Use of avidin-biotin-peroxidase complex (ABC) in immunoperoxidase techniques: a comparison between ABC and unlabeled antibody (PAP) procedures

The use of avidin-biotin interaction in immunoenzymatic techniques provides a simple and sensitive method to localize antigens in formalin-fixed tissues. Among the several staining procedures available, the ABC method, which involves an application of biotin-labeled secondary antibody followed by the addition of avidin-biotin-peroxidase complex, gives a superior result when compared to the unlabeled antibody method. The availability of biotin-binding sites in the complex is created by the incubation of a relative excess of avidin with biotin-labeled peroxidase. During formation of the complex, avidin acts as a bridge between biotin-labeled peroxidase molecules; and biotin-labeled peroxidase molecules, which contains several biotin moieties, serve as a link between the avidin molecules. Consequently, a "lattice" complex containing several peroxidase molecules is likely formed. Binding of this complex to the biotin moieties associated with secondary antibody results in a high staining intensity.     

Combination of silver and fluorescent staining for metaphase chromosomes.

A convenient and reliable method for simulatneous visualization of silver staining (Ag-NOR) of the nucleolus organizers and fluorescent bandings in metaphase chromosomes is described. Studies employing this combined procedure on human chromosomes revealed that the Ag-NOR patterns may be characteristic for each chromosome of each individual.     

蚕氨基酸代谢的研究——家蚕与蓖麻蚕的氨基酸和形成甘氨酸、丙氨酸的酶系比较及酮丙二酸的脱羧作用

家蚕(Bombyx mori L.)与蓖麻蚕(Samia,ricini B)的丝蛋白氨基酸含量差异甚为显著;家蚕丝含量最多的为甘氨酸(42.8％),其次为丙氨酸(32.4％);而蓖麻蚕丝则以两氨酸含量为最高(50.5％),其次为甘氨酸(27.8％)(Kirimuru等,1962)。为了阐明丝蛋白主要氨基酸的形成机制,我们曾报道了这两种蚕丝腺中,自L-天门冬氨酸与α-酮戊二酸形成丙氨酸的机制(许延森等,1964a);体液乙醛酸及丙酮酸与丝蛋白相应氨基酸的含量之     

Responses of mammalian metaphase chromosomes to endonuclease digestion

Digestion of fixed metaphase chromosomes by endonucleases (micrococcal nuclease and DNase II) under optimal digestion conditions followed by Giemsa staining produces sharp banding patterns identical to G-bands. In ³H-thymidine labeled, synchronized metaphase cells of the chinese hamster (CHO line), the band induction is accompanied by the removal of DNA. The single strand specific nuclease S1 and DNase I do not produce such banding patterns.     

Identification of a high molecular weight nervous system specific cell surface glycoprotein on murine neuroblastoma cells

An antiserum to N18 neuroblastoma cells has been used to identify a glycoprotein of apparent molecular weight greater than 200 000 D in SDS-polyacrylamide gels. This glycoprotein (Band 1) is found in culture medium of N18 cells. An immunologically similar component can be immunoprecipitated from detergent extracts of enzymatically iodinated or biosynthetically labelled viable cells. Anti-band 1 activity can be adsorbed from the antiserum by intact N18 cells but not four other cultured murine cell lines. Normal adult murine brain also adsorbs anti-band 1 activity but adult murine adrenal, heart, kidney, liver, lung, and spleen do not. Several experiments indicate that band 1 is not myosin heavy chain or the fibroblast LETS protein. Thus band 1 is a newly identified high molecular weight nervous system specific glycoprotein.     

Effects of sodium intake on renal cortical blood flow distribution.

Renal cortical blood flow and superficial cortical blood flow were measured in chronic sodium-loaded, sodium-deprived and normal rats. Neither total renal cortical blood flow was different among the three groups of animals. Alterations in the amount of sodium excreted, therefore, are not related to alterations of renal cortical blood flow distribution.     

Improvement and initial in vivo application of the radioimmunoassay of rat thyrocalcitonin.

Previously we reported a homologous radioimmunoassy for rat thyrocalcitonin (TCT) which was sensitive enough (2--3 ng/ml serum) to measure TCT in thyroid venous blood or thyroid gland extracts but could not detect TCT in peripheral blood even after provocative challenge with iv calcium. In the present study chicken antisera to rat TCT were developed which were sufficiently sensitive (120--240 pg/ml serum) to permit initial evaluation of changes in TCT in rat peripheral blood. The following results were observed: (1) Basal serum TCT in young male Holtzman rats was undetectable, being less than 120--240 pg/ml; (2) induction of marked hypercalcemia by iv calcium increased TCT to approximately 1000--3000 pg/ml within 5 min; (3) thyroid cautery increased TCT to approximately 1000 pg/ml in 5--15 min; (4) calcium gavage (12.2 mg Ca/100 g) produced modest hypercalcemia in 30--60 min and increased serum TCT to approximately 500 pg/ml; (5) injection of isoproterenol raised serum TCT detectably; (6) injection of large doses of gastrin or pentagastrin did not produce detectable increases in TCT 5 or 30 min later. The results show that suitable antisera to rat TCT can be developed in chickens and applied to the measurement, by radioimmunoassay, of elevated circulating levels of TCT in the rat.