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61.
Ueda T Brenner S Malech HL Langemeijer SM Perl S Kirby M Phang OA Krouse AE Donahue RE Kang EM Tisdale JF 《The Journal of biological chemistry》2005,280(2):991-998
Hematopoietic cells can be highly enriched for repopulating ability based upon the efflux of the fluorescent Hoechst 33342 dye by sorting for SP (side population) cells, a phenotype attributed to expression of ABCG2, a member of the ABC transporter superfamily. Intriguingly, murine studies suggest that forced ABCG2 expression prevents hematopoietic differentiation. We cloned the full-length rhesus ABCG2 and introduced it into a retroviral vector. ABCG2-transduced human peripheral blood progenitor cells (PBPCs) acquired the SP phenotype but showed significantly reduced growth compared with control. Two rhesus macaques received autologous PBPCs split for transduction with the ABCG2 or control vectors. Marking levels were similar between fractions with no discrepancy between bone marrow and peripheral blood marking. Analysis for the SP phenotype among bone marrow and mature blood populations confirmed ABCG2 expression at levels predicted by vector copy number long term, demonstrating no block to differentiation in the large animal. In vitro studies showed selective protection against mitoxantrone among ABCG2-transduced rhesus PBPCs. Our results confirm the existence of rhesus ABCG2, establish its importance in conferring the SP phenotype, suggest no detrimental effect of its overexpression upon differentiation in vivo, and imply a potential role for its overexpression as an in vivo selection strategy for gene therapy applications. 相似文献
62.
Increased expression of prostaglandin endoperoxide H synthase-2 (PGHS-2) has been implicated in pathological conditions such as inflammatory bowel diseases and colon cancer. Recently, it has been demonstrated that inducible nitric oxide synthase (NOS II) expression and nitric oxide (NO) production are up-regulated in these diseases as well. However, the apparent link between PGHS-2 and NOS II has not been thoroughly investigated in nontransformed and nontumorigenic colonic epithelial cells. In the present study, we examined the concomitant expression of PGHS-2 and NOS II as well as the production of prostaglandin E2 (PGE2) and NO in conditionally immortalized mouse colonic epithelial cells, namely YAMC (Apc(+/+)). We found that the induction of PGHS-2 and generation of PGE2 in these cells by IFN-gamma and lipopolysaccharide (LPS) were greatly reduced by two selective NOS II inhibitors, L-NIL and SMT. To ascertain the effect of NO on PGHS-2 overexpression, we tested NO-releasing compounds, NOR-1 and SNAP, and found that they caused PGHS-2 expression and PGE2 production. This effect was abolished by hemoglobin, a NO scavenger. Using electrophoretic mobility shift assays, we found that both NOR-1 and SNAP caused beta-catenin/LEF-1 DNA complex formation. Super-shift by anti-beta-catenin antibody confirmed the presence of beta-catenin in the complex. Cell fractionation studies indicated that NO donors caused an increase in free soluble cytoplasmic beta-catenin. This is further corroborated by the immunocytochemistry data showing the redistribution of beta-catenin from the predominantly membrane localization into the cytoplasm and nucleus after treatment with NO donors. To further explore the possible connection between PGHS-2 expression and beta-catenin/LEF-1 DNA complex formation, we studied IMCE (Apc(Min/+)) cells, a sister cell line of YAMC with similar genetic background but differing in Apc genotype and, consequently, their beta-catenin levels. We found that IMCE cells, in comparison with YAMC cells, had markedly higher beta-catenin/LEF-1 DNA complex formation under both resting conditions as well as after induction with NO. In parallel fashion, IMCE cells expressed significantly higher levels of PGHS-2 mRNA and protein, and generated more PGE2. Overall, this study suggests that NO may be involved in PGHS-2 overexpression in conditionally immortalized mouse colonic epithelial cells. Although the molecular mechanism of the link is still under investigation, this effect of NO appears directly or indirectly to be a result of the increase in free soluble beta-catenin and the formation of nuclear beta-catenin/LEF-1 DNA complex. 相似文献
63.
A Study of Genetic Variation and Relationships within the Bamboo Subtribe Bambusinae using Amplified Fragment Length Polymorphism 总被引:10,自引:1,他引:9
Loh Jin Phang; Kiew Ruth; Set Ohn; Gan Leong Huat; Gan Yik-Yuen 《Annals of botany》2000,85(5):607-612
Taxonomic and systematic studies of the woody bamboos are traditionallybased on floral morphology, which can cause problems in identificationdue to the lack of, or infrequent, flowering. Limited studieshave been conducted using molecular techniques to overcome thisproblem. In this study, we used amplified fragment length polymorphisms(AFLPs) to conduct a study of four genera of bamboos (Bambusa,Dendrocalamus, Gigantochloa andThyrsostachys ) in the subtribeBambusinae. AFLP analysis using eight primer combinations wascarried out on 15 species of bamboo. Results showed that AFLPsdistinguish the different species by their unique banding patterns.Unique AFLPs were detected in 13 of the 15 species examined.The six Bambusa species examined separated into two clusters.The sixGigantochloa species studied formed a discrete clusterdiverging from one of the Bambusa clusters, whileThyrsostachyswas less similar to the Bambusa clusters. The similarity indexbetween B. lako and G. atroviolacea was the highest, suggestingthat B. lako is more appropriately included within the genusGigantochloarather than the genus Bambusa. The two Dendrocalamus speciesexamined were very different with D. brandisii clustering withinone of the Bambusa clusters and D. giganteus appearing as avery distant species. These results support the contention thatcritical study of the genus Dendrocalamus is required. The useof AFLPs for identification of particular bamboo species, aswell as for the study of relationships within the subtribe,will be useful for industrial purposes and for systematic studies.Copyright 2000 Annals of Botany Company Bamboo, Bambusinae, Bambusa, Gigantochloa, Dendrocalamus, Thyrsostachys, AFLP, diversity, AFLP markers 相似文献
64.
