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11.
Volume 61, no. 9, p. 3323: the title of the article should read as shown above. [This corrects the article on p. 3323 in vol. 61.]. 相似文献
12.
Robert T. Fraley Robert B. Horsch Antonius Matzke Mary-Dell Chilton William S. Chilton Patricia R. Sanders 《Plant molecular biology》1984,3(6):371-378
Summary A method (termed co-cultivation) for transforming plant cells in vitro with A. tumefaciens strains, which was originally developed by Marton et al. (1978) Nature 277: 129–131, has been modified by the incorporation of a novel feeder plate culture system and been extended to use with petunia protoplasts. Using efficient cell plating and selection conditions for phytohormone-independent growth, large numbers of independent transformed calli can be obtained efficiently (10-1) and in less than 3 weeks following protoplast isolation. Southern hybridization analysis has confirmed that the majority of the resulting in vitro transformants contain a single copy of full length T-DNA.The high efficiency of this procedure allows simple screening to identify plant cells transformed by Ti plasmids attenuated by deletion of internal T-DNA regions. Results are presented that demonstrate the co-cultivation method can be used in conjunction with short term assays for monitoring plant gene expression. 相似文献
13.
Summary The projections of horseradish peroxidase-filled axons from each quadrant of the retina were studied to determine whether retinal projections of goldfish are topographically organized in diencephalic target nuclei. A distinct topography of the dorsal, nasal, ventral and temporal retina exists in the lateral geniculate nucleus and in the dorsolateral optic nucleus of the thalamus. The projections of retinal quadrants show minimal spatial overlap in each of these nuclei. The suprachiasmatic nucleus of the hypothalamus is extensively innervated by ventral retinal fibers, whereas the nucleus is sparsely innervated by fibers from the other three retinal quadrants. A rudimentary topography also exists in the pretectum where the dorsal pretectal area receives projections primarily from the ventral retina and the ventral pretectal area receives projections mostly from the dorsal retina. These data show that retinal projections to some diencephalic nuclei are topographically organized.This work was supported by Research Grant EY-01426 to S.C.S. 相似文献
14.
Joyce M. Zarling Cara Berman Peter C. Raich 《Cancer immunology, immunotherapy : CII》1980,7(4):243-249
Summary Peripheral blood lymphocytes from 62 previously treated Hodgkin's and non-Hodgkin's lymphoma patients were tested for their ability to generate cytotoxic T lymphocytes in response to stimulation with allogeneic cells in mixed leukocyte culture. In most patients, including some in long-term unmaintained remission, extremely low cytotoxic responses were generated. To test whether these patients have circulating cells that suppress autologous lymphocytes from responding to alloantigens, patients' responding cells were passaged over columns of sepharose beads conjugated with histamine-rabbit serum albumin (Hist-RSA). This procedure has been shown to remove mouse suppressor cells and Concanavalin A(ConA)-induced human suppressor cells. Passage of patients' cells, prior to allogeneic stimulation, over columns of sepharose beads conjugated with Hist-RSA but not over control RSA columns, resulted in the isolation of lymphocytes that generated increased cytotoxic responses to alloantigens in 18 of 22 patients with initially low cytotoxic responses. These results suggest that the impaired ability of treated Hodgkin's and non-Hodgkin's lymphoma patients' lymphocytes to differentiate into cytotoxic T lymphocytes is at least in part due to the presence of circulating suppressor cells that bear histamine receptors.Scholar of the Leukemia Society of America 相似文献
15.
In vivo intermembrane transfer of phospholipids in the photosynthetic bacterium Rhodopseudomonas sphaeroides. 总被引:17,自引:15,他引:2 下载免费PDF全文
The kinetics of accumulation of phospholipids into the intracytoplasmic membrane of Rhodopseudomonas sphaeroides have been examined. We have previously demonstrated that accumulation of phospholipids in the intracytoplasmic membrane is discontinuous with respect to the cell cycle. In this study we demonstrated a sevenfold increase in the rate of phospholipid incorporation into the intracytoplasmic membrane concurrent with the onset of cell division. Pulse-chase labeling studies revealed that the increase in the rate of phospholipid accumulation into the intracytoplasmic membrane results from the transfer of phospholipid from a site other than the intracytoplasmic membrane, and that the transfer of phospholipid, rather than synthesis of phospholipid, is most likely subject to cell cycle-specific regulation. The rates of synthesis of the individual phospholipid species (phosphatidylethanolamine, phosphatidyglycerol, and an unknown phospholipid) remained constant with respect to one another throughout the cell cycle. Similarly, each of these phospholipid species appeared to be transferred simultaneously to the intracytoplasmic membrane. We also present preliminary kinetic evidence which suggested that phosphatidylethanolamine may be converted to phosphatidycholine within the intracytoplasmic membrane. 相似文献
16.
