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Timothy M. Judd 《Journal of Insect Behavior》1994,8(3):343-354
During the waggle dance of the honeybee, the dancer is able to tell her nestmates the distance and direction to a rich food source (Frisch, 1967). Little is known about how waggle dance followers are able to read the waggle dance in the darkness of a hive. Initial observations showed that not all of the bees that appear to be dance followers behave the same. Some bees maneuver themselves behind the dancer, while others do not. The paths of a single dancer, trained to an artificial food source, and her followers were traced during the waggle runs. The success of these dance followers was compared to their position relative to the dancer. The results of this study show that during a waggle run a dance follower must position itself within a 30° arc behind the dancer in order to obtain the dance information. The results suggest that bees are using the position of their own bodies to determine direction. 相似文献
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J. M. Simões † P. J. Fonseca ‡ G. F. Turner § M. C. P. Amorim 《Journal of fish biology》2008,72(10):2689-2694
This study describes a new courtship sound (moan) produced by Pseudotropheus spp. males, not previously reported for cichlids. Moans are short tonal sounds often showing frequency modulation. This sound type is of very low amplitude and is produced when males swim in close proximity to a female, usually before performing more exuberant behavioural exhibitions, such as darting, quivering the body and growling. 相似文献
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Gap junctions (GJs) traverse apposing membranes of neighboring cells to mediate intercellular communication by passive diffusion of signaling molecules. We have shown previously that cells endocytose GJs utilizing the clathrin machinery. Endocytosis generates cytoplasmic double-membrane vesicles termed annular gap junctions or connexosomes. However, the signaling pathways and protein modifications that trigger GJ endocytosis are largely unknown. Treating mouse embryonic stem cell colonies – endogenously expressing the GJ protein connexin43 (Cx43) – with epidermal growth factor (EGF) inhibited intercellular communication by 64% and activated both, MAPK and PKC signaling cascades to phosphorylate Cx43 on serines 262, 279/282, and 368. Upon EGF treatment Cx43 phosphorylation transiently increased up to 4-fold and induced efficient (66.4%) GJ endocytosis as evidenced by a 5.9-fold increase in Cx43/clathrin co-precipitation. 相似文献
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Saffron, a spice derived from the flower of Crocus sativus, is rich in carotenoids. Two main natural carotenoids of saffron, crocin and crocetin, are responsible for its color. Preclinical studies have shown that dietary intake of some carotenoids have potent anti-tumor effects both in vitro and in vivo, suggesting their potential preventive and/or therapeutic roles in several tissues. The reports represent that the use of carotenoids without the potential for conversion to vitamin A may provide further protection and avoid toxicity. The mechanisms underlying cancer chemo-preventive activities of carotenoids include modulation of carcinogen metabolism, regulation of cell growth and cell cycle progression, inhibition of cell proliferation, anti-oxidant activity, immune modulation, enhancement of cell differentiation, stimulation of cell-to-cell gap junction communication, apoptosis and retinoid-dependent signaling. Taken together, different hypotheses for the antitumor actions of saffron and its components have been proposed such as a) the inhibitory effect on cellular DNA and RNA synthesis, but not on protein synthesis; b) the inhibitory effect on free radical chain reactions; c) the metabolic conversion of naturally occurring carotenoids to retinoids; d) the interaction of carotenoids with topoisomerase II, an enzyme involved in cellular DNA-protein interaction. Furthermore, the immunomodulatory activity of saffron was studied on driving toward Th1 and Th2 limbs of the immune system. In this mini-review, we briefly describe biochemical and immunological activities and chemo-preventive properties of saffron and natural carotenoids as an anticancer drug. 相似文献
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John A. Dellinger Michael D. Moths Matthew J. Dellinger Michael P. Ripley 《人类与生态风险评估》2014,20(2):461-478
Although dietary concerns of Laurentian Great Lakes (GL) fish focus on the risk from persistent bioaccumulative toxicant (PBT) contaminants, fish are also an important source of nutrients beneficial to human health such as polyunsaturated fatty acids (e.g., eicosapentanoic acid and docosahexanoic acid). This study presents PBT trend data from the GL tribal fisheries over the past 20 years. PBT contaminants (282 analytes) from fillet portions of lake trout and whitefish were analyzed for trending patterns from 1992 to 2011 and are reported on five of the ATSDR/USEPA Great Lakes biomonitoring legacy contaminants (Hg, ΣDDE, ΣDDT, HCB, mirex, and ΣPCBs), two of the optional biomonitoring PBTs (toxaphene and Σdioxins/furans) and PCB 153 as a specific congener marker. Similar to other recent reports our data indicate that most PBT contaminant concentrations in the GL biota have decreased, which may indicate progress in reducing environmental emissions. Our research confirms that all contaminants demonstrate significant declines except Hg and toxaphene. Both of those remained constant after correcting for known independent factors of age, lipid, and size. These results are potentially encouraging and may provide useful data for the long distance and perhaps global influences of PBTs on the safety of fish consumption. 相似文献