Circulatory physiology ofNautilus

Summary Present information places the circulatory performance ofNautilus at the bottom of the cephalopod scale but shows it to be distinctly different from that of gastropods and bivalves. The feature which clearly places it closer to its coleoid relatives than to other groups of molluscs is the enhancement of the branchial circulation by the beating pericardial glands and renal appendages. These organs have their homologues in the coleoid pericardial chamber. Recently, studies of living embryos show that the development of a functional circulatory system is an early event during ontogeny and that this information may have important implications for our understanding of the evolution of a branchial circulation.     

Immunocytochemical reaction of a haemocyanin antibody in the midgut gland ofNautilus (Cephalopoda,Tetrabranchiata)

The branchial gland of the dibranchiate cephalopods is described as the site of haemocyanin synthesis. Because there is no equivalent to this organ in tetrabranchiate cephalopods the localization of haemocyanin synthesis remained unknown for a long time. In this study we could confirm the conclusions from prelimnary investigations concerning the copper content of the midgut gland ofNautilus, which gave the first indications for a possible localization of haemocyanin synthesis in this organ. We developed a polyclonal antibody againstNautilus haemocyanin, tested its specificity, and used it on ultra-thin sections of the tissue of the midgut gland. It could be shown that there is a clear imunogold precipitation only on the triangular basal cells in the terminal alveoli. All the other types of cell in this organ were free of any immunoreactivity. It can be supposed that the triangular basal cells in the terminal alveoli of the midgut gland are the sites of haemocyanin synthesis inNautilus.     

Experimental data on the energetic flux during glycolytic oscillations in yeast extracts

Calorimetric experiments were performed on yeast extracts in which glycolytic oscillations were occurring. High metabolic fluxes coincided with low amplitudes and with high frequencies in a temperature range from 283 to 303 K, yielding an activation energy ofE _a=76.8 kJ mol^–1 and a mean Q₁₀ value of 2.5±0.4. The calorimetrically determined reaction enthalpy _fH^0, of the glycolytic catabolism of glucose revealed two distinct groups of extract preparations, with no intermediate values. The values were –107.5±28.7 kJ mol^–1 and –30.8±5.7 kJmol^–1, respectively, while –100.0 kJ mol^–1 was predicted from theoretical calculations. Kreuzberg and Betz⁶ predicted rate limiting effects of GAPDH in oscillating extracts. However, when possible effects of GAPDH on frequency, number of oscillations or total heat production were examined, no influence of increasing or reducing the initial GAPDH concentration could be found. The results are discussed with reference to existing models of glycolytic oscillations.     

Hemodynamics in squid

Summary The difficulties of working on living squid have caused research into their cardiovascular performance to lag behind that done on octopods. Nonetheless, data that we do possess show squid to have cardiovascular capabilities above those of other cephalopods. In general, heart rate, blood pressure and cardiac output is higher for squid than for the other coleoids andNautilus. This higher circulatory system capability is in keeping with squid being relatively large, fast-swimming, pelagic cephalopods.     

Ammonia assimilatory enzymes in a nif−III mutant ofAzotobacter chroococcum

Summary The levels of ammonia assimilatory enzymes have been studied in a nif^–III mutant and a wild strain ofAzotobacter chroococcum grown in media containing different nitrogen sources. It is suggested that the nif^–III mutant may be defective in transport or incorporation of molybdenum.     

Vegetation structure and primary production in acidified lakes in southwestern Sweden

Summary Research during the last two decades has clearly pointed out that dramatic ecosystem changes have occured in lakes due to deposition of acid substances and decreased pH. Today a large number of lakes and running waters in Scandinavia are suffering biological damage with disappearing fish populations, overgrowth of the bottom by mosses and filamentous algae, reduced invertebrate fauna, increased transparency etc.—Of all documented biological changes the effect on macrophyte succession, in particular that ofSphagnum, is the most striking effect. Along with the growth of filamentous algae, these changes have brought about major shifts in the composition of the primary producers. The biomass in one lake was estimated to be 6.5 t (dry wt) corresponding to about 24 g m^–2, the relevant proportions being 52% forSphagnum, 34% forLobelia and 15% forIsoetes. Percentage production in the whole lake is 54% forSphagnum, 29% forLobelia and 17% forIsoetes, which gives an estimated production of 2.9 t yr^–1 or 9 g m^–2 yr^–1.Sphagnum is a recent flora element and its occurrence is related to the acidification of the lakes. The investigations also show that the growth ofLobelia is reduced in acid lakes compared to other oligotrophic lakes due to shading by the benthic mat of filamentous algae, detritus andSphagnum debris.—One can conclude that there are several quantitative and qualitative changes in the macrophyte community which are related to acidification. One can also conclude that liming of lakes cause elimination ofSphagnum and some increase in the production ofIsoetids.     

