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31.
Honeybee dances communicate distances measured by optic flow 总被引:5,自引:0,他引:5
In honeybees, employed foragers recruit unemployed hive mates to food sources by dances from which a human observer can read the distance and direction of the food source. When foragers collect food in a short, narrow tunnel, they dance as if the food source were much farther away. Dancers gauge distance by retinal image flow on the way to their destination. Their visually driven odometer misreads distance because the close tunnel walls increase optic flow. We examined how hive mates interpret these dances. Here we show that recruited bees search outside in the direction of the tunnel at exaggerated distances and not inside the tunnel where the foragers come from. Thus, dances must convey information about the direction of the food source and the total amount of image motion en route to the food source, but they do not convey information about absolute distances. We also found that perceived distances on various outdoor routes from the same hive could be considerably different. Navigational errors are avoided as recruits and dancers tend to fly in the same direction. Reported racial differences in honeybee dances could have arisen merely from differences in the environments in which these bees flew. 相似文献
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The submandibular gland of male mice contained 18% more DNA, 34% more RNA and 63% more protein than that of female mice. After a 48-h fasting, the percent loss of gland weight, protein, RNA and DNA was greater in the female than in the male. 相似文献
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P. S. Subramanian S. Mohanraj P. Kulanthaivel J. Srinivasan 《Cellular and molecular life sciences : CMLS》1977,33(6):707-707
Summary The hitherto unknown lactone of -hydroxy hexacosanoic acid, tetrahydro-6-heneicosyl-2H-pyran-2-one has been isolated from hexane extracts of Heliotropium curassavicum Linn.We are grateful to the University Grants commission, New Delhi for award of Junior Research Fellowships to S.M. and P.K., and to Dr C. C. J. Culvenor, CSIRO (Australia) for the gc-ms data. 相似文献
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Vithana EN Morgan P Sundaresan P Ebenezer ND Tan DT Mohamed MD Anand S Khine KO Venkataraman D Yong VH Salto-Tellez M Venkatraman A Guo K Hemadevi B Srinivasan M Prajna V Khine M Casey JR Inglehearn CF Aung T 《Nature genetics》2006,38(7):755-757
Congenital hereditary endothelial dystrophy (CHED) is a heritable, bilateral corneal dystrophy characterized by corneal opacification and nystagmus. We describe seven different mutations in the SLC4A11 gene in ten families with autosomal recessive CHED. Mutations in SLC4A11, which encodes a membrane-bound sodium-borate cotransporter, cause loss of function of the protein either by blocking its membrane targeting or nonsense-mediated decay. 相似文献
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S. Manivannan P. Dinesh R. Mahemaa Nandhakumaran MariyaPillai S. P. Kumaresh Babu Srinivasan Sundarrajan 《矿物冶金与材料学报》2016,23(10):1196-1203
Mg–8Li–3Al+xCe alloys (x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg–8Li–3Al+xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B–117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg–8Li–3Al (LA83) alloy results in the formation of Al2Ce intermetallic phase, refines both the α-Mg phase and the Mg17Al12 intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce. 相似文献
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Summary Fluoride had no effect on in vitro nitrate reductase activity in rice leaves, but in vivo activity was strongly inhibited. It is suggested that fluoride brings about this inhibition by adversely affecting the physiological NADH generating system required for in vivo nitrate reduction.Acknowledgments. We thank Dr M.S. Naik for useful suggestions and discussion. C.S.R. is grateful to Indian Council of Agricultural Research for a Senior Research Fellowship. 相似文献
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Zusammenfassung Durch Behandlung mit Chloroform ist es möglich,Bacillus popilliae in flüssigem Medium zur Sporenbildung zu veranlassen. Diese Bakterien können zur Bekämpfung von Insekten, derPopilliae japonica, benützt werden. 相似文献
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Conservation of the sequence and temporal expression of let-7 heterochronic regulatory RNA 总被引:72,自引:0,他引:72
Pasquinelli AE Reinhart BJ Slack F Martindale MQ Kuroda MI Maller B Hayward DC Ball EE Degnan B Müller P Spring J Srinivasan A Fishman M Finnerty J Corbo J Levine M Leahy P Davidson E Ruvkun G 《Nature》2000,408(6808):86-89
Two small RNAs regulate the timing of Caenorhabditis elegans development. Transition from the first to the second larval stage fates requires the 22-nucleotide lin-4 RNA, and transition from late larval to adult cell fates requires the 21-nucleotide let-7 RNA. The lin-4 and let-7 RNA genes are not homologous to each other, but are each complementary to sequences in the 3' untranslated regions of a set of protein-coding target genes that are normally negatively regulated by the RNAs. Here we have detected let-7 RNAs of approximately 21 nucleotides in samples from a wide range of animal species, including vertebrate, ascidian, hemichordate, mollusc, annelid and arthropod, but not in RNAs from several cnidarian and poriferan species, Saccharomyces cerevisiae, Escherichia coli or Arabidopsis. We did not detect lin-4 RNA in these species. We found that let-7 temporal regulation is also conserved: let-7 RNA expression is first detected at late larval stages in C. elegans and Drosophila, at 48 hours after fertilization in zebrafish, and in adult stages of annelids and molluscs. The let-7 regulatory RNA may control late temporal transitions during development across animal phylogeny. 相似文献