Gametangial development in Allomyces macrogynus

The possible role of mitochondria in determining the sex of the gametangia of Allomyces macrogynus was investigated. Quantitative studies of mitochondrial distribution in vegetative hyphae confirmed previous reports of apical mitochondrial clustering. However, by the time the male and female gametangia were partitioned off, no significant difference in mitochondrial distribution between the two sexes was present. Possible mechanisms for the redistribution of mitochondria during early differentiation are discussed. In addition, cytochrome oxidase activity was demonstrated in all mitochondria of both male and female gametangia by the use of diaminobenzidine. It is concluded that neither mitochondrial distribution nor differential mitochondrial activity plays a determining role in the differentiation of the sexual cells in Euallomyces.Abbreviations %M percent area occupied by mitochondria - DAB diaminobenzidine     

Circadian variation of cytosol glucocorticoid receptors in human polymorphonuclear leukocytes (PMN) and mononuclear cells (MN) in a normal population

Glucocorticoid cytosol and whole cell receptors from human PMN's have been quantified, and compared to those of human MN leukocytes on the same blood sample. The normal cytosol PMN receptor density (N = 15) averaged 1,254 +/- 105 (SE) molecules bound/cell at 0900 h and increased significantly to 1,497 +/- 98 at 2,100 h (P less than 0.02). MN cell cytosol receptor density was 1,198 +/- 145 at 0900 h and increased significantly to 1,551 +/- 117 molecules bound/cell at 2,100 h (P less than 0.01). Corresponding whole cell receptor densities at 0900 h were 2,845 +/- 273 (PMN) and 3,547 +/- 290 (MN) and these did not change significantly at 2,100 h. Conclusions: Cytosol receptors in normal human PMN and MN cells increased significantly at 2,100 h from the 0900 h level while serum cortisol levels were dropping. Whole cell receptors in the same PMN and MN cell samples did not change significantly between 0900 and 2,100 h. The normal circadian variation in serum cortisol influences the distribution of the glucocorticoid receptor between the cytosol and the nucleus, but does not influence the amount of receptor available to the whole cell. This is the first time that an endogenous physiological variation of cortisol concentration has been utilized to demonstrate a corresponding change in receptor capacity in vivo.     

Synthesis of Quinazoline C-Nucleosides: A New Class of 6:6 Bicyclic Purine-Like Analogues.1

Abstract

The quinazoline C-nucleoside congeners of adenosine (1) and inosine (2) have been obtained by radical-induced addition of 4-bromobutyronitrile to C-ribosyl acrylonitrile 10. A base-catalyzed Ziegler-Thorpe cyclization of the dinitrile thus obtained (11) followed by aromatization with DDQ afforded key intermediate 6-ribosylated anthranilonitrile 14 and its α-isomer. Annulation of a pyrimidine ring onto 14 or onto the corresponding o-amino-amide followed by deblocking with MeOH/HCl finally gave 1 or 2 respectively.     

Bile acids: the role of peroxisomes

It is well established that peroxisomes play a crucial role in de novo bile acid synthesis. Studies in patients with a peroxisomal disorder have been indispensable for the elucidation of the precise role of peroxisomes. Several peroxisomal disorders are associated with distinct bile acid abnormalities and each disorder has a characteristic pattern of abnormal bile acids that accumulate, which is often used for diagnostic purposes. The patients have also been important for determining the pathophysiological consequences of defects in bile acid biosynthesis. In this review, we will discuss all the peroxisomal steps involved in bile acid synthesis and the bile acid abnormalities in patients with peroxisomal disorders. We will show the results of bile acid measurements in several tissues from patients, including brain, and we will discuss the toxicity and the pathological effects of the abnormal bile acids.     

A repressor region in the human beta-myosin heavy chain gene that has a partial position dependency.

Expression of the human beta-myosin heavy chain (beta MHC) gene was studied by transient assay in culture and in situ by direct injection of plasmids into adult rat hearts. In this report we describe a unique repressor region located -326/-309 (5'-TTGGTGGTCGTGGTCAGT-3') of the human beta MHC gene that is conserved among the rat, rabbit, and human beta MHC genes. This sequence conferred repression onto heterologous promoters when the sequence was located 5' but not 3' to the promoters. This partial positional dependency suggests that the factor may act by limiting the binding of enhancers, located more proximally, to their DNA binding sites.