The Schizosaccharomyces pombe cdc6 gene encodes the catalytic subunit of DNA polymerase δ

The cdc6 mutants of Schizosaccharomyces pombe have been classified as being defective in progression through the G2 phase of the cell cycle. We cloned an S. pombe gene that could complement the temperature-sensitive growth of the cdc6-23 mutant. Unexpectedly, the cloned gene was allelic to pol3, which encodes the catalytic subunit of DNA polymerase δ. Integration mapping confirmed that cdc6 and pol3 are identical. The cdc6-23 mutant carries one amino acid substitution in the conserved N3 region of Pol3. Received: 17 October 1996 / Accepted: 19 November 1996     

Effect of a high-protein diet on the gene expression of a trypsin-sensitive, cholecystokinin-releasing peptide (monitor peptide) in the pancreas

The adaptation to a high protein diet of the concentration and mRNA level of a trypsin-sensitive, cholecystokinin-releasing peptide (monitor peptide), which was proposed to be the mediator of the cholecystokinin release in response to protein intake, was investigated in the rat pancreas. Adult rats were placed on one of two isocaloric diets. One group was fed a 22% casein diet (control diet) and the other a 64% casein diet (high-protein diet) for 14 days. In order to quantify the monitor peptide separately from pancreatic secretory trypsin inhibitor (PSTI-II), which is highly similar in its amino acid and mRNA nucleotide sequences to the monitor peptide but has less cholecystokinin-releasing activity, we used specific assay methods: HPLC was used for determining the monitor peptide concentration in zymogen granules and a synthetic oligonucleotide probe for determining the mRNA of the monitor peptide in the pancreas. The concentrations in the zymogen granules and the mRNA levels in the pancreas of the two peptides increased in parallel during the adaptation to the high protein diet, indicating that these two peptides were under the same control during the adaptation. The concentration and mRNA level of the monitor peptide, which were measured after 0, 3, and 14 days, increased throughout the experiment period, as did the concentration of trypsin. This suggested that the monitor peptide and trypsin may respond to similar signals during the adaptation to a high protein diet and that this apparent coordination may facilitate the adaptation of the pancreas to the diet.     

Association between light exposure at night and manic symptoms in bipolar disorder: cross-sectional analysis of the APPLE cohort

ABSTRACT

Previous studies have found that keeping the room dark at night was associated with a decrease in manic symptoms for patients with bipolar disorder (BD). However, the association between light at night of real-life conditions and manic symptoms is unclear. We investigated the association between bedroom light exposure at night and manic symptoms in BD patients. One-hundred and eighty-four outpatients with BD participated in this cross-sectional study. The average light intensity at night during sleep was evaluated using a portable photometer for seven consecutive nights. Manic symptoms were assessed using the Young Mania Rating Scale (YMRS), and scores ≥5 were treated as a “hypomanic state.” The median (interquartile range) YMRS score was 2.0 (0–5.0), and 52 (28.2%) participants were in a hypomanic state. The prevalence of a hypomanic state was significantly higher in the participants with an average light intensity at night exposure of ≥3 lux than in those with <3 lux (36.7% versus 21.9%; P = .02). In multivariable logistic regression analysis adjusted for BD type, depressive symptoms, sleep duration, and daytime physical activity, the odds ratio (OR) for a hypomanic state was significantly higher for the participants with an average light intensity at night exposure of ≥3 lux than for those with <3 lux (OR: 2.15, 95% confidence interval: 1.09–4.22, P = .02). This association remained significant at the cutoff value of YMRS score ≥6 (OR: 2.51, 95% confidence interval: 1.15–5.46; P = .02). The findings of this study indicate bedroom light exposure at night is significantly associated with manic symptoms in BD patients. Although the results of this cross-sectional investigation do not necessarily imply causality, they may serve to inform beneficial nonpharmacological intervention and personalized treatment of BD patients.     

Diverse effects of insulin-induced hyperpolarization on 3-O-methyl-D-glucose (3-O-MG) transport in frog skeletal muscles

It has been suggested that the insulin-induced hyperpolarization might be a mediator of the stimulatory action of insulin on glucose transport. The purpose of the present study was to investigate the relationship between the insulin-induced hyperpolarization and the stimulatory action of insulin on glucose transport in skeletal muscle. Satorius muscles dissected from bullfrogs (Rana catesbeiana) were used. Insulin induced a hyperpolarization of the membrane and an increase in the 3-O-Methyl-D-glucose (3-O-MG) uptake and extrusion. In the presence of valinomycin, insulin had no significant effect on the membrane potential. Insulin still had the stimulatory action on both the 3-O-MG uptake and extrusion even in the presence of valinomycin, under whose condition insulin had no significant effect on the membrane potential. The magnitude of the stimulatory action of insulin on the 3-O-MG uptake in the presence of valinomycin was smaller than that in the absence of valinomycin. The magnitude of the stimulatory action of insulin on the 3-O-MG extrusion was, on the contrary, larger than that in the absence of valinomycin. The abolishment of the insulin-induced hyperpolarization decreased the 3-O-MG uptake and increased the 3-O-MG extrusion. The observation in the present study concludes that insulin has two different actions on glucose transport. One of them is developed through the insulin-induced hyperpolarization, which increases the 3-O-MG uptake and decreases the 3-O-MG extrusion. The other action is irrelevant of the insulin-induced hyperpolarization and stimulates both the 3-O-MG uptake and extrusion.     

