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Showing papers in "Naturwissenschaften in 1998"


Journal ArticleDOI
TL;DR: It is concluded that molecular biological studies with sponges as model will not only help to understand the evolution of Protoctista to Metazoa but also the complex, hierarchial regulatory network of cells in higher metazoa.
Abstract: , which code for proteins. The analyses of their deduced amino acid sequences allowed a molecular biological approach to solve the problem of monophyly of Metazoa. Molecules of the extracellular matrix/basal lamina, with the integrin receptor, fibronectin, and galectin as prominent examples, cell-surface receptors (tyrosine kinase receptor), elements of sensory systems (crystallin, metabotropic glutamate receptor), and homologs/modules of an immune system (immunoglobulin like molecules, scavenger receptor cysteine-rich, and short consensus repeats, rhesus system) classify the Porifera as true Metazoa. As living fossils, provided with simple, primordial molecules allowing cell-cell and cell-matrix adhesion as well as processes of signal transduction as known in a more complex manner from higher Metazoa, they also show peculiarities not known in other metazoan phyla. Tissues of sponges are rich in telomerase activity, suggesting a high plasticity in the determination of cell lineages. It is concluded that molecular biological studies with sponges as model will not only help to understand the evolution of Protoctista to Metazoa but also the complex, hierarchial regulatory network of cells in higher Metazoa.

130 citations


Journal ArticleDOI
TL;DR: A Jurassic turtle, K.557 chelys aprix from the Early Jurassic of North America, also possesses four pairs of pores on inframarginal scales, establishing Rathke’s gland as the oldest amniote skin gland.
Abstract: 557 chelys aprix from the Early Jurassic of North America [11], also possesses four pairs of pores on inframarginal scales (Fig. 2). These pores in K. aprix establish Rathke’s gland as the oldest amniote skin gland. We are unable to document Rathke’s gland pores in several extinct taxa, including the oldest pleurodire, Proterochersis robusta from the Late Triassic of Germany [12], and a variety of cryptodire groups (Fig. 1). Neither do we observe gland pores in the most primitive turtle, Proganochelys quenstedti from the Late Triassic of Germany [13]. Aside from the obscurity of gland pores, determining the presence of Rathke’s gland in some extinct taxa is problematic because the developed skeletal components through which gland ducts would otherwise pass en route to the shell bridge or skin are lacking.

117 citations


Journal ArticleDOI
TL;DR: The aim of this paper was to determine which esters are involved in the inhibition of ovary development of caged bees and to test whether these compounds maintain their effect under natural conditions.
Abstract: In honeybee queenright colonies, ovary development in workers is inhibited by queen-produced pheromones [1–4] and by the presence of the brood [5]. It seems that the presence of the unsealed brood provides an inhibitory signal stronger than the queen’s pheromone [6]. When administered orally with honey, the ethyl alcohol or acetone extracts prepared from unsealed honey bee brood show inhibitory effects on worker ovary development [7]. More recent results show that a mixture of ten fatty acid esters (methyl and ethyl esters of palmitic, linoleic, linolenic, stearic, and oleic acids) present naturally on the larval cuticle [8] induce a strong inhibitory effect on ovary development of caged bees in controlled conditions. This inhibition occurs by contact, diffusion, or ingestion of the blend [9]. Based on this preliminary work, the aim of this paper was to determine which esters are involved in the inhibition of ovary development of caged bees and to test whether these compounds maintain their effect under natural conditions. First we screened the efficiency of different esters. For this purpose each ester was mixed individually in food (bee candy: mixture of honey and powdered sugar) at a concentration of 10 (wt/wt) and was tested under controlled conditions on newly emerged bees (Apis mellifera mellifera). Each group of 120 bees was placed in a 12!10!4 cm cage, provided with a vial of tap water, pollen,

114 citations


Journal ArticleDOI
TL;DR: Evaluation of electrical and chemical brain stimulation data, lesioning studies, single-neurone recordings, and neuroanatomical tracing work leads to the following conclusions: the periaqueductal gray and laterally bordering tegmentum of the midbrain represent a crucial area for the production of vocalization.
Abstract: Squirrel monkey vocalization can be considered as a suitable model for the study in humans of the neurobiological basis of nonverbal emotional vocal utterances, such as laughing, crying, and groaning. Evaluation of electrical and chemical brain stimulation data, lesioning studies, single-neurone recordings, and neuroanatomical tracing work leads to the following conclusions: The periaqueductal gray and laterally bordering tegmentum of the midbrain represent a crucial area for the production of vocalization. This area collects the various vocalization-triggering stimuli, such as auditory, visual, and somatosensory input from diverse sensory-processing structures, motivation-controlling input from some limbic structures, and volitional impulses from the anterior cingulate cortex. Destruction of this area causes mutism. It is still under dispute whether the periaqueductal region harbors the vocal pattern generator or merely couples vocalization-triggering information to motor-coordinating structures further downward in the brainstem. The periaqueductal region is connected with the phonatory motoneuron pools indirectly via one or several interneurons. The nucleus retroambiguus represents a crucial relay station for the laryngeal and expiratory component of vocalization. The articulatory component reaches the orofacial motoneuron pools via the parvocellular reticular formation. Essential proprioceptive feedback from the larynx and lungs enter the vocal-controlling network via the solitary tract nucleus.

