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151.
Studies in congenitally athymic nude mice grafted with syngeneic thymus enclosed or not in a cell-impermeable Millipore chamber show that the thymus secretes one or several humoral factors controlling the size of the pool of early T-lineage cells produced by the bone marrow. 相似文献
152.
Caffeine is rapidly metabolized in human and mouse cells in culture by demethylation: within 1–3 h of exposure to millimolar concentrations of labeled caffeine, more than 90% of the pool consists of labeled products of metabolism and less than 10% is still caffeine. The metyhl groups seem to be transferred and used in the de novo synthesis of thymine, guanine, and adenine in nucleic acids. Normal fibroblasts, Lesch-Nyhan fibroblasts, xeroderma pigmentosum fibroblasts, HeLa cells, wild type mouse cells, and adenine phosphoribosyl- transferase-deficient mouse cells all seem to metabolize caffeine similarly. 相似文献
153.
Luteinizing hormone levels were measured in blood samples collected at 5 minute (min) intervals for 3 hours (hr) during the a.m. and p.m. of 3 consecutive days from long-term ovariectomized cows. Levels of LH fluctuated in a pulsatile manner in all animals. During the pulses, LH levels increased rapidly (2.5 to 6.0 ng/ml). Following the rapid increase, a more gradual exponential decline was observed. The interval between pulses was consistent both within and between days of blood sample collection within cows. From the results we suggest that each cow may have an inherent consistent rhythmic pattern of LH release in the absence of an ovarian source of hormones. 相似文献
154.
Octopine Ti-plasmid deletion mutants of agrobacterium tumefaciens with emphasis on the right side of the T-region 总被引:31,自引:0,他引:31
Gert Ooms Paul J.J. Hooykaas Ron J.M. Van Veen Patrick Van Beelen Tonny J.G. Regensburg-Tuïnk Rob A. Schilperoort 《Plasmid》1982,7(1):15-29
One hundred and twelve Agrobacterium tumefaciens mutants with a deleted octopine Ti plasmid were isolated. They originated from four insertion mutants, each of which carried the transposon Tn904 at a different position in the Ti plasmid. The deletion mutants were selected on the basis of loss of the capacity encoded by the Ti plasmid to degrade octopine. They were tested for the expression of other Ti-plasmid coded functions: tumor induction, presence of lysopine dehydrogenase activity in the tumor, and exclusion of phage Ap-1. For 21 mutants affected in at least one of these functions, the map position of the deletions was determined. It was found that deletions at two separated loci give rise to an Occ? phenotype. Genes for Ap-1 exclusion were mapped on a small region just outside and to the right of the TL + TR region. Most of the TR region, present as TR-DNA in a limited number of crown gall tissues only, was shown to be unnecessary for tumor formation, since it could be deleted without affecting virulence (tested on various plant species) of the mutants. However, if the TR region together with a small part of the adjacent TL region, which is always present as TL-DNA in normal crown gall tissues, was deleted the mutants became weakly virulent on Kalanchoë and Nicotiana rustica and avirulent on tomato. We hypothesize that in this case a region necessary for T-DNA integration has been deleted. The same region was found to be essential for lysopine dehydrogenase activity in the tumors. 相似文献
155.
A procedure is described whereby phosphorylated seryl residues may be unequivocally identified during the sequential degradation of a polypeptide chain by the Edman technique. The phosphoseryl residue, Ser(P), was first converted by treatment with methylamine in dilute alkali to a β-methylaminoalanyl residue which was split from the polypeptide by the degradative procedure as the derived phenylthiohydantoin. This was identified by high-performance liquid chromatography. The procedure was highly effective when the Ser(P) occupied an isolated position in a polypeptide chain but was less so when grouped consecutively with other Ser(P). 相似文献
156.
Tobias H. Olsen Fergus Boyles Charlotte M. Deane 《Protein science : a publication of the Protein Society》2022,31(1):141
The antibody repertoires of individuals and groups have been used to explore disease states, understand vaccine responses, and drive therapeutic development. The arrival of B‐cell receptor repertoire sequencing has enabled researchers to get a snapshot of these antibody repertoires, and as more data are generated, increasingly in‐depth studies are possible. However, most publicly available data only exist as raw FASTQ files, making the data hard to access, process, and compare. The Observed Antibody Space (OAS) database was created in 2018 to offer clean, annotated, and translated repertoire data. In this paper, we describe an update to OAS that has been driven by the increasing volume of data and the appearance of paired (VH/VL) sequence data. OAS is now accessible via a new web server, with standardized search parameters and a new sequence‐based search option. The new database provides both nucleotides and amino acids for every sequence, with additional sequence annotations to make the data Minimal Information about Adaptive Immune Receptor Repertoire compliant, and comments on potential problems with the sequence. OAS now contains 25 new studies, including severe acute respiratory syndrome coronavirus 2 data and paired sequencing data. The new database is accessible at http://opig.stats.ox.ac.uk/webapps/oas/, and all data are freely available for download. 相似文献
157.
