Showing papers by "Howard Hughes Medical Institute published in 1970"

The complement system in rheumatoid synovitis. I. An analysis of complement component activities in rheumatoid synovial fluids.

Abstract: Stoichiometric hemolytic assays were used to measure the activities of the first four reacting components of the complement sequence in synovial fluids from patients with seropositive or seronegative rheumatoid arthritis or degenerative joint disease. The pattern of component reductions in the seropositive rheumatoid arthritis fluids was consistent with activation of the complement system by an intra-articular immunologic process.

Specificity of monohydric phenol oxidations by meta cleavage pathways in Pseudomonas aeruginosa T1

Abstract: The oxidation of several mono-hydric phenols by wild type and mutant strains of Pseudomonas aeruginosa T1 has been studied. The data suggest, that a non-specific enzyme sequence of the meta cleavage pathway is induced by all of these phenols, which can catalyze the oxidation of phenol and its analogues to pyruvate, a fatty acid and a carbonyl compound, according to the general scheme of Dagley et al. (1964). Mutants unable to grow on phenol (hydroxylase-negative), have been isolated, and they are also unable to grown on or oxidize the cresols and the xylenols. Revertants of these mutants regain the capacity to grow on all these phenols and are indistinguishable from the wild type. Induced-substrate relationships for the earlier enzymes of the pathway have been determined, e.g., phenol in addition to catechol and the methylcatechols is an inducer for catechol 2,3-oxygenase. Analysis of the enzymic content of cells grown in a variety of steadystate conditions shows (a) that the ratio of the specific activities of the “phenol” hydroxylase and catechol 2,3-oxygenase is constant for each of their analogous substrates; and (b) that induction and catabolite repression of catechol 2,3-oxygenase and the “muconic semialdehyde” hydrolyase are coordinate, but that control of the “phenol” hydroxylase is independent.

The fine structure of Methylococcus capsulatus

Abstract: The fine structure of Methylococcus capsulatus is described. Particular emphasis is focused on the intracytoplasmic membrane system which is organized as a stacked array of flattened saccules. Each saccule is limited by a 75 A unit membrane and lies in close apposition to adjacent saccules. Methylococcus capsulatus is an obligate methylotroph whose sole source of carbon and energy is methane (or methanol). In this study methane oxidation is demonstrated for the first time in a cell-free system. Work is in progress to determine the cellular organelles which constitute the particulate fraction responsible for methane oxidation. The possible role of the intracytoplasmic membranes in energy transfer is considered in relation to the functions of stacked membrane arrays in other animal, plant and bacterial systems.

The origin of small vesicles in neurosecretory axons.

Abstract: The mechanism of release of neurosecretory products from the corpus cardiacum of the stick insect Carausius morosus is discussed. Results of experiments using ferritin as an exogenous marker show a) direct communication between the cavity of the larger (2000 A diameter) vesicles and extracellular space at the axon periphery, and b) ferritin also occurs in smaller vesicles (300 A diameter) derived, by a process similar to pinocytosis, from the axon surface. These findings are discussed in relation to exocytosis and the implications of this mode of release in terms of membrane turnover. It is suggested that neurosecretory products are released into the haemolymph by fusion between the limiting membrane of the neurosecretory droplet and the axon membrane. Small vesicles may be involved in retrieval of membrane material, countering that added in the above way.