Die vorderextremitat von opisthocomus cristatus (vieillot)

Ohne Zusammenfassung

Zeichenerklärung der Abbildungen

Abb. 1-6 Skelett an.v. Angulus dorsalis - ap.tb.med. Apex tuberculi medialis - b.p. Knochenplatte der Phal.l dig. 2 - c.l. Crus laterale tuberculi medialis - c.m. Crus mediale tuberculi medialis - col.tr. Collum troehleae - ep.a. Caput articulare - cr.lat. Crista lateralis - cr.med. Crista medialis - dig.d. Digitus 3 (Medius) - dig.4. Fraglicher Rest eines vierten Fingers, mit dem dritten verwachsen - ep.l. Epicondylus lateralis - ep.m. Epicondylus medialis - fiss. Fissura metacarpi - foss. Fossa pneumo-anconaea - fov. Fovea supratrochlearis ventralis - inc.coll. Incissura collaris - i.c. Impressio coraeo-brachialis ant - i.p. Impressio pectoralis - k. Knochenöse an der Phal. 2 dig. 2 - l.a.h. Linea anconaei humeralis dorsalis - l.d.v. Linea deltoidis ventralis - l.l.d. Linea latissimus dorsi anterioris - o. Olecranon - pl. Planum ulnare ventrale - p.ms. Processus muscularis metacarpi II - p.spc.l. Processus supracondyloideus later - r.m. Radialhöcker des Metacarpus I - s. Sesambein - s.anc.l. Sulcus anconaeus lateralis - s.anc.m. Sulcus anconaeus medialis - s.d.c. Sulcus tendinis Musculi extensoris digitorum communis - s.r. Sulcus extensoris metacarpi radialis - tbdat. Tuberculum lateralis - tb.med. Tuberculum medialis - tb.ms. Tuberculum muscularis zur Insertion des Musculus extensor metacarpi uln - tb.r. Tuberculum radialis - tb.u. Tuberculum ulnaris - tr.r. Trochlea radialis - tr.u. Trochlea ulnaris - v.itr. Vallis intertrochlearis Abb. 8-10 Nerven a.h. Nervus anconaeus humeralis - a.sc. Nervus anconaeus scapularis - ab.ind. Nervus abductor indicis - ab.p. Nervus abdoctor pollicis - ad.p. Nervus adductor pollicis - b. Nervus biceps - br.inf. Nervus brachialis inferior - cbr.a. Nervus coraco-brachialis anterior - cbr.p. Nervus coracobrachialis posterior - cut.b Nervus cutaneus brachii - d.min. Nervus deltoides minor - d.mj. Nervus deltoides major - d.ppt. Nervus deltoides propatagialis - ect.r. Nervus ectepicondylo-radialis - ect.u. Nervus ectepicondylo-ulnaris - e.c.u. Nervus extensor carpi ulnaris - e.d.c. Nervus extensor digitorum communis - e.i.b. Nervus extensor indicis brevis - e.i.l. Nervus extensor indicis longus - e.m.r. Nervus extensor metacarpi radialis - ent.r.s. Nervus entepicondylo-radialis sublimis - Int.r.p Nervus entepicondylo-radialis profund - e.p.b. Nervus extensor pollicis brevis - e.p.l. Nervus extensor pollicis longus - f.c.u. Nervus flexor carpi ulnaris - f.d.III. Nervus flexor digiti III - f.d.p. Nervus flexor digitorum profundus - f.d.s. Nervus flexor digitorum sublimis - f.p. Nervus flexor pollicis - i.d. Nervus interosseus dorsalis - i.p. Nervus interosseus palmaris - lat.d. Nervus latissimus dorsi - m. Nervus metapatagialis - p. Nervus pectoralis - prop.i. Nervus propatagialis inferior - prop.s. Nervus propatagialis superior - sbc.l. Nervus subscapularis internum et coracoideum - sbc.2. Nervus subscapularis externum - sch. Nervus seapulo-humeralis - spc. Nervus supracoracoideus - u.m.d. Nervus ulni-metacarpalis dorsalis - u.m.v. Nervus ulni-metacarpalis ventralis Abb. 11-32 Muskeln Abkürzungen: a. Musculus anconaeus - ab.ind. Musculus abductor indicis - ab.p. Musculus abductor pollicis - ad.p. Musculus adductor pollicis - a.h. Musculus anconaeus humeralis - a.sc. Musculus anconaeus scapularis - b. Musculus biceps brachii - b.ppt. Musculus biceps propatagialis - br.inf. Musculus brachialis inferior - cbr.a. Musculus coraco-brachialis anterior - cbr.p. Musculus coraco-brachialis posterior - d.min. Musculus deltoides minor - d.mj. Musculus deltoides major - d.ppt. Musculus deltoides propatagialis - ect.r. Musculus ectepicondylo-radialis - ect.u. Musculus ectepicondylo-ulnaris - e.c.u. Musculus extensor carpi ulnaris - e.d.c. Musculus extensor digitorum communis - e.i.b. Musculus extensor indicis brevis - e.i.l. Musculus extensor indicis longus - El. Elastica - E.S. Expansor secundariorum - e.m.r.b. Musculus extensor metacarpi radialis brevis - e.m.r.l. Musculus extensor metacarpi radialis longus - ent.r.s. Musculus entepicondylo-radialis sublimis - ent.r.p. Musculus entepicondylo-radialis profundus - e.p.b. Musculus extensor pollicis brevis - e.p.l. Musculus extensor pollicis longus - f.c.u. Musculus flexor carpi ulnaris - f.d.III. Musculus flexor digiti III - f.d.p. Musculus flexor digitorum profundus - f.d.s. Musculus flexor digitorum sublimis - f.p. Musculus flexor pollicis - i.d. Musculus interosseus dorsalis - i.p. Musculus interosseus palmaris - lat.d.a. Musculus latissimus dorsi anterior - lat.d.p. Musculus latissimus dorsi posterior - L.ch. Ligamentum coraco-humerale - p. Musculus pectoralis thoracicus - p.ppt. Musculus pectoralis propatagialis - Prop. b. Propatagialis brevis - Prop.l. Propatagialis longus - sbc.c. Musculus subcoraco-scapularis coracoideum - sbc.e. Musculus subcoraco-scapularis externum - sbc.i. Musculus subcoraco-scapularis internum - sch. Musculus scapulo-humeralis (posterior) - spc. Musculus supra coracoideus - s.s.a. Musculus serratus superficialis anterior - T.m. Tendo matapatagialis - u.m.d. Musculus ulni-metacarpalis dorsalis - u.m.v. Musculus ulni-metacarpalis ventralis     

