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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The 3 ́ terminus of tyrosine tRNA gives the T1 ribonuclease product AAUCCUUCCCCCACCACCAOH. This is absent in digests of precursor tRNA but the entire sequence is present in nucleotide 7 occupying a different position on the fingerprint (Fig. 1). Nucleotide 7 contains the 3 ́ terminus of the tRNA with three additional n... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The 5 ́ terminus of tyrosine tRNA is pGGU—which gives pGp with T1 ribonuclease and pGGU with pancreatic ribonuclease. Both of these products are absent from digests of precursor. The additional pancreatic ribonuclease product GGU is the only sequence which could contain the 5 ́ terminus of the tRNA itself, suggesting t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 2. Possible configuration for tyrosine precursor. The hydrogen-bonded loops shown are stable according to the approximate criteria cited in ref. 20. The arrows pointing towards the sequence indicate the beginning of the 5 ́ end of the tRNA moiety and a cleavage point. In the mature tRNA, none of the last four nucl... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 32P pulse-label experiments. 中文
The T1 ribonuclease fingerprint of precursor from cells infected with φ80 psu A2 U80 U41 P showed the altered products resulting from the three mutations in the tRNA portion of the precursor; A2 gives AUG instead of UG; U80 gives a 3 ́ terminus product with altered mobility; U41 changes ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | resuspended in 35 μl. 40% sucrose made 0.04 M in EDTA, and containing 2 μl. of a saturated bromphenol blue solution, and was then layered on a 10% acrylamide gel. Electrophoresis was for approximately 16 h at 400 V and 4°C. In separate experiments we have observed that mature tRNA marker runs in the same position as ba... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Band C contains the extreme 5 ́ end of the precursor molecule reading in to the sequence...AGGCC(A). Presumably the rest of the precursor sequence at this end of the molecule has been degraded to mononucleotides. 中文
Precursor exposed to cell extract (band A in Fig. 3), but still retaining its original mobility in gels ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Although we have studied the precursor transcribed from a tRNA inserted in a phage chromosome, transcription is likely to be the same when the gene is on the bacterial chromosome. In particular, the tRNA gene on the phage chromosome still responds to relaxed-stringent control as do other bacterial tRNAs in φ80 infected... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | (Fig. 2) and may also effect “precursor-endonuclease” binding in an undetermined fashion such that breakdown of precursor to products other than tRNA is enhanced. The phenotype of other mutants (A15, A25, A17 and A 31) distant from the cleavage point in the molecule suggests that a structural factor is also important i... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | It should be noted that precursor we isolate is susceptible to precursor endonuclease attack in vitro suggesting, according to our model, that if it accumulates as structure I in vivo, it can rapidly assume structure II in vitro. Furthermore, to explain the low level of mature tRNA produced by these mutants, it is nece... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Abelson, J. N., Gefter, M. L., Barnett, L., Landy, A., Russell, R. L., and Smith, J. D., J. Mol. Biol., 47, 15 (1970).
Brownlee, G. G., and Sanger, F., Europ. J. Biochem., 11, 395 (1969).
Abrell, J. W., Kaufman, E. E., and Lipsett, M. N., J. Biol. Chem., 246, 294 (1971).
Bartz, J. K., Kline, L. K., and Söll, D., Bioche... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
图1是A25 tRNA前体的T1核糖核酸酶和胰核糖核酸酶指纹图。未标记的核苷酸与那些在成熟tRNA酶解物中发现的核苷酸一致,有数字编号的核苷酸是由tRNA前体的额外片段产生的。表1给出了相应核苷酸的序列。前体中tRNA部分的所有核苷酸都用以前描述过的酶解或碱溶法进行了鉴定[8]。分析结果表明前体具有完整的初级tRNA序列。但与成熟tRNA相比,有以下两点重要的不同:(1)那些通常情况下被修饰的碱基几乎完全未被修饰;(2)源于成熟tRNA 5′和3′末端的T1核糖核酸酶和胰核糖核酸酶酶解产物在前体的酶解物中不存在。 英文
表1.tRNA前体酶解的额外产物
除非特别标注,所有产物的产量均以摩尔为单位。这些序列均源于T1核糖核酸酶... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 通过鉴别pppGp和pppGC可以确定前体的5′末端,而且我们断定此末端的初期转录本是完整的。 英文
