土壤翻耕影响坡地磷流失试验研究

以黄绵土为试验材料,通过模拟降雨试验研究了翻耕与压实(分别代表大田条件下土壤翻耕与免耕两种休闲方式)条件下坡地土壤中不同形态P的流失特征。结果表明,翻耕条件下,由于坡面产流产沙量增加,流失径流中溶解态磷(DP)、泥沙浸提态磷(SEP)以及泥沙全磷(STP)的含量与流失量均明显增加,增幅达10倍以上,P的流失形态以泥沙结合态为主,压实条件下,DP／生物有效磷(BAP)与BAP／径流总磷(TP)比率分别为15％和2．4％;而翻耕条件下DP／BAP与BAP／TP比率分别为12％和2．6％,在黄土高原地区实行免耕或者夏季留茬休闲,可有效降低坡地土壤与养分的流失量,有效遏制土壤退化,对于保护下游水环境具有重要意义。     

长兴县合溪水库集雨区苗木地不同施肥管理模式对径流磷素流失的影响

为保护主要饮用水源合溪水库水质,长兴县将合溪水库集雨区农业种植结构向苗木种植方式调整,但缺乏优化施肥管理模式。针对该问题,选取集雨区典型苗木种植地进行径流小区定位试验,设置了撒施(对照)、地膜覆盖、秸秆覆盖、区外设置植草缓冲带、条施、穴施6个处理,研究不同施肥管理模式下苗木地径流磷素流失特征,筛选最优施肥管理模式,实现最大化的削减农田磷素流失。结果表明:不同施肥管理模式下,苗木地地表径流年总磷素径流流失通量大小顺序为:撒施(对照)地膜覆盖条施穴施区外植草缓冲带秸秆覆盖,撒施(对照)、地膜覆盖、条施、穴施、区外设置植草缓冲带和秸秆覆盖六种施肥管理模式下的年总磷素径流流失通量分别为:9.60、9.14、5.49、4.44、2.48、1.37 kg hm-2a-1,说明穴施、区外设置植草缓冲带和秸秆覆盖是较佳的施肥管理模式,若将其优化组合将显著消减合溪水库集雨区苗木地径流磷素流失及其对合溪水库水质的潜在影响。此外,不同施肥管理模式下,苗木地径流水样磷素流失的首要形态均为颗粒态磷,其次为溶解态磷,其中,撒施(对照)、地膜覆盖、秸秆覆盖、区外植草缓冲带、条施和穴施小区径流年均流失的颗粒态磷占流失总磷的比例分别是66.09%、70.69%、67.97%、71.63%、68.11%和67.87%。     

鸡眼草水浸提液对4种草坪草的化感作用

为探讨鸡眼草(Kummerowia striata)不同部位、不同浓度水浸提液对高羊茅(Festuca arundinacea)、黑麦草(Lolium perenne)、狗牙根(Cynodon dactylon)、白三叶(Trifolium repens)等4种草坪草的化感效应和作用规律,采用培养皿纸床法,以蒸馏水为对照,研究鸡眼草剪碎的植株、未剪碎的植株、叶、茎、根、地上部分0.012 5、0.025、0.05 g/mL 3个不同浓度的水浸提液对高羊茅、黑麦草、狗牙根、白三叶的种子发芽率、发芽速率、幼根长、幼苗高的化感作用。结果表明,鸡眼草水浸提液对高羊茅、黑麦草、狗牙根、白三叶4种受体植物种子的萌发及幼苗生长均有较强的化感抑制作用,且对种子发芽率作用强弱顺序为:狗牙根白三叶黑麦草高羊茅,对种子发芽速率作用强弱顺序为:黑麦草高羊茅狗牙根白三叶,对幼苗苗高作用强弱顺序为:黑麦草白三叶狗牙根高羊茅,对幼苗根长作用强弱顺序为:白三叶黑麦草狗牙根高羊茅。对4种受体植物的综合化感效应以高羊茅最弱,黑麦草、狗牙根、白三叶较为相近。4种受体植物所受到的抑制作用均随着水浸提液浓度的增加而增强,在同一浓度不同部位水浸提液处理下,叶、整株(剪碎)水浸提液对4种受体植物抑制作用比根、茎、整株(未剪碎)及地上部分水浸提液强。高羊茅、黑麦草、狗牙根3种草坪草受0.05 g/mL鸡眼草叶水浸提液的化感抑制作用最强,白三叶则受0.05 g/mL鸡眼草整株(剪碎)水浸提液的化感抑制作用最强。     

湘南红壤丘陵区不同生态种植模式下土壤磷素流失特征

以湖南省祁阳县红壤坡地大型标准径流场为例,研究了湘南红壤丘陵区8种不同生态种植模式下土壤磷素的地表流失特征.结果表明: 总磷流失量以撂荒处理(T₁)最严重,顺坡种植模式处理(T₂、T₃)其次,5种梯田模式处理(T₄～T₈)均能有效减少土壤磷的流失,磷流失量分别是T₁处理的9.9%、37%、0.7%、2.3%和1.9%.生态种植模式直接影响红壤坡地土壤磷素的地表流失形态,研究区流失的磷素以颗粒磷为主.暴雨(日降雨量＞50 mm)情况下,降雨量对不同生态种植模式下磷流失量影响差异不大,但磷流失量随降雨强度增大而增加.红壤坡地土壤磷素地表流失主要集中在6-9月,降雨量和降雨强度是影响湘南红壤丘陵区土壤磷素地表流失时间分布的直接因素.
     

