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K. Bartoszewicz W. Bielawski G. Garbaczewska J. Kączkowski 《Acta Physiologiae Plantarum》1997,19(3):295-302
The β-endoglucanase is one of the enzymes taking part in the degradation of the cell wall structural polysaccharides. The
use of two Triticale varieties differing in their resistance to the preharvest sprouting allowed the comparison of that enzyme
activity and changes in the internal structure of the cell wall observed in the light and electron microscope. The most interesting
observations seem to be the channels and even the holes in the walls of aleurone cells found mostly in the samples showing
the elevated activities of β-endoglucanase. As those samples concern the grains of a lower resistance to pre-harvest sprouting,
it might be suggested that the loosening of the wall structure may be one of the probable mechanisms in facilitating the enzyme,
metabolite and water translocations through the grain tissues. Those changes can accelerate the water imput into the grain,
the metabolic process and thus the increased susceptibility to sprouting. 相似文献
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Physiological ageing of potato tubers: A Review 总被引:1,自引:0,他引:1
WARREN K COLEMAN 《The Annals of applied biology》2000,137(2):189-199
Numerous theories have been proposed to describe the complex process of ageing in biological systems. Two general groups of ageing theories currently exist: 1) stochastic where the accumulation of random molecular damage leads to loss of information vital to the cell; and, 2) systemic where an organised, genetically based sequence of metabolic activities leads to programmed ageing. Whether these are acceptable models of ageing in potato tubers is unknown although the tuber could provide a useful experimental system for studying ageing. An initial requirement for advancing the concept of ageing in potato tubers must centre on the development of a suitable ageing index. A review of the literature suggests that a modified approach to ‘sprouting capacity’ and ‘incubation period’ may allow tuber ageing to be described in mathematical terms that would, in turn, facilitate the development of a physiological ageing index as well as temperature sensitive predictive models. Although a number of biochemical studies of ageing have been pursued, the development of adequate biomarkers has yet to achieve a coordinated level of development as found in a range of organisms. For example, ageing in other biological systems may be viewed as an outcome of an accumulation of random molecular damage and may be primarily caused by a changing balance between reactive oxygen species and diminishing levels of protective agents such as superoxide dismutase, alpha‐tocopherol or vitamin C. The exploration of these and similar problems in the context of appropriate modelling approaches should allow a better understanding of physiological ageing in potato tubers. 相似文献
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Dr. Yuri V. Panchin Pavel V. Zelenin Lyudmila B. Popova 《Invertebrate neuroscience : IN》1997,3(1):27-40
The neural network underlying rhythmic wing movements in the molluscClione limacina is well-studied. Two different groups of motoneurons innervate two distinct groups of wing muscles. The locomotor rhythm
generated in the left and right pedal ganglia is synchronized by interneurons. When the axons of the locomotor motoneurons
are crushed, numerous fine neurites sprout towards the denervated muscles and reach them in 8–15 days. At this stage motoneurons
project to and synapse on not only correct but equally incorrect muscle targets. After 2 weeks of regeneration the number
of incorrect neurites and synaptic connections begins to decrease and following 1.5–2 months all incorrect connections are
eliminated, incorrect axons are withdrawn and the behavioral deficit is compensated. In this study the regeneration of interneurons
and the growth profiles of inter- and motoneurons were also studiedin vitro. Two individually isolated pedal ganglia were co-cultured in three different configurations: a) the wing nerve stump from
one ganglion was fixed against the commissural stump from another ganglion; b) the wing nerve stumps were fixed against each
other; c) the commissural stumps were fixed against each other. Under the above experimental conditions we found that the
interneurons were able to cross only the contact between two commissural stumps, and in this case found their original targets,
restored correct connections and synchronized the rhythm in two pedal ganglia. In contrast, motoneurons were able to cross
all types of contacts. 相似文献