109 citations



Journal ArticleDOI
TL;DR: A comparison of the polarization pattern of freshwater habitats recorded by video polarimetry in red, green and blue spectral ranges and its relevance for water detection by aquatic insects and the sensitivities of dragonfly photoreceptors is presented.
Abstract: 1. Kennedy CH (1917) Notes on the life history and ecology of the dragonflies (Odonata) of central California and Nevada. Proc US Nat Mus 52 :483 2. Puschnig R (1926) Albanische Libellen. Konowia 5 :33, 113, 208, 313 3. Fraser FC (1936) The Fauna of British India. Odonata, vol 3. Taylor and Francis, London 4. Whitehouse FC (1941) A guide to the study of dragonflies of Jamaica. Bull Inst Jamaica Sci Ser no 3, pp 69 5. Kennedy CH (1938) The present status of work on the ecology of aquatic insects as shown by the work on the Odonata. Ohio J Sci 38 :267 6. Horváth G, Zeil J (1996) Kuwait oil lakes as insect traps. Nature 379 :303 7. Schwind R (1985) Sehen unter und über Wasser, Sehen vom Wasser: Das Sehsystem eines Wasserinsektes. Naturwissenschaften 72 :343 8. Schwind R (1991) Polarization vision in water insects and insects living on a moist substrate. J Comp Physiol A 169 :531 9. Schwind R (1995) Spectral regions in which aquatic insects see reflected polarized light. J Comp Physiol A 177 :439 10. Angus PB (1973) Pleistocene Helophorus (Coleoptera, Hydrophilidae) from Borislav and Starunia in the Western Ukraine, with a reinterpretation of M. Somnicki’s species, description of a new Siberian species and comparison with British Weichselian faunas. Phil Trans R Soc London 265 :299 11. Akersten WA, Shaw CA, Jefferson GT (1983) Rancho La Brea: status and future. Paleobiology 9 :211 12. Kowalski K (1997) Starunia. In: Lagerstaetten of Europe. European Palaeontological Association, Milan 13. Southwood TRE (1966) Ecological Methods. Chapman & Hall, London 14. Horváth G, Varjú D (1997) Polarization pattern of freshwater habitats recorded by video polarimetry in red, green and blue spectral ranges and its relevance for water detection by aquatic insects. J Exp Biol 200 :1155 15. Laughlin SB (1976) The sensitivities of dragonfly photoreceptors and the voltage gain of transduction. J Comp Physiol 111 :221 16. Laughlin S, McGinness S (1978) The structure of dorsal and ventral regions of a dragonfly retina. Cell Tissue Res 188 :427 17. Kirk WDJ (1984) Ecologically selective coloured traps. Ecol Entomol 9 :35 18. Horváth G, Pomozi I (1997) How celestial polarization changes due to reflection from the deflector panels used in deflector loft and mirror experiments studying avian navigation. J Theor Biol 184 :291 19. Wildermuth H, Spinner W (1991) Visual cues in oviposition site selection by Somatochlora arctica (Zetterstedt) (Anisoptera: Corduliidae). Odonatologica 20 :357 20. Wildermuth H (1993) Habitat selection and oviposition site recognition by the dragonfly Aeshna juncea (L.): an experimental approach in natural habitats (Anisoptera: Aeshnidae). Odonatologica 22 :27 21. Wildermuth H (1998) Dragonflies recognize rendezvous and oviposition sites by horizontally polarized light: a behavioural field test. Naturwissenschaften (submitted) 22. Schwind R, Horváth G (1993) Reflection-polarization pattern at water surfaces and correction of a common representation of the polarization pattern of the sky. Naturwissenschaften 80 :82 23. Horváth G (1995) Reflection-polarization patterns at flat water surfaces and their relevance for insect polarization vision. J Theor Biol 175 :27 24. Corbet PS (1962) A Biology of Dragonflies. Witherby, Warwick 25. Muller HRA (1937) Een zonderlinge vergissing van Copera marginipes. De Troopische Natuur 26 :95 26. Wyniger R (1955) Beobachtungen über die Eiablage von Libellula depressa (L.) (Odonata, Libellulidae). Mitt Ent Ges Basel NF 5 :62 27. Neville P (1960) A list of Odonata from Ghana, with notes on their mating, flight, and resting sites. Proc R Ent Soc London A 35 :124 28. Noordwijk, M. V (1980) Dragonfly behaviour over shining surfaces. Notul Odonatol 1 :105 29. Fränzel U (1985) Öko-ethologische Untersuchungen an Cordulegaster bidentatus Selys, 1843 (Insecta: Odonata) im Bonner Raum. Thesis, University Bonn

