301 research outputs found
Generation of Inducible CRISPRi and CRISPRa Human Stromal/Stem Cell Lines for Controlled Target Gene Transcription during Lineage Differentiation
Background. Human bone marrow stromal/stem cells (hMSCs, also known as the skeletal stem cells or mesenchymal stem cells) are being employed to study lineage fate determination to osteoblasts, adipocytes, and chondrocytes. However, mechanistic studies employing hMSC have been hampered by the difficulty of deriving genetically modified cell lines due to the low and unstable transfection efficiency. Methods. We infected hMSC with a CRISPR/Cas9 lentivirus system, with specific inducible dCas9-coupled transcription activator or repressor: dCas9-KRAB or dCas9-VP64, respectively, and established two hMSC lines (hMSC-CRISPRi and hMSC-CRISPRa) that can inhibit or activate gene expression, respectively. The two cell lines showed similar cell morphology, cell growth kinetics, and similar lineage differentiation potentials as the parental hMSC line. The expression of KRAB-dCas9 or VP64-dCas9 was controlled by the presence or absence of doxycycline (Dox) in the cell culturing medium. To demonstrate the functionality of the dCas9-effector hMSC system, we tested controlled expression of alkaline phosphatase (ALP) gene through transfection with the same single ALP sgRNA. Results. In the presence of Dox, the expression of ALP showed 60-90% inhibition in hMSC-CRISPRi while ALP showed more than 20-fold increased expression in hMSC-CRISPRa. As expected, the ALP was functionally active and the cells showed evidence for inhibition or enhancement of in vitro osteoblast differentiation, respectively. Conclusion. hMSC-CRISPRi and hMSC-CRISPRa are useful resources to study genes and genetic pathways regulating lineage-specific differentiation of hMSC
Actin depolymerization enhances adipogenic differentiation in human stromal stem cells
Human stromal stem cells (hMSCs) differentiate into adipocytes that play a role in skeletal tissue homeostasis and whole body energy metabolism. During adipocyte differentiation, hMSCs exhibit significant changes in cell morphology suggesting changes in cytoskeletal organization. Here, we examined the effect of direct modulation of actin microfilament dynamics on adipocyte differentiation. Stabilizing actin filaments in hMSCs by siRNA-mediated knock down of the two main actin depolymerizing factors (ADFs): Cofilin 1 (CFL1) and Destrin (DSTN) or treating the cells by Phalloidin reduced adipocyte differentiation as evidenced by decreased number of mature adipocytes and decreased adipocyte specific gene expression (ADIPOQ, LPL, PPARG, FABP4). In contrast, disruption of actin cytoskeleton by Cytochalasin D enhanced adipocyte differentiation. Follow up studies revealed that the effects of CFL1 on adipocyte differentiation depended on the activity of LIM domain kinase 1 (LIMK1) which is the major upstream kinase of CFL1. Inhibiting LIMK by its specific chemical inhibitor LIMKi inhibited the phosphorylation of CFL1 and actin polymerization, and enhanced the adipocyte differentiation. Moreover, treating hMSCs by Cytochalasin D inhibited ERK and Smad2 signaling and this was associated with enhanced adipocyte differentiation. On the other hand, Phalloidin enhanced ERK and Smad2 signaling, but inhibited adipocyte differentiation which was rescued by ERK specific chemical inhibitor U0126. Our data provide a link between restructuring of hMSCs cytoskeleton and hMSCs lineage commitment and differentiation. Keywords: Actin cytoskeleton, Actin depolymerizing factors, Adipocyte differentiation, Human stromal stem cell
Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities
High-redshift Gamma-Ray Bursts (GRBs) beyond redshift are potentially
powerful tools to probe the distant early Universe. Their detections in large
numbers and at truly high redshifts call for the next generation of high-energy
wide-field instruments with unprecedented sensitivity at least one order of
magnitude higher than the ones currently in orbit. On the other hand, follow-up
observations of the afterglows of high-redshift GRBs and identification of
their host galaxies, which would be difficult for the currently operating
telescopes, require new, extremely large facilities of at multi-wavelengths.
