beta-actinin, a regulatory protein of muscle. Purification, characterization and function.

beta-Actinin, a minor regulatory protein of muscle, was purified from skeletal muscles of rabbit and chicken by DEAE-Sephadex chromatography. beta-Actinin consisted of two subunits, beta I and betaII, with chain weights of 37,000 and 34,000 daltons, respectively. The amino acid compositions were similar, though not identical. It appears that each of the two subunits is associated in solution. beta-Actinin had the following effects on actin: (1) inhibition of reassociation of F-actin fragments; (2) inhibition of network formation of F-actin; (3) inhibition of growth of F-actin fragments; (4) retardation of depolymerization of F-actin and (5) acceleration of polymerization of G-actin. All these actions of beta-actinin can be explained in terms of action as an "ending factor". Experimental evidence favored the view that beta-actinin is bound to one end of the F-actin filament, namely to the end opposite to the direction of polymerization. Fluorescence-labeled anti-beta-actinin stained the middle portion of the A band of myofibrils. Based on the finding that the stain was unchanged on removal of myosin, it is suggested that beta-actinin is located at the free ends of the I filaments of myofibrils. Thus is seems likely that beta-actinin functions as an ending factor for actin filaments.     

Topographic anatomical data on the a.testicularis, a.ductus deferentis and a.cremasterica in ram

130 Ram testes have been used in the study, and the following methods were applied to fill and study the testical arteries: r?ntgenography, stereor?ntgenography, corosive method, Indian ink and gel injections. Variabilities occur as to the site where the a.testicularis arises in rams. Individual differences can also be observed in the arrangement of the epididymal arteries, in most cases, however, they arise from the first loops of the convolution. Both epididymal arteries are considerably thinner than the testicular artery, forming 2 independent vessel convolutions, located at both sides of the convolution of the a.testicularis, and not interfering with the loops of the latter. A.accessoria testis has been found in one ram only. 2 to 3 large waved loops can be observed in the pars marginalis and the a.testicularis of the ram. Bifurcation mostly occurs in the second third of the margo epididymidis. Individual variations have been found at further ramification of the rr.testiculares. The shape of the lobulus testis is indicated by the centripetal branch with its centrifugal twigs. In rams the a.ductus deferentis forms anastomoses both with the branches running from the a.epididymidis caudalis and the a.cremasterica.     

Mouse alpha-macroglobulin. Structure, function and a molecular model.

Mouse alpha-macroglobulin (M-AMG) is believed to be a functional homologue of human alpha 2-macroglobulin (h-alpha 2M). The subunit composition, the tryptic cleavage pattern before and after methylamine incorporation and the two-dimensional tryptic-peptide mapping, however, indicate that these two proteins are structurally distinct. M-AMG is composed of two major types of polypeptides (Mr 163,000 and 35,000) together with a minor polypeptide (Mr 185,000), whereas h-alpha 2M has only one type of polypeptide (Mr 185,000). After incorporation of methylamine, there is no change in the normal tryptic-cleavage pattern of M-AMG; however, tryptic cleavage of h-alpha 2M is severely retarded [Hudson & Koo (1982) Biochim. Biophys. Acta 704, 290-303]. The N-terminal sequence of the 163,000-Mr polypeptide of M-AMG shows sequence homology with the N-terminal sequence of h-alpha 2M. The amino acid compositions of M-AMG and its two major polypeptide chains are compared. Thermal fragmentation studies show that the 163,000-Mr polypeptide is broken down into 125,000-Mr and 29,000-Mr fragments. Trypsin-binding studies show that M-AMG can bind two molecules of trypsin/molecule. Inactivations of the trypsin-binding property of M-AMG and h-alpha 2M with methylamine show similar kinetics of inhibition at 4 degrees C. A structural model of M-AMG is proposed, based on accumulated data.     

Cloning, sequence, and expression of a chitinase gene from a marine bacterium, Altermonas sp. strain O-7.

The gene encoding an extracellular chitinase from marine Alteromonas sp. strain O-7 was cloned in Escherichia coli JM109 by using pUC18. The chitinase produced was not secreted into the growth medium but accumulated in the periplasmic space. A chitinase-positive clone of E. coli produced two chitinases with different molecular weights from a single chitinase gene. These proteins showed almost the same enzymatic properties as the native chitinase of Alteromonas sp. strain O-7. The N-terminal sequences of the two enzymes were identical. The nucleotide sequence of the 3,394-bp SphI-HindIII fragment that included the chitinase gene was determined. A single open reading frame was found to encode a protein consisting of 820 amino acids with a molecular weight of 87,341. A putative ribosome-binding site, promoter, and signal sequence were identified. The deduced amino acid sequence of the cloned chitinase showed sequence homology with chitinases A (33.4%) and B (15.3%) from Serratia marcescens. Regardless of origin, the enzymes of the two bacteria isolated from marine and terrestrial environments had high homology, suggesting that these organisms evolved from a common ancestor.     

This,that, and the other. Managing illness in a first-generation Korean-American family.

The use of Western medicine and of holistic traditional medicine and healing rituals is common in Korean-American families with a chronically ill member. I present a case as an example of the complexity of health management in first-generation Korean-American immigrants. Immigration and acculturation issues, Confucian-related sociocultural and psychological factors, and the psychiatric diagnosis of Western specialists all elicited family conflict leading to emotional and physiologic distress.     

Streptomyces multispiralis nov. sp. and a New Antibiotic,Neohumidin

A streptomycete isolated in our laboratories was found to produce a new antibiotic effective for the control of sheath blight of the rice plant. As a result of taxonomical study it was proved to belong to a new species and therefore it was named Streptomyces multispiralis nov. sp. From its fermented broth, the antibiotic was isolated and crystallized from benzene. After the comparison of its physicochemical and biological properties with those of known antibiotics, it was considered to be a new antibiotic and named neohumidin. It inhibited the growth of certain phytopathogenic fungi, saprophytic fungi, yeasts and gram-positive bacteria.