorophyenyl) oxalate and hydrogen peroxide induced by gold nanoparticles

The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Quantification of müllerian inhibiting substance in developing chick gonads by a competitive enzyme-linked immunosorbent assay

An immunoblotting method was used to purify a Müllerian-inhibiting substance (MIS)-specific antiserum. The serum was used to quantify the content of MIS in developing chick gonads by competitive enzyme-linked immunosorbent assay. From embryonic stages to the eleventh week after hatching, male chicken testes have a high content of MIS in the following two stages: (1) from the sixth to the eighth day and from the fourteenth to the twentieth day of incubation, and (2) from the second to the eighth week after hatching. The high content of MIS in the early embryonic stage is closely correlated with the natural pattern of Müllerian duct regression observed in the male embryo. From the sixth to the twelfth day of incubation, the female right ovary contains a higher content of MIS than that of the left ovary. Up to the fourteenth day of incubation, the content of MIS in the left ovary reaches maximum levels and then declines. The combination of MIS from right and left ovaries was found to be highest in the ninth to the fourteenth day of incubation, when the regression of the right Müllerian duct reached its highest peak. However, the question of the inability of MIS to cause regression of the female left Müllerian duct and the caudal part of the right duct is raised and discussed. The hypothesis that prenatal estrogenic hormone (diethylstilbestrol) protects the Müllerian duct has been reevaluated. It was found that estrogen does not reduce the MIS content in prenatally treated gonads.     

The androgen-dependent mouse seminal vesicle secretory protein IV: characterization and complementary deoxyribonucleic acid cloning

Seminal vesicle secretory protein IV of a mouse has been isolated, and the cDNA coding for its mRNA has been cloned and sequenced. The 556-nucleotides encode 16 amino acid signal peptides and 92 residues of mature protein. Considerable homology between mouse and rat SVS IV cDNA was found. In the leader peptide and 3'-noncoding region there is 92% and 85% homology, respectively. The other regional homologies are 86% for the first 12, 68.5% for the last 35, and 40% for the middle 44 amino acids. The expression of mouse SVS IV mRNA is under the control of androgen. Administration of testosterone to castrated mice resulted in induction of the mRNA level to 50% of the mature male in 96 h of hormone treatment. Secretion of the protein after testosterone injection follows a similar pattern.     

Determination of immunoreactive endothelin in medium from cultured endothelial cells and human plasma

We have developed a sensitive and selective radioimmunoassay for porcine/human endothelin (ET1). The assay has a detection limit of 0.62 pg/tube and exhibits no cross-reactivity to atrial natriuretic peptide, arginine vasopressin, or angiotensin II. Procedures were developed for extraction of endothelin from human plasma samples and samples of buffer from endothelial cell incubations using C18 Sep-Pak extraction cartridges. The mean recovery following extraction was approximately 80%. Both bovine and porcine aortic endothelial cells were found to produce immunoreactive endothelin (IR-ET) with porcine cells producing 4.7 +/- 1.1 ng of IR-ET/mg cell protein after 6 hours. Human plasma samples were extracted, assayed and found to contain a mean concentration of 2.0 +/- 0.4 pg/ml of IR-ET.     

麦田冠层气孔导度的分层研究

小麦灌浆期和乳熟期冠层各层叶片上、下表面的气孔导度之间呈正相关关系;冠层不同层的叶片气孔导度从早到傍晚有平行变化的趋势,数值上存在较大的差异,一般从冠层上到下递减。经分析,这主要与冠层叶片接受的光强自上而下递减有关,且这时所对应的叶片水势自冠层上到下递增的幅度大。测算结果表明,冠层气孔导度白天亦呈明显的日变化,灌浆期的值大于乳熟期的值。