Showing papers in "Naturwissenschaften in 1991"

Pineal hormone melatonin oscillates also in the dinoflagellate Gonyaulax polyedra

Abstract: Periodic organization represents the basis for temporal orientation corresponding to environmental changes in illumination. The cyclicity in the diurnal light/dark zeitgeber, however, has to be transformed into chemical signals in order to become interpretable by organisms. In our view, it is remarkable that valuable information is not restricted to the presence, but is also provided by the absence of light. With regard to photoperiodism, higher vertebrates, in fact, make preferential use of this latter information and transform the signal \"darkness\" into a high concentration of a chemical mediator, the pineal \"night hormone\", melatonin [ 1 31. The occurrence of melatonin, however, is not restricted to vertebrates. This indoleamine has been shown to exist in insects, too [ 4 7], and to exert effects on reproduction even in planarians [8]. In the dinoflagellate Gonyaulax polyedra, we have recently demonstrated the presence of the enzymes of melatonin formation from serotonin, i.e., indoleamine (\"serotonin\") N-acetyltransferase and hydroxyindole Omethyltransferase [9]. Here, we report on a diurnal rhythm of melatonin concentration in this unicellular organism. Gonyaulax polyedra was grown at 20°C, in a light-dark cycle of 12:12 h (1200:0 Ix; for further details see [11]). Determinations of melatonin by HPLC were based on samples of at least n = 4; maxima were verified on larger samples (1.5 h after lights-off: n = 20; 3 h in darkness: n = 15; 6 and 7.5 h in darkness: n = 12). In the case of RIA, samples amounted in general to n = 5; again, maxima were based on larger numbers (1.5 h in darkness: n = 15; 3 h in darkness: n = 12). Melatonin can be detected in material from Gonyaulax only if special, preservative extraction procedures are applied. Even after denaturation of cell protein, extracts still contain components which can easily destroy melatonin, in particular, after exposure to light [10]. Therefore, the entire procedures were carried out in darkness or dim red light. Melatonin was measured by two independent methods, reversephase HPLC with on-line electrochemical detection, and RIA. Each technique required a particular extraction procedure. In the case of HPLC, cells from 2.7 1 of densely grown Gonyaulax cultures [11] were concentrated to 1 ml by passing them through an 8-/tm mesh membrane filter (Sartorius, GOttingen). This cell suspension was mixed with 1 ml of 1 M Tris-HC1 buffer, pH 8.4, shock-frozen with liquid nitrogen, and pulverized in a mortar; 300 mg of this powder were thoroughly shaken with 300 /zl of 0.4 N PCA containing 0.1 °7o Na2S20 5 and 0.05 °70 EDTA, and extracted for 15 min at 4°C. Precipitates were sedimented for 15 min at 12000 g, and 200 /zl of the supernatant were injected into the HPLC system. Indole compounds including melatonin were separated by isocratic HPLC (Du Pont) on a 10-/zm C18 reverse-phase column, and measured electrochemically (detector: Metrohm) at a potential of 990 mV. The eluent consisted of 2007o methanol, 3.75 g NaH2POJl , 11.25 g citric acid/l, 320 mg octane sulfonic acid/l, and 32 mg EDTA/I (flow rate 0.75 ml/min). Peak identity with melatonin was verified by co-elution with standards under varying elution conditions. The detection limit was 50 pg/200 /,1 injected load. For determination of melatonin by RIA, 1 ml of concentrated Gonyaulax suspension, prepared from 1.35 1 of culture as described, was mixed with 1 ml of 0.1 M tricine NaOH buffer, pH 7.8. After shock-freezing in liquid nitrogen and pulverization in the mortar, 300 mg of powder were extracted with 900 /,1 of acetone for 30 min at 20 °C. A 12000-g supernatant was diluted with an equal volume of water and lyophilized. The lyophilizate was dissolved in 0.1 M tricine NaOH buffer, pH 7.8, containing 9 g NaC1/1, 1 g gelatin/l, and 1 g sodium azide/1, and assayed by RIA [12] using the highly specific antibody batch no. GS 704-6483 from Guildhay Antisera (Guildford, UK). Bound tritium-labeled melatonin was determined by a scintillation proximity assay, on the basis of a double antibody procedure using anti-sheep immunoglobulin bound to scintillator-containing microspheres (Amersham, Braunschweig). Accuracy and specificity of the assay were verified according to criteria of serial dilution, parallelity, and crossreactivity with various tryptophan metabolites. The detection limit of RIA was 10 pg/ml. Protein concentration was determined using a microversion of the method in [13]. In Gonyaulax polyedra, the existence of melatonin can be demonstrated by the two entirely different techniques of reverse-phase HPLC and RIA. Both methods yielded similar data on cellular melatonin content and its diurnal pattern. The amounts of this indoleamine were surprisingly high in the dinoflagellate, reaching values observed in mammalian pineal glands [14, 15]. The concentration of melatonin oscillates within the diurnal cycle, showing a typical pattern (Fig. 1) characterized by a rapid increase after lights-off, followed by a maximum as early as 1.5 h after lights-off, and a subsequent gradual decline already during night, reaching minimal values in the light phase. The diurnal time course of melatonin in Gonyaulax shows remarkable similarities to patterns seen in vertebrates [1 -3 , 14, 15]. The most striking conformity is the strong increase after the onset of darkness. As in

