The cytosol receptors for progesterone in the different parts of rabbit fallopian tube and uterus during ovum transport

Progesterone receptors were determined in the cytosol from the ampulla, ampullaryisthmic junction and isthmus of rabbit fallopian tube and uterus of estrus and pregnant rabbits. The receptor levels when compared among its various anatomical segments, were the same in ampulla, isthums and uterus but maximum in ampullary-isthmic junction. Significant differences were observed in mated animals at 14, 24, 34, 48, 70 and 144 h after coitus. The receptor concentrations in portions of the fallopian tube showed no significant change between 14 and 24 h after coitus, except for a decrease in ampullary-isthmic junction at 24 h. At 34 h the concentration of receptor further decreased in all parts of the tube. At 48 and 70 h after coitus, receptor concentrations decreased gradually in ampulla and ampullary-isthmic junction, while isthmus showed a gradual increase. At 144 h, the receptor concentration showed no further change in ampulla and ampullary-isthmic junction; however, isthmus showed a decline. The uterine receptor concentration declined steadily from estrus till 70 h after coitus, however, it was increased at 144 h. The dissociation constant (K_d) of cytosol receptor in all the tissues at estrus and during early pregnancy was found similar. The implications of these changes in relation to the normal ovum transport have been correlated in this paper.     

Effects on adenylate cyclase activities of unsaturated fatty acid incorporation into rat liver plasma membrane phospholipids specific modulation by linoleate

The adenylate cyclase activities of the rat liver plasma membrane were measured simultaneously with the incorporation of acyl chains into the membrane phospholipids using oleyl CoA, linoleyl CoA or arachidonyl CoA thioester. The basal, fluoride — and glucagon — stimulated adenylate cyclase activities were increased by the incorporation of linoleate into the plasma membrane phospholipids. Oleyl CoA did not alter the adenylate cyclase activities whereas arachidonyl CoA, at high concentration, decreased the adenylate cyclase activities. These data indicate a specific effect of phospholipid molecular species containing linoleate.     

Complexity of RNA in Eggs of DROSOPHILA MELANOGASTER and MUSCA DOMESTICA

Comparative measurements are presented of the sequence complexity of the RNA stored in the eggs of two dipteran flies, Musca domestica and Drosophila melanogaster. The genome of Musca is about five times the size of the Drosophila genome and contains about 3.6 times as much single-copy sequence. As shown earlier, the interspersion of repetitive and single-copy sequence is of the short-period form in Musca, and is of the long-period form in Drosophila. The egg RNA complexities were determined by hybridization of excess RNA with radioactively labeled single-copy DNA. Complexity is expressed as the length (in nucleotides) of diverse single-copy sequence represented in the RNA. The complexity of the RNA of the Musca egg is about 2.4 x 10⁷ nucleotides, and that of the Drosophila egg is about 1.2 x 10⁷ nucleotides. The RNA of the Musca egg is similar to or very slightly lower in complexity than that of other egg RNAs, e.g., those of Xenopus and sea urchin. Compared to all previously measured egg RNAs, Drosophila egg RNA is low in sequence complexity.     

Rhizogenesis fromNigella sativa protoplasts

Summary Protoplasts were isolated for the first time from cell suspensions ofNigella sativa. These were then cultured in media and observed at regular intervals. Different concentrations of auxin and kinetin were tried with success to obtain root from the callus tissues of the protoplasts.     

Specific localization of 2′,3′-cyclic nucleotide 3′-phosphohydrolase, (Ca/Mg)-ATPase, and acetylcholinesterase in human erythyrocyte membrane

A procedure was developed for the detection of 2′,3′-cyclic nucleotide 3′-phosphohydrolase in myelin. This assay was sufficiently sensitive to detect the low levels of 2′,3′-cyclic nucleotide 3′-phosphohydrolase in human erythrocytes. The 2′,3′-cyclic nucleotide 3′-phosphohydrolase of human erythrocytes was determined to be exclusively associated with the inner (cytosolic) side of the membrane. Leaky ghostsand resealed ghosts were assayed for 2′,3′-cyclic nucleotide 3′-phosphohydrolase, (Ca²⁺/Mg²⁺-ATPase, and acetylcholinesterase activity, and the 2′,3′-cyclic nucleotide 3′-phosphohydrolase profile is the same as that of the (Ca²⁺/Mg²⁺)-ATPase, an established inner membrane maker.     

