Nucleic acids and proteins such biological molecules life is the material base, the origin of life key lies in the origin of these life substances, i.e. the original in no life on the earth because of natural causes, and through inanimate matter produce various chemical action, organic matter and biological molecules. Therefore, the origin of life problem is first primitive of the origin and early evolution of organic matter. The role of chemical evolution is a kind of chemical materials, these chemical material composition amino acids, sugar etc universal "structural unit", nucleic acids and proteins such life from this knot "material is the combination of structural element". In 1922, biochemists Mr Bahrain's first proposed can be used to verify that the hypothesis, the original earth in some of the inorganic, from lightning, sunlight, under the action of the energy into the first batch of organic molecules. After the 1953 after 31 years, American chemist miller's first test card in bahrain that hypothesis. He die like original earth with atmospheric composition, hydrogen, methane and ammonia and water vapor, through the heating and spark discharge, synthetic organic molecular amino acids. Following the miller, many through simulation experiment of original earth conditions. And the other for the synthesis of the important biological organisms molecules, such as DNA and its set, adenine, deoxyribose nucleoside and nucleotide,, fatty acid, porphyrins and lipid, etc. In 1965 and 1981, our country and in the world's first synthetic insulin and yeast alanine transfer RNA. Protein and nucleic acid is formed by the turning point to a lifeless life. The above two kinds of biological molecules of synthetic success, started by artificial synthetic life substances to study the new era of the origin of life. Generally speaking, life chemical evolution process including four stages: small molecules generated from inorganic small organic molecules; Small organic molecules from formation organic macromolecular; From organic macromolecular composition can sustain itself the stability and development of many molecular system; Evolution of molecular system from more primitive life.
核酸和蛋白质等生物分子是生命的物质基础，生命的起源关键就在于这些生命物质的起源，即在没有生命的原始地球上，由于自然的原因，非生命物质通过化学作用，产生出多种有机物和生物分子。因此，生命起源问题首先是原始有机物的起源与早期演化。化学进化的作用是造就一类化学材料，这些化学材料构成氨基酸，糖等通用的“结构单元”，核酸和蛋白质等生命物质就来自这结“结构单元”的组合。 1922年，生物化学家奥巴林第一个提出了一种可以验证的假说，认为原始地球上的某些无机物，在来自闪电，太阳光的能量的作用下，变成了第一批有机分子。时隔31年之后的1953年，美国化学家米勒首次实验证了奥巴林的这一假说。他模似原始地球上的大气成分，用氢、甲烷、氨和水蒸气等，通过加热和火花放电，合成了有机分子氨基酸。继米勒之后，许多通过模拟原始地球条件的实验。又合成出了其他组成生命体的重要的生物分子，如嘌呤、嘧定、核糖、脱氧核糖、核苷、核苷酸、脂肪酸、卟啉和脂质等。1965年和1981年，我国又在世界上首次人工合成胰岛素和酵母丙氨酸转移核糖核酸。蛋白质和核酸的形成是由无生命到有生命的转折点。上述两种生物分子的人工合成成功，开始了通过人工合成生命物质去研究生命起源的新时代。一般说来，生命的化学进化过程包括四个阶段：从无机小分子生成有机小分子；从有机小分子形成有机大分子；从有机大分子组成能自我维持稳定和发展的多分子体系；从多分子体系演变为原始生命。
脱氧戊糖核酸的分子结构
脱氧戊糖核糖生物学性质提示它的分子结构很复杂，但是这里的描述X光衍射研究表明它的基本分子结构很简单。这次交流的目的是为了初步的描述一些关于在自然状态下多核糖链结构如何以螺旋并以此方式存在的方法的实验证据。一段时间之后，关于这项工作的全面描述将会发表。
脱氧核糖核酸的结构在所有的物种中都是相同的（虽然他们的N碱基对的比例有很大的不同），包括在细胞中或者是提取的核蛋白，和纯化的核酸中。多核酸链的线性组堆积成了平行的或者类晶体的结构。在所有的试验中，X光衍射图片包括两个部分，其中一部分由沿链均匀空间间隔排列决定，另外一个则取决于整个链的空间构象中的更长空间间隔排布。不同N碱基对的排列是看不见的。
定向类晶体脱氧核糖核酸（在下面的交流被franklin 和gosling 称为结构B)给出了纤维的图像（显示于图像1中）ASTBURY认为3.4-4中的反折与与沿纤维轴方向排列的核糖与沿纤维轴方向排列的核糖相一致。但是34A中的层次线不是因为多核糖排列造成的，而是与链的空间排列所决定的，因为核糖链要比间质水密度大的多，这样将会出现强的衍射。在经络线没有反折表明它是一个与纤维长相平行的螺旋结构
图像1.脱氧核糖核酸的显微图像，来自B.coli
Acta Biologica Hungarica
2014-12-01
Regulation of auxin, abscisic acid
and salicylic acid levels by ascorbate application under heat stress in
sensitive and tolerant maize leaves.