Majority of current treatment strategies against erectile dysfunction (ED) has been consisted of only a supportive care to sustain enough erection during a sexual intercourse. In this study, we investigated whether the cultured conditioned medium of human exfoliated deciduous dental pulp stem cells (SHED‐CM) had an ability to treat ED through fundamentally repairing the pathological damage of vascular endothelial cells of the corpus cavernosum. An open‐label pilot study was performed from April 2016 to October 2020. SHED‐CM was injected directly into the corpus cavernosum of penis of 38 ED patients who visited our clinic and fulfilled the inclusion criteria. Efficacy was assessed using the simplified International Index of Erectile Function (IIEF‐5) questionnaire. The average age and initial IIEF‐5 score of the patients enrolled in this study was 56 (31–79) years old and 13.1 (5–20) points, respectively. Medical history revealed 7 patients with diabetes, 7 patients with hypertension and 1 patient with priapism undergone shunt operation. Of these, 37 patients (97.4%) showed an improvement in IIEF‐5 of an average of 19.3 (7–25) points or 64.4 (10–300) % increase after three injections of SHED‐CM. Eighteen patients (47.4%) achieved more than 21 points (no ED) in IIEF‐5. No adverse events were encountered. This is the first clinical report of ED treatment in the literatures evaluating the efficacy of SHED‐CM. Treatment with SHED‐CM is expected to repair vascular damages of the corpus cavernosum, which are the main cause of ED, and to be widely spread as a fundamental clinical application for ED. 相似文献
158.
Takayuki Hoson Kouichi Soga Ryuji Mori Mizue Saiki Kazuyuki Wakabayashi Seiichiro Kamisaka Shigeki Kamigaichi Sachiko Aizawa Izumi Yoshizaki Chiaki Mukai Toru Shimazu Keiji Fukui Masamichi Yamashita 《Journal of plant research》1999,112(4):477-486
Oryza sativa L.) and Arabidopsis (A. thaliana L.) were cultivated for 68.5 hr in the RICE experiment on board during Space Shuttle STS-95 mission, and changes in their
growth and morphology were analyzed. Microgravity in space stimulated elongation growth of both rice coleoptiles and Arabidopsis hypocotyls by making their cell walls extensible. In space, rice coleoptiles showed an inclination toward the caryopsis in
the basal region and also a spontaneous curvature in the same direction in the elongating region. These inclinations and curvatures
were more prominent in the Koshihikari cultivar compared to a dwarf cultivar, Tan-ginbozu. Rice roots elongated in various
directions including into the air on orbit, but two thirds of the roots formed a constant angle with the axis of the caryopsis.
In space, Arabidopsis hypocotyls also elongated in a variety of directions and about 10% of the hypocotyls grew into the agar medium. No clear
curvatures were observed in the elongating region of Arabidopsis hypocotyls. Such a morphology of both types of seedlings was fundamentally similar to that observed on a 3-D clinostat. Thus,
it was confirmed by the RICE experiment that rice and Arabidopsis seedlings perform an automorphogenesis under not only simulated but also true microgravity conditions.
Received 13 September 1999/ Accepted in revised form 12 October 1999 相似文献
159.
Vitul Agarwal Chase C. James Claire E. Widdicombe Andrew D. Barton 《Ecology and evolution》2021,11(22):15720
It is difficult to make skillful predictions about the future dynamics of marine phytoplankton populations. Here, we use a 22‐year time series of monthly average abundances for 198 phytoplankton taxa from Station L4 in the Western English Channel (1992–2014) to test whether and how aggregating phytoplankton into multi‐species assemblages can improve predictability of their temporal dynamics. Using a non‐parametric framework to assess predictability, we demonstrate that the prediction skill is significantly affected by how species data are grouped into assemblages, the presence of noise, and stochastic behavior within species. Overall, we find that predictability one month into the future increases when species are aggregated together into assemblages with more species, compared with the predictability of individual taxa. However, predictability within dinoflagellates and larger phytoplankton (>12 μm cell radius) is low overall and does not increase by aggregating similar species together. High variability in the data, due to observational error (noise) or stochasticity in population growth rates, reduces the predictability of individual species more than the predictability of assemblages. These findings show that there is greater potential for univariate prediction of species assemblages or whole‐community metrics, such as total chlorophyll or biomass, than for the individual dynamics of phytoplankton species. 相似文献
160.
The space‐time variation of disease risk, considering the closeness and availability of care units, is studied by a hierarchical Bayesian model in a gravitational formulation. The pattern of mortality for Hodgkin's lymphoma over the last twenty‐five years in the Tuscany region and the evaluation of the consequences of distance from the nearest radiation‐therapy center are described. Results show a decrease in mortality for Hodgkin's lymphoma and the attraction exercised by each care units. 相似文献