Glycoprotein glue beneath a spider web's aqueous coat

Abstract: The garden spider's web filters from the air insects that arrive with considerable kinetic energy. Critical for the absorption of this energy are the tensile strength and extensibility of the silk [1, 2]. To channel this energy, the fine threads must stick firmly to the prey rather than slide off. Thus, adhesiveness may be as important to a web's success as the mechanics of its silk [3]. Although thread mechanics has recently attracted much attention [ 4 8 ] , next to nothing is known about the glue. We have now identified the glue in the web of araneid orb spiders as microscopic nodules made of glycoprotein. The nodules sit astride the capture threads beneath the visible droplets. The finding puts to rest the old notion that the viscous coat itself is the principal adhesive, whereas in reality it is a water reservoir that maintains thread elasticity [6, 8] and also supports glue formation. Orb webs and their builders fall into two categories classified by the silk that renders the web sticky. Cribellate spiders use very fine silk of nm diameter which they comb, in hackled bands of several hundred threads at a time, onto support threads of/~m diameter [9]. We do not understand how this hackled silk functions nor do we understand the mechanism of its adhesiveness [9]. Ecribellate spiders (e.g., the garden cross spider Araneus diadematus) lack cribellure silk. Instead they catch insects using threads of #m diameter coated with an aqueous solution that forms droplets. Coat and droplets are crucial for the function of the capture spiral [8]. The high water content of the coat (80 %) plasticizes the threads and renders them elastic [6]. The droplets, powered by surface tension, keep the threads tight by reeling them in when slackened and unraveling them again when stretched [8]. Chemical analysis of the coat shows high concentrations of five major water-soluble organic compounds [10] and low concentrations of inorganic salts [11, 12] as well as one or more glycoproteins [13 16]. These glycoproteins are the only identified compounds that have sufficiently long side chains to act as glue sensu strictu rather than adhere by virtue of being a highly viscous solution. We now report that the glycoprotein may be concentrated inside distinct structures, nodules that sit astride the capture threads. The nodules, "droplets within droplets" [17], have so far been ignored by research and textbooks on spider orb webs. We have studied nodule morphology, development, function, and chemistry. Nodules, along with the droplets of the viscous coat, form within minutes after the sticky silk has been laid down (Fig. l a c ) . In Araneus, like all ecribellate orb weavers, sticky silk is confined to the capture spiral and consists of a pair of core threads each paid out f rom the central spigot of a triad, the other two spigots providing the aqueous solution of the coat [18]. The two threads immediately merge and the coat flows into distinct droplets connected by a fine layer of liquid [19]. We observed that nodules and droplets correlated in spacing as well as size

