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51.
52.
Peripheral reticulum in chloroplasts of plants differing in CO2 fixation pathways and photorespiration 总被引:1,自引:1,他引:0
Summary The development of peripheral reticulum (PR) in chloroplasts varies in C3 and C4 plants. In general, PR is more extensive in C4 plants, but PR is also seen in the chloroplasts of some C3 plants. Within some C4 plants, PR is seen in the bundle sheath cells which predominantly use the C3 pathway. Thus, PR is not associated directly with the presence of the C4 pathway on a cellular basis. Its predominance in C4 plants must be related to some characteristic other than the method of CO2 fixation. Ultrastructural evidence suggests that PR is associated with the rapid transfer of substances into and out of chloroplasts and from mesophyll to bundle sheath cells.Cooperative investigations of the Department of Agronomy, University of Georgia, Athens, Georgia; Department of Agronomy, University of Florida, Gainesville, Florida; and the Plant Science Research Division, Agricultural Research Service, USDA, Gainesville, Florida. The mention of specific products is for the purpose of clarity and does not imply endorsement by the USDA. Journal Series No. 977 of the Georgia Agricultural Experiment Station, and Journal Series No. 3870 of the Florida Agricultural Experiment Station. 相似文献
53.
Using a pair of congenic strains of mice differing only at the Mls haplotype (Mls locus and closely linked genes), BALB/c (Mls
b
) and BALB.D2-Mls
a
, we have compared the in vitro proliferative responses of M1sb lymphocytes to M1sa antigens presented on either lymph node cells (LNC) or peritoneal adherent cells (PAC). Results showed that M1sa-PAC are stronger stimulators than M1sa-LNC, and furthermore, that the supernatant from M1sa-PAC may be effective in eliciting a lymphocyte proliferative response. The proliferation in response to PAC supernatant is partially due to activation by nonspecific factor(s); however, the response in the presence of M1sa incompatible PAC supernatant is about three times greater than the response obtained in the presence of syngeneic M1sb-PAC supernatant, suggesting an additional stimulation by soluble M1sa antigens. Contrasting with the ability of PAC-supernatant to stimulate a primary proliferative response in vitro, the in vivo immunization of Mlsb mice with M1sa-PAC supernatant abrogates the specific proliferative response in subsequent one-way mixed lymphocyte cultures. This abrogation of the specific response is comparable to that observed after immunization with intact M1sa peritoneal or spleen cells, although in the latter case the anti-H-2 proliferative response is also decreased, regardless of whether the H-2 incompatible stimulating cells express an additional incompatibility for M1sa. The proliferation of untreated, but not of M1sa-immunized BALB/c LNC, is stronger in cultures with DBA/2 stimulating cells (incompatible for M1sa and other non-H-2 antigens) than in cultures with BALBM-Mls
a
cells (incompatible for M1sa alone), and is comparable in intensity to that activated by H-2 incompatibility. We conclude that M1sa antigens are more efficiently recognized by unprimed helper T cells when presented on PAC than when presented on LNC. In the primary proliferative response, the effects of M1sa and other non-H-2 antigens may be cumulative. In vivo immunization against M1sa antigens results in suppression of the specific proliferative response and, to a certain extent, of the nonspecific proliferative response (directed against both H-2 and other non-H-2 antigens). Since M1sa antigens are obtainable in soluble form, their physicochemical purification can now be envisaged. 相似文献
54.
The morphology, cell types, and innervation of the several small papillae (x? = 17) and two larger papillae, which together form a ring just outside the fimbriae surrounding the suctorial disc of adult Geotria australis, have been studied using various histological stains, including silver impregnation, and scanning and transmission electron microscopy. The epithelium of all papillae consists almost entirely of mucigenic cells. The multivillous and oligovillous cells, which are found elsewhere in the lamprey epidermis, were not observed, and Merkel and polyvillous cells are rare. Free nerve endings are common, however, in the basal layers of the epidermis. Unlike the small papillae, the two large papillae contain a core of skeletal muscle and a prominent layer of dermal collagen. In the submucosa of these large papillae, the nerves form a dense, compact layer that contains many large and probably sensory axons. It is suggested that the oral disc papillae of adult G. australis are encapsulated mechanosensory structures that play a role in enabling the animal to locate and attach to a suitable point on host fishes or other surfaces. 相似文献
55.
Harvey Hilliard 《BMJ (Clinical research ed.)》1911,2(2660):1676-1677
56.
57.
58.
59.
A report on the 16th International Caenorhabditis elegans Meeting, Los Angeles, USA, 27 June-1 July 2007. 相似文献
60.
Translational regulation of autoimmune inflammation and lymphoma genesis by programmed cell death 4 总被引:1,自引:0,他引:1
Hilliard A Hilliard B Zheng SJ Sun H Miwa T Song W Göke R Chen YH 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(11):8095-8102
Both inflammatory diseases and cancer are associated with heightened protein translation. However, the mechanisms of translational regulation and the roles of translation factors in these diseases are not clear. Programmed cell death 4 (PDCD4) is a newly described inhibitor of protein translation. To determine the roles of PDCD4 in vivo, we generated PDCD4-deficient mice by gene targeting. We report here that mice deficient in PDCD4 develop spontaneous lymphomas and have a significantly reduced life span. Most tumors are of the B lymphoid origin with frequent metastasis to liver and kidney. However, PDCD4-deficient mice are resistant to inflammatory diseases such as autoimmune encephalomyelitis and diabetes. Mechanistic studies reveal that upon activation, PDCD4-deficient lymphocytes preferentially produce cytokines that promote oncogenesis but inhibit inflammation. These results establish that PDCD4 controls lymphoma genesis and autoimmune inflammation by selectively inhibiting protein translation in the immune system. 相似文献