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81.
A novel cell division factor from tobacco 2B-13 cells that induced cell division in auxin-starved tobacco BY-2 cells 总被引:1,自引:0,他引:1
Shimizu T Eguchi K Nishida I Laukens K Witters E Van Onckelen H Nagata T 《Die Naturwissenschaften》2006,93(6):278-285
Effects of auxin as plant hormones are widespread; in fact in almost all aspects of plant growth and development auxin plays
a pivotal role. Although auxin is required for propagating cell division in plant cells, its effect upon cell division is
least understood. If auxin is depleted from the culture medium, cultured cells cease to divide. It has been demonstrated in
this context that the addition of auxin to auxin-starved nondividing tobacco BY-2 cells induced semisynchronous cell division.
On the other hand, there are some cell lines, named habituated cells, that can grow without auxin. The cause and reason for
the habituated cells have not been clarified. A habituated cell line named 2B-13 is derived from the tobacco BY-2 cell line,
which has been most intensively studied among plant cell lines. When we tried to find the difference between two cell lines
of BY-2 and 2B-13 cells, we found that the addition of culture filtrated from the auxin-habituated 2B-13 cells induced semisynchronous
cell division in auxin-starved BY-2 cells. The cell division factor (CDF) that is responsible for inducing cell division in
auxin-starved BY-2 cells was purified to near-homogeneity by sequential passage through a hydroxyapatite column, a ConA Sepharose
column and a Sephadex gel filtration column. The resulting purified fraction appeared as a single band of high molecular weight
on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels by silver staining and was able to induce cell division
in auxin-starved BY-2 cells. Identification of the protein by MALD-TOF-MS/MS revealed that it is structurally related to P-glycoprotein
from Gossypioides kirkii, which belongs to ATP-binding cassette (ABC)-transporters. The significance of CDF as a possible ABC-transporter is discussed
in relationship to auxin–autotrophic growth and auxin-signaling pathway. 相似文献
82.
Erwin de Gelder Jan-Pieter Paardekooper Olaf Op den Camp Bart De Schutter 《Traffic injury prevention》2019,20(4):S162-S170
AbstractObjective: The amount of collected field data from naturalistic driving studies is quickly increasing. The data are used for, among others, developing automated driving technologies (such as crash avoidance systems), studying driver interaction with such technologies, and gaining insights into the variety of scenarios in real-world traffic. Because data collection is time consuming and requires high investments and resources, questions like “Do we have enough data?,” “How much more information can we gain when obtaining more data?,” and “How far are we from obtaining completeness?” are highly relevant. In fact, deducing safety claims based on collected data—for example, through testing scenarios based on collected data—requires knowledge about the degree of completeness of the data used. We propose a method for quantifying the completeness of the so-called activities in a data set. This enables us to partly answer the aforementioned questions.Method: In this article, the (traffic) data are interpreted as a sequence of different so-called scenarios that can be grouped into a finite set of scenario classes. The building blocks of scenarios are the activities. For every activity, there exists a parameterization that encodes all information in the data of each recorded activity. For each type of activity, we estimate a probability density function (pdf) of the associated parameters. Our proposed method quantifies the degree of completeness of a data set using the estimated pdfs.Results: To illustrate the proposed method, 2 different case studies are presented. First, a case study with an artificial data set, of which the underlying pdfs are known, is carried out to illustrate that the proposed method correctly quantifies the completeness of the activities. Next, a case study with real-world data is performed to quantify the degree of completeness of the acquired data for which the true pdfs are unknown.Conclusion: The presented case studies illustrate that the proposed method is able to quantify the degree of completeness of a small set of field data and can be used to deduce whether sufficient data have been collected for the purpose of the field study. Future work will focus on applying the proposed method to larger data sets. The proposed method will be used to evaluate the level of completeness of the data collection on Singaporean roads, aimed at defining relevant test cases for the autonomous vehicle road approval procedure that is being developed in Singapore. 相似文献
83.
R. Michael Erwin G. Michael Haramis David G. Krementz Steven L. Funderburk 《Environmental management》1993,17(5):613-619
Many living resources in the Chesapeake Bay estuary have deteriorated over the past 50 years. As a result, many governmental
committees, task forces, and management plans have been established. Most of the recommendations for implementing a bay cleanup
focus on reducing sediments and nutrient flow into the watershed. We emphasize that habitat requirements other than water
quality are necessary for the recovery of much of the bay's avian wildlife, and we use a waterbird example as illustration.
Some of these needs are: (1) protection of fast-eroding islands, or creation of new ones by dredge deposition to improve nesting
habitat for American black ducks(Anas rubripes), great blue herons(Ardea herodias), and other associated wading birds; (2) conservation of remaining brackish marshes, especially near riparian areas, for feeding
black ducks, wading birds, and wood ducks(Aix sponsa); (3) establishment of sanctuaries in open-water, littoral zones to protect feeding and/or roosting areas for diving ducks
such as canvasbacks(Aythya valisineria) and redheads(Aythya americana), and for bald eagles(Haliaeetus leucocephalus); and (4) limitation of disturbance by boaters around nesting islands and open-water feeding areas. Land (or water) protection
measures for waterbirds need to include units at several different spatial scales, ranging from “points” (e.g., a colony site)
to large-area resources (e.g., a marsh or tributary for feeding). Planning to conserve large areas of both land and water
can be achieved following a biosphere reserve model. Existing interagency committees in the Chesapeake Bay Program could be
more effective in developing such a model for wildlife and fisheries resources. 相似文献
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