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61.
Climate-based models of spatial patterns of species richness in Egypt's butterfly and mammal fauna 总被引:1,自引:0,他引:1
Tim Newbold Francis Gilbert Samy Zalat Ahmed El-Gabbas Tom Reader 《Journal of Biogeography》2009,36(11):2085-2095
Aim Identifying areas of high species richness is an important goal of conservation biogeography. In this study we compared alternative methods for generating climate-based estimates of spatial patterns of butterfly and mammal species richness.
Location Egypt.
Methods Data on the occurrence of butterflies and mammals in Egypt were taken from an electronic database compiled from museum records and the literature. Using M axent , species distribution models were built with these data and with variables describing climate and habitat. Species richness predictions were made by summing distribution models for individual species and by modelling observed species richness directly using the same environmental variables.
Results Estimates of species richness from both methods correlated positively with each other and with observed species richness. Protected areas had higher species richness (both predicted and actual) than unprotected areas.
Main conclusions Our results suggest that climate-based models of species richness could provide a rapid method for selecting potential areas for protection and thus have important implications for biodiversity conservation. 相似文献
Location Egypt.
Methods Data on the occurrence of butterflies and mammals in Egypt were taken from an electronic database compiled from museum records and the literature. Using M axent , species distribution models were built with these data and with variables describing climate and habitat. Species richness predictions were made by summing distribution models for individual species and by modelling observed species richness directly using the same environmental variables.
Results Estimates of species richness from both methods correlated positively with each other and with observed species richness. Protected areas had higher species richness (both predicted and actual) than unprotected areas.
Main conclusions Our results suggest that climate-based models of species richness could provide a rapid method for selecting potential areas for protection and thus have important implications for biodiversity conservation. 相似文献
62.
Emilie Knight Emma Greer Tracie Draeger Vera Thole Steve Reader Peter Shaw Graham Moore 《Functional & integrative genomics》2010,10(4):603-608
At the onset of meiosis, chromosomes first decondense and then condense as the process of recognition and intimate pairing
occurs between homologous chromosomes. We show here that okadaic acid, a drug known to induce chromosome condensation, can
be introduced into wheat interspecific hybrids prior to meiosis to induce chromosome pairing. This pairing occurs in the presence
of the Ph1 locus, which usually suppresses pairing of related chromosomes and which we show here delays condensation. Thus the timing
of chromosome condensation during the onset of meiosis is an important factor in controlling chromosome pairing. 相似文献
63.
64.
Margaret E. McCormick Mauricio Rojas Tyler Moser-Katz Ellie Tzima John S. Reader 《PloS one》2014,9(10)
A naturally-occurring fragment of tyrosyl-tRNA synthetase (TyrRS) has been shown in higher eukaryotes to ‘moonlight’ as a pro-angiogenic cytokine in addition to its primary role in protein translation. Pro-angiogenic cytokines have previously been proposed to be promising therapeutic mechanisms for the treatment of myocardial infarction. Here, we show that systemic delivery of the natural fragment of TyRS, mini-TyrRS, improves heart function in mice after myocardial infarction. This improvement is associated with reduced formation of scar tissue, increased angiogenesis of cardiac capillaries, recruitment of c-kitpos cells and proliferation of myocardial fibroblasts. This work demonstrates that mini-TyrRS has beneficial effects on cardiac repair and regeneration and offers support for the notion that elucidation of the ever expanding repertoire of noncanonical functions of aminoacyl tRNA synthetases offers unique opportunities for development of novel therapeutics. 相似文献
65.