Aerial docking by hummingbirds

Abstract: Strassmann, J. E., Hughes, C. R., Queller, D. C., Turillazi, S., Cervo, R., Davis, S. K., Goodnight, K. F. : Nature 342, 268 (1989) 11. Gadagkar, R.: J. Genet. 70, 1 (1991) 12. Gadagkar, R.: Curr. Sci. 59, 374 (1990); Trivers, R. L., Hare, H.: Science 191, 249 (1976) 13. Gadagkar, R. : J. Genet. 69, 113 (1990); Gadagkar, R., Vinutha, C., Shanubhogue, A., Gore, A. P.\" Proc. R. Soc. Lond. B233, 175 (t988); Gadagkar, R., Bhagavan, S., Chandrashekara, K., Vinutha, C.:Ecol. Entomol. (in press); Gadagkar, R.: Phil. Trans. R. Soc. Lond. B 329, 17 (1990); Gadagkar, R. : Proc. Nat. Acad. Sci. USA (in press)

A linear dominance hierarchy regulating reproduction and polyethism of the queenless ant Pachycondyla sublaevis

Abstract: In the vast major i ty of ants, females are divided into two morphological ly distinct castes: queens which principally perform reproduct ion and workers which are engaged in other tasks. However, some species o f the primitive subfamily Ponerinae have no morphologically distinct queens. In the queenless colonies of such species as Rhytidoponera metallica [1], Rhytidoponera sp. 12 [2], and Ophthalmopone berthoudi [3], reproduct ion is performed by several workers that have fortuitously succeeded in mating. In the queenless species Diacamma australe [4] and D. rugosum [5], however, colonies have only one mated egg-layer, called a gamergate. Their reproductive dominance is controlled by a unique mechanism, in which retention of a pair of thoracic appendages determines mating and reproduction. A single gamergate with vestigial wings controls reproduct ion by inhibiting the mating and oviposit ion of other nestmates whose vestigial wings have been removed by the gamergate soon after their emergence. The colonies of Pachycondyla krugeri also have only one gamergate [6]; however, the mechanism controlling the reproductive dominance is as yet unknown. In the queenless ant Pachycondyla (= Bothroponera) sublaevis we discovered an almost linear dominance hierarchy in which (1) the dominance display was well ritualized with no occurrence of fighting, (2) only a top-ranked worker was inseminated and laid eggs, (3) all colony members other than bo t t omranked workers could develop their ovaries when higher-ranked workers were removed, and (4) higher-ranked workers conducted the care of eggs and larvae and lower-ranked workers were engaged in foraging. In ants, this is the first discovery of dominance hierarchy in which most members of a colony are potential successors of the reproductive female. P. sublaevis belongs to the rufipes group, and occurs in the dry Eucalyptus woodland of nothern Australia. Its colonies are possibly among the smallest of all ants, comprising an average of 9 ( + 2.5 s.d.) workers. In most colonies, only one of these is inseminated and bears a reproductive ovary [7]. The behavior of workers was observed in the labora tory in colonies collected at Mr. Garnet , Nor th Queensland, Austral ia, in October to December of 1987 and 1989. In colony A, comprising 11 workers, antagonistic interactions between individuals were observed 85 times during a total of 42 h of observation (Table 1). In the typical sequence, the dominant worker rapidly lunged her vibrating antennae and aggressively pummeled the head of a subordinate (Fig. 1). She repeated this behavior o n e to eight times in each display. The subordinate crouched with her antennae drawn backward until the dominant ceased her coercive behavior. This dominance display was well ritualized with no occurrence of fighting. Between a given pair of workers, the dominance was unilateral except between No. 10 and No. 30 in which the former was dominant three times and subordinate two times. Al though it was difficult to determine the order among low-ranked workers, who were usually ignored by other nestmates, the dominance hierarchy appeared almost linear with few tripart i te deadlocks. The posit ion in the hierarchy was apt to determine the function of the worker concerned. Only the top worker possessed a sperm-filled spermatheca and a well-developed ovary and actually laid eggs. This gamergate and other highranked workers preferred care of eggs and larvae to foraging, which was mostly performed by low-ranked workers (Fig. 2). Cocoons were most frequently tended by middle-ranked workers.

In situ differentiation between nevi and malignant melanomas by fluorescence measurements.