101 citations


Journal ArticleDOI
TL;DR: Only a few countries have established sufficiently reliable programs for monitoring songbirds during the breeding period, and the results of a full quarter of a century of songbird population monitoring are reported on.
Abstract: During the past century a decline hasbeen noted in European bird popula-tions, both in large species [1] andpossibly also in songbirds [2]. Todaythe “Red List” (of endangered spe-cies) includes about 50% of the avi-fauna in most Central Europeancountries; about 30% of species aredeclining to an extent that threatenstheir continued existence in CentralEurope. These include songbirds,mainly open-country species that areeasy to monitor. Trends in the num-bers of many unobtrusive songbirdspecies, however, have remainedlargely unclear [3]. To assess theirpopulation changes our institute be-gan a census program in 1972 with thehelp of hundreds of amateur ornitho-logists [4]. A trapping station in thisproject in southern Germany has pro-vided data on 35 species over 25 years– the first dataset based on strictlystandardized methods over such along period. During this entire periodthe number of trapped birds has fall-en slowly but continuously, by an av-erage of about 1% per year. The de-crease is greatest for long-distancemigrants, and it heralds profoundchanges in the Central European avi-fauna.Populations of large birds such as ea-gles and storks can be determined ac-curately, and most of the Europeanbreeding pairs are monitored. Forspecies that are more common or areharder to observe, such as crows andowls, only rough estimates are possi-ble [3]. Serious problems are encoun-tered in songbirds. Abundant, widelydistributed, and unobtrusive speciescannot be counted completely or di-rectly; regional estimates must bebased on indirect procedures such asrecording territorial song. Such esti-mates are often biased by varying,nonquantifiable “observer quality”[5]. Therefore only a few countrieshave established sufficiently reliableprograms for monitoring songbirdsduring the breeding period [6, 7].In 1968 we began testing standardizedtrapping procedures for monitoringsongbird populations in order to re-duce differences among observers bya more objective method. The resultswere positive [8], and in 1972 wetherefore initiated the “Mettnau-Reit-Illmitz” program (based onthree stations, Mettnau in southernGermany, Reit in northern Germany,and Illmitz in Austria. This programwas later extended, and temporarilygrew into an ESF network encom-passing Europe and Africa [9]). TheMettnau station has operated sincethe outset, and we report here on theresults of a full quarter of a century ofsongbird population monitoring.The samples are obtained by trappingpassage migrants during the autumnmigration while staging at rest sites.A suitable study area must (a) becharacterized by largely unchangingvegetation, (b) include different habi-tats so that birds with different eco-logical requirements can rest there,and (c) be a protected area of guaran-teed long-term existence. The Mett-nau peninsula, with a 50-year-old birdsanctuary, is ideal for the purpose[10]. The 35 songbird species selectedfor monitoring include regularly stag-ing long-, intermediate-, and short-distance migrants (Table 1).The birds are trapped in nylon netsnormally used to catch birds for ring-ing; 2 m high and 7 m long, they areset up between wooden bars on poles.A wall is formed by 52 nets extendingthrough 8 different habitats (from abrush zone through forested and wetregions). The annual trapping periodis June 30–November 6 and includesthe entire autumn migratory periodof songbirds in Central Europe. Thenets are checked hourly from dawnuntil soon after dusk; trapped birdsare ringed (to prevent double count-ing), subjected to biometric tests andthen released. The monitoring condi-tions (annual setting up of the nets,collecting the birds, data collection,etc.) are standardized as far as possi-ble [10]. Most of the investigatedbirds come from Central Europe, al-though some have traveled fromnorthern, eastern, and western Eu-rope, and a small proportion are localbreeding birds. These origins areknown from recoveries of ringed indi-viduals [11] and from biometric dataon population differentiation [10].Test studies have confirmed thatstandardized trapping procedures ef-fectively give reliable estimates ofsongbird populations. Safriel andLavee (1991) showed that the numberof palaearctic songbird migrants trap-ped in Sinai is correlated positivelywith estimates of their European pre-migratory population sizes [12]. Dunnet al. (1997) demonstrated that trendsin the annual capture indices of song-birds trapped during autumn migra-tion in Michigan are correlated posi-tively with trends in breeding birdsurvey data from their breedinggrounds and conclude that “intensivestandardized netting can be a usefulpopulation monitoring tool” [13]. Wehave consistently found that trends intrapping data reliably reflect thosefrom other sources such as single-spe-cies population studies and country-wide population estimates for RedLists, etc. [4]. Thus data from 147,661individuals that were caught at Mett-nau between 1972 and 1996 reflectthe population development of 35Central European songbird species,as follows.

90 citations


Journal ArticleDOI
TL;DR: Understanding the social interactions among individuals of the wild ancestor of the domesticated form requires knowledge of how their behavior patterns were brought about by natural selection during the process of social evolution.
Abstract: Among mammals a majority of each individual's daily expectations, motivations, and behaviors are directed to encounters with conspecifics. Therefore the knowledge of the genesis, control, and consequences of social interactions is crucial for understanding their social life. We present here our research on the sociophysiology, domestication, and social evolution of wild (Cavia aperea and Galea musteloides) and domestic (Cavia aperea f. porcellus) guinea pigs, which summarizes general rules for many group-living mammals. It is shown that social interactions have consequences not only for the individuals' reproductive success but also for their degrees of stress and welfare. The way in which individuals interact is controlled not only by the present environment but also by the previous social experiences which they have gathered during their behavioral development. Furthermore, the study of ontogeny does not begin at birth, because prenatal social factors acting on pregnant females can also affect the way in which the offspring will interact when adult. In addition, to understand the genesis of interactions between domesticated animals implies knowledge of the behavioral and physiological changes which occurred during the process of domestication. Finally, understanding the social interactions among individuals of the wild ancestor of the domesticated form requires knowledge of how their behavior patterns were brought about by natural selection during the process of social evolution.

