NOVEL NUCLEOSIDE TRIPHOSPHATE ANALOGS FOR THE ENZYMATIC LABELING OF NUCLEIC ACIDS

We have evaluated several novel nucleotide analogs suitable for enzymatic labeling of nucleic acid targets for a variety of array-based assays. Two new reagents in particular, a C4-labeled 1-(2′,3′-dideoxy-β-D-ribofuranosyl) imid- azole-4-carboxamide 5′-triphosphate 5 and an N1-labeled 5-(β-D- ribofuranosyl)-2,4(1H,3H)-pyrimidinedione 5′-triphosphate 3, were found to be excellent substrates for labeling with terminal deoxynucleotidyl transferase and T7 RNA polymerase, respectively.     

A NOTE CONCERNING NON-UNIFORM POOL LABELING

An analytical relation is suggested, which in certain cases may permit the labeling pattern of a cellular compartment to be computed from the labeling pattern of cells in a precursor compartment.     

THE VALIDITY OF AUTORADIOGRAPHIC LABELING

As part of an experimental evaluation of autoradiographs after administration of ³H-thymidine to rats, we estimated the background distribution of silver grains. the mean level was within normally accepted limits. the distribution of non-isotope induced grains was such that the validity of all labeling studies which do not evaluate background must be subject to question.     

DETECTION OF THE TOXIC DINOFLAGELLATE ALEXANDRIUM FUNDYENSE (DINOPHYCEAE) WITH OLIGONUCLEOTIDE AND ANTIBODY PROBES: VARIABILITY IN LABELING INTENSITY WITH PHYSIOLOGICAL CONDITION

The toxic dinoflagellate Alexandrium fundyense Balech was grown under temperature- and nutrient-limited conditions, and changes in labeling intensity on intact cells were determined for two probe types: an oligonucleotide probe targeting rRNA and a monoclonal antibody (MAb) targeting a cell surface protein. In nutrient-replete batch culture, labeling with the rRNA probe was up to 400% brighter during exponential phase than during stationary phase, whereas MAb labeling did not change significantly with growth stage at the optimal growth temperature. In cultures grown at suboptimal, low temperatures, there was a significant difference between labeling intensity in stationary versus exponential phase for both probe types, with exponential cells labeling brighter with the rRNA probe and slightly weaker with the MAb. The decrease in rRNA probe labeling with increasing culture age was likely due to lower abundance of the target nucleic acid, as extracted RNA varied in a similar manner. With the MAb and the rRNA probes, slower growing cultures at low, nonoptimal temperature labeled 35% and 50% brighter than cells growing faster at warmer temperatures. Some differences in labeling intensity per cell disappeared when the data were normalized to surface area or volume, which indicated that the number of target antigens or rRNA molecules was relatively constant per unit area or volume, respectively. Slow growth accompanying phosphorus and nitrogen limitation resulted in up to a 400% decrease in labeling intensity with the rRNA probe compared to nutrient-replete levels, whereas the MAb labeling intensity increased by a maximum of 60%. With both probes, labeling was more intense under phosphorus limitation than under nitrogen limitation, and for all conditions tested, labeling intensity was from 600% to 3600% brighter with the MAb than with the rRNA probe. Thus, it is clear that significant levels of variability in labeling intensity can be expected with both probe types because of the influence of environmental conditions and growth stage on cellular biochemistry, cell size,rRNA levels, and the number or accessibility of cell surface proteins. Of the two probes tested, the rRNA probe was the most variable, suggesting that in automated, whole-cell assays, it can be used only in a semiquantitative manner. For manual counts, the human eye will likely accommodate the labeling differences. The MAb probe was less variable, and thus should be amenable to both manual and automated counts.     

DETERMINING THE LABELING INDEX IN AUTORADIOGRAPHY

A method is proposed for estimating the labeling index in autoradiographs. It is based on a model for the frequency distribution of grain counts for those cells which have few grains. The method does not require extensive grain counting and provides reasonable estimates even when the background level is high. It is particularly suited for experiments where tumor cells, labeled in vivo, are, autoradiographed after being cultured in vitro.     

巨噬细胞细胞内吞过程中膜受体流动性的测量——两种标记受体方法的比较

本文首次实现了细胞内吞过程中膜受体流动性的测量。实验选择巨噬细胞膜和伴刀豆凝集素A(ConA),分别用Con A-Biotin Avi-din-FITC(ABC法)和Con A-FITC(直接法)两种方法标记巨噬细胞膜Con A受体,比较了这两种方法标记的巨噬细胞Con A受体的荧光强度;利用FRAP(Fluorescence RecoveryAfter Rhotobleaching)技术,分别用两种标记方法测量了巨噬细胞Con A受体的流动性。结果显示Con A-Biotin Avidin-FITC标记的巨噬细胞受体的平均荧光强度比用Con A-FITC标记的平均荧光强度高大约3倍;直接标记法应用于细胞内吞过程中受体流动性的测量在方法学上存在着很大的缺陷,ABC标记法适合于测量细胞内吞过程中膜表面受体的流动性的变化,且灵敏度高、误差小;ABC方法标记受体的测量结果显示,Con A刺激后巨噬细胞膜表面Con A受体的扩散系数和荧光恢复率与静息状态相比呈下降趋势。     

