Publications by authors named "Charles A Lessman"

Transparent Casper zebrafish allow studies of vertebrate sexual maturation and gonad development in vivo. Casper gonad dynamics can be observed longitudinally over time and non-invasively. Gonad maturation and reproduction are complex processes subject to disruption by endocrine-disrupting chemicals (EDCs), such as diethylstilbestrol (DES).

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Important aspects of vertebrate reproduction, such as gametogenesis, involve changes in organs found deep internally and thus not easily studied directly in most living vertebrates due to obscuring pigment and overlying tissues. Transparent lines of zebrafish, especially the Casper double mutant, allow direct observation and analysis of reproductive events in the gonads in vivo. The natural production of fertilized eggs in zebrafish is a complex process involving oogenesis, spermatogenesis, mating behavior, endocrine and neurological processes with inputs from the environment including light, temperature and nutrition.

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Ever since Edouard Van Beneden and Theodor Boveri first formally described the centrosome in the late 1800s, it has captivated cell biologists. The name clearly indicated its central importance to cell functioning, even to these early investigators. We now know of its role as a major microtubule-organizing center (MTOC) and of its dynamic roles in cell division, vesicle trafficking and for its relative, the basal body, ciliogenesis.

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The zebrafish, Danio rerio, a small, tropical freshwater species native to Pakistan and India, has become a National Institutes of Health-sanctioned model organism and, due to its many advantages as an experimental vertebrate, it has garnered intense interest from the world's scientific community. Some have labeled the zebrafish, the "vertebrate Drosophila," due to its genetic tractability, small size, low cost, and rapid development. The transparency of the embryo, external development, and the many hundreds of mutant and transgenic lines available add to the allure.

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Flatbed transparency scanners are typically relegated to routine office tasks, yet they do offer a variety of potentially useful imaging tools for the zebrafish laboratory. These include motility screens, oocyte maturation and egg activation assays as well as counting and measuring tasks. When coupled with Macroscheduler (http://www.

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The process of oogenesis culminates in steroid-induced oocyte maturation to produce the fertilizable egg. A quintessential biological entity, the egg is central to the production of new individuals. The result of egg fertilization by a sperm cell is the production of the mother of all stem cells (i.

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The tubulin gene family is important for individual zebrafish development from the oocyte through to hatching. This involves often rapid, complex changes in the gametes and embryonic cells that are reflected in underlying gene expression changes. Tubulin dynamics, i.

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Tubulin dynamics, i.e., the interchange of polymeric and soluble forms, is important for microtubule (MTs) cellular functions, and thus plays essential roles in zebrafish oogenesis and embryogenesis.

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We have developed a new technique called Computer-Aided Meiotic Maturation Assay (CAMMA) for imaging large arrays of zebrafish oocytes and automatically collecting image files at regular intervals during meiotic maturation. This novel method uses a transparency scanner interfaced to a computer with macro programming that automatically scans and archives the image files. Images are stacked and analyzed with ImageJ to quantify changes in optical density characteristic of zebrafish oocyte maturation.

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