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161.
John Godwin 《Seminars in cell & developmental biology》2009,20(3):264-270
Many fishes living in reef environments display remarkable flexibility in sexuality with social interactions determining their sex either during juvenile development or in adulthood. The evolutionary advantages of such flexibility are relatively well established. By contrast, the mechanisms by which social cues guide development of the sexual phenotype are less well understood. This paper reviews our understanding of these processes for some well-studied reef fish groups at the gonadal and neuroendocrine levels as well as proposing promising directions for future study. 相似文献
162.
Background
Metabolic states of neoplastic cells are increasingly being relied upon for diagnostic and prognostic assessment of neoplastic conditions. The nucleic acid distribution pattern of cells in general, in terms of degree of condensation of the nuclear chromatin and overall spread of the nucleic acid within the nuclear and cytoplasmic compartments, can reflect the metabolic state of the cell. This simple but logical concept appears not be put into consideration to date as numerous attempts are being made towards formulating reliable biomarkers for rapid diagnosis, prognosis and subsequent therapeutic interventions for neoplastic conditions. We comparatively evaluated nucleic acid distribution patterns of normal lymphocytes and neoplastic cells of lymphocytic lineage, employing light and fluorescence microscopy procedures, as well as digital imaging analytical methods. 相似文献163.
Cheong C Matos I Choi JH Dandamudi DB Shrestha E Longhi MP Jeffrey KL Anthony RM Kluger C Nchinda G Koh H Rodriguez A Idoyaga J Pack M Velinzon K Park CG Steinman RM 《Cell》2010,143(3):416-429
Dendritic cells (DCs), critical antigen-presenting cells for immune control, normally derive from bone marrow precursors distinct from monocytes. It is not yet established if the large reservoir of monocytes can develop into cells with critical features of DCs in vivo. We now show that fully differentiated monocyte-derived DCs (Mo-DCs) develop in mice and DC-SIGN/CD209a marks the cells. Mo-DCs are recruited from blood monocytes into lymph nodes by lipopolysaccharide and live or dead gram-negative bacteria. Mobilization requires TLR4 and its CD14 coreceptor and Trif. When tested for antigen-presenting function, Mo-DCs are as active as classical DCs, including cross-presentation of proteins and live gram-negative bacteria on MHC I in vivo. Fully differentiated Mo-DCs acquire DC morphology and localize to T cell areas via L-selectin and CCR7. Thus the blood monocyte reservoir becomes the dominant presenting cell in response to select microbes, yielding DC-SIGN(+) cells with critical functions of DCs. 相似文献
164.
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166.
We sampled periphyton communities in a highly productive stream to characterize how longitudinal changes in watershed geology
and land use affect periphyton nutrient status and elemental composition. Nutrient status was evaluated from measures of periphyton
nutrient composition (carbon, nitrogen, and phosphorus), stable isotope signatures (δ15N and δ13C), and the response of periphyton to experimental enrichment with nitrogen. Biomass and nutrient content increased dramatically
from the headwaters to downstream, while tissue nutrient ratios (C:P and C:N) were more consistent and did not indicate strong
N- or P-limitation. Nitrogen enrichment experiments did not exhibit a consistent response upstream or downstream, and periphyton
C:N:P stoichiometry showed no significant response to N-enrichment. Absolute densities of periphyton N were 5- to 90-fold
greater than the overlying N concentrations in stream water (159- to 353-fold greater for P), and the δ15N signal indicates downstream enrichment from likely watershed sources (urban and agriculture land-use). These results suggest
that periphyton in Spring Creek are not N-limited and store large quantities of both N and P, which in turn can be transported
downstream during high flow events.
Handling editor: David Hamilton 相似文献
167.