Die Wirkung von Theophyllin auf den cellulären Ca-Stoffwechsel des Warmblüterherzens

Summary In isolated, electrically driven, left guineapig atria, theophylline (5×10^–4 g/ml) increased the rate of⁴⁵Ca uptake and release without affecting the total myocardial Ca content and the amount of exchangeable cellular Ca. In sheep and calf heart preparations, theophylline (10^–4–10^–3 g/ml) increased Ca inward current during excitation (as examined indirectly by Ca dependent changes of membrane potential in TTX-containing solutions) as well as tension development. It is concluded that the positive inotropic effect of theophylline in mammalian hearts is due to an increase in Ca influx during the excitation process.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

A potent attractant of zoospores ofAphanomyces cochlioides isolated from its host,Spinacia oleracea

A highly potent attractant of zoospores ofAphanomyces cochlioides, a causal fungus of the root rot disease of spinach (Spinacia oleracea), was isolated from spinach roots, and its structure was determined by spectroscopic evidence and chemical synthesis as cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone,1). A chromosorb particle prepared by soaking in solution of1 showed a potent attracting activity toward the zoospores using concentrations of1 above 10^–9 or 10^–10 M.     

Effects of corpora cardiaca extract,furosemide and ion substitution on sodium and chloride flux in perfused Malpighian tubules ofLocusta

Treatment with the co-transport inhibitor, furosemide decreased³⁶Cl^– flux across perfused Malpighian tubules ofLocusta. However, exclusion of³⁶Cl^– from the bathing medium had not effect on²²Na⁺ flux whereas substitution of bathing medium Na⁺ by K⁺ increased³⁶Cl^– flux. Diuretic extract of corpora cardiaca increased²²Na⁺ (by 106%) and³⁶Cl^– (by 335%) fluxes differentially.     

Über eine selektive Mitosehemmung und -schädigung bei jungen Ratten durch Synthalin A

Summary A single subcutaneous injection of synthalin-A does not affect the cytoplasma ofA-cells in pancreatic islets of the rat during the 1^st–5^th day of life, in contrast to adult animals. Selective action was found on mitoticA-cells: reduction of mitotic frequency to 25% of the normal rate, and pathological mitoses in the sense of the so-called primary effect. The mitoses ofB-cells, exocrine pancreatic cells and intestinal epithelia seemed to be unchanged, although the mitotic rate was higher than inA-cells.     

Cell-to-cell transmission in the activation of in situ nematocytes in acontia ofCalliactis parasitica

Summary It is reported that Ca²⁺-induced discharge of in situ nematocytes of acontia ofCalliactis parasitica can occur by cell-to-cell transmission along the acontial filament at a speed that averages 9.8·10^–3 cm^–1. The discharge is preceded by protrusion of nematocytes that proceeds along the acontium at a slightly higher speed.     

Drug interactions in intestinal absorption of3H-digitoxin in rats

Summary The absorption of³H-digitoxin from perfused rat small intestine was inhibited by probenecid (1.0×10^–2 M), ethacrynic acid (0.5×10^–3 M), and mersalyl (8.0×10^–3 M) indicating that digitoxin absorption is at least partly an active process.     