水网平原地区不同种植类型农田氮磷流失特征

采用田间径流小区定位研究方法,在浙江省绍兴县选择27块农田,研究了自然降雨条件下水网平原地区7种种植类型农田N、P的径流流失特征、负荷及影响因素.结果表明： 农田径流总P（TP）、水溶态P（DP）和颗粒态P（PP）的年流失量平均分别为4.75、0.74和4.01 kg·hm^-2;PP占TP的比例高于DP.径流总N（TN）、水溶态总N（DTN）、水溶态有机N（DON）、NH₄⁺-N和NO₃^--N的年流失量平均分别为21.87、17.19、0.61、3.63和12.95 kg·hm^-2;流失的DTN各组分以NO₃^--N为主,其次为NH₄⁺-N,DON的比例较低.不同种植类型农田径流TN、DTN、DON和NO₃^--N的流失量由低至高依次为：休闲地<苗木地<单季晚稻农田<双季稻农田<油菜(或小麦)-单季水稻农田<小麦-早稻-晚稻农田<蔬菜地,而径流TP和PP的流失量依次为：休闲地<苗木地<单季晚稻、双季稻农田<小麦-早稻-晚稻农田<油菜(或小麦)-单季水稻农田<蔬菜地,不同种植类型间的DP流失量差异较小.N、P流失主要发生在作物生产期间,TN和TP的流失比例随作物复种指数的提高而增加.TN、DTN和NO₃^--N流失量主要与N肥施用量有关,土壤中NO₃^--N含量对TN和DTN流失量也有明显影响;农田DON的流失除与N肥施用量有关外,还受土壤全N和有机质积累的影响;NH₄⁺-N的流失量主要与土壤NH₄⁺-N水平有关,受N肥施用量的影响不明显;径流TP和PP的流失量受P肥施用量、土壤P积累的共同影响,而DP的流失与施P量关系不大,但与土壤全P和有效P都存在显著相关关系.     

阜新细河生态缓冲带阻控农田径流水中氮磷及除草剂的作用

生态缓冲带作为陆地生态系统和水生生态系统的交错地带,能够有效地拦截地表径流中氮、磷及除草剂等污染物质进入河流、湖泊。选取紫花苜蓿(Medicago sativa)、早熟禾(Poa annua)、高羊茅(Festuca elata)、黑麦草(Lolium perenne)和白花三叶草(Trifolium repens)等5种草本植物构建生态缓冲带。通过野外模拟径流实验,探究植被类型及缓冲带长度对生态缓冲带阻控地表径流、铵态氮(NH₄⁺-N)、硝态氮(NO₃^--N)、总磷(TP)、溶解磷(DP)、颗粒磷(PP)、乙草胺(AC)、阿特拉津(AT)等污染物质效果的影响。结果表明：5种生态缓冲带均显著提高径流及面源污染物的阻控效率,且随缓冲带长度的增加,其对污染物阻控效率逐渐增大。不同植被生态缓冲带可有效消减地表径流量,大小依次为：黑麦草>高羊茅>早熟禾>白花三叶草>紫花苜蓿。其中,4 m长的黑麦草缓冲带对NO₃^--N、TP、DP、PP和AC...     

三峡库区消落带现存草本植物组成与生态位

为揭示经历长期水位变动后,三峡水库消落带优势植物对可利用资源的分享状况、不同资源环境下植物种群生态位特征以及植物种间竞争和共存机制,对三峡库区秭归段典型消落带现存优势草本物种的种群空间格局及生态位特征进行研究.结果表明: 该区共有草本植物39种,隶属18科32属,以禾本科、菊科、蓼科和大戟科植物为主;狗牙根、狗尾草、狼把草和毛马唐具有较大的重要值和生态位宽度,为主要优势种;海拔145～155 m段植物生态位宽度前3位依次为狗牙根＞酸模叶蓼＞狗尾草;海拔155～165 m段植物生态位宽度前3位依次为狗尾草＞毛马唐＞狗牙根;海拔165～175 m段植物生态位宽度前3位依次为狗尾草＞狼把草＞红蓼;不同海拔物种间生态位重叠均保持较高状态,生态位宽度较小物种也可与生态位宽度较大物种有较大的生态位重叠值,仅凭生态位宽度不能判定生态位重叠值.消落带经历7次水位涨落周年后,大多数优势物种为一年生草本植物,生态位分化程度较低,在资源匮乏且不稳定的生境中种间竞争强烈,消落带植被仍处于群落演替的初级阶段.     

