Differences in Ca2+ mobilization induced by alpha-adrenergic agonist and phosphatidic acid in cultured hepatocytes

In an attempt to elucidate the relationship between phosphatidylinositol breakdown and alpha-adrenergic responses, effects of phosphatidic acid and phosphatidylinositol related metabolites on Ca²⁺ mobilization and glucose output in cultured hepatocytes were examined. Norepinephrine induced the net ⁴⁵Ca²⁺ efflux from preloaded cells and stimulated glucose output via alpha-adrenergic receptor stimulation, whereas phosphatidic acid caused ⁴⁵Ca²⁺ uptake to cells and did not stimulate glucose output. Myo-inositol-monophosphate, diglyceride and arachidonic acid, which are released by phosphatidylinositol breakdown, had no effect on ⁴⁵Ca²⁺ efflux and glucose output in cells. These results suggest that phosphatidic acid and phosphatidylinositol related metabolites can not mimic the alpha-adrenergic actions in cultured hepatocytes.     

Chromosomal location of the Escherichia coli cytochrome b556 gene, cybA

Summary The amounts of cytochrome b556 in the cytoplasmic membranes of several Escherichia coli K12 strains having F-prime factors and a lambda transducing phage were determined. The amount was amplified about two-fold in strains having F100-12 and F152, but not in strains having F100-11, F8 and psu ⁺ 2glnS ⁺. The strain TK3D11, which lacks the kdp-gltA region (deletion D-01) of the E. coli chromosome, did not synthesize cytochrome b556 at all. From these results, the gene cybA encoding cytochrome b556 was located in the kdp-gltA region.In the cytochrome b556-deficient mutant, a novel b type cytochrome, cytochrome b561 which is a product of the gene cybB, was identified. It seems to function as a physiological electron transferring cytochrome in place of cytochrome b556 in this mutant.Abbeviations HPLC high performance liquid chromatography - EDTA ethylenediamine tetraacetic acid - SDS sodium dodecyl sulfate - NADH reduced form of nicotinamide adenine dinucleotide     

Changes in the activity of enzymes involved in purine "salvage" and nucleic acid degradation during the growth of Catharanthus roseus cells in suspension culture

Changes during growth in the activity of several enzymes involved in purine "salvage", adenine phosphoribosyltransferase (EC 2.4.2.7), guanine phosphoribosyl-transferase (EC 2.4.2.8), hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) and adenosine kinase (EC 2.7.1.20), the enzymes which catalyze the conversion of nucleoside monophosphate to triphosphate, nucleoside monophosphate kinase (EC 2.7.4.4) and nucleoside diphosphate kinase (EC 2.7.4.6), and several degradation enzymes, deoxyribonucleae(s), ribonuclease(s). phosphatase(s), nucleosidase (EC 3.2.2.1), 3'-nucleotidase (EC 3.1.3.6) and 5'-nucleotidase (EC 3.1.3.5) were examined in cells of Catharanthus roseus (L.) G. Don cultured in suspension. In addition, the incorporation of [8-¹⁴C] adenine, [8-¹⁴C] adenine, [8-¹⁴C]hypoxanthine. [8-¹⁴C] adenosine and [8-¹⁴C]inosine into nucleotides and nucleic acids was also determined using intact cells.
The activities of all purine "salvage" enzymes examined and those of nucleoside monophosphate and diphosphate kinases increased rapidly during the lag phase and decreased during the following cell division and cell expansion phases. The rate of incorporation of adenine, guanine, hypoxanthine, and adenosine into nucleotides and nucleic acids was higher in the lag phase cells than during the following three phases. The highest rate of [8-¹⁴C]inosine incorporation was observed in the stationary phase cells. The activity of all degradation enzymes examined decreased when the stationary phase cells were transferred to a new medium.
These results indicated that the increased activity of purine "salvage" enzymes observed in the lag phase cells may contribute to an active purine "salvage" which is required to initiate a subsequent cell division.     

Respiration and avoidance reaction of a cyprinid fishPseudogobio esocinus under hypoxia

A cyprinid fish,Pseudogobio esocinus showed gradual bradycardia at oxygen saturation (%) of less than 29.7±4.6 (1.89±0.29 ml/l of oxygen concentration), surfacing at 14.7±1.3 (0.94±0.09ml/l), drastic decrease of oxygen consumption at less than 14.2±0.8 (0.91 ±0.06ml/l) and asphyxia at 9.7±1.4 (0.62±0.09ml/l). The fish avoided water having low oxygen saturation of less than 54.0± 5.4 (3.38±0.30ml/l), and markedly at less than 26.2±3.4 (1.62±0.16 ml/l).     

Glucagon-related peptides in the rat hypothalamus

Summary Immunohistochemically, nerve fibers and terminals reacting with anti-N-terminal-specific but not with anti-C-terminal-specific glucagon antiserum were observed in the following rat hypothalamic regions: paraventricular nucleus, supraoptic nucleus, anterior hypothalamus, arcuate nucleus, ventromedial hypothalamic nucleus and median eminence. Few fibers and terminals were demonstrated in the lateral hypothalamic area and dorsomedial hypothalamic nucleus. Radioimmunoassay data indicated that the concentration of gut glucagon-like immunoreactivity was higher in the ventromedial nucleus than in the lateral hypothalamic area. In food-deprived conditions, this concentration increased in both these parts. This was also verified in immunostained preparations in which a marked enhancement of gut glucagon-like immunoreactivity-containing fibers and terminals was observed in many hypothalamic regions. Several immunoreactive cell bodies were found in the ventromedial and arcuate nuclei of starved rats. Both biochemical and morphological data suggest that glucagon-related peptides may act as neurotransmitters or neuromodulators in the hypothalamus and may be involved in the central regulatory mechanism related to feeding behavior and energy metabolism.     