Current-voltage relationships of potassium channels in the plasmalemma ofAcetabularia

Summary The outer membrane of mechanically prepared protoplasmic droplets fromAcetabularia mediterranea has been investigated by patch-clamp techniques. These membranes are shown to consist of physiologically intact plasmalemma. With the Cl^– pump inhibited, microscopic currents through K⁺-selective channels were studied. These currents compare well with macroscopic K⁺ currents as previously determined by standard microelectrode techniques and tracer flux measurements. There is about one K⁺ channel per m² in the plasmalemma. The current-voltage relationship (I–V curve) of the main open channel (channel A) is sigmoid over a voltage range between about –100 and +100 mV with saturation currents of about ±10 pA. A second species (or different state of channel A) of K⁺-selective channels (channel B) differs from channel A by smaller saturation currents (about ±7 pA) and a much smaller open probability. The open probability of channel A increases from almost zero at large negative voltages to about 1/2 at large positive voltages. Taking the closed times into account, the mean steady-stateI–V curve of channel A displays outward rectification about the equilibrium voltage for K⁺ and negative slope conductance at larger negative voltages. The open channelI–V curve of the open channels A and B, the changes of theI–V curve of the open channel A upon variation of the external K⁺ concentration, as well as the mean steady-stateI–V curves of channel A are described by simple reaction kinetic models, the parameters of which are determined to fit the experimental data. The results are discussed with respect to data from other K⁺ channels in plants and with respect to regulation of the cytoplasmic K⁺ concentration inAcetabularia.     

Potassium-proton symport inNeurospora: kinetic control by pH and membrane potential

