The intracellular concentration of cyclic adenosine 3',5'-monophosphate is constant throughout the cell cycle of Escherichia coli

Abstract Both the intracellular and the extracellular concentration of cyclic AMP increases logarithmically in synchronously growing cultures of Escherichia coli . Thus, cyclic AMP by itself cannot regulate growth and division of the bacterium during the cell cycle.     

Characterization of β-amylase and its deficiency in various rice cultivars

 β-Amylase deficiency in various cultivars of rice was examined at the molecular level. Using an antibody against β-amylase purified from germinating seeds of rice, we were able to demonstrate the expression and organization of the β-amylase gene in normal and deficient cultivars. Although β-amylase is a starch-hydrolyzing enzyme, as is α-amylase, the β-amylase protein/gene is expressed differently from the α-amylase protein/gene; i.e. (1) β-amylase is synthesized only in aleurone cells, (2) the enzyme production in the embryo-less half-seeds is not under hormonal control. We identified some cultivars of rice that are deficient for β-amylase activity. We present new evidence that synthesis is blocked at the level of mRNA synthesis in the deficient cultivars. The usefulness of β-amylase as a crop trait is also discussed. Received: 8 May 1998 / Accepted: 5 June 1998     

Rare earth thiocyanate complexes with tripiperidinophosphine oxide: synthesis and characterization. Crystal structure of Pr(SCN)3(tpppO)3

The synthesis and characterization of rare-earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) thiocyanate adducts with tripiperidinophosphine oxide (tpppO) with general formula (RE)(SCN)₃(tpppO)₃ are reported. Conductance measurements in acetonitrile indicate the non-electrolytic nature of the complexes. Infrared absorption spectra evidence that the SCN⁻ ion coordinates through the nitrogen atom (isothiocyanate form) and that tpppO coordinates through the phosphoryl oxygen. X-ray powder patterns suggest the existence of three different crystal forms: (1) La; (2) an isomorphous series including Ce, Nd and Pr; and (3) another isomorphous series, including Sm, Gd, Eu, Ho, Er, Tb, Lu and Y. The visible spectra of the Nd adduct and the calculated parameters β = 0.98, b^1/2 = 0.072 and δ = 1.06 indicate that the metal-ligand bonds are essentially electrostactic. The emission spectra of the Eu compound showed ⁵D₀ → ⁷F_J bands (J = 0, 1, 2), suggesting a C_3v symmetry for the coordination polyhedron. The lifetime of the ⁵D₀ state is 1.28 ms. The emission spectra of the Tb complex presented ⁵D₄ → ⁷F_J bands (J = 4, 5, 6) and the Dy complex showed the ⁴F_9/2 → ⁶H_13/2 band. The structure of the Pr complex showed that the coordination polyhedron is a trigonal antiprism, with the isothiocyanate anions in one base and three tpppO ligands in the other. Thermal analyses (TG-DTG) were carried out for the Ce, Nd and Gd adducts. Mass losses start between 250 and 334 °C. The final residues at 1300 °C are the corresponding phosphates.     

An Ecteola-cellulose chromatography assay for 3′-phosphoadenosine 5′-phosphosulfate: Phenol sulfotransferase

A new assay procedure for phenol sulfotransferase which employs [35S]-3'-phosphoadenosine-5'-phosphosulfate as a sulfate donor and a variety of phenols as sulfate acceptors was developed. The appearance of the 35S-sulfated products or the disappearance of the [35S]-3'-phosphoadenosine-5'-phosphosulfate are determined simultaneously by chromatography of the assay incubation mixtures on Ecteola-cellulose columns, eluting with an NH4HCO3 step gradient. Various acidic, neutral, and basic phenols can be employed as substrates for phenol sulfotransferase using this procedure.     

Hormones and liver mitochondria: Influence of growth hormone,thyroxine, testosterone,and insulin on thermotropic effects of respiration and fatty acid composition of membranes

