Food web structure in the high Arctic Canada Basin: evidence from δ13C and δ15N analysis

The food-web structure of the Arctic deep Canada Basin was investigated in summer 2002 using carbon and nitrogen stable isotope tracers. Overall food-web length of the range of organisms sampled occupied four trophic levels, based on 3.8 trophic level enrichment (¹⁵N range: 5.3–17.7). It was, thus, 0.5–1 trophic levels longer than food webs in both Arctic shelf and temperate deep-sea systems. The food sources, pelagic particulate organic matter (POM) (¹³C=–25.8, ¹⁵N=5.3) and ice POM (¹³C=–26.9, ¹⁵N=4.1), were not significantly different. Organisms of all habitats, ice-associated, pelagic and benthic, covered a large range of ¹⁵N values. In general, ice-associated crustaceans (¹⁵N range 4.6–12.4, mean 6.9) and pelagic species (¹⁵N range 5.9–16.5, mean 11.5) were depleted relative to benthic invertebrates (¹⁵N range 4.6–17.7, mean 13.2). The predominantly herbivorous and predatory sympagic and pelagic species constitute a shorter food chain that is based on fresh material produced in the water column. Many benthic invertebrates were deposit feeders, relying on largely refractory material. However, sufficient fresh phytodetritus appeared to arrive at the seafloor to support some benthic suspension and surface deposit feeders on a low trophic level (e.g., crinoids, cumaceans). The enriched signatures of benthic deposit feeders and predators may be a consequence of low primary production in the high Arctic and the subsequent high degree of reworking of organic material.     

比格犬MC4R基因多态性与体重相关性的研究

为了分析比格犬黑素皮质素受体-4基因多态性与犬体重的关系, 根据犬MC4R基因DNA外显子序列, 设计MC4R基因特异PCR引物1对, 犬DNA经PCR扩增, 克隆和测序, 寻找和确定犬MC4R基因的多态性位点, 分析多态性与犬体重的关系。结果在比格犬MC4R基因中发现2处单碱基缺失突变, 1个单碱基颠换变异, 存在Psh AⅠ酶切位点, 并基于PshAⅠ酶切位点建立了PCR-RFLP技术。统计分析显示犬MC4R基因型与体重显著相关, 可以考虑将MC4R基因作为犬体重的候选基因。     

MR 弥散加权成像对鉴别诊断良恶性椎体压缩性骨折的临床价值研究

目的：探讨MR弥散加权成像(DWI)鉴别诊断良恶性椎体压缩性骨折的临床价值。方法：对57 例经临床或病理证实的椎体 良恶性压缩性骨折患者行矢状位T1WI、T2WI、T2WI/FS 及DWI扫描,研究其在常规序列和DWI序列上的表现,将常规MR 序列 和DWI序列检出率进行比较,测量正常椎体及病变椎体的表观弥散系数(ADC)值,并进行统计学分析。结果：(1)MR 常规序列和 DWI序列(b=500s/mm2)表现：良性椎体压缩性骨折呈长T1 长或等T2 改变,T2WI/FS 呈高信号,DWI 可以呈高信号、等信号及低 信号;恶性椎体压缩性骨折呈长T1 长T2 信号,大部分病灶T2WI/FS 及DWI呈高信号,少数变现为低信号;(2)MR 常规序列和 DWI 序列(b=500s/mm2)病灶检出率的比较：T1WI、T2WI/FS 及DWI序列病灶检出率均高于T2WI 序列,其间的差别有显著性意 义(P<0.01),T1WI、T2WI/FS 及DWI序列病灶检出率之间无显著性差异(P>0.01);(3)ADC 值比较：在DWI(b=500 s/mm2)上,良性组 ADC 值为(2.03± 0.83)× 10-3mm2/s,恶性组ADC 值为(1.37 ± 0.75)× 10-3mm2/s,正常组ADC值为(0.36± 0.21)× 10-3mm2/s,成像条 件相同时,良性组高于恶性组,两组间有明显的统计学意义(P<0.05)。结论：DWI可较好的反映椎体的弥散特征,ADC值作为量化 指标可对良恶性椎体压缩性骨折进行可靠鉴别。     

新疆甘草化学成分研究

从新疆甘草(GlycyrrhizauralensisFisch.)根中分离得到5个化合物,分别鉴定为:槲皮素(1)、甘草次酸(2)、阿魏酸(3)、5,7,3′,4′-四羟基-7-葡萄糖基二氢黄酮醇(4)、8,5′-二羟基3′α-鼠李糖黄酮(5)。其中化合物4,5为首次从该植物中分离得到。     

高血压脑出血患者术后重症监护治疗与早期再出血的相关因素分析

目的:探究高血压脑出血患者术后重症监护治疗与早期(24 h内)再出血的相关因素。方法:回顾性分析2014年1月至2018年10月于中山大学附属第一医院及中山市人民医院行手术治疗并进行重症监护的高血压脑出血患者的相关资料,记录术后早期发生再出血情况,比较其相关因素,包括年龄、性别、术前格拉斯哥昏迷量表(GCS)评分、出血量、术前收缩压、术后收缩压、镇静时间、插管时间、有无使用止血药、血压波动、血压差、有无镇痛情况,分析术后早期再出血的影响因素。结果:本研究共纳入465例患者,其中术后早期再出血患者44例,未再出血患者421例,再出血发生率为9.46%(44/465)。高血压脑出血术后早期再出血患者的术后收缩压、有无镇痛、血压差、血压波动与未再出血患者比较差异具有统计学意义(P0.05)。术后早期再出血患者的年龄、性别及术前GCS评分、出血量、术前收缩压、镇静时间、插管时间、有无使用止血药与未再出血患者比较差异无统计学意义(P0.05)。多因素Logistic回归分析显示,患者血压波动大是术后早期再出血的危险因素,手术前后血压差大、术后使用镇痛治疗是其保护因素。结论:高血压脑出血患者术后血压波动、手术前后血压差及术后镇痛治疗均是早期再出血的影响因素,合理降压及镇痛治疗可减少脑出血术后早期再出血的发生。     