Summary Active transport of potassium in K⁺-starvedNeurospora was previously shown to resemble closely potassium uptake in yeast,Chlorella, and higher plants, for which K⁺ pumps or K⁺/H⁺-ATPases had been proposed. ForNeurospora, however, potassium-proton cotransport was demonstrated to operate, with a coupling ratio of 1 H⁺ to 1 K⁺ taken inward so that K⁺, but not H⁺, moves against its electrochemical gradient (Rodriguez-Navarro et al.,J. Gen. Physiol. 87:649–674).In the present experiments, the current-voltage (I–V) characteristic of K⁺–H⁺ cotransport in spherical cells ofNeurospora has been studied with a voltage-clamp technique, using difference-current methods to dissect it from other ion-transport processes in theNeurospora plasma membrane. Addition of 5-200 M K⁺ to the bathing medium causes 10–150 mV depolarization of the unclamped membrane, and yields a sigmoidI–V curve with a steep slope (maximal conductance of 10–30 S/cm²) for voltages of –300 to –100 mV, i.e., in the normal physiologic range. Outside that range the apparentI–V curve of the K⁺-H⁺ symport saturates for both hyperpolarization and depolarization. It fails to cross the voltage axis at its predicted reversal potential, however, an effect which can be attributed to failure of theI–V difference method under reversing conditions.In the absence of voltage clamping, inhibitors—such as cyanide or vanadate—which block the primary proton pump inNeurospora also promptly inhibit K⁺ transport and K⁺-H⁺ currents. But when voltage clamping is used to offset the depolarizing effects of pump blockade, the inhibitors have no immediate effect on K⁺-H⁺ currents. Thus, the inhibition of K⁺ transport usually observed with these agents reflects the kinetic effect of membrane depolarization rather than any direct chemical action on the cotransport system itself.Detailed study of the effects of [K⁺]_o and pH_o on theI–V curve for K⁺-H⁺ symport has revealed that increasing membrane potential systematicallydecreases the apparent affinity of the transporter for K⁺, butincreases affinity for protons (K _m range: for [K⁺]_o, 15–45 M; for [H⁺]_o, 10–35 nM). This behavior is consistent with two distinct reaction-kinetic models, in which (i) a neutral carrier binds K⁺ first and H⁺ last in the forward direction of transport, or (ii) a negatively charged carrier (–2) binds H⁺ first and K⁺ last.     

Interactions of cardiac glycosides with cells and membranes Properties and structural aspects of two receptor sites for ouabain in erythrocytes

The existence of two types of binding sites for ouabain in human erythrocyte membranes is described. Receptor sites designated as ‘type I’, which may be identical to the K⁺-insensitive sites of intact cells, were detected at concentrations of ouabain as low as 10⁻⁷ M. The ‘type II’ receptor sites require the inclusion of Mg²⁺ + P_i to form complexes with ouabain; they may be identical to the K⁺-sensitive sites of intact cells. These sites were saturated at approx. 5 · 10⁻⁷ M ouabain but could not be detected at higher concentrations. The range of ouabain concentrations at which ‘type I’ receptors start to predominate (i.e. 5 · 10⁻⁸–5 · 10⁻⁷ M) was termed ‘critical digitalis concentrations’. The process of binding reached equilibrium within 1 and 4 h for ‘type I’ and ‘type II’ sites, respectively. The dissociation constant for ‘type II’ receptor-ouabain complexes was 7.6 · 10⁻⁹ M.Under similar experimental conditions, rat erythrocyte membranes exhibited only non-saturable sites.Alterations in the proportions of the two types of receptors were demonstrated by preincubation of the membranes, in the presence or absence of Mg²⁺ + P_i, prior to the addition of ouabain. In the first case, ‘type II receptor-ouabain’ complexes were stabilized at about 50% of the untreated membranes and ‘type I-ouabain’ complexes slowly approached equilibrium over a period of 24 h. In the latter instance, ‘type I’ receptors were not detected, and only ‘type II-ouabain’ complexes prevailed.     

Voltage dependence of Na/K pump current inXenopus oocytes

Summary Stage V and VI (Dumont, J.N., 1972.J. Morphol. 136:153–180) oocytes ofXenopus laevis were treated with collagenase to remove follicular cells and were placed in K-free solution for 2 to 4 days to elevate internal [Na]. Na/K pump activity was studied by restoring the eggs to normal 3mm K Barth's solution and measuring membrane current-voltage (I–V) relationships before and after the addition of 10 m dihydroouabain (DHO) using a two-microelectrode voltage clamp. Two pulse protocols were used to measure membraneI–V relationships, both allowing membrane currents to be determined twice at each of a series of membrane potentials: (i) a down-up-down sequence of 5 mV, 1-sec stair steps and (ii) a similar sequence of 1-sec voltage pulses but with consecutive pulses separated by 4-sec recovery periods at the holding potential (–40 mV). The resulting membraneI–V relationships determined both before and during exposure to DHO showed significant hysteresis between the first and second current measurements at each voltage. DHO difference curves also usually showed hysteresis indicating that DHO caused a change in a component of current that varied with time. Since, by definition, the steady-state Na/K pumpI–V relationship must be free of hysteresis, the presence of hysteresis in DHO differenceI–V curves can be used as a criterion for excluding such data from consideration as a valid measure of the Na/K pumpI–V relationship. DHO differenceI–V relationships that did not show hysteresis were sigmoid functions of membrane potential when measured in normal (90mm) external Na solution. The Na/K pump current magnitude saturated near 0 mV at a value of 1.0–1.5 A cm^–2, without evidence of negative slope conductance for potentials up to +55 mV. The Na/K pump current magnitude in Na-free external solution was approximately voltage independent. Since these forward-going Na/K pumpI–V relationships do not show a region of negative slope over the voltage range –110 to +55 mV, it is not necessary to postulate the existence of more than one voltage-dependent step in the reaction cycle of the forward-going Na/K pump.     