89 citations


Journal ArticleDOI
TL;DR: The total number and sex of dragonflies trapped by the crude-oiland water-filled trays during the first choice experiment and the relative brightness, degree of polarization and direction of polarization of light reflected from the trays are shown.
Abstract: Table 1. Row 1: The total number and sex (F: female, M: male) of dragonflies (Sympetrum vulgatum, Ischnura pumilio, Enallagma cyathigerum) trapped by the crude-oiland water-filled trays during the first choice experiment. Rows 2–4: The relative brightness, degree of polarization and direction of polarization of light reflected from the trays and measured by video polarimetry in the blue spectral range (lp470 nm) from a direction of view of 707 with respect to the vertical. The trays are designated by S1 and S2 as in Fig. 2

87 citations


Journal ArticleDOI
TL;DR: New data are presented that clearly show that the mating system of P. vulgaris is not simply a resource-defense polygyny, as has previously been thought, and four main predictions of the indicator model of the theory of sexual selection of Panorpa vulgaris are confirmed.
Abstract: has become a model insect for testing theories of sexual selection. This contribution summarizes that which has been learned in recent years and presents new data that clearly show that the mating system of P. vulgaris is not simply a resource-defense polygyny, as has previously been thought. In P. vulgaris neither the pattern in food exploitation nor the ratio of variance in the lifetime reproductive success of the two sexes is in accordance with that expected in resource defense polygynous mating systems. Lifetime mating duration is the most important proximate determinant of male fitness. Males employing alternative mating tactics obtain copulations of varying duration in relation to the following sequence: saliva secretion 1 food offering 1 no gift. The number of salivary masses which males provide to females during their lifetime is significantly correlated with the lifetime condition index. The condition index depends on the fighting prowess of males and their ability to find food items. Thus saliva secretion of Panorpa is considered a Zahavian handicap, which can serve as an honest quality indicator used by mating females. Our results confirm four main predictions of the indicator model of the theory of sexual selection: (a) the indicator signals high ecological quality of its bearer, (b) the indicator value increases with phenotypic quality, (c) the indicator value is positively correlated with the genetic quality affecting offspring fitness in a natural selection context, and (d) the quality indicator is more costly for low- than for high-quality individuals. The evolutionary consequences of the mating pattern and the sperm competition mechanism in P. vulgaris are discussed in the context the way in which sexual selection creates and maintains sperm mixing and the evolution of a promiscuous mating system.

84 citations


Journal ArticleDOI
TL;DR: These recent results establish a multifaceted regulatory role for PTS in addition to its well-established function in active sugar uptake in gram-positive bacteria.
Abstract: and thereby the activity of the catabolite activator protein. In many gram-positive bacteria catabolite repression is mediated by the catabolite control protein CcpA, which requires HPr Ser-46 phosphate as a cofactor to regulate transcription of catabolic genes. HPr Ser-46 phosphate is produced by HPr kinase, the activity of which is under metabolic control via the concentrations of glycolytic intermediates. These recent results establish a multifaceted regulatory role for PTS in addition to its well-established function in active sugar uptake.

Journal ArticleDOI
TL;DR: Horvath G, Zeil J, Wehner R, Varju D, North JA, Duggin MJ (1997) Stokes vector imaging of the polarized sky-dome and its relevance for water detection by aquatic insects as discussed by the authors.
Abstract: 339 5. Neuberger H (1950) Arago’s neutral point: a neglected tool in meteorological research. Bull Am Met Soc 31 :119–125 6. Van de Hulst HC (1952) Scattering in atmospheres. In: Kniper GP (ed) The atmosphere of the earth and planets. University of Chicago Press, Chicago 7. Sekera Z (1957) Light scattering in the atmosphere and the polarization of skylight. J Opt Soc Am 47 :484–490 8. Holzworth GC, Rao CR (1965) Studies of skylight polarization. J Opt Soc Am 55:403–408 9. Konnen GP (1985) Polarized light in nature. Cambridge University Press, Cambridge 10. Bellver C (1987) Influence of particulate pollution on the positions of neutral points in the sky at Seville (Spain). Atmospheric Environment 21 :699–702 11. Coulson KL (1988) Polarization and intensity of light in the atmosphere. Deepak, Hampton 12. Walraven RL (1981) Polarization imagery. Opt Eng 20 :14–18 13. Wehner R (1976) Polarized-light navigation by insects. Sci Am 235(1) :106–114 14. Wehner R (1997) The ant’s celestial compass system: spectral and polarization channels. In: Lehrer M (ed) Orientation and communication in arthropods. Birkhauser, Basel, pp 145–185 15. Coulson KL, Whitehead VS, Campbell C (1986) Polarized views of the earth from orbital altitude. Proc SPIE 637, Ocean Optics VIII:35–41 16. North JA, Duggin MJ (1997) Stokes vector imaging of the polarized sky-dome. Appl Opt 36 :723–730 17. Prosch T, Hennings D, Raschke E (1983) Video polarimetry: a new imaging technique in atmospheric science. Appl Opt 22 :1360–1363 18. Egan WG (1986) Proposed design of an imaging spectropolarimeter/photometer for remote sensing of earth resources. Opt Eng 25 :1155–1159 19. Wolff LB (1993) Polarization camera technology. Proc DARPA Image Understanding Works, pp 1031–1036 20. Deschamps PY, Breon FM, Leroy M, Podaire A, Bricaud A, Buriez J C, Seze G (1994) The Polder mission: instrument characteristics and scientific objectives. IEEE Trans Geosci Rem Sens 32 :598–615 21. Cronin TW, Shashar N, Wolff LB (1994) Portable imaging polarimeters. Proc 12th IAPR Int Conf Pattern Recogn, pp 606–609 22. Shashar N, Cronin TW, Johnson G, Wolff LB (1995) Portable imaging polarized light analyzer. SPIE Proc series 2426 :28–35 23. Horvath G, Zeil J (1996) Kuwait oil lakes as insect traps. Nature 379 :303–304 24. Horvath G, Varju D (1997) Polarization pattern of freshwater habitats recorded by video polarimetry in red, green and blue spectral ranges and its relevance for water detection by aquatic insects. J Exp Biol 200 :1155–1163 25. Horvath G, Gal J, Wehner R (1997) Why are water-seeking insects not attracted by mirages? The polarization pattern of mirages. Naturwissenschaften 84 :300–303

