Responses of aerial ventilation to hypoxia and hypercapnia inChanna argus,an air-breathing fish

Summary The snake-head fish (Channa argus) is an obligate air-breather inhabiting fresh waters in the temperate zone of East Asia.Ventilation of the air-breathing organ and aerial gas exchange were measured in 1 to 2 kg specimens at 15 and 25°C. Additionally, the ventilatory responses to hypoxia and hypercapnia were studied. Aerial ventilation increased from 1.1 to 2.9 mlbtps·kg^–1·min^–1 when temperature rose from 15 to 25°C. Concomitantly, O₂-uptake through airbreathing increased from 0.1 mlstpd·kg^–1·min^–1 (15°C) to 0.28 mlstpd·kg^–1·min^–1 (25°C), whereas aerial gas exchange was less important for CO₂-climination as evident from low gas exchange ratios (0.16 at 15°C, 0.29 at 25°C).Ventilation increases only slightly in response to inspiration of hypercapnic gas mixtures or to hypoxic conditions in water. By contrast, inspiration of hypoxic gas mixtures caused marked increases of ventilation in particular at the higher temperature.Aerial ventilation inChanna is low compared to values for ectothermic pulmonary breathers. However, its ventilatory responses to hypoxia strikingly resemble those of reptiles: The most marked ventilatory response to hypoxia occurs at the higher temperature where the demands for O₂ are greatest.     

Effects of Some Growth Regulators and Benzoic Acid Derivatives on Flower Initiation and Root Elongation of Pharbitis nil, Strain Kidachi

Seedlings of Pharbitis nil, strain Kidachi, were grown undercontinuous light at 20°C in vessels containing 5,000-mlnutrient solution, 24 plants per vessel. NAA (0.005–0.5µM), GA₃ (0.1–0.5 µM), kinetin (0.5–5µM), benzyladenine (0.05–5 µM) or abscisicacid (4 µM) added to the nutrient solution induced long-dayflowering, and the flowering was always accompanied by suppressionof root elongation. 3,4-Dichlorobenzoic acid (0.05–10µM) and some other benzoic acid derivatives which arehighly effective for the induction of flowering in Lemna paucicostataalso showed similar effects. Neither NAA, kinetin nor 3,4-dichlorobenzoicacid applied via the apical part of the hypocotyl could causeflowering or suppression of root elongation. Thus, the flower-inducingeffect of the above substances was presumed to be secondaryto the suppression of root elongation. Ethrel (1–50 µM)added to the nutrient solution suppressed root elongation, butdid not induce flowering probably because it has flower-inhibitingactivity. ¹ This paper is dedicated to the memory of Dr. Joji Ashida,the first president of the Japanese Society of Plant Physiologists. (Received December 15, 1982; Accepted February 25, 1983)     

Evidence that cyclic AMP may regulate Ca2+-mobilization and phospholipases in thrombin-stimulated human platelets

The regulation of human platelet responses by cyclic AMP (cAMP) has been investigated by measuring thrombin-stimulated serotonin release, Ca²⁺ uptake and phospholipase activity. Thrombin-induced 1,2-diacylglycerol (DG) formation as a result of phospholipase C activation was inhibited by pretreatment with dibutyryl cAMP (dbcAMP) in a dose-dependent manner. Subsequent failure to produce phosphatidic acid (PA), which is converted from 1,2-DG by phosphorylation and would serve as intracellular Ca²⁺ ionophore, appeared to parallel the decrease in Ca²⁺ uptake activity. Phospholipase A₂ activity, monitored by the production of [³H]lysophosphatidylcholine and [³H]lysophosphatidylethanolamine, was also suppressed by dbcAMP. These data indicate that the intracellular cAMP level may be closely associated with Ca²⁺ uptake and phospholipases activation. In addition, it is suggested that alteration of intracellular cAMP regulates phospholipase activation and consequently platelet responses, perhaps by controlling available Ca²⁺ content.     