通过对T1核糖核酸酶部分酶解的产物进行分析确定5′端片段的序列[8,12],结果如图2所示。对含有tRNA部分的T1核糖核酸酶的部分酶解产物进行检测,结果发现它们与从酪氨酸tRNA的类似酶解物中分离出来的片段完全一致[8]。这表明前体分子中tRNA部分的二级结构与成熟tRNA中的类似。假设tRNA部分具有三叶草形二级结构,并且与5′端的序列不发生相互作用,则后者可能的二级结构如结构II所示(图2)。 英文
图2.酪氨酸前体的可能结构。根据参考文献20中的大概标准,图中氢键环是稳定的。指向序列的箭头表示tRNA组分5′端的起始点,同... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 除了源于3′末端的两个点以外,B条带的T1核糖核酸酶酶解物的指纹图(图4)也与成熟A25 tRNA的指纹图相同。其中一个点的迁移率与前体3′端寡核苷酸的迁移率相同。而另一个点,在指纹图上该点的附近,呈现出大约20%的产量,并且至少缺失了两个终端核苷酸,我们猜测是因为细胞提取液中其他核酸酶的作用所致。修饰的3′端的产量依反应混合物的孵育时间而定。延长电泳时间能使B条带分解成两个条带,迁移较快的条带仅含有修饰的3′端。 英文
图4.A25前体切割产物T1核糖核酸酶酶解物的二维电泳分离放射自显影图。从凝胶中洗脱出图3中的B条带,然后用T1核糖核酸酶进行酶解,最后用二维电泳法分离产物。放射自显影图中显示出了新产生的5′端以及前体3′端寡核... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 在以上两种模型中,前体的二级结构和一级结构一样,都可能对确定tRNA生物合成的动力学起着重要作用。 英文
需要注意的是:根据我们的模型,我们分离出的前体在体外很容易受到前体内切酶的攻击这一点表明,如果前体以结构I的形式在体内积累,那么在体外它就会快速转换为结构II的形式。此外,为了解释由这些突变体产生的成熟tRNA产量低的原因,还需要假设在体内存在着另外一条降解而非生成tRNA的途径。 英文
我们用只携带一个tRNA基因的φ80噬菌体进行实验,得到了tRNA前体的第一个序列分析结果。关于大肠杆菌中T4诱导的tRNA的类似数据(麦克莱恩,个人交流)也将被报道。到目前为止还没有直接的证据能证明大肠杆菌染色体中tRNA的转录本质。 英文
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Milligram quantities of the haemoglobin mRNA were prepared using procedures described previously4,5 except that RNAs were separated by zonal rotor. The mRNA is well resolved from the other RNAs and gives a single band in acrylamide gel electrophoresis. 中文
The 3 ́ terminal nucleoside of the RNA was labelled using the pe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Tris (pH 7.6). Elution was carried out using a 3 litre gradient of 0.0–0.45 M NaCl in Tris (pH 7.6) and 7 M urea. The column was stripped with a 100 ml. gradient of 0.45–1.0 NaCl in the same buffer. Samples of 3 ml. of each fraction with 1 ml. H2O were counted in 10 ml. of “Insta-Gel” (Packard) at approximately 12% eff... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The T1 fragment elutes in the region of eight phosphate groups inferring that it comprises nine bases as the terminal fragment lacks the phosphate on the 3 ́ terminus, but this is only tentative as base composition begins to influence the elution pattern of longer oligonucleotides6,10. The first guanosine nucleotide wo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | fragments at pH 3.0 suggested to Hunt and Laycock that the 3 ́ terminal fragments might be enriched in adenylic acid11. 中文
The fragments from both RNAase digests occur in a 2:1 ratio with the smaller one predominating. This would not be anticipated if each fragment originated from a different globin chain mRNA; indeed,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Enzymatic digestion at different enzyme substrate ratios (1:100 and 1:20) for different times (30 min and 16 h) revealed no differences in elution patterns. Acrylamide gel electrophoresis of the mRNA used in this study showed no contamination by any of the intact ribosomal RNAs. 中文
Consequently, we feel that these resu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Lim and Canellakis have isolated an A-rich fragment approximately fifty to seventy bases long (70% A) from the purified rabbit globin mRNA fraction26. Our calculations of the maximum percentage of A which could be present in a fragment of this size, if it were derived from within the globin coding region, indicate that... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | An alternative interpretation of our results has as its basis the idea that different proteins have emerged during evolution through gene duplication, followed by independent mutation of each gene30. Ingram31 used this idea to explain the remarkable similarity of the different globin chains. This would produce identica... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | DeWachter, R., and Fiers, W., J. Mol. Biol., 30, 507 (1967).
RajBhandary, U. L., J. Biol. Chem., 243, 556 (1968).
Glitz, D. G., and Sigman, D. S., Biochemistry, 9, 3433 (1970).
Glitz, D. G., Bradley, A., and Fraenkel-Conrat, H., Biochim. Biophys. Acta, 161, 1 (1968).
Robinson, W. E., Tessman, I., and Gilham, P. T., Bio... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Ingram, V. B., Nature, 189, 704 (1961).
DeWachter, R., Vanbenberghe, A., Merregaert, J., Contreras, R., and Fiers, W., Proc. US Nat. Acad. Sci., 68, 585 (1971).
Cory, S., Spahr, P. F., and Adams, J. M., Cold Spring Harbor Symp. Quant. Biol., 35, 1 (1970).
