Analysis of mutations introduced into the chromosomal immunoglobulin μ gene

We have introduced a pSV2neo-derived vector that contains a 2-base-pair (bp) deletion in its immunoglobulin gene constant region into hybridoma cells bearing a single copy of the wild-type chromosomal immunoglobulin gene. Homologous recombination between the transferred mutant C region and the wild-type chromosomal C region is expected to introduce the 2-bp deletion into the chromosomal gene, generating recombinant cells synthesizing noncytolytic IgM. Analysis of the DNA in independent noncytolytic transformants indicates that in one case the gene has the structure expected for correct homologous recombination. Unexpectedly, the remaining transformants, bear chromosomal gene deletions.     

Tissue blood flow and localization of arteriovenous anastomoses in pigs with microspheres of four different sizes

Using microspheres of 10, 15, 25 and 35 m diameters we have compared blood flows to a large number of tissues and the complete distribution of common carotid arterial blood in an attempt to localize the site of arteriovenous shunting in anaesthetized pigs. Blood flow values obtained with the spheres of the four sizes were similar in the brain, heart, kidneys, skeletal muscles, stomach, small and large intestines, spleen, adrenals, liver, bones, fat and salivary glands. In the ears and skin from several regions, blood flow measured with 35 m spheres was substantially higher than those measured with smaller spheres. Blood flow pattern in the eye and tongue was such that 10 m flow value was moderately less and the 25 and 35 m values were only slightly higher than the corresponding 15 m value. These data indicate that a considerable number of arteriovenous anastomoses, large enough to let microspheres of up to 25 m pass through, are present in the ears and skin. Only smaller arteriovenous anastomoses may be present in the eyes and tongue. This conclusion is supported by the observation that 5-hydroxytryptamine, which causes constriction of arteriovenous anastomoses, negated the difference in the blood flows measured with 15 and 35 m spheres in the ears and skin.This study was supported by a grant from Bayer AG, Wuppertal, FRG     

In vitro activity of the aryl-fluoroquinolones A-56619 and A-56620 and evaluation of disk susceptibility tests

The activity of two new quinolones, A-56619 and A-56620, was compared in vitro to that of norfloxacin and ciprofloxacin against 6,699 bacterial isolates in four separate clinical laboratories. The overall percentage of strains susceptible to designated concentrations were as follows: 99.1% for norfloxacin (MIC4.0 g/ml), 96.1% for ciprofloxacin (MIC1.0 g/ml), 96.8% for A-56620 (MIC 2.0 g/ml) and 96.1% for A-56619 (MIC 4.0 g/ml). For disk diffusion susceptibility tests 10 g A-56619 disks are tentatively recommended with interpretive standards of 18mm for susceptibility and 13mm for resistance; 5 g A-56620 disks may be used with tentative standards of 19mm for susceptibility and 14mm for resistance.     

Effect of steroids on γ-aminobutyrate-induced currents in cultured rat astrocytes

Cultured astrocytes from rat cortex respond to the inhibitory neurotransmitter -aminobutyric acid (GABA) by the activation of Cl^– channels [Bormann J, Kettenmann H (1988) Proc Natl Acad Sci USA 85:9336–9340]. The glial response shares many pharmacological properties with those mediated by neuronal GABA_A receptors, but differs in its sensitivity to inverse benzodiazepine agonists [Backus KH, Kettenmann H, Schachner M (1988) Glia 1:132–140]. To compare glial GABA receptors further with their neuronal counterparts, we analysed the effect of steroids, which have recently been shown to modulate neuronal GABA_A-receptor-mediated responses, on GABA-induced currents in astrocytes. The agonist allotetrahydrodeoxycorticosterone (THDOC) at concentrations of 100 nM and 1 M enhanced GABA-evoked (with 10 M GABA) currents up to 115% and 162.4% of controls respectively. The antagonist dehydroisoandrosterone 3-sulphate (DHEAS) at concentrations of 1 M, 10 M and 100 M depressed GABA-evoked (10 M) currents to 72%, 42.8% and 21.4% of controls respectively. The steroids were less effective at higher GABA concentrations. 100 M DHEAS directly elicited a membrane current, while THDOC (1 M) did not exert any direct response. This study demonstrates that steroids modulate GABA-evoked currents and thus may interfere with any of the functions of glial GABA receptors that are at present under discussion.     

