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951.
Taketeru Tomita Keiichi Sato Kenta Suda Junro Kawauchi Kazuhiro Nakaya 《Journal of morphology》2011,272(5):513-524
Studies of the megamouth shark, one of three planktivorous sharks, can provide information about their evolutionary history. Megamouth shark feeding has never been observed in life animals, but two alternative hypotheses on biomechanics suggest either feeding, i.e., ram feeding or suction feeding. In this study, the second moment of area of the ceratohyal cartilages, which is an indicator of the flexural stiffness of the cartilages, is calculated for 21 species of ram‐ and suction‐feeding sharks using computed tomography. The results indicate that suction‐feeding sharks have ceratohyal cartilages with a larger second moment of area than ram‐feeding sharks. The result also indicates that the ram–suction index, which is an indicator of relative contribution of ram and suction behavior, is also correlated with the second moment of area of the ceratohyal. Considering that large bending stresses are expected to be applied to the ceratohyal cartilage during suction, the larger second moment of area of the ceratohyal of suction‐feeding sharks can be interpreted as an adaptation for suction feeding. Based on the small second moment of area of the ceratohyal cartilage of the megamouth shark, the feeding mode of the megamouth shark is considered to be ram feeding, similar to the planktivorous basking shark. From these results, an evolutionary scenario of feeding mechanics of three species of planktivorous sharks can be suggested. In this scenario, the planktivorous whale shark evolved ram feeding from a benthic suction‐feeding ancestor. Ram feeding in the planktivorous megamouth shark and the basking shark evolved from ram feeding swimming‐type ancestors and that both developed their unique filtering system to capture small‐sized prey. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc. 相似文献
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953.
Akihiko Mochizuki Sankichi Horiuchi Nobuichi Goto Rintaro Nakaya 《Microbiology and immunology》1987,31(8):737-744
The plasmid pNR333 is a kanamycin-resistant, deletion derivative of pNR113 with an extremely high copy number in Escherichia coli and in Proteus mirabilis. In order to determine the usefulness of pNR333 as a replication gene of vector, the genes encoding chloramphenicol acetyltransferase (CAT) and β-galactosidase (β-gal) were cloned individually into both pNR333 and other low-copy-number plasmids. The expression of the cloned genes was compared by measuring the specific activity of each enzyme and the amounts of the proteins produced. A hybrid plasmid pNR333-cat expressed 53 times as much activity of CAT as the low-copy plasmid S-a which had a copy number of four. The lacZ gene cloned in pNR333 produced 17 times as much β-gal as in the low-copy-number plasmid pNR1150. These results suggest that pNR333 is a useful vector plasmid for producing a large amount of polypeptides in E. coli hosts. 相似文献
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956.
Tomohiro Ohgomori Osamu Funatsu Syu-ichi Nakaya Akinori Morita Masahiko Ikekita 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009,1790(12):1611-1623
Intercellular adhesion molecule-5 (ICAM-5, telencephalin) is a dendritically polarized membrane glycoprotein expressed in tissues distinct from those expressing other ICAMs. Here, we determined the N-glycan structure of ICAM-5 purified from adult rat brain and compared it with that of other ICAMs. N-glycans were released by N-glycosidase F digestion and labeled with p-amino benzoic octylester (ABOE). ABOE-labeled glycans were analyzed by high performance liquid chromatography (HPLC) and mass spectrometry. The N-glycans obtained from rat brain ICAM-5 consisted of approximately 85% neutral, 10.2% sialylated-only, 2.8% sulfated-only, and 1.2% sialylated and sulfated glycans. Compared with the N-glycan structures of human ICAM-1 expressed in CHO cells, HEK cells, or mouse myeloma cells and ICAM-3 isolated from human T-cells, rat brain ICAM-5 had less highly branched glycans, sialylated glycans, and N-acetyllactosamine structures. In contrast, high-mannose-type N-glycans and Lewis X were more commonly found in rat brain ICAM-5 than in human ICAM-1 expressed in CHO cells, HEK cells, or mouse myeloma cells and ICAM-3 isolated from human T-cells. In addition, sulfated glycans contained GlcNAc 6-O-sulfate on the non-reducing terminal side. Our data will be important for the elucidation of the roles of the N-glycans expressed in neural cells, including those present on ICAM-5. 相似文献
957.
Plants require substantial resistance against freezing and pathogens for overwintering. These two traits are acquired through
cold acclimation. In contrast to freezing tolerance, molecular basis of disease resistance acquired through cold acclimation
is poorly understood. Recent studies have suggested that pathogenesis-related (PR) proteins that are secreted into the apoplast
during cold acclimation are responsible for the disease resistance. Interestingly, some of the cold-induced PR proteins display
both antifungal and antifreeze activities, suggesting a dual function in protecting plants from overwintering stresses. The
signaling pathway for cold-induced disease resistance is currently unknown but can be independent of pathogen-induced defense
mechanisms. 相似文献
958.