Journal ArticleDOI
TL;DR: The principle of adaptive growth which biological structures use to minimize stress concentrations has been incorporated into a computer-aided optimization (CAO) procedure that optimizes the performance of fiber-composite materials by aligning the fiber distribution with the force flow, again mimicking the structure of trees.
Abstract: Optimization methods are presented for engineering design based on the axiom of uniform stress. The principle of adaptive growth which biological structures use to minimize stress concentrations has been incorporated into a computer-aided optimization (CAO) procedure. Computer-aided optimization offers the advantage of three-dimensional optimization for the purpose of designing more fatigue-resistant components without mathematical sophistication. Another method, called computer-aided internal optimization (CAIO), optimizes the performance of fiber-composite materials by aligning the fiber distribution with the force flow, again mimicking the structure of trees. The lines of force flow, so-called principal stress trajectories, are not subject to shear stresses. Avoiding shear stresses in the technical components can lead to an increase in maximum load capacity. By the use of a new testing device strength distributions in trees can be determined and explained based on a new mechanical wood model.


Journal ArticleDOI
TL;DR: The initial results of a study testing the light-dependent mechanisms of magnetoreception in birds in young homing pigeons suggest that during a transient phase in the early development of the navigational system young birds depend entirely on their magnetic compass for homeward orientation.
Abstract: Thirty years ago magnetic compass orientation was first demonstrated in the European robin, a migratory bird [1, 2]. Other bird species and numerous other animals have since been shown to use the magnetic field as a compass (for summary see [3]). However, the mechanisms by which the magnetic field is perceived are still largely unclear. One hypothesis currently under discussion proposes light-dependent primary processes based on excited states of macromolecules, probably photopigments [4–7]. Since such processes may depend on the energy, and thus on the wavelength, of light, the orientation of birds under various wavelengths of light is of crucial interest. Here we report the initial results of a study testing the hypothesis in young homing pigeons, exposing the birds to monochromatic red and green light during displacement. When Leask [4, 5] first proposed light-dependent mechanisms of magnetoreception in birds he suggested using various light regimes to test the wavelength dependency of magnetic orientation. Such wavelength dependency was first described in Salamanders [8]. Experiments with passerine migrants also showed that orientation in the absence of celestial cues is affected by the wavelength of light. The birds were well oriented under 433 nm blue and 565 nm green light but failed to show oriented behavior under 630 nm red light , although they were as active as under white light [9–11]. These findings are in agreement with light-dependent processes as they seem to indicate that long-wavelength lacks sufficient energy to start the processes required for magnetoreception. These experiments all used the same behavior to test for magnetic orientation, namely the directional tendencies of captive migrants during migration. It thus seemed desirable to test birds in a different behavioral context in which they also use the magnetic field as a compass. One such behavior is the home orientation of very young, inexperienced pigeons after displacement. Experienced birds preferably use their navigational “map” to determine the homeward course by site-specific information. However, before the “map” is available – it is established by experience during the birds’ first months of life (for summary see [12, 13]) – young birds rely on directional information collected en route during the outward journey. When transported in an altered magnetic field, they were disoriented, whereas the same field applied at the release site had no disorienting effect. This suggests that the very young birds obtain their home course by recording the net direction of the outward journey with their magnetic compass [14, 15]. Thus during a transient phase in the early development of the navigational system young birds depend entirely on their magnetic compass for homeward orientation. As a consequence any interference with magnetoreception during displacement should result in disoriented behavior. For the first tests we selected the release site Gernsheim, 42.0 km south of the loft at Frankfurt (50 808'N, 8840'E), with the home direction 16 8. For this site a marked release site bias [16] is typical. Frankfurt pigeons regularly show large deviations to the west, with mean directions mostly between 2778 and 3598 (median: 3138) [17, 18]. Young pigeons several months old and already with a “map” but without any training experience showed an extreme deviation with a mean at 251 8SW. Apparently the local