VECTORIAL LABELING OF DINOFLAGELLATE CELL SURFACE PROTEINS1

Our objective was to identify cell surface proteins in the dinoflagellate Lingulodinium polyedrum. Proteins on the surface of living cells that had regions exposed to the external medium were labeled with Na¹²⁵I. After partial purification of membrane proteins and analysis by two‐dimensional gel electrophoresis and autoradiography, a protein of roughly 43 kDa was found to have incorporated the radiolabel. This protein was cloned using a combination of protein microsequencing and PCR amplification. The derived protein sequence in the cDNA has a signal peptide at the N‐terminal end of the protein and thus represents the first plasma membrane protein ever reported for a dinoflagellate. The function of the protein is unknown, but its cloning provides a proof of principle for the general use of vectorial labeling in identifying cell surface proteins of marine algae.     

量子点荧光技术标记肿瘤细胞中HSP的应用研究

目的探讨量子点荧光技术对人肾癌细胞株(ACHN)中不同HSP进行标记的可行性应用。方法利用量子点的荧光特性,免疫细胞化学方法检测体外培养的ACHN细胞中量子点特异性标记的HSP70、HSP90、HSPgp96的表达情况。结果共聚焦荧光显微镜下可见ACHN细胞中HSP70、HSP90、HSPgp96均有明显表达,呈现均匀分布的橙红色强荧光,且量子点在持续激发30分钟后无荧光淬灭发生。结论量子点荧光标记技术能够对不同HSP进行标记,且与传统的标记方法相比具有显著优点,可作为一种新型的检测技术应用于科研及临床标记检测中。     

Effect of CDP-choline on the biosynthesis of nucleic acids and proteins in brain regions during hypoxia

The effect of CDP-choline on the in vivo incorporation of labeled precursors into DNA, RNA, and proteins in cerebral hemispheres, cerebellum, and brainstem of guinea pigs after hypoxic treatment was studied. The labeling of macromolecules extracted from the various subcellular fractions of these brain regions was also determined. Hypoxic treatment affected macromolecular labeling to a different extent in the three brain regions examined. CDP-choline treatment was not able to reverse the effect of hypoxia on DNA labeling, but it was able to remove the effect of hypoxia on RNA and protein labeling. The action of CDP-choline was particularly evident on the labeling of RNA in nuclei and mitochondria of the cerebellum and on the labeling of proteins in microsomes of the three brain regions examined.     

免疫胶体金标记显示波形纤维与核孔复合体的结合

中间纤维与细胞核的关系是一个亟待解决的重要问题。本文采用火鸡红细胞作为研究材料,首先用细胞分级抽提结合免疫印迹反应显示火鸡红细胞中间纤维蛋白为波形纤维蛋白。然后,我们采用细胞分级抽提结合包埋前免疫胶体金标记的方法显示胞质中间纤维被抗波形纤维蛋白抗体-蛋白A-胶体金特异标记。同时,我们显示结合于核孔复合体上的胞质纤维被抗波形纤维蛋白抗体-蛋白A-胶体金所特异标记。本文结果表明,结合于核孔复合体上的胞质纤维是波形纤维,并且提示波形纤维可能通过与Nup 180的结合附着在核孔复合体上,为进一步探讨中间纤维与核孔运输的关系提供了初步实验证据。     

DIURNAL VARIATION IN THE LABELING INDEX OF MOUSE EPIDERMIS: A DOUBLE ISOTOPE AUTORADIOGRAPHIC DEMONSTRATION OF CHANGING FLOW RATES

A diurnal rhythmicity in the labeling index was observed in the epidermis of hairless mice, injected with either ¹⁴C- or ³H-thymidine, at different times during a 24 hr period. A modified autoradiographic technique, using ¹⁴C- and ³H-thymidine and two overlying emulsion layers, makes it possible to clearly differentiate synthesizing cells which are singly labeled with either carbon-14 or tritium, and cells labeled with both isotopes. At various times during a 24 hr period, hairless mice were injected with thymidine-2-¹⁴C and colcemid, followed at 2 or 3 hr by a second injection of ³H-thymidine. The labeling indices were calculated for the ¹⁴C- and ³H-thymidine injection times. These labeling indices were consistent with the control, single isotope, labeling indices and exhibited the same diurnal rhythm. Cells singly labeled with ³H- or ¹⁴C-thymidine have either started or completed DNA synthesis during the interval between the two injections. Flow rates into and out of DNA synthesis, throughout the 24 hr period, can be calculated from these singly labeled cells. The flow rates varied rhythmically throughout the day and paralleled changes in the labeling indices. The influx and efflux flow rates, at all times measured, were not equal. The influx flow rate was reflected in the efflux rate at a time later equal to the duration of S. By means of these flow rates, the per cent of cells in DNA synthesis was calculated for each hour during a 24 hr period. The resulting labeling index curve matches the observed 24 hr diurnal rhythm in labeling indices. By extension of these flow rates through mitosis, the resulting mitotic index curve is comparable to the reported 24 hr diurnal rhythm in mitotic indices.     