Salivary gland duct ligation is an alternative to gland excision for treating sialorrhea or reducing salivary gland size prior to tumor excision. Duct ligation also is used as an approach to study salivary gland aging, regeneration, radiotherapy, sialolithiasis and sialadenitis. Reports conflict about the contribution of each salivary cell population to gland size reduction after ductal ligation. Certain cell populations, especially acini, reportedly undergo atrophy, apoptosis and proliferation during reduction of gland size. Acini also have been reported to de-differentiate into ducts. These contradictory results have been attributed to different animal or salivary gland models, or to methods of ligation. We report here a bilateral double ligature technique for rabbit parotid glands with histologic observations at 1, 7, 14, 30, 60 days after ligation. A large battery of special stains and immunohistochemical procedures was employed to define the cell populations. Four stages with overlapping features were observed that led to progressive shutdown of gland activities: 1) marked atrophy of the acinar cells occurred by 14 days, 2) response to and removal of the secretory material trapped in the acinar and ductal lumens mainly between 30 and 60 days, 3) reduction in the number of parenchymal (mostly acinar) cells by apoptosis that occurred mainly between 14–30 days, and 4) maintenance of steady-state at 60 days with a low rate of fluid, protein, and glycoprotein secretion, which greatly decreased the number of leukocytes engaged in the removal of the luminal contents. The main post- ligation characteristics were dilation of ductal and acinar lumens, massive transient infiltration of mostly heterophils (rabbit polymorphonuclear leukocytes), acinar atrophy, and apoptosis of both acinar and ductal cells. Proliferation was uncommon except in the larger ducts. By 30 days, the distribution of myoepithelial cells had spread from exclusively investing the intercalated ducts pre-ligation to surrounding a majority of the residual duct-like structures, many of which clearly were atrophic acini. Thus, both atrophy and apoptosis made major contributions to the post-ligation reduction in gland size. Structures also occurred with both ductal and acinar markers that suggested acini differentiating into ducts. Overall, the reaction to duct ligation proceeded at a considerably slower pace in the rabbit parotid glands than has been reported for the salivary glands of the rat. 相似文献
66.
Fossil plants from the lower part of Xianshuihe Formation in the Lanzhou Basin, Gansu
Province were studied. The flora contains 29 species, representing 20 genera and 12 families, which
include Lauraceae ( Daphnogene ), Lardizabalaceae ( Akebia ), Berberidaceae ( Berberis ), Ulmaceae
( Planera, Ulmus, Zelkova ), Betulaceae ( Alnus, Carpinus ), Myricaceae( Myrica ), Salicaceae
( Populus, Salix), Myrsinaceae(Ardisia), Rosaceae ( Prunus, Sorbus, Sorbaria, Spiraea ), Leguminosae ( Gleditsia, Sophora), Anacardiaceae (Rhus), Caprifoliaceae(Viburnum). An analysis
of the floristic elements and their foliar physiognomy shows that most members of the flora are deciduous broad-leaved trees or shrubs with a few evergreen shrubs. The most noteworthy species is Rhus
turcomanica which was present in the Middle Eocene to Late Eocene of Central Asia (Kazakhstan,
Turkmenistan). Generally, Rhus turcomanica occurred at the same beds as Palibinia, an extinct
fossil plant whose presence indicates a subtropical dry climate. Another species, Sorbaria callicomifolia Kornilova was present from the Early Oligocene to Early Miocene of Central Asia (Kazakhstan
and Turkmenistan). According to an analysis of spores and pollen, this flora contains over 20 species. It is predominated by the angiosperm pollen. There appeared Ephedripites and Nitrariadites
which were important elements in the dry area. Ephedripites was found from the Upper Cretaceous to
Early Tertiary. Nitrariadites occurred in the Late Miocene, whereas Rhus turcomanica and Sorbaria
callicomifolia were both reported in the subtropical dry area from the Middle Eocene to Early Oligocene. The latest record of Rhus turcomanica is from the Middle Eocene to Early Oligocene of Central
Asia. The presence of this element in the lower part of Xianshuihe Formation may indicate that itsage is the latest stage of the Early Oligocene. 相似文献
67.
Adam N. Keen Luke A. Payne Vedanta Mehta Alistair Rice Lisa J. Simpson Kar Lai Pang Armando del Rio Hernandez John S. Reader Ellie Tzima 《The Journal of cell biology》2022,221(2)
The repertoire of extratranslational functions of components of the protein synthesis apparatus is expanding to include control of key cell signaling networks. However, very little is known about noncanonical functions of members of the protein synthesis machinery in regulating cellular mechanics. We demonstrate that the eukaryotic initiation factor 6 (eIF6) modulates cellular mechanobiology. eIF6-depleted endothelial cells, under basal conditions, exhibit unchanged nascent protein synthesis, polysome profiles, and cytoskeleton protein expression, with minimal effects on ribosomal biogenesis. In contrast, using traction force and atomic force microscopy, we show that loss of eIF6 leads to reduced stiffness and force generation accompanied by cytoskeletal and focal adhesion defects. Mechanistically, we show that eIF6 is required for the correct spatial mechanoactivation of ERK1/2 via stabilization of an eIF6–RACK1–ERK1/2–FAK mechanocomplex, which is necessary for force-induced remodeling. These results reveal an extratranslational function for eIF6 and a novel paradigm for how mechanotransduction, the cellular cytoskeleton, and protein translation constituents are linked. 相似文献
68.
