Showing papers in "Naturwissenschaften in 1992"

Abiotic synthesis of amino acids under hydrothermal conditions and the origin of life: a perpetual phenomenon?

Abstract: Today, subaqueous hydrothermal activity is a very dynamic process. For example, the entire volume of water in the ocean is circulated in approximately 10 million years through the more than 70000 km length of global ridge systems scarring the bottom of the Earth's oceans [1]. Hydrothermal circulation also takes place off-ridges in the oceanic crust and the covering sediments [2, 3]. Early in the Earth's history (4 × 10 9 years ago or so) hydrothermal activity was even more intensive, mostly because of the lack of thick continental masses and higher heat fluxes cooling the planet. As soon as water was able to condense at the surface of the Earth, all processes associated with subaqueous hydrothermal activity began, and probably continued uninterrupted until the present. The physical and chemical conditions within submarine hydrothermal systems can vary greatly. Aqueous hydrothermal fluid temperature can range from cold (temperature of bottom seawater) in the recharge areas, to hot (e.g., 650-700°C, closest approach of aqueous fluid to magma [2]) closer to magmatic heat sources, deeper in the Earth's crust. Redox conditions (E h, which are of extreme importance in determining the direction of chemical reactions and the stability of chemical species, also vary, from relatively oxidizing in the hotter zones to more reducing in the colder zones of the system. For the redox couple CO2/CH4, the conditions are oxidizing (stability field of CO2) at higher temperatures (above 300 or 400 °C), and reducing (stability field of CH4) at lower temperatures in a typical oceanic crust environment [4]. Many other parameters show variations, for example, mineral assemblages, chemical species activities, and pH, to name only a few [2]. Hydrothermal conditions are ubiquitous in the Earth's crust. Direct, observable expression of hydrothermal activity at the seafloor is in the form of hot aqueous fluids (at temperatures of up to 400°C or more) emanating directly from vents or seeps [5, 6]. However, hydrothermal fluids at the temperature conditions measured in vents and seeps represent only a very small portion of the entire mass of aqueous fluid perpetually circulating in the oceanic crust. An estimated 96 °7o of the mass of hydrothermal water circulating in the oceanic crust is at a temperature of around 150°C [3, 7, 8]. The E h of aqueous fluids circulating in the hydrothermally altered oceanic crust is reducing, and is generally controlled by the mineral assemblage pyrite/pyrrhotite/magnetite [9, 10]. The pH is close to neutral around 150°C, becoming more acidic as temperature increases towards 250°C, and then less acidic again at higher temperatures [t 1]. Chemical reactions take place in response to changes in chemical and physical conditions. For example, at 150°C, dissolved CO 2 introduced in a system consisting of an aqueous phase in contact with the pyrite/pyrrhotite/ magnetite mineral assemblage should be reduced to C H 4 as the system responds to reach equilibrium [4]. However, stable chemical equilibrium be-

Mechanisms of electromagnetic interaction with cellular systems.

Abstract: The question of how electromagnetic fields - static or low to high frequency - interact with biological systems is of great interest. The current discussion among biologists, chemists, and physicists emphasizes aspects of experimental verification and of defining microscopic and macroscopic mechanisms. Both aspects are reviewed here. We emphasize that in certain situationsnonthermal interactions of electromagnetic fields occur with cellular systems.

Entwurf einer neurologischen Theorie der Sprache

Abstract: Recently, theories of neuronal computation in the brain have become detailed enough, so that it becomes possible to speculate about mechanisms underlying the production and perception of language. How many neurons are involved when we utter, or understand, a word, a phoneme, a phrase? In what neuronal form are the rules of grammar laid down in the synaptic network? To what does a morpheme correspond in the brain?

