An Evaluation of the Nile Blue Test for Differentiating Rhizobia from Agrobacteria

The ability of agrobacteria to reduce Nile Blue more strongly than do rhizobia is the basis of a test for separating these two groups (Hamdi 1969). In a modified test using only 35 parts 10° of Nile Blue in the medium, 89 of 90 rhizobia ( Rhizobium japonicum, R. leguminosarum, R. lupini, R. phaseoli, R. trifolii , cowpea, groundnut and Lotus rhizobia) failed to reduce the dye whereas all 24 strains of agrobacteria ( Agrobacterium radiobacter var. radiobacter, A. r. var. tumefaciens and A. r. var. rhizogenes ) reduced it to the colourless state. Only one Rhizobium strain formed 3-ketolactose from lactose, but 13 agrobacteria produced it. Rhizobium meliloti strains (12) gave variable reactions in both tests. The Nile Blue Test detected rapidly, but not slowly growing, strains of agrobacteria present as contaminants of rhizobia cultures even when their initial numbers were small.     

Staining Nerve Fibers with Methylene Blue. An Evaluation of Variables Used in An Immersion Technic

A study of the effects of osmotic pressure, pH, the presence of dextrose, acetate, pyruvate or lactate, and agents affecting cell permeability during supravital staining by methylene blue was made by means of an immersion technic. Mesentery and intestine of dogs and cats were used. Penetration of the dye was limited to the mesentery and more superficial layers of intestine. Conditions which facilitated the characteristic differentiation of of nerve fibers were: continuous oxygenation of the staining solution, pH about 5.6 stabilized by phosphate buffer, and the presence of small amounts of acetate and lactate. Young animals' tissue stained better than old. Methylene blue was a much more effective staining agent than less completely methylated thionins.     

The number of neurophysins in the rat. Influence of the concentration of Bromophenol Blue, used as a tracking dye, on the resolution of proteins by polyacrylamide-gel electrophoresis

1. The concentration of Bromophenol Blue used as tracking dye in polyacrylamide-gel electrophoresis affected the resolution of rat neurophysins. 2. A final dye concentration of 1mug/ml in the tris-glycine running buffer was found to give the best results. 3. The presence of two major and one minor neurophysin(s) in the rat was confirmed. 4. The two major proteins were found to re-run as single discrete bands, which had the same mobilities in the absence of dye and different mobilities in its presence.     

Metachromasia of basic dyes induced by mercuric chloride. I

Summary Interactions of the cationic dye methylene blue with mercuric chloride have been studied conductometrically, analytically and spectrophotometrically. Methylene blue produces red colored precipitate with mercuric chloride; in presence of large excess of mercuric chloride a strong metachromasia is induced in the dye. Metachromasia induced by mercuric chloride is more hypsochromic as well as hypochromic than that induced by chromotopes like heparin. The complexes formed between methylene blue and mercuric chloride have variable compositions, the complex responsible for the red metachromatic color of the dye has the composition 2 dye: 1 HgCl₂. A model has been proposed for the metachromatic complex consisting hexa-coordinated mercury, dye is coordinated to the mercury by donating the lone pair electrons of terminal nitrogen. The non-metachromatic dye capri blue also interacts with mercuric chloride but without any change in the visible spectrum. Potassium iodide also gives metachromatic reddish blue colored precipitate with methylene blue.University Research Scholar.     

An Improved Fixing Solution for Methylene Blue Preparations

A method is described which combines the writer's hot celloidin technic¹ with a form of the clearing-before-cutting procedure. The method requires only 16–17 days and yields a block which may be cut in any microtome, the sections being as thin as those afforded by paraffin with comparable material. The advantages of celloidin over paraffin, listed in the writer's earlier paper, are retained in the present method which, altho consuming more time than the hot process, requires less skill and gives superior results.     

海藻溴酚化合物对糖尿病大鼠抗氧化水平的影响

目的:本研究通过建立糖尿病大鼠动物模型,观察海藻溴酚化合物A、B对糖尿病大鼠机体抗氧化水平的影响。方法:采用STZ注射法制作糖尿病(DM)大鼠模型,随机分为空白对照组、糖尿病模型组、化合物A低剂量组及高剂量组、化合物B低剂量组及高剂量组,灌胃给药12周。12周末处死大鼠,测肾匀浆中谷胱甘肽过氧物酶(GSH-Px)的活力及丙二醛(MDA)的含量;并采用透射电镜观察大鼠肾组织的病理改变。结果:与空白对照组相比,糖尿病模型组肾组织匀浆中GSH-Px活力下降,MDA含量升高,差异有统计学意义(P<0.05)。各干预组中GSH-Px的活力较糖尿病模型组有升高的趋势,MDA含量有下降趋势。电镜下各干预组肾小球及肾小管病变较糖尿病组减轻,且高剂量组优于低剂量组。结论:溴酚化合物A、B能提高糖尿病大鼠机体抗氧化水平,并能一定程度的改善肾脏病理改化,但其具体机制有待进一步探讨。     