Physiologisch-anatomische Studien am Fu? der Spechte

Zusammenfassung 1. Zur Regulierung der Bewegungen der rückwärts gerichteten vierten Zehe ist bei den Spechten am distalen Teil des Laufes ein Wendehöcker vorhanden; er wirkt als Rolle und ändert die Zugrichtung der Sehne desMusc. flexor sublimis.2. Aehnliche Vorrichtungen bestehen auch am Lauf anderer Vögel mit rückwärts gerichteter vierter Zehe oder Wendezehe. Eine vergleichende Betrachtung lehrt, daß die Wendehöcker hervorgegangen sind aus der ursprünglichen für die vierte Zehe bestimmten Gelenkrolle, die eine Differenzierung in Wendehöcker und spezielle Gelenkfläche erfahren hat.3. Das Metatarsale I dient als Wendehöcker für die rückwärts gerichtete erste Zehe. Vermutlich ist diese Funktion die Ursache dafür, daß dieser Knochen im Lauf der Phylogenese nicht wie die Metatarsalia II–IV in die Bildung des Laufknochen aufgegangen, sondern selbständig geblieben ist.4. Es wird eine Analyse aller Bewegungen der vierten Zehe gegeben und festgestellt, daß die beim Klettern angewendeten Abspreizbewegungen nur modifizierte Umklammerungsbewegungen sind.5. Es werden zwei Sperrvorrichtungen beschrieben, welche bewirken, daß die Insertion desMusc. flexor sublimis der zweiten und dritten Zehe statt an den Grundphalangen am distalen Laufende erfolgt. Diese Konstruktionen werden als Hilfseinrichtungen für das Klettern gedeutet, deren Aufgabe darin besteht, das Heranziehen oder Abschleudern des schweren Rumpfes zu erleichtern und den Muskelzug federnd abzufangen.     

Mortality rates of Lates niloticus,L. in Lake Nasser

Landings of Lates niloticus from Lake Nasser belonged to age groups I–VII, with II–III predominent. Mortality rate, as computed by two different methods, ranges around 75%. Turbid flood water did not reach Lake Nasser in 1972, and this fact may be responsible for the decline in the commercial catch from 1972 to 1973.     

Electrical characteristics of stomatal guard cells: The contribution of ATP-dependent, “Electrogenic” transport revealed by current-voltage and difference-current-voltage analysis

Summary The steady-state, current-voltage (I–V) characteristics of stomatal guard cells fromVicia faba L. were explored by voltage clamp using conventional electrophysiological techniques, but with double-barrelled microelectrodes containing 50mm K⁺-acetate. Attention was focused, primarily, on guard cell response to metabolic blockade. Exposures to 0.3–1.0mm NaCN and 0.4mm salicylhydroxamic acid (SHAM) lead consistently to depolarizing (positive-going) shifts in guard cell potentials (V _m ), as large as +103 mV, which were generally complete within 60–90 sec (mean response half-time, 10.3±1.7 sec); values forV _m in NaCN plus SHAM were close or positive to –100 mV and well removed from the K⁺ equilibrium potential. Guard cell ATP content, which was followed in parallel experiments, showed a mean half-time for decay of 10.8±1.9 ([ATP] _t=0, 1.32±0.28mm; [ATP] _{t=60–180sec}, 0.29±0.40mm). In respiring cells, theI–V relations were commonly sigmoid aboutV _m or gently concave to the voltage axis positive toV _m . Inward- and outward-rectifying currents were also observed, especially near the voltage extremes (nominally –350 and +50 mV). Short-circuit currents (atV=0 mV) were typically about 200–500 mA m^–2. The principal effect of cyanide early on was to linearize theI–V characteristic while shifting it to the right along the voltage axis, to decrease the membrane conductance, and to reduce the short-circuit current by approx. 50–75%. The resulting difference-current-voltage (dI–V) curves (±cyanide) showed a marked sensitivity to voltages negative from –100 mV and, when clamp scans had been extended sufficiently, they revealed a distinct minimum near –300 mV before rising at still more negative potentials. The difference currents, along with changes in guard cell potential, conductance and ATP content are interpreted in context of a primary, ATP-consuming ion pump. FittingdI–V curves to reaction kinetic model for the pump [Hansen, U.-P., et al. (1981)J. Membrane Biol. 63:165; Blatt, M.R. (1986)J. Membrane Biol. 92:91] implicates a stoichiometry of one (+) charge transported outward for each ATP hydrolyzed, with pump currents as high as 200 mA m^–2 at the free-running potential. The analysis indicates that the pump can comprise more than half of the total membrane conductance and argues against modulations of pump activity alone, as an effective means to controlling K⁺ transport for stomatal movements.     