Sanger, F., Brownlee, G. G., and Barrell, B. G., J. Mol. Biol., ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 将RNA溶解于1 ml 0.01 M的磷酸钠缓冲液(pH值为6.0)中,再加入0.05 ml 0.1 M NaIO4,在黑暗中静置1 h,然后加入0.05 ml 1 M的乙二醇并静置30 min。接下来,加入1 ml 0.5 M的磷酸钠缓冲液(pH值为7.0)并混合均匀。将NaB3H4(502 mCi/mM,安玛西亚–瑟尔公司,结晶固体)溶解于冷的1 N NaOH中,这样每0.1 ml含有10 mCi;这就是常规情况下使用的放射性水平。还原反应在室温下持续进行2 h。用冷乙醇沉淀RNA 2到3次,然后按照下述方法从过量的3H中进一步提纯:在斯平科SW-27离心机中,通过1到2个5%~20%(重量比)蔗糖浓度梯度在2°C条件下离心24... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
因此我们认为,这些结果真实地反映了球蛋白mRNA组分的分子组成,并认为两种球蛋白mRNA都终止于多聚腺苷酸区域,该多聚腺苷酸区域与两种球蛋白链上的已知氨基酸序列都不相关。这些结果与UAA链终止三联体的存在相符合。 英文
末端片段和球蛋白合成
每一个末端片段都源自于一个mRNA。兔网状细胞中的α链库[15-17]以及新生α链在较小的多聚核糖体上出现的发现[18]都与α链mRNA的过量相一致。因此,较小片段可能源于α链mRNA而较大片段源于β链mRNA的推断似乎是合理的。然而,亨特和他的同事们曾发现,α链的合成实际上更快一些[19],而且目前的数据没有将α链mRNA或β链mRNA与两个片段中的任何一个对应起来。两种球蛋白mRNA也... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
(邓铭瑞 翻译;李素霞 审稿)
On the Mechanism of Action of lac Repressor
B. Chen et al.
Editor’s Note
The E. coli lac operon is a set of genes responsible for the breakdown of lactose into sugars used for metabolism. In the cell’s default state, a repressor molecule prevents gene expression by binding to a control region of bac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | however, also alters the operon so that the polymerase and repressor compete for binding. 中文
Wild Type lac DNA
When λh80dlac DNA containing a normal lac promoter is preincubated with CRP and RNA polymerase in the presence of cyclic AMP, a complex is formed which is resistant to inhibition by rifampicin. In the presence... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | repressor bind independently. 中文
Table 1. Repressor Action with λh80dlac DNA
Each reaction mixture of 0.15 ml. contained 0.02 M Tris-HCl, pH 7.9, 0.01 M MgCl2, 0.06 M KCl, 1×10–4 M dithiothreitol, 4.6 μg λh80dlac DNA, 0.75 μg rho, 1×10–4 M cyclic AMP, 1.2 μg repressor, 1.7 μg CRP, 3.6 μg RNA polymerase (350 U/mg), 0.1... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | We described a mutation of the lac operon, ps, which results in increased synthesis of β-galactosidase both in vivo and in vitro6. DNA containing the lac ps mutation serves as a better template for lac RNA synthesis in a purified in vitro system than the parental lac DNA3. As some single mutations in the lac operon aff... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Although the addition of IPTG and rifampicin does not restore lac transcription to unrepressed levels, prolonged incubation with inducer before addition of rifampicin does (Fig. 1). RNA polymerase was added to a repressor–DNA complex in the presence of CRP and cyclic AMP. After 5 min of incubation, IPTG was added and t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | measured the binding of repressor to radioactively labelled lac DNA. 中文
Fig. 2. Stability of preinitiation complex. The experiments were performed as described in Table 1. ○, CRP and polymerase added before repressor; ●, repressor added before CRP and polymerase; □, control, no repressor added.
中文
CRP has an affinit... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | of the preinitiation complex, and transcription from preinitiation complexes already formed in the absence of repressor is partially inhibited by the subsequent addition of repressor. 中文
Fig. 3. Mechanism of action of lac repressor. RNA polymerase is represented by solid bar and lac repressor by striped bar. a, Normal... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Our findings, in agreement with previous genetic studies, suggest that the promoter and operator binding sites may overlap in the lac ps mutant. Ordal13 finds that some virulent (oc) mutants map on each side of a promoter mutant in the x region of λ. Smith and Sadler (personal communication), who have studied a large n... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | competition by invoking two promoter sites. It also supposes that a cyclic AMP–CRP-dependent promoter has been translocated close to the lac operator or that a mutation can create a new promoter in a very small region of the lac operon which is still repressible by lac repressor and still cyclic AMP–CRP-dependent. No e... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Hayward, W. S., and Green, M. H., Proc. US Nat. Acad. Sci., 64, 962 (1969).
Wu, A., Ghosh, S., and Echols, H., Fed. Proc., 30, 1529 (1971).
Chadwick, P., Pirrotta, V., Steinberg, R., Hopkins, N., and Ptashne, M., Cold Spring Harbor Symp. Quant. Biol., 35, 283 (1970).