THE SYNTHESIS OF DIENE-CONTAINING NUCLEOSIDE PHOSPHORAMIDITES AND THEIR USE IN THE LABELING OF OLIGONUCLEOTIDES

A variety of furan-modified nucleoside phosphoramidite monomers has been prepared and efficiently incorporated into oligonucleotides. These take part in Diels-Alder reactions with fluorescent maleimides to give fluorescent-labeled oligonucleotides. This represents a strategy for oligonucleotide labeling that is orthogonal to amine-based methods.     

THE EFFECT OF LABELING INTENSITY,ESTIMATED BY REAL-TIME CONFOCAL LASER SCANNING MICROSCOPY,ON FLOW CYTOMETRIC APPEARANCE AND IDENTIFICATION OF IMMUNOCHEMICALLY LABELED MARINE DINOFLAGELLATES1

Two different fluorescein isothiocyanate (FITC) conjugates were used to analyze the effect of labeling intensity on the flow cytometric appearance of marine dinoflagellates labeled with antibodies that specifically recognized the outer cell wall. Location of the labeling was revealed by epifluorescence and real-time confocal laser scanning microscopy using an anti-rabbit IgG/FITC-conjugated secondary antiserum. Flow cytometric measurements showed that cells of Prorocentrum species labeled this way could not always be distinguished from unlabeled cells. The labeling intensity increased several times when a biotinylated anti-rabbit IgG secondary antiserum was used in combination with a streptavidin/FITC conjugate. Flow cytometry indicated that the labeling intensity had increased 50%, which resulted in an improved separation of clusters of labeled and unlabeled cells.     

超氧化物歧化酶的自旋标记研究

本文应用对-SH基特异性结合的自旋标记物对Cu_2Zn_2-SOD进行自旋标记研究,进一步观察了电离辐射对-SH基部位的影响,实验结果:(1)自旋标记后的Cu_2Zn_2-SOD表现出典型的弱固定化的ESR波谱信号特征。标记对Cu_2Zn_2-SOD的UV谱无明显影响。这表明该游离-SH基是位于酶蛋白分子的相对表层而不是包埋在疏水内部。(2)标记保温后立即取样及保温后17小时取样测酶活力,发现与未标记酶的活力相同。这表明该-SH基与酶的催化活性无直接关系。(3)在10—100Krad γ-射线照射下,酶活性及ESR信号幅度均随照射剂量增加而下降,两者之间有一定的相关性。     

Differential accumulation of virus-specific RNA during the cell cycle of adenovirus-transformed rat embyro cells.

In adenovirus type 2-transformed rat embryo cells there is a threefold greater incorporation of [3-H]uridine into virus-specific RNA early in S phase than in late S or G2. This heightened accumulation of labeled RNA is true for both nuclear and cytoplasmic virus-specific labeling. Inhibition of DNA synthesis decreases the virus-specific RNA labeling, whereas reversal of inhibition again allows the elevated level of virus-specific RNA labeling.     

AREA RELATIONS BETWEEN LABELING INDEX CURVES FROM MULTICOMPARTMENT CELL KINETICS MODELS.

The study of the multicompartment models in cell kinetics can be simplified by the use of a conservation law relating the integrals, with respect to time, of labeling index in various compartments. We present a proof of the conservation law directed to the nonmathematician, as well as four applications from biology. The first demonstrates a contradiction, which biologists have yet to resolve, between a certain biological model and experimental results. The second and third are simpler proofs of results already proven by other techniques in the literature. The fourth is a result which appears to be new.     

Effects of -amanitin on in vitro labeling of RNA from defined nuclear components in salivary gland cells from Chironomus tentans

The effect of α-amanitin on nucleoside labeling of RNA in nucleoli, chromosomes, nuclear sap, and cytoplasm from Chironomus tentans salivary gland cells was investigated by radioautography and gel electrophoresis. Preribosomal RNA formation and processing in the nucleolus was not measurably influenced by the drug, and both 28 S and 18 S ribosomal RNA were transferred to the cytoplasm. In the chromosomes the heterogeneous RNA labeling was completely inhibited for the large size range (above 45–50 S) and partially for the low range. The labeling of 4–5 S chromosomal RNA was only moderately reduced. Most of the chromosomes showed radioautographically a disappearance of the normal band pattern, but some retained a pattern of weakly labeled bands. The electrophoretic results for the nuclear sap paralleled those for the chromosomes. The effect of α-amanitin on RNA labeling in these cells is similar but not identical to that of the substituted benzimidazole 5,6-dichloro-1(β-D-ribofuranosyl) benzimidazole (DRB).     

Labeling during cleavage (LDC), a new labeling approach for RNA

A new and efficient strategy for labeling of RNA sequences prior to their hybridization on high density DNA chip has been developed. Our approach which combines the fragmentation and the labeling is based on the reactivity of the 3'-phosphate of cleaved RNA fragments with a fluorescent molecule bearing aromatic bromomethyl function.