Generation of a vortex chain in the wake of a Suhundulatory swimmer

Abstract: For a fish swimming at constant speed thrust must be sufficient to overcome drag. Drag of an undulating fish can differ considerably from drag observed for a rigid body and cannot be measured directly. Thrust can be calculated by applying hydrodynamic models, such as slender body theory [1], to observed kinematic patterns. Due to simplifying assumptions, shortcomings in the various applications, and probably behavioral variability, the estimated thrust coefficients (CT) range from ca. 0.5 c D to ca. 5 CD [2, 3] for animals swimming at the same Reynolds numer (c D: drag coefficient). • We present an estimate of thrust and efficiency based for the first time on the flow in the wake of freely swimming rainbow trout (Oncorhynchus mykiss Waldbaum; cf. [4, 5]). This calculation required the reconstruction of the three-dimensional vortex pattern as well as a quantification of the flow velocities, both of which are missing in studies so far available [6, 7]. We

Ultrasound-sensitive ears in a parasitoid fly

Abstract: Hearing organs have been evolved in many different insect orders, where they are used mostly in intraspecific acoustic communicat ion or predator defense [ 1 3]. Except for some nearfield receptors (particle-displacement detectors) sensitive to low-frequency sound, they are usually built as tympanic organs with large membranes that react to sound-pressure changes [3]. Dipterans are known to perceive conspecific songs in the near field with the antenna [3]. Tympanal organs, however, have never been described for flies (order Diptera), al though several studies [ 4 7 ] have documented the attraction of fly parasitoids to the songs of their hosts. Here, we present results from a field study on a tachinid fly that hunts acoustically for ul t rasoundproducing bushcrickets, and describe a novel tympanal organ. The tachinid fly Therobia leonidei Mesnil (1964), which is found throughout southern Europe [8], was studied in Greece for several years during May and June. Here, it was observed as a parasi toid of the bushcricket species Poecilimon veluchianus Ramme (1930) and its closest relatives (P. thessalicus, P. propinquus, P. mariannae). The fly parasitizes only male bushcrickets which can produce a calling song. Surgically muted males were never infested (Table 1). The bushcrickets which call only at night were probably at tacked at that t ime since Th. leonidei is also noc turna l ly active [8]. The infection rates of male bushcrickets of adjacent populat ions vary from zero to 80 % even over distances of only some 100 m. In southern France other bushcricket species have also been found to be hosts, the infect ion again being restricted almost exclusively to males [9]. The fly larvae feed within the bushcrickets and caged parasitized animals die about 6 1 0 days after infection. The fly maggots emerge from their host and pupate within a few hours. Adul t flies appear 2 to 3 weeks later. The results indicate the presence of a sound-detecting organ in the fly. A visual orientation is unlikely because of the nocturnal singing period of the bushcrickets. Both sexes of the adult fly possess a pc-

Risk shift between males and females in the pair-forming behavior of bushcrickets

Abstract: Entomol. 13, 393 (1988) 9. Sugihara, G., May, R. M. : Trends Ecol. Evol. 5, 79 (1990) 10. Batschelet, E. : Circular Statistics in Biology. London: Academic Press 1981 11. Bovet, P., Dejean, A., Granjon, M.: Ins. Soc. 36, 51 (1989) 12. Fourcassi6, V., Traniello, J. F. A.: in preparation 13. Traniello, J. F. A., in: Interindividual Behavioral Variability in Social Insects, p. 91 (ed. Jeanne, R. L.). Boulder, Col. : Westview Press 1988 14. Bovet, P., Benhamou, S.\" Anim. Behav. 42, 57 (1991) 15. Jander, R.: Ann. Rev. Ecol. Syst. 6, 171 (1975) 16. Wehner, R., Srinivasan, M. V.: J. Comp. Physiol. 142, 315 (1981) 17. Hoffmann, G., in: Biological motion. Lecture Notes in Biomathematics, p. 305 (eds. Alt, W., Hoffmann, G.). Berlin-Heidelberg-New York: Springer 1990

First identification of drugs in Egyptian mummies.