Burcu Seckin Dinler, Emel Demir, Yasemin Ozdener Kompe
PMID
25475985
Abstract
In the present study, the effect of
ascorbic acid (5 mM) on some physiological parameters and three hormones
(auxin, abscisic acid, salicylic acid) was determined under heat stress
(40 °C) in maize tolerant cv. (MAY 69) and sensitive cv. SHEMAL (SH) at
0 h, 4 h and 8 h. Heat stress reduced total chlorophyll content (CHL),
relative water content (RWC) and stomatal conductance (gs) in SH but did
not lead to changes in MAY 69 at 4 h and 8 h. However, pretreatment
with ascorbic acid increased (CHL), (RWC) and (gs) in SH under heat
stress while it reduced MDA content significantly in both cv. We also
observed that heat stress led to a reduction in SA level but increased
ABA and IAA levels in SH, whereas it increased SA and IAA levels but did
not change ABA level in MAY 69 at 4 h. Furthermore, in SH, ASC
application under heat stress increased SA level and decreased IAA and
ABA levels at 4 h, but it had no effect on SA and ABA at 8 h.
On the other hand, rainbow trout and brown trout appear more resistant to fluoride than freshwater benthic macroinvertebrates. Camargo and Tarazona (1990) have estimated 96 hour LCs0 values in soft water of 26.3,26.5, 38.5, 48.2 and 44.9 ppm F- for Hydropsyche bulbifera, H. exocellata, H. pellucidula, H. lobata and Chimarra marginata larvae, respectively. This lower sensitivity of trout species to fluoride could be explained because fluoride ions may form stable complexes with calcium in blood and bone of fish (Sigler and Neuhold,1972), whereas stable complexes could not be formed in freshwater insect larvae. However, marine invertebrates exposed to fluoride compounds tend to accumulate fluoride in their exoskeleton during chronic exposures (Wright and Davidson, 1975).
另一方面，虹鳟鱼和褐鳟比海底大型无脊椎动物抵抗氟化物的能力似乎更强。Camargo和Tarazona估计，在软水中的F离子浓度对Hydropsyche的这四个种的幼体的96小时的LCs0值分别为26.3，26.5，38.5，48.2。这里显示这些鳟鱼对氟化物的敏感性较低，原因可以解释为负离子可能在血液里和在骨骼里形成稳定的复合物，然而这种稳定的复合物在淡水昆虫幼虫里不能形成。不过，在长期暴露在氟化物的情况下，海洋无脊椎动物趋向于在外骨骼积累氟化物。
Maximum safe criteria of fluoride ion for fish in natural ecosystems have not yet been determined (USEPA,1986) because a range of widely LCs0 values has been reported (Smith et al., 1985). However, it is evident that freshwater fish may resist higher fluoride concentrations in hard water than in soft water (Herbert and Shurben,1964; Sigler and Neuhold, 1972; Pimentel and Bulkley, 1983; Smith et al., 1985). In this connection, Pimentel and Bulkley (1983) have suggested that a reservoir of calcium in the water surrounding fish tends to compensate for the loss of calcium and thereby delays toxic effects of fluoride on the organisms.
在自然生态系统中对鱼的氟化物浓度的最高安全标准尚未确定，因为报道的LCs0值跨越很大的范围。然而，有一点是肯定的：淡水鱼在硬水中比在软水中的氟化物抵抗能力更强。基于这个关系，Pimentel和Bulkley提出在鱼周围的水里的钙补偿了钙的流失，因此延迟了氟化物对生物体的影响。
Studies on fluoride toxicity to freshwater fish should be conducted in water quality conditions of highest toxicity(e.g., soft water) for determining safe criteria of fluoride ion for fish, and chronic toxicity bioassays should be performed to improve these fluoride quality criteria. In this sense, the
data offered in this paper may provide a suitable background for future long-term toxicity studies.
氟化物对淡水鱼的毒性研究应该在最高毒性环境下进行以便确定氟化物对鱼的安全标准，然后用慢性毒性的生物检定来改良这些氟化物的质量标准。从这个意义上讲，本论文提供的数据为将来的长期毒性研究提供了一个很好的背景。
ACKNOWLEDGEMENTS
The authors thank the Department of Animal Health (CIT-INIA) for its logistical support during laboratory studies. Funds for this toxicological research were provided by a grant from the National Institute of Agrarian Researches in Spain.
鸣谢：作者感谢动物健康中心在实验室研究阶段提供的后勤支持。本毒理研究实验的基金由西班牙国家土地研究所授予。
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