Ordal, G., in The Bacteriophage Lambda (edit. by the... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
表1.阻遏物与λh80d乳糖操纵子DNA的作用
每0.15 ml反应混合物包含:pH值为7.9的0.02 M Tris-HCl,0.01 M氯化镁,0.06 M氯化钾,1×10–4 M二硫苏糖醇,4.6 μg λh80d乳糖操纵子DNA,0.75 μg rho,1×10–4 M环AMP,1.2 μg阻遏物,1.7 μg CRP,3.6 μg RNA聚合酶(三磷酸胞苷,350 U/mg),ATP(三磷酸腺苷)、GTP(三磷酸鸟苷)、UTP(三磷酸尿苷)各0.15 mM以及0.075 mM CTP(20 Ci/mmol)。将DNA、环AMP和基础盐溶液在0°C下混合后升温至30°C(记为0时)。接下来以5分钟为间隔按表中所述加入... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 阻遏物的浓度增至5倍亦不能产生更强的抑制(数据未给出)。同样,如果在阻遏物– DNA复合体形成后才加入CRP和RNA聚合酶,即使混合物孵育时间长达30分钟,也只会产生背景水平的乳糖操纵子RNA。加入5倍过量的CRP和RNA聚合酶也不能消除阻遏(数据未给出)。布儒瓦和里格斯已经对乳糖操纵子阻遏物–乳糖操纵子DNA复合体的稳定性进行过描述[7],他们曾经测量过阻遏物与放射性标记的乳糖操纵子DNA的结合情况。 英文
图2.起始前复合体的稳定性。实验按表1描述的步骤进行。○:CRP和聚合酶在阻遏物之前加入;●:CRP和聚合酶在阻遏物之后加入;□:对照,未加入阻遏物。
英文
CRP对DNA具有亲和力,且这种亲和力在环AMP存在的情况下显... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
(b)新的启动子假说认为:乳糖操纵子ps突变在操纵基因附近产生了一个启动子位点(图3c)。尽管阻遏物与操纵基因的结合以及对正常启动子转录的抑制依然会发生,但是RNA聚合酶对新启动子位点的结合不再受到阻遏。如果是阻遏物首先与这种启动子位点结合,那么RNA聚合酶就不能再结合这种新型启动子了,但在正常位点的结合不受影响。这个模型通过引入两个启动子位点解释了观察到的部分抑制和竞争现象。它还假定环AMP–CRP依赖的启动子被转移到靠近乳糖操纵基因的位置;或者说一个突变在乳糖操纵子的一个非常小的区域创造了一个新启动子,这个新启动子同样受到乳糖操纵子阻遏物的阻遏,并且仍为环AMP–CRP依赖。目前还没有发现一例这样的突变。 英文
通过精细结... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | that most nucleotide substitutions in evolution are the result of random fixation of selectively neutral or near neutral mutants. Furthermore, the rate at which neutral mutant genes are substituted in the population per generation is equal to the rate of occurrence of such mutants per gamete5. 中文
There are significant ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | pattern of substitution. We have therefore excluded these slowly evolving parts from our calculation. Fig. 1 illustrates the regression based on all the pairs of comparisons between seven organisms (human, rhesus monkey, rabbit, dog, horse, pig and kangaroo) with observed values shown by dots. The abscissa gives the nu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | If a large fraction of mutations are deleterious as discussed above, every higher organism must suffer a heavy genetic load. According to the Haldane–Muller principle5 the mutation load of equilibrium populations is equal to one to two times the total deleterious mutation rate depending on the degree of dominance of mu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | mutation rate is 1.0 (taking into account the “viability polygenes” of Mukai)15, then the fraction becomes 0.6%. Although we conclude, with Muller16, that the total number of “genes” in man is about 3×104, whereas he assumes a large gene size (corresponding to 30,000 amino-acids), we assume that the genes are much smal... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | In this case, the rate of nucleotide substitution must be very rapid within those parts, for all the mutations are neutral. We estimate this rate approximately as 1/3 × 8.3 × 10–9/yr/nucleotide site, which is one-third of the estimated rate per amino-acid sites in rapidly evolving portions of the fibrinopeptides. We fu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | King, J. L., and Jukes, T. H., Science, 164, 788 (1969).
McLaughlin, P. J., and Dayhoff, M. O., in Atlas of Protein Sequence and Structure 1969 (edit. by Dayhoff, M. O.), 39 (National Biomedical Research Foundation, Silver Spring, Maryland, 1969).
Crow, J. F., and Kimura, M., An Introduction to Population Genetics Theo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 此外,每一代群体的中性突变基因发生替换的速率都与每个生殖细胞发生这种突变的速率相同[5]。 英文
各种蛋白质之间的进化速率存在显著差异。最高速率(血纤维蛋白肽)是最低速率(组蛋白)的1,500倍左右[4]。这意味着该速率取决于蛋白质分子的功能性需求(参考文献1、3以及木村资生和太田朋子尚未发表的研究结果)。有害突变发生的机会越多,进化速率就越慢。每个分子都具有同样的变化速率说明:在每个顺反子的所有突变中,中性突变的比例每年都保持恒定。 英文
有人用9种蛋白质估算出氨基酸替换的平均速率——每个氨基酸位点每年约为1.6×10–9[3]。如果蛋白质进化速率的差异是由于功能性需求上的差异而非它们的突变率差异,那么我们就可以认为任何顺反子发生... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 尽管我们和马勒[16]都确信人类“基因”的总数目大概是3×104,不过他认为基因很大(含30,000个氨基酸),而我们认为基因的大小要小很多(平均只含几百个氨基酸),但大部分DNA是非“编码”的。 英文
哺乳动物的DNA大约是细菌DNA的1,000倍,所以在从单细胞生物进化到哺乳动物的过程中,遗传物质平均要复制10次左右(210=1,024)[17]。在每次对物种中的复制进行固定之后,不论复制的部分是一整条染色体还是一个微小的片段,复制的基因都必然是通过核苷酸替换从最初的基因分化而来的。在这一过程中,许多复制之前是有害的突变在发生复制之后可能反而变成无害了(选择中性),这是因为其中有一套基因为生物体提供了必要的功能。原来有害的突变体... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | THE DNA polymerase found in virions of the RNA tumour viruses1,2 can be assayed in two ways. If disrupted virions are incubated without addition of a template, the endogenous viral RNA is copied by the DNA polymerase3-5. If exogenous templates are provided, often these are copied at a much higher rate than the endogeno... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The initial observation was with Moloney mouse leukaemia virus (MLV). After 20 min of incubation, the product of the virion DNA polymerase reaction was extracted with “Sarkosyl”, purified on a “Sephadex G-50” column, boiled to denature the secondary structure and centrifuged to equilibrium in a Cs2SO4 gradient. The pri... