Biological effects of exposure to high frequency electromagnetics on rabbits and guinea pigs]

To investigate the biological effects of exposure to feeble high frequency electromagnetism, skin surface temperature, blood vessel (arterioles and venules) diameter were examined, using infrared thermography, a laser doppler flowmeter, and a video microscope, respectively, in the ear of rabbits. After exposing the ear of rabbits to high frequency electromagnetism value of 9 MHz for 15 minutes, continued rising of local temperature was demonstrated. Though dilatation of arterioles was not seen. In addition, venules tended to dilate and blood flow also to increase, and microcirculation was accelerated at the site where electromagnetism was exposed. Hazardous effects of long term exposures of high frequency electromagnetism (9 MHz for 30 days, 8 hours/day) on guinea pigs were not observed in their behavior, food consumption, body and organ weights, hematological and biochemical values, macroscopic and microscopic findings on autopsy.     

Changes in the lysosome structure during the formation of zoospores inTrebouxia potteri

Summary Changes in the lysosome structures were examined by electron microscopy during the formation of zoospores inTrebouxia potteri. Lysosomes in vegetative cells were homogeneously filled with electron-dense material. At the beginning of zoospore formation, lysosomes invaginated or evaginated to take up mitochondria, ER, or cytoplasmic ground plasma. The ingested organelles became disorganized within the lysosomes. During this disruption of these organelles, the lysosomal contents became heterogeneous, suggesting a decrease in the amount of enzymes within the lysosomes. Golgi bodies and ER seemed to be involved with the disruption of the organelles, probably supplying some substances necessary for the functioning of the lysosomes. Amount of electron-dense materials decreased and, finally, only one to three small spherical aggregates remained in the lysosomes. Then the lysosomes appeared to shrink via loss of watery substances or cutting off of electron-transparent regions. After these changes in lysosome structure, nuclei started to divide successively for formation of the zoospores. The possibility is proposed that the drastic cytoplasmic changes operated by lysosomes trigger the following morphogenetic events in the formation of zoospores.Abbreviations ER endoplasmic reticulum - TGN trans Golgi network     

Relationship of actin organization to growth in the two forms of the dimorphic yeastCandida tropicalis

Summary Candida tropicalis is a dimorphic yeast capable of growing both as a budding yeast and as filamentous hyphae depending upon the source of the carbon used in the culture medium. The organization of F-actin during growth of the yeast form (Y-form) and the hyphal form (H-form) was visualized by rhodamine-conjugated phalloidin by using a conventional fluorescence microscope as well as a laser scanning confocal fluorescence microscope. In single cells without a bud or non-growing hyphae, actin dots were evenly distributed throughout the cytoplasm. Before the growth of the bud or hypha, the actin dots were concentrated at one site. During bud growth, actin dots were located solely in the bud. They filled the small bud and then filled the apical two-thirds of the cytoplasm of the middlesized bud. During growth of the large bud, actin dots which had filled the apical half of the cytoplasm gradually moved to the tip of the bud. In the formation of the septum, actin dots were arranged in two lines at the conjunction of the bud and the mother cell. During hyphal growth, the majority of actin dots were concentrated at the hyphal apex. A line of clustered spots or a band of actin was observed only at the site where the formation of a new septum was imminent. This spatial and temporal organization of actin in both categories of cells was demonstrated to be closely related to the growth and local deposition of new cell wall material by monitoring the mode of growth with Calcofluor staining. Treatment of both forms of cells with cytochalasin A (CA) confirmed the close relationship between actin and new cell wall deposition. CA treatment revealed lightly stained unlocalized actin which was associated with abnormal cell wall deposition as well as changes in morphology. These results suggest that actin is required for proper growth and proper deposition of cell wall material and also for maintaining the morphology of both forms of cells.Abbrevations FM fluorescence microscopy - EM electron microscopy - rh rhodamine - CA cytochalasin A - CD cytochalasin D - PBS phosphate-buffered saline - DMSO dimethylsulfoxide - GA glutaraldehyde     

L-lactate production from xylose employingLactococcus lactis IO-1

Summary The growth, substrate utilisation and L-lactate production ofLactococcus lactis IO-1 were examined on xylose, and glucose and xylose media. The yield of lactate on xylose was 0.47 g lactate/g xylose at an initial xylose concentration of 51.2 g/l and the _max was 0.72 h^–1. Xylose cultures were more susceptible to lactate inhibition than were glucose cultures but showed similar kinetic behaviour. The organism was capable of complete sugar utilisation when grown on a mixture of 20 g/l xylose and 20 g/l glucose and synthesised 0.66 g lactate/g sugar.     

Onset of the constrictive effect of indomethacin on the ductus arteriosus in fetal rats.

The time of onset of the constrictive effect of indomethacin on the ductus arteriosus (DA) in fetal rats was assessed by measurement of the caliber of the DA after maternal treatment with indomethacin on days 19-21 of gestation. The day following overnight mating was regarded as day 0 of gestation. Observation was performed by direct exposure of the DA by hand shaving of intact frozen fetuses. On days 20 and 21, the DA was significantly constricted 3 h after maternal treatment with 1 mg/kg of indomethacin. When the DA was examined at 19 1/2 and 19 2/3 days of gestation (3 h after indomethacin exposure), it was significantly constricted at 19 2/3 days but not at 19 1/2 days. Higher doses of indomethacin (10 and 100 mg/kg) induced a significant constriction of the DA at day 19 1/2, but not at the beginning of the same day (1.00 a.m.). These results suggest that the onset of the susceptibility of the DA to the constrictive effect of indomethacin occurs in the first half of day 19 of gestation.     

