A variance formula for gene mutation studies using agar plates.

H S Javitz

doi:10.1002/em.2860120105

Home/Archive/PubMed

PubMed · 3383838

A variance formula for gene mutation studies using agar plates.

H S Javitz

View original source ↗Export metadata ↓

Abstract

Previous attempts to derive a formula for the variance of the estimated mutant fraction have assumed (without providing justification) that variance components due to treatment, growth and dilution, and plating, are additive. We have derived a variance formula that does not depend on this assumption. Our formula also includes variability attributable to imprecise counting of cells to be plated in the non-selective conditions.

Explore related subjects

Agar Analysis of Variance Cells, Cultured Culture Techniques Mutation Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

H S Javitz. 1988. A variance formula for gene mutation studies using agar plates.. https://doi.org/10.1002/em.2860120105

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Fabrication of agar-gelatin hybrid scaffolds using a novel entrapment method for in vitro tissue engineering applications.

Scaffolds of agar and gelatin were developed using a novel entrapment method where agar and gelatin molecules mutually entrapped one another forming stable cell adhesive matrices. Glutaraldehyde was used as a crosslinking agent for gelatin. Three types of hybrid matrices were prepared using agar and gelatin in different proportions in the weight ratio of 1:1, 2:1, and 3:1. Surface characterization of dry scaffolds was carried out by scanning electron microscope. Swelling studies were carried out in phosphate buffer saline (PBS) at physiological pH 7.4. The integral stability of the scaffolds was evaluated by estimating the released disintegrated gelatin from them in PBS at pH 7.4. The attachment kinetics of the cells was evaluated by culturing mouse fibroblast cell line NIH 3T3 on films. The cytocompatibility of these matrices was determined by studying growth kinetics of NIH 3T3 cells on them and morphology of cells was observed through optical photographs taken at various days of culture. It was found that the matrices containing agar and gelatin in 2:1 weight ratio exhibited best growth kinetics. The results obtained from these studies have suggested that the above-described method is a cheap and easy way to fabricate agar-gelatin hybrid scaffolds to grow cells which can be used in various in vitro tissue engineering applications like screening of drugs.

Agar↗

PubMed2007

Interrelationships between colonies, biofilms, and planktonic cells of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a gram-negative bacterium and an opportunistic human pathogen that causes chronic infections in immunocompromised individuals. These infections are hard to treat, partly due to the high intrinsic resistance of the bacterium to clinically used antibiotics and partly due to the formation of antibiotic-tolerant biofilms. The three most common ways of growing bacteria in vitro are as planktonic cultures, colonies on agar plates, and biofilms in continuous-flow systems. Biofilms are known to express genes different from those of planktonic cells, and biofilm cells are generally believed to closely resemble planktonic cells in stationary phase. However, few, if any, studies have examined global gene expression in colonies. We used a proteomic approach to investigate the interrelationships between planktonic cells, colonies, and biofilms under comparable conditions. Our results show that protein profiles in colonies resemble those of planktonic cells. Furthermore, contrary to what has been reported previously, the protein profiles of biofilms were found to more closely resemble those of exponentially growing planktonic cells than those of planktonic cells in the stationary phase. These findings raise some intriguing questions about the true nature of biofilms.

Agar↗

PubMed2007

Methods for additive hydration allowing observation of fully hydrated state of wet samples in environmental SEM.

Methods for additive hydration are presented that enable longtime observation of very wet biological specimens in an environmental scanning electron microscope. The changes of structure due to dehydration for specimens placed on a Peltier-cooled holder, put on a special agar base or embedded in it or blown over by water vapor are compared. The degree of dehydration damage of the observed specimen structures is evaluated and compared with the structure of a nondestructively dried specimen, prepared by the critical point drying method.

Agar↗