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91.
92.
Jeffrey A. Pogany Ephraim J. Simon Rebecca B. Katzman Bernadette M. De Guzman Lita Po Yu Amy E. Trotochaud Steven E. Clark 《Journal of plant research》1998,111(2):307-313
New organs are initiated throughout the life span of higher plants. This process occurs at the shoot meristem, which is initiated
during embryogenesis and is later responsible for generating the above-ground portion of the plant. The shoot meristem can
be thought of as having two zones, a central zone containing meristematic cells in an undifferentiated state, and a surrounding
peripheral zone where cells enter a specific developmental pathway toward a differentiated state. Recent advances have revealed
several genes that specifically regulate meristem development inArabidopsis. However, extensive mutagenesis by several labs have identified only a handful, of loci that appear to specifically regulate
shoot meristem development. We have undertaken an enhancer/suppressor mutagenesis of an existing meristem mutant (clv1) and have identified novel regulators of meristem development.
The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International
Prize for Biology “Frontier of Plant Biology” 相似文献
93.
We administered 45 Nd-YAG laser treatments in 29 patients (18 men) aged 39 to 82 years who had lung malignancy; 26 patients had primary non-oat cell lung cancer and three had metastatic airway malignancy. In all, 25 of the patients had been previously treated with combination(s) of surgical procedure, radiation therapy and chemotherapy. Indications for laser treatment included endobronchial airway obstruction with uncontrolled cough, hemoptysis, dyspnea or unresolved atelectasis-pneumonia. Of 15 patients with partially occluded tracheobronchial airway tumors, immediate palliative relief was achieved in 13 patients and lasted one to six months after a single treatment. In this group there was one postoperative death related to respiratory failure and two patients subsequently died of massive pulmonary hemorrhage. However, of 14 patients with totally obstructed airways, immediate palliative relief was achieved in only five patients and this lasted three weeks to three months after a single treatment. In this group there were two postoperative deaths related to progressive respiratory failure; in one case it was associated with endobronchial combustion of the fiberoptic bronchoscope. All three patients in both groups who died of respiratory failure were in acute respiratory distress and terminally ill before the procedure. These findings suggest that Nd-YAG laser therapy may be most beneficial in patients with partially rather than totally occluded airways due to lung malignancy. 相似文献
94.
We have examined the specificity of communication between cells in culture by co-culturing cells derived from mammalian, avian, and arthropod organisms. Both mammalian and avian culture cells have similar gap junctional phenotypes, while the insect (arthropod) cell lines have a significantly different gap junctional structure. Electrophysiological and ultrastructural methods were used to examine ionic coupling and junctional interactions between homologous and heterologous cell types. In homologous cell systems, gap junctions and ionic coupling are present at a high incidence. Also, heterologous vertebrate cells in co-culture can communicate readily. By contrast, practically no coupling (0-8%) is detectable between heterologous insect cell lines (Homopteran or Lepidopteran) and vertebrate cells (mammalian myocardial or 3T3 cells). No gap junctions have been observed between arthropod and vertebrate cell types, even though the heterologous cells may be separated by less than 10 nm. In additional studies, a low incidence of coupling was found between heterologous insect cell lines derived from different arthropod orders. However, extensive coupling was detected between insect cell lines that are derived from the same order (Homoptera). These observations suggest that there is little or no apparent specificity for communication between vertebrate cells in culture that express the same gap junctional phenotype, while there is a definite communication specificity that exists between arthropod cells in culture. 相似文献
95.
Macrophage tropism determinants of human immunodeficiency virus type 1 in vivo. 总被引:16,自引:52,他引:16 下载免费PDF全文
P Westervelt D B Trowbridge L G Epstein B M Blumberg Y Li B H Hahn G M Shaw R W Price L Ratner 《Journal of virology》1992,66(4):2577-2582
Strains of human immunodeficiency virus type 1 differ in their abilities to infect and replicate in primary human macrophages. Chimeric clones were constructed from a provirus unable to infect macrophages (NLHX) and envelope sequences (V3 loop) of viruses derived without cultivation from brain (YU2 and w1-1c1) or spleen (w2-1b4) tissues. The substituted V3 loop sequences in each case were sufficient to confer upon NLHX the ability to infect macrophages. Furthermore, an envelope domain immediately N terminal to the V3 loop also was found to modulate the level of replication in macrophages. These results demonstrate that an envelope determinant derived directly from patients with AIDS confers HIV-1 tropism for macrophages. 相似文献
96.