Distribution and characterization of immunoreactive porcine C-type natriuretic peptide.

C-type natriuretic peptide (CNP) is a new member of the natriuretic peptide family recently identified in porcine brain (1). We raised an antiserum against porcine CNP and set up a radioimmunoassay (RIA) for CNP. Using this RIA system, distribution of immunoreactive (ir-) CNP in porcine tissue was measured and compared with that of ir-atrial natriuretic peptide (ANP) and ir-brain natriuretic peptide (BNP). Tissue concentration of ir-CNP in brain was the highest of the three natriuretic peptides at about 0.79 pmol/g wet wt. CNP was present in medulla-pons in high concentration, with a significant concentration detected in cerebellum. In contrast, ir-CNP was not detected in peripheral tissue, including heart, in a significant concentration. These data demonstrated sharp contrasts in the distribution of the three natriuretic peptides, suggesting that CNP is a natriuretic peptide functioning in the central nervous system.     

X-ray crystallographic conformational study of 5'-O-[N-(L-alanyl)-sulfamoyl]adenosine, a substrate analogue for alanyl-tRNA synthetase

In order to elucidate the substrate specificity of alanyl-tRNA synthetase, 5'-O-[N-(L-alanyl)sulfamoyl]adenosine (Ala-SA), an analogue of alanyl-AMP, was chemically synthesized. Its binding ability is similar to that of the substrate based on the inhibitory activity for the aminoacylation of alanyl-tRNA synthetase. Taking advantage of the stable sulfamoyl bond of Ala-Sa, compared with the highly labile aminoacyl bond of alanyl-AMP, the molecular conformation of the former inhibitor was studied by X-ray single crystal analysis. Crystal data are as follows: C13H19N7O7S.2H2O, space group C2, a = 39.620(6), b = 5.757(1), c = 20.040(3) A, beta = 117.2(1) degrees, V = 4065(9) A3, Z = 8, and final R = 0.065 for 2785 independent reflections of F(2)0 greater than or equal to 2 sigma (F0)2. In the crystal, the molecule is in a zwitterionic state with the terminal amino group protonated and sulfamoyl group deprotonated, and takes an open conformation, where the L-alanine moiety is located far from the adenosine moiety with gauche/trans and trans orientations about the exocyclic C(4')-C(5') and C(5')-O(5') bonds, respectively. The conformation of the adenosine moiety is anti for the glycosyl bond and C(3')-endo for the ribose puckering, and alanine is in the usually observed trans region for the psi torsion angle. The molecular dimensions of the sulfamoyl group are nearly the same as those of the phosphate group. The biological significance of the observed Ala-SA conformation is discussed in relation with the molecular conformation of tyrosyl-AMP complexed with tyrosyl-tRNA synthetase.     

Simple in vivo bioassay without radioisotopes for recombinant human erythropoietins.

A simple in vivo bioassay suitable for routine testing of quality control of recombinant human erythropoietin (rHuEPO) analogues was developed. The assay took four days, normal mice were used and radioactive compounds were not needed. EPO activity was measured by the increased number of some part of reticulocytes which increased specifically and dose-dependently by the injection of rHuEPO. They were considered to be mostly immature reticulocytes and were counted as the residual particles from blood cells after treatment with a hemolysing reagent. These particles could be counted by conventional automated microcell counters. The assay procedure was simple and easy. The sensitivity, reliability and reproducibility of this method were acceptable for routine in vivo bioassay of rHuEPOs. This method was economical, and can be used instead of the existing bioassays for rHuEPOs.     

Inhibition of poly(ADP-ribose) synthetase by unsaturated fatty acids, vitamins and vitamin-like substances

Various vitamins and vitamin-like substances inhibited the activity of poly(ADP-ribose) synthetase in vitro. The most potent were essential fatty acids, i.e. arachidonic acid, linoleic acid, and linolenic acid; their 50% inhibitory concentrations (IC50) were 44-110 microM, indicating a higher potency than nicotinamide, a well-known vitamin inhibitor (IC50 = 210 microM). Vitamins K3, K1, and retinal were the next strongest inhibitors, followed by alpha-lipoic acid, coenzyme Q0, and pyridoxal 5-phosphate. Nicotinamide and vitamin K3 exhibited mixed-type inhibition with respect to NAD+, while arachidonic acid exhibited dual inhibitions, competitive at 50 microM and mixed-type at 100 microM.     

Peroxisomal isocitrate lyase of the n-alkane-assimilating yeast Candida tropicalis: gene analysis and characterization

A genomic DNA clone encoding isocitrate lyase, a key enzyme of the glyoxylate cycle and a peroxisomal enzyme of the n-alkane-assimilating yeast Candida tropicalis has been isolated with a cDNA probe from the yeast lambda EMBL library. Nucleotide sequence analysis of the genomic DNA clone disclosed that the region coding isocitrate lyase had a length of 1,650 base pairs, corresponding to 550 amino acids (61,602 Da). RNA blot analysis demonstrated that only one kind of mRNA (2 kb) supposed to be transcribed from this gene was present in the cells. A comparison of the amino acid sequences was made with the isocitrate lyase of castor bean, one of the glyoxysomal enzymes, and the enzyme of E. coli. The isocitrate lyases of C. tropicalis and castor bean had high homology, and the presence of some amino acid stretches conserved in all three enzymes suggests that these might be involved in the catalysis of the common reaction. There was an insertion common to the isocitrate lyases of C. tropicalis and castor bean, which is of interest concerning their evolution. In the C-terminal region, a characteristic sequence similar to that previously proposed as the import signal to peroxisomes was present.