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111.
The Hackensack Meadowlands District is a large heavily degraded, brackish marsh system in the urbanized northeastern region
of New Jersey, USA. Six study sites were used, three of which were restored (Mill Creek, Skeetkill Creek and Vince Lombardi),
and three others were unrestored (Richard DeKorte Park, Cedar Creek and Kingsland Creek). Highly significant differences were
found with respect to snail abundance and gill parasite abundance. In the three restored sites, significantly more Littoridinops tenuipes were found, and Fundulus heteroclitus had significantly more digenean trematode metacercariae gill infections than at unrestored sites. As habitat quality improves
following restoration, the number of suitable digenean trematode parasite hosts multiplies as substrate for benthic invertebrates
(first intermediate host) increases and usage by other species, such as Fundulus spp. (second intermediate host), is encouraged, which then attracts more wading birds (definitive host). Though the restoration
process enhances trophic complexity, including primary consumers (gastropods), secondary consumers (fish) and tertiary consumers
(wading birds), and ultimately parasite diversity, restoration also helps facilitate parasite life cycles. 相似文献
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113.
H Z Bass N Yamashita L T Clement 《Journal of immunology (Baltimore, Md. : 1950)》1992,149(7):2489-2495
The subpopulations of CD8+ T cells defined by CD45RA Ag expression have been hypothesized to represent cells varying in their relative maturation along a common, activation-dependent differentiation pathway. Previous studies have shown that both the CD8+CD45RA+ and CD8+CD45RA- subsets contain precursor cells capable of developing into alloreactive CTL. In the current study, we have examined the mechanisms involved in the generation of CTL effector cells from these two CD8+ subsets. Purified CD8+CD45RA+ or CD8+CD45RA- cells were stimulated with allogeneic non-T cells, either alone or in the presence of CD4+ Th cells. Although the generation of CTL from CD8+CD45RA- precursor cells consistently required the presence of CD4+ Th cells, cytotoxic effector cells could be generated from CD8+CD45RA+ precursor cells in the absence of CD4+ cells. Several lines of evidence indicated that the helper cell-independent generation of cytotoxic effector cells from CD8+CD45RA+ precursors resulted from the unique ability of this subset to produce and use IL-2 in an autocrine fashion: 1) exogenous IL-2 could replace the effects of CD4+ helper cells for either CD8+ subset; 2) the helper cell-independent functional maturation of CD8+CD45RA+ cells could be blocked by anti-CD25 or anti-IL-2 antibodies; and 3) CD8+CD45RA+ cells produced IL-2 after activation with allogeneic cells. The finding that precursors for helper cell-independent CTL generation are restricted to the CD8+CD45RA+ subset suggests that this capability may vary as a function of the maturation of CD8+ cells. 相似文献
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117.
F Bassé P Gaffet F Rendu A Bienvenüe 《Biochemical and biophysical research communications》1992,189(1):465-471
Spin labeled phospholipid analogs were used to directly study changes in aminophospholipid translocase activity in activated platelets. In thrombin-activated platelets, the translocase activity was slightly stimulated, whereas no vesicle formation or proteolysis of cytoskeletal protein occurred. Ca2+ ionophore A23187-mediated activation produced vesiculation and proteolysis. Additionally, the translocase activity was completely inhibited, probably due to a sharp rise the intracellular Ca2+ concentration, as shown when platelets were activated in the presence of various A23187 and Ca2+ concentrations and by the recovery of the translocase activity when Ca2+ was complexed with EGTA. No translocase activity was found in vesicles. Whereas vesiculation and translocase inhibition can occur independently of proteolysis, this later accentuated the shedding phenomenon. 相似文献
118.
L Ghoda M A Phillips K E Bass C C Wang P Coffino 《The Journal of biological chemistry》1990,265(20):11823-11826
Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis. Mouse ODC is rapidly degraded in mouse cells, whereas ODC within Trypanosoma brucei, a protozoan parasite infesting cattle, is stable. We have expressed cloned ODC genes of both T. brucei and mouse in ODC-deficient Chinese hamster ovary (CHO) cells. The T. brucei enzyme is stable, whereas the mouse ODC similarly expressed in CHO cells is unstable. This shows that the observed difference in intracellular stability is a property of the ODC protein itself, rather than the cellular environment in which it is expressed. A chimeric ODC composed of the amino terminus of trypanosome and the carboxyl terminus of mouse ODC is rapidly degraded in CHO cells, suggesting that peptide sequences in the mouse ODC carboxyl terminus determine its stability. 相似文献
119.
In an electrophoretic survey of lactate dehydrogenase (LDH) isozymes in neotropical cichlid fishes (Perciformes: Cichlidae) several species were discovered in which a cathodal liver-restricted isozyme is expressed along with the highly anodal eye-restricted isozyme (LDH-C4 ) typically encountered in perciform fishes. Biochemical characterization of these two isozymes from the basketmouth cichlid, Acaronia nassa (Heckel), strongly suggested that they were non-orthologous and challenged the accepted view that eye- and liver-restricted LDH isozymes are alternative expressions of the same (LDH-C *) gene. In this study, antiserum raised against cypriniform (goldfish) liver-restricted LDH-C4 failed to cross-react with the basketmouth liver-restricted analogue while effectively titrating the eye-restricted, anodal isozyme and, at higher titres, the LDH-B4 , heart-restricted isozyme from all cichlid species. Anti-serum raised against basketmouth muscle-restricted LDH-A4 failed to titrate any of the eye- and liver-restricted isozymes. These data confirm the orthology of eye- and liver-restricted LDH isozymes in Cypriniform and Perciform fishes as originally proposed, suggest that the liver-restricted isozyme of cichlid fishes is non-orthologous and further raise the question of identity and evolutionary origin of this anomalous LDH activity. 相似文献
120.
B. H. Bass 《BMJ (Clinical research ed.)》1956,1(4980):1406-1407