Propriétés antiacétylcholinestérasiques du diiodométhylate debis-(diméthylamino-3-phénoxy)-1-3 propane,de ses dérivés phénoliques et des esters carbamiques correspondants

Summary Thein vitro anti-acetylcholinesterase properties ofbis-(dimethylamino-3-phenoxy)-1-3 propane dimethiodide (2842 CT) of two phenolics derivatives (3443 CT and 3116 CT) and of the two corresponding carbamic esters (3152 CT et 3113 CT) have been compared using human red blood corpuscles as enzyme source; under specified conditions, the Cl-50 are respectively 8 × 10^–7 M for 2842 CT, 3.5 × 10^–9 for the two phenolic compounds, and 1.5 × 10^–9 for the carbamic esters. The potencies of these phenols are very close to those of the carbamates, being a bit higher or lower depending on the concentration of the inhibitor and on the time of the readingThe two phenolic compounds, like 2842 CT, react readily with the enzyme contrarily to the carbamic esters which combine slowly. On the other hand the inhibition by the phenolic derivatives is as stable against washing as that by the carbamates. The carbamates, but not the phenols, show the slow displacement phenomenon.Some of these characteristics are compatible with the hypothesis that carbamic compounds could act through liberated phenolic functions but others indicate that carbamic groups have a role of their own.     

Effects of the adenylate cyclase activator forskolin and its inactive derivative 1,9-dideoxyforskolin on insect cytochrome P-450 dependent steroid hydroxylase activity

The adenylate cyclase activator forskolin and its pharmacologically inactive derivative 1,9-dideoxyforskolin were found to inhibit in a dose-dependent fashion the ecdysone 20-monooxygenase activity associated with wandering stage larvae ofDrosophila melanogaster and fat body and midgut from last instar larvae of the tobacco hornworm,Manduca sexta. The concentrations of these labdane diterpenes required to elicit a 50% inhibition of the cytochrome P-450 dependent steroid hydroxylase activity in the insect tissues ranged from approximately 5×10^–6 to 5×10^–4 M.     

The effect of temperature on the ouabain-sensitivity of Na+−K+-activated ATPase and fluid secretion by the Malpighian tubules ofLocusta

Summary Temperature markedly affected the ouabain-sensitivity of both the Na⁺–K⁺-activated ATPase activity and the secretion of fluid by the Malpighian tubules ofLocusta. Varying the K⁺ concentration in the bathing medium did not affect the ouabain-sensitivity of the fluid secretory process.     

Temperature-dependent activity of mosquito larvicidal factor(s) present inBacillus sphaericus 1593–4 and 1691

Summary The larvicidal factor(s) ofBacillus sphaericus 1593–4 and 1691 was more active at high temperature (33–35 °C) as compared to low temperature (23–25 °C) for the larvae ofCulex fatigans andAnopheles subpictus.     

Variations de l'activité des auxines-oxydases dans les racines duLens

Summary 2, 4-dichlorophenol (DCP), 2, 4-dinitrophenol (DNP) and 2, 4-dinitro-o-cresol (DNC) applied at a concentration of 1.10^–7 to 1.10^–3 M, produce a dramatic increase in IAA-oxidase activity in young cells ofLens root. IAA destruction by breis from root tissues was inhibited by Mn⁺⁺ ion at low concentrations of DCP (1·10^– to 1.10^–7 M), but was enhanced by Mn⁺⁺ ion at higher (1.10^–5 to 1.10^–3 M) DCP levels.

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Ce travail a pu être entreprise grâce à l'appui duFonds national suisse pour la Recherche scientifique.     

Peroxidase-Isoenzyme in Kressekeimlingen (Lepidium sativum L.) und ihre Hemmung durch Silybin,Silydianin und Silychristin

Summary Seedlings ofLepidium sativum L. contain 4 peroxidase isoenzymes. Their de-novo-synthesis is significantly depressed in the presence of 3·10^–3 moles/l silybin, silydianin and silychristin in the incubation medium respectively.     

Die anorganischen Bestandteile des Honigtaues vonMegoura viciae Buckt

Summary In the honeydew ofMegoura viciae Buckt., sucking on the sieve tube sap ofVicia faba, the following cations are present in measurable quantities: potassium (13.0–14.1 mg/ml), sodium (0.04–0.051 mg/ml), magnesium (1.8–2.3 mg/ml) and calcium (0.07–0.09 mg/ml). There are only traces of copper, iron, manganese, zinc, cobalt and molybdenum. Amongst the anions, phosphate was found at 1.9–2.5 and chloride at 0.02–0.05 mg/ml, whereas nitrate and sulphate could not be detected.