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  • Halictidae  (4)
  • Biochemistry and Biotechnology  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 163 (1989), S. 201-209 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Iridaceae ; Moraea inclinata ; M. brevistyla ; Bees ; Anthophoridae ; Halictidae ; Pollination mechanism ; flower morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Individual flowers ofMoraea inclinata are nectariferous and last about six hours. They appear to be pollinated largely by bees in the familyHalictidae (Lasioglossum spp.,Nomia spp.,Zonalictus) and to a lesser extent by bees in the familyAnthophoridae (Amegilla). The mechanism of bee-pollination inM. inclinata is the “Iris type”; i.e., each flower consists of three pollination units (an outer tepal, a partly exserted anther, and the opposed style branch which terminates in a pair of petal-like crests). Bees rarely visit more than one pollination unit per flower. Transferral of pollen to the bee is passive and nototribic although all bees collected on the flowers were female and 55% of the bees carried pollen loads with 2–5 pollen taxa in their scopae.Moraea brevistyla flowers are nectariferous but lack scent and last two days. They are visited infrequently by bees and only one femaleLasioglossum spec. carried the pollen ofM. brevistyla. Unlike flowers ofM. inclinata those ofM. brevistyla deposit pollen only on the head and thorax. Bee-mediated autogamy in both species is avoided due to the erratic foraging patterns of the bees and the flexibility of each stigma lobe as the bee backs out of the flower. Approximately 2–4 flowers in the inflorescences of both species (6–8 flowers/infloresence) develop into capsules.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 151 (1986), S. 187-202 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Orchidaceae ; Thelymitra nuda ; Liliaceae ; Dichopogon ; Thysanotus ; Halictidae ; Lasioglossum ; Syrphidae. — Mimesis ; pollinaria ; staminodal hood ; thoracic vibration ; trichome cluster. — Flora of Australia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Insect pollination occurred inThelymitra nuda R. Br. on sunny days when the ambient temperature exceeded 20 °C. The flower buds on a raceme opened subsynchronously displaying the brightly-colored, actinomorphic perianth and exposed the contrastingly-colored, scented and ornamented column. InT. nuda the staminodes and the filament of the fertile stamen are fused to one another producing an inflated hood over the anther. This staminodal hood is terminated in two non-ornamental, but brightly-colored, central lobes and two terete lateral lobes bearing approximately 400 white trichomes. Each trichome bears a double chain of 30–40 spherical, rugulose cells. Female bees, in the genusLasioglossum (Halictidae), were observed to land directly on the hood and curled their bodies around the four lobed tip of the staminodal complex. The bees attempted to forage on the lobes as if they were collecting pollen from fertile, poricidal stamens. These bees applied thoracic vibration to the yellowish central lobes and actively scraped the trichome clusters (Pseudopollen) with their forelegs. Bees carried the pollinaria ofT. nuda dorsally on their abdomens. Abdominal contact with the rostellum appeared to occur when the female bee disengaged herself from the staminodal hood. Observations made of bees on co-blooming flowers, and analyses of pollen loads collected by bees suggested that the orchid flower mimics the guild of blue-purple flowers that lack floral nectar but offer pollen in poricidal anthers. The models ofT. nuda are co-bloomingLiliaceae in the generaDichopogon andThysanotus. However, nectarless, buzz-pollinated flowers are also extensively distributed over the orchid’s range. More than 30% of the flowers in theT. nuda population had their pollinaria removed, suggesting a high capacity for cross-pollination in an orchid genus usually considered to be self-pollinated via mechanical autogamy. This study confirmed previous predictions that column modifications represented a trend towards pseudanthery.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 170 (1990), S. 247-255 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Mimosaceae ; Schrankia nuttallii ; Halictidae ; Bee-pollination ; anthecology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Schrankia nuttalii flowers through late spring on the tallgrass prairie. Although each stem produces an average of 26 capitate inflorescences only 12% of those inflorescences will open each day to disperse and receive polyads. Each inflorescence may live up to 48 hours but anthers abscise by late afternoon on the first day and the filaments change color and lose their scent. The 78–93 florets comprising each inflorescence open synchronously before dawn or during early morning hours. First day inflorescences ofS. nuttallii are herkogamous and fragrant. They are nectarless. Bombyliid flies and male bees are infrequent floral foragers so the major pollinators include female bees representing five families;Anthophoridae, Apidae, Colletidae, Halictidae, andMegachilidae. All