长期深淹对三峡库区三种草本植物的恢复生长及光合特性的影响

硬秆子草（Capillipedium assimile）、双穗雀稗（Paspalum distichum）和狗牙根（Cynodon dactylon）在经受与三峡水库水位运行节律基本一致的水淹时间和水淹持续时期,但淹水深度（0、5、15和25m）不同的处理后,对其进行了恢复生长和光合特性研究。结果表明：（1）3种草本植物之间相比,狗牙根的存活率最高,所有处理植株存活率达到了100％;硬秆子草和双穗雀稗随着水淹深度的增加,存活率呈降低趋势,5in深处理存活率达到了100％,15in和25m深处理存活率在80％以上。（2）3种草本植物恢复生长后的叶片净光合速率Pn、蒸腾速率Tr、气孔导度Gs、水分利用效率WUE和表观CO2利用效率CUEapp与未淹对照相比没有显著差异;不同物种相同水淹处理之间比较,狗牙根的各光合指标显著高于硬秆子草和双穗雀稗。（3）结合三峡库区消落带植被恢复物种筛选的基本条件和本试验不同处理植株的恢复生长及其光合特性的研究,结果表明,硬秆子草、双穗雀稗和狗牙根是能够忍耐长期深淹胁迫的、适宜于三峡库区消落带植被恢复与重建的优良物种。三者之间的耐淹能力从大到小依次为：狗牙根〉硬秆子草〉双穗雀稗。     

固化技术在农村河道生态护岸中的应用

基于自主开发的固化剂,采用建筑垃圾固化桩(+植被)和土壤整体固化(+植草)技术对上海市田山庄村河道实施了护岸工程,并结合其他生态工程技术对村中污塘进行了生态重建.结果表明：由建筑垃圾制成的固化桩的抗压强度高达73 MPa,具有一定孔隙率,且硬化快、干缩小,符合生态安全性要求,在添加抗冻剂后固化桩可在-18 ℃时使用;固化桩护岸的强度较高、土壤抗侵蚀能力较强、具有较好的水力通透性,其土壤湿度与裸露河岸基本一致,对植物根系生长无明显影响;土壤整体固化后,其表面抗剪切强度比裸露河岸增加了50倍,土壤流失量仅为裸露河岸的5%;在工程实施后第10天,固化面上狗牙根草皮中部分根系开始向固化土中伸展,1个月后60%的根系深入土中,11个月后狗牙根草与固化土融为一体.固化技术与植被重建相结合,既可以满足河岸稳定性的要求,也有助于重建河岸生境.     

蚯蚓堆肥与生物炭对瓜草复合系统土壤及植株的影响研究

为探究蚯蚓堆肥与生物炭对西瓜-白三叶草生境系统的作用机制,采用温室栽培试验,设置空白对照（西瓜植株）、生物炭、覆盖三叶草、蚯蚓堆肥、覆盖三叶草+蚯蚓堆肥、生物炭+蚯蚓堆肥、覆盖三叶草+生物炭和覆盖三叶草+生物炭+蚯蚓堆肥8个处理,比较分析蚯蚓堆肥与生物炭对西瓜-白三叶草复合系统的土壤养分、微生物群落结构与主栽作物西瓜代谢组学特征。结果表明：(1)复合处理下,土壤容重降低,肥力提高,西瓜植株对氮、磷、钾养分的吸收能力增强,覆盖三叶草+生物炭+蚯蚓堆肥处理（WBV）处理综合表现最优;(2)WBV处理中微生物菌群丰富度下降,Shannon指数、Chao 1指数排序为BV＞WB＞CK＞WV＞WBV处理,与对照相比,WBV处理土壤中微生物菌群放线菌门（Actinobacteria）、变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）细菌以及被孢霉门（Mortierellomycota）真菌的相对丰度明显提升,而绿弯菌门、酸杆菌门和芽单胞菌门的相对丰度下降;(3)WBV处理西瓜果肉中检测到亚麻酸（alpha-linolenic acid）、裂解型磷脂酰胆碱(17:0)（LysoPC(17:0)）、磷酰肌醇酸(18:1(11Z)/0:0)（CPA(18:1(11Z)/0:0)）等脂质化合物,以及丙氨酸、天冬氨酸与谷氨酸等氨基酸。研究发现,覆盖三叶草+生物炭+蚯蚓堆肥复合系统可显著提高速效氮、速效磷,速效钾等土壤营养含量,促进西瓜对氮、磷元素的吸收,改善土壤微生物环境,改变西瓜植株脂质、有机酸及氨基酸的代谢水平,提升西瓜植株生物膜受保护能力和细胞渗透调节能力,增强其抗逆能力。     