Isolation of cyanobacterial auxotrophs by direct selection of regulatory-mutant phenotypes

We have isolated a chorismate mutase bradytroph (leaky auxotroph) ofAnabaena sp. PCC 7119 (ATCC 29151) as a spontaneous 6-fluorotryptophan-resistant mutant. The decreased chorismate mutase activity resulted in the production of quantities of the phenylalanine and tyrosine that limited rate of growth. 3-Deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase activity in the mutant was elevated more than twofold over the wild-type activity, suggesting derepression of this enzyme. The physiological deregulation of DAHP synthase and the genetic-based deficiency of chorismate mutase promoted an elevated level of intracellular chorismate, which then overwhelmed the competitive inhibition of anthranilate synthase by tryptophan, resulting in the overproduction of tryptophan and indoleglycerolphosphate. The presence of exogenous serine increased the production of tryptophan at the expense of indoleglycerolphosphate. This indicated that the endogenous potential for increasing the amount of serine available for increased tryptophan production is limited.     

Studies on the mode of oestrogenic inhibition of hepatic synthesis of alpha2u-globulin and its corresponding messenger ribonucleic acid in rat liver.

1. The possible mechanism of the oestrogenic inhibition of the androgen-dependent synthesis of alpha2u-globulin in rat liver was explored by a correlative study of the amounts of alpha2u-globulin, its corresponding mRNA and circulating testosterone in oestrogen-treated male rats. 2. Daily treatments of mature male rats with oestradiol-17beta (10 microgram/100g body wt.) decreased and ultimately stopped the hepatic synthesis of alpha2u-globulin as determined by both hepatic and urinary concentrations of the protein. The oestrogen-mediated decrease in the hepatic synthesis of alpha2u-globulin was correlated with a decrease in the mRNA for this protein. 3. Withdrawal of oestrogen resulted in the recovery of alpha2u-globulin synthesis and an increase in mRNA for alpha2u-globulin. 4. At higher doses of oestradiol-17beta (50 microgram/100g body wt.), synthesis of alpha2u-globulin was totally suppressed. In addition, this treatment resulted in an extended period of androgen-insensitivity during which treatment with androgens induced synthesis of neither alpha2u-globulin nor its corresponding mtrna. 5. it is concluded that the oestrogenic inhibition of alpha2u-globulin synthesis is mediated by an oestrogen-dependent decrease in the hepatic content of translatable mRNA for alpha2u-globulin.     

Effect of intracellular potassium upon the electrogenic pump of frog retinal pigment epithelium

Summary We have studied the hyperpolarizing, electrogenic pump located on the apical membrane of the retinal pigment epithelium (RPE) in anin vitro preparation of bullfrog RPE-choroid. Changes in RPE [K⁺] _i alter the current produced by this pump. Increasing [K⁺] _o in the solution perfusing thebasal membrane increases RPE [K⁺] _i (measured with a K⁺-specific microelectrode), and also depolarizes theapical membrane. This depolarization is due to a decrease in electrogenic pump current flowing across the apical membrane resistance, since it is abolished when the pump is inhibited by apical ouabain, by cooling the tissue, or by 0mm [K⁺] _o outside the apical membrane. Removal of Cl^– from the solution perfusing the basal membrane abolishes the K⁺-evoked apical depolarization by preventing the entry of K⁺ (as KCl) into the cell. We conclude that the increase in [K⁺] _i causes the decrease in pump current. This result is consistent with the finding that [K⁺] _i is a competitive inhibitor of the Na⁺–K⁺ pump in red blood cells.It is possible that the light-evoked changes in [K⁺] _o in the distal retina could alter RPE [K⁺] _i , and thus could affect the pump from both sides of the apical membrane. Any change in pump current is likely to influence retinal function, since this pump helps to determine the composition of the photoreceptor extracellular space.