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111.
MARCEL KLAASSEN BEREND HABEKOTTÉ PETER SCHINKELSHOEK ERIC STIENEN PIET VAN TIENEN 《Ibis》1994,136(2):197-204
Time budgets of free-living chicks of Arctic Terns Sterna paradisaea and Common Terns S. hirundo throughout development are presented with special reference to changes in time allocation when growth rate varies. Chicks of both species were inactive most of the time observed (87%). Time allocated to the different behaviours changed during development and was generally better correlated with body mass than age. Slower growing nestlings were brooded more and allocated more time to quiescence and less time to locomotion, preening, begging and attacking (the latter two significant only for the Arctic Tern). The energetic implications of variation in time budgets with age and growth rate were considered. Parental brooding resulted in an average energy saving of nearly 40% of an individual nestling's thermoregulatory costs. Whereas thermoregulatory costs remained nearly unchanged in Arctic Tern chicks, these were negatively correlated with growth rate in Common Terns. Tentatively, we estimated a 30% reduction in a nestling's total energy requirement for a 50% reduction in average growth rate for both species. 相似文献
112.
Comparisons of life-cycles of entoprocts, ectoprocts and phoronidsindicate that the ectoprocts probably have evolved from entoproct-likeancestors, whereas the phoronids are of a quite different type.A review of our knowledge of structure and development of thethree groups lends support to this idea. The Entoprocta andEctoprocta should accordingly be united into the phylum Bryozoa,which is related to the Annelida and Mollusca. The Phoronidaare probably more related to the deuterostomes. 相似文献
113.
Pea stem tissue (Pisum sativum L. var. Alaska) was homogenizedin a recently-developed cytoskeleton-stabilizing buffer, CSB,(Abeand Da vies, 1991) and homogenates electrophoresed and blottedon to membranes. Blots probed individually withantibodies toactin, alpha-tubulin, and beta-tubulin, revealed bands withapparent molecular weights of 42, 46, and 4850 kDa,respectively.Blots probed with all three antibodies simultaneously revealedall three bands which could be distinguished in thesame lane.Homogenates of mouse 3T3 cells yielded an actin band at about42 kDa, but both alpha- and beta-tubulin appeared atabout 50kDa and thus could not be distinguished on blots probed simultaneously.This triple-blotting technique was, therefore,suitablefor pea tissue, but not for mouse tissue. In pea tissue, sedimentabletubulin and actin were found maximally in the 4000 xg pelletand less in successive 15000 and l00000xg pellets. Both EGTAand Mg2+ which had been found earlier to beessential for stabilityof the actin cytoskeleton as revealed by fluorescence microscopy,were essential for co-sedimentation of actinand tubulin. Incontrast to the results with pea stems, only the actin componentof the cytoskeleton could be isolated from mouse 3T3 cells usingCSB. Pea tissue was homogenized in CSB without PTE and the resultingcytoskeletal pellets resuspended in actin- or tubulin-solubilizingbuffers with and without PTE. In the absence of PTE, the bufferssolubilized their appropriate cytoskeletal protein, but littleof the other protein, while in the presence of PTE both proteinswere quite effectively solubilized by both buffers. Incontrast,in CSB with or without PTE, both proteins remained in the sedimentablefraction. These results, taken together withother evidence,indicate that microtubules, as well as microfilaments are importantcomponents of the sedimentable cytoskeletonfraction of peasand that the membrane system is intimately involved in organizationof the cytoskeleton in peas. Key words: Actin, tubulin, membranes, detergent, Ca2+, Mg2+, cytoskeleton 相似文献
114.
Comparative osteology and phylogenetic systematics of fossil and living bony-tongue fishes (Actinopterygii, Teleostei, Osteoglossomorpha) 总被引:2,自引:0,他引:2
ERIC J. HILTON 《Zoological Journal of the Linnean Society》2003,137(1):1-100
Several recent studies using analyses of morphological characters have addressed the interrelationships of Osteoglossomorpha, a group that sometimes is considered the living sister group of all other living teleosts. Many characters used in these studies were found to be poorly defined, to be coded incorrectly or illogically, or to display more variation than was described. The goal of this study is to address these concerns and contribute generally to knowledge of the morphology and systematic relationships of osteoglossomorphs. Analysis of 72 characters (65 informative) scored for 20 genera resulted in two most parsimonious cladograms (171 steps, CI = 0.6433, CI = 0.6139 excluding uninformative characters, HI = 0.3977, HI = 0.3861 excluding uninformative characters; RI = 0.7782; RC = 0.5006). Osteoglossomorpha is supported by both synapomorphies and homoplasies, although its monophyly was not truly tested in this analysis (only a single outgroup, Elops , was included in the analysis). The only difference in the topologies of these cladograms is in the position of ?Lycoptera (recovered as either the sister group of all other osteoglossomorphs sampled or of ?Eohiodon +Hiodon ). ?Ostariostoma is recovered as the sister group of all non‐hiodontiform osteoglossomorphs. Mormyrids are the sister group of notopterids + osteoglossids. This clade has not been found in other recent analyses. Mormyrids and notopterids usually are considered more closely related to each other than to any other group; characters not included here support this relationship and future consideration of these characters must be made. Although almost completely dichotomous, many nodes of the resulting trees lack rigorous support. For example, ?Palaeonotopterus is interpreted as the sister group of all mormyrids sampled, although for this taxon only 22% of characters could be scored. © 2003 The Linnean Society of London. Zoological Journal of the Linnean Society , 2003, 137 , 1?100. 相似文献
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118.
ERIC J. KOLADA JAMES S. SEDINGER MICHAEL L. CASAZZA 《The Journal of wildlife management》2009,73(8):1333-1340
ABSTRACT Loss of nesting habitat is believed to be a factor in the decline of greater sage-grouse (Centrocercus urophasianus) throughout its range. Few data are available for sage-grouse in Mono County, California, USA, in the most southwestern portion of the species’ range. We studied habitat selection of nesting sage-grouse in Mono County, California, from 2003 to 2005 by capturing and radiotracking females to identify nesting locations. We sampled vegetation at nest sites and randomly selected sites within 200 m of nests and within each of 5 subareas within Mono County. Nest sites were characterized by 42.4 ± 1.3% (x̄ ± SE) shrub canopy cover, 10.5 ± 1.0 cm residual grass height, and 2.7 ± 1.0% residual grass cover. Shrub cover was the only variable found to differentiate nest sites from randomly selected sites. Unlike some other studies, we did not find understory vegetation to be important for selecting nest sites. Mean shrub cover was 38.7 ± 1.5% at random sites within 200 m of nests and 33.6 ± 1.6% at random sites at the approximate scale of home ranges, indicating that nesting females selected nesting areas that contained denser shrubs than their home range, and nest sites that contained greater shrub cover than the vicinity immediately surrounding nests. Our results suggest that managers should consider managing for greater shrub cover in Mono County than what is currently called for in other parts of sage-grouse range and that management for sage-grouse habitat may need to be tied more closely to local conditions. 相似文献
119.
Summary. A comparison of the standard E reagents provided clear evidence for the allele Ebdamr (E17 ) in Danish Landrace and wild pigs. 相似文献
120.
Flowering time divergence and genomic rearrangements in resynthesized Brassica polyploids (Brassicaceae) 总被引:5,自引:0,他引:5