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 3.0 ml. The samples were placed in polyallomer tubes, a cushion of 0.15 ml. of saturated Cs2SO4 was carefully placed at the bottom and the top was covered with “Nujol”. The solutions were centrifuged for 65–70 h at 33,000 r.p.m. and 23°C in a Spinco SW 50.1 rotor in a model L ultracentrifuge. All the gradients containe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | dodecyl sarcosinate. The samples were further incubated for 5 min at 37°C. Portions were withdrawn from the samples to measure acid-insoluble material. The 2, 5, 10, 15 and 30 min products in a typical experiment had 51,000, 165,000, 280,000, 400,000 and 500,000 total c.p.m. respectively. The products were then separat... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Treatment of the DNA polymerase products with alkali in conditions which hydrolyse all RNA caused them to band in Cs2SO4 at a lower average density than the boiled product (Fig. 2c). The bands were quite broad, indicating a low molecular weight. The samples from later times of incubation gave a sharper band which centr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | of the endogenous reaction, supporting the idea that these two systems are comparable. 中文
Fig. 3. Analysis in Cs2SO4 gradients of the product of purified avian myeloblastosis virus DNA polymerase copying 60–70S viral RNA. The polymerase was purified by disruption of the virions with 0.2% “Nonidet–P40”, chromatography ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | product with time of incubation (Fig. 2b) coupled with the increasing size of the DNA product indicated by its decreasing band width (Fig. 2c) suggest that a constant size piece of RNA is attached to a growing DNA strand. 中文
The RNA in the product presumably acts as a primer for the endogenous reaction. Experiments uti... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | This work was supported by a grant from the American Cancer Society and a contract from the Special Virus Cancer Program of the National Cancer Institute. I. M. V. was a fellow of the Jane Coffin Childs Memorial Fund for Medical Research, K. F. M. was a fellow of, and D. B. was a faculty research awardee of, the Americ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Garapin, A.-C., McDonnell, J. P., Levinson, W. E., Quintrell, N., Fanshier, L., and Bishop, J. M., J. Virol., 6, 589 (1970).
Chamberlain, M., and Berg, P., J. Mol. Biol., 8, 297 (1964).
Erikson, E., and Erikson, R. L., J. Virol. (in the press).
Jacob, F., and Brenner, S., CR Acad. Sci., 256, 298 (1963).
Jacob, F., Bren... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
通过热处理对从病毒RNA中释放的产物作进一步分析,现已揭示该物质不是自由DNA。经过30 min或者更短时间的反应,产物中含有表现得很像DNA–RNA双链体的分子,即使经过热变性处理,这种情况仍然存在。对这个结果的一种解释是:此反应的初产物也许是一个通过共价键连接的DNA–RNA分子,用于启动该合成的引物可能是一种RNA。 英文
最初的观测基于莫洛尼氏小鼠白血病病毒(MLV)。培养20 min后,用“肌氨酰”提取病毒体DNA聚合酶反应的产物,再用“葡聚糖凝胶G-50”柱提纯,煮沸使二级结构变性,然后用Cs2SO4密度梯度离心达到平衡。煮沸后产物的主要成分在密度略高于变性后P22噬菌体DNA的地方形成条带(图1a)。存在某种密度... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 反应2 min、5 min、10 min、15 min和30 min后的产物在典型实验中的总c.p.m.值分别为51,000、165,000、280,000、400,000及500,000。使用“葡聚糖凝胶G-50”柱层析,用0.1 M NH4HCO3缓冲液(pH 8.0)洗脱,从而将产物从低分子量物质中分离出来。纯化产物的回收率超过70%。热变性处理:取0.01 ml~0.05 ml产物用0.01 M pH为7.6的Tris-HCl和0.01 M NaCl稀释至0.5 ml,置于沸水浴中5 min,然后迅速冷却。碱水解:将部分产物置于含0.3 M NaOH的同种缓冲液中,沸水浴5 min,快速冷却后用HCl中和至pH为7.0。按图... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 随着培养时间的增加,煮沸产物的密度不断减小(图2b),加之不断变窄的带宽反映出DNA产物的体积在不断增加(图2c),这些都说明有一条大小不变的RNA附着在一条持续增长的DNA链上。 英文
产物中的RNA很可能在内源反应中作为引物。用双脱氧胸苷三磷酸抑制聚合酶反应的实验(斯莫勒、莫里纽克斯和巴尔的摩,已提请出版)表明,DNA附着在引物RNA的3′–OH端。用以测定DNA和RNA中相连接的是否是某些特定核苷酸的实验正在进行中。 英文
目前正在研究附着的RNA的性质。看起来有两个模型可能性最大。一个模型认为60–70S自身会弯曲,形成“发卡”,并且DNA合成始于60–70S RNA的一端。煮沸产物对脉孢菌核酸酶的敏感性不支持这一模型,因为... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | SEVERAL studies have indicated that nicotine is an incentive in smoking. Johnston1 found that heavy smokers reported a pleasurable sensation when given nicotine, whereas nonsmokers reported an unpleasant effect. Lucchesi et al.2 showed that intravenous administration of nicotine diminished the number of cigarettes smok... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | A smoking apparatus was attached to a “Plexiglas” panel covering a 36 cm square opening in the door of each monkey’s home cage. Two tubes, one delivering cigarette smoke and a “dummy” tube with access only to air, were also mounted on the panel. A water solenoid was mounted between the smoke and air tubes. A puff on ei... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Various quantities (50 mg to 200 mg) of nicotine tartrate were dissolved in the water which each monkey obtained through puffing. The amount of nicotine on a given day was always dissolved in 700 ml. of water although the monkeys would usually consume only 300–400 ml. during a puffing session. Increasing dosages of nic... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | mecamylamine alone and the combination significantly decreased overall puffing. Most surprising, however, was the finding that the inhibition of smoking produced by the combination was significantly greater (P<0.05) than that produced by either drug treatment alone. 中文
Table 2. Changes in Smoke Preference of Phoebe in... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Glick, S. D., Canfield, J. L., and Jarvik, M. E., Psychol. Rep., 26, 707 (1970).