Abstract: Im zitierten Beitrag behaupten die Autoren, in Haaren und Geweben von Mumien (1070 v. Chr. 395 n. Chr.) Kokain, Haschisch und Nikotin nachgewiesen zu haben. Der Gebrauch yon Haschisch wird schon yon Herodot (490--425 v. Chr.) erwfihnt. Kokain hingegen wird aus den Bl~ittern des Kokastrauchs Erythroxylon coca gewonnen, der im Andengebiet w~chst und erst nach 1500 in Europa bekannt wurde. Es ist also praktisch ausgeschlossen, dab die Agypter Kokain eingenommen haben k6nnen. Nikotin stammt aus der ursprfinglich in Mexiko (Gebiet um Tabasco) beheimateten Pflanze Nicotiana tabacum, deren Bltitter erstmals ebenfalls nach 1500 nach Europa kamen. In Amerika scheint der Gebrauch des Tabaks sich um 600 unserer Zeitrechnung ausgebreitet zu haben. Inwieweit andere Solanaceen Nikotin enthalten, ist mir nicht bekannt, es ist dies nicht auszuschliegen. Aber der Gebrauch im alten Agypten erscheint auch ~uf3erst unwahrscheinlich. FiJr die in den Naturwissenschaften publizierten Befunde gibt es mehrere Erkl~irungsm6glichkeit en: 1) Die Autoren haben keine grof3e Erfahrung in der Anatytik und haben fehlerhafte Befunde publiziert. Wenn sie sich mit solchen Problemen besch~iftigen, h~itten sie sich auch informieren k6nnen, ob diese Stoffe i iberhaupt zur Verftigung standen, wobei dieses Wissen heute eigentlich zur Allgemeinbildung geh6rt. Dies gilt

Chirality and field activity of rhynchophorol, the aggregation pheromone of the American palm weevil

Abstract: The American palm weevil, Rhynchophoruspalmarum (L.) (Coleoptera: Curculionidae), is the major vector of Rhadinaphelenchus cocophilus, a nematode which causes red ring disease in oil and coconut palms throughout Central and South America [1]. Losses to this disease are significant, and its incidence has been correlated with weevil population density [1]. Trapping with insecticide-treated pieces of palm is practiced but traps lose their attractancy after a few days [2]. Therefore, the availability of a stable semiochemical to enhance trap attractancy would be of significant value in control of this pest. Recently, Rochat et al. [3] reported the identification and laboratory activity of a male-produced aggregation pheromone, 6-methyl-2(E)-hepten-4-ol (1) for this weevil. Weevils were collected on sawn sections of oil palm trunk in the Palma Tica plantations at Quepos and Coto 47, Costa Rica. They were maintained in laboratory cultures on fresh sugarcane or apples. Volatiles were collected by drawing air over 20 25 male or female R. palmarum in a Nalgene desiccator fitted with a charcoal filter at the inlet and a Porapak Q trap at the outlet. Aerations were carried out for 2 4 days at a flow rate of 85 1/h [4]. Trapped volatiles were extracted from the Porapak Q with pentane which was concentrated by distillation [4]. Gas chromatographic analysis conducted

Transient increase in membrane permeability of L1210 cells upon exposure to lithotripter shock waves in vitro.

Abstract: Over the last few years, various approaches to assess a possible in vitro interaction of lithotripter shock waves and anticancer drugs have been analyzed [1 -4 ] . Our experiments have shown that the cytotoxic effect of cisplatin in L1210 mouse leukemia cells is enhanced more than sixfold by additional exposure of the cells to shock waves [5]. The effect of shock waves was only present when they were applied during incubation with the drug. Since cisplatin crosses the cellular membrane relatively slowly, it was speculated that the interaction of lithotripter shock waves and cisplatin in vitro is based on a short-lived increase in cell membrane permeability. Propidium iodide (PI; 50 /zg/ml), an intercalating dye used to measure cellular DNA content [6], and excluded from viable cells with an intact cell membrane [7], was used to demonstrate a short-lived, higher membrane permeability. Dichlorodihydro fluorescein diacetate (FDA; 50/~g/ml) was employed to identify viable cells by their capability to remove acetate f rom nonfluorescent FDA which is then oxidized to fluorescent fluorescein [8]. Two-color flow cytometric analysis of fluorescence after staining with PI and FDA allowed demonstration o f probe uptake by the cells. This method was originally used to estimate cell survival and the results obtained were shown to correspond to cell proliferation as determined with the soft agar clonogenic assay and the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay [9]. L1210 cell suspensions (2.5 ml; 2 × 106 cells/ml) in polypropylene vials were exposed to 250 shock waves generated at 25 kV with an experimental Dornier

Palmitic acid released from honeybee worker larvae attracts the parasitic mite Varroa jacobsoni on a servosphere