Race and Racism in America and in Anthropology

Race in North America: Origin and Evolution of a Worldview . Audrey Smedley
Anthropology and Race . Eugenia Shanklin     

Degradation and conversion of somatostatin in normal and diabetic rats in vivo and in vitro

Plasma somatostatin-like immunoreactivity in the portal and jugular veins of streptozotocin diabetic rats was compared with that in normal control rats. In the diabetic group, somatostatin levels in the portal (p less than 0.05) and jugular (p less than 0.01) veins were both elevated compared with those in the control group. Moreover, the degree of elevation was greater in the jugular vein than in the portal vein. To further investigate the role of the liver in the clearance of somatostatin-28 in vivo, 2 micrograms of somatostatin-28 was administered as a bolus into the external jugular vein of intact and functionally hepatectomized rats. The mean half-time of somatostatin-28 was significantly longer in intact diabetic rats than in controls (p less than 0.05). The functional hepatectomy did not cause a significant difference in the half-time in diabetic rats but made it longer in control rats. These results suggest that the longer half-time of somatostatin-28 in diabetic rats in vivo is due to its slower hepatic clearance. The hepatic clearance of somatostatin-28 and somatostatin-14 was further studied in vitro using a recirculating liver perfusion method. The hepatic clearance of 1.2 nM of either somatostatin-28 or somatostatin-14 was significantly lower in diabetic rats than in controls (p less than 0.01). This indicates that elevated plasma somatostatin levels in diabetic rats are caused at least in part by decreased hepatic clearance of somatostatin.(ABSTRACT TRUNCATED AT 250 WORDS)     

MPD and DNA Bending in Crystals and in Solution

Bending of 15 to 24° is observed within crystal structures ofB-DNA duplexes, is strongly sequence-dependent, and exhibits no correlation with the concentration of MPD (2-methyl-2,4-pentanediol) in the crystallizing solution. Two types of bends are observed: facultative bends or flexible hinges at junctions between regions of G·C and A·T base-pairs, and a persistent and almost obligatory bend at the center of the sequence R-G-C-Y. Only A-tracts are characteristically straight and unbent in every crystal structure examined to date. A detailed examination of normal vector plots for individual strands of a double helix provides an explanation, in terms of the stacking properties of guanine and adenine bases. The effect of high MPD concentrations, in both solution and crystal, is to decrease local bending somewhat without removing it altogether. MPD gel retardation experiments provide no basis for choosing among the three models that seek to explain macroscopic curvature of DNA by means of microscopic bending: junction bending, bent A-tracts, or bent general- sequence DNA. Crystallographic data on the straightness of A-tracts, the bendability of non-A sequences, and the identity of inclination angles in A-tract and non-A-tractB-DNA support only the general-sequence bending model. The pre-melting transition observed in A-tract DNA probably represents a relaxation of stiff adenine stacks to a flexible conformation more typical of general-sequence DNA.     

Update in research and methods in proteomics and bioinformatics

The 3rd International Conference on Proteomics & Bioinformatics (Proteomics 2013)

Philadelphia, PA, USA, 15–17 July 2013

The Third International Conference on Proteomics & Bioinformatics (Proteomics 2013) was sponsored by the OMICS group and was organized in order to strengthen the future of proteomics science by bringing together professionals, researchers and scholars from leading universities across the globe. The main topics of this conference included the integration of novel platforms in data analysis, the use of a systems biology approach, different novel mass spectrometry platforms and biomarker discovery methods. The conference was divided into proteomic methods and research interests. Among these two categories, interactions between methods in proteomics and bioinformatics, as well as other research methodologies, were discussed. Exceptional topics from the keynote forum, oral presentations and the poster session have been highlighted. The topics range from new techniques for analyzing proteomics data, to new models designed to help better understand genetic variations to the differences in the salivary proteomes of HIV-infected patients.     

Parasitism and epibiosis in native and non-native gammarids in freshwater in Ireland

The introduced amphipod crustaceans Gammarus pulex and G. tigrinus are displacing the native G. ducheni celticus in a number of freshwater sites in Northern Ireland. We investigated parasite and epibiont infection in populations in the Rivet Lagan and Lough Neagh where both native and invading species occur. Prevalence of the four parasites and epibionts observed was higher in the native G. d. celticus than in the invading amphipods at both field sites. In Lough Neagh. G. d. celticus individuals suffered higher burdens of the rotifer Embata parasitica and the protozoan Epistylis in comparison with the invading species. These patterns may reflect host specificity by the parasites or may result from different susceptibilities of the native and invading host species. We consider the influence of parasitism on host invasions and resulting species distributions.