Criteria for testing the susceptibility ofStreptococcus pneumoniae to cefotaxime and its desacetyl metabolite using 1 μg or 30 μg cefotaxime disks

In vitro susceptibility tests were performed with 350 selected strains ofStreptococcus pneumoniae to evaluate disk diffusion tests with 30 g and 1 g cefotaxime disks. Zones were compared to MICs of cefotaxime with and without its desacetyl metabolite. Cefotaxime was two to eight times more active than desacetyl cefotaxime, but the two compounds were additive when combined in vitro. For 30 g disks, zone size breakpoints were 27 mm, 28–30 mm and 31 mm for resistant, intermediate and susceptible, respectively. For 1 g disks, those zone size criteria were reduced to 13 mm, 14–16 mm and 17 mm. The 30 g disk that is currently available for testing other species can be used for testing pneumococci; however, the 1 g disk has some important advantages.     

Über die ultrarote Beugungsoptik des quergestreiften Muskels

Zusammenfassung Photographisch-photometrisch mit infrarotempfindlichem Aufnahmematerial und lichtelektrisch-ultrarotspektralphotometrisch mit Hilfe von PbS-Zellenanordnungen wurde das beugungsoptische Verhalten isolierter, überlebender, parallelfaseriger quergestreifter Muskeln des Frosches untersucht.Photographisch wurden Beugungsspektren bis =1,05 registriert, lichtelektrisch betrug die langwellige Beugungsnachweisgrenze =1,82 .Die photographisch-photometrischen Meßwerte gestatten die Berechnung der Gitterkonstanten des Skeletmuskels. Sie beträgt auf Grund der Photogrammetrie im Mittel 2,87 .Der Mittelwert für die Gitterkonstante auf Grund der lichtelektrisch-ultrarotspektrophotometrischen Messungen beträgt 2,89 . Damit befinden sich diese Werte in sehr guter Übereinstimmung mit den visuellmikroskopischen und sichtbarbeugungsoptischen Ergebnissen. Bemerkenswert ist ihre überindividuelle Konstanz.In der Diskussion wird auf die Erklärung der Abweichung der tatsächlichen langwelligen von der theoretischen Beugungsgrenze eingegangen und auf Grund der Meßwerte auf die Rolle der Absorptions-zunahme im Wellenlängengebiet oberhalb 1,82 , aber ebenso auch auf die Möglichkeit des Anisotropieverlustes im Ultrarot hingewiesen.Mit 3 Textabbildungen     

Inhibitory effect of phloretin on histamine release from isolated rat mast cells

The ability of the flavonoid phloretin to inhibit histamine release from rat mast cells varied considerably with the releasing agent investigated. The response to the combination of the ionophore A23187 and the phorbol ester TPA and to suboptimal concentrations of the ionophore (0.5 M) was potently inhibited (IC₅₀ about 5 M), whereas phloretin was less potent against responses to the ionophore (1 M) IC₅₀ of 17 M), to antigen alone and in combination with TPA (IC₅₀ of 30–50 M), to TPA in the absence of calcium (IC₅₀ of 50 M) and to compound 48/80 in the absence and presence of calcium (IC₅₀ of 60–90 M). The inhibition by phloretin at concentrations above 10M was partly counteracted by glucose (5 mM) indicating effects on oxidative metabolism. The flavonoid quercetin was equally potent in inhibiting histamine release induced by antigen, the ionophore at different concentrations and in combination with TPA (IC₅₀ of 20M). Although not conclusive, the results are consistent with an inhibition of protein kinase C by phloretin at concentrations below 10 M. At higher concentrations unspecific actions become apparent and phloretin therefore seems to be of limited utility as a probe for signal-pathways in cell responses.     