Abstract: Interf. Sci. 44, 330 (1973); Pieranski, P. : Contemp. Phys. 24, 25 (1983) 2. Pusey, P. N., van Megen, W.: Nature 320, 340 (1986) 3. Okubo, T.: Acc. Chem. Res. 21, 281 (1988) 4. Ottewill, R. H. : Langmuir 5, 4 (1989) 5. Williams, R., Crandall, R. S., Wojtowicz, P. J.: Phys. Rev. Lett. 37, 348 (1976); Chaikin, P. M., Pincus, P., 6. 7. Alexander, S.: J. Coll. Interf. Sci. 89, 555 (1982); Robbins, M. O., Kremer, K., Grest, G. S.: J. Chem. Phys. 88, 3286 (1988) Okubo, T. : ibid. 95, 3690 (1991) Nieuwenhuis, E. A., Vrij, A.: J. Coll. Interf. Sci. 72, 321 (1979); Ackerson, B. J., Clark, N. A.: Faraday Discuss. Chem. Soc. 76, 219 (1983); Aastuen, D. J. W., Clark, N. A., Cotter, L. K.: Phys. Rev. Lett. 57, t733 (1986); Smith, D. J., Petford-Long, A. K., Wallenberg, L. R., Bovin, J. O.: Science 233, 872 (1986); Okubo, T. : Ber. Bunsenges. Phys. Chem. 91, 516 (1987); Okubo, T.: J. Chem. Soc., Faraday Trans. 86, 2871 (1990); Okubo, T.: J. Am. Chem. Soc. 112, 5420 (1990) 8. Okubo, T.: J. Chem. Soc., Faraday Trans. 84, 4161 (1988) 9. Boistelle, R., Astier, J. P.: J. Cryst. Growth 90, 14 (1988)

Cochlea size in extant chiroptera and middle eocene microchiropterans from messel

Abstract: The question of monoor diphyletic origin of bats and the systematic status of the oldest known bats from the Eocene of Europe and North America has been the subject of controversy [ 1 6]. It is now generally accepted that all of these Eocene bats are microchiropterans and not ancestors of either Microor Megachiroptera as formerly proposed [2]. For the species Icaronycteris index Jepsen 1966, Early Eocene of Wyoming, and Palaeochiropteryx tupaiodon Revilliod 1917, early Middle Eocene of Germany, it was reported that the size of the cochlea is as large as in extant Microchiroptera, and it was concluded that the echolocation system of these Eocene species was already very sophisticated [4, 7]. This was considered as one argument (among various others) for a diphyletic origin of Microand Megachiroptera [6]. It was, however, not clear whether the data base was sufficient for these conclusions. The aim of the present study is to establish the relations of cochlea size of six fossil species of three families from Messel and 298 extant chiropterans of all major higher taxa. A relationship between cochlea size and echolocation performance has been suggested for some selected extant species [8], but a systematic study has not been undertaken so far. Thus, an evaluation of the relative size of the cochlea for Early Tertiary bats may be achieved by comparison with taxa of extant bats with known echolocation and foraging behavior [9-11] . We provide in this paper a representative sample of 147 species of 28 genera of

An amino acid derivative as the sex pheromone of a scarab beetle

Abstract: Since the identification of bombykol, a myriad of compounds have been reported as sex pheromones. Nevertheless, as highlighted by the examples of female Lepidoptera, which by and large utilize alcohols, acetates, aldehydes, and hydrocarbons, including epoxyhydrocarbons, pheromones are restricted to some groups of chemicals with marked structural similarities. Even in the Coleoptera, with more diversity in molecular structures, structurally related compounds are used by insects of the same family as evidenced by the scarab beetles; the sex pheromones of Popillia japonica, Anomala rufocuprea, and A. cuprea are (R,Z)-5-( )-(dec1 -enyl)oxacyclopentan-2-one [1], methyl (Z)-tetradec-5enoate [2] and (R,Z)-5-(-)-(oct-l-enyl) oxacyclopentan-2-one [3], respectively. On the other hand, Costelytra zealandica and Kheper lamarcki of the same family have been reported to utilize quite different chemicals, viz., phenol [4] and a mixture of hexadecanoic acid, 2,6-dimethyl-5-heptenoic acid, and (E)-nerolidol along with a polypeptide pheromone carrier [5], respectively. We report here that the large black chafer Holotrichia parallela (Mots.) (Coleoptera: Scarabaeidae), ookurokogane in Japanese, utilizes a unique sex pheromone, L-isoleucine methyl ester. H. parallela is an important agricultural pest in Japan, which was initially called Lachnosterna morosa Waterhouse [6] and later renamed [7].

