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31.
Kelly OG Chan MY Martinson LA Kadoya K Ostertag TM Ross KG Richardson M Carpenter MK D'Amour KA Kroon E Moorman M Baetge EE Bang AG 《Nature biotechnology》2011,29(8):750-756
Using a flow cytometry-based screen of commercial antibodies, we have identified cell-surface markers for the separation of pancreatic cell types derived from human embryonic stem (hES) cells. We show enrichment of pancreatic endoderm cells using CD142 and of endocrine cells using CD200 and CD318. After transplantation into mice, enriched pancreatic endoderm cells give rise to all the pancreatic lineages, including functional insulin-producing cells, demonstrating that they are pancreatic progenitors. In contrast, implanted, enriched polyhormonal endocrine cells principally give rise to glucagon cells. These antibodies will aid investigations that use pancreatic cells generated from pluripotent stem cells to study diabetes and pancreas biology. 相似文献
32.
Ankareddi I Bailey MM Brazel CS Rasco JF Hood RD 《Birth defects research. Part B, Developmental and reproductive toxicology》2008,83(2):112-116
BACKGROUND: Although polymers and hydrogels are used successfully in biomedical applications, including implants and drug delivery devices, smaller molecular weight oligomers, such as those investigated here, have not been extensively studied in vivo. Poly(N‐isopropylacrylamide‐co‐acrylamide), or P(NIPAAm‐co‐AAm), has a unique thermoresponsive behavior and is under investigation as a novel drug delivery system for metastatic cancer treatment. To date, no studies have been published regarding the safety of P(NIPAAm‐co‐AAm) to the conceptus. METHODS: From gestation days (GD) 6–16, pregnant CD‐1 mice were dosed via i.p. injection with aqueous solutions containing 500, 750, or 1,000 mg/kg/d P(NIPAAm‐co‐AAm). Dams were sacrificed on GD 17 and their litters were examined for abnormalities. RESULTS: P(NIPAAm‐co‐AAm) caused no statistically significant difference in maternal weight gain or percent resorbed or dead fetuses compared to control values, but fetal weight was significantly decreased in the two highest dosage groups. CONCLUSIONS: At the highest dosages employed, maternal exposure to P(NIPAAm‐co‐AAm) was associated with decreased fetal weight. However, as the estimated human exposure levels for persons using this system would be some 1,500‐fold lower than the lowest dosage administered in this study, the authors feel that this oligomer was not shown to pose a biologically significant risk at relevant human dosages. Birth Defects Res (Part B), 2008. © 2008 Wiley‐Liss, Inc. 相似文献
33.
A biowaste kill system was implemented to treat biological waste generated from a clinical manufacturing and R&D antibody facility. To confirm that design parameters of this continuous decontamination system are sufficient to inactivate mammalian cell culture waste, bench-scale experiments were conducted. The biowaste kill system heat inactivates mammalian cell cultures before they are piped to a neutralization tank and subsequently released to the sewage system. Heat inactivation of cells is accomplished by exposing cells to 80 degrees C for 1 min. Small-scale heat inactivation studies were performed on CHO, 293-HEK, and hybridoma cells. Cells at 1 x 10(6) cells/mL or 1 x 10(7) cells/mL were exposed to 37, 60, 70, or 80 degrees C for 0, 30, 60, and 120 s. Viability based on trypan blue exclusion method and ability to proliferate was assessed after exposure to heat. Data suggest that exposure of cells to 80 degrees C for 60 s is sufficient to inactivate these cultures before they are released to the sewage system. 相似文献
34.
Reddy R Buckley S Doerken M Barsky L Weinberg K Anderson KD Warburton D Driscoll B 《American journal of physiology. Lung cellular and molecular physiology》2004,286(4):L658-L667
Alveolar epithelial type 2 cells (AEC2) isolated from hyperoxia-treated animals exhibit increases in both proliferation and DNA damage in response to culture. AEC2 express the zonula adherens proteins E-cadherin, -, - and -catenin, desmoglein, and pp120, as demonstrated by Western blotting. Immunohistochemical analysis of cultured AEC2 showed expression of E-cadherin on cytoplasmic membranes varying from strongly to weakly staining. When cultured AEC2 placed in suspension were labeled with fluorescent-tagged antibodies to E-cadherin, cells could be sorted into at least two subpopulations, either dim or brightly staining for this marker. With the use of antibody to E-cadherin bound to magnetic beads, cells were physically separated into E-cadherin-positive and -negative subpopulations, which were then analyzed for differences in proliferation and DNA damage. The E-cadherin-positive subpopulation contained the majority of damaged cells, was quiescent, and expressed low levels of telomerase activity, whereas the E-cadherin-negative subpopulation was undamaged, proliferative, and expressed high levels of telomerase activity. 相似文献
35.
