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1.
Emma Bricchi Marco Fornaciari Claudia Giannoni Francesca Greco Daniela Fascini Giuseppe Frenguelli Gianfranco Mincigrucci Bruno Romano 《Aerobiologia》1992,8(3):401-406
Summary Gramineae pollination from a pollen monitoring station located in the eastern suburb of Perugia and meteorological correlations are reported. The data refers to the year 1989. Grass pollen peak pollination was from May to July; in this period the influence of relative humidity and of temperature on pollen concentration was very high. Phenological observations, to identify the time of maximum stamen extension in the most common genera in the area, are also reported. During the period of investigation the counts of pollen grains over four-hour periods showed a regular diurnal rhythm with peaks of concentration in the four-hour period 16.00–20.00. Aerosporological data and meteorological data related to four-hour periods were correlated following different criteria. 相似文献
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Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time. 相似文献
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The study of water relaxation rates of solutions of melanins with paramagnetic metal ions provides a powerful tool for investigating the binding sites and for obtaining useful structural and dynamic information. The measure of 1H- and 2H-longitudinal and transverse relaxation rates at a single, high-magnetic field for H2O/D2O (80:20) solutions allows the determination of tau c, tau R, tau e, tau M, r, q, and Z (the outer sphere contribution to the overall relaxation rate) for Mn(II)-L-Dopa melanin system. 相似文献
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The ultrasonic calls produced by three day old mice when separated from the nest mother and siblings increase in number when naloxone is injected. 相似文献
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Céline Fouquet Bénédicte M. Babayan Aurélie Watilliaux Bruno Bontempi Christine Tobin Laure Rondi-Reig 《PloS one》2013,8(6)
We investigated the neural bases of navigation based on spatial or sequential egocentric representation during the completion of the starmaze, a complex goal-directed navigation task. In this maze, mice had to swim along a path composed of three choice points to find a hidden platform. As reported previously, this task can be solved by using two hippocampal-dependent strategies encoded in parallel i) the allocentric strategy requiring encoding of the contextual information, and ii) the sequential egocentric strategy requiring temporal encoding of a sequence of successive body movements associated to specific choice points. Mice were trained during one day and tested the following day in a single probe trial to reveal which of the two strategies was spontaneously preferred by each animal. Imaging of the activity-dependent gene c-fos revealed that both strategies are supported by an overlapping network involving the dorsal hippocampus, the dorsomedial striatum (DMS) and the medial prefrontal cortex. A significant higher activation of the ventral CA1 subregion was observed when mice used the sequential egocentric strategy. To investigate the potential different roles of the dorsal hippocampus and the DMS in both types of navigation, we performed region-specific excitotoxic lesions of each of these two structures. Dorsal hippocampus lesioned mice were unable to optimally learn the sequence but improved their performances by developing a serial strategy instead. DMS lesioned mice were severely impaired, failing to learn the task. Our data support the view that the hippocampus organizes information into a spatio-temporal representation, which can then be used by the DMS to perform goal-directed navigation. 相似文献
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Determination of urinary delta-amino levulinic acid (ALA) is now systematically used in occupational health to detect an excessive exposure to lead in professionally exposed workers. However, to determine whether circadian changes of the urinary excretion of ALA alter the significance of the test, we quantified the ALA levels in the urine of 19 healthy young adults. Urine samples were taken every 3 hr between 0700 and 2300 hr and ALA levels were determined by a spectrocolorimetric method. The data indicated that the 24-hr mean ALA level was: 1.81 mg/g creatinine. The peak values (2.24 +/- 0.24) were obtained between 1400 and 1700 hr whereas the lowest ALA levels were found between 2200 and 0300 hr. Cosinor analysis revealed a significant circadian rhythm while no significant difference could be found according to sex. Possible explanations of our findings are discussed. 相似文献
8.
Bruno Jirgensons 《Journal of Protein Chemistry》1982,1(1):71-84
The factors determining the onset and extent of reconstructive denaturation of proteins were considered by comparing circular dichroism (CD) data of seven proteins and previously published findings. The effects of sodium dodecyl sulfate (SDS) on the conformation of the following proteins were tested: lysozyme, the mitogens fromPhytolacca americana (fractions Pa2 and Pa4), lectin fromWistaria floribunda, ovine lutropin, a Bence Jones protein, and histone H2B. While the helix content of lysozyme was raised by SDS slightly, in the Bence Jones protein andW. floribunda lectin it increased from near zero to about 25–30%. In histone H2B the helix content was raised by SDS even to about 48%. However, no clear indication of helix formation could be observed in the mitogens and lutropin, even at low pH or 2.0–2.5. The tertiary structure of the proteins was perturbed by SDS. It was concluded that the reorganization of secondary structure of the proteins was favored by the following factors: (1) presence of helicogenic amino acid sequences in the protein, (2) availability of positively charged sites of the basic amino acids for interactions with the dodecyl ion, (3) absence of a large surplus of negatively charged sites on the surface of protein, and (4) absence of extensive disulfide cross-linking within the macromolecule. Both hydrophobic and electrostatic interactions occur in reconstructive denaturation, and the newly formed helices are stabilized by hydrophobic shielding by the alkyl chains of the alkyl sulfate. 相似文献
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