foraging insects ignore second day inflorescences although stigmas are still receptive. Although 97% of all bees collected onS. nuttallii carrySchrankia polyads in their scopae or corbiculae 59% also carry the pollen/pollinaria of one or more coblooming angiosperms. At least 98% of all bees carrying mixed pollen loads incorporate the pollen/pollinaria of one or more nectariferous taxa (e.g.Asclepias spp.,Asteraceae, Convolvulaceae, Delphinium spec., etc.). Species of halictid bees are more likely to carry pure loads ofS. nuttallii polyads (70%) than bees of the four remaining families. Due to the nectarless florets and high degree of polylectic foraging bee-pollination inS. nuttallii converges more closely with the pollination systems of some AustralianAcacia spp. than with most other xeric/tropical genera of mimosoids studied in the western hemisphere.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 171 (1990), S. 147-155 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Oxalidaceae ; Oxalis violacea ; Andrenidae ; Bombyliidae ; Halictidae ; Megachilidae ; Pollination ecology ; heterostyly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Vernal grass fires may encourage profuse flowering in clonal, colonies ofOxalis violacea. Long-styled colonies appear to be more floriferous than short-styled colonies and set a greater number of capsules. Individual flowers of both morphs live one or two days, change position on their respective pedicels and advertise nectar concealed at the base of the floral throat. AlthoughDiptera, Hymenoptera, andLepidoptera forage for nectar, bees (Andrenidae,Anthophoridae, Halictidae, andMegachilidae) probably make the only effective pollen transfers between the two morphs. Both male and female bees may transport pollen of both morphs and short-tongued bees (e.g.,Augochlorella spp.,Dialictus spp.) may be more common but as effective as pollinators as long-tongued bees (e.g.,Calliopsis andreniformis andHoplitis spp.). The conversion rate of flowers into capsules is only 13–17%. The spreading style in the short-styled morph is interpreted as an adaptation restricting insect-mediated, self-pollination but encouraging bee-stigma contact during nectar foraging.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 11 (1998), S. 2-9 
    ISSN: 0952-3499
    Schlagwort(e): poliovirus ; human poliovirus receptor ; immunoglobulin superfamily ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The ability of a virus to attach to a suceptible host cell is of utmost importance for the initiation of viral life cycle. Cell surface proteins called viral receptors mediate the initial steps of virus attachment and uptake. Poliovirus (PV) is one of the most studied animal viruses and its interaction with its cellular receptor, the human poliovirus receptor (hPVR) has been well characterized. This review will present our current understanding of the PV/hPVR interaction at the genetic and biochemical level. In addition, we will also discuss the implicatlions of the PV/hPVR interaction on PV tissue tropism and the evolution of the three PV serotypes. Copyright © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 6
    ISSN: 0173-0835
    Schlagwort(e): Bacillus subtilis ; Two-dimensional polyacrylamide gel electrophoresis ; Protein index ; Stress proteins ; SigmaB ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Data on the identification of proteins of Bacillus subtilis on two-dimensional (2-D) gels as well as their regulation are summarized and the identification of 56 protein spots is included. The pattern of proteins synthesized in Bacillus subtilis during exponential growth, during starvation for glucose or phosphate, or after the imposition of stresses like heat shock, salt- and ethanol stress as well as oxidative stress was analyzed. N-terminal sequencing of protein spots allowed the identification of 93 proteins on 2-D gels, which are required for the synthesis of amino acids and nucleotides, the generation of ATP, for glycolyses, the pentose phosphate cycle, the citric acid cycle as well as for adaptation to a variety of stress conditions. A computer-aided analysis of the 2-D gels was used to monitor the synthesis profile of more than 130 protein spots. Proteins performing housekeeping functions during exponential growth displayed a reduced synthesis rate during stress and starvation, whereas spots induced during stress and starvation were classified as specific stress proteins induced by a single stimulus or a group of related stimuli, or as general stress proteins induced by a variety of entrely different stimuli. The analysis of mutants in global regulators was initiated in order to establish a response regulation map for B. subtilis. These investigations demonstrated that the alternative sigma factor σB is involved in the regulation of almost all of the general stress proteins and that the phoPR two-component system is required for the induction of a large part but not all of the proteins induced by phosphate starvation.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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