Abstract: Recently we have shown that melanomas can be detected in situ by their fluorescence response when excited monochromatically with 365 nm [1]. While in all cases investigated (healthy skin, nevi, melanomas) the fluorescence spectra seem to look alike with a maximum at about 470 nm, in melanomas, additional peaks might exist at 445 and 535 nm (nodule). The spectra, however, vary considerably in intensities. Thus, the intensity is very small within the tumor region and rather large in its immediate surroundings if compared with healthy tissue. In a nevous region the fluorescence intensity is not significantly reduced. To apply this fluorescence technique to in situ determination of nevi and melanomas, i.e., to use it as an additional information source for elucidating certain types of skin lesions, we examined additional patients with nevi, so-called dysplastic nevi, and melanomas. E m phasis was put on a controlled study with a large sample size in each group, so that a statistical evaluation of the resuits obtained from these patients was possible. The fluorescence technique applied has been described elsewhere [2]. A total of 147 patients with nevi (59), so-called dysplatic nevi (43), and melanomas (45) were investigated in vivo. The so-called dyplastic nevi were diagnosed according to the criteria established at the consensus conference [3]. In all instances the excised skin probes were examined histologically after surgery. The relevant skin areas were excited in situ with 365 nm using a 100-W Hg high-pressure lamp (Osram) and a BP 366/11 filter (Schott, Mainz) just prior to surgery. The fluorescence light

Nature and Nurture: Environmental Isotope Story of the River Rhine

Abstract: The total dissolved load of the Rhine river increases downstream due to the combined impact of natural and pollution loads. The natural background, controlled by geology, is soon swamped by pollution, particularly from salt and coal mining activities in Alsace and the Ruhr area. The Rhine is also a net source of CO2 from oxidation of excess organic productivity that is fuelled by nutrient pollution, a problem even more serious for some of its tributaries.

Genome exclusion and two strategies of chromosome duplication in oogenesis of a hybrid frog

Abstract: To date about 50 naturally-occurring vertebrate taxa of hybrid origin are known to reproduce by parthenogenesis (no sperm is needed for development), gynogenesis (sperm is not incorporated after activation of development and inheritance is matroclinous), or hybridogenesis (a zygote fusion nucleus is formed, but one parental genome is selectively eliminated during the hybrid's gametogenesis) [1]. Amniotes (reptiles) are parthenogenetic, anamniotes (fish and amphibians) are gynogenetic or hybridogenetic. Each of these aberrant modes of reproduction demands some remarkable modification in gametogenesis, such as premeiotic endomitosis (duplication of chromosomes), or genome exclusion (loss of one parental genome) [2]. Premeiotic endoduplication is believed to be the mechanism by which most vertebrate parthenogens and gynogens maintain their somatic ploidy. This is based on studies of meiotic chromosomes, but in fact, a premeiotic chromosome duplication has never been demonstrated [3]. Genome exclusion occurs in the few known hybridogens [4]. The only vertebrates known to exhibit both genome exclusion and chromosome duplication are hybridogenetic European water frogs (the Rana esculenta complex). We have studied the oogenesis in R. esculenta and here demonstrate the selective loss of one parental genome during the period of oogonial proliferation. We also show that a multiplication of haploid oogonia occurs after genome elimination. There is evidence that restoration of diploidy can proceed in two different ways: either by a premeiotic, or by a prediplotene meiotic event. R. esculenta is a widespread hybrid between the species R. ridibunda and R. lessonae. Both parental water frog species have 2n = 26 chromosomes (five large, eight small pairs). Fluo-

Y-chromosome-specific DNA amplified in ancient human bone

Abstract: Here, we report on the enzyme-directed amplification of human Y-chromosome-specific sequences from ancient bone material. This method allows one to identify the sex of skeletal remains on the DNA level