Corticosterone levels of passerine birds during migratory flight

Abstract: 5 n= 21 r--1 6 Fig. 3. Bite response of workers to the nest-mate worker that was spread with a particular crushed organ. Treatment: I hindgut of ergatoid male, 2 midgut and Malpighian tubes of ergatoid male, 3 testes, seminal vesicles and cuticular part of gaster tip of ergatoid male, 4 hindgut of worker, 5 midgut and Malpighian tubes of worker, 6 poison and Dufour's glands and cuticular part of the gaster tip of worker ner with their long mandibles [6]. Thus, ergatoid males might have solved the dilemma between mating and fighting efficiencies by elongating the mandibles and developing a bite-inducing pheromone. In any event, the ergatoid male of C. wroughtonii is a good example of extreme creatures resulting from sexual selection.

The genetics of social behavior in a polygynous ant

Abstract: Division of labor among workers is an integral part of social behavior in ants. Worker specialization on tasks is thought to increase colony-level fitness and thereby contribute to the maintenance of eusociality [1]. Task specialization in ants has been correlated with the environment, age, and size of workers [2]. In this report I demonstrate that intracolony genetic variability exerts a pronounced influence on worker division of labor. In ant colonies, genetic variability is often increased by polygyny; two or more functional queens contribute their own genetically distinct offspring to a single worker population [3]. In polygynous colonies of the ant Formica argentea I first documented division of labor and then assigned individuals to familial lines using an electrophoretic analysis. Significant behavioral biases among lineages were detected in all five colonies examined. These findings may have important implications for the role of genetic variation to social evolution. The discovery of a genetic component to division of labor in another eusocial insect, the honeybee Apis mellifera, has generated considerable interest in genetic analyses of social behavior [4]. Honeybees are polyandrous; multiply mated queens produce assemblages of genetic subfamilies similar to those in polygynous colonies [5]. The propensity for honeybee patrilines within a colony to perform different tasks has been demonstrated in studies using selected strains [4, 6] and in one study using colonies under more natural conditions [7]. In ants, one study has suggested that differences in foraging frequency in Leptothorax rudis was due to the genetic backgrounds of the workers [8]. The colonial subgroups in this case were young workers cross-fostered from separate monogynous colonies. A similar cross-fostering experiment using Camponotus planatus, a polygynous species, showed a number of behavioral differences among sib groups (N. F. Carlin, S. Cover, personal communication). However, neither experiment controls for the effects of separate rearing environments and immediate posteclosion experience; the environment of both larvae and young workers can have an effect on adult behavior [9]. In the experiments in this paper I avoid the problems inherent in artificial construction of worker populations by using naturally constituted polygynous colonies. Colonies of the ant Formica argentea containing two or three queens are common. Because this species has a seasonal reproductive cycle, distinct age groups occur in colonies. In the spring, May to June, the queens lay eggs in the nests. By the end of June, pupae begin to appear in nests and most pupae eclose toward the end of July. In August, pupae finish eclosing and no brood remains. Colonies were collected in their entirety before pupal eclosion and returned to the laboratory where all workers and queens were marked by gluing individual numbers on their abdomens. Only the older, over-wintered workers present at this time were used in the behavioral assay. The colonies were placed into glasstopped horizontal nest boxes to allow for observations. The ants confined their nesting area under a square of red cellophane placed on one corner of the glass top. Undisturbed colonies were scanned 20 times over a period of 3 days so that for each scan sample, the identity of each worker performing social grooming, donating food to nestmates, patrolling the nesting arena, guarding a queen, or maintaining the nest was ascertained. The workers that guarded the queens stood beside or facing a queen, sometimes with open mandibles. Nest-maintenance workers constructed a barrier around the nesting area and maintained that barrier; small pieces of wood were supplied to each colony, which allowed me to distinguish this behavior unambiguously. The workers patrolling the nesting arena walked along the borders of the arena and were also characterized by standing at the nest barrier. Allogrooming involved the cleaning of an individual by another worker. Donating food refers to liquid food exchange (trophallaxis) among workers. Migratory behavior was recorded over an additional 3 days of scan sampling. The workers that led migrations responded to a change in the position of the red cellophane by transporting nestmates and brood. Individual ants were subjected to starch gel electrophoresis [10] so that for each colony, one polymorphic marker protein was used to distinguish allozyme phenotypes. The subgroups were differentiated by the allozyme phenotypes of the marker proteins hexokinase (HK) or 6-phosphogluconate dehydrogenase (6PGD). Both of the allozymes HK and 6PGD had two marker alleles, slow (S) and fast (F), and workers belonged to one of three allozyme phenotypes (SS, SF, FF). In colonies 2.7 and 2.9, the genetic subgroups were representative of single familial lines. In both of these colonies the two queens were SS homozygotes and the workers were either SS or SF. In each case it is likely that one queen mated with a male containing the F allele to produce SF workers, while the other queen mated with a male of the S allele to produce SS workers. Queens appear to be singly inseminated [11], making the assignment of workers to familial lines unambiguous. The allozyme phenotypes of the queens in colony 2.3 were unknown. For this colony and for the three-queened colonies 4.1 and 5.1 the allozyme-phenotype subgroups may have been composed of one or more lineages. Col-

