The E1 replication protein of bovine papillomavirus type 1 contains an extended nuclear localization signal that includes a p34cdc2 phosphorylation site.

Bovine papillomavirus (BPV) DNA replication occurs in the nucleus of infected cells. Most enzymatic activities are carried out by host cell proteins, with the viral E1 and E2 proteins required for the assembly of an initiation complex at the replication origin. In latently infected cells, viral DNA replication occurs in synchrony with the host cell chromosomes, maintaining a constant average copy number of BPV genomes per infected cell. By analyzing a series of mutants of the amino-terminal region of the E1 protein, we have identified the signal for transport of this protein to the cell nucleus. The E1 nuclear transport motif is highly conserved in the animal and human papillomaviruses and is encoded in a similar region in the related E1 genes. The signal is extended relative to the simple nuclear localization signals and contains two short amino acid sequences which contribute to nuclear transport, located between amino acids 85 and 108 of the BPV-1 E1 protein. Mutations in either basic region reduce nuclear transport of E1 protein and interfere with viral DNA replication. Mutations in both sequences simultaneously prevent any observable accumulation of the protein and reduce replication in transient assays to barely detectable levels. Surprisingly, these mutations had no effect on the ability of viral genomes to morphologically transform cells, although the plasmid DNA in the transformed cells was maintained at a very low copy number. Between these two basic amino acid blocks in the nuclear transport signal, at threonine 102, is a putative site for phosphorylation by the cell cycle regulated kinase p34cdc2. Utilizing an E1 protein purified from either a baculovirus vector system or Escherichia coli, we have shown that the E1 protein is a substrate for this kinase. An E1 gene mutant at threonine 102 encodes for a protein which is no longer a substrate for the p34cdc2 kinase. Mutation of this threonine to isoleucine had no observable effect on either nuclear localization of E1 or DNA replication of the intact viral genome.     

Phylogeography of the temperate grassland plant Tephroseris kirilowii (Asteraceae) inferred from multiplexed inter-simple sequence repeat genotyping by sequencing (MIG-seq) data

Journal of Plant Research - A group of temperate grassland plant species termed the “Mansen elements” occurs in Japan and is widely distributed in the grasslands of continental East...     

Importance of dormancy and sink strength in sprouting of onions (Allium cepa) during storage

In onion ( Allium cepa L.) postponement of sprouting is necessary to achieve long term storage. We studied the factors determining sprouting during dry storage at 16°C. The period to visible sprouting depends on the length of the dormancy period, if present, and on the growth rate of the sprout. In the three cultivars tested, sprouts were initiated within 2 weeks after harvest indicating the absence of a real dormancy period. Sprout length increased linearly during storage. The mitotic activity of the apex decreased before harvest, was low at the transition from scale to leaf formation, and increased again when the sprout was initiated. From a few weeks before harvest, the initially high fructan content of the scales decreased, leading to a large increase in fructose. The sprout always contained enough carbohydrates for growth (between 50 and 60 mg g⁻¹ dry weight, of which 30% was fructan). The activity of sucrose synthase (EC 2.4.1.13) increased as the sprout grew, indicating an increase in sink strength. Invertase (EC 3.2.1.26) was absent in all bulb organs, during the various developmental stages. Although carbohydrates and enzymes were available for fast sprouting, sprout growth was still linear instead of exponential during dry storage at temperatures favorable for growth (16°C). The relative importance of factors determining sprouting are discussed.     

Light-induced voltage noise in the photoreceptor of Drosophila melanogaster

The Drosophila photoreceptor potential is thought to be composed of discrete unit potentials called bumps. The steady-state receptor potential and the accompanying voltage fluctuations were recorded intracellularly under steady illumination. The occurrence rate, effective amplitude, and duration of the bumps were deduced by assuming a shot noise model. Over a wide range of light intensity, the duration of bumps remained essentially constant (25-30 ms). Below the saturation intensity for the receptor potential, the bump rate was roughly proportional to the intensity, and the adjustment of bumps to smaller size at higher intensity was mainly responsible for the nonlinear behavior of the receptor potential. The reduction in size of bumps at increasing light intensity was found to be due mainly to the diminishing magnitude of the bump current, and not to some other secondary effects. The bump rate saturated at about 3 x 105-106 events/s.     