How do bees shiver

Abstract: Many kinds of bees warm up their thoracic flight muscles in preparation for flight [1 3], for heating the colony [1,4], and incidentally while flying [2,5], fanning, buzzing during communication [1], and during pollen collection [6]. During this warm-up the muscles are always activated by muscle potentials. However, it has been difficult to ascertain whether or not once stimulated, the heat is generated via nonshivering (no muscle contractions) or shivering (muscle shortening, either twitches or tetanus). Bumblebees are particularly renowned for their impressive endothermy, being capable of warm-up from air temperatures (Ta) near 6 °C to achieve thoracic temperatures (Tth) over 36 °C in several minutes [2]. Heat output at Tth = 36°C approaches 60 J g thorax 1 min1, some 350 times the resting rate I at 6 °C. It was earlier presumed that the endothermy in the nest and prior to flight was the result of buzzing [8], but subsequent studies showed that Tth increases may occur without any auditory or other detectable thoracic vibrations [2,6]. One mechanism to account for the massive heat production in the absence of thoracic vibrations is that the main power-producing flight muscles, the DL (dorsal longitudinal wing depressors) and DV (dorsoventral wing elevators) go into a tetanus during warm-up. Thus, there would be muscle contraction (i.e., shivering) but little external movement. Alternatively, numerous research reports on bumblebees since 1972 [9,10] and until now [11] give circumstantial evidence for a nonshivering thermogenesis (NST) where the flight muscles engage phosphofructokinase and fructose-l,6-diphosphatase in reactions for a "futile cycling" that burns off ATP, causing heat production but no contraction. According to this model, the muscles are not contracted during warm-up. The release of Ca 2+ from the sarcoplasmic reticulum at the initiation of muscle contractions (flight) then shuts off the NST by inhibiting the fructose1,6-diphosphatase reaction [10]. We show here that this model is untenable. We show that contractions of the flight muscles occur at all Tth during warm-up in the bumblebee, Bombus impatiens. Comparative data in honeybees, Apis mellifera, and carpenter bees, Xylocopa virginica, illuminate the details between the role of the main flight muscles and various mechanical responses of the thorax. As predicted by the anatomy of the honeybee [12], contractions of the indirect flight muscles (DL and DV) should resuit in slight movements of the scutellum, even though the thorax itself remains stable. In order to detect possible scutellar movement associated with thoracic muscular contractions we mounted bees by suspending them from a small wooden rod glued onto the notum of the thorax with tacky wax (Fig. 1). A small, light plastic mirror was glued onto the middle of the scutellum. A horizontal bar of dc-light was reflected off this mirror onto a photovoltaic cell which was partially shielded so as to expose only a downward pointing triangle. In this arrangement an upward deflection of the light beam on the triangle resulted in increased voltage, and a downward deflection to the narrow portion of the exposed photocell resulted in decreased voltage. One or more wire electrodes (diameter 50/zm, insulated except for the tip) were inserted in the DL and DV muscles. A reference electrode was pushed through a small hole in the head. A copper-constantan thermocouple (72/zm diameter) was waxed to the middle of the frontal dorsal thorax to determine muscle temperature [1]. A second thermocouple 1 cm above the animal recorded air temperature (Ta). All of the signals were observed on oscilloscope screens and simultaneously recorded on the instrumental tape recorder in FM mode (Vetter Model B). Samples were stored and analyzed in an IBM PS 2 computer. Ten Bombus, 15 Apis and 3 Xylocopa were subjected to ambient room temperature (20 to 25 °C) and to cooling to 5 °C by packing ice around them. They alternated

Temporal pheromonal and kairomonal secretion in the brood of honeybees

Abstract: In a honeybee colony, brood care is ensured by adult bee behavior adapted to the different ages and castes of larvae. The brood is incubated, the larvae are fed, and their cells are capped [ 1 3]. In order to adopt the appropriate behavior, adult workers must be able to recognize the age and the caste of a larva. Like most social Hymenoptera, chemical signals play an essential role in brood recognition for the honeybee [4]. When the worker larvae are 9 days old (from the time of egg-laying), adult bees close the top of the brood cell with a wax cap [5]. This behavior can be artificially triggered by four of the ten methyl and ethyl fatty acid esters present on the surface of larvae: methyl palmitate, methyl oleate, methyl linoleate, and methyl linolenate (MP, MO, ML, MLN) [6]. The six other fatty acid esters identified in the larval cuticle are: ethyl palmitate (EP), methyl stearate (MS), ethyl stearate (ES), ethyl oleate (EO), ethyl linoleate (EL), and ethyl linolenate (ELN). The parasitic mite, Varroa jacobsoni, reproduces on the brood of honeybees. It is attracted by worker and drone larvae just before their cells are capped, and reproduces in the sealed cell until the adult bee emerges at 21 days of age. Among the compounds present in cuticular larval extract, only three esters methyl and ethyl palmitates, and methyl linolenate (MP, EP, MLN) are attractive to Varroa [7]. Thus, two of these esters act both as pheromones and as kairomones. It seems likely that the presence of these esters in the larval cuticle on the 9th day is responsible for both the entry of Varroa females into the cells and for the capping behavior of workers. This hypothesis is now supported by evidence