Journal ArticleDOI
TL;DR: A communal hymenopteran species, Lasioglossum(Chilalictus)hemichalceum, is examined to determine why group members engaged in demonstrably risky activities (foraging) tolerate the selfish behavior (remaining in the nest) of unrelated nestmates.
Abstract: Recent studies provide a new challenge to the adequacy of theories concerning the evolution of cooperation among nonrelatives: some individuals perform high-risk activities while others do not. We examined a communal hymenopteran species, Lasioglossum (Chilalictus) hemichalceum, to determine why group members engaged in demonstrably risky activities (foraging) tolerate the selfish behavior (remaining in the nest) of unrelated nestmates. Experimental removal of adult females indicated that their presence is required for the protection of brood from ant predators. Nonforagers ensure the continued presence of adults in the nest if the risk-taking foragers die, thereby safeguarding the survival of forager offspring. This results in an unequal distribution of risky activities within social groups in which avoidance of risky activities by some group members is ultimately beneficial to risk takers.


Journal ArticleDOI
Zander Cd1
TL;DR: Analyses of parasite communities, especially those of small fish hosts, reveal characteristics which differ from communities in the marine milieu: suspension of specificity, reduction in the number of hosts in life cycles, and adaptation to genuine brackish water hosts.
Abstract: The Baltic Sea is one of the greatest brackish waters, and for 7000 years it has been affected by the influx of haline waters from the North Sea Many marine and some fresh water organisms have adapted to its lower salinity Some organisms, referred to as genuine brackish water species, predominate over their near relatives in this environment All these elements are also present among parasites, which differ in the degree of specialization to their hosts Analyses of parasite communities, especially those of small fish hosts, reveal characteristics which differ from communities in the marine milieu: (a) suspension of specificity, (b) new hosts, (c) reduction in the number of hosts in life cycles, and (d) adaptation to genuine brackish water hosts The view of the Baltic Sea as a species-poor but balanced ecosystem is also valid for parasites The Baltic Sea is endangered by the high level of eutrophication, as the organisms are not adapted to its consequences The study of parasite communities reveals such threatening conditions for the respective environments

Journal ArticleDOI
TL;DR: This poster presents a probabilistic reconstruction of the distribution and distribution of Carboniferous strata of the Tournaisian to Westphalian age, using a model derived from X-ray diffraction analysis of 120-million-year-old remains found in Argentina.
Abstract: L.D. Martin, Z. ZhouNatural History Museum and Department of Systematics and Ecology,University of Kansas, Lawrence, KS 66045, USAL. HouInstitute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences, P.O. Box 643, Beijing 100044, ChinaA. FeducciaDepartment of Biology, University of North Carolina, Chapel Hill,NC 27599-3280, USA


Journal ArticleDOI
TL;DR: In this paper, the 13 C isotope composition of plant-derived soil n-alkanes in a soil sample from an experimental field cropped 23 years with maize to label soil organic carbon was analyzed.
Abstract: Soil organic matter is a very complex mixture of compounds derived from the decay of numerous living organisms. Earlier reports suggest that soil organic molecules may occur unaltered in a "bound" form, e.g. by encapsulation in the humic substances matrix or by binding involving weak forces such as H bonds and Van der Waals forces. This issue is relevant to the release of pesticides and other toxic compounds in waters during several years, which suggests a particular mechanim of storage of organic compounds in soil organic matter. However, so far, the mechanim of weak binding is poorly known due to possible analytical bias in the isolation of "weakly-bound" molecules, and to the lack of analytical approaches that can distinguish a "free" compound from its "weakly-bound" counterpart. Here, we analysed the 13 C isotope composition of plant-derived soil n-alkanes in a soil sample from an experimental field cropped 23 years with maize to label soil organic carbon. Indeed, cultivating maize, a C 4 plant with 13 C-enriched carbon, on a soil previously cropped with C 3 plants, introduces 13 C-enriched carbon in the soil. Thus maize-derived soil carbon can be distinguished from previously-cropped plant soil carbon by 13 C analysis. We used a recently developped analytical technique, gas chromatography - isotope ratio monitoring mass spectrometry (GC-IRMS), that allows to measure the 13 C isotope ratio of individual substances occurring in complex mixtures. We analysed three pools of C 27 -C 33 n-alkanes in the same soil sample: 1) "free" n-alkanes that were extracted with CHCl 3 -MeOH, 2) "bound" n-alkanes that were extracted from humin, the macromolecular part of soil organic matter, and 3) "bound" n-alkanes that were released by pyrolysis of the pre-extracted humin. Our results show that free n-alkanes are 13 C-enriched by +5.8-7.0‰ versus their bound n-alkanes counterparts. This finding have several implications. First, this clear isotope difference of the the same substance occurring either in free or bound form proves that there is no analytical bias such as a lack of exhautive extraction. Second, the higher 13 C content of free n-alkanes evidences their higher turnover versus bound n-alkanes. Here a first-order kinetic law yields an age difference of 7 years between free and bound n-alkanes. Third, since n-alkanes are apolar compounds our results demonstrate the existence of a mechanism of weak binding involving either encapsulation or weak forces. This mechanism could explain why chemicals such as pesticides are well preserved in soil then released in waters several years after the end of their use in cropping systems. It is also relevant to the storage of organic-N compounds as possible plant nutrient precursors.