Effects of inhibitors and ion substitutions on oscillations of cell membrane potential in cells expressing the RAS oncogene

Previous studies revealed that in NIH fibroblasts expressing the ras oncogene but not in other NIH fibroblasts, bradykinin leads to sustained, calcium dependent oscillations of cell membrane potential by repetitive activation of calcium-sensitive K⁺ channels. The present study has been performed to test for ion and inhibitor sensitivity of these oscillations. Both, Lys-bradykinin (kallidin) and bradykinin, but not any shorter peptide tested, maintained the oscillations. The oscillations are abolished in the presence of the K⁺ channel blocker barium (10 nmol/l). The amplitude but not the frequency of the oscillations is dependent on the extracellular potassium concentration. The oscillations are not dependent on the presence of extracellular sodium, bicarbonate or chloride. The oscillations are abolished in the absence of extracellular calcium and their frequency is significantly decreased at reduced extracellular calcium (to 0.2 mmol/l). The oscillations are not inhibited by acute administration of ouabain (0.1 mmol/l), by dimethylamiloride (100 mol/l), furosemide (1 mmol/l) and hydrochlorothiazide (100 mol/l), by cobalt (100 mol/l), zinc (100 mol/l), gadolinium (100 mol/l), verapamil (10 mol/l) and diltiazem (10 mol/l), but are abolished in the presence of 100 mol/l lanthanum, 1 mmol/l cadmium, 10 mol/l nifedipine, 25 mol/l SK & F 96365 and 200 mol/l TMB-8. Stimulation of calcium entry by 10 mol/l ionomycin is frequently followed by oscillations of cell membrane potential even in the absence of bradykinin. In conclusion, in cells expressing the ras oncogene bradykinin leads to sustained activation of calcium channels at the cell membrane, which cause oscillations of the cell membrane potential by triggering intracellular calcium release.     

On the regulation of the expressed L-type calcium channel by cAMP-dependent phosphorylation

The Ca²⁺ channel subunits _1C-a and _1C-b were stably expressed in Chinese hamster ovary (CHO) and human embryonic kidney (HEK) 293 cells. The peak Ba²⁺ current (I _Ba) of these cells was not affected significantly by internal dialysis with 0.1 mM cAMP-dependent protein kinase inhibitor peptide (mPKI), 25 M cAMP-dependent protein kinase catalytic subunit (PKA), or a combination of 25 M PKA and 1 M okadaic acid. The activity of the _1C-b channel subunit expressed stably in HEK 293 cells was depressed by 1 M H 89 and was not increased by superfusion with 5 M forskolin plus 20 M isobutylmethylxanthine (IBMX). The _1C-a·₂·₂/ complex was transiently expressed in HEK 293 cells; it was inhibited by internal dialysis of the cells with 1 M H 89, but was not affected by internal dialysis with mPKI, PKA or microcystin. Internal dialysis of cells expressing the _1C-a·₂·₂/ channel with 10 M PKA did not induce facilitation after a 150-ms prepulse to +50 mV. The Ca²⁺ current (I _Ca) of cardiac myocytes increased threefold during internal dialysis with 5 M PKA or 25 M microcystin and during external superfusion with 0.1 M isoproterenol or 5 M forskolin plus 50 M IBMX. These results indicate that the L-type Ca²⁺ channel expressed is not modulated by cAMP-dependent phosphorylation to the same extent as in native cardiac myocytes.     

Light and electron microscopic studies onMyxobolus cotti El-Matbouli and Hoffmann, 1987 infecting the central nervous system of the bullhead (Cottus gobio)

Myxobolus cotti (Myxozoa: Myxosporea) is described as found in the central nervous system of the bullhead (Cottus gobio) caught in the Alpine lake Königssee and in a brook in the Bavarian Forest, Federal Republic of Germany (El-Matbouli and Hoffmann 1987). Aggregations of spores and polysporoblastic trophozoites compressed and replaced large areas of the white and grey matter of the brain and spinal cord. These aggregations may be surrounded by a thin, connective tissue capsule; in a few cases they were associated with loose infiltrates of glial cells. Neither conspicuous tissue reactions nor inflammatory responses were evident. No other organs were seen to be infected withM. cotti. Mature spores are oval, with a tapering anterior end, and the pyriform polar capsules are nearly equal in size. Fresh spores measured 8.9–15.1 m in length (mean, 12.4 m) and 8–12.4 m in width (mean, 9.6 m); polar capsules were 4.3–9 m long (mean, 6.4 m); and 2–3.8 m wide (mean, 2.9 m). Light microscopy, the ultrastructure of pansporoblasts, sporogenesis and mature spores are described.     