Sweet food means “Hot Dancing” in honeybees

Abstract: 1. Nelson, D. A.: Behaviour 106, 158 (1988) 2. Adret-Hausberger, M. : Bioacoustics 2, 137 (1989) 3. Moore, B. C. J.: An Introduction to the Psychology of Hearing. London: Academic Press 1989 4. Heil, P.: Dissertation Techn. Univ. Darmstadt (1989) 5. Klump, G. M., Maier, E. H. : J. Comp. Psychol. 104, 94 (1990) 6. Langemann, U., Klump, G. M. : submitted 7. Sinnott, J. M., Sachs, M. B., Hienz, R. D. : J. Comp. Physiol. Psychol. 94, 401 (1980) 8. Hienz, R. D., Sachs, M. B., Sinnott, J. M.: J. Acoust. Soc. Am. 70, 699 (1981) 9. Hienz, R. D., Sinnott, J. M., Sachs, M. B. : J. Comp. Physiol. Psychol. 91, 1365 (1977) 10. Kreithen, M. L., Quine, D. B.: J. Comp. Physiol. 129, 1 (1979) 1l. Dooling, R. J., Okanoya, K., Downing, J., Hulse, S.: Bull. Psychonom. Soc. 24, 462 (1986) 12. Mfiller, C. M. : Neurosci. Lett. 77, 272 (1987) 13. M~iller, C. M., Scheich, H.: J. Neurophysiol. 59, 1673 (1988)

The role of two distinct subunit types in the architecture of keyhole limpet hemocyanin (KLH)

Abstract: Hemocyanin is a giant extracellular respiratory protein responsible for the blue blood of many mollusks, including cephalopods, chitons, some bivalves, and many gastropods. The active site of molluscan hemocyanin contains two copper ions and resembles that of arthropod hemocyanin, but the two protein classes differ remarkably in their primary and quaternary structure, suggesting that they evolved independently from a premordial monocopper protein [1]. Molluscan hemocyanin is based on a ~ 400 kDa polypeptide (= subunit) folded into a \"pearl chain\" of seven to eight immunologically distinct domains, each carrying a binuclear copper site. In cephalopods, ten such subunits constitute cylindric decamers with a three-tiered wall (Mr ~4 MDa), whereas in pulmonate snails there are twice as large \"di-decamers\" with a sixtiered wall [2, 3]. In prosobranch and opisthobranch gastropods, and in some bivalves, besides solitary di-decamers, tubular \"multi-decamers\" are found, consisting in a di-decamer plus one or several decamers associated at either end [4 6]. In arthropod hemocyanins, which are hexamers or oligohexamers of a subunit of M r ~ 75 kDa, specific linker subunits enable them to go beyond the basic hexamer, leading to a whole panopticum of subunit types in the larger aggregates [7]. On the contrary in mollusks, decameric Octopus dofleini hemocyanin as well as di-decameric Helix pomatia hemocyanin require only a single subunit type [8, 9]. In some prosobranchs, however, the existence of two different subunits was noted [1013], but it has remained unclear whether this has something to do with the formation of multi-decamers. Recently, four different causes that

(R,Z)-5-(−)-(Oct-1-enyl)oxacyclopentan-2-one, the sex pheromone of the Scarab Beetle Anomala cuprea

Abstract: The cupreous chafer beetle Anomala cuprea Hope (Coleoptera: Scarabaeidae), douganebuibui in Japanese, is one of the most severe agricultural pests in Japan, which attacks a wide variety of crops both in the larval and adult stages. Because of the demand for safer agrochemicals (and the difficulty to control the pest with insecticides), the elucidation of behavior-modifying chemicals of potential use in pest management of the beetle is of utmost importance. However, pheromone identification in scarab beetles has been restricted to only a few species, mainly the Japanese beetle Popillia japonica [1] and the soybean beetle Anomala rufocuprea [2]. Preliminary works with the cupreous chafer were unrewarding [3], probably due to the complicated communication system of the insect. Furthermore, it has been considered that this insect does not use sex pheromones because of its gregarious nature. In fact, A. cuprea possesses a sex pheromone, whose full identification as (R, Z)-5-( )-(oct1-enyl)oxacyclopentan-2-one (1) is described here (Fig. 1).