Pedro Len‐Lobos Marcela A. Bustamante‐Snchez Cara R. Nelson Diego Alarcn Rodrigo Hasbún Michael Way Hugh W. Pritchard Juan J. Armesto 《Restoration Ecology》2020,28(2):277-281
We argue that the need for a quality seed supply chain is a major bottleneck for the restoration of Chile's native ecosystems, thus supplementing the list of bottlenecks proposed by Bannister et al. in 2018. Specifically, there is a need for defining seed transfer zones, developing standards and capacities for properly collecting and storing seeds, reducing information gaps on seed physiology and longevity, and implementing an efficient seed supply chain with certification of seed origin and quality. Without such capacities, countries are unlikely to meet their restoration commitments. Although we focus on bottlenecks in Chile, the issues we raise are relevant to other countries and thus the global agenda for ecological restoration. 相似文献
17.
The first step of many metabolomics studies is quenching, a technique vital for rapidly halting metabolism and ensuring that the metabolite profile remains unchanging during sample processing. The most widely used approach is to plunge the sample into prechilled cold methanol; however, this led to significant metabolite loss in Synecheococcus sp. PCC 7002. Here we describe our analysis of the impacts of cold methanol quenching on the model marine cyanobacterium Synechococcus sp. PCC 7002, as well as our brief investigation of alternative quenching methods. We tested several methods including cold methanol, cold saline, and two filtration approaches. Targeted central metabolites were extracted and metabolomic profiles were generated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results indicate that cold methanol quenching induces dramatic metabolite leakage in Synechococcus, resulting in a majority of central metabolites being lost prior to extraction. Alternatively, usage of a chilled saline quenching solution mitigates metabolite leakage and improves sample recovery without sacrificing rapid quenching of cellular metabolism. Finally, we illustrate that metabolite leakage can be assessed, and subsequently accounted for, in order to determine absolute metabolite pool sizes; however, our results show that metabolite leakage is inconsistent across various metabolite pools and therefore must be determined for each individually measured metabolite. 相似文献
18.
Cara A. Faillace Arnaud Sentis José M. Montoya 《Biological reviews of the Cambridge Philosophical Society》2021,96(5):1933-1950
Eco-evolutionary dynamics can mediate species and community responses to habitat warming and fragmentation, two of the largest threats to biodiversity and ecosystems. The eco-evolutionary consequences of warming and fragmentation are typically studied independently, hindering our understanding of their simultaneous impacts. Here, we provide a new perspective rooted in trade-offs among traits for understanding their eco-evolutionary consequences. On the one hand, temperature influences traits related to metabolism, such as resource acquisition and activity levels. Such traits are also likely to have trade-offs with other energetically costly traits, like antipredator defences or dispersal. On the other hand, fragmentation can influence a variety of traits (e.g. dispersal) through its effects on the spatial environment experienced by individuals, as well as properties of populations, such as genetic structure. The combined effects of warming and fragmentation on communities should thus reflect their collective impact on traits of individuals and populations, as well as trade-offs at multiple trophic levels, leading to unexpected dynamics when effects are not additive and when evolutionary responses modulate them. Here, we provide a road map to navigate this complexity. First, we review single-species responses to warming and fragmentation. Second, we focus on consumer–resource interactions, considering how eco-evolutionary dynamics can arise in response to warming, fragmentation, and their interaction. Third, we illustrate our perspective with several example scenarios in which trait trade-offs could result in significant eco-evolutionary dynamics. Specifically, we consider the possible eco-evolutionary consequences of (i) evolution in thermal performance of a species involved in a consumer–resource interaction, (ii) ecological or evolutionary changes to encounter and attack rates of consumers, and (iii) changes to top consumer body size in tri-trophic food chains. In these scenarios, we present a number of novel, sometimes counter-intuitive, potential outcomes. Some of these expectations contrast with those solely based on ecological dynamics, for example, evolutionary responses in unexpected directions for resource species or unanticipated population declines in top consumers. Finally, we identify several unanswered questions about the conditions most likely to yield strong eco-evolutionary dynamics, how better to incorporate the role of trade-offs among traits, and the role of eco-evolutionary dynamics in governing responses to warming in fragmented communities. 相似文献
19.
20.
Cara N. Halldin Eva Suarthana Kathleen B. Fedan Yi-Chun Lo George Turabelidze Kathleen Kreiss 《PloS one》2013,8(2)