Relation between cell na extrusion and transtubular absorption in the perfused toad kidney: the effect of K,ouabain and ethacrynic acid

Summary Transtubular absorption of Na and Cl, and intracellular ion concentrations were evaluated in toad kidneys perfused with solutions containing K and without K, and in the presence of 1 mM Ouabain and 1 mM Ethacrynic acid. The following values were obtained with 8.5 mM K: Transtubular absorption of Na and Cl68% (percent of filtered load); cell content 294 mole Na, 433 mole K, 100 mole Cl/g solids. Lack of K in the perfusate diminished transtubular absorption to 25% and the cells gain 244 mole Na/g solids, and lose an equimolecular quantity of K. The process is reversible upon raising the K concentration in the perfusate. Ouabain inhibits transtubular absorption to 6%; the cells lose about 110 mole K/g solids, but cellular Na is maintained at the control levels. Ethacrynic acid inhibits transtubular absorption to 3%; the cells approximately double their Na and Cl content, but their K is maintained at the control levels. These observations cannot be explained exclusively in terms of an effect on the distal tubule. Probably proximal as well as distal tubules are involved. A single Na pump seems insufficient to account for all experimental findings. The existence of two separate pumps is therefore proposed.     

Effect of epidermal growth factor on non-steroidal anti-inflammatory drug-induced intestinal damage

Epidermal growth factor (EGF, 10 g/kg po, ip, or sc, BID, and 20 g/kg iv) had no protective activity in the indomethacin-induced intestinal lesion model (6 h model). In the ethanol-induced gastric lesion model, EGF (10 g/kg sc) reduced lesions by 52% and reduced gastric acid secretion by 68% (5 g/kg iv). In the 24 h indomethacin-induced intestinal lesion model, pretreatment with EGF (10 g/kg sc, BID; 1 day before and during indomethacin treatment) had no beneficial effects. Therefore, EGF had no protective effects against non-steroidal antiinflammatory drug (NSAID)-induced intestinal lesions at doses that protect against the necrotizing action of ethanol and that inhibit gastric acid secretion in the rat.     

Roles of inositol trisphosphate and protein kinase C in the spontaneous outward current modulated by calcium release in rabbit portal vein

We examined the effects of heparin, guanosine nucleotides, protein kinase C (PKC) modulators, such as phorbol 12,13-dibutylate (PDBu) and H-7 on Ca²⁺-dependent K⁺ currents in smooth muscle cells of the rabbit portal vein using the whole-cell patch-clamp technique, to explore the effects of PKC on the oscillatory outward current (I _oo). Neomycin (30 M), an inhibitor of phospholipase C, and intracellular applications of heparin (10 g/ml) and guanosine 5-O-(2-thiodiphosphate) (GDP[S]; 1 mM) partly but consistently inhibited the generation of I _oo, whereas a higher concentration of heparin (100 g/ml) transiently enhanced then suppressed the generation of I _oo. Inhibition of I _oo generation by heparin was more powerful at the holding potential of + 20 mV than at –20 mV. Inositol 1,4,5-trisphosphate (InsP ₃; 30 M) continuously generated I _oo at holding potentials more positive than –60 mV. Noradrenaline (10 M) and caffeine (3–20 mM) transiently augmented, then reduced the generation of I _oo. Heparin (10 g/ml) completely inhibited responses induced by InsP ₃ and noradrenaline, but not those induced by caffeine. Intracellular application of guanosine 5-triphosphate (GTP; 200 M) or low concentrations of guanosine 5-O-(3-thiotriphosphate) (GTP[S]; 3 M) continuously augmented the generation of I _oo. High concentrations of GTP[S] (10 M) transiently augmented, then inhibited I _oo. Neither GTP[S] nor noradrenaline induced the transient augmentation or the subsequent inhibition of I _oo when applied in the presence of GDP[S] (1 mM), neomycin (30 M) or heparin (10 g/ml). PDBu (0.1 M) reduced the generation of I _oo but failed to produce an outward current following application of caffeine (3–5 mM). This action of PDBu was inhibited by pretreatment with H-7 (20 M). In the presence of H-7, GTP[S] continuously enhanced the generation of I _oo. The suppression of the generation of I _oo during application of noradrenaline (10 M) was reduced by pretreatment with H-7. Thus both InsP₃ and protein kinase C contribute to the generation of I _oo in smooth muscle cells of the rabbit portal vein and heparin is not a specific InsP ₃ antagonist on the InsP ₃-induced Ca²⁺-release channel (PIRC). InsP ₃ opens PIRC and protein kinase C may deplete the stored Ca²⁺ by either inhibiting the reuptake of Ca²⁺ or by enhancement of the releasing actions of InsP ₃.     