Goodman, L. S., and Gilman, A., The Pharmacological Basis of Therapeutics, 585 (Macmillan, London, 1965).
* Present address: Department of Pharmacology, Mount Sinai School of Medicine, New York, NY, 10029.
口服尼古丁的摄入量与猴子的吸烟行为
格利克等
编者按
到20世... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 从表中的数据可以看出:对每只猴子来说,都存在一个口服尼古丁的剂量,这个剂量能明显降低甚至在某些情况下会逆转猴子对香烟–空气的偏好,而不显著影响猴子的总吸入量。 英文
表1.口服尼古丁引起的吸烟偏好的变化
*显著低于对照组,P<0.05。 英文
我们还对其中一只猴子进行了额外的药物实验。因为之前的实验结果已经表明四甲双环庚胺会抑制猴子吸烟,所以我们很想知道四甲双环庚胺会不会拮抗口服尼古丁对吸烟的抑制,也就是说,这两种处理相结合对吸烟行为的抑制作用是否会比单独给予任意一种时更小。出于这个目的,那只在以前的实验中接受过四甲双环庚胺并在最近的实验中口服过尼古丁的猴子被再次使用。按照前述方法,让这只猴子口服125 mg的尼古丁酒石酸盐。另外... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | IMMUNOGLOBULIN (Ig) determinants, presumably functioning as antigen receptors, can be demonstrated on the surface of lymphocytes in various ways1. The distribution of Ig determinants on the cell surface, when living lymphocytes have been studied in suspension with fluoresceinated anti-Ig antibodies, has been variably r... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | CBA spleen cell suspensions were prepared by teasing in veronal buffered saline with 0.1% bovine serum albumin (VBS), Leibovitz medium5 with 10% foetal calf serum (L-15) or phosphate-buffered balanced salt solution (BSS)6. Anti-Ig sera were prepared, fractionated, conjugated with fluorescein and sometimes purified, as ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Direct and indirect immunofluorescence testing gave similar results except where indicated, and results using various anti-MIg sera and various media were not significantly different. Although we only illustrate representative experiments in the tables and figures, each type of experiment was done at least twice and ga... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | When spleen cells were treated with ferritin-labelled anti-MIg and examined by electron microscopy the same phenomenon was observed (unpublished work of S. de P. and M. C. R.). At 0°C the ferritin labelling was patchy and diffusely distributed over the cell surface. At 20°C the labelling was confluent and located over ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Univalent Fab fragments (prepared by digesting G anti-MIg with papain10 and labelling with fluorescein (Table 1)) stained the same percentage of spleen cells as undigested G anti-MIg-Fl but did not induce cap formation (Table 2). Also, ring fluorescence with the Fab antibody was invariably smooth and complete and never... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 4. Effect of anti-MIg concentration on the rate of cap formation. Cells were incubated at 20°C with various concentrations of G anti-MIg-Fl (purified antibody) for 5, 20, 40 and 80 min. Cells were washed at 4°C and examined immediately. The percentage of stained cells showing cap formation is plotted against antib... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | inhibit cap formation. 中文
Table 3. Effect of Cytochalasin B and Colcemid on Cap Formation
* After preincubation at 2×106 cells/ml. in cytochalasin B in L-15 for 30 min at 37°C, cells were incubated with R anti-MIg for 15 min at 37°C washed in cytochalasin B and incubated with G anti-RIg-Fl at 0°C in 3×10–2 M azide for... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | ferritin-labelled anti-MIg at 20°C and examined by electron microscopy not only showed cap localization of the ferritin labelling but invariably contained ferritin-lined pinocytotic vesicles near the Golgi area, underlying the cap. Such vesicles were not seen when the cells were treated at 0°C. 中文
To study further the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | normally. 中文
Table 4. Disappearance of Ig Determinants*
* 2×106 cells were incubated at 37°C in 0.25 ml. of R anti-MIg in L-15; cells were sampled at 20 and 150 min and stained with G anti-RIg-Fl for 30 min at 0°C in 3×10–2 M azide.