Contractile responses in rat extensor digitorum longus muscles at different times of postnatal development

Some contractile properties of small bundles (100–200 m diameter) of muscle fibres isolated from the extensor digitorum longus muscle of rats at different times of development were compared. An increase of resting potential was observed in these muscles from-26.9 mV at 1 day of age to-72.6 mV at 3 months. Twitch tension and duration of postnatal muscles 1–7 days were diminished by reducing [Ca]_o (substituted by Mg²⁺) or adding inorganic cations (Ni²⁺, Cd²⁺, La³⁺), unlike in the oldest animals (14 days–3 months postnatal) where twitch responses were unaffected. In the latter, potentiation of the twitch tension was even recorded in the presence of Ni²⁺ (0.5–1 mmol·l^-1) and Cd²⁺ (0.5–2 mmol·l^-1). Properties of activation and inactivation of the developed tension following elevation of [K]_o to 15–200 mmol·l^-1 were analysed at the same stages of postnatal development. In contrast to the tension-membrane potential curves for activation, which presented an average negative shift of-17.6 mV between 1 day postnatal and 3 months of age, a voltage dependence of inactivation similar to that encountered in adult extensor digitorum longus muscles, was already reached at 7 days of age. These results suggest an asynchronism in the maturation of the potential-dependent characteristics of the depolarization-contraction coupling mechanism. Furthermore, during the first week postnatal, in relation with poorly developed membrane systems and low [Ca]_i-recycling capability, [Ca]_o plays a fundamental role in maintaining contraction by replenishing the intracellular calcium pool.Abbreviations ATPase adenosine triphosphatase - [Ca]_o ([K]_o) extracellular calcium (potassium) concentration - DC depolarization-contraction - EC excitation-contraction - e.d.l. muscle extensor digitorum longus muscle - E _m membrane potential - E _r resting potential - HEPES N-2 hydroxyethylpiperazine-N-2 ethanesulphonic acid - I _fast fast calcium current - sr sarcoplasmic reticulum - T-tubules transverse tubules     

Current-voltage relationships and voltage sensitivity of the Cl− pump inHalicystis parvula

Summary The current-voltage (I–V) relationships for internally perfused and nonperfused cells ofHalicystis parvula were determined. In both types of cells theI–V curve shows a conspicuous region of negative slope, beginning at vacuole potentials around –30 mV and continuing to values of +20 to +40mV. The negative slope in perfused cells is abolished by the metabolic inhibitors, darkness and low temperature. In order to determine the origin of this negative slope, we measured the voltage sensitivity of the unidirectional fluxes of Cl^–, Na⁺ and K⁺ in perfused cells. The results show that the Cl^– influx, which is mediated primarily by a Cl^– pump, increases as the vacuole potential is clamped at increasingly morenegative values up to –50 mV, while the other fluxes measured changed in the directions predicted by the change in electrical driving force. The voltage sensitivity of the Cl^– pump quantitatively accounts for the negative slope of theI–V curve. Also, we observed a large transient outward current of 10–20-sec duration following an abrupt depolarization by voltage clamping. This transient current was reduced or abolished by low temperature, which suggests that it may be due to the voltage-sensitive Cl^– pump. Finally, we found an inverse relationship between the transprotoplasm resistance (R _m ) and thePD under standard conditions, which suggests that the activity of the electrogenic Cl^– pump lowerR _m , i.e., it is a conductive pump.     

