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31.
32.
Wing shape has been shown in a variety of species to be influenced by natural and sexual selection. In damselflies, front-
and hind wings can beat independently, and functional differentiation may occur. Males of Calopteryx damselflies show species-specific nuptial flights that differ in colour signalling with the hind wings. Therefore, hind wing
shape and colour may evolve in concert to improve colour display, independent of the front wings. We predicted that male hind
wing shape evolves faster than front wing shape, due to sexual selection. Females do not engage in sexual displays, so we
predicted that females do not show differences in divergence between front- and hind wing shape. We analysed the non-allometric
component of wing shape of five European Calopteryx taxa using geometric morphometrics. We found a higher evolutionary divergence of hind wing shape in both sexes. Indeed, we
found no significant differences in rate of evolution between the sexes, despite clear sex-specific differences in wing shape.
We suggest that evolution of hind wing shape in males is accelerated by sexual selection on pre-copulatory displays and that
this acceleration is reflected in females due to genetic correlations that somehow link the rates of wing shape evolution
in the two sexes, but not the wing shapes themselves. 相似文献
33.
Eelke O. Folmer Matthijs van der Geest Erik Jansen Han Olff T. Michael Anderson Theunis Piersma Jan A. van Gils 《Ecosystems》2012,15(8):1380-1393
The reciprocal effects between sediment texture and seagrass density are assumed to play an important role in the dynamics and stability of intertidal?Ccoastal ecosystems. However, this feedback relationship has been difficult to study empirically on an ecosystem scale, so that knowledge is mainly based on theoretical models and small-scale (experimental) studies. In this paper we apply a non-recursive structural equation model (SEM) to empirically investigate, at large spatial scale, the mutual dependence between seagrass (Zostera noltii) density and sediment texture, on the pristine, seagrass-dominated, intertidal mudflats of the Banc d??Arguin, Mauritania. The non-recursive SEM allows consistent estimation and testing of a direct feedback between sediment and seagrass whilst statistically controlling for the effects of nutrients and abiotic stress. The resulting model is consistent with the hypothesized negative feedback: grain size decreases with seagrass density, whereas fine grain size has a negative impact on seagrass density because it decreases pore water exchange which leads to hypoxic sediment conditions. Another finding is that seagrass density increases with sediment organic material content up to a threshold level beyond which it levels off. In combination with decreasing grain size, accumulation of organic matter creates hypoxic sediment conditions which lead to the production of toxic hydrogen sulfide which slows down seagrass growth. The negative feedback loop implies that intertidal Z. noltii modifies its own environment, thus controlling its growing conditions. To the best of our knowledge, this study is the first to demonstrate a direct negative feedback relationship in ecosystems by means of a non-recursive SEM. 相似文献
34.
Thor Veen M?rten B. Hjernquist Steven L. Van Wilgenburg Keith A. Hobson Eelke Folmer Laura Font Marcel Klaassen 《PloS one》2014,9(5)
Migratory routes and wintering grounds can have important fitness consequences, which can lead to divergent selection on populations or taxa differing in their migratory itinerary. Collared (Ficedula albicollis) and pied (F. hypoleuca) flycatchers breeding in Europe and wintering in different sub-Saharan regions have distinct migratory routes on the eastern and western sides of the Sahara desert, respectively. In an earlier paper, we showed that hybrids of the two species did not incur reduced winter survival, which would be expected if their migration strategy had been a mix of the parent species'' strategies potentially resulting in an intermediate route crossing the Sahara desert to different wintering grounds. Previously, we compared isotope ratios and found no significant difference in stable-nitrogen isotope ratios (δ
15N) in winter-grown feathers between the parental species and hybrids, but stable-carbon isotope ratios (δ
13C) in hybrids significantly clustered only with those of pied flycatchers. We followed up on these findings and additionally analyzed the same feathers for stable-hydrogen isotope ratios (δ
2H) and conducted spatially explicit multi-isotope assignment analyses. The assignment results overlapped with presumed wintering ranges of the two species, highlighting the efficacy of the method. In contrast to earlier findings, hybrids clustered with both parental species, though most strongly with pied flycatcher. 相似文献
35.
