ISOLATION AND CHARACTERIZATION OF A CELL WALL‐DEFECTIVE MUTANT OF CHLAMYDOMONAS MONOICA (CHLOROPHYTA)¹

Abstract

Cell wall-defective strains of Chlamydomonas have played an important role in the development of transformation protocols for introducing exogenous DNA (foreign genes or cloned Chlamydomonas genes) into C. reinhardtii. To promote the development of similar protocols for transformation of the distantly related homothallic species, C. monoica, we used UV mutagenesis to obtain a mutant strain with a defective cell wall. The mutant, cw-1, was first identified on the basis of irregular colony shape and was subsequently shown to have reduced plating efficiency and increased sensitivity to lysis by a nonionic detergent as compared with wild-type cells. Tetrad analysis of crosses involving the cw-1 mutant confirmed 2:2 segregation of the cw:cw + phenotypes, indicating that the wall defect resulted from mutation of a single nuclear gene. The phenotype showed incomplete penetrance and variable expressivity. Although some cells had apparently normal cell walls as viewed by TEM, many cells of the cw-1 strain had broken cell walls and others were protoplasts completely devoid of a cell wall. Several cw-1 isolates obtained from crosses involving the original mutant strain showed a marked enhancement of the mutant phenotype and may prove especially useful for future work involving somatic cell fusions or development of transformation protocols.

Chlamydomonas reinhardtiiHas Multiple