Fine structural relation between pancreatic excretory ductules and intercellular spaces

Summary Horse-radish peroxidase injected into the femoral vein of intact rats, or infused at 30 cm H₂O pressure into the main pancreatic duct of intact dogs, entered easily the interstitial spaces surrounding acini and acinar cells. The latter are interconnected at their luminal segments by zonulae occludentes. These junctions form a barrier to tracer penetrating from the interstitium towards the lumen of terminal ductules. However, the intraductally infused peroxidase entered the interstitial spaces, probably through the pressure injured acinar cells, as did colloidal carbon particles when infused intraductally.     

Fine structrual relation between pancreatic excretory ductules and intercellular spaces.

Horse-radish peroxidase injected into the femoral vein of intact rats, or infused at 30 cm H2o pressure into the main pancreatic duct of intact dogs, entered easily the interstitial spaces surrounding acini and acinar cells. The latter are interconnected at their luminal segments by zonulae occuldentes. These junctions form a barrier to tracer penetrating from the interstituim towards the lumen of terminal ductules. However, the intraductally infused peroxidase entered the interstitial spaces, probably through the pressure injured acinar cells, as did colloidal carbon particles when infused intraductally.     

Hemolymph regulation to hyposaline and hypersaline conditions inGammarus oceanicus (Crustacea: Amphipoda)

Summary Specimens ofGammarus oceanicus were exposed to sea water at salinities of 3%. and 55%. for various periods of time up to 24 h.G. oceanicus can regulate in hyposaline sea water and reached a new steady state after 4 h exposure to 3%. sea water. Its ability to regulated in hypersaline conditions is limited and no animals survived longer than 6–8 h in 55%. sea water. These results are discussed with respect to salinity conditions in the intertidal zone.Acknowledgments. Financial assistance from the University of New Brunswick Research Fund to K.H. is gratefully acknowledged.     

Exchange of water between the harbor porpoise,Phocoena phocoena,and the environment

Summary During determination of total body water and net water turnover in the harbor porpoise,Phocoena phocoena, it was demonstrated that the porpoise exchanged water with an isosmotic environment by way of free diffusion and with hypo- or hyperosmotic environment by way of osmosis.     

Pharyngeal cavity and the gills are the target organ for the repellent action of pardaxin in shark

Summary Pardaxin, an active principle of the repellent secretion of the Red Sea flatfish,Pardachirus marmoratus, elicited severe struggling, mouth paralysis, and transient increase in urea leakage from the gills only when administered to the medium bathing the shark's pharyngeal cavity and gills. An apparatus was constructed which prevents a mixing of the outflow from shark's gills with water bathing its surface skin. It is concluded that in sharks the gills and/or the pharyngeal cavity are the target organ for the repellent action of pardaxin.     

On the residual water content of dried but viable cells

Summary We have examined the residual water in dried cysts of the brine shrimp,Artemia salina, by gas-bombardment techniques at reduced pressures and temperatures. This treatment reduced, but did not remove all the residual water, the lower limit being about 0.0069 gH₂O/g dried weight. The significance of such small amounts of water to cell hydration is assessed. The treatment did not appreciably reduce the viability of this cyst population.Supported in part by grant PCM-24037 from the US National Science Foundation.     

Sex pheromone conversion and degradation in antennae of the silkworm mothBombyx mori L.

Summary In living antennae of the silkworm mothBombyx mori L. the pheromone compound (E, Z)-10,12-hexadecadienol and hexadecanol are enzymatically converted to their corresponding fatty aldehydes, acids and long-chain fatty acid esters. The pheromone is completely degraded at high rates in the antennae of freshly hatched moths. The polar volatile [³H]metabolites exclusively consist of tritiated water. The half-life of the pheromone is about 2.5 min in males and 0.5 min in females. Drying inactivates the enzymes responsible for pheromone oxidation.Dedicated to Professor Adolf Butenandt on the occasion of his 85th birthday     

Über die Reizung des Ferntastsinns bei Fischen und Amphibien

Summary Fishes and aquatic amphibians are able to detect and locate moving bodies and even obstacles at some distance by means of their lateral-line sense organs (Ferntastsinn). As was shown experimentally, the main physical process involved in these reactions are certain local damming phenomena in front of the moving object (rise of pressure, displacement of water particles). Obstacles cause an alteration of the damming phenomena produced by the moving animal's body itself (increase of water resistance).Kramer's different view is rejected; he overlooked the existence of damming phenomena and was not aware of the fact thatXenopus laevis reacts to surface waves even when the animal is totally submerged.     