Efficient selection of μ m − mutants from μm-expressing myeloma cells by treatment with ricin A-conjugated anti-μ antibody

We have developed an efficient system for obtaining myeloma mutants defective intrans-acting factors required for immunoglobulin (Ig) gene expression. The system consists of a myeloma cell line designed for this purpose and an efficient method for selecting mutants from it. The cell line is X63.653 transfected with the gene, whose tailpiece sequence was replaced with the transmembrane sequence of human EGF receptor to hold on the cell surface and whose CH1 sequence was removed to prevent from being retained in the endoplasmic reticulum. It efficiently and stably expressed chains of IgM on the cell surface ( _m ⁺ ) without light chains. To obtain mutants lacking _m ( _m ^– ) from the _m ⁺ cell line by selectively killing _m ⁺ cells, a method with ricin A-conjugated anti- antibody was more reliable than complement lysis mediated by anti- antibody. Applying the system, we obtained a variety of _m ^– mutants.     

Über den Bau des Pferdeinfluenzavirus

Zusammenfassung Das Pferdeinfluenzavirus — Myxovirus influenzae A equi 2 (Miami 63) —, angereichert aus infizierten Kälbernieren-Zellkulturen und aus Allantoisflüssigkeit infizierter Hühnerembryonen, wurde elektronenoptisch untersucht. Es unterschied sich nicht von den bisher dargestellten Influenza-A-Viren von Mensch und Tieren.Die Viruspartikel von runder bis ovaler Form hatten Durchmesser von 70 bis 130 m. Daneben wurden auch filamentöse Partikel und polymorphe Riesenformen bis zu 700 m beobachtet. Die äußere Hülle der Pferdeinfluenzaviren bildet eine 6 bis 7 m starke Doppelmembran, in welcher die hohlen, zylindrischen Oberflächenprojektionen (Spikes) von 3×10 m Größe verankert sind. Bei intakten Partikeln von Influenzaviren dürften die Oberflächenprojektionen nach einem pentagonalen oder hexagonalen Muster angeordnet sein. An zerfallenen Partikeln und bei Anhäufungen freier Spikes ordneten sich letztere jedoch auch nach quadratischem Prinzip. Der Nukleoproteinstrang des Influenzakapsids hatte im intakten Partikel einen Durchmesser von 6 m, während aus dem Partikel ausgetretene Stränge 10 m. maßen.Ausgehend von diesen Differenzen des Strangdurchmessers und den abzuleitenden Zustandsänderungen wird ein neues Modell über den Aufbau des Nukleoproteinstranges zur Diskussion gestellt.

