Conquering terra firma: The copper problem from the isopod's point of view

Summary 1. Copper is an element of great importance for crustaceans such as isopods and amphipods. While their marine relatives can obtain all necessary chemical components from the surrounding sea water via gills or other epithelia, the species which have conquered terra firma face the problem of extracting practically all vital substances from their food.2. In marine forms, the water flow maintained via ciliary or muscular mechanisms is sufficient to provide several orders of magnitude more copper than required; food probably plays only a minor role in copper supply.3. Terrestrial isopods have to rely entirely on their food as a source of copper. They can do several things in order to ensure an adequate supply: increase food consumption, improve the selective absorption of copper from the food material passing through the gut (possibly in symbiosis with copper concentrating micro-organisms), increase copper stores, thus widening safety margins for times of low supply, reduce copper losses by regulating the transport of this metal between the stores and other body parts.4. It was shown that terrestrial isopods consume about as much food as their marine relatives.5. Extraction of copper from primary vegetable matter seems to be very difficult, both for terrestrial forms likePorcellio scaber and for intertidal forms such asLigia oceanica or the amphipodOrchestia gammarella; extraction is possible only at very high copper concentrations.6. A way out of this calamitous situation seems to be in cooperation with micro-organisms which liberate copper from the tightly bound states in which it exists in the primary plant material. This is true forP. scaber but it probably also holds forO. gammerella, L. oceanica and other species feeding on decaying algae on the shore.7. The amount of copper stored in the hepatopancreas increases with increasing dependence of the species on the terrestrial environment, the values obtained for intertidal species being intermediate between marine and truly terrestrial species.8.P. scaber (and probablyOniscus asellus) will extract up to 95% of the copper present in artificially enriched leaf litter whereas intertidal forms feeding onFucus will not extract more than 50%, mostly only 20% or less, from artificially enriched seaweeds.9. Copper is more strictly relegated to storage cells of the hepatopancreas in terrestrial isopods than it is in marine or intertidal ones. Extensive movements of copper inP. scaber are accompanied by the synthesis of special carrier proteins, whereas in marine or intertidal species this metal seems to be able to move more freely in an easily dissociable state between the storage cells and other cells of the hepatopancreas.

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Eroberung des Festlands: Das Kupferproblem vom Gesichtspunkt der Isopoden

Kurzfassung Marine Crustaceen müßten theoretisch in der Lage sein, dem Atemwasser genügend viel Kupfer zu entnehmen, um selbst schwerste tägliche Verluste zu ersetzen. Im Vergleich dazu dürfte das in der Pflanzennahrung angebotene Cu mengenmäßig eine nur geringe Rolle spielen. Dennoch muß das vegetabilische Cu ausreichen, um den Bedarf herbivorer terrestrischer Crustaceen an diesem Metall zu decken. Die Probleme, die im Zusammenhang mit der Immigration vom Meer zum Land hinsichtlich der Kupferversorgung entstehen, werden am Beispiel litoraler und terrestrischer Isopoden und Amphipoden — zum Teil in spekulativer Form — diskutiert. Vergleichende Untersuchungen haben ergeben, daß terrestrische und litorale Isopoden die Menge der aufgenommenen Nahrung gegenüber marinen Arten nicht erhöhen und daß die Assimilation von Cu aus der Nahrung in ausreichender Weise nur durch die Beihilfe von Mikroorganismen möglich zu sein scheint. Der Zugang zu einem nährstoffreichen, von Mikroorganismen gut durchgearbeitetem Substrat muß also eine der Hauptvoraussetzungen für eine funktionierende Kupferversorgung aus pflanzlichem Material sein. Außerdem nimmt die Menge des im Hepatopancreas gespeicherten Cu in der Reihe marine — litorale — terrestrische Crustaceen zu. Auch die Leistungsfähigkeit der Kupferassimilation ist im Vergleich zu litoralen bei terrestrischen Isopoden größer. Während beiPorcellio scaber die Kupferassimilation in direkter Abhängigkeit vom Kupfergehalt der Nahrung steht und Werte über 90% erreichen kann, beträgt beiLigia oceanica undOrchestia gammarella die Kupferassimilation bei mittlerem Kupfergehalt (0,2 bis 0,3µg/mg Trockengewicht) nur etwa 66%, um dann wieder abzunehmen. Schließlich wird im Vergleich zu marinen und litoralen Isopoden der Kupferstoffwechsel terrestrischer Isopoden besser geregelt, indem Cu ausschließlicher in besonderen Zellen gespeichert und jede umfangreiche Mobilisierung des Metalls von der Synthese charakteristischer Sekrete begleitet wird, die Stoffe (wahrscheinlich Proteide) enthalten, deren Aufgabe zu sein scheint, freies Cu zu binden. Dies würde sowohl dessen toxische Eigenschaften reduzieren, als auch Verluste dieses Metalls an das Blut und in das Darmlumen verhindern.

     

MHC class II invariant chains in antigen processing and presentation

Most protein antigens cannot elicit a T-cell response unless they are processed to peptides, which are then presented to T lymphocytes by surface MHC class II molecules. Recent evidence supports an essential role of the invariant chain associated with class II MHC polypeptides in antigen processing.     