36.
Garofalo AW Wone DW Phuc A Audia JE Bales CA Dovey HF Dressen DB Folmer B Goldbach EG Guinn AC Latimer LH Mabry TE Nissen JS Pleiss MA Sohn S Thorsett ED Tung JS Wu J 《Bioorganic & medicinal chemistry letters》2002,12(21):3051-3053
Potent, small molecule A beta inhibitors have been prepared that incorporate an alanine core bracketed by an N-terminal arylacetyl group and various C-terminal amino alcohols. The compounds exhibit stereospecific inhibition as demonstrated in an in vitro assay. 相似文献
37.
Isolation of sertoli cells from adult rat testes: an approach to ex vivo studies of Sertoli cell function 总被引:5,自引:0,他引:5
Much of what is known about the molecular regulation and function of adult Sertoli cells has been inferred from in vitro studies of immature Sertoli cells. However, adult and immature cells differ in significant ways and, moreover, many Sertoli cell functions are regulated by conditions that are difficult to replicate in vitro. Our objective was to develop a procedure to isolate Sertoli cells rapidly and in sufficient number and purity to make it possible to assess Sertoli cell function immediately after the isolation of the cells. The isolation procedure described herein takes less than 4 h and does not require culturing the cells. From a single 4-mo-old adult rat, we routinely obtain 7.0 +/- 0.4 x 10(6) Sertoli cells per testis, and from a 21-mo-old rat, 7.2 +/- 0.4 x 10(6) Sertoli cells per testis. The purity, determined by morphologic analyses of plastic-embedded cells or after staining for tyrosine-tubulin or vimentin, averaged 80%. The contaminants typically included germ cells (10%) and myoid cells (10%). The germ cell-expressed genes protamine-2 and hemiferrin were not detected in the Sertoli cell preparations by Northern blot analyses, but the Sertoli cell-expressed genes clusterin, cathepsin L, and transferrin were highly expressed. Transferrin mRNA levels were greater in Sertoli cells isolated from aged than from young adult rats, consistent with previous analyses of whole testes; and cathepsin L mRNA levels were far more highly expressed in Sertoli cells isolated from stages VI-VII than from other stages of the cycle of the seminiferous epithelium, also consistent with previous analyses of whole testes and isolated tubules. These studies indicate that the freshly isolated cells retain differentiated function, and thus it should be possible to assess the in vivo function of adult Sertoli cells by isolating the Sertoli cells and immediately assessing their function. 相似文献
38.
James E. Lincoln Saskia Folmer Richard M. Bostock David G. Gilchrist 《Plant Molecular Biology Reporter》1998,16(4):367
We have developed a plant transient expression vector that simultaneously expresses -glucuronidase from a Cauliflower mosaic virus promoter, and a test gene from a Figwort mosaic virus promoter. This vector, which is manipulated in E. coli, allows the testing of cell death inducing genes in plant cells. We have demonstrated the capability of this vector by expressing diphtheria toxin. 相似文献
39.
Since early human history, plants have served as the most important source of medicinal natural products, and even in the
“synthetic age” the majority of lead compounds for pharmaceutical development remain of plant origin. In the marine realm,
algae and seagrasses were amongst the first organisms investigated by marine natural products scientists on their quest for
novel pharmaceutical compounds. Forty years after the pioneering work in the field of marine drug discovery began, the biodiversity
of marine organisms investigated as potential sources of anticancer, anti-inflammatory, and antibiotic compounds has increased
tremendously. Nonetheless, marine plants are still an important source of novel secondary metabolites with interesting biomedical
properties. The present review focuses on the antitumour properties of compounds isolated from marine algae, phytoplankton,
mangroves, seagrasses, or cordgrasses. Compounds produced by marine epi- or endophytic fungi are also discussed. 相似文献
40.
Kenyon B Mobley Daniel Lussetti Frank Johansson Göran Englund Folmer Bokma 《BMC evolutionary biology》2011,11(1):1-18