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1.
2.
Guaraná (Paullinia cupana) is a woody vine or sprawling shrub native to the central Amazon Basin. The seeds are commercially produced on some 6,000 ha in the state of Amazonas near Manaus. The principal article of commerce is an amber-colored, carbonated soft drink. It is also widely used as a high caffeine stimulant and in local medicines. The plant is monoecious and is damaged by a number of diseases, the most severe being anthracnose. Prospects are excellent for greatly expanded international markets. 相似文献
3.
Critical epitopes in transmissible gastroenteritis virus neutralization. 总被引:23,自引:13,他引:10
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Purified transmissible gastroenteritis (TGE) virus was found to be composed of three major structural proteins having relative molecular weights of 200,000, 48,000, and 28,000. The peplomer glycoprotein was purified by affinity chromatography with the monoclonal antibody (MAb) 1D.G3. A collection of 48 MAbs against TGE virus was developed from which 26, 10, and 3 were specific for proteins E2, N, and E1, respectively. A total of 14 neutralizing MAbs of known reactivity were E2 protein specific. In addition, MAb 1B.C11, of unknown specificity, was also neutralizing. These MAbs reduced the virus titer 10(2)- to 10(9)-fold. Six different epitopes critical in TGE virus neutralization were found, all of which were conformational based on their immunogenicity and antigenicity. Only the epitope defined by MAb 1G.A7 was resistant to sodium dodecyl sulfate treatment, although it was destroyed by incubation in the presence of both the detergent and beta-mercaptoethanol. The frequency of MAb-resistant (mar) mutants selected with four MAbs (1G.A7, 1B.C11, 1G.A6, and 1E.F9) ranged from 10(-6) to 10(-7), whereas the frequency of the putative mar mutant defined by MAb 1B.B11 was lower than 10(-9). Furthermore, the epitopes defined by these MAbs and by MAbs 1H.C2 and 1A.F10, were present in 11 viral isolated with different geographical locations, years of isolation, and passage numbers (with the exception of two epitopes absent or modified in the TOY 56 viral isolate), suggesting that the critical epitopes in TGE virus neutralization were highly conserved. 相似文献
4.
J M Saavedra A Israel F M Correa M Kurihara 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1986,182(4):559-563
Binding sites for rat atrial natriuretic peptide (6-33) (ANP) were quantitated in the subfornical organ of chronically dehydrated homozygous Brattleboro rats unable to synthesize vasopressin; heterozygous Brattleboro rats, their controls, Long Evans rats and Long Evans rats after 4 days of water deprivation. Brain sections were incubated in the presence of 125I-ANP and the results analyzed by autoradiography coupled to computerized microdensitometry and comparison to 125I-standards. Brattleboro rats and water deprived Long Evans rats presented a higher number of ANP binding sites than their normally hydrated controls. Our results suggest a role of ANP binding sites in the subfornical organ in the central regulation of fluid balance and vasopressin secretion. 相似文献
5.
Fully developed thalli of Chondrus crispus, Gracilaria chilensis, Gymnogongrus furcellatus and Mazzaella laminarioides were used to assess tissue compatibility. The effect of thallus polarity on grafting and regeneration was also evaluated. Fusion did occur between fragments of the same life history phase in C. crispus, G. chilensis, G. furcellatus and M. laminarioides. Fusion between sporophytic and gametophytic tissue occurred in C. crispus, G. chilensis and M. laminarioides. Intergeneric fusion was observed between C. crispus and M. laminarioides, but not between G. chilensis and G. furcellatus.Outer cell wall, cortex and medulla were continuous at the contact face in compatible combinations. Medullary cells in the attached fragments were thinner and longer than normal cells, forming an interwoven scar plate. Thallus polarity did not modify fusion and regeneration. 相似文献
6.
This study is the first report of an algal disease, developed in close association with an endophytic organism, documented for the southeastern Pacific. We describe a disease affecting wild populations of the red alga Iridaea laminarioides Bory in central Chile, characterized by gall development on the surface of sporophytic, cystocarpic, and immature thalli. These abnormal growths result in severe morphological alterations of the affected thalli. Diseased fronds display an aggregated spatial distribution and occur throughout the year, with a maximum in summer followed by a decline in winter. The presence of galls was not associated with broken or torn fronds. Although causality has not been unequivocally demonstrated, our field and laboratory observations indicate a strong association of the galls with infections by an endophytic cyanobacterium, probably belonging to the genus Pleurocapsa. 相似文献
7.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
8.
Luis A. Videla Loreto Correa Marcela Rivera Teresa Sir 《Free radical biology & medicine》1993,14(6):669-675
Luminol-amplified CL of whole blood phagocytes was studied in rats given 3 consecutive doses of 0.1 mg L-triiodothyronine T3/kg or in hyperthyroid patients, after stimulation by zymosan. In both cases, CL was significantly increased, in effect which was produced independently of the opsonization of the zymosan particles and markedly inhibited by azide. The in vitro addition of T3 or L-thyroxine (T4) to whole blood phagocytes from normal rats did not modify the opsonized zymosan-dependent CL, when assayed at the concentrations found in eutrhyroid subjects or in hyperthyroid patients. Administrations of propylthiouracil (400 mg/day for 2–3 months) to hyperthyroid patients reduced the CL response observed prior to treatment, to values comparable to those found in the euthyroid group. These data indicate that hyperthyroidism elicits an enhanced respiratory burst activity of whole blood phagocytes, probably related to adaptive changes induced by thyroid hormone on the mieloperoxidase-H2O2 system, rather than to direct actions of the hormone molecule or changes in the opsonic capacity of plasma. 相似文献
9.
Bruno Moises de Matos Marco Augusto Stimamiglio Alejandro Correa Anny Waloski Robert 《World journal of stem cells》2023,15(5):453-465
Extracellular vesicles (EVs) are nanometric particles that enclose cell-derived bioactive molecules in a lipid bilayer and serve as intercellular communication tools. Accordingly, in various biological contexts, EVs are reported to engage in immune modulation, senescence, and cell proliferation and differentiation. Therefore, EVs could be key elements for potential off-the-shelf cell-free therapy. Little has been studied regarding EVs derived from human pluripotent stem cells (hPSC-EVs), even though hPSCs offer good opportunities for induction of tissue regeneration and unlimited proliferative ability. In this review article, we provide an overview of studies using hPSC-EVs, focusing on identifying the conditions in which the cells are cultivated for the isolation of EVs, how they are characterized, and applications already demonstrated. The topics reported in this article highlight the incipient status of the studies in the field and the significance of hPSC-EVs’ prospective applications as PSC-derived cell-free therapy products. 相似文献
10.
Seven strains of Rhizobium loti were tested for acid tolerance in yeast-extract mannitol (YEM) broth at pH values ranging from 4.0 to 8.0. The strains that grew at pH 4.0 showed the slowest generation time when grown at pH above 7.0 and also produced the most acid. The acid tolerance was related to the composition and structure of the membrane. pH influenced protein expression in acid-tolerant strains growing at pH 4.0 or 7.0. Acid tolerant strains showed one membrane protein of 49.5 kDa and three soluble proteins of 66.0, 58.0 and 44.0kDa; their expression increased when the cells grew at pH 4.0. It is suggested that acid tolerance in Rhizobium loti involves constitutive mechanisms, such as permeability of the outer membrane together with adaptive responses, including the state of bacterial growth and concomitant changes in protein expression. 相似文献