Nuclear fission reactors as energy sources for the giant outer planets

Abstract: Of the giant planets, Jupiter, Saturn, and Neptune presently radiate into space approximately twice as much energy as they receive from the Sun; Uranus, however, emits little, if any, energy other than absorbed solar energy. Currently, speculative explanations for the energy sources involved propose gravitational potential energy release. The purpose of the present paper is to suggest the possibili ty of naturally occurring nuclear fission reactors in the giant outer planets. The discovery of a natural ly occurring, terrestrial, nuclear fission, \"breeder\" reactor is reviewed. Quanti tat ive estimates are made of the planetary energy release by nuclear fission and of the durat ion that present planetary power output levels could be sustained by nuclear fission energy. O bservations made from ground-based observatories, from high-altitude jet aircraft, and from Pioneer and Voyager spacecrafts show that Jupiter, Saturn, and Neptune presently radiate into space approximately twice as much energy as they receive from the Sun; Uranus, on the other hand, emits little, if any, energy other than absorbed solar energy [1-11] . Quantitative estimates of planetary thermal emission to absorption ratios are presented in Table 1. Although observations of large excess radiant flux from the giant outer planets were confirmed over 20 years ago [12], explanations of the heat sources responsible are yet speculative. The central interior temperature of Jupiter, thought to be the highest of the internal temperatures of the gaseous planets, is estimated from numerical model calculations to be approximately 20000 K [13, 14]. Because this temperature is more than two orders of magnitude too low for the occurrence of stellar-type thermonuclear fusion reactions involving nuclides of hydrogen and helium [15-18] , other ideas of potential heat sources have been suggested. An idea has been discussed suggesting that a portion of the excess energy flux is caused by relic primordial heat originally produced by gravitational collapse during planetary formation [19]. Another idea that has been discussed suggests that a portion of the excess energy radiated into space is due to gravitational potential energy liberated during the precipitation of helium in the metallic hydrogen planetary core [20 241. -

Signaltransduktion in Sehzellen

Abstract: concentration. This review describes our present knowledge about the signal transduction and its fine tuning by a complex network of Ca2+-mediated processes in vertebrate photoreceptors.

Neues vom Ontong-Java-Plateau (Westpazifik)

Abstract: For the investigation of climatic history for the last 65 million years, several holes were drilled in 1990 on the Ontong Java Plateau by the drilling vessel Joides Resolution, under the auspices of the international Ocean Drilling Program. The Ontong Java Plateau is the largest basalt plateau on earth, and was formed in the Middle Cretaceous. From the core material, seismic reflectors from the overlying sediments can be associated with specific, climate-related oceanic events. For the cyclic sediments of the last 2 million years, high-resolution isotope curves were generated which depict the two dominant Milankovitch cycles with periods of 100 000 and 41000 years.