Tolerance of Low Intracellular pH During Hypercapnia by Rat Cortical Brain Slices: A 31P/1H NMR Study

Metabolic tolerance of low intracellular pH (pH(i)) was studied in well-oxygenated, perfused, neonatal, rat cerebrocortical brain slices (350 microns thick) by inducing severe hypercapnia. In each of 17 separate experiments 80 brain slices (approximately 3.2 g wet weight) were suspended in an NMR tube, perfused with artificial CSF (ACSF), and studied at 4.7 T with 31P and 1H NMR spectroscopy. Spectra obtained every 5 min monitored relative concentrations of lactate or high-energy phosphate metabolites, from which pH(i) and extracellular pH were determined. Unperturbed slice preparations were metabolically stable for > 10 h, with no significant changes occurring in pHi, ATP, phosphocreatine (PCr), inorganic phosphate, or lactate. Different levels of hypercapnia were produced by sequentially perfusing slices with the following different ACSF batches, each having previously been equilibrated with a specific mixture of CO2 in oxygen: (a) 10% CO2, 15 min of perfusion; (b) 30% CO2, 15 min of perfusion; (c) 50% CO2, 15 min of perfusion; (d) 70% CO2, 30 min of perfusion; (e) 50% CO2, 15 min of perfusion; (f) 30% CO2, 15 min of perfusion; and (g) 10% CO2, 15 min of perfusion. At the completion of this protocol slices were again perfused with fresh ACSF that was equilibrated with a 95% O2/5% CO2 gas mixture. In each of five separate 1H and 31P experiments, brain slices were recovered within 2 h after termination of exposure to high CO2. The pHi was determined from measurements of the chemical shift difference between phosphoethanolamine and PCr, using a calibration curve obtained for our preparation.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo conversion of [3H]myoinositol to [3H]chiroinositol in rat tissues.

We report here the in vivo conversion of [3H]myoinositol to [3H]chiroinositol. After labeling intraperitoneally with [3H]myoinositol for 3 days to reach radioisotope equilibrium in urine, [3H]chiroinositol was isolated from tissues and purified after 6 N HCl hydrolysis by two sequential paper chromatographies and high performance liquid chromatography (HPLC). Percent conversion of [3H]myoinositol to [3H]chiroinositol was highest in urine (36%), liver (8.8%), muscle (8.8%), and blood (7.6%) with intestine, brain, kidney, spleen, and heart decreasing in percentage from 2.8 to 0.7%. Labeling of other inositol isomers including scyllo-, neo-, and epi-, and mucoinositol was minimal, approximately 0.06% of [3H]myoinositol. Glucose was unlabeled, but glucuronate, the product of myoinositol oxidation, was labeled up to 1.5% of the [3H] myoinositol. Acid hydrolysates of combined inositol-containing phospholipids contain significant labeled chiroinositol. [3H]Phosphatidylinositols and [3H]glycosylphosphatidylinositols were extracted from liver, muscle, and blood, isolated by thin layer chromatography, and inositols purified by HPLC after acid hydrolysis. Percent conversion of [3H]myoinositol to [3H] chiroinositol was highest in blood (60.4%) followed by muscle (7.7%) and liver (2.2%).     

The effect of cyclooxygenase inhibition on the indices of the thrombocyte-vascular link in hemostasis and on the free-radical processes of lipid oxidation in experimental Salmonella intoxication]

Injection of Salmonella typhimurium endotoxin to the laboratory animals (rabbits) in dose of 1 mg/ml (LD84) induces the particular changes in the thrombocyte vessels system of hemostasis: decrease of aggregatory ability of thrombocytes, increase of thromboxane A2 and prostacyclin activation of lipid peroxidation process. Use of indomethacin--the cyclooxygenase inhibitor--leads to less progressive alterations of the studied parameters of the thrombocyte vessels hemostasis and lipid peroxidation processes.     

Volume elasticity of the ocular avascular compartment in vivo and post mortem

By considering the frequency dependence of the ocular volume elasticity it is possible to locate the static volume elasticity function of the avascular compartment of the eye in vivo. The procedure used involved measuring the dynamic volume elasticity function E=f(P, v), where E=volume elasticity, P=intraocular pressure, and v=frequency, in vivo and post mortem at a frequency higher than the apparent upper mechanical response frequency of the intraocular vascular bed. In addition, post mortem measurements were made of the volume elasticity function at a frequency which was as low as experimentally possible. For practical purposes the latter volume elasticity function may serve as an estimate of the static elasticity function of the avascular compartment in vivo. This is possible in all cases because at the high frequency level the dynamic volume elasticity functions measured in vivo and post mortem are identical.Partly presented by the first author at the 4th Mackenzie Symposium, Stirling 1977Decaased 18.3. 1980