Survival Rate and Enzyme Activities ofLactobacillus acidophilusFollowing Frozen Storage

The ability of two strains of Lactobacillus acidophilus, CRL 640 and CRL 800, to survive and retain their biological activities under frozen storage was determined. Freezing and thawing, as well as frozen storage, damaged the cell membrane, rendering the microorganisms sensitive to sodium chloride and bile salts. Both lactic acid production and proteolytic activity were depressed after 21 days at -20 degreesC, whereas beta-galactosidase activity per cell unit was increased. Cell injury was partially overcome after repair in a salt-rich medium. Copyright 1998 Academic Press.     

The evidence for a meiotic process in the euglenineae

Summary Cells of Hyalophacus ocellatus are described which contain either a nuclear figure consisting of a double complement of highly condensed chromosomes arranged in pairs in the anterior half of the cell, or a huge posteriorly-placed nucleus consisting of long granular chromosomes which also show signs of pairing. These nuclear figures are quite unlike interphase nuclei or stages in mitosis and are thought to be stages in euglenoid meiosis.No evidence has been obtained for a sexual fusion of gametes or cells. Previous accounts of sexuality and autogamy in the Euglenineae are historically reviewed and critically discussed relative to the present observations.This paper is dedicated to Professor Dr. E. G. Pringsheim on the occasion of his 80th birthday, with gratitude both for his untiring advice on my research and for his friendship.     

THE DINOFLAGELLATE TRANSVERSE FLAGELLUM: THREE-DIMENSIONAL RECONSTRUCTIONS FROM SERIAL SECTIONS1

Serial sections through in situ transverse flagella of the dinoflagellate Peridinium cinctum f. irregulatum (Lindem.) Lefévre are presented. Three-dimensional reconstructions based upon tangential and radial series show a helically coiled axoneme lying external to and distinct from an accessory strand. Hitherto undescribed vesicles within the expanded flagellar sheath are suggested to provide a decoupling effect between axoneme and strand. The flagellar axis bears two types of hair but anchoring threads between cingulum and flagellum have not been found. Functional and taxonomic implications of these observations are briefly discussed.     

Observations on endonuclear bacteria in euglenoid flagellates

Summary Rod-shaped inclusions in the nuclei and/or cytoplasm of strains ofEuglena spirogyra, Lepocinclis ovum, Strombomonas conspersa andTrachelomonas oblonga var.punctata have been identified as living populations of bacteria by reference to size, shape and ultrastructure. Most strains contain 20–200 bacteria per nucleus. Each bacterial cell is surrounded by a mucilaginous sheath and consists of a double-membraned envelope, dense cytoplasm with small ribosomes, and a filamentous DNA-containing centre. The bacteria multiply to keep pace with euglenoid division but there is no evidence that the euglenoid cells benefit from or are harmed by the association. Attempts to transfer the endonuclear bacteria to uninfected strains and species have been unsuccessful, as have attempts to isolate the bacterium into pure culture. The infected strain ofEuglena spirogyra cannot fix nitrogen. The possible nature of the euglenoid/bacterium association is discussed.Dedicated to Prof. Dr.Lothar Geitler on the occasion of his 70th birthday.     

Paraphysomonas faveolata sp. nov. (Chrysophyceae), a fourth marine species with meshwork body-scales

Paraphysomonas faveolata sp. nov., the eighth described species of this genus of colourless chrysophycean flagellates, has heterokont flagellation, parabasal nucleus and silicified body-scales. It is the fourth known species with meshwork scales, these being of two types: flat “cobweb” scales and scales with a planar “honeycombed” extension arising from a “cobweb” base. The organism is compared with the other species of the genus and the case considered for placing forms with meshwork scales in a new genus, separate from forms with spined scales. This step is not taken and the taxonomic status of the genus is discussed in relation to the Ochromonadaceae and other genera of the Synuraceae.     

Polymorphism of myosin among skeletal muscle fiber types

An immunocytochemical approach was used to localize myosin with respect to individual fibers in rat skeletal muscle. Transverse cryostat sections of rat diaphragm, a fast-twitch muscle, were exposed to fluorescein-labeled immunoglobulin against purified chicken pectoralis myosin. Fluorescence microscopy revealed a differential response among fiber types, identified on the basis of mitochondrial content. All white and intermediate fiber but only about half of the red fiber reacted with his antimyosin. In addition, an alkali-stable ATPase had the same pattern of distribution among fibers, which is consistent with the existence of two categories of red fibers. The positive response of certain red fibers indicates either that their myosin has antigenic determinants in common with "white" myosin, or that the immunogen contained a "red" myosin. Myosin, extracted from a small region of the pectorlis which consists entirely of white fibers, was used to prepare an immunoadsorbent column to isolate antibodies specific for white myosin. This purified anti-white myosin reacted with the same fibers of the rat diaphragm that had reacted with the white, intermediate, and some red fibers are sufficiently homologous to share antigenic determinants. In a slow-twitch muscle, the soleus, only a minority of the fiber reacted with antipectoralis myosin. The majority failed to respond; hence, they are not equivalent to intermediate fibers of the diaphragm; despite their intermediate mitochondrial content. Immunocytochemical analysis of two different musles of the rat has demonstrated that more than one isoenzyme of myosin can exist in a single muscle, and that individual fiber types can be recognized by immunological differences in their myosin. We conclude that, in the rat diaphragm, there are at least two immunochemically distinct types of myosin and four types of muscle fibers: white, intermediate, and two red. We suggest that these fibers correspond to the four types of motor units described by Burke et al. (Burke, R. E., D. N. Levine, P. Tsairis, and F. E. Zajac, III 1973. J. Physiol. (Lond) 234:723-748.)in the cat gastrocnemius.`