Glucose catabolism during aging and differentiation in hypocotyls ofPhaseolus mungo seedlings

Changes in activities of the glycolytic and pentose phosphate (PP) pathways in glucose catabolism in various parts of the hypocotyls obtained from 4-day-old etiolatedPhaseolus mungo seedlings were investigated by measuring the inhibition rates of respiration by iodoacetate and malonate, and the release of¹⁴CO₂ from [1-¹⁴C]- and [6-¹⁴C]glucose. The relative activity of the PP pathway in glucose catabolism was higher in the immature part (Part I) and the aged part (Part V) of the hypocotyls than in the intermediary one (Part III), while the activity of the glycolytic pathway decreased with aging. On a fresh weight basis, the enzyme activities of the glycolytic and PP pathways were higher in Part I than in Parts III and V. On a protein content basis, however, activities of the enzymes of the PP pathway increased with aging and differentiation of the hypocotyls whereas those of the glycolytic pathway decreased. Levels of nicotinamide adenine nucleotides were found to be in the following order: Part I>Part III> Part V for NAD⁺+NADH; Part I>Part V>Part III for NADP⁺+NADPH. The stimulative effect of methylene blue on decreasing the C₆/C₁ ratio was greater in Part III than in Part I, and No effect was observed in Part V. These data suggest that a decrease in the activity of the glycolytic pathway with aging and differentiation may be due to the decreasing glycolytic enzyme activities and NAD(H) content. The higher activity of the PP pathway in the immature part is attributable to larger amounts of NADP(H) and enzymes of the PP pathway. The greater contribution of the PP pathway to glucose catabolism in the aged part than in the intermediary part seems to results from a more active turnover of NADP and the relatively higher activity of the enzymes of the PP pathway than those of the glycolytic pathway.     

Establishment of five human myeloma cell lines

Summary Five human myeloma cell lines, KMM-1, KMS-5, KMS-11, KMS-12- PE, and KMS-12-BM, have been established at Kawasaki Medical School since 1980. As the KMS-12-PE and KMS-12-BM lines were obtained from the same patient, these five cell lines have been derived from four patients with multiple myeloma. The five myeloma cell lines are stably growing at present in RPMI 1640 medium supplemented with 10% fetal bovine serum. They can also grow in a defined culture medium without serum. That these cell lines were, human myeloma cells was confirmed by the following findings. Ultranstructually, all five cell lines showed features characteristic of plasma cells. KMM-1 and KMS-11 cells secreted lambda and kappa chains into the culture medium, respectively, but the other cell lines produced no immunoglobulins. KMM-1 expressed cytoplasmic lambda antigen, KMS-5 showed cytoplasmic delta, and KMS-11 expressed surface kappa, whereas KMS-12-PE and KMS-12-BM cells showed no surface or cytoplasmic immunoglobulins. Regarding reaction with a monoclonal plasma cell antibody (PCA-1), four of the five lines were positive, the exception being KMS-5. Another monoclonal antibody (CD38), which also recognizes plasma cells, reponded to KMM-1, KMS-12-PE, and KSM-12-BM. KMS-5 cells expressed acute lymphoblastic leukemia antigens (CALLA). These data suggest that such lines as KMM-1, KMS-11, KMS-12-PE, and KMS-12-BM represent later stages of B-cell differentiation, and that KMS-5 represents a relatively early stage of B-cell differentiation. All the cell lines lacked Epstein-Barr virus nuclear antigen, showed abnormal karyotypes of human origin, and differed from each other in the isozyme patterns examined. Only KMS-5 was tumorigenic when transplanted subcutaneously into nude mice.     