Frank Riske Nicole Berard Karen Albee Peng Pan Mike Henderson Kris Adams Simon Godwin Sherri Spear 《Biotechnology and bioengineering》2013,110(3):848-856
The manufacturing of virus occurs at a modest scale in comparison to many therapeutic proteins mainly because a gene therapy dose is typically only µg of vector. Although modest in scale the generation of high purity virus is challenging due to low viral expression levels and the difficulties in adequately characterizing such a large and complex molecule. A 100 L bioreactor might produce only 100 mg of virus that must be separated from host and process impurities that are typically greater by several orders of magnitude. Furthermore, in the later purification stages the main milieu component is often virus at low concentration (µg/mL) which may non‐specifically adsorb to purification surfaces resulting in a lowered virus recovery. This study describes our approach to develop a scalable, manufacturable robust process for an Adenovirus (Ad) gene therapy vector. A number of analytical tools were developed to guide the purification design. During process development, two human proteins, SET and nucleolin, were identified in viral preparations. To our knowledge, this is the first time that SET and nucleolin have been described in Ad. In this report we detail a process for their removal and the robust removal of all process, product and host cell impurities. Biotechnol. Bioeng. 2013; 110: 848–856. © 2012 Wiley Periodicals, Inc. 相似文献
168.
Venus Elec Celsa A. Quimio Rhulyx Mendoza Andres Godwin C. Sajise Sarah E. J. Beebout Glenn B. Gregorio Rakesh Kumar Singh 《Plant and Soil》2013,372(1-2):253-264
Background and aims
Iron toxicity decreases rice (Oryza sativa) grain yield especially in acid soils after flooding. Our aim was to establish a high-throughput screening technique using nutrient solution culture for identifying Fe-toxicity-tolerant genotypes.Methods
Varying levels of Fe, pH, and chelators in Yoshida nutrient solution culture were tested to maintain sufficient Fe2+ concentration over time to optimize the severity of Fe toxicity stress for distinguishing between a tolerant (Azucena) and sensitive (IR64) genotype. The optimized solution was tested on 20 diverse genotypes in the greenhouse, with measurement of leaf bronzing scores and plant growth characteristics at the seedling stage. The same 20 genotypes were grown to maturity in a field with natural Fe toxicity stress, with measurement of seedling-stage leaf bronzing scores and grain yield to determine their inter-relationship.Results
Optimized nutrient solution conditions were 300 mg L?1 Fe supplied as Fe2+ at pH 4.0 with a 1:2 molar ratio of Fe:EDTA, which maintained sufficient Fe2+ stress over 5 days. The highest correlation of nutrient solution phenotypic data with field grain yield was found with leaf bronzing scores at 4 weeks, with a Pearson r of 0.628 for simple association and a Spearman corrected r of 0.610 for rank association (P?<?0.01) using 20 diverse rice genotypes with proven Fe toxicity tolerance reaction. The Leaf bronzing scores at 4 weeks in nutrient culture solution were also found highly correlated with LBS under natural field stress after 8 weeks that had highest correlation with grain yield under stress.Conclusion
This culture solution-based standardized screening technique can be used in plant breeding programs as a high-throughput technique to identify genotypes tolerant to Fe toxicity. 相似文献169.
Benjamin J Alper Godwin Job Rajesh K Yadav Sreenath Shanker Brandon R Lowe Janet F Partridge 《The EMBO journal》2013,32(17):2321-2335
Heterochromatin assembly in fission yeast depends on the Clr4 histone methyltransferase, which targets H3K9. We show that the histone deacetylase Sir2 is required for Clr4 activity at telomeres, but acts redundantly with Clr3 histone deacetylase to maintain centromeric heterochromatin. However, Sir2 is critical for Clr4 function during de novo centromeric heterochromatin assembly. We identified new targets of Sir2 and tested if their deacetylation is necessary for Clr4‐mediated heterochromatin establishment. Sir2 preferentially deacetylates H4K16Ac and H3K4Ac, but mutation of these residues to mimic acetylation did not prevent Clr4‐mediated heterochromatin establishment. Sir2 also deacetylates H3K9Ac and H3K14Ac. Strains bearing H3K9 or H3K14 mutations exhibit heterochromatin defects. H3K9 mutation blocks Clr4 function, but why H3K14 mutation impacts heterochromatin was not known. Here, we demonstrate that recruitment of Clr4 to centromeres is blocked by mutation of H3K14. We suggest that Sir2 deacetylates H3K14 to target Clr4 to centromeres. Further, we demonstrate that Sir2 is critical for de novo accumulation of H3K9me2 in RNAi‐deficient cells. These analyses place Sir2 and H3K14 deacetylation upstream of Clr4 recruitment during heterochromatin assembly. 相似文献
170.