Mechanisms of wing rotating regulation in Calliphora erythrocephala (Insecta,Diptera)

Summary The blowfly Calliphora erythrocephala rotates its wings, i.e. changes the geometrical angle of attack, generating forces and moments for flight steering. There are two possibile ways to regulate this angle. The mechanisms for these movements are described. (1) The leading edge and the anterior part of the wing — between the costal vein and radial vein 4 — are pronated automatically due to the interaction of the moving parts during the downstroke. They are supinated during the upstroke. This is basic automatic regulation. (2) The posterior part of the wing — behind the anterior cross vein — is pronated and supinated independently of wing-drive. This is wing-drive independent additional regulation.Abbreviations a.c anterior cross vein - a.n anal veins - a.t.l anterior tergal lever - a.w anterior part of the wing - b.z bending zone - co costal vein - cr crossing of the tendons of the posterior notal wing process - c.s cross section - cu cubital vein - f fit or turning point of ventral radial vein 1 - h.a horizontal axis of pterale III - h.c humeral cross vein - h.co head of costal vein - h.r head of radial vein - k Klöppel - l.a longitudinal axis - me median vein - mp middle plate - ms mesoscutum - p anterior process of the anal veins - p.c posterior cross vein - pl pleurum - p.n.w.p posterior notal wing process - p.n.w.p 1–4 muscles 1–4 of the posterior notal wing process - pt I–III pterale I–III - p.t.l posterior tergal lever - p.w. posterior part of the wing - p.w.j pleural wing joint - r 1–4 radial veins 1–4 - r.s. ring stiffenings - sc subcostal vein - s.p semicircular part of the middle plate - s.t subalar tendon - t.c tip cross vein - te tegula - t.st thin strips - t.v.r tooth of ventral radial vein - v.a. vertical axis of pterale III - w wing - III 1–4 muscles 1–4 of pterale III     

High-performance liquid chromatographic assay for the determination of the novel etoposide derivative dimethylaminoetoposide (NK611) and its metabolites in urine of cancer patients

A simple, reproducible and specific urine assay for the novel epipodophyllotoxin derivative dimethylaminoetoposide (NK611, I) its picro form (III), the N-demethyl metabolite (II) and its picro form (IV) is reported. The method involves the addition of Pr-NK611 as internal standard, chloroform extraction and HPLC separation on a Nova-Pak C₁₈ column with a mobile phase of acetonitrile-0.05 M KH₂PO₄ (pH 6.4) (23:77, v/v). UV detection was used with absorbance monitored at 205 nm and the limit of quantification was 100 ng/ml. The intra- and inter-day precisions were within the ranges 1.1–3.4% and 1.9–2.4% for all analytes and the accuracy was 101–107%. The extraction recovery was more than 88% for I, II and IV and more than 83% for III. The assay is applicable to the urinary monitoring of I–IV in clinical pharmacokinetic investigations.     

The relationship between nutrient feed rate and specific growth rate in fed batch cultures

Summary Equations are described which relate nutrient feed rate to specific microbial growth rate in fed batch culture. Fed batch cultures are classified into three types: 1) those allowing constant specific microbial growth rate, 2) those in which the rate of change of flow rate is constant and 3) those in which the nutrient flow rate is constant. The basic properties of these three types are described.Symbols F medium flow rate, L³ T^–1 - F _o medium flow rate at zero time, L³ T^–1 - g rate of change of flow rate with time, L³ T^–2 - K _v volume constant, being the total cell weight at zero time divided by the product of the yield coefficient and growth-limiting substrate concentration in the feed, L³ - s _r growth limiting substrate concentration in the feed, ML^–3 - V volume of liquid in the growth vessel, L³ - V _f volume of medium fed to the growth vessel, L³ - V _o volume of liquid in the growth vessel at zero time, L³ - X total weight of cells, M - x concentration of cells, ML^–3 - X _g total weight of cells grown, M - X _o total weight of cells at zero time, M - Y yield coefficient, weight of cells grown per unit weight of growth-limiting substrate - specific microbial growth rate, T^–1     

Thyroid hormone action on mitochondria

Measurements of fluorescence at >420 nm and extracted NADPH in mitochondria obtained from the livers of hypothyroid rats show that the addition of Pi, ADP and glutamate rapidly reduces over 90% of the total reducible intrinsic pyridine nucleotides in State 3, compared with 20% in normals. The total fluorescence intensity change and reducible NADP⁺ is about twice normal in hypothyroid mitochondria. Adding 6–30 µMl-thyroxine to hypothyroid mitochondriain vitro decreases and delays the substrate-induced reduction of pyridine nucleotides, and excludes both NADP⁺ from such reduction and NADPH from oxidation by added ADP + Pi, without changing the high NADP(H) content. The correcting actions of the hormone are rapidly reversed by albumin, probably by binding free hormone. Changes in respiration do not appear to account for these observations. There is indirect evidence for decreased phosphorylation of added ADP in hypothyroid mitochondria, and a correction by added hormone. The hormonal actions on NADP(H) redox reactions are not reproduced by 1 to 6 µM dinitrophenolin vitro.l-Thyroxine appears to specifically block the participation of NADP (H) in redox reactions in mitochondria from hypothyroid rats, perhaps by effecting a sequestration of the nucleotide, by inhibiting the pyridine nucleotide transhydrogenase, or by activating an energy-linked process that competes with transhydrogenation.Papers I–III in this series were published inArch. Biochem. Biophys.I–124 (1968) 238.II–124 (1968) 248.III–150 (1972) 618.This work was supported by grants from the NIH (AM13564) and from The John A. Hartford Foundation.     

