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101.
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Gammadelta T cell receptors (TCRs), alphabeta TCRs, and antibodies are the three lineages of somatically recombined antigen receptors. The structural basis for ligand recognition is well defined for alphabeta TCR and antibodies but is lacking for gammadelta TCRs. We present the 3.4 A structure of the murine gammadelta TCR G8 bound to its major histocompatibility complex (MHC) class Ib ligand, T22. G8 predominantly uses germline-encoded residues of its delta chain complementarity-determining region 3 (CDR3) loop to bind T22 in an orientation substantially different from that seen in alphabeta TCR/peptide-MHC. That junctionally encoded G8 residues play an ancillary role in binding suggests a fusion of innate and adaptive recognition strategies. 相似文献
103.
A severe incongruity has long existed between the well-known complexity of ancient Maya civilization and the relatively feeble economic base that could be reconstructed for it. Recent fieldwork has ihdicated that much more intensive cultivation patterns were used than was previously thought. Data from the use of synthetic aperture radar in aerial surveys of the southern Maya lowlands suggest that large areas were drained by ancient canals that may have been used for intensive cultivation. Ground checks in several limited areas have confirmed the existence of canals, and excavations and ground surveys have provided valuable comparative information. Taken together, the new data suggest that Late Class period Maya civilization was firmly grounded in large-scale and intensive cultivation of swampy zones. 相似文献
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Microcolonial structures have been harvested from desert rock samples for cultivation and ultrastructural examination. The results indicate that these microcolonial structures are fungi previously unrecognized as inhabitants of desert rocks. 相似文献
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Adams M 《Science (New York, N.Y.)》1973,180(4088):840-842
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Adams T 《Science (New York, N.Y.)》1963,139(3555):609-610
Anterior hypothalamic temperature is reported for the unanesthetized cat resting at an air temperature of 22 degrees to 25 degrees C during the ingestion of cold or warm liquids, and during sleep. Drinking cold (5 degrees C) milk resulted in an immediate depression of hypothalamic temperature and a period of peripheral vasodilation in the ear and forepaw foot and toe pads, followed by a drop in rectal temperature. Drinking warm (body temperature) milk did not bring about these changes. Hypothalamic temperature during sleep is lower by approximately 0.5 degrees C and is characterized by widely varying, slow-frequency oscillations, compared to the higher, more precisely controlled temperature seen when the animal is awake. 相似文献