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Espírito-Santo MM Madeira BG Neves FS Faria ML Fagundes M Fernandes GW 《Annals of botany》2003,91(1):13-19
Patterns of phenological variation and reproductive investment were studied in the dioecious shrub Baccharis dracunculifolia DC (Asteraceae), and possible consequences on survivorship were evaluated. The sex ratio was determined in a natural field population (n = 921) of B. dracunculifolia in Belo Horizonte, Brazil. Fifty-two males and 56 females were sampled at random from this population. During the reproductive season of 1999, inflorescence production, shoot growth and mortality, and xylem water potential were recorded for each individual. The population sex ratio was male-biased (1.27 : 1, P < 0.05), and was associated with a higher mortality of female shoots (38.4 vs. 23.1 %, P < 0.05), and individuals (17.8 vs. 11.5 %, P < 0.1), despite lower water stress in female plants. Flowering phenology also differed between the sexes, with males producing more inflorescences, and earlier, than females. Owing to fruit maturation, the number of inflorescences supported by females was higher than that supported by males later in the reproductive season. This occurred during the dry season, and drought stress may have been responsible for the greater female mortality. Thus, the male-biased sex ratio in this population of B. dracunculifolia is probably due to different reproductive functions of males and females. Intersexual differences in reproductive phenology had consequences for plant demography. 相似文献
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The translational diffusion of bovine rhodopsin, the Ca2+-activated adenosinetriphosphatase of rabbit muscle sarcoplasmic reticulum, and the acetylcholine receptor monomer of Torpedo marmorata has been examined at a high dilution (molar ratios of lipid/protein greater than or equal to 3000/1) in liquid-crystalline phase phospholipid bilayer membranes by using the fluorescence recovery after photobleaching technique. These integral membrane proteins having molecular weights of about 37 000 for rhodopsin, about 100 000 for the adenosinetriphosphatase, and about 250 000 for the acetylcholine receptor were reconstituted into membranes of dimyristoylphosphatidylcholine (rhodopsin and acetylcholine receptor), soybean lipids (acetylcholine receptor), and a total lipid extract of rabbit muscle sarcoplasmic reticulum (adenosinetriphosphatase). The translational diffusion coefficients of all the proteins at 310 K were found to be in the range (1-3) X 10(-8) cm2/s. In consideration of the sizes of the membrane-bound portions of these proteins, this result is in agreement with the weak dependence of the translational diffusion coefficient upon diffusing particle size predicted by continuum fluid hydrodynamic models for the diffusion in membranes [Saffman, P. G., & Delbrück, M. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 3111-3113]. Lipid diffusion was also examined in th same lipid bilayers with the fluorescent lipid derivative N-(7-nitro-2,1,3-benzoxadiazol-4-yl)dimyristoylphosphatidylethanolamine. The translational diffusion coefficient for this lipid derivative was found to be in the range (9-14) X 10(-8) cm2/s at 310 K. In consideration of the dimensions of the lipid molecule, this value for the lipid diffusion coefficient is in agreement with the continuum fluid hydrodynamic model only if a near-complete slip boundary condition is assumed at the bilayer midplane. Alternatively, kinetic diffusion models [Tr?uble, H., & Sackmann. E. (1972) J. Am. Chem. Soc. 94, 4499-4510] may have to be invoked to explain the lipid diffusion behavior. 相似文献
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Andreas Kroh Patrícia Madeira Elisabeth Haring 《Journal of Zoological Systematics and Evolutionary Research》2012,50(2):99-105
The distribution of species is expressed by their occurrence in local faunal lists often compiled by non‐taxonomists. In the case of rare or cryptic species, this can pose a severe limitation on the validity and thus the application of the resulting biodiversity data. Here, we show an example of a shallow‐water echinoid to illustrate problematic distribution data based on misidentification. This species, Arbaciella elegans, was established on the basis of Central African material and later reported from various places in the Mediterranean and the Northern Atlantic. Morphological comparison with the type material casts considerable doubt on the validity of these records. Genetical characterization of material from the Azores clearly shows that the dark Arbaciella phenotype reported to the Mediterranean and north‐east Atlantic in fact represents juveniles of another species, namely Arbacia lixula. 相似文献
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The Eimeria genome projects: a sequence of events 总被引:8,自引:0,他引:8
Shirley MW Ivens A Gruber A Madeira AM Wan KL Dear PH Tomley FM 《Trends in parasitology》2004,20(5):199-201
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Fernandez S Katsuyama AM Kashiwabara AY Madeira AM Durham AM Gruber A 《FEMS microbiology letters》2004,238(1):183-188
This study reports the development and characterization of 151 sequence characterized amplified region (SCAR) markers for the seven Eimeria species that infect the domestic fowl. From this set, 84 markers are species-specific and 67 present partial specificity. The complete nucleotide sequence was derived for all markers, revealing the presence of micro- and minisatellite repetitive units in 22 SCARs, with up to five distinct repeat units being observed per marker. Only 15 markers showed significant hits in similarity searches against public sequence databases, thus confirming their anonymous and non-coding character. Finally, a relational database of the markers (the Eimeria SCARdb) was developed and made available on the Internet, providing a valuable resource of SCAR markers that can be useful for molecular diagnosis, and also for epizootiological, genetic variability and genome mapping studies. 相似文献
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