Untersuchungen über die bewegungsphysiologie der fangorgane am kopf der chätognathen

Zusammenfassung Nach Erläuterung der Morphologie der im Dienste des Beutefanges stehenden Hartteile des Chätognathenkopfes und nach Behandlung der Schwimmbewegungen der Pfeilwürmer nebst Bemerkungen über Art und Wahrnehmung der Nahrungsobjekte wird die allgemeine Wirkungsweise der Kopfbewaffnung beim Nahrungserwerb klargelegt. Den Hauptteil der Untersuchung bildet die funktionell-morphologische Analyse der Bewegungsphänomene am Chätognathenkopf während des Beutefanges. Der Bewegungsablauf des Fangmechanismus wird in fünf Phasen eingeteilt. In den ersten beiden erfolgt das Zurückstreifen der Kopfkappe, die dritte Phase führt zur Fangbereitschaftsstellung, während der beiden letzten laufen die eigentlichen Fangbewegungen ab. Die Untersuchung der Bewegungsvorgänge am Kopf erfolgte fast durchweg an lebenden Tieren, die Darstellung der einzelnen Bewegungsstufen mit Hilfe der Mikrophotographie. Genau analysiert werden die Vorgänge der starken Umformung des Kopfes bei den Fangbewegungen unter Feststellung der beteiligten Muskeln und Skelettelemente des Kopfes, vor allem der Lateralspangen. Die weitgehenden Änderungen der Kopfgestalt in den letzten beiden Phasen erfolgen vorwiegend auf der Ventralseite des Kopfes; infolgedessen erfahren die dorsal gelegenen Organe (Gehirn+ Retrocerebralorgan, Augen und Corona ciliata) relativ geringfügige Verlagerungen, wodurch ihr Funktionieren auch während der komplizierten Fangbewegungen gewährleistet ist. Die jeweilige Lage der Skelettelemente des Kopfes in den einzelnen Bewegungsphasen läßt sich an fixiertem Material, zur Kontrolle und Erweiterung der Ergebnisse der Lebenduntersuchung, durch elektive Färbung mit Kongorot ermitteln.Erklärung der Abkürzungen au Auge - co Corona ciliata - ew epdw dorsaler Epidermiswulst - fc Frontalkonnektiv - gp Punktsubstanz des Oberschlund - h Halsmuskulatur: Musc. rectus colli internus und externus - hz Hinterzähne - jg unfertige Greifhaken - kk Kopfkappe (= Präputium) - krs Kopf-Rumpfseptum - l, ls Lateralspange - m Mundöffnung - mau Musc. adductor uncinorum - mb Musc. bicornis - mcl Musc. complexus lateralis - md Mitteldarm - mol Musc. obliquus capitis longus - mp Musc. protractor praeputii - mtd Musc. transversus dorsalis - p Präputium (= Kopfkappe) - pd dorsale A-förmige Anwachszone des Präputiums - r Rückenpfeiler des Greifhakens - rcm dorsale Mündung des Retrocerebralorgans - s Schneidenpfeiler der Greifhaken - sk Spitzenkurve der Greifhaken - tv Musc. transversus ventraals - v Vestibulum - vd Vorderdarm - veg Vestibulargruben - vew Vestibularwülste - vl ventrale Längsmuskeln - vs Ventralspange - vw Vestibularwülste - vz Vorderzähne     

A kinetic analysis of the electrogenic pump ofChara corallina: III. Pump activity during action potential

Summary The current-voltage curve (I–V curve) of theChara membrane was obtained by applying a slow ramp hyper- and depolarization by use of voltage clamp. By inhibiting the electrogenic pump with 50m DCCD (dicyclohexylcarbodiimide), theI–V curve approached a steadyI–V curve within two hours, which gave thei _d -V curve of the passive diffusion channel. Thei _p -V curve of the electrogenic pump channel was obtained by subtracting the latter from the former. The sigmoidali _p -V curve could be simulated satisfactorily with a simple reaction kinetic model which assumes a stoichiometric ratio of 2. The emf of the pump (E _p ) is given as the voltage at which the pump current changes its sign. The conductance of the pump (g _p ) can be calculated as the chord conductance from thei _p -V curve, which is highly voltage dependent having a peak at a definite voltage. The changes of emf and conductance during excitation were determined by use of the current clamp (I=0). Since theE _p andg _p (V) are known, the changes, during excitation, of emf (E _d ) and conductance (g _d ) of the passive diffusion channel can be calculated. The marked increase of the membrane conductance and the large depolarization during the action potential are caused by the marked increase of the conductance of the passive diffusion channel and the large depolarization of its emf. The conductance of the electrogenic pump decreases to about half at the peak of action potential, while the pump current increases almost to a saturated level.     