蒙药材刺柏叶中槲皮苷的含量测定

本实验建立了蒙药材刺柏叶中槲皮苷的HPLC含量测定方法.色谱条件为:Diamonsil C18(4.6 mm ×250 mm,5μm)和Shim-Pack C18(4.6 mm× 250 mm,5μm),流动相:甲醇-0.01 mol/L磷酸二氢钾溶液-冰醋酸(40∶ 60∶ 1.5),检测波长:254 nm,流速:1.0 mL/min,柱温:30℃.槲皮苷进样量在40.2 ng ～603.0 ng范围内线性关系良好(r =0.9998),其平均加样回收率为100.45％,RSD为0.69％(n=6).本方法简便易行,结果准确,重复性好,可用于刺柏叶中槲皮苷的含量测定.     

Variation in male reproductive traits among three bitterling fishes (Acheilognathinae: Cyprinidae) in relation to the mating system

Male traits that correlate with fertilization success include testis size and structure, ejaculate size, ejaculation frequency, and sperm motility. Two hypotheses potentially explain interspecific differences in these traits: sperm competition and sperm limitation. We examined variation in six traits associated with fertilization success in three closely‐related species of bitterling fish; the European bitterling (Rhodeus amarus), the Chinese rose bitterling (Rhodeus ocellatus), and the Chinese bitterling (Rhodeus sinensis). Interspecific differences indicated that the three study species have evolved different sperm allocation strategies. Rhodeus amarus displayed the most developed reproductive apparatus with a number of traits associated with both high levels of sperm production and fertilization efficiency. Rhodeus ocellatus and R. sinensis appear to have more comparable sperm allocation strategies, although relative testis size and spermatozoa head : tail ratio were greater in R. sinensis, suggesting that sperm competition risk may be higher in this species. All three species possessed an unusually well developed sperm duct with evidence of mucin production, which greatly extends the longevity of sperm and, consequently, the period over which fertilization can occur. We discuss these findings in the context of differences in the mating systems of the species examined, and relate the results obtained to differences in the temporal and spatial clustering of fertilizations. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 622–632.     

The impact of tree modification by African elephant (Loxodonta africana) on herpetofaunal species richness in northern Tanzania

In Africa, no other nonhuman animal fulfils the role of ecosystem engineers to the extent of the elephant. However, little is known about the relationship between elephant modified habitats and species composition of other animals. Our objective was to sample the herpetofauna within an Acacia habitat that varied in the degree of elephant impact. If elephant foraging was only modifying but not degrading or enriching the habitat, then herpetofauna species abundance and richness were predicted to be similar in elephant damaged and elephant excluded areas. We conducted this study at Endarakwai Ranch in northeastern Tanzania for 6 months in 2007 and 2008. We sampled herpetofaunal species richness and abundance within high, medium and low elephant damaged areas and in a plot that excluded elephants. Areas of heavy damage yielded higher species richness than the exclusion plot. Species diversity did not differ between the damaged areas and the exclusion plot. Frogs were more abundant in areas of high damage; in contrast, toads were found the least in high damage areas. The results support the notion that free ranging elephants influence herpetofaunal species distribution by creating habitat complexity through modifying the woodland area.     

应用Maxent生态位模型预测淡水钩虾(甲壳纲,端足目)的分布(英文)

预测物种的适生区对于物种资源的评估、保护以及生物多样性的管理非常重要。由于全球气候变化和人类的过度开发,冷水性无脊椎动物的衰减速度比在陆地和海洋生活的无脊椎动物都要高。目前关于中国淡水钩虾分布方面的研究很少,本研究基于103个地表淡水钩虾的不同分布位点和广布种湖泊钩虾Gammarus lacustris 23个不同分布位点以及32个环境因子数据,使用生态位模型(Maxent)预测了淡水钩虾和湖泊钩虾在我国的适生分布区域。结果显示淡水钩虾非常适合分布在我国的一些偏远山区,如长白山、太行山、横断山、天山、昆仑山和祁连山,而青藏高原的东部、西部边缘地区和南部分布地区、尼泊尔、不丹和朝鲜半岛也是淡水钩虾的潜在适生区域,但淡水钩虾在我国华南、华中和华北的平原地区分布却很少,其在我国的潜在分布区与-10℃和5℃1月平均气温线间的区域相似。淡水钩虾是典型的狭温性物种,在不适宜温度条件下很难存活,这可能也是限制其扩散和存活的关键性因素。     

血管抑素的临床应用研究进展

血管抑素是第一个被发现的肿瘤源性血管生成抑制因子,能抑制血管内细胞的增殖和迁移,从而抑制肿瘤的生长。通过一些实验方法能够检测肿瘤患者体内的血管抑素水平。血管抑素在未来的肿瘤治疗、诊断、预后判断和新生血管疾病的治疗中有着广阔的应用前景。