Diurnal and seasonal rhythms of stridulatory activity in the water boatmenCorixa dentipes andCorixa punctata

Summary Two species of water boatmen which live sympatrically in Central Europe, begin stridulatory activity in the autumn. But whereas the activity ofC. punctata is maximal during autumn, the peak activity ofC. dentipes occurs in the spring.Supported by Deutsche Forschungsgemeinschaft, SFB 4 Regensburg.     

NMR structures of the C-terminal end of human complement serine protease C1s

Synthetic peptides derived from the C-terminal end of the human complement serine protease C1s were analysed by circular dichroism and nuclear magnetic resonance (NMR) spectroscopy. Circular dichroism indicates that peptides 656-673 and 653-673 are essentially unstructured in water and undergo a coil-to-helix transition in the presence of increasing concentrations of trifluoroethanol. Two-dimensional NMR analyses performed in water/trifluoroethanol solutions provide evidence for the occurrence of a regular α-helix extending from Trp659 to Ser668 (peptide 656-673), and from Tyr656 to Ser668 (peptide 653-673), the C-terminal segment of both peptides remaining unstructured under the conditions used. Based on these and other observations, we propose that the serine protease domain of C1s ends in a 13-residue α-helix (656Tyr-Ser668) followed by a five-residue C-terminal extension. The latter appears to be flexible and is probably locked within C1s through a salt bridge involving Glu672. Received 19 November 1997; accepted 24 November 1997     

Effects of water acidification on the distribution pattern and the reproductive success of amphibians

Summary Nine amphibian species were encountered in poorly buffered waters of The Netherlands (alkalinity 1 meq·l^–1). These soft water systems are highly sensitive to acidifying precipitation. The number of species as well as the percentage of waters which harbour amphibian populations are strongly reduced in the extremely acid pH-class . The reproductive success of amphibians is negatively affected by low pH. The eggs become heavily infested with fungi (Saprolegniaceae). In acidifying systems many physico-chemical parameters are significantly correlated with the pH of the water. Strongly acidified waters are characterized by low alkalinity, conductivity and ionic content but high acidity and high concentrations of (heavy) metals and ammonium and a high relative sulphate concentration. Culture experiments with eggs and larvae ofRana arvalis. Rana esculenta, Rana temporaria andBufo bufo show that apart from the pH, elevated aluminium, cadmium and ammonium contents may also affect the reproductive success of amphibians.     

Body size variability and water balance: A comparison between mainland and island populations ofMastomys huberti (Rodentia: Muridae) in Senegal

Generally rodents are found to be larger on islands than on the mainland. However, there are some exceptions to this rule, and the aim of this paper is to examine one of them. On the mainland of Senegal,Mastomys huberti occupies humid habitats. However, it occurs also on dry and sandy islands (Saloum delta), where its representatives are dwarf. Since water availability appeared to be the limiting factor in these islands when compared to the mainland, we studied water turnover characteristics in relation to body size, in mainland and island populations at the end of the dry season, under both field and laboratory conditions. All populations were found to be water balanced in their natural habitats. They presented similar rates of water turnover, even though island animals were subjected to stronger constraints than mainland ones. Laboratory experiments suggested that the physiological plasticity of one of the island populations may be reduced. Island populations have a higher kidney size to body weight ratio than those from the mainland. We propose that smaller size in the islands allows the maintenance of water balance with a smaller amount of water, and that a higher ratio of kidney filtration surface to body size may helpMastomys huberti to survive in dry islands. We discuss the factors responsible for body size variability and variation in water exchange characteristics and conclude that different factors could explain body size variation among island populations, depending on the species considered and the ecological constraints met within the islands.     

The occurrence and physiological functions of melatonin in the most primitive eumetazoans,the planarians

Asexual planarians of the speciesDugesia dorotocephala exhibit a distinct circadian rhythm of fissoning (asexual reproduction) under the influence of normal photoperiod; fissioning occurs only at night. This rhythm is broken down by continuous illumination, continuous darkness or by decapitation. The fissioning rate increases when planarians are exposed to light for less than 1 hour/day or when they are decapitated. Fissioning of decapitated planarians is suppressed by continuous treatment with melatonin, whereas fissioning resumes when these are returned to normal culture water. Interestingly, fissioning occurs at night when decapitates are treated with melatonin in the daytime, while it is observed in the daytime with night-time melatonin treatment. Endogenous melatonin was detected by HPLC and RIA. The endogenous melatonin level is always higher in those heads collected in the scotophase than in those collected in the photophase. A type of neurosecretory cell, which may synthesize melatonin, is found in the assembly of photoreceptor cells.     

