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81.
Managing threatened species: the ecological toolbox, evolutionary theory and declining-population paradigm 总被引:5,自引:2,他引:3
KEN NORRIS 《Journal of Applied Ecology》2004,41(3):413-426
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HIGHTOWER LAWRENCE E.; NORRIS CAROL E.; DIIORIO PHILIP J.; FIELDING EILEEN 《Integrative and comparative biology》1999,39(6):877-888
Over the past twelve years, we have studied heat shock proteinsin two tropical species, a half dozen desert species and a numberof hemiclones of viviparous fishes in the genus Poeciliopsis.Heat shock protein (Hsp) isoform patterns were determined usinghigh resolution two-dimensional polyacrylamide gels. Two familiesof Hsps were studied in detail, the nucleocytoplasmic 70 kilodaltonHsp70 family and the 30 kilodalton Hsp30 family related to -crystallin.The temperature dependence of Hsp accumulation was investigatedusing both intact fish and cultured cells. When the thresholdtemperatures were mapped onto thermal preference profiles, itwas apparent that the Hsp70 threshold (33°C) was closelylinked to the most frequently selected temperatures and theHsp30 threshold (37°C) was closely linked to high temperaturesthat fish rarely selected, indicating that fish deploy thesetwo molecular chaperones differently. One tropical species P.gracilis is a genetic reservoir for most of the Hsp70 isoformsof the desert species. Acquired resistance to 41°C was stronglycorrelated with Hsp70 abundance for gracilis that containedHsp70 isoform 3 whereas fish lacking this isoform showed similarlevels of acquired thermotolerance which did not correlate withHsp70 abundance, suggesting multiple, compensating mechanismsof acquired resistance. Isoform 3 was degraded in cultured cellsfrom a desert species during several hours of recovery at normaltemperature following heat shock whereas two other Hsp70 isoformswere stable. The implications of this property of isoform 3are discussed. 相似文献
84.
Howe GT; Bucciaglia PA; Hackett WP; Furnier GR; Cordonnier-Pratt MM; Gardner G 《Molecular biology and evolution》1998,15(2):160-175
The phytochrome photoreceptors play important roles in the photoperiodic
control of vegetative bud set, growth cessation, dormancy induction, and
cold-hardiness in trees. Interestingly, ecotypic differences in
photoperiodic responses are observed in many temperate- zone tree species.
Northern and southern ecotypes of black cottonwood (Populus trichocarpa
Torr. & Gray), for example, exhibit marked differences in the timing of
short-day-induced bud set and growth cessation, and these responses are
controlled by phytochrome. Therefore, as a first step toward determining
the molecular genetic basis of photoperiodic ecotypes in trees, we
characterized the phytochrome gene (PHY) family in black cottonwood. We
recovered fragments of one PHYA and two PHYB using PCR-based cloning and by
screening a genomic library. Results from Southern analyses confirmed that
black cottonwood has one PHYA locus and two PHYB loci, which we arbitrarily
designated PHYB1 and PHYB2. Phylogenetic analyses which included PHY from
black cottonwood, Arabidopsis thaliana and tomato (Solanum lycopersicum)
suggest that the PHYB/D duplications in these species occurred
independently. When Southern blots were probed with PHYC, PHYE, and PHYE
heterologous probes, the strongest bands that we detected were those of
black cottonwood PHYA and/or PHYB. These results suggest that black
cottonwood lacks members of the PHYC/F and PHYE subfamilies. Although black
cottonwood could contain additional PHY that are distantly related to known
angiosperm PHY, our results imply that the PHY family of black cottonwood
is less complex than that of other well-characterized dicot species such as
Arabidopsis and tomato. Based on Southern analyses of five black cottonwood
genotypes representing three photoperiodic ecotypes, substantial
polymorphism was detected for at least one of the PHYB loci but not for the
PHYA locus. The novel character of the PHY family in black cottonwood, as
well as the differences in polymorphism we observed between the PHYA and
PHYB subfamilies, indicates that a number of fundamental macro- and
microevolutionary questions remain to be answered about the PHY family in
dicots.