The endosome-lysosome system in the absorptive cells of goldfish hindgut

Summary The vacuolar system in the absorptive cells of the goldfish hindgut was studied by rapid freeze-substituted and cytochemical techniques. The apical cytoplasm of the absorptive cells contained two types of vacuoles: endosomes and lysosomes. The former were characterized by an absence of acid phosphatase activity, a dot-like distribution of material at the peripheral rim, the labelling of the inner surface with horseradish peroxidase (HRP), and by frequent connections to cytoplasmic tubules (CT), which were also free of acid phosphatase activity. The latter vacuole was preferentially located in the deeper cytoplasm and was characterized by the presence of acid phosphatase activity, an electron-dense interior matrix, a peripheral electron-lucent region (a halo), and by the detachment of HRP from the inner surface. Connections between CTs and these latter vacuoles were rarely seen. In the deeper cytoplasm, fusion between endosomes and lysosomes was sometimes observed. These results suggest that the vacuoles which are associated with CTs are endosomes, but not lysosomes, and that internalized materials are transported through the endosome-lysosome system to a giant food vacuole in the cell.     

“SIF” cells in the sympathetic ganglia of the bullfrog,Rana catesbeiana: variety in population and innervation

Summary Small intensely fluorescent (SIF) cells appeared singly or, more frequently, in variably-sized clusters in the sacroccygeal 8th and 9th sympathetic ganglia of the bullfrog. Smaller clusters containing only two to nine SIF cells accounted for 61% of 1773 clusters examined. The largest cluster contained 283 cells. The number of cells in individual ganglia also varied from 21 to 3332. SIF cells, solitary as well as in smaller clusters, received no distinct form of the synaptic contact. In contrast, the cells in larger clusters were frequently innervated by nerve endings that were similar in vesicular constitution to the nerve endings on principal ganglion (PG) cells. No synaptic contact was found between SIF cells and PG cells. SIF cells were also characterized by their location in the vicinity of blood capillaries with a continuous endothelium. p]Our observation seems to suggest that larger clusters of SIF cells receiving nerve endings are linked to a paracrine and/or endocrine system. Chemical influence via the blood stream and intraganglionic milieu for non-innervated SIF cells in the solitary or smaller clusters is a subject for speculation. An interneuronal role of SIF cells to relay stimuli to PG cells seems unlikely. The possible functions here assigned to SIF cells could be variable in efficiency depending on their population and density.     

Disorganization of stroma alters epithelial differentiation of the glandular stomach in adult mice

Summary The response of adult epithelium in contact with heterologous mesenchymes/stromas was studied in three digestive organs (forestomach, glandular stomach, and duodenum). After various tissues were implanted beneath the epithelial layer of adult mice, the epithelial differentiation was examined after sacrifice of animals at intervals up to 24 weeks. In the forestomach and duodenum, the epithelial differentiation was not affected at all by the tissue implantation. In the glandular stomach, in contrast, epithelial cells exhibited altered differentiation in which chief and parietal cells disappeared and were replaced by columnar epithelial cells with PAS-positive granules. These epithelial cells often formed immature villi. Such differentiation-altered columnar epithelium (DACE) was induced by implanting any type of tissue and even by sham operation, indicating that it was induced by disorganization of the tissue-implanted stroma. The size of DACE was significantly influenced by the stage of implanted tissue; 14.5-day fetal mesenchyme induced the largest DACE, and was followed by 16.5-day fetal mesenchyme, adult stroma, and sham operation. These results suggest the importance of stromal organization in maintaining epithelial differentiation in the glandular stomach.     

Enhanced susceptibility of target KMT-17 cells to activated macrophages by treatment with the antitumor agent bleomycin

Summary We observed that after KMT-17 cells had been treated with bleomycin (BLM), even with a dose as high as 160 g/ml, they were still able to form colonies in soft agar. We then studied the susceptibility of KMT-17 cells treated with BLM to activated macrophages. During a colony inhibition assay, BLM-treated KMT-17 cells were found to be much more susceptile to activated macrophages than nontreated KMT-17 cells, moreover, a tumor neutralizing assay showed that the growth of BLM-treated KMT-17 cells was also significantly inhibited by activated macrophages as compared with nontreated KMT-17 cells. Macrophages activated by both BLM and the Nocardia rubra cell wall skeleton were able to mediate such tumor inhibition activity in BLM-treated KMT-17 cells. Activated macrophages did not seem to have strong antitumor activity against nontreated KMT-17 cells in vivo, however, the life span of the rats which were inoculated i. p. with KMT-17 cells was significantly expanded after the tumorbearing rats were given BLM i.p. The data presented here suggest that not only does BLM have a direct tumoricidal effect on KMT-17 cells, it also regulates immunosensitivity of targets to immune effectors. We also discuss the mechanism for enhancing the susceptibility of KMT-17 cells to activated macrophages brought about by treatment with BLM.Supported in part by a Grant-in-Aid for Cancer Research from the Japanese Ministry of Education, Science, and Culture