Intra- and interspecies analyses of the carcinoembryonic antigen (CEA) gene family reveal independent evolution in primates and rodents

Summary Various rodent and primate DNAs exhibit a stronger intra- than interspecies cross-hybridization with probes derived from the N-terminal domain exons of human and rat carcinoembryonic antigen (CEA)-like genes. Southern analyses also reveal that the human and rat CEA gene families are of similar complexity. We counted at least 10 different genes per human haploid genome. In the rat, approximately seven to nine different N-terminal domain exons that presumably represent different genes appear to be present. We were able to assign the corresponding genomic restriction endonuclease fragments to already isolated CEA gene family members of both human and rat. Highly similar subgroups, as found within the human CEA gene family, seem to be absent from the rat genome. Hybridization with an intron probe from the human nonspecific cross-reacting antigen (NCA) gene and analysis of DNA sequence data indicate the conservation of noncoding regions among CEA-like genes within primates, implicating that whole gene units may have been duplicated. With the help of a computer program and by calculating the rate of synonymous substitutions, evolutionary trees have been derived. From this, we propose that an independent parallel evolution, leading to different CEA gene families, must have taken place in, at least, the primate and rodent orders.     

Sun compass orientation in seed-caching scrub jays (Aphelocoma coerulescens)

Summary In their natural environment, scrub jays harvest pinyon pine seeds and store them in subterranean caches. In our tests, the birds performed this behavior in an octagonal outdoor aviary with sand-filled cups inserted in the floor. For caching, only 12 such cups in a 90° sector were available, while for the recovery session 4 to 6 days later all 48 cups in the entire aviary were open. In control tests, the birds concentrated their search in the sector where the seeds had been cached. When the internal clock of the birds was shifted 6 h between caching and recovery, they preferentially probed in the adjacent 90° sector. This indicated that they used sun compass information to relocate their caches, largely ignoring visual cues from surrounding landmarks.The dominant role of the sun compass which has a parallel in the orientation of homing pigeons, may reflect a general tendency to prefer compass information in spatial orientation tasks; it is in agreement with the model that birds generally have a directionally oriented view of space.Abbreviations OR Original caches - SH shifted caches     

Elicitor-induced metabolic changes in cell cultures of chickpea (Cicer arietinum L.) cultivars resistant and susceptible to Ascochyta rabiei

Cell-suspension cultures of two chickpea (Cicer arietinum L.) cultivars, resistant (ILC 3279) and susceptible (ILC 1929) to the fungus Ascochyta rabiei (Pass.) Lab., showed differential accumulation of the phytoalexins medicarpin and maackiain, and transient induction of related enzyme activities after application of an A. rabiei-derived elicitor. The chalcone-synthase (CHS) activity (EC 2.3.1.74) which is involved in the first part of phytoalexin biosynthesis exhibited a maximum 8–12 h after elicitation in the cells of both cultivars. Concomitant with the fivefold-higher phytoalexin accumulation, CHS activity increased twofold in the cells of the resistant cultivar. The maximum of the elicitor-induced CHS-mRNA activity was determined 4 h after onset of induction in the cultures of both cultivars, although in cells of cultivar ILC 3279 this mRNA activity was induced at a level twofold higher than that in cells of the susceptible race ILC 1929. Investigations of CHS isoenzymes by two-dimensional gel electrophoresis of immunoprecipitated in-vitro-translated protein indicated the presence of five proteins. In the cells of both cultivars only two of the isoenzymes were induced after elicitor treatment. Analysis of the total in-vitro-translated proteins by two-dimensional gel electrophoresis showed that the constitutively expressed patterns of mRNA activities in the cell cultures of the two cultivars were identical. After elicitation, considerably more translatable mRNAs were induced in the cells of cultivar ILC 3279. The few induced proteins, and their respective mRNA activities, which could be detected in the cells of the susceptible cultivar, all existed in the cells of the resistant cultivar, too. One highly induced protein (M_r 18 kDa) found in the cells of cultivar ILC 3279 reached its maximum mRNA activity 6 h after elicitor application. The amount of this protein was hardly increased in the cells of the susceptible cultivar. This protein appears to be excreted from the cells into the growth medium.Abbreviations CHS chalcone synthase - IEF isoelectric focussing - ILC international legume chickpea - PR-protein pathogenesis-related protein - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis Financial support by Deutsche Forschungsgemeinschaft and Fonds der Chemischen Industrie is gratefully acknowledged. The authors thank Dr. K. Hahlbrock (Max-Planck-Institut für Züchtungsforschung, Köln, FRG) for provision of antisera and the International Centre for Agricultural Research in the Dry Areas (Aleppo, Syria) for plant material.     