Interactions between plasma proteins and pulmonary surfactant: surface balance studies 总被引:1,自引:0,他引:1
K M Keough C S Parsons P T Phang M G Tweeddale 《Canadian journal of physiology and pharmacology》1988,66(9):1166-1173
The influence of human fibrinogen, alpha-globulin, and albumin on the properties of monolayers of pulmonary surfactant under dynamic compression and expansion has been studied at 37 degrees C. Each of the proteins altered some of the properties of the normal compression and expansion isotherms of surfactant such that characteristics deemed desirable for proper lung function were impaired. The order of potency of these effects was fibrinogen greater than globulin greater than albumin. The proteins (a) decreased the maximum surface pressure (equivalent to the minimum surface tension) which the surfactant monolayers attained on compression, (b) decreased the areas occupied per mole of lipid phosphorus when the monolayers were at surface tensions of 20 and 12 mN.m-1, (c) reduced the areas of the hysteresis between compression and expansion isotherms, and (d) decreased the rate of change of surface tension with area at the point of initial expansion of the monolayers. The proteins might compete with surfactant lipid for available space at the interface, especially at low film compression. They might also enhance the desorption of lipid from the monolayer. The findings are consistent with the loss of pulmonary function and presence of edema that occur in adult respiratory distress syndrome being contributed to by plasma proteins interfering with surfactant function. 相似文献
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68.
Takeaki Hanyuda Shogo Arai Masayuki Uchimura Anchana Prathep Stefano G. A. Draisma Siew Moi Phang Isabella A. Abbott Alan J. K. Millar Hiroshi Kawai 《Journal of phycology》2011,47(5):1193-1209
A taxonomic study of the genus Padina from Japan, Southeast Asia, and Hawaii based on morphology and gene sequence data (rbcL and cox3) resulted in the recognition of four new species, that is, Padina macrophylla and Padina ishigakiensis from Ryukyu Islands, Japan; Padina maroensis from Hawaii; and Padina usoehtunii from Myanmar and Thailand. All species are bistratose and morphologically different from one another as well as from any known taxa by a combination of characters relating to degree of calcification; the structure, position, and arrangement of hairlines (HLs) and reproductive sori; and the presence or absence of rhizoid‐like groups of hairs and an indusium. Molecular phylogenetic analyses demonstrated a close relationship between P. ishigakiensis, P. macrophylla, P. maroensis, and Padina australis Hauck. The position of P. usoehtunii, however, was not fully resolved, being either sister to a clade comprising the other three new species and P. australis in the rbcL tree or more closely related to a clade comprising several other recently described species in the cox3 tree. The finding of the four new species demonstrates high species diversity particularly in southern Japan. The following characters were first recognized here to be useful for species delimitation: the presence or absence of small rhizoid‐like groups of hairs on the thallus surface, structure and arrangement of HLs on both surfaces either alternate or irregular, and arrangement of the alternating HLs between both surfaces in equal or unequal distance. The evolutionary trajectory of these and six other morphological characters used in species delineation was traced on the phylogenetic tree. 相似文献
69.
There have been limited reports on molecular sex markers for macroalgae. We report the use of random amplified polymorphic
DNA analysis (RAPD) to identify molecular sex markers for Gracilaria changii (Xia et Abbott) Abbott, Zhang et Xia. Two DNA extraction methods were used: a modified CTAB and phenol-chloroform combination
method and the DNeasy Plant Mini Kit. The CTAB and phenol-chloroform method gave the best yield of DNA in quality and quantity
and is suitable for larger-sized specimens like G. changii. Sixty-nine RAPD primers were screened to search for sex-linked DNA markers for G. changii, and only one sex-linked marker (716 bp) was identified using OPA 18. RAPD was also used to investigate the molecular characteristics
of the three life-stages (male, female, tetrasporophyte) of G. changii. Seven (OPA7, OPA18, S14, S61, S64, S75 and S76) out of the 69 primers showed polymorphism and were selected for interpopulation
analysis for DNA isolated from 23 samples collected from Morib and Sungai Pulai in Malaysia. The combination of data produced
by the seven primers generated a dendrogram that grouped the specimens into different clades according to their sex and life-stage
using the unweighted pair group and arithmetic averages (UPGMA) method. It showed that RAPD was able to differentiate tetrasporophytes,
females, and males.
Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
70.
Sargassum C. Agardh is one of the most common but little understood genera of Phaeophyta in Malaysia. The difficulty in species delineation
is due to morphological plasticity. A combination of morphology and random amplified polymorphic DNA (RAPD) studies of selected
Sargassum species was carried out to have a better understanding of the taxonomy. Primer OPA13 was found to be good for discriminating
between Sargassum species. Sargassum binderi was shown to be different from S. oligocystum (SD>0.5 = 14.11%), indicating the importance of the vesicle and receptacle in species differentiation. S. baccularia was clearly separated out from S. polycystum and S. stolonifolium using primer OPA13. RAPD analysis showed that the presence of the stolon is an important character for separating S. baccularia (no stolon) from S. polycystum (stolon) and S. stolonifolium (stolon).
Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines. 相似文献