Membrane Viscosity Correlates with α1-Adrenergic Signal Transduction of the Aged Rat Cerebral Cortex

We investigated, using adult (2-month-old) and senescent (12- and 24-month-old) rats, the effects of aging on the relationship between the alpha 1-adrenergic coupling system and the membrane viscosity of the cerebral cortex. There was no age-related difference in the KD values of [3H]prazosin binding on the membranes. The Bmax values of [3H]prazosin binding were reduced with advanced age. Norepinephrine-induced formation of 3H-labeled inositol phosphates (3H-IPs) in the slices increased with advanced age. The EC50 values for norepinephrine to stimulate the formation of 3H-IPs at advanced age were lower than that at adult age. The cholesterol content in membranes increased with advanced age. No changes in the phospholipid content in membranes were observed with advanced age. Concomitantly, an increase of the molar ratio of cholesterol to phospholipids was observed with advanced age. The membrane viscosity as measured by 1,6-diphenyl-1,3,5-hexatriene increased with advanced age. These results indicate that the altered cholesterol content and/or viscosity in cortical membranes of the aged rat may account for the loss of alpha 1-adrenergic receptor density and/or compensatory changes in the receptor-phospholipase C coupling system.     

Isolation of Glutamyltaurine from Bovine Brains and Proof of Its γ-Linkage by the B/E Linked Scan SIMS Technique

We isolated a glutamyltaurine from bovine brains and determined its structure as gamma-glutamyltaurine (gamma-Glu-Tau; glutaurine) by use of a new mass spectrometric technique [B/E linked scan sputtered ion mass spectrometry (SIMS)], which we have recently shown to be useful for distinguishing the gamma- from the alpha-isomer of glutamyl-dipeptides. Neither the alpha-isomer of glutamyltaurine nor any aspartyltaurines could be detected in bovine brain.     

Synthesis of protein and mRNA is necessary for transition of suspension-cultured Catharanthus roseus cells from the G1 to the S phase of the cell cycle

The effects of inhibition of the synthesis of protein, mRNA or rRNA on the progression of the cell cycle have been analyzed in cultures of Catharanthus roseus in which cells were induced to divide in synchrony by the double phosphate starvation method. The partial inhibition of protein synthesis at the G₁ phase by anisoniycio or cycloheximide caused the arrest of cells in the G₁ phase or delayed the entry of cells into the S phase. When protein synthesis was partially inhibited at the S phase, cell division occurred to about the same extent as in the control. When asynchronously dividing cells were treated with cycloheximide, cells accumulated in the G₁ phase, as shown by flow-cytometric analysis. The partial inhibition of mRNA synthesis by α-amanitin at the G₁ phase caused the arrest of cells in the G₁ phase, although partial inhibition of mRNA synthesis at the S phase had little effect on cell division. In the case of inhibition of synthesis of rRNA by actinomycin D at the G₁ phase, initiation of DNA synthesis was observed, but no subsequent DNA synthesis or the division of cells occurred. However, the addition of actinomycin D during the S phase had no effect on cell division. These results suggest that specific protein(s), required for the progression of the cell cycle, are synthesized in the G₁ phase, and that the mRNA(s) that encode these proteins are also synthesized at the G₁ phase.     

An endoprotease homologous to the blood clotting factor X as a determinant of viral tropism in chick embryo.

Host cell proteases responsible for activation of viral fusion glycoproteins are an important determinant for spread and tropism of various animal viruses. Exemplifying such proteases for the first time, we isolated an endoprotease from chick embryo, that activates para- and orthomyxovirus fusion glycoproteins by cleaving their precursor proteins at a specific, single arginine site. The protease is a calcium dependent serine protease consisting of two subunits, the 33 kd catalytic chain and the 23 kd chain possibly required for Ca2+ binding, and was found to be highly homologous, if not identical, to the blood clotting factor X(FX), a member of the prothrombin family. Its high efficiency and specificity in cleavage reactions was attributable to the properties characteristic of FX. Its role in vivo was strongly supported by cleavage inhibition in ovo highly selective for this virus group with a specific peptide inhibitor against FX.