This chapter describes future experiments that are expected to advance this
exciting field, both being currently built and being proposed. The legacy of
Swift will be continued by SVOM, which is equipped with a set of space-based
multi-wavelength instruments as well as and a ground segment including a wide
angle camera and two follow-up telescopes. The established Lobster-eye X-ray
focusing optics provides a promising technology for the detection of faint GRBs
at very large distances, based on which the {THESEUS}, {Einstein Probe} and
other mission concepts have been proposed. Follow-up observations and
exploration of the reionization era will be enabled by large facilities such as
{SKA} in the radio, the 30m class telescopes in the optical/near-IR, and the
space-borne {WFIRST} and {JWST} in the optical/near-IR/mid-IR. In addition, the
X-ray and -ray polarization experiment POLAR is also introduced.Comment: accepted for publication in Space Science Review; reprinted as a
chapter in a book of the Space Sciences Series of ISSI for the proceedings of
the ISSI-Beijing workshop " Gamma-Ray Bursts: a Tool to Explore the Young
Universe
Einstein Probe - a small mission to monitor and explore the dynamic X-ray Universe
Einstein Probe is a small mission dedicated to time-domain high-energy
astrophysics. Its primary goals are to discover high-energy transients and to
monitor variable objects in the keV X-rays, at higher sensitivity by
one order of magnitude than those of the ones currently in orbit. Its
wide-field imaging capability, featuring a large instantaneous field-of-view
(, sr), is achieved by using established
technology of micro-pore (MPO) lobster-eye optics, thereby offering
unprecedentedly high sensitivity and large Grasp. To complement this powerful
monitoring ability, it also carries a narrow-field, sensitive follow-up X-ray
telescope based on the same MPO technology to perform follow-up observations of
newly-discovered transients. Public transient alerts will be downlinked
rapidly, so as to trigger multi-wavelength follow-up observations from the
world-wide community. Over three of its 97-minute orbits almost the entire
night sky will be sampled, with cadences ranging from 5 to 25 times per day.
The scientific objectives of the mission are: to discover otherwise quiescent
black holes over all astrophysical mass scales by detecting their rare X-ray
transient flares, particularly tidal disruption of stars by massive black holes
at galactic centers; to detect and precisely locate the electromagnetic sources
of gravitational-wave transients; to carry out systematic surveys of X-ray
transients and characterize the variability of X-ray sources. Einstein Probe
has been selected as a candidate mission of priority (no further selection
needed) in the Space Science Programme of the Chinese Academy of Sciences,
aiming for launch around 2020.Comment: accepted to publish in PoS, Proceedings of "Swift: 10 Years of
Discovery" (Proceedings of Science; ed. by P. Caraveo, P. D'Avanzo, N.