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Summary Equine influenza virus — Myxovirus influenzae A equi 2 (Miami 63) — grown in cultures of calf kidney cells or in the egg was concentrated and examined with the electron microscope. The virus did not differ from influenza A virus of human or animal origin already described in the literature.The virus particles were round to oval in shape with a diameter of 70 to 130 m. Filamentous and giant forms were also observed with dimensions up to 700 m. The outer envelope of equine influenza virus is a double membrane 6 to 7 m. thick, in which the hollow cylindrical spikes are anchored. The dimensions of the latters are 3×10 m. On intact influenza virus particles, spikes are grouped in pentagonal or hexagonal arrays. Free spikes as well as spikes on disintegrating virus particles show a tendency to quadratic arrays. The nucleoprotein strand in the intact virus was 6 m, thick whereas strands in a free state were 10 m. thick. On the basis of this difference, a new model is proposed for the structure of the nucleoprotein strand.

     

Effects of PAF and PAF antagonists on the shape of venous endothelial cellsin vitro

Three platelet-activating factor (PAF) antagonists were tested for their ability to prevent or reduce PAF-induced shape changes of large vein endothelial cellsin vitro. BN52021 had a significant protective action at concentrations of 1 M and 0.1 M, but at 100 M had a damaging effect of its own. CV3988 (0.1 M and 1 M) and L652, 731 (20 M) did not reduce the responses to PAF, and at higher concentrations (CV3988 10 M and 100 M, L652, 731 100 M) both compounds alone caused significant changes of shape. BN52021 (0.1 M) was also effective against leukotriene (LT) C₄, at 1 M against bradykinin and LTE₄, and at 10 M against LTD₄ and the calcium ionophore A23187. BN52021 (10 M) was ineffective against shape changes induced by histamine, prostaglandin (PG) E₂ and lysophosphatidylcholine (LPC). Neither indomethacin (100 M) nor verapamil (20 M) altered the response to PAF.Using electron spin resonance (ESR) spectrometry it was shown that the damaging effects of LPC and CV3988 may be due partly to their detergent properties. It is suggested that the mechanism by which PAF alters the shape of large vein endothelial cells is primarily receptor mediated.     

Neural nicotinic acetylcholine responses in solitary mammalian retinal ganglion cells

Using the patch-clamp technique,whole-cell recordings from solitary rat retinal ganglion cells in culture have established the nicotinic nature of the acetylcholine responses in these central neurons. Currents produced by acetylcholine (5–20 mol/l) or nicotine (5–20 mol/l) reversed in polarity near –5 mV and were unaffected by atropine (10 mol/l). Agonist-induced currents were blocked by low doses(2–10 mol/l) of the classical ganglionic antagonists hexamethonium and mecamylamine, as well as by d-tubocurarine and dihydro--erythroidine (the latter two do not discriminate clearly between ganglionic and neuromuscular junction receptors). Treatment with the potent neuromuscular blocking agent -bungarotoxin (10 mol/l) did not affect the cholinergic responses of these cells, while toxin F (0.2 mol/l), a neural nicotinic receptor antagonist, readily abolished acetylcholine-induced currents. Thus, the experiments performed to date show that the nicotinic responses of retinal ganglion cells in the central nervous system share the pharmacology of autonomic ganglion cells in the peripheral nervous system. The ionic current carried by the nicotinic channels was selective for cations, similar to that described for nicotinic channels in other tissues. In addition, single-channel currents elicited by acetylcholine were observed in whole-cell recordings with seals > 5 G as well as in occasional outside-out patches of membrane. These acetylcholine-activated events, which had a unitary conductance of 48 pS and a reversal potential of 0 mV, represent the ion channels that mediate the neural nicotinic responses observed in these experiments on retinal ganglion cells.     