† Caps were considered “large” if estimated to occupy at least one-quarter of the cell... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Anti-Ig sera are being widely used to inhibit the function and antigen-binding ability of lymphocytes1. The assumption has been that the anti-Ig inhibits lymphocyte antigen-binding by blocking or by steric hindrance1. Our findings, and those of Takahashi, suggest that modulation of the Ig receptors may sometimes be ope... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | serum gave similar results. Takahashi has recently found that anti-H-2 alone did not cause H-2 modulation, but anti-H-2 plus anti-Ig did modulate if the anti-H-2 was used in low concentrations17. 中文
Fig. 5. Cap formation with anti-θ C3H in indirect immuno-fluorescence with CBA thymocytes. Cells were incubated in dilut... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | D. Webster and A. C. Allison). Prozone effects observed when lymphocytes are stimulated with increasing concentrations of PHA or ALS29 or anti-Ig30 could possibly reflect prozones in inducing cap formation. 中文
If cap formation or pinocytosis play an important physiological role in lymphocyte stimulation or tolerance in... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Martin C. Raff and Stefanello de Petris: National Institute for Medical Research, Mill Hill, London.
Received August 18; revised September 20, 1971.
References:
Greaves, M. F., Transplant. Rev., 5, 45 (1970).
Pernis, B., Forni, L., and Amante, L., J. Exp. Med., 132, 1001 (1970).
Raff, M. C., Sternberg, M., and Taylor... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | McFarland, W., and Schechter, G. P., Blood, 34, 832 (1969).
Allison, A. C., Davies, P., and dePetris, S., Nature New Biology, 232, 153 (1971).
Foerster, J., Lamelin, J.-P., Green, I., and Benacerraf, B., J. Exp. Med., 129, 295 (1969).
Sell, S., and Gell, P. G. H., J. Exp. Med., 122, 423 (1965).
Mitchison, N. A., Immuno... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | † 将兔抗鼠免疫球蛋白γ球蛋白在37°C、0.01M巯基乙醇存在的条件下用木瓜蛋白酶(1份木瓜蛋白酶对应100份γ球蛋白(重量比))消化18h,得到的抗原结合片段在“葡聚糖G-100”上分离。
‡ 山羊抗鼠免疫球蛋白或山羊抗鼠免疫球蛋白荧光标记物经“琼脂糖”免疫吸附柱洗脱提纯[33]。
§ 提纯后的山羊抗鼠免疫球蛋白按如上条件在0.005M二硫苏糖醇存在的条件下消化4h。抗原结合片段的分离方法如上所述并照以前描述过的方法结合[3]。 英文
除另有说明的以外,直接和间接的免疫荧光检验都给出了相似的结果;当使用多种抗鼠免疫球蛋白血清和多种培养基时,结果也没有表现出显著差异。虽然我们在图表中只举例说明了具有代表性的实验,但每种实验都至少重... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 用山羊抗鼠免疫球蛋白抗原结合片段荧光标记物进行染色时未发现斑点荧光,这说明表面免疫球蛋白决定簇的斑状分布可能也是由抗免疫球蛋白抗体的多价结合引起的,在用多价标记抗体进行观察时,需要注意对诸如H-2等其他表面抗原引起的斑状分布的解释[11]。 英文
表2.用抗免疫球蛋白抗原结合片段不能导致冠状分布的形成
* 将细胞在20°C下孵育40min。用山羊抗鼠免疫球蛋白抗原结合片段荧光标记物在宽浓度范围内(0.001 mg/ml~1 mg/ml)检验时所得的结果类似。
† 将细胞在37°C下用兔抗鼠免疫球蛋白孵育20min,冲洗并在0°C下用山羊抗兔免疫球蛋白荧光标记物孵育30min或在37°C下孵育20min。未经消化的抗鼠免疫球蛋白和其... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 当用电子显微镜观察20°C下用铁蛋白标记的抗鼠免疫球蛋白染色的脾细胞时,不仅能在冠状形成中找到铁蛋白标记物,还总能在冠状染色下方的高尔基区附近发现包含有铁蛋白的胞饮泡。在0°C下处理细胞时观察不到这样的小泡。 英文
为了进一步研究细胞表面免疫球蛋白的消失现象,将脾细胞在37°C下用未标记的兔抗鼠免疫球蛋白孵育。分别在10min和3h后冲洗细胞,并于0°C下用含叠氮化物的山羊抗兔免疫球蛋白荧光标记物处理这些细胞(表4)。10min时,40%~50%的细胞被染上色;大多数显示出冠状荧光。3h时,只有20%~30%的细胞被染色,许多被染色的细胞在细胞的一极只有少量荧光斑(表4)。如果在0°C的叠氮化物中用抗鼠免疫球蛋白荧光标记物替换山羊抗... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 为了排除冠状形成是免疫球蛋白决定簇和(或)B细胞所特有的可能性,我们先用具有不同稀释度的抗θ血清,然后用某一恒定浓度的抗鼠免疫球蛋白荧光标记物来处理胸腺细胞,以期诱导出该细胞的冠状形成。当使用高浓度的抗θ时(如同之前报道的实验),只有环状染色出现(图5);但当使用较低浓度的抗θ时,冠状形成发生。在37°C时用稀释的抗θ和0°C时用抗鼠免疫球蛋白荧光标记物处理胸腺细胞的实验中,冠状形成没有发生(图5),这表明在仅有抗θ的条件下孵育30min并不能引起冠状形成。如果用稀释的抗θ处理胸腺细胞,再用未标记的兔抗鼠免疫球蛋白在37°C下孵育20min或2h,接着在0°C下用山羊抗兔免疫球蛋白荧光标记物处理,则孵育2h的冠状染色要小于孵育了20... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
(邓铭瑞 翻译;秦志海 审稿)
Immunoglobulin E (Reagin) and Allergy
D. R. Stanworth
Editor’s Note
In 1921, Carl Prausnitz showed it was possible to induce allergic sensitivity in non-allergic people by injecting them with sera from an allergic person. That landmark paper demonstrated that immediate hypersensitivity was mediated ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | There soon followed similar demonstrations of the local transfer of human hypersensitivity to many common inhalants (such as grass pollens, animal danders and house dusts); the Prausnitz–Küstner (P–K) test, as it is known, being used as an alternative to direct skin testing in the diagnosis of hay fever and allergic as... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | heterologous guinea-pigs for relatively short times. Human antibodies (γG type) against diphtheria toxoid likewise disappear rapidly when injected into isologous human skin (with a half-life of 12 h)3, whereas reagins transferred isologously have been estimated4 to have a “half-life” of 15 days. 中文
Quantitative P–K tes... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The biological properties of reagins revealed by these early investigations, based principally on P–K testing, are summarized in Table 1. This was the position around 1940, when techniques of free-solution electrophoresis and ultracentrifugation were first applied to the fractionation of plasma proteins. Although such ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | As in the characterization of many other minor active protein constituents of biological fluids, it was the advent of zone-fractionation procedures which gave the first definitive indication of the physico-chemical characteristics of the skin sensitizing factor. Thus, zone electrophoresis of allergic sera in starch blo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 1. A comparison of the physico-chemical properties of the five major human immunoglobulin classes. a, Zone electrophoresis; b, gel-filtration; c, ion-exchange chromatography on DEAE-“Sephadex” (reproduced from ref. 26, by courtesy of the authors).
