A comparative study of serotonin metabolism in helminths and their hosts]

Studies have been made on the content of the main metabolite of serotonin, namely 5-hydroxyindoleacetic acid in parasitic worms from various classes. It was shown that 5-hydroxyindoleacetic acid level is lower than that of serotonin, which is taken as an indication of low catabolism of serotonin in worms. This tendency was observed in helminths from different taxonomic, ecological and age groups invading media with both low and high levels of serotonin metabolism.     

Quantitative determination of the protein content of citrus leaf extracts: A comparative study

Three spectrophotometric methods for the quantitative determination of proteins were compared taking as a reference the method of Kjeldahl. The abnormally high protein values obtained when these methods were applied to soluble extracts were decreased by using protective and precipitating agents. The method of M. M. Bradford (Anal. Biochem. 72, 248–254 (1976)) gave values identical to the method of Kjeldahl when ethylenediaminetetracetic acid, 2-mercaptoethanol, and polyvinylpolypyrrolidone were added to the extraction medium and the soluble proteins were precipitated with trichloroacetic acid prior to protein determination.     

A critical reevaluation of some assay methods for superoxide dismutase activity

We have compared the direct method of pulse radiolysis to the indirect methods of cytochrome c and nitroblue tetrazolium for assaying the superoxide dismutase activity of a compound. We have shown that with pulse radiolysis, where high concentrations of O2- are generated, the "turnover" rate constant, kcat, can be determined directly, while with the indirect methods, where relatively low steady state concentrations of O2- are formed, the value of kcat determined by these methods, can be orders of magnitude lower than that determined directly. The main reason for the lower values obtained with the indirect methods is due to the fast reoxidation of the reduced compound by molecular oxygen. Additional problems which arise with the use of indirect methods for determining superoxide dismutase catalytic activity are discussed.     

A ninhydrin-based assay to quantitate the total protein content of tissue samples

Quantitation of small tissue samples for total protein content is essential for many biochemical analyses. In this study a ninhydrin method for measuring the total protein content of tissue hydrolysates is presented.The ninhydrin reagent is stable at room temperature for up to 1 month in the ethylene glycol-sodium acetate solvent system without the requirement for a nitrogen atmosphere. The reaction was very accurate and precise, with intra- and interassay variations of less than 3% when 5 microg of protein was assayed. All proteins that were investigated contributed the same color intensity per microgram protein as bovine serum albumin. This assay was several times more sensitive than the Coomassie reaction and linear over a greater range of protein concentration.     

A comparative study of machine-learning methods to predict the effects of single nucleotide polymorphisms on protein function

MOTIVATION: The large volume of single nucleotide polymorphism data now available motivates the development of methods for distinguishing neutral changes from those which have real biological effects. Here, two different machine-learning methods, decision trees and support vector machines (SVMs), are applied for the first time to this problem. In common with most other methods, only non-synonymous changes in protein coding regions of the genome are considered. RESULTS: In detailed cross-validation analysis, both learning methods are shown to compete well with existing methods, and to out-perform them in some key tests. SVMs show better generalization performance, but decision trees have the advantage of generating interpretable rules with robust estimates of prediction confidence. It is shown that the inclusion of protein structure information produces more accurate methods, in agreement with other recent studies, and the effect of using predicted rather than actual structure is evaluated. AVAILABILITY: Software is available on request from the authors.     

A comparative study of flavonoids in some members of the Papaveraceae

The leaf flavonoids of the family Papaveraceae were studied.     

A comparative ultrastructural study of the ascospores of some Saccharomyces and Kluyveromyces species

Three types of structure of the ascospore wall were found among the haploid Saccharomyces species examined: a warty wall (S. rouxii), a smooth wall with a single electron-light inner layer (S. bailii) and a smooth wall with a double light inner layer (S. montanus, S. florentinus). The latter type also occurred in Kluyveromyces thermotolerans and K. waltii. In K. fragilis spores the wall had a single light inner layer. The taxonomic implications of these findings were discussed.     

A comparative study of clustering methods for molecular data

The research aim is to use three clustering technologies for establishing molecular data model of large size sets by comparison between low energy samples (LES) and local molecular samples (LMS). Hierarchical cluster of multi-level tree distance relation, competitive learning network of similar inputs falling into the same cluster and topological SOM are used to analyze 6,242 LES and 5,000 LMS. Our experiments show that in SOM, there are 24 to 25 Davies-Boulding clustering index and color map cluster units in the LES more than 10 to 12 in the LMS, which is consistent with the results of hierarchical cluster and competitive learning network in the rough. The hierarchical cluster reflects the biggest inter-cluster distance about 30 for the LES is far larger than that of LMS about 10. The intra-cluster distance of LES about 15 is also far bigger than that of LMS about 3. In SOM, there are more cluster borders of high values (black) reflecting large distance and more clusters in the D-matrix and U-matrix of LES than that of LMS, due to the biggest standard deviation range from -8 to 10 of samples feature of the LES is bigger than that of LMS from -2.5 to 2.5.     

A comparative study of microtubules in some vertebrate and invertebrate cells

Summary An electron microscope study of a variety of invertebrate and vertebrate cell types has supported the postulate that the microtubule is a universal cellular organelle. Microtubules of similar dimensions have been observed in the flagellum and beneath the plasma membrane of Trypanosoma lewisi, in the flagellum, manchette and mitotic spindle of the earthworm (Lumbricus terrestris) spermatid; and in fibroblasts, proximal convoluted and collecting tubule cells of the hypertrophying rat kidney. The specific occurrence and organization of the microtubules in cells undergoing morphological and developmental changes have suggested that these organelles are contractile and that they effectively contribute to the maintenance of cellular form. The possibility that microtubules may function as an intracellular transport system is also suggested.This work was supported by grants CA-04046, GM-08380, and K 3-AM-4932 from the U. S. Public Health Service.