A chromosome study of the parthenogenetic rice water weevil,Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), in Japan

Summary The chromosomes of the so-called rice water weevil,Lissorhoptrus oryzophilus, Kuschel obtained from Tokoname City, Aichi Prefecture, were studied in both oogonial and oocyte-maturation divisions in squash and sectioned slides, respectively. The chromosome number was confirmed as exactly 33 in both divisions. No reduction division takes place. It is therefore concluded thatLissorhoptrus oryzophilus is a parthenogenetic triploid in Tokoname City.     

Enzymatic processing of pheromones and pheromone analogs

Summary Pheromone perception requires rapid enzymatic degradation of the active chemical signal in the sensory hairs. Three insects are used to illustrate chemical approaches to studying the degradation of pheromones by antennal enzymes. First, hydrolysis of acetate and haloacetate esters is examined in the diamondback moth,Plutella xylostella. Second, aldehyde oxidation and the selective inhibition of the oxidase and dehydrogenase activities are described for the tobacco budworm moth,Heliothis virescens. Finally, a stereochemical analysis of the epoxide-hydrase catalyzed addition of a water molecule to the oxirane ring of disparlure is described for the gypsy moth,Lymantria dispar.     

Natriuretic peptide hormones promote radial water movements from the xylem of Tradescantia shoots

Immunological evidence suggests that plants, like vertebrates, contain natriuretic peptides (NPs) and that rat atrial NP (rANP) binds specifically to plant membranes and promotes concentration and conformation-dependent stomatal opening. Stomatal opening and specific increases in cGMP levels were also observed in response to immunoreactive plant NP (irPNP). Here we report that both 1 μM rANP and irPNP (100 ng total protein/100 μL) significantly increase radial water movements out of the xylem of shoots of Tradescantia multiflora. Enhanced radial water movements are also observed in response to the cell permeant cGMP analogue 8-Br-cGMP (100 nM). The water channel inhibitor mercuric chloride (HgCl₂) significantly inhibits radial water movements at concentrations of 50 μM, while the presence of 10 μM 2-hydroxyethylmercaptoethanol (ME) prevents the inhibitory effect of the mercurial. The guanylate cyclase inhibitor LY 83583 at a concentration of 20 μM and sodium azide (NaN₃) at concentrations of ≥ 1 μM both also reduce radial water movements. We therefore conclude that the regulation of radial water movement out of the xylem involves modulation of cGMP levels, water channels and respiration-dependent processes. In addition, we propose that NPs have a critical role to play in radial water movements out of the xylem and speculate that as in vertebrates, NP effects might, at least in part, be mediated via the regulation of guanylate cyclases and water channels. Received 15 June 1998; received after revision 7 August 1998; accepted 26 August 1998     

Eine Feldmethode zur Wasseruntersuchung mit Ionenaustauschern

Summary A procedure for rapid investigations of water is described. After measurement of thep _H and determination of the alcalinity the cations are exchanged for H-ions in a bed of a synthetic resin exchanger. These are determined by titration with NaOH. Further data may be calculated approximately.     

Toxicity of Temik (aldicarb) for a fresh water teleost,Barbus conchonius Hamilton

Summary The toxic effects of Temik (aldicarb) on a fresh water Himalyan lake teleost,Barbus conchonius were investigated in hard and soft water. The 48-, 72- and 96-h TL_m-values in mg/l were 8.99, 2.39 and 2.42 respectively in the hard-water test and 3.30, 0.62 and 0.46 in the soft-water test. The toxicity of Temik toB. conchonius increases many fold in soft water.One of us (S. C. P.) is grateful to U. G. C., for the award of a senior research fellowship.     

Klangspektrographische Untersuchung der Lautäusserung beim Krallenfrosch,Xenopus laevis

Summary Three different calls of the clawed toadXenopus laevis are described and their sound spectrograms are presented. The male and female have one characteristic call each, which is heard during clasping after stimulating the mating behaviour with chorionic gonadotropin. A second call of the male is heard without hormone treatment, often after feeding or change of water.     

Influence of chemical signals on the topographic orientation of the cave fishCaecobarbus geertsi Boulenger (Pisces,Cyprinidae)

Summary Adult individuals of the cave cyprinidCaecobarbus geertsi Boulenger, when placed in a choice-apparatus, show a significant tendency to orient towards the zone in which water from a tank occupied by known conspecifics is introduced. The phenomenon is briefly discussed in relation to the physical features of the subterranean biotopes.Research supported by the Centro di Studio per la Faunistica ed Ecologia Tropicali del Consiglio Nazionale delle Ricerche.