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A protein macromolecule in the cytosol of the unicellular eukaryotic yeast Saccharomyces cerevisiae selectively binds the vertebrate estrogen hormone 17 beta-estradiol with high affinity. Lipid extracts of the yeast cells or the conditioned growth medium yield a substance that can bind competitively to the tritiated estradiol-binding sites in the yeast and to mammalian estrogen receptors. These findings suggest that the binding protein may be a primitive hormone receptor and that the lipid-extractable substance represents the endogenous ligand.  相似文献   
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The consumption of wood and wood products in Greece is based greatly on imports necessitating every year a great proportion of public expenditures. The study of wood and wood product imports consequently, is important to the national economy and can be a useful guide for the forest farms, wood industries and wood firms. In this paper the Greek aggregate import demand for Unprocessed wood (such as logs) Processed wood (such as sawn wood), Veneer Crafts (such as veneer sheets) and Wood Manufactures during the period 1969–2001 is empirically analysed using the linear approximation of quadratic AIDS (QUAIDS) model. Imports of Unprocessed wood, Veneer Crafts and Wood Manufactures are found to be price-elastic, in contrast to Processed wood imports. Processed wood, Veneer Crafts and Wood Manufacture imports are found to be expenditure-elastic while Unprocessed wood is found to be an inferior good. Substitution possibilities are found to be significant between Veneer Crafts and all the remaining wood imports and between Processed wood and Unprocessed wood.  相似文献   
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Partially purified lipid extracts of Saccharomyces cerevisiae contain a substance that displaces tritiated estradiol from rat uterine cytosol estrogen receptors. The yeast product induces estrogenic bioresponses in mammalian systems as measured by induction of progesterone receptors in cultured MCF-7 human breast cancer cells and by a uterotrophic response and progesterone receptor induction after administration to ovariectomized mice. The findings raise the possibility that bakers' yeast may be a source of environmental estrogens.  相似文献   
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Cyanobacterial blooms are a major and growing problem for freshwater ecosystems worldwide that increasingly concerns public health, with an average of 60% of blooms known to be toxic. The most studied cyanobacterial toxins belong to a family of cyclic heptapeptide hepatotoxins, called microcystins. The microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cell damage following cellular uptake via organic anion-transporting proteins (OATP). Their intracellular biologic effects presumably involve inhibition of catalytic subunits of protein phosphatases (PP1 and PP2A) and glutathione depletion. The microcystins produced by cyanobacteria pose a serious problem to human health, if they contaminate drinking water or food. These toxins are collectively responsible for human fatalities, as well as continued and widespread poisoning of wild and domestic animals. Although intoxications of aquatic organisms by microcystins have been widely documented for freshwater ecosystems, such poisonings in marine environments have only occasionally been reported. Moreover, these poisonings have been attributed to freshwater cyanobacterial species invading seas of lower salinity (e.g., the Baltic) or to the discharge of freshwater microcystins into the ocean. However, recent data suggest that microcystins are also being produced in the oceans by a number of cosmopolitan marine species, so that Hepatotoxic Seafood Poisoning (HSP) is increasingly recognized as a major health risk that follows consumption of contaminated seafood.  相似文献   
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Three apricot (Prunus armeniaca L.) cultivars were subjected to different degrees of fruit thinning during pit hardening. At harvest fruit quality characteristics were assessed, along with phytochemicals’ concentration, such as carbohydrates, phenolic compounds and organic acids. Antioxidant capacity of the pulp was estimated by diphenyl picryl hydrazyl and ferric reducing antioxidant power assays. Thinning improved fruit weight in two of the three cultivars with a subsequent decrease in fruit firmness, without significant effect on total soluble solid content and titratable acidity. The skin color was not influenced by thinning, but carbohydrate concentration and sweetness index increased. Total phenol concentration increased with thinning, without any similar increase of the major individual phenolic compounds detected (neo-chlorogenic acid, chlorogenic acid, rutin, catechin, epicatechin, ferulic acid, p-coumaric acid and caffeic acid). The antioxidant capacity of the pulp was not influenced by thinning. In overall, thinning enhanced the pomological traits of apricot fruits as well as their phytochemical content.  相似文献   
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Sunspots are regions where strong magnetic fields emerge from the solar interior and where major eruptive events occur. These energetic events can cause power outages, interrupt telecommunication and navigation services, and pose hazards to astronauts. We detected subsurface signatures of emerging sunspot regions before they appeared on the solar disc. Strong acoustic travel-time anomalies of an order of 12 to 16 seconds were detected as deep as 65,000 kilometers. These anomalies were associated with magnetic structures that emerged with an average speed of 0.3 to 0.6 kilometer per second and caused high peaks in the photospheric magnetic flux rate 1 to 2 days after the detection of the anomalies. Thus, synoptic imaging of subsurface magnetic activity may allow anticipation of large sunspot regions before they become visible, improving space weather forecast.  相似文献   
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