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Evolution of freezing susceptibility and freezing tolerance in terrestrial arthropods 总被引:2,自引:0,他引:2
Arthropods have evolved various adaptations to survive adverse seasons and it has long been discussed why some arthropods are freezing-susceptible and some are freezing-tolerant. However, which mode of frost resistance came first during the course of evolution? A commonly held opinion is that no choice of strategy has been offered in evolution, because each species of arthropod may have its own evolutionary and natural history, leading to cold-hardiness. Freezing tolerance is more frequent in holometabolous insect orders and partially used by certain vertebrates, like some terrestrially hibernating amphibians and reptiles. Supported by phylogenetic, ontogenetic and ecological arguments, we suggest here that freezing tolerance is more recent than freezing susceptibility in the course of arthropods evolution. In addition, we observe that three basic modes of freezing resistance in insect species exist in the field: (i) permanent or year-round freezing-susceptible species, (ii) alternative or seasonal freezing-susceptible/freezing-tolerant species, (iii) permanent or year-round freezing tolerant species. 相似文献
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Intracellular freezing in biomaterials 总被引:1,自引:0,他引:1
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The recently formulated bioheat equation of Weinbaum and Jiji which accounts for the vascular ultrastructure and blood perfusion was applied to the freezing of peripheral tissue. Using quasi-steady approximation the temperature distribution in the two-phase tissue and the motion of the frozen front were determined. Results are in good agreement with Pennes' bioheat equation. 相似文献
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Thomas DN 《Trends in microbiology》2005,13(3):87-88
Polar deserts are not devoid of life despite the extreme low temperature and scarcity of water. Recently, patterned stone fields--caused by periglacial activity--have been surveyed in the Arctic and Antarctic. It was found that the productivity of the cyanobacteria and algae (hypoliths) that colonise the underside of the stones is strongly related to the pattern of the stones. The hypolith assemblages were in some cases as productive as lichens, bryophytes and plants that resided nearby. 相似文献
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Field ecology of freezing: Linking microhabitat use with freezing tolerance in Litoria ewingii 下载免费PDF全文
A small number of vertebrate species, including some frogs, are freezing tolerant and survive ice forming in their bodies under ecologically relevant conditions. Habitat use information is critical for interpreting laboratory studies of freezing tolerance, but there is often little known about the winter habitat and behaviours of the species under study. This work describes microhabitats used by the freezing‐tolerant frog Litoria ewingii Duméril and Bibron 1841 and their temperature characteristics. In winter, L. ewingii used microhabitats with wood, located further away from water than in summer. Microhabitat temperature records showed that frog microhabitats regularly fell below the temperature at which frog body fluids freeze (?1°C), and cooled substantially more slowly than did the air temperature. Temperatures were highly variable between microhabitats, seasons and years, with a minimum of ?2.4°C and a maximum cooling rate of 0.77°C h?1. Frozen frogs were observed to recover in the field, demonstrating freezing tolerance. Both the characteristics of microhabitats and their selection are important in ensuring freezing survival. 相似文献
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Manipulating freezing tolerance in transgenic plants 总被引:5,自引:0,他引:5
Winterhardiness is a composite of tolerances to freezing, desiccation, ice-encasement, flooding and diseases. From one point
of view, winterhardiness may not be easily manipulated by genetic engineering technology because many different genes are
involved in the tolerance of these diverse stresses. However, these various stresses have similarities. They promote formation
of activated forms of oxygen, promote membrane lipid and protein degradation, cause similar biophysical changes in membrane
structure, and culminate with increased leakage of cytoplasmic solutes and loss of cellular membrane functions. These similarities
led to the hypothesis that winter injury might be reduced in crop plants if their tolerance of oxidative stress was increased.
Towards that objective we created transgenic alfalfa (Medicago sativa L.) plants that overexpress either Mn-SOD or Fe-SOD cDNA (provided by Dirk Inzé, Universiteit Gent). Petiole explants were
transformed using Agrobacterium tumefaciens and plants were regenerated by somatic embryogenesis. The primary transgenic plants were screened using PCR (polymerase chain
reaction), Southern hybridization and native PAGE for SOD activity. Greenhouse and laboratory studies showed a minimal difference
in stress tolerance between the primary transgenic and non-transgenic plants. In the first field trial, four primary transgenic
plants expressing two forms of the Mn-SOD cDNA had greater survival after two winters than the non-transgenic RA3. Similar
results were obtained in a second field trial, comparing 18 independent transformants with Mn-SOD targeted to the mitochondria,
11 independent transformants with Mn-SOD targeted to the chloroplast and 39 independent transformants with Fe-SOD targeted
to the chloroplast, expressed in three different non-transgenic plants. The transgenic plants averaged over 25% higher survival
than the non-transgenic controls after one winter. There was no effect of subcellular targeting or SOD type on field survival,
but there was variation among independent transformants containing the same SOD construct. Activated oxygen therefore appears
to be one of the possible causes of winter injury, and it should be possible to reduce winter injury in transgenic plants
by constitutive overexpression of SOD. 相似文献
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Shosuke Kaku 《Cryobiology》1975,12(2):154-159
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Plasmalemma structure in freezing tolerant unicellular algae 总被引:3,自引:0,他引:3
Summary Electron microscopy of several freezing tolerant species of the algal generaChlamydomonas andChloromonas revealed plasmalemma invaginations which are absent from freezing sensitiveChlamydomonas species. The morphology of these invaginations in freezing tolerant strains is described and compared with similar structures in the yeastSaccharomyces cerevisiae. 相似文献