"罪魁祸首"小龙虾?

说起小龙虾,堪称夜宵(尤其夏季)界的扛把子!什么毛豆、花生简直弱爆了!论口味选择,都不带重样的!十三香、蒜香、香辣、麻辣、油焖、椒盐、黑椒……只有你想不到,没有做不到!所谓"虾红"是非多,有一则新闻:"女子健身后与朋友吃了6斤小龙虾,凌晨入院!3天后还痛到睡不着",这个内容不禁让人想起江湖中关于小龙虾的各种传闻!     

"脚气"是"脚气病"吗?

问 :“脚气”是“脚气病”吗 ?答 :足癣俗称“脚气”。“脚气”是因霉菌感染足部而引起的一种传染性皮肤病 ,多见于成年人 ,病程缓慢 ,有不同程度的搔痒。“脚气”的发生部位多在足趾缝或足底 ,这是由于趾间缝隙小 ,汗液蒸发较差 ,适于霉菌的繁殖。主要有水疱型、鳞屑型、趾间糜烂型和增厚型 4种类型。“脚气病”是人体缺乏维生素 B1而起的一种疾病。主要症状是四肢无力 ,肌肉疼痛萎缩 ,皮肤逐渐失去感觉 ,麻痹和麻木 ,从脚部开始向心脏发展 ,心脏扩大 ,呼吸困难严重者甚至死亡。所以 ,“脚气”与“脚气病”是两种不同的疾病。“脚气”是“…     

"绿色革命"基因是何方神圣?

经过50多年的研究,科学家们发现,小分子化合物赤霉素有着步骤繁琐的生物合成过程、错综复杂的信号传导过程和代谢调控过程.通过广泛搜集矮秆、半矮秆突变体,并在模式植物拟南芥以及水稻、小麦等作物中进行深入的生物学功能解析和分子特性研究,科学家们发现了赤霉素的生物合成、信号传导以及代谢调控相关基因的突变都会影响植物株高.那么,...     

罗马军团"落叶"甘肃?

千年悬案论争未果公元前53年,一支罗马军团的部队在卡尔莱战败,部分将士突围后不知所终,成为一桩千年历史悬案。不少中外学者认为,这支战败的罗马军队残部最终来到了中国,西汉政府为了安置他们,在今甘肃永昌境内设立骊县,他们的后裔如今还在永昌繁衍生息。另一些学者则考证认为,骊县为罗马人而建的说法不能成立。骊县到底是不是为安置罗马军团残部而建?最近,兰州大学的科研人员从永昌县91名志愿者身上采集来全血样本,试图通过DNA技术,寻找到这一问题的答案。     

Does "afternoon diabetes" predict diabetes?

Twenty-eight men were given morning and afternoon oral glucose tolerance tests in 1969 and again in 1975. According to British Diabetic Association criteria all 28 had normal morning values in 1969 but seven had "afternoon diabetes". Four men had diabetic values in the morning in 1975 but only two of these had had afternoon diabetes in 1969. Better prediction of subsequent diabetes was obtained by calculating the area under the morning glucose tolerance curve in 1969. All four men who progressed to diabetes had areas exceeding 1000 units, which distinguished them absolutely from the other 24. They also tended to be more obese, but this was less predictive of subsequent diabetes.     

"降龙木"到底是何方神圣?

"大爷,前面庄上那棵大树是什么树啊?" "哎呀,小伙子,相传这棵树可厉害了!它叫降龙木,全世界就只有这么一棵了,当年穆桂英大破天门阵用的就是这种木头……" 为了一睹"降龙木"的风采,我们特地驱车来到济南市历城区彩石街道捎近村.为什么叫这个奇怪的名字呢?据说在古代,章丘百姓去泰山上香会经此处,因为这样比走大路会稍近些,也...     

What is "epi" about epigenetics?

What counts as epigenetic depends on what counts as genetic. It is argued that Weismannism, the doctrine of genetic continuity and somatic discontinuity, is the basis for an overly inclusive concept of epigenetics as every inherited resource < beyond the genes >. An alternative theoretical perspective, the < reproducer > concept, facilitates analysis of multiple inheritance systems without labeling all non-genetic inheritance < epigenetic >.     

Are all "cytoprotective" drugs gastroprotective?

The effect of three--structurally different--groups of compounds was compared against gastric mucosal damages induced by ethanol or prostaglandin (PG) synthesis inhibitors, as well as against carrageenan-induced inflammation. All the compounds studied--SH-compounds (cysteamine, 2,3-dimercaptosuccinic acid, D,L-penicillamine), SH-blocking N-ethylmaleimide (NEM) and morphine-exerted dose-dependent inhibition on carrageenan edema test and against ethanol-induced gastric damage. Mucosal lesions induced by PG synthesis inhibitors (indomethacin 20 mg/kg, naproxen 75 mg/kg, piroxicam 60 mg/kg) were inhibited by drugs studied when the compounds were given before the damaging agents. However, when the drugs were injected 1 h after the inhibitors of PG synthesis opposite actions were observed; SH-compounds exerted protective, while NEM (2 mg/kg p.o.) and morphine (5 mg/kg p.o.) aggravating action. The results suggest that: 1. SH-compounds might have therapeutic importance in the treatment of gastric damage induced by prostaglandin synthesis inhibitors. 2. Reconsideration of the use of the term "cytoprotection" is necessary, since "cytoprotective" agents may aggravate mucosal damage in other ulcer model.     

