Characterization of interstitial stem cells in hydra by cloning

A procedure has been developed for cloning interstitial stem cells from hydra. Clones are prepared by introducing small numbers of viable cells into aggregates of nitrogen mustard-inactivated host tissue. Clones derived from added stem cells are identified after 1–2 weeks of growth by staining with toluidine blue. The incidence of clones increases with increasing input of viable cells according to one-hit Poisson statistics, indicating that clones arise from single cells. After correction for cell losses in the procedure, about 1.2% of the input cells are found to form clones. This compares with estimates from in vivo experiments of about 4% stem cells in whole hydra [David, C. N., and Gierer, A. (1974). Cell cycle kinetics and development of Hydra attenuata. III. Nerve and nematocyte differentiation. J. Cell Sci. 16, 359–375.] Differentiation of nematocytes and nerve cells in clones was analyzed by labeling precursors with [3H]thymidine and scoring labeled nerves and nematocytes 2 days later. Nine clones examined in this way contained both differentiated nerve cells and nematocytes, demonstrating that the interstitial stem cell is multipotent. This result suggests that the observed localization of nerve and nematocyte differentiation in whole hydra probably occurs at the level of stemcell determination. The observation that differentiated cells occur very early in clone development suggests that a stem cell's decision to proliferate or differentiate is regulated by shortrange feedback signals which are already saturated in young clones

A Water Distribution System for Cold Regions: The Single Main Recirculation Method: An Historical Review, Field Evaluation, and Suggested Design Procedures

Students and residents of the Arctic are familiar with the many problems peculiar to the geographical area. This monograph will consider an adequate, safe, and reliable water distribution system. Water supply, together with housing, transportation, and waste disposal, are demanded when a remote area becomes established as a permanent settlement. As long as the population of the North was widely distributed in small mining camps, villages, and individual cabins, water distribution systems were not necessary, as shallow wells and nearby streams adequately served most needs. With the rapidly increasing settlement of the vast lands of the North, the population is being centered in communities rather than distributed over large areas. The world population explosion will undoubtedly contribute to increasing immigration into Arctic and sub-Arctic areas. These changes have already created a need for modern water distribution systems, a need which will become more critical with time.The research upon which this publication is based was performed in accordance with Contract No. ph 86-67-18 with the U.S. Public Health Service, Department of Health, Education, and Welfare. Lastly, the support of the Institute of Water Resources, University of Alaska is acknowledged, through an Office of Water Resources Research grant A-018-Alas

Aboriginal Maple Syrup Values Summary

This report examines the values associated with maple syrup practices in Aboriginal contexts. It is based on fifteen interviews conducted with Aboriginal people who have knowledge of maple syrup practices in Ontario. The interviewees included both First Nations and Metis people

A Program for the Collection, Storage, and Analysis of Baseline Environmental Data for Cook Inlet, Alaska

The scope of this report is to provide a general, yet comprehensive, description of the Cook Inlet System which will serve as a basis for understanding the interrelated natural and man-made factors governing its future; to present a program of field research studies for the estuarine environment that will describe the existing state of the Inlet with respect to the water quality and biota; to provide a framework whereby the program of studies can be evaluated and redirected in light of the preliminary results; and, to provide a method of storing and analyzing the data from the investigations so that it can be made available to interested parties in the most efficient manner possible.This report was prepared by the Institute of Water Resources of the University of Alaska for the Alaska Water Laboratory, Federal Water Pollution Control Administration under Contract No. 14-12-449

BOOTSTRAPPING FORWARD SELECTION WITH BIC

This paper presents a method for bootstrapping the multiple linear regression model Y = β1 + β2x2 +···+ βpxp + e using forward selection with the BIC criterion

Internet2 Musical Performance

The high-speed Abilene network provided by the Internet2 consortium allows for a large variety of uses; it is the intent of this project to determine if the network can allow for musical ensembles to make use of the network to perform with other ensembles at other locations on the network in real-time

An analysis of topics in junior high school American history textbooks

Thesis (M.A.)--Boston University, 1948. This item was digitized by the Internet Archive