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Big, beautiful organisms are useful for biological education, increasing evolution literacy, and biodiversity conservation. But if educators gloss over the ubiquity of streamlined and miniaturized organisms, they unwittingly leave students and the public vulnerable to the idea that the primary evolutionary plot of every metazoan lineage is “progressive” and "favors" complexity. We show that simple, small, and intriguingly repulsive invertebrate animals provide a counterpoint to misconceptions about evolution. Our examples can be immediately deployed in biology courses and outreach. This context emphasizes that chordates are not the pinnacle of evolution. Rather, in the evolution of animals, miniaturization, trait loss, and lack of perfection are at least as frequent as their opposites. Teaching about invertebrate animals in a “tree thinking” context uproots evolution misconceptions (for students and the public alike), provides a mental scaffold for understanding all animals, and helps to cultivate future ambassadors and experts on these little‐known, weird, and fascinating taxa. 相似文献
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Jyri Seppla Matti Melanen Ilmo Menp Sirkka Koskela Jyrki Tenhunen Marja‐Riitta Hiltunen 《Journal of Industrial Ecology》2005,9(4):117-130
The concept of eco-efficiency is commonly referred to as a business link to sustainable development. In this article, ecoefficiency is examined at a regional level as an approach to promoting the competitiveness of economic activities in the Finnish Kymenlaakso region and mitigating their harmful impacts on the environment. The aim is to develop appropriate indicators for monitoring changes in the eco-efficiency of the region. A starting point is to produce indicators for the environmental and economic dimensions of regional development and use them for measuring regional eco-efficiency. The environmental impact indicators are based on a life-cycle assessment method, producing different types of environmental impact indicators: pressure indicators (e.g., emissions of CO2 ), impact category indicators (e.g., CO2 equivalents in the case of climate change), and a total impact indicator (aggregating different impact category indicator results into a single value). Environmental impact indicators based on direct material input, total material input, and total material requirement of the Kymenlaakso region are also assessed. The economic indicators used are the gross domestic product, the value added, and the output of the main economic sectors of Kymenlaakso. In the eco-efficiency assessment, the economic and environmental impact indicators are monitored in the same graph. In a few cases eco-efficiency ratios can also be calculated (the economic indicators are divided by the environmental indicators). Output (= value added + intermediate consumption) is used as an economic indicator related to the environmental impact indicators, which also cover the upstream processes of the region's activities. In the article, we also discuss the strengths and weaknesses of using the different environmental impact indicators. 相似文献
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This scanning-electron microscopic study demonstrates the convergent evolution of the mouthparts of various herbivorous stream animals (insects from different orders, an isopod, snails, fish, and a tadpole) feeding on epilithic algal pastures. This food source is rich but is often difficult to harvest. Nevertheless, a large number of species can live on it because they have evolved highly specialized mouthparts. There are four functional problems that an algae grazer has to solve: the algae must be removed from the stone, they have to be collected and crushed, and a current shield is needed to prevent the water flow sweeping away the food. Among the 30 algae grazers examined in this study, a limited number of morphological solutions have been found for each of these adaptational problems. There are multiple evolutionary pathways for mouthpart adaptation and even closely related species have often evolved different types of tools for the same function. This refects the existence of a certain amount of evolutionary scope. Such freedom of evolution is present, however, only at the beginning of the adaptiogenesis of an algae grazer. Once one of the evolutionary pathways is taken, further improvement of the mouthparts is possible only by the refinement of the ‘chosen’ type of tools. The consequence of this is that a large number of astonishing convergences have occurred in algae grazers that have independently trodden the same evolutionary pathway. 相似文献
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Nina Safar-Hermann Mohammed N. Ismail Han Sun Choi Erich Mstl Elmar Bamberg 《Zoo biology》1987,6(2):189-193
Estrogen concentration in feces was investigated in five different herbivorous species of zoo animals. Using a nonspecific estrogen radioimmunoassay, in four species (red buffalo, yak, Grevy's zebra, and Nubian ibex) pregnancy was revealed by measuring estrogen concentration in feces. In hippopotamus, the levels of fecal estrogens were not different between pregnant and nonpregnant animals. 相似文献
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Dr. Rüdiger Gerstberger 《Cell and tissue research》1988,252(1):39-48
Summary In saltwater-acclimated ducks with fully specialized supraorbital salt glands, intracarotid application of acetylcholine (5 nmoles/min/kg b.w.) or porcine vasoactive intestinal polypeptide (pVIP) (240 pmoles/min/kg b.w.) induced secretion from the salt glands at threshold conditions of secretory activity. pVIP-like immunoreactivity could be localized in fibers of the postganglionic secretory nerve ramifying throughout the glandular parenchyma. Both middle-sized arterioles and secretory tubules were innervated, and pVIP-immunoreactive varicose fibers formed peritubular baskets around the basal region of secretory tubules indicating direct innervation of the secretory tissue. pVIP-specific staining could be abolished by preabsorption of the antiserum with peptide extracts of salt-gland tissue. Synthetic pVIP and endogenous VIP from salt glands of the duck co-eluted on the HPLC system, suggesting structural similarity of the peptides. Membrane-binding studies with radioiodinated pVIP revealed the presence of high-affinity binding sites in salt-gland tissue. Affinities of unlabeled pVIP analogues to compete for these binding sites were as follows: pVIP > PHI > pVIP antagonist > secretin > pVIP (10–28) > chicken VIP (16–28). Peptide extracts of salt glands had affinities similar to pVIP. Binding sites could be localized mainly at the apical end of the radially arranged secretory tubules, as demonstrated by receptor autoradiography.It is concluded that, in addition to the classical parasympathetic transmitter acetycholine, VIP serves as neuromodulator/transmitter in cranial parasympathetic control of avian salt-gland secretion by acting on both the arteriolar network and the secretory tubules of the gland. 相似文献
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转铁蛋白结构与功能的研究——骆驼血清转铁蛋自的分离纯化及其含单一铁结合部位的结构域的制备和鉴定 总被引:1,自引:0,他引:1
分离纯化获得的骆驼血清转铁蛋白由分子量为73,000和63,000两个组分组成。两者至少N-端五肽顺序相同(Met-Pro-Asp-Lys-Thr)。骆驼血清转铁蛋白在生理pH下不能与人胎盘转铁蛋白受体结合。用胰蛋白酶酶解骆驼转铁蛋白可以同时得到两个合单一铁结合部位的结构域,分别来自转铁蛋白分子的N-端称N-端结构域(分子量34,700和40,700)和C-端称C-端结构域(分子量35,100)。在上述结果的基础上指出并讨论了反刍动物转铁蛋白在结构和功能上存在更多的共同性,而与其它哺乳动物的转铁蛋白有着明显的区别。 相似文献
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The feasibility of introducing foreign genes into the genomes of cattle, goats, pigs, and sheep has only recently been demonstrated. Studies have thus far focused on improving growth efficiency or directing expression of pharmaceutical proteins to the mammary glands of these species. The general strategy for producing transgenic livestock and mice is similar. In addition to the obvious difference in scale between mice and livestock experiments, there are noteworthy obstacles that significantly reduce the efficiency of producing transgenic livestock. Low embryo viability, low transgene integration rates, and high animal costs contribute to project costs that can easily exceed hundreds of thousands of dollars. A better understanding of the mechanisms that govern transgene integration should lead to improved efficiencies. But, the full potential of the transgenic livestock system will not be fully realized until: 1) gene constructs can be designed that function in a reproducible, predictable manner; and 2) the genetic control of physiological processes are more clearly elucidated. Newly emerging approaches may resolve at least some of these issues within the next decade. 相似文献