Sun Hee Ahn Ephraim L. Tsalik Derek D. Cyr Yurong Zhang Jennifer C. van Velkinburgh Raymond J. Langley Seth W. Glickman Charles B. Cairns Aimee K. Zaas Emanuel P. Rivers Ronny M. Otero Tim Veldman Stephen F. Kingsmore Joseph Lucas Christopher W. Woods Geoffrey S. Ginsburg Vance G. Fowler Jr 《PloS one》2013,8(1)
Staphylococcus aureus causes a spectrum of human infection. Diagnostic delays and uncertainty lead to treatment delays and inappropriate antibiotic use. A growing literature suggests the host’s inflammatory response to the pathogen represents a potential tool to improve upon current diagnostics. The hypothesis of this study is that the host responds differently to S. aureus than to E. coli infection in a quantifiable way, providing a new diagnostic avenue. This study uses Bayesian sparse factor modeling and penalized binary regression to define peripheral blood gene-expression classifiers of murine and human S. aureus infection. The murine-derived classifier distinguished S. aureus infection from healthy controls and Escherichia coli-infected mice across a range of conditions (mouse and bacterial strain, time post infection) and was validated in outbred mice (AUC>0.97). A S. aureus classifier derived from a cohort of 94 human subjects distinguished S. aureus blood stream infection (BSI) from healthy subjects (AUC 0.99) and E. coli BSI (AUC 0.84). Murine and human responses to S. aureus infection share common biological pathways, allowing the murine model to classify S. aureus BSI in humans (AUC 0.84). Both murine and human S. aureus classifiers were validated in an independent human cohort (AUC 0.95 and 0.92, respectively). The approach described here lends insight into the conserved and disparate pathways utilized by mice and humans in response to these infections. Furthermore, this study advances our understanding of S. aureus infection; the host response to it; and identifies new diagnostic and therapeutic avenues. 相似文献
97.
Comparing gene discovery from Affymetrix GeneChip microarrays and Clontech PCR-select cDNA subtraction: a case study 总被引:1,自引:0,他引:1
98.
Delayed thymocyte maturation in the trisomy 16 mouse fetus 总被引:1,自引:0,他引:1
Mouse fetuses with trisomy 16, an animal model for human trisomy 21 (Down syndrome), have severe defects in several hematopoietic stem cell populations and a marked reduction in thymocyte number. To determine whether there are other defects in the development of the trisomic thymus, the ontogeny of the cell surface antigenic determinants, Thy-1, Ly-1, CD3, CD4, CD8, and TCR v beta, was investigated. The trisomy 16 thymocytes were able to express all of determinants either during fetal life (days 14 to 19 of gestation) or in cultures of intact thymus lobes. However, in all instances (except for Thy-1, which already had a high proportion of expressing thymocytes by day 14), there was a delay in the time at which the determinants were first expressed, as manifested by reduced numbers of positively staining cells. Furthermore, there was also a delay in the rate at which the positively staining cells attained maximal Ag densities. Overall, there was an approximate 2 day lag in development of the fetal trisomic thymocytes. This lag permitted the identification of a large population of CD4-8+ cells prior to the appearance of CD4+8+ thymocytes. These findings are consistent with the identification of CD4-8+ as an intermediate stage between CD4-8- and CD4+8+ in fetal thymocyte ontogeny. 相似文献
99.
Plant Effects on Spatial and Temporal Patterns of Nitrogen Cycling in Shortgrass Steppe 总被引:6,自引:0,他引:6
Because of the water-limited nature and discontinuous plant cover of shortgrass steppe, spatial patterns in ecosystem properties
are influenced more by the presence or absence of plants than by plant type. However, plant type may influence temporal patterns
of nutrient cycling between plant and soil. Plants having the carbon-3 (C3) or carbon-4 (C4) photosynthetic pathway differ in phenology as well as other attributes that affect nitrogen (N) cycling. We estimated net
N mineralization rates and traced nitrogen-15 (15N) additions among plant and soil components during May, July, and September of 1995 in native plots of C3 plants, C4 plants, or mixtures of C3 and C4. Net N mineralization was significantly greater in C3 plots than in C4 plots during both July and September. C3 plots retained significantly more 15N in May than did mixed and C4 plots; these differences in
15N retention were due to greater 15N uptake by C3 plants than by C4 plants during May. There were no significant differences in total 15N retention among plant communities for July and September. Soil 15N was influenced more by presence or absence of plants than by type of plant; greater quantities of
15N remained in soil interspaces between plants than in soil directly under plants for July and September. Our results indicate
that plant functional type (C3 versus C4) can affect both the spatial and the temporal patterns of N cycling in shortgrass steppe. Further research is necessary to
determine how these intraseasonal differences translate to longer-term and coarser-scale effects of plants on N cycling, retention,
and storage.
Received 8 December 1997; accepted 6 May 1998. 相似文献
100.
A N Epstein 《Journal de physiologie》1984,79(6):496-498
Richter's discovery of the salt appetite that follows adrenalectomy (1936) raised the question: how does the brain appreciate the need for sodium so that it can mobilize the search for and ingestion of salty substances? It remains unanswered. Recent work suggests that the answer may come from an understanding of the behavioral effects of the hormones of sodium conservation. Fluharty and I have found (Behavioral Neuroscience, 1983) that treatment of salt replete rats with low doses of both angiotensin (Ang II) and a mineralocorticoid (DOCA) evokes a rapid, reliable, and specific appetite for sodium solutions, and we have proposed that the hormones of renal sodium conservation are also the hormones for the behavioral defense against sodium deficiency. We can now report: That the same combined endocrine treatment will compel rats that do not need salt to search for it in a runway. That is, sodium replete rats that have been primed for 3 days with DOCA (500 micrograms/day), which does not produce an appetite for salt, and are then given a pulse intracerebroventricular (ICV) injection of Ang II (60 ng), which by itself does not produce an appetite for salt, will run in an alleyway in order to ingest small drops of 3% NaCl. The hormones act together to make the rat avid for salt and their action is sufficient to drive it to seek salt at a distance and to ingest it at a concentration that untreated rats avoid.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献