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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Trees 11 (1996), S. 47-53 
    ISSN: 0931-1890
    Keywords: Key words Frost crack ; Low temperature ; Freezing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In order to determine the timing of the occurrence of frost cracks, as well as to evaluate the climatic conditions associated with such occurrences, study plots were established in late autumn and early winter. Serial observations were made to identify both the occurrence of new frost cracks and the re-opening of old frost cracks in trees in the study plots until mid-winter or early spring. Field observations were conducted for three winter seasons in different study plots. Most old frost cracks were found to re-open in early winter. However, such re-opening did not occur simultaneously within a very limited period of time, for example, within a single day or night, when air temperature fell suddenly or considerably. Re-opening seemed to occur steadily over the course of several days of continuous subzero temperatures. It has been suggested that freezing of the trunk contributes considerably to the re-opening of old frost cracks. Four frost cracks from 1002 trees were newly formed during the course of this study. The new frost cracks developed both in early winter and mid-winter. It has been suggested that new frost cracks can occur during the same period when most old frost cracks re-open and the air temperature does not fall far below 0°C. However, it remains unclear whether or not there is a tendency for new frost cracks to occur during a particular period.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 276 (1978), S. 416-417 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Time course of C2H2-reducing activity in different assay conditions. C2H2-reducing activity was measured by gas chromatography (Shimadzu GC-3BF) with H2-flame ionisation detector. Assay conditions were a 2-cm column containing Porapack Q of 80-100 mesh with N2 gas as carrier at a flow-rate ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 266 (1977), S. 159-161 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Annual shoot growth of Pinus pumila in five stands of the alpine zone of Japan. Values for shoot growth are means of 60-20 plants. The stands are shown in Fig. 2. Correlation coefficient between each two stands: Mt Kisokoma-Mt Norikura, r= 0.396; Mt Kisokoma-Mt Hakusan, r = 0.873; Mt ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 97 (1998), S. 714-720 
    ISSN: 1432-2242
    Keywords: Key words Oryza sativa L. ; Photoperiod-sensitivity genes ; Quantitative traits ; Gene complex ; Wild rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A proposed major quantitative trait locus (QTL) for photoperiod sensitivity on chromosome 6 in rice was examined by introducing a chromosomal segment from a sensitive line into an insensitive one. The crossing experiments showed that a range of variation in heading date occurred in the later generations and that the region might contain at least a major gene and two additional recessive genes controlling photoperiod sensitivity. Gene mapping experiments showed that the major gene was Se-1 and that a recessive gene (tentatively named se-pat) was loosely linked to it. The responses to photoperiods were examined among the different genotypes under natural and controlled conditions. The two genes acted additively on the degree of photoperiod sensitivity. However, se-pat plants showed a response to photoperiods that differed from that of the other sensitive lines; a short-day treatment at the seedling stage delayed heading in the former plants, suggesting that the manner of its expression was age-dependent. A recessive gene similar to se-pat seemed to be widely distributed in wild and cultivated rice, suggesting that the gene complex in the region plays a significant role in response to photoperiod.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1615-6102
    Keywords: Freezing tolerance ; Xylem ray parenchyma cells ; Cell wall ultrastructure ; Supercooling ; Cryo-scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By cryo-scanning electron microscopy we examined the effects of the organization of the cell walls of xylem ray parenchyma cells on freezing behavior, namely, the capacity for supercooling and extracellular freezing, in various softwood species. Distinct differences in organization of the cell wall were associated with differences in freezing behavior. Xylem ray parenchyma cells with thin, unlignified primary walls in the entire region (all cells inSciadopitys verticillata and immature cells inPinus densiflora) or in most of the region (mature cells inP. densiflora and all cells inP. pariflora var.pentaphylla) responded to freezing conditions by extracellular freezing, whereas xylem ray parenchyma cells with thick, lignified primary walls (all cells inCrytomeria japonica) or secondary walls (all cells inLarix leptolepis) in most regions responded to freezing by supercooling. The freezing behavior of xylem ray parenchyma cells inL. leptolepis changed seasonally from supercooling in summer to extracellular freezing in winter, even though no detectable changes in the organization of cell walls were apparent. These results in the examined softwood species indicate that freezing behavior of xylem ray parenchyma cells changes in parallel not only with clear differences in the organization of cell walls but also with subtle sub-electron-microscopic differences, probably, in the structure of the cell wall.