Cuticular hydrocarbon profiles : a valuable tool in termite taxonomy

Abstract: they become arrested and eventually assemble near the fecal deposits of their conspecifics. It became evident that populat ions of flour mites coexist in a biocoenotic relationship with certain saprophytic Ascomycetes (Fig. 3). The joint action of the fungal kairomone ammonia and the acarid pheromone guanine results in attraction and subsequent aggregation of flour mites on a substrate which provides an adequate diet for both A. siro and Ascomycetes. Flour mites rarely consume wheat endosperm unless it is moldy [1]; they have a marked nutrit ional preference for certain seedborne fungi [11, 12] and thus contribute to the dissemination of conidia and ascospores.

Formation process of carbyne produced by shock compression

Abstract: As is well known, there are many polymorphs in carbon crystals, i.e., hexagonal graphite, rhombohedral graphite, hexagonal diamond, cubic diamond, soccer ball type (C60), and carbyne forms (orand ~-carbyne [1], chaoite [2], carbon-VI [3]). Of particular interest are the carbynes, chain-like compounds with sp-hybridization and conjugated triple or cumulated double bonds between the carbon atoms in the chain. The carbon chains were assumed to be arranged parallel to the hexagonal c-axis [4]. According to their thermodynamic stability, graphites and carbyne forms can conveniently be grouped into low temperature-low pressure forms and high temperature forms, respectively [5]. So far, carbynes have been produced by polycondensation of acetylene in the presence of a copper catalyst [6], by condensation of carbon vapor generated by the laser heating of graphite to temperatures exceeding 2600 K [7], or as product of regraphitization of diamond formed by explosive loading of the blended mixture of graphite/metallic powder [8, 9]. In the present paper, we deal with the formation process of carbynes which

Evidence for a Polyalkyl Nature of Soil Humin

Abstract: cell water in MC than in BSC. Our results confirmed this. Grana are greatly reduced in chloroplasts of BSC in NAPD-ME plants. Reduction of oxaloacetate to malate in the MC effectively transfers reducing power from the MC to the BSC - most likely enriched in the heavy isotope. In any case, water from the MC was considerably enriched in deuterium relative to the BSC. A considerable fractionation of both hydrogen and carbon isotopes is associated with photosynthesis [7]. Mobilization of the photosynthate and biosynthesis of cellular components result in smaller fractionations. This is seen in the hydrogen and carbon isotopic data for organic matter (Table 1). Hydrogen and carbon isotopic values were taken from water and tissues collected from root, veins (BSC), and intercostal tissue (MC) of Zea mays seedlings. Water from the MC was greatly depleted in the light isotope presumably due to evapotranspiration. These results could help explain the observation that [6, 7] hydrogen isotopic ratios of organic matter in NADP:ME plants are heavy compared with other C 4 plants.

Correlation of7BE concentrations in surface air and precipitation with the solar cycle

Abstract: As a natural tracer the cosmic-rayproduced 7Be has proven to be useful for studying atmospheric transport mechanisms. It is well known that the concentration of 7Be in ground level air and precipitation shows seasonal variations. Feely et. al. [1] reported that the variations in the concentration of 7Be are due to at least four factors: the rate of exchange between the stratosphere and the troposphere, the rate of vertical mixing within the troposphere, the transport of air masses from middle to higher latitudes, and variations in the rainfall rate. We have determined at Munich-Neuherberg the seasonal variations of the 7Be concentrations [2, 8] and the long-term variations of the an-

Identification of the sex pheromone of the Hessian fly,Mayetiola destructor (Say)