Kakajan Komurov Jen‐Te Tseng Melissa Muller Elena G Seviour Tyler J Moss Lifeng Yang Deepak Nagrath Prahlad T Ram 《Molecular systems biology》2012,8(1)
Dynamic interactions between intracellular networks regulate cellular homeostasis and responses to perturbations. Targeted therapy is aimed at perturbing oncogene addiction pathways in cancer, however, development of acquired resistance to these drugs is a significant clinical problem. A network‐based computational analysis of global gene expression data from matched sensitive and acquired drug‐resistant cells to lapatinib, an EGFR/ErbB2 inhibitor, revealed an increased expression of the glucose deprivation response network, including glucagon signaling, glucose uptake, gluconeogenesis and unfolded protein response in the resistant cells. Importantly, the glucose deprivation response markers correlated significantly with high clinical relapse rates in ErbB2‐positive breast cancer patients. Further, forcing drug‐sensitive cells into glucose deprivation rendered them more resistant to lapatinib. Using a chemical genomics bioinformatics mining of the CMAP database, we identified drugs that specifically target the glucose deprivation response networks to overcome the resistant phenotype and reduced survival of resistant cells. This study implicates the chronic activation of cellular compensatory networks in response to targeted therapy and suggests novel combinations targeting signaling and metabolic networks in tumors with acquired resistance. 相似文献
36.
Melissa K. Wilson Alison B. Lane Bibiana F. Law William G. Miller Lynn A. Joens Michael E. Konkel Bryan A. White 《Microbial ecology》2009,58(4):843-855
Campylobacter jejuni is one of the leading bacterial causes of food-borne illness in the USA. Molecular typing methods are often used in food
safety for identifying sources of infection and pathways of transmission. Moreover, the identification of genetically related
isolates (i.e., clades) may facilitate the development of intervention strategies for control and prevention of food-borne
diseases. We analyzed the pan genome (i.e., core and variable genes) of 63 C. jejuni isolates recovered from chickens raised in conventional, organic, and free-range poultry flocks to gain insight into the
genetic diversity of C. jejuni isolates recovered from different environments. We assessed the discriminatory power of three genotyping methods [i.e., pulsed-field
gel electrophoresis (PFGE), multilocus sequence typing (MLST), and repetitive extragenic palindromic polymerase chain reaction
(rep-PCR)]. The rep-PCR fingerprint was generated by determining the presence of repetitive sequences that are interspersed throughout
the genome via repetitive extragenic palindromic PCR, enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR),
and BOX element PCR (BOX-PCR) and combining the data to form a composite fingerprint. The genetic fingerprints were subjected
to computer-assisted pattern analysis. Comparison of the three genotypic methods revealed that repREB-PCR showed greater discriminatory
power than PFGE and MLST. ERIC-PCR and BOX-PCR yielded the highest number of PCR products and greatest reproducibility. Regardless
of the genotyping method, C. jejuni isolates recovered from chickens reared in conventional, organic, and free-range environments all exhibit a high level of
genotypic diversity. 相似文献
37.
Inagaki YS Etherington G Geisler K Field B Dokarry M Ikeda K Mutsukado Y Dicks J Osbourn A 《The New phytologist》2011,191(2):432-448
The first committed step in sterol biosynthesis in plants involves the cyclization of 2,3-oxidosqualene by the oxidosqualene cyclase (OSC) enzyme cycloartenol synthase. 2,3-Oxidosqualene is also a precursor for triterpene synthesis. Antimicrobial triterpenes are common in dicots, but seldom found in monocots, with the notable exception of oat. Here, through genome mining and metabolic engineering, we investigate the potential for triterpene synthesis in rice. The first two steps in the oat triterpene pathway are catalysed by a divergent OSC (AsbAS1) and a cytochrome P450 (CYP51). The genes for these enzymes form part of a metabolic gene cluster. To investigate the origins of triterpene synthesis in monocots, we analysed systematically the OSC and CYP51 gene families in rice. We also engineered rice for elevated triterpene content. We discovered a total of 12 OSC and 12 CYP51 genes in rice and uncovered key events in the evolution of triterpene synthesis. We further showed that the expression of AsbAS1 in rice leads to the accumulation of the simple triterpene, β-amyrin. These findings provide new insights into the evolution of triterpene synthesis in monocots and open up opportunities for metabolic engineering for disease resistance in rice and other cereals. 相似文献
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Design and visualization of second‐generation cyanoisoindole‐based fluorescent strigolactone analogs
Melissa Van Overtveldt Lukas Braem Sylwia Struk Anna M. Kaczmarek Franois‐Didier Boyer Rik Van Deun Kris Gevaert Sofie Goormachtig Thomas S. A. Heugebaert Christian V. Stevens 《The Plant journal : for cell and molecular biology》2019,98(1):165-180
Strigolactones (SLs) are a family of terpenoid allelochemicals that were recognized as plant hormones only a decade ago. They influence a myriad of both above‐ and below‐ground developmental processes, and are an important survival strategy for plants in nutrient‐deprived soils. A rapidly emerging approach to gain knowledge on hormone signaling is the use of traceable analogs. A unique class of labeled SL analogs was constructed, in which the original tricyclic lactone moiety of natural SLs is replaced by a fluorescent cyanoisoindole ring system. Biological evaluation as parasitic seed germination stimulant and hypocotyl elongation repressor proved the potency of the cyanoisoindole strigolactone analogs (CISAs) to be comparable to the commonly accepted standard GR24. Additionally, via a SMXL6 protein degradation assay, we provided molecular evidence that the compounds elicit SL‐like responses through the natural signaling cascade. All CISAs were shown to exhibit fluorescent properties, and the high quantum yield and Stokes shift of the pyrroloindole derivative CISA‐7 also enabled in vivo visualization in plants. In contrast to the previously reported fluorescent analogs, CISA‐7 displays a large similarity in shape and structure with natural SLs, which renders the analog a promising tracer to investigate the spatiotemporal distribution of SLs in plants and fungi. 相似文献