Diameter and flow velocity changes of feline small pulmonary vessels in response to sympathetic nerve stimulation

Using an X-ray television system, we measured directly changes in the internal diameter (ID), flow velocity, and volume flow of the small pulmonary vessels (100–500 m ID) in response to electrical sympathetic nerve stimulation (SNS) in anaesthetized cats before and after adrenergic receptor blockade. Flow velocity was obtained by measuring the distance that the leading edge of the contrast medium moved per 0.1 s in the small arteries. Volume flow was obtained from the product of flow velocity and cross-sectional area calculated from the ID of the small arteries. SNS was accolmplished with 10- to 15-V square-wave pulses of 2-ms duration at 20–30 Hz for 20-s periods. In response to SNS, arterial ID decreased significantly by 8–13% in the 200- to 500-m vessels but not in the 100- to 200-m vessels. In the veins, on the other hand, there was no significant ID decrease in any of the 100- to 500-m vessels. After -receptor blockade (phentolamine, 2 mg/kg i.V.), there were significant ID increases (4–9%) in the 100- to 500-m arteries in response to SNS, the maximum increases being in the 100- to 200-m arteries. After -blockade (propranolol, 2 mg/kg i.V.), the ID decrease due to SNS in the 200- to 500-m arteries was enhanced (24–27%) and, in addition, the 100- to 200-m arteries exhibited a significant ID decrease (18%). Combined and -blockade completely abolished the ID decrease due to SNS. In the veins, on the other hand, no ID change occurred even after - or -blockade. The results indicate that SNS selectively constricts 200- to 500-m arteries. The data suggests that SNS has -mediated vasoconstrictor and -mediated vasodilator effects on the 100- to 500-m arteries and that the ID response pattern to SNS depends chiefly on the balance between -mediated vasoconstriction and -mediated vasodilation. Associated with the ID decrease due to SNS, flow velocity was increased by 21%. However, SNS did not affect volume flow, because the increase in velocity was compensated by the reduction in the cross-sectional area (due to the decreased ID).     

Ultrastructure and quantitative synaptology of the sacral parasympathetic nucleus

Summary This study examines the anatomical substrate for the spinal micturition reflex. Light microscopy of pyridine silver-stained sections revealed that the sacral parasympathetic nucleus (SPN) exists as a broken column or chain of cell clusters located along the intermediolateral portion of the dorsal horn in sacral segments S₂–S₄. Quantitative analysis of neuropil components in electron micrographs provides data for each type of bouton identified in this nucleus. On the somata of these neurons, boutons containing clear spherical vesicles (S type) comprise 70% of the bouton population. Terminals containing three or more dense core vesicles (GS boutons) account for 26% and boutons containing flattened vesicles (F boutons) comprise 4% of the population. F boutons are more common on large dendrites where they comprise 10% of the total bouton population.The actual population density of each bouton type is most evident when the number of boutons is expressed as boutons per 100 m of membrane length (btn/100 m). S type boutons are the most frequently encountered type. The population density of S boutons is the same on soma and dendrites at 6.66 btn/100 m. F boutons are more numerous on large (> 2 m) dendrites (1.28 btn/100 m) than on small dendrites (0.63 btn/100 m) or on somata (0.36 btn/ 100 m). GS boutons occur more frequently on small dendrites (3.66 btn/100 m) than on somata (2.29 btn/100 m), large dendrites (2.88 btn/100 m) or medium dendrites (2.27 btn/ 100 m). These data suggest that the dense core vesicle-containing boutons are applied primarily to small (<1 m) dendrites and that F boutons are associated mostly with large or proximal dendrites.These results provide a quantitative profile of the synaptic input to the sacral autonomic (parasympathetic) neurons which innervate the urinary bladder and demonstrate specific population differences on various postsynaptic structures in this nucleus.     

Enhanced stability of YEp plasmids in lager brewing yeasts is related to lager brewing yeast 2-μm DNA

Summary YEp plasmid stability in the presence of either Saccharomyces cerevisiae laboratory strain 2-m DNA, or lager brewing yeast 2-m DNA in the same genetic background, was compared under non-selective culture conditions. It was found that YEp plasmids were more stably maintained in the presence of lager 2-m DNA under these conditions. By construction of laboratory-lager 2-m DNA hybrid plasmids, an 867 bp StuI fragment of lager 2-m DNA was shown to be responsible for the enhanced stability of the YEp plasmid. Nucleotide substitutions at two sites were found by sequencing this region. It was also confirmed that increasing cell ploidy enhanced YEp stability under non-selective conditions.