Abstract: Wheat is the most widely cultivated plant in the world, providing more than 20 % of the food calories consumed [1]. The Hessian fly, Mayetiola destructor (Say), (Diptera: Cecidomyiidae), is one of the most destructive pests of wheat and is found in most of the major wheat-growing areas of the world [2]. Due to the feeding habit of the larva and the type of damage it produces, early infestations by Hessian fly are extremely difficult to detect or predict. Female Hessian flies are known to produce a sex pheromone that elicits upwind flight by males [3] and, given the widespread use of synthetic sex pheromones in pest management programs [4], it is very likely that this sex pheromone could find great utility in controlling this pest. As well as containing a large number of pest species, the family Cecidomyiidae is of evolutionary interest because of its rapid rate of species formation relative to a lesser rate of speciation in related families of Diptera [5]. We report here the first identification of a cecidomyiid sex pheromone, that of the Hessian fly, as (2S)(E)-10-tridecen-2-yl acetate (Fig. 1). The crude sex pheromone was obtained by dissecting the terminal segments of the ovipositors of female Hessian flies, and extracting them in pentane. The activity of extracts, fractions of extracts, and synthetic chemicals was determined

Seasonal change in the temporal organization of wheel-running activity of the European Hamster, Cricetus cricetus

Abstract: In this paper we demonstrate that a dramatic annual change in the temporal organization of locomotor activity goes hand in hand with the seasonal cycle of reproduction. Activity levels increased when the animals entered reproductive conditions, which occurs naturally in spring and early summer. During the 2-3 months of reproduction, a well-defined activity rhythm was observed. During the rest of the year, the level of activity was dramatically reduced and almost no rhythmic organization was detected. The question arising from these observations is whether the loss of temporal organization reflects a weakening or arrhythmia of the underlying pacemaker or whether it is due to an uncoupling of the overt activity rhythm from the central clock.

Lunar spawning synchroneity in a freshwater fish

Abstract: (in press) 13. Slessor, K. N., Kaminski, L.-A., King, G. G. S., Borden, J. H., Winston, M. L.: Nature 332, 354 (1988) 14. Getz, W. M., Br~ckner, D., Smith, K. B.: J. Comp. Physiol. A 159, 251 (1986) 15. Getz, W. M., Smith, K. B.: ibid. 160, 238 (1987) 16. Moritz, R. F. A., Crewe, R. M.: ibid. 164, 83 (1988) 17. Michelsen, A., Kirchner, W. H., Andersen, A. A., Lindauer, M.: ibid. 158, 605 (1986) 18. Michelsen, A., Kirchner, W. H., Lindauer, M.: Behav. Ecol. Sociobiol. 28, 207 (1986) 19. Vander Meer, R. K., Wojcik, D. P.: Science 218, 806 (1982) 20. HOlldobler, B.: Z. vergl. Physiol. 75, 215 (1970)

Identification of an oviposition-deterring pheromone in the eggs of the European corn borer

Abstract: The European corn borer (ECB) Ostrinia nubilalis (Lepidoptera, Pyralidae), a serious pest of corn is a polyphagous insect which can damage various crops such as cot ton and vegetables [1, 2]. In the United States, the average yield reduction caused by this insect in susceptible corn hybrids in 1986 was 40 % [3]. Females lay masses of 2 0 4 0 eggs mainly on the lower surfaces of the leaves. In this species, the egg masses are often observed at low density levels in the field [4] and the spatial distribution of the egg masses suggests a possible intraspecific regulation of the oviposit ion behavior. We assumed that the egg-laying behavior of this species could be chemically mediated by pheromones present on the egg masses. Oviposit ion-deterring pheromones (ODP) produced by eggs have been observed both in species which lay isolated eggs [5] and which aggregate eggs [6]. ODP can be produced by different sources. Larval frass extracts have been shown to be oviposit ion deterrents in species like Spodoptera littoralis [7] or Ostrinia nubilalis [8]. In most of the investigated species, the chemical nature of the ODP remains unknown. We report the first evidence of the deterrent effect of egg extracts on the oviposit ion behavior of the ECB, and the identification of active components as methyl esters of simple aliphatic acids. We also observed a chemically mediated regulation of the egg mass size. This pheromone may help to explain the distribution of ECB egg masses on plants and represent a possible mode of chemical control of this pest. The insects studied came from an INRA strain (Le Magneraud, France) annually infused with insects collected

Specific IgG activity of sera from Egyptian schistosomiasis patients to keyhole limpet hemocyanin (KLH).

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