Gehrels and G. Tagliaferri). Minor changes in text, references update
Experimental investigation about the influence of airflow on droplet sizes of mechanical nozzles for coal mining face
Visokotlačno raspršivanje je jedna od primarnih metoda za sprječavanje prašine u potpuno mehaniziranom iskopu, a učinci raspršivanja mehaničkih mlaznica značajno utječu na učinak raspršivanja. Do sada su mlaznice uglavnom odabirane subjektivnom proizvoljnošću tehničara, utječući na poboljšanje učinka suzbijanja prašine. Iz tog razloga, prije i poslije simulacije stvarne brzine zraka iskopa ugljena, provedeni su usporedni pokusi učinaka atomizacije na šest vrsta najčešće korištenih mehaničkih mlaznica s vlastitom platformom za prskanje. Na osnovu podataka o ispitivanju dobivene su prosječne veličine kapljica i redoslijed kvalitete raspršivanja različitih mehaničkih mlaznica, a osim toga je induciran utjecaj turbulencije protoka zraka na veličine kapljica. Konačno, prema eksperimentalnim rezultatima, mlaznice koje se koriste u vanjskom raspršivaču su odabrane za #10310 radnih iskopa rudnika ugljena Xinglongzhuang u Kini, koji je postigao velike učinke smanjenja prašine.High-pressure spraying is one of the primary methods for dust prevention in coal mine fully mechanized caving face, and the atomization effects of mechanical nozzles influence dedusting result significantly. While so far, the nozzles are selected by technician’s subjective arbitrariness mainly, affecting improving dedusting effect. For this reason, before and after simulating actual air velocity of coal workface, the comparative experiments on the atomization effects of the six kinds of commonly used mechanical nozzles were conducted with self-designed spraying platform. Based on the test data, the average droplets’ size and the atomization quality order of different mechanical nozzles were obtained, moreover, the airflow’s turbulence influence on droplets’ sizes was induced. Finally, according to the experimental results, nozzles used in external spray of shearer were selected for #10310 working face of Xinglongzhuang coal mine in China, which had achieved great dust reduction effects
Whole Genome Sequencing and Comparative Genomics Analyses of Pandoraea sp. XY-2, a New Species Capable of Biodegrade Tetracycline
Few bacteria are resistant to tetracycline and can even biodegrade tetracycline in the environment. In this study, we isolated a bacterium Pandoraea sp. XY-2, which could biodegrade 74% tetracycline at pH 7.0 and 30°C within 6 days. Thereafter, we determined the whole genome sequence of Pandoraea sp. XY-2 genome is a single circular chromosome of 5.06 Mb in size. Genomic annotation showed that two AA6 family members-encoding genes and nine glutathione S-transferase (GSTs)-encoding genes could be relevant to tetracycline biodegradation. In addition, the average nucleotide identities (ANI) analysis between the genomes of Pandoraea sp. XY-2 and other Pandoraea spp. revealed that Pandoraea sp. XY-2 belongs to a new species. Moreover, comparative genome analysis of 36 Pandoraea strains identified the pan and specific genes, numerous single nucleotide polymorphisms (SNPs), insertions, and deletion variations (InDels) and different syntenial relationships in the genome of Pandoraea sp. XY-2. Finally, the evolution and the origin analysis of genes related to tetracycline resistance revealed that the six tetA(48) genes and two specificgenes tetG and tetR in Pandoraea sp. XY-2 were acquired by horizontal gene transfer (HGT) events from sources related to Paraburkholderia, Burkholderia, Caballeronia, Salmonella, Vibrio, Proteobacteria, Pseudomonas, Acinetobacter, Flavimaricola, and some unidentified sources. As a new species, Pandoraea sp. XY-2 will be an excellent resource for the bioremediation of tetracycline-contaminated environment
Comparative proteomic analysis reveals alterations in development and photosynthesis-related proteins in diploid and triploid rice
Six pairs of primers were designed for gene-specific transcript amplification. (DOC 25Â kb
A Humanized Anti-VEGF Rabbit Monoclonal Antibody Inhibits Angiogenesis and Blocks Tumor Growth in Xenograft Models
Rabbit antibodies have been widely used in research and diagnostics due to their high antigen specificity and affinity. Though these properties are also highly desirable for therapeutic applications, rabbit antibodies have remained untapped for human disease therapy. To evaluate the therapeutic potential of rabbit monoclonal antibodies (RabMAbs), we generated a panel of neutralizing RabMAbs against human vascular endothelial growth factor-A (VEGF). These neutralizing RabMAbs are specific to VEGF and do not cross-react to other members of the VEGF protein family. Guided by sequence and lineage analysis of a panel of neutralizing RabMAbs, we humanized the lead candidate by substituting non-critical residues with human residues within both the frameworks and the CDR regions. We showed that the humanized RabMAb retained its parental biological properties and showed potent inhibition of the growth of H460 lung carcinoma and A673 rhabdomyosarcoma xenografts in mice. These studies provide proof of principle for the feasibility of developing humanized RabMAbs as therapeutics
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