An alternative Alcian Blue dye variant for the evaluation of fetal cartilage

BACKGROUND: The most comprehensive evaluation of vertebrate skeletal development involves the use of Alizarin Red S dye to stain ossified bone and various other dyes to stain cartilage. The dye used most widely to stain fetal cartilage in rodents and rabbits is Alcian Blue 8GX. However, the global supply of this specific dye has been exhausted. Several forms of the dye marketed as Alcian Blue 8GX are now available, although they are not synthesized via the original 8GX manufacturing process. METHODS: One new Alcian Blue 8GX form and two Alcian Blue dye variants were evaluated in rats and rabbits using standard staining procedures. The staining quality of these dyes were evaluated relative to the original form of Alcian Blue 8GX based on cartilage uptake of the dye, clarity of the cartilaginous components, staining intensity of the dye, and overall readability of the specimens under stereomicroscopic evaluation. RESULTS: Staining with the newer form of Alcian Blue 8GX resulted in poor staining quality. The Alcian Blue-Pyridine variant performed well, although staining intensity was less than optimal. The Alcian Blue-Tetrakis variant provided staining characteristics that were most similar to the original form of Alcian Blue 8GX. CONCLUSIONS: Alcian Blue-Tetrakis was markedly better in its ability to stain fetal cartilage than the newer form of Alcian Blue 8GX.     

The Spectrophotometric Evaluation of Mixtures of Methylene Blue and Trimethyl Thionin

Spectrophotometric analysis affords the most convenient means for determining the proportion of methylene blue and trimethyl thionin (azure B) present in a mixture of these two dyes. The method proposed depends upon the determination of an “absorption ratio.” A suitable ratio for the purpose is that of the extinction coefficient at 640 mμ to that at 670 mμ. On account of the difference in absorption maxima of the two dyes, this ratio increases as the percentage of methylene blue decreases. The ratio value for eleven different mixtures is given and a graph is plotted from this data by means of which the proportions of the two dyes present in any mixture can be calculated from the absorption ratio determined as specified.     

The Spectrophotometric Evaluation of Mixtures of Methylene Blue and Trimethyl Thionin

Spectrophotometric analysis affords the most convenient means for determining the proportion of methylene blue and trimethyl thionin (azure B) present in a mixture of these two dyes. The method proposed depends upon the determination of an “absorption ratio.” A suitable ratio for the purpose is that of the extinction coefficient at 640 mμ to that at 670 mμ. On account of the difference in absorption maxima of the two dyes, this ratio increases as the percentage of methylene blue decreases. The ratio value for eleven different mixtures is given and a graph is plotted from this data by means of which the proportions of the two dyes present in any mixture can be calculated from the absorption ratio determined as specified.     

Bromophenol accumulation and sediment contamination by the marine annelids Notomastus lobatus and Thelepus crispus

The occurrence of bromophenols in Notomastus lobatus and Thelepus crispus and associated sediment and porewater was determined. 4-Bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol were identified in N. lobatus with the highest concentrations occurring in the anterior and posterior abdomen and substantially less in the thorax (345, 209, and 6.6 μg/ml of worm, respectively). The concentration of dibromobenzyl alcohol was highest in the tail (last 15 setigers) of T. crispus (1.02 mg/ml of worm), but did not differ among body parts as the bromophenols did in N. lobatus. Concentrations in sediments were significantly reduced from those in the worms and decreased from the inner burrow lining out to 5 cm from N. lobatus burrows. Similarly for T. crispus, concentrations of dibromobenzyl alcohol in the surrounding sediments and porewater were low and increased with proximity to the burrow. For both species, concentrations in surface sediment (upper 1 cm) did not differ from those at 6 cm depth. Several lines of evidence indicate that these compounds are produced by the worms and hence their presence in sediments is derived from the worms. The contamination of sediment by these bromophenols has important implications for the structure and activities of benthic-associated communities.     

An Update on Protein Stains: Amido Black, Coomassie Blue G, and Coomassie Blue R

Samples of amido black, Coomassie blue G, and Coomassie blue R obtained over a number of years were tested for dye content, impurities, and effectiveness for staining proteins after polyacrylamide gel electrophoresis and for protein dye-binding assays. Some impurities produced reactions resembling metachromasia with specific proteins, although instances of true metachromatic staining are also reported. Several simple assays are given for determining dye content and relative levels of impurities. Recommendations are made for selecting batches of commercial dyes which are most likely to perform satisfactorily.