Establishment of primate lymphoblastic cell lines by coculture with a simian T-cell leukemia virus-1 positive, hypoxanthine-guanine-phosphoribosyltransferase negative Japanese macaque cell line

A cell line (JAMH17+) resistant to 8-azaguanine was established from a human T-cell leukemia virus type 1 related virus (simian T-cell leukemia virus-1) positive Japanese macaque cell line. Lymphoblastic cell lines were established from the peripheral blood mononuclear cells of humans, hominoids, and several species of macaques by coculture with JAMH17+ in hypoxanthine-aminopterin-thymidine medium. HTLV-1 specific antigen was detected in some of the established cell lines. Phenotypic analysis showed that several cell lines of crab-eating macaques expressed Leu11a antigen, which is a marker of human natural killer cells.     

Androgenic regulation of epidermal growth factor in the mouse ventral prostate

Castration of adult male mice caused a marked reduction in the amount of immunoreactive epidermal growth factor (EGF) in the ventral prostate, and the treatment of such castrated mice with testosterone increased the EGF level significantly. Gel filtration of prostate extract showed that the immunoreactive EGF in the prostate had the same molecular weight (6,045) as the submandibular gland EGF. Moreover, its isoelectric point (pH 4.5) was almost similar to that (pH 4.55) of the submandibular gland peptide. These results suggest that under the control of androgens, mouse ventral prostate synthesizes EGF structurally and functionally identical to the submandibular gland EGF.     

Cloning, Nucleotide Sequences and Differential Expression of the nifH and nifH-Like (frxC) Genes from the Filamentous Nitrogen-Fixing Cyanobacterium Plectonema boryanum

The frxC gene, found in liverwort chloroplast DNA, encodes aprotein of unknown function. The deduced amino acid sequenceof the protein shows significant homology to that of ni-trogenaseFe-protein encoded by the nifH gene. We have cloned the frxCand nifH genes from the nitrogen-fixing cyanobacterium Plectonemaboryanum, using frxC- and nifH-specific probes, and have determinedtheir nucleotide sequences. The amino acid sequence deducedfrom the frxC gene of P. boryanum exhibits 83% homology to thatof the protein encoded by the/rxCgene from liverwort, whereasit exhibits only 34% homology to that encoded by the nifH genefrom the same organism, namely, P. boryanum. Northern blot analysisshowed that the frxC gene was transcribed more actively undernitrogenase-repressed conditions than under nitrogenase-inducedconditions, suggesting that the FrxC protein has a functiondistinct from nitrogen fixation. These results, together withthe phylogenetic relationship between the nifH and frxC genes,indicate that the frxC and nifH genes are derived from a commonancestral gene but have evolved independently to encode proteinswith different functions. (Received April 27, 1991; Accepted August 12, 1991)     

Changes in synthetic activity of cell walls during the cell cycle in a synchronous culture of Catharanthus roseus

The incorporation rates of [¹⁴C] glucose into various fractions of the cell walls and into the sugar constituent of each fraction were investigated in a synchronous culture of Catharanthus roseus (L.) G. Don in order to elucidate the synthetic aspects of the cell walls during the cell cycle. Changes in the incorporation of radioactivity were closely correlated with changes in the amount of each cell wall fraction as well as with those in sugar composition as reported previously (S. Amino et al. Physiol. Plant. 60: 326–332, 1984). The specific activity of galactose was higher than that of other sugars throughout the cell cycle, and a temporary increase in the incorporation of radioactivity into all cell wall fractions except cellulose was observed just before the increase in cell numbers. The synthetic activities may play key roles in the regulation of cell wall polysaccharide dynamics during the cell cycle.     

Effects of brain and mesenchyme upon the cytogenesis of rat adenohypophysis in vitro

Summary The objective of this in-vitro study was to examine whether the diencephalic floor or the mesenchyme is involved in differentiation of LH cells in the developing rat adenohypophysis. Overall growth of the adenohypophysial tissue was retarded when the adenohypophysial primordium was cultivated after enzymatic removal of the diencephalic floor on days 11.5 and 12.5 of gestation. This malgrowth was more marked when the brain was separated on day 11.5; most expiants retained a simple cystiform structure that consisted of a few layers of undifferentiated cells. Removal of the brain also caused a highly significant decrease (P < 0.001) in the number of immunoreactive LH cells, if it was performed on day 11.5 but not day 12.5. Mesenchyme had little effect on the adenohypophysial growth or the number of immunopositive cells. Cultivation of the adenohypophysial primordium with the diencephalic floor resulted in the appearance of many immunoreactive LH cells. The number of LH cells significantly decreased, however, when the co-cultivated brain completely surrounded the adenohypophysial tissue.These results indicate that in 11.5-day-old fetal rats the diencephalic floor is indispensable for the initial proliferation of adenohypophysial primordial cells and for the early determinating process of LH cells. Once determined, the development of LH cells may proceed without the surrounding tissues. The cytodifferentiation seems to be rather inhibited when in contact with the brain. The significance of the intimate spatial relationship between developing LH cells and the surrounding mesenchyme is also discussed.