Integral kinetics of the cleavage of maltose catalysed by α-glucosidase fromSaccharomyces carlsbergensis

Summary A new, sensitive and continuous assay for -glucosidase is described exploiting the different angles of rotation for the substrate maltose and the product glucose. Kinetic experiments revealed a very pronounced product inhibition of -glucosidase fromSaccharomyces carlsbergensis with a K_i of 4.85·10^–3 M for glucose.The K_M of maltose was found to be 37.8·10^–3 M. Taking these values, an integral kinetic curve for the enzymatic hydrolysis of maltose was calculated, which is shown to fit the experimental data.Symbols used k₁ (min^–1) pseudo first-order rate constant (for enzymatic cleavage) - k₂ (min^–1) rate constant (for mutarotation reaction) - I, P (mol/1) inhibitor (product) concentration - k_i (mmol/1) inhibitor constant - K_M (mmol/l) Michaelis constant - [M] ₅₈₉ ³⁰ (degree/m · l/mol) molecular rotation at 30°C and 589 nm - s (mmol/l) substrate concentration - R (mmol/mg · min) reaction rate - V_max (mmol/mg · min) maximal rate - U (mol/min) activity unit (here at 30°C and pH=6.8) Indices O initial value - max maximal value     

Single chloride channels in colon mucosa and isolated colonic enterocytes of the rat

Summary Chloride channels from rat colonic enterocytes were studied using the patch-clamp technique. After removal of mucus, inside-out patches were excised from the apical membrane of intact epithelium located at the luminal surface. They contained spontaneously switching Cl^– channels with a conductance of 35–40 pS. The channels were blocked reversibly by anthracene-9-carboxylic acid (1mm).In excised patches from single enterocytes, isolated by calcium removal, the Cl^– channels were studied in more detail. TheI–V relation was linear between ±80 mV. The selectivity was I^–>Br^–>Cl^–=NO ₃ ^– >F^–=HCO ₃ ^– .Thirty pS Cl^– channels were also found on the basolateral membrane of crypts isolated by brief calcium removal. TheI–V curve of these Cl^– channels was also linear.The results provide direct evidence for the existence of Cl^– channels in the apical membrane of surface cells in colonic mucosa. The properties of these channels are similar to those previously observed when incorporating membrane vesicles into planar lipid bilayers. Both results support the validity of the theoretical models describing intestinal secretion.     

Wing and tail myology of Tyto furcata (Aves,Tytonidae)

Barn Owls (Tytonidae) are nocturnal raptors with the largest geographical distribution among Strigiformes. Several osteological, morphometrical, and biomechanical studies of this species were performed by previous authors. Nevertheless, the myology of forelimb and tail of the Barn Owls is virtually unknown. This study is the first detailed myological study performed on the wing and tail of the American Barn Owl (Tyto furcata). A total of 11 specimens were dissected and their morphology and muscle masses were described. Although T. furcata has the wing and tail myological pattern present in other species of Strigiformes, some peculiarities were observed including a difference in the attachment of m. pectoralis propatagialis due to the lack of the os prominence, and the presence of an osseous arch in the radius that seems to widen the anchorage area of the mm. pronator profundus, extensor longus alulae, and extensor longus digiti majoris. Furthermore, the m. biceps brachii has an unusual extra belly that flexes the forearm. The interosseous muscles have a small size and lacks ossified tendons. This feature may be indicative of a lower specialization in the elevation and flexion of the digiti majoris. Forelimb and tail muscle mass account for 10.66 and 0.24% of the total body mass, respectively. Forelimb muscle mass value is similar to the nocturnal (Strigiformes) and diurnal (Falconidae and Accipitridae) raptors, while the tail value is lower than in the diurnal raptors (Falconidae and Accipitridae). The myological differences with other birds of prey are here interpreted in association with their “parachuting” hunting style. This work complements our knowledge of the axial musculature of the American Barn owls, and provides important information for future studies related to functional morphology and ecomorphology.