中文
The problem then was to show that skin sensitizing activity wa... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Were reagins a unique type of immunoglobulin (a prospect on which I had speculated in 1963 (ref. 18))? The discovery of a new human immunoglobulin class (IgD or γD)19, which resembled γA globulin electrophoretically, seemed a possibility; but several independent investigations suggested this immunoglobulin did not poss... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | classes of immunoglobulin and which were used in radio-immunoelectrophoresis to provide evidence that a radio-labelled ragweed allergen (E) preparation combined with the reagin isolated from ragweed-sensitive individuals’ sera. 中文
Ishizaka and associates23 suggested that reagin activity was carried by a unique immunogl... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | This similarity in sedimentation coefficient between the new type of myeloma protein and reagin could have been fortuitous, but it seemed significant that the myeloma protein isolated from the serum of patient “ND” was the first known type of immunoglobulin to have similar size characteristics to the skin sensitizing f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | over-production of monoclonal forms of the major immunoglobulin classes has often been seen in plasmocytic and lymphocytic neoplastic disorders. 中文
Immunological and chemical studies25 indicated that the myeloma protein IgND was a new class of immunoglobulin, with similar light chains to those in the other four classes... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | illustrated schematically in Fig. 2) only those incorporating the Fc region had the inhibitory activity of the parent molecule. Similar findings have resulted from inhibition studies in sub-human primates (for example, rhesus monkeys and baboons) which, like non-allergic humans, have proved receptive to sensitization b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | in autoimmune haemolytic anaemia). 中文
Fig. 3. a, Diagrammatic comparison of the properties of antibody and myeloma γE molecules, showing mode of attachment to target cells (this is by means of sites in the Fc regions). b, Mode of interaction of γG type cytolytic antibody molecules with target cells, showing subsequent... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The emergence of in vitro alternatives to the P–K test in humans, and the PCA test in sub-human primates, is facilitating the delineation of the biochemical events set in train by the combination of cell-bound γE antibody and allergen. Such systems are based on passive sensitization by γE antibodies of chopped human lu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | those more drastic processes induced by cytolytic antibodies (for example of the γG type) with the aid of the complement system. As I have already implied (Fig. 3), the type of process evoked depends on the manner in which the antibody is presented to the cell. Antibodies of the γE type seem particularly suited to bind... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | quaternary structural characteristics. It seems likely (as discussed fully elsewhere41) that the two structural features which will prove to distinguish sensitizing antibodies will be an ability to bind strongly to complementary tissue sites with no accompanying loss in the conformational integrity of their Fc region (... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | question then to be answered is whether groups exposed from the Fc regions of the cross-linked antibody molecules act cooperatively to form the activation site. In this event, the activation site could be linked to the active site of an enzyme, which of course is usually contained within a single polypeptide chain. Alt... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | It is suggested that, as in the classical reagin-allergen mediated reaction, the exposure of tissue activation sites within the Fc region of the γE molecule triggers the release of the pharmacologically active mediators. But the cross-linking process which induces the required conformational change is less efficient th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | rabbit) γG molecules where biological activities (for example heterologous skin reactivity and complement fixability), and new antigenic determinants (similar to those formed on specific antigen-antibody combination) are induced by non-specific denaturation treatments. Moreover, recent studies49 on the nature of the st... | 400套付费套装书 |
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