荒漠草原土壤微生物矿化对灌丛引入过程及水分的响应

以宁夏荒漠草原封育草地（封育14年）、放牧地为对照,开展不同年限（3a、12a、22a）和间距（40 m、6 m、2 m）柠条地（Caragana korshinskii）灌丛引入过程土壤微生物矿化及对不同水分梯度（自然降雨、前期饱和、持续干旱）响应特征研究。结果表明：灌丛地0-20 cm和0-100 cm土层土壤全氮含量均高于放牧地且随年限和密度增加呈增高趋势,分别为0.28-0.42、0.27-0.42 g/kg和0.28-0.51、0.27-0.51 g/kg,但在22年且密度增至2 m间距的灌丛地与封育草地相比差异不显著或呈降低趋势;微生物量氮变化分别为0.041-0.057、0.041-0.081 mg/kg,且22年灌丛地呈显著降低,2 m间距灌丛地呈显著增加,但均显著低于封育草地0.079 mg/kg和放牧地0.103 mg/kg （P<0.05）;真菌/细菌比值随灌丛地年限和密度增加变化为0.06-0.33,均高于封育草地0.04和放牧地0.03（P<0.05）,微生物变化改变了灌丛地的矿化过程,相较封育草地0.003 mg kg^-1 d^-1和放牧地-0.068 mg kg^-1 d^-1的净矿化速率,不同年限/间距灌丛地虽分别降低为-0.155--0.084、-0.116--0.061 mg kg^-1 d^-1,但均表现为前期加速硝化过程,使得硝态氮则随年限和密度增加呈增加趋势显著高于两样地,而铵态氮变化则较为稳定;封育草地对干旱具缓冲作用,持续矿化,而放牧地和灌丛地净矿化速率对水分降低响应积极,分别降低280.3%和440.2%,其中放牧地和灌丛地以硝化作用变化尤为显著,特别是灌丛地则随干旱加剧净硝化速率均呈显著降低趋势（P<0.05）,其净矿化速率变化以硝化过程占主导。     

湖北黑麦草属(禾本科)一新种

大穗黑麦草　新种　图１LoliumgrandispicumY.J.Feisp.nov.Fig.1Speciesnovapeculiaris,aLperenneL.differtvaginisinternodiislongioribus,foliismarginecurvispinulis;peniculisspiciformibus,spiculisinternodiisrhachillarumscalaribusinversisconfertispeleis,paleis...     

中国锦鸡儿属植物资源研究—分布及分种描述

记录了锦鸡儿属（Cargana Fabr.)植物的资源分布,并对该属66种植物（小叶锦鸡儿,柠条锦鸡儿,中间锦鸡儿,树锦鸡儿,黄刺条,锦鸡儿,红花锦鸡儿,密叶锦鸡儿,鬼箭锦鸡儿,毛掌叶锦鸡儿,白毛锦鸡儿,甘蒙锦鸡儿,矮锦鸡儿,繁花锦鸡儿,矮脚锦鸡儿,狭叶锦鸡儿,毛刺锦鸡儿,柄荚锦鸡儿,秦晋锦鸡儿,北京锦鸡儿,南口锦鸡儿,五台锦鸡儿,昆仑锦鸡儿,库车锦鸡儿,短叶锦鸡儿,变色锦鸡儿,二色锦鸡儿,白皮锦鸡儿,青甘锦鸡儿,川西锦鸡儿,云南锦鸡儿,猫耳锦鸡儿,陕西锦鸡儿,长爪锦鸡儿,甘肃锦鸡儿,扁刺锦鸡儿,青海锦鸡儿,二连锦鸡儿,弯枝锦鸡儿,昌都锦鸡儿,楔翼锦鸡儿,高山锦鸡儿,藏北锦鸡儿,尼泊尔锦鸡儿,沦江锦鸡儿,吉降职一锦鸡儿,文县锦鸡儿,粗刺锦鸡儿,西藏锦鸡儿,刺锦鸡儿,粉刺锦鸡儿,草原锦鸡儿,阿拉套锦鸡儿,伊犁锦鸡儿,阿尔泰锦鸡儿,镰叶锦鸡儿,中亚锦鸡儿,邦卡锦鸡儿,绢毛锦鸡儿,白刺锦鸡儿,多叶锦鸡儿,新疆锦鸡儿,刺叶锦鸡儿,粗毛锦鸡儿,准噶尔锦鸡儿,吉尔吉斯锦鸡儿）的特征,习性及分布进行了详细描述。     