The effects of hypophysectomy and subsequent administration of growth hormone, thyroxine, insulin, and testosterone were examined in rat liver for the relationship between the thermotropic effects on State 3 respiration (ADP induced) and fatty acid composition of the phospholipid fraction of intact mitochondria as well as of inner membrane vesicles. The Arrhenius profile for energy-linked (succinate) State 3 respiration of mitochondria from hypophysectomized rats lacked the discontinuity at 23.5 °C seen with mitochondria from normal rats. After injections of the hormones the discontinuity representing the transition temperature from gel to liquid crystalline state of lipids occurred at different temperatures: 18.5 °C for growth hormone, 26.0 °C for thyroxine, 19.5 °C for growth hormone + thyroxine, 27.6 °C for insulin, and 25.3 °C for testosterone. The energy of activation between 37.5 and 23.5 °C was 1.9 times greater for hypophysectomy than for controls. Growth hormone was the most effective in restoring the energy of activation to normal, above as well as below transition temperature. The effect of thyroxine appears to be due to a larger stimulation of the State 4 respiration than that of growth hormone, insulin, or testosterone, especially at higher temperatures. Phospholipids extracted from intact mitochondria or inner membrane vesicles of hypophysectomized rats contained less arachidonic acid (20:4) and more linoleic acid (18:2) than those of normal rats. In addition, the contents of some of the minor fatty acids were also changed. Calculated unsaturation index showed an 18.8 and 14.9% depletion in unsaturation in whole mitochondria and inner membranes, respectively. Among the different hormones used to treat the hypophysectomized rats, growth hormone was the most effective in restoring the transition temperature and fatty acid composition to normal levels and increasing the gain in body weight. Although the other hormones increased total unsaturation index to some extent, some of the individual fatty acids were affected differently. Good correlation exists between the unsaturation index of mitochondrial fatty acids and transition temperature of State 3 respiration. These results strongly suggest a role for the hormones, particularly growth hormone, in the control of mitochondrial membrane fluidity of hypophysectomized rat liver, through fatty acid composition of phospholipids.     

A mutant of Halobacterium halobium with constitutive production of bacteriorhodopsin

Abstract A purple mutant of Halobacterium halobium was isolated in a previous study. The 'in vitro' absorption spectra of the cells gave a broad shoulder around 570 nm. The amounts of bacteriorhodopsin were high under any growth condition (including aerobic) inhibitory for the wild-type strain. The mutant grew faster under illuminated microaerophilic conditions and showed faster proton extrusion than the wild-type strain. This evidence shows that the mutant has a constitutive bacteriorhodopsin production not influenced by the oxygen concentration in the medium. However, some stimulation by light was found.     

Neuron differentiation and axon growth in the developing wing of Drosophila melanogaster

Sensory neurons in the wing of Drosophila originate locally from epithelial cells and send their axons toward the base of the wing in two major bundles, the L1 and L3 nerves. We have estimated the birth times of a number of identified wing sensory neurons using an X-irradiation technique and have followed the appearance of their somata and axons by means of an immunohistochemical stain. These cells become immunoreactive and begin axon growth in a sequence which mirrors the sequence of their birth times. The earliest ones are born before pupariation and begin axonogenesis within 1 to 2 hr after the onset of metamorphosis; the last are born and differentiate some 12 to 14 hr later. The L1 and L3 nerves are formed in sections, with specific neurons pioneering defined stretches of the pathways during the period between 0 and 4 hr after pupariation (AP), and finally joining together around 12 hr AP. By 16 hr AP the adult complement of neurons is present and the adult peripheral nerve pattern has been established. Pathway establishment appears to be specified by multiple cues. In places where neurons differentiate in close proximity to one another, random filopodial exploration followed by axon growth to a neighboring neuron soma might be the major factor leading to pathway construction. In other locations, filopodial contact between neighboring somata does not appear to occur, and axon pathways joining neural neighbors by the most direct route are not established. We propose that in these cases additional factors, including veins which are already present at the time of axonogenesis, influence the growth of axons through non-neural tissues.     

Plasma catecholamines: effects of footshock level and hormonal modulators of memory storage

Plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured in male Sprague-Dawley rats before and at several times after training injections of agents known to enhance or to impair later retention performance for a one-trial inhibitory (passive) avoidance task. Two days before testing, each animal was surgically prepared with a chronic tail artery catheter that allows for repeated blood sampling in unhandled rats. Exposure to a single, intense training footshock (3.0 mA, 2.0 sec duration) resulted in an immediate but transient increase in plasma levels of EPI and to a lesser extent NE. Plasma levels of both catecholamines did not differ between unshocked controls and animals that received a weak training footshock (0.6 mA, 0.5 sec duration). An injection of EPI at a dose that enhances retention performance (0.1 mg/kg, sc) resulted in increments in plasma EPI levels of 0.8-1.9 ng/ml from 5 to 40 min after injection. An injection of EPI (0.5 mg/kg, sc) at a dose that produces retrograde amnesia resulted in increments in plasma EPI ranging from 3.7 to 4.5 ng/ml during the 40 min after injection. Plasma NE levels were not significantly altered following an EPI injection. A single injection of adrenocorticotropin (ACTH, 0.3 or 3.0 IU per rat) did not alter the plasma catecholamine responses to training with a weak footshock. Similarly, the synthetic ACTH analog, Organon 2766 (125 or 250 mg/Kg) did not affect plasma catecholamines in untrained (unshocked) rats.These results demonstrate that significant increments in plasma levels of NE and EPI occur shortly after inhibitory avoidance training. Furthermore, an injection of EPI that enhances retention of an inhibitory avoidance task mimics the magnitude, though not the temporal characteristics, of the endogenous adrenal medullary response to a training footshock. Other hormonal treatments (ACTH and Organon 2766) which enhance memory storage do not affect plasma levels of NE and EPI.