Are membrane proteins "inside-out" proteins?

One of the central paradigms of structural biology is that membrane proteins are "inside-out" proteins, in that they have a core of polar residues surrounded by apolar residues. This is the reverse of the characteristics found in water-soluble proteins. We have decided to test this paradigm, now that sufficient numbers of transmembrane alpha-helical structures are accessible to statistical analysis. We have analyzed the correlation between accessibility and hydrophobicity of both individual residues and complete helices. Our analyses reveal that hydrophobicity of residues in a transmembrane helical bundle does not correlate with any preferred location and that the hydrophilic vector of a helix is a poor indicator of the solvent exposed face of a helix. Neither polar nor hydrophobic residues show any bias for the exterior or the interior of a transmembrane domain. As a control, analysis of water-soluble helical bundles performed in a similar manner has yielded clear correlations between hydrophobicity and accessibility. We therefore conclude that, based on the data set used, membrane proteins as "inside-out" proteins is an unfounded notion, suggesting that packing of alpha-helices in membranes is better understood by maximization of van der Waal's forces, rather than by a general segregation of hydrophobicities driven by lipid exclusion.     

How "Molecular Ecology" Should be Defined?

Ｈｏｗ　“Ｍｏｌｅｃｕｌａｒ　Ｅｃｏｌｏｇｙ”　Ｓｈｏｕｌｄ　ｂｅ　Ｄｅｆｉｎｅｄ？Ｃｈｉｎ－ｍｉｎＨｓｉａｎｇ；Ｌｉａｎ－ＢｉｎＸｉａｎｇ；ａｎｄＪｉａ－ＮｉｎｇＸｉｎｇＣｈｉｎ－ｍｉｎＨｓｉａｎｇｉｓｉｎｔｈｅＶｉｒｕｓＲｅｓｅａｒｃｈｌｎｓｉｔ...     

泡桐长"笼"了是怎么回事?

泡桐 Paulownia tomentosa Steud是我国北方常见的速生绿化行道树和材木。在生活中常会见到有些泡桐的个别枝条上腋芽和不定芽大量萌发 ,丛生许多细弱小枝 ,节间变短 ,叶序紊乱 ,叶片小、黄、薄且皱缩 ,小枝上又发出许多更小的枝 ,重复数次 ,至秋天常簇生成团 ,小枝愈来愈细弱 ,叶片愈来愈小 ,远观似大小不一的鸟巢 ,俗称泡桐长“笼”了。严重时花的柱头或花柄亦变为小枝 ,小枝上又生小枝 ,整个花器都呈丛枝状。冬季落叶后 ,小枝枯死 ,次年又发出更多的小枝 ,根部有时也发生坏死的现象。胸径 15cm的泡桐发病后 ,4～5年内即会枯死 ,大树则会…     

"Simulated molecular evolution" or computer-generated artifacts?

1. The authors define a function with value 1 for the positive examples and 0 for the negative ones. They fit a continuous function but do not deal at all with the error margin of the fit, which is almost as large as the function values they compute. 2. The term "quality" for the value of the fitted function gives the impression that some biological significance is associated with values of the fitted function strictly between 0 and 1, but there is no justification for this kind of interpretation and finding the point where the fit achieves its maximum does not make sense. 3. By neglecting the error margin the authors try to optimize the fitted function using differences in the second, third, fourth, and even fifth decimal place which have no statistical significance. 4. Even if such a fit could profit from more data points, the authors should first prove that the region of interest has some kind of smoothness, that is, that a continuous fit makes any sense at all. 5. "Simulated molecular evolution" is a misnomer. We are dealing here with random search. Since the margin of error is so large, the fitted function does not provide statistically significant information about the points in search space where strings with cleavage sites could be found. This implies that the method is a highly unreliable stochastic search in the space of strings, even if the neural network is capable of learning some simple correlations. 6. Classical statistical methods are for these kind of problems with so few data points clearly superior to the neural networks used as a "black box" by the authors, which in the way they are structured provide a model with an error margin as large as the numbers being computed.7. And finally, even if someone would provide us with a function which separates strings with cleavage sites from strings without them perfectly, so-called simulated molecular evolution would not be better than random selection.Since a perfect fit would only produce exactly ones or zeros,starting a search in a region of space where all strings in the neighborhood get the value zero would not provide any kind of directional information for new iterations. We would just skip from one point to the other in a typical random walk manner.     

Science:"记忆碎片"是真的吗?

正半个多世纪以来,神经学家们一直以为长期记忆是由于多个短期记忆储存起来形成的。而最近一项对记忆形成的神经回路的研究则表明这一说法有可能是错的,因为两种类型的记忆(长期与短期)能够同时产生。这项研究是由来自MIT的研究者们做出。他们参考了此前标记特殊"记忆"细胞的手段,并更进一步地强制性使小鼠对特定的记忆作出反应,并且断开了长期与短期记忆的连接。