Development of chicken embryos in a pulsed magnetic field

Six independent experiments of common design were performed in laboratories in Canada, Spain, Sweden, and the United States of America. Fertilized eggs of domestic chickens were incubated as controls or in a pulsed magnetic field (PMF); embryos were then examined for developmental anomalies. Identical equipment in each laboratory consisted of two incubators, each containing a Helmholtz coil and electronic devices to develop, control, and monitor the pulsed field and to monitor temperature, relative humidity, and vibrations. A unipolar, pulsed, magnetic field (500-microseconds pulse duration, 100 pulses per s, 1-microT peak density, and 2-microseconds rise and fall time) was applied to experimental eggs during 48 h of incubation. In each laboratory, ten eggs were simultaneously sham exposed in a control incubator (pulse generator not activated) while the PMF was applied to ten eggs in the other incubator. The procedure was repeated ten times in each laboratory, and incubators were alternately used as a control device or as an active source of the PMF. After a 48-h exposure, the eggs were evaluated for fertility. All embryos were then assayed in the blind for development, morphology, and stage of maturity. In five of six laboratories, more exposed embryos exhibited structural anomalies than did controls, although putatively significant differences were observed in only two laboratories (two-tailed Ps of .03 and less than .001), and the significance of the difference in a third laboratory was only marginal (two-tailed P = .08). When the data from all six laboratories are pooled, the difference in incidence of abnormalities in PMF-exposed embryos (approximately 25 percent) and that of controls (approximately 19 percent), although small, is highly significant, as is the interaction between incidence of abnormalities and laboratory site (both Ps less than .001). The factor or factors responsible for the marked variability of inter-laboratory differences are unknown.     

Different influences of cytochalasin B on the activation of human neurophils settled onto petri dishes displayed by simultaneously detected native and luminol-dependent luminescence

Cytochalasin B (CB) is known to interfere reversibly with the cytoplasmic contractile filamental network of mammalian cells. The role of the microfilament system in the mechanism of the reactive oxygen intermediates release of polymorphonuclear leukocytes (PMNL) was studied for different kinds of stimuli. PMNL from fresh human blood were treated with CB and stimulated by adherence on plastic surfaces, by opsonized zymosan, by phorbol myristate acetate and by N-formylmethionyl-phenylalaline. The production of reactive oxygen species were monitored by simultaneous detection of native, luminol-independent, luminescence (NL) and luminol-dependent luminescence (LDL) using a method of spectral discrimination. Different influences of CB on NL with respect to LDL as well stimuli-dependent influences of CB on the luminescence response of PMNL were observed. Especially phagocytosis-associated activation of PMNL was strongly inhibited by CB, whereas LDL was reduced to a much greater extent in comparison with NL. A firm involvement of the microfilament system is indicated, but it depends on the kind of stimulus engaged.     

Langzeit-Erfassung brutbiologischer Parameter beim KleiberSitta europaea in zwei norddeutschen Untersuchungsr?umen

Zusammenfassung Der Zusammenstellung liegen Befunde zu den brutbiologischen Parametern Gelegestärke, Schlüpftermin und Anzahl flügger Junge zugrunde, die von 1970–1995 an rund 1500 Erstbruten des Kleibers in Versuchsgebieten mit künstlichen Nisthöhlen bei Braunschweig und Essen gewonnen wurden. Die Vollgelege-Eizahl beträgt im Durchschnitt 6,8 Eier (nur Daten aus dem Braunschweiger Raum), der durchschnittliche Schlüpftermin fällt auf den 9. Mai (Braunschweig) und 6. Mai (Essen) und die Anzahl flügger Nestlinge liegt in erfolgreichen Bruten im Mittel bei 5,6 (Braunschweig) bzw. 5,2 (Essen). Im Untersuchungszeitraum kam es in beiden Gebietsregionen zu einer signifikanten Verfrühung des Bruttermins. Doch werden wohl erst die Befunde der kommenden Jahre zeigen können, ob die rezente Häufung früher Brutjahre beim Kleiber (diese Arbeit) und bei Kohl- und Blaumeisen (Winkel &Hudde unveröff.) bereits eine Folge des anthropogen bedingten global warming ist oder noch das normale Auf und Ab der Witterung widerspiegelt.

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Long-term changes of breeding parameters of NuthatchesSitta europaea in two study areas of northern Germany

Between 1970 and 1995, nestbox data about clutch size, hatching date and fledging success were collected for a total of around 1500 first broods of Nuthatches in two north German study areas (near Brunswick 52.16 N 10.32 E and near Essen 51.24 N 6.59 E). The average clutch size was 6.8 eggs (Brunswick), the average hatching date 9 May (Brunswick) and 6 May (Essen), and the mean number of fledglings per successful brood 5.6 (Brunswick) and 5.2 (Essen). Over time hatching dates significantly advanced in both areas. Data of further years are needed to clarify if the recent unusual sequence of early breeding years in the Nuthatch is already a consequence of the anthropogenic greenhouse effect or just due to normal variation of weather conditions.

     

Gliding motility in slide cultures of Myxococcus xanthus in stable and steep chemical gradients.

A method was devised to construct stable and steep chemical gradients in slide cultures to study the movements of gliding cells. The movement of Myxococcus xanthus individual cells and small swarms was studied in these gradients. There was no response to gradients of Casitone and yeast extract that were previously reported to stimulate a positive chemotactic response with M. xanthus.