Heterospecific substances in the postpharyngeal gland secretion of ants reared in mixed groups

Abstract: 1. Prestwich, G. D.: Biochem. Syst. Ecol. 7, 211 (1979) 2. LindstrSm, M., Norin, T., Valterov~t, I., Vrko~, J. : Naturwissenschaften 77, 134 (1990) 3. Everaerts, C., Bonnard, O., Pasteels, J. M., Roisin, Y., K6nig, W. A.: Experientia 46, 227 (1990) 4. Treibs, W., Merkel, D.: Die Atherischen Ole, Vol. Ilia, p. 118 (E. Gildemeister, F. Hoffmann, eds.). Berlin: Akademie-Verlag 1960 5. Valterov~i, I., Kfe~ek, J., Vrko6, J.: Biochem. Syst. Ecol. 17, 327 (1989) 6. Vrko~, J., Ubik, K., Dolejg, L., Hrd~, ][.: Acta Entomol. Bohemoslov. 70, 74 (1973) 7. Lindstr0m, M., Norin, T., Roeraade, J.: J. Chrom. 513, 315 (1990) 8. Panicker, P. M. B., Rao, B. S., Simonsen, J. L.: J. Indian Inst. Sci. 9A, 133 (1926) 9. Krestinskii, V., Liverovskii, A., Maimberg, V. : J. Prakt. Chem. 129, 97 (1931) 10. Naves, Y. R.: Parr. Cosm. Sav. 12, 586 (1969) 11. Norin, T. : Ark. Kemi 22, 123 (1964) 12. K6nig, W. A.: Gas Chromatographic Enantiomer Separation With Modified Cyclodextrins. Heidelberg: Hiithig 1991

Mutual exclusion as a mechanism for information exchange within ant nests

Abstract: Social insect colonies represent systems of units interacting concurrently [1]; such systems occur in ecology [2], neurobiology [3], and computer science [4]. We show how the phenomenon of mutual exclusion, a fundamental organizing principle in computer science [5], may operate in the nests of the ant L e p t o t h o r a x a c e r v o r u m as a mechanism for information exchange. Division of labor into castes has been observed in many species of social insects. In ants, castes may differ morphologically (physical polyethism) or in the age of their members ( temporal polyethism) [6]. Control of worker action is decentralized; no single individuals (including queens) have been found to direct the actions of other workers [7]. Division of labor and concurrent operations are thought to increase the reliability of task performance [1], but lead to the need for informat ion exchange between units, in that no individual worker has direct knowledge of the colony state (for instance, resource levels and which tasks should receive priority). Similarly, within castes, workers must exchange informat ion to locate shortfall or surplus in task performance. With reference to the nurse caste, workers must interact to determine which items of brood currently require attention. Brood tending (in the form of feeding, cleaning, and sorting) comprises a substantial propor t ion of the colony time budget: in leptothoracines, nurse workers spend up to 40 0/0 of their active time engaged in brood care [8-111. Successful growth and development of brood depends upon adequate feeding and regular cleaning to prevent the

Coexistence and dominance among queens and mated workers in the ant Pachycondyla tridentata

Abstract: Hengstenberg, B.: Proc. R. Soc. Lond. 227, 455 (1986) 2. G6tz, K. G., Hengst~nberg, B., Biesinger, R.\" Biol. Cybern. 35, 101 (1979) 3. Steinman, R. M., Kowler, E., Collewijn, H.: Vision Res. 30, 1845 (1990) 4. Hausen, K., in: Photoreception and Vision in Invertebrates (M. A. Ali, ed.). New York-London: Plenum 1984 5. Ibbotson, M. R. : J. Comp. Physiol. A 168, 91 (1991) 6. Milde, J. J., Seyan, H. S., Strausfeld, N. J. : ibid. 160, 225 (1987) 7. Maddess, T., DuBois, R. A., Ibbotson, M. R.: J. Exp. Biol. 161, 171 (1991) 8. Maddess, T., Laughlin, S. B.: Proc. R. Soc. Lond. 225, 251 (1985) 9. de Ruyter van Steveninck, R. R., Zaagman, W. H., Masterbroek, H. A. K.: Biol. Cybern. 54, 223 (1986) 10. Borst, A., Egelhaaf, M.: ibid. 56, 209 (1987) 11. Kunze, P.: Z. Vergl. Physiol. 44, 656 (1961) 12. Wolf-Oberhollenzer, F., Kirschfeld, K. : Naturwissenschaften 77, 296 (1990)