相似文献
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D. H. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1990,104(1-3):281-291
Water relations of bryophytes must be understood along at least four dimensions: hydration/dehydration frequency; hydration duration; dehydration duration; degree of water loss. All these are biomass-dependent functions such that large colonies of bryophytes may maintain hydration longer than smaller colonies. The spread of a bryophyte colony allows lateral movement of capillary water; contiguous clones will thus allow lateral conduction of that water. In contrast, separated tufts or cushions may store water but will contribute very little to its transfer over the surface of the phorophyte.
Many of the tropical rainforests of New Guinea have a larger mass of epiphytic bryophytes than any temperate forest. The primary effect of disturbance in these forests is a reduction in bryomass, presumably due to desiccation because of increased insolation and wind movement. The reduction of bryomass will decrease water and mineral retention in the bryophyte clones; and the reduction in the size of those clones will reduce their contiguity and thus interfere with bryophyte-mediatcd water and mineral transfer. Disturbance may alter bryophyte species frequency but, under present agricultural and forestry practices in New Guinea, I have seen no evidence of significant loss of bryophyte species. 相似文献
Many of the tropical rainforests of New Guinea have a larger mass of epiphytic bryophytes than any temperate forest. The primary effect of disturbance in these forests is a reduction in bryomass, presumably due to desiccation because of increased insolation and wind movement. The reduction of bryomass will decrease water and mineral retention in the bryophyte clones; and the reduction in the size of those clones will reduce their contiguity and thus interfere with bryophyte-mediatcd water and mineral transfer. Disturbance may alter bryophyte species frequency but, under present agricultural and forestry practices in New Guinea, I have seen no evidence of significant loss of bryophyte species. 相似文献
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RICHARD E. NORRIS 《The Journal of eukaryotic microbiology》1965,12(4):589-602
SYNOPSIS. Neustonic choanoflagellates can be found in marine tide pools in the San Juan Islands, Washington, and on the Monterey Peninsula, California. Several marine photo-synthetic Chrysophyceae (in the Pedinellaceae), which also occur in these regions, have a basic structure so similar to choanoflagellates that this family is placed in the Craspedomonadales. In pointing out this relationship, the derivation of the Craspedomonadales from pigmented Chrysophyceae is strongly indicated.
In addition to the naked choanoflagellates, which are placed in the Codonosigaceae, these organisms produce loricae of two different types: 1) loricae possibly of cellulose and without visible structure in the light microscope (Salpingoecaceae), 2) loricae composed of silica strands, sometimes forming a mesh with large open spaces (Acanthoecaceae). Members of the latter family seem to be confined to a marine environment and are a prominent part of this investigation. Examination of several species with the electron microscope has revealed interesting details of lorica morphology that are not visible with the light microscope.
Several new combinations of taxa are proposed in addition to new taxa, including 4 new species of Salpingoeca , 3 new species of Diploeca and 4 new species of Pleurasiga. Three new genera are described, Ellisiella gen. nov., Acanthoecopsis gen. nov., and Sportelloeca gen. nov. 相似文献
In addition to the naked choanoflagellates, which are placed in the Codonosigaceae, these organisms produce loricae of two different types: 1) loricae possibly of cellulose and without visible structure in the light microscope (Salpingoecaceae), 2) loricae composed of silica strands, sometimes forming a mesh with large open spaces (Acanthoecaceae). Members of the latter family seem to be confined to a marine environment and are a prominent part of this investigation. Examination of several species with the electron microscope has revealed interesting details of lorica morphology that are not visible with the light microscope.
Several new combinations of taxa are proposed in addition to new taxa, including 4 new species of Salpingoeca , 3 new species of Diploeca and 4 new species of Pleurasiga. Three new genera are described, Ellisiella gen. nov., Acanthoecopsis gen. nov., and Sportelloeca gen. nov. 相似文献
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