Separation and identification of neuropeptide Y, two of its fragments and their degradation products using capillary electrophoresis–mass spectrometry

This paper describes the development of an analytical method for the separation and identification of neuropeptide Y (NPY) and two important NPY fragments by capillary electrophoresis (CE) and mass spectrometry (MS). A satisfactory separation and the highest sensitivity were obtained with formic acid at high concentrations (250 mM, pH 2.75). The addition of 25 or 50 mM triethylamine (TEA) improved the separation. When applying full scan CE–MS, the separated peptides could be detected and identified using the spectra of each peak. The use of TEA as an additive to the formic acid slightly decreased the sensitivity but was compensated by the improved efficiency. The best compromise for optimal separation and MS detection was found to be 50 mM formic acid to which 50 mM TEA was added. CE–MS could be used for identification of the decomposition products of NPY. Decomposition products with one amino acid difference, which could not be distinguished with CE–UV, could be distinguished with CE–MS.     

The Chemical Constituents of Garctnia xishuanbannanensis Y. H. Li Native to China

Garcinia xishuanbannanensis Y. H. Li is a rare tree species belonging to the Guttiferae and endemic in Xishuangbanna District of Yunnan. From its stem-bark two polyisoprenyl benzophenones-xanthochymol and isoxanthochymol have been isolated. They were identified on the basis of physico-chemical properties and UV, IR, 1HNMR, 13CNMR and MS analysis. The test of antitumor and antibacteria properties of these two compounds in mam- mals will be reported subsequently.     

Molecular characterization of the ligand–receptor interaction of the neuropeptide Y family

Neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP) belong to the NPY hormone family and activate a class of receptors called the Y‐receptors, and also belong to the large superfamily of the G‐protein coupled receptors. Structure–affinity and structure–activity relationship studies of peptide analogs, combined with studies based on site‐directed mutagenesis and anti‐receptor antibodies, have given insight into the individual characterization of each receptor subtype relative to its interaction with the ligand, as well as to its biological function. A number of selective antagonists at the Y₁‐receptor are available whose structures resemble that of the C‐terminus of NPY. Some of these compounds, like BIBP3226, BIBO3304 and GW1229, have recently been used for in vivo investigations of the NPY‐induced increase in food intake. Y₂‐receptor selective agonists are the analog cyclo‐(28/32)‐Ac‐[Lys²⁸‐Glu³²]‐(25–36)‐pNPY and the TASP molecule containing two units of the NPY segment 21–36. Now the first antagonist with nanomolar affinity for the Y₂‐receptor is also known, BIIE0246. So far, the native peptide PP has been shown to be the most potent ligand at the Y₄‐receptor. However, by the design of PP/NPY chimera, some analogs have been found that bind not only to the Y₄‐, but also to the Y₅‐receptor with subnanomolar affinities, and are as potent as NPY at the Y₁‐receptor. For the characterization of the Y₅‐receptor in vitro and in vivo, a new class of highly selective agonists is now available. This consists of analogs of NPY and of PP/NPY chimera which all contain the motif Ala³¹‐Aib³². This motif has been shown to induce a 3₁₀‐helical turn in the region 28–31 of NPY and is suggested to be the key motif for high Y₅‐receptor selectivity. The results of feeding experiments in rats treated with the first highly specific Y₅‐receptor agonists support the hypothesis that this receptor plays a role in the NPY‐induced stimulation of food intake. In conclusion, the selective compounds for the different Y‐receptor subtypes known so far are promising tools for a better understanding of the physiological properties of the hormones of the NPY family and related receptors. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.