Frances Reader 《BMJ (Clinical research ed.)》1984,288(6432):1762-1763
69.
Summary In this review I offer a solution to the problem why endotherm populations appear to be so inefficient in converting food energy into body substance despite the fact that individual endotherms are just as efficient in this respect as individual ectotherms. Calculated for individuals of half the adult mass both ectotherms and endotherms convert about the same proportion of food energy into somatic growth although for a given body mass the latter expend about 10 times more aerobic power than the former. On the other hand, early in life, during the period of maximum growth, ectotherms channel a 2–3 times greater percentage of metabolic energy into growth than endotherms. Even greater becomes the difference between these two groups if we consider the relative cost of reproduction. It can be shown that, weight by weight, nematodes, fish, birds and mammals require almost the same amount of energy for the production of offspring-, roughly 250 kJ per day and kg of eggs, hatchlings or litter. However, whereas the cost of producing offspring represents only 2%–6% of the total metabolizable energy of an endotherm, a fish has to spend 35%, a nematode nearly everything it has for this purpose. This may explain the finding by Humphreys (1979) and others that in nature the production, efficiencies of endotherm populations appear to be at least one order of magnitude lower than those of ectotherm populations. However, rather than calling endotherms less efficient energy converters, I suggest that by increasing total metabolic power more than ten-fold but keeping the energy cost of reproduction constant, this group of animals achieved emancipation from the burden of reproduction. Conversely, ectotherms have to channel a much greater proportion of metabolic power into reproduction because only in this way are they able to fit their low-rate life cycle schedules into the ecological schedules of the environment. 相似文献
70.
Emmanuel K. Nénonéné Fatiha Radja Martin Carli Nico M. van Gelder Soheila Afkhami-Dastjerdian Tomás A. Reader 《Neurochemical research》1996,21(2):167-176
The binding of tritiated 8-hydroxy-2-(di-n-propyl-amino)tetralin, or [3H]8-OH-DPAT, to membranes from rat cerebral cortex and hippocampus could be inhibited by serotonin (5-HT) and buspirone, and
by the 5-HT antagonists propranolol, NAN-190, pindolol, pindobind-5-HT1A, WAY100135, spiperone and ritanserin. All competition curves, except for ritanserin, best fitted a two-site model. In vitro
treatment of the membranes withN-ethylmaleimide (NEM), to alkylate sulfhydryl groups, caused dose-dependent decreases of binding; the inhibition curves were
biphasic, and the effects irreversible. Reduction of disulfide bonds withl-dithiothreitol (L-DTT) also decreased binding, but in a monophasic way; these effects were fully reversible in cortex, but only partially reversible
in hippocampus. In the latter region, but not in cerebral cortex, previous occupancy by [3H]8-OH-DPAT partially protected binding from the effects of bothL-DTT and NEM, suggesting that the thiol groups in the receptor recognition site(s) of this brain region are readily accessible.
The binding characteristics were examined with the aid of saturation curves, carried out with increasing concentrations, up
to 140 nM, of [3H]8-OH-DPAT. The saturation data were suggestive of a two-site receptor model incorporating a high-affinity site (Kh of 0.3–0.5 nM) corresponding to the 5-HT1A receptor, and a low-affinity site (Kl ofca 25 nM). After in vivo alkylations, carried out by treating rats withN-ethoxycarbonyl-2-ethoxy-1,2-dihydro-quinoline (EEDQ), the saturation curves from both control and EEDQ-treated rats were
again best fitted to a two-site model. For EEDQ-treated animals, a drastic decrease of 5-HT1A receptor activity was noted; this loss was greater in hippocampus than in cerebral cortex. Since the decrease in 5-HT1A receptors was not associated with changes in low-affinity binding, the results suggest independent regulations of the two
[3H]8-OH-DPAT binding proteins. Altogether, the present data further supports the notion that [3H]8-OH-DPAT, besides labelling 5-HT1A receptors, also binds to other structures in rat cerebral cortex and hippocampus.
Special issue dedicated to Dr. Kinya Kuriyama 相似文献