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Monoamine ; ZIO reaction ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The reaction of nerve endings in the median eminence of the rat to zinc iodide-osmium tetroxide (ZIO) staining was examined electron microscopically under normal and experimental conditions. The experimental condition of catecholamine exhaustion in the nerve endings was induced by the administration of H44/68 and reserpine. Vesicles in the terminals of catecholaminergic nerves reacted similarly to ZIO staining in both normal and experimental material. The majority of synaptic vesicles in various terminals gave a positive ZIO reaction. The neurosecretory elementary granules, however, failed to react with ZIO. On the other hand, some nerve terminals in the external layer of the median eminence showed a strong positive reaction in the cytoplasmic matrix, in mitochondria as well as in synaptic vesicles. These findings strongly suggest that the ZIO-positive substance in nerve terminals is not the transmitter itself, i.e. the monoamine, but rather represents a range of substances commonly found in various kinds of synaptic vesicles and is probably proteinaceous in nature. A brief discussion is also given on the difference in ZIO reactivity between neurosecretory elementary granules and small vesicles in the hypothalamo-hypophyseal tract.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: LH-RH neurons ; Hypothalamus ; Rat ; Immunohistochemistry ; Radioimmunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The location of the perikarya of LH-RH neurons in the rat hypothalamus and their pathways to the median eminence were studied by immunohistochemistry and radioimmunoassay after placing stereotaxic electrolytic lesions in several parts of the hypothalamus. The principal location of the cell somata was found to be in the ventral part of the medial preoptic area; their pathways were classified into a main baso-lateral pathway and an accessory descending pathway branching off from the former. The main pathway was found to cross in the vicinity of the corresponding neuronal perikarya. The central median eminence and the dorsal and ventral walls of the tubero-infundibular sulcus of the caudal part of the median eminence are innervated mainly by the baso-lateral pathway. On the other hand, the rostral and most caudal portions of the median eminence are innervated principally by the descending pathway and have a subsidiary dual innervation. The projection of LH-RH neurons to the OVLT is believed to originate from perikarya adjacent to this circumventricular organ.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 160 (1975), S. 139-153 
    ISSN: 1432-0878
    Keywords: Arcuate nucleus, cat ; Dense-cored vesicles ; Dopamine ; 5-Hydroxydopamine treatment ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The arcuate nucleus of normal cats and of cats treated with 5-hydroxydopamine (5-OHDA) was investigated by electron microscopy. The neurons of the arcuate nucleus were classified into three types, clear, intermediate and dark, according to their fine structure. The clear type contained numerous dense-cored vesicles and well developed cell organelles. All three types were frequently seen to be partially surrounded by glial processes. Many axo-somatic and axo-dendritic synapses mostly small in diameter were also observed around the neurons. Synaptic contacts were demonstrated between axon endings and axonal processes which contained elementary granules. After administration of 5-OHDA small and large dense-cored vesicles appeared in the nerve endings surrounding the neurons. The relationship between the dense-cored vesicles in the perikarya and dopamine was briefly discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 168 (1976), S. 289-301 
    ISSN: 1432-0878
    Keywords: Arcuate nucleus, cat ; Median eminence ; Dopaminergic tubero ; infundibular tract ; Stereotaxic lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of dopaminergic nerve cells in the cat hypothalamus, particularly in the arcuate and periventricular nuclei, and the projections of their axons were studied by fluorescence and electron microscopy after electrothermic coagulation. The majority of these perikarya were located in the arcuate nucleus and the periventricular nucleus dorsocaudal to the optic chiasma. Large lesions caused a wide and diffuse depletion of dopamine fluorescence within the external layer; small lesions caused ipsilateral partial depletion of the dopamine fluorescence. Electron microscopic observations in animals with a lesioned arcuate nucleus revealed that in the external layer degenerating nerve terminals are engulfed by glial processes. In some cases nerve fibers had entirely disappeared and a heavy reactive proliferation of glial processes was observed. Persistence of the form of the median eminence in spite of the extensive degeneration of its nervous elements is considered to depend upon this glial proliferation.
    Type of Medium: Electronic Resource
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