Journal ArticleDOI
TL;DR: The orb-web is an energetic and behavioural estimator of a spider’s dynamic foraging and reproductive strategies and its role in prey consumption behaviour is investigated.
Abstract: Naturwissenschaften 85 (1998) Q Springer-Verlag 1998 Sébrier M A, Krafft B (1993) Influence of prior experience on prey consumption behaviour in the spider Zygiella x-notata. Ethol Ecol Evol 5 :541–547 Sherman PM (1994) The orb-web: an energetic and behavioural estimator of a spider’s dynamic foraging and reproductive strategies. Anim Behav 48 :19–34 Vollrath F, Downes M, Krackow S (1997) Design variability in web geometry of an orb-weaving spider. Physiol Behav 62 :735–743 Vollrath F, Samu F (1997) The effect of starvation on web geometry in an orb-weaving spider. Bull Br Arachnol Soc 10 :295–298 Weissmann M, Vollrath F (1998) The effect of leg loss on a web spider’s prey catching behaviour. Bull Br Arachnol Soc (in press) Witt PN, Reed CF, Peakall DB (1968) A spider’s web: problems in regulatory biology. Springer, Berlin Heidelberg New York

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TL;DR: The wide diversity of intracellular bacteria in protozoa has become particularly obvious since they have begun to be classified by molecular techniques.
Abstract: Intracellular bacteria in humans are typically detrimental, and such infections are regarded by the patients as accidental and abnormal. In protozoa it seems obvious that many bacteria have coevolved with their hosts and are well adapted to the intracellular way of life. Manifold interactions between hosts and intracellular bacteria are found, and examples of antibacterial resistance of unknown mechanisms are observed. The wide diversity of intracellular bacteria in protozoa has become particularly obvious since they have begun to be classified by molecular techniques. Some of the bacteria are closely related to pathogens; others are responsible for the production of toxins.

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TL;DR: A molecular picture of the structural elements important for the activity of voltage-gated ion channels has been established, which has assisted in clarifying the molecular basis of the electrical excitability of cells.
Abstract: Voltage-gated ion channels are key molecules for the generation of electrical signals in cells. They are integral membrane proteins which are activated by a depolarized membrane potential resulting in a conformational change, allowing ions to permeate. Voltage-gated ion channels can either be inactivated from this open state by an additional conformational change which leads to a nonconducting state of the channel, or they may be deactivated by a repolarized membrane potential. Following the first successful cloning of voltage-gated ion channels in 1984 the combination of molecular biological and electrophysiological techniques has been very fruitful in the investigation of the structure and function of these membrane proteins. From these studies a molecular picture of the structural elements important for the activity of voltage-gated ion channels has been established. This has assisted in clarifying the molecular basis of the electrical excitability of cells.

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TL;DR: Global change, i.e. the mega-process radically transforming the relationship between nature and human civilization since the end of World War II, is investigated and evidence is provided that geocybernetics is actually feasible on the basis of earth system modelling and fuzzy-control techniques.
Abstract: Global change, i.e. the mega-process radically transforming the relationship between nature and human civilization since the end of World War II, is investigated from the point of view of systems analysis. It is argued that this unbridled process should rather be domesticated by planetary control strategies transpiring from a new science called “geocybernetics”. The formal aspects of geocybernetic theory are sketched and illustrated in a tutorial theatre world reflecting the overall environment and development problematic. Within this setting a straightforward operationalization of the sweeping “sustainable development” ideal through a set of concise paradigms can be achieved. Evidence is provided that geocybernetics is actually feasible on the basis of earth system modelling and fuzzy-control techniques.

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TL;DR: The responses of lepidopteran auditory receptors to intraspecific acoustic courtship signals are shown, showing that sound emission in males (in all the successful matings observed) and in females (in some cases) is indeed present during its courtship.
Abstract: Correspondence to: M.V. Sanderford Field and laboratory observations of the mating behavior ofEmpyreuma affinis show that ultrasonic signals consistently produced by the males and occasionally by the females are a distinctive feature of the courtship of this insect. The sounds produced by males and females show a significant sexual dimorphism, most dramatically in their modulation cycle rates. Moreover, males produce two distinct types of emissions that differ in modulation cycle rate. Electrophysiological recordings of spike activity at the tympanic nerve of males and females were carried out, and the responses to prerecorded intraspecific acoustic signals emitted during courtship behavior are shown. The results predict that the main informational content of these signals is in the modulation cycle rate, which is followed faithfully by the receptor cells. In 1864 Laboulbene suggested that acoustic signals play a role in the reproductive behavior of the Arctiidae [1]. Peter [2] later described the use of sound by a day-flying Alpine arctiid moth in its mating behavior, and more recently ultrasonic emissions associated with reproductive behavior have been described for an additional three arctiid species [3, 4]. The first ctenuchine moth to be implicated in acoustic mating behavior was Empyreuma affinis (E. pugione, in earlier references), the “scarlet-winged wasp moth,” a day-flying moth endemic to the Caribbean [5–7]. Since the initial (1983) publication on the ears and sound emission organs of E. affinis [8, 9] additional information has been gathered revealing characteristics which appear to adapt it for acoustic intraspecific communication: (a) Males and females produce sounds with striated and partially denuded tymbals which resemble those of other acoustically active arctiids [10]. (b) The acoustic signals of E. affinis consist of ultrasonic clicks composed of frequencies from 14 to 64 kHz with a major peak at 34 kHz [11] with signal sound pressure levels approaching 80 dB at 2 cm [10]. (c) Audiograms of the A1 and A2 receptor cells of males and females show a close frequency match of auditory sensitivity with the power spectrum of the sound emitted, and an overlap of the Q10 dB bandwidth of sound reception and emission [11]. (d) The auditory organ of this species can detect directional information over an intensity range of at least 60 dB [11]. Also behavioral studies [12] have shown that the time spent in courtship behavior and mating was significantly reduced when either the male or female was deafened. These data suggest that E. affinis engages in acoustic courtship communication, and that both sexes emit acoustic signals during courtship [13]. Our results confirm that sound emission in males (in all the successful matings observed) and in females (in some cases) is indeed present during its courtship. Audition in moths has been often studied in the context of bat/moth interactions [14–17]. Acoustic stimuli resembling bat echolocation signals, and in a few cases natural bat cries have been used to stimulate the tympanic organs [18–21] or central auditory neurons of moths [22]. The use of conspecific moth sounds to evoke tympanal responses has been limited [18, 23, 24]. We here show the responses of lepidopteran auditory receptors to intraspecific acoustic courtship signals.

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TL;DR: In this paper, the authors used a "biomarker" approach, developped mainly in sedimentary geochemistry, to gain some insight on the mechanims of preservation of soil organic matter.
Abstract: Soil organic matter is a very complex mixture of compounds derived from the decay of living organisms such as plants, fungi and bacteria. The mechanisms that control the preservation of soil organic matter are poorly known. This is notably due to our scarce knowledge of the molecular structure of humin, the insoluble part of soil organic matter. Three major hypotheses have been proposed to explain the formation of soil organic matter: the plant alteration hypothesis, the microbial synthesis hypothesis and the chemical polymerisation hypothesis. Here we used a "biomarker" approach, developped mainly in sedimentary geochemistry, to gain some insight on the mechanims of preservation of soil organic matter. We analysed the compounds occurring in soil humin. We isolated humin from a maize crop soil by solvent extraction to remove free lipids, then by NaOH extraction to remove humic and fulvic acids, then by HF/HCl treatment to remove minerals. The humin residue was then pyrolysed at 600°C. The pyrolysate was fractionated into alkane/alkene and aromatic fractions by silica gel column chromatography. The fractions were analysed by gas chromatography coupled to mass spectrometry (GC-MS). We identified n-alkanes, n-alkenes, prist-1-ene, sterenes, hopenes and aromatic steroids in the humin pyrolysate. The results show that the stabilisation of soil humic substances may be achieved by selective preservation of lipids, involving three processes: encapsulation of small apolar molecules, chemical bonding of functionalized biomarkers, and preservation of straight-chain microbial polymers.

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TL;DR: Originating from cellulose manufacturing and from paper mills, large amounts of poisonous chlorinated compounds contaminated the coastal waters of Sweden and Finland until the 1980s, which caused eutrophication and consequent oxygen depletion in coastal bottom waters.
Abstract: The Baltic Sea is almost totally surrounded by land and therefore more endangered by pollution than other marine areas. The sources of marine pollution are municipal and industrial waste inputs directly into the sea or via rivers, and atmospheric inputs mainly from traffic and agriculture. The increase of inorganic plant nutrients (NH3, NOx, PO4) caused eutrophication and consequent oxygen depletion in coastal bottom waters as well as in the depths of the open sea. In the anoxic sediments, hydrogen sulfide can be produced by protein-decomposing and sulfate-reducing bacteria. The bottom fauna will be destroyed and only H2S tolerant microorganisms can survive. Originating from cellulose manufacturing and from paper mills, large amounts of poisonous chlorinated compounds contaminated the coastal waters of Sweden and Finland until the 1980s. Most of this material is still present in sediments of the central Baltic Sea and can be resuspended by near bottom currents. To reduce pollution and improve the situation in the Baltic Sea, the surrounding countries organized the Helsinki Convention, which came into force on 3.5.1980. The Helsinki Commission (HELCOM) founded in 1974 acts as coordinator and is responsible for the enforcement of the Baltic monitoring program and international research projects. The activities of HELCOM have led to the reduction of dangerous pollutants which in turn has caused the regeneration of flora and fauna in some areas. Further improvements can be expected.