The most conserved nuclear-encoded polypeptide of cytochrome c oxidase is the putative zinc-binding subunit: primary structure of subunit V from the slime mold Dictyostelium discoideum.

A full-length 515 base pairs cDNA for cytochrome c oxidase subunit V of D. discoideum was isolated from a lambda gt11 expression library. The encoded polypeptide, whose identity was confirmed by partial protein sequencing, is 119 amino acids long (Mr = 13,352) and does not contain a cleavable presequence. The protein, which is homologous to human subunit Vb and yeast subunit IV, exhibits the highest degree of sequence conservation found among nuclear-encoded subunits of cytochrome c oxidase from distantly related organisms. All the invariant residues are clustered in two regions of the C-terminus which include the putative amino acids involved in the coordination of the Zn ion tightly associated to eukaryotic oxidase.     

Assay of β-galactosidase activity by Flow Injection Analysis (FIA)

Summary A novel method to analyze -galactosidase by Flow Injection Analysis is presented with a linear working range extended to at least 2150 U/mL, being the detection limit 25 U/mL with 55 samples per hour frecuency and a BSD of 0.954% versus 2.4% obtained by manual assay. The method was tested with optimal results with samples from Escherichia coli cultures producing -galactosidase.     

Pentacyclic steroids,part XVI,studies on the total syntheses of racemic 1,6-dithiabenz[3,4]estra-3, 5(10),8,14-tetraen-17-one and its D-homo analogue

The total syntheses of racemic 1,6-dithiabenz[3,4]-estra-3,5(10), 8,14-tetraen-17-one [VII]and 1,6-dithiabenz-[3,4]-D-homoestra-3,5(10),8,14-tetraen-17a-one [IX]starting fron isothiochroman-4-one [I]are described.     

Enzymes Related to Monoamine Transmitter Metabolism in Brain Microvessels

The activities of tyrosine hydroxylase, aromatic L-aminoacid decarboxylase, monoamine oxidase, and catechol-O-methyltransferase were measured in microvessel (capillaries and venules), parenchymal arterioles, and pial vessels from rat brains, and the decarboxylase activity was compared in brain microvessels from rabbit, cat, dog, pig, cow, baboon, and man. Cranial sympathectomy was performed to estimate the neuronal contribution to the enzyme activities. All vascular regions had substantial activities of the various enzymes studied. The activity of aromatic L-aminoacid decarboxylase in cerebral microvessels was high in rat, dog, pig, cow, and man; intermediate in rabbit and cat; and low in baboon. In addition to this enzyme, cerebral microvessels also contained tyrosine hydroxylase and monoamine oxidase. Aromatic aminoacid decarboxylase and monoamine oxidase serve an enzymatic barrier function at the microvascular level, whereas the main function of tyrosine hydroxylase is probably to synthesize monoamines within nerve terminals that remain in close association with microvessels under the conditions used for preparation of the microvascular fraction. In larger intracerebral and pial vessels monoamine oxidase was present both in the wall itself and in perivascular sympathetic nerves; the remaining two enzymes had a primarily neuronal localization. The latter types of vessels also contained catechol-O-methyltransferase in their walls.     

Localization of metabolites which are regulators of extracellular protease synthesis in Pseudomonas fluorescens bacteria

The effect of over forty low molecular weight substrates on the growth and synthesis of exocellular neutral proteases was studied in Pseudomonas fluorescens. Neutral exoproteases were found to be regulated enzymes. Glucose did not repress the synthesis of exocellular proteases; the regulation of their synthesis by amino acids involved the mechanism of induction. The data suggest that the primary intracellular inductors of the synthesis of exoproteases are formed for different groups of amino acids at different levels of their utilization by the cells, viz. at the level of transport and at the level of the first steps in the degradation of their carbon backbones. The paper discusses possible molecular mechanisms for integrating the signal of the primary intracellular inductors, which directly regulate the activity of the operon(s) of neutral exocellular proteases.     

Distribution patterns of formaldehyde-induced fluorescence of hypothalamic monoamines

Summary The adventitial cells surrounding the spermatheca of the reproductive system of Sonorella santaritana (Mollusca: Gastropoda) appear to have an unusual system of vesicles. Electron micrographs of the membranes forming these vesicles show that they have multiple openings to the cell's exterior and that each opening has a pore complex. In addition, secondary vesicles appear to be generated by the primary vesicles. Evidence is presented suggesting that these vesicles represent a previously unreported membrane transport system.Southwestern Medical School and Veterous Administration Hospital Dallas, Texas, USA     

Development of ocularity domains and growth behaviour of axon terminals

Ontogenetic development of ocularity domains — stripes, patches and layers in cortex, colliculus superior and lateral geniculate nucleus — is the result of organization that may either be intrinsic to the postsynaptic structure or induced to it by the afferents. A specific type of axonal growth behaviour that was recently proposed as a basis for ontogenetic development of retinotopy is sufficient to account also for ocularity domains. No intrinsic organization in the postsynaptic structure is required. The latter merely serves as a propagating medium for markers carried by the presynaptic terminals. Computer simulations demonstrate the mechanism to be complete and consistent.     

Computer analysis of Feulgen hydrolysis kinetics

Summary A least squares fit of Feulgen hydrolysis time curves to the Bateman function is performed using an especially adapted parameter transformation together with a standard conjugate gradients iteration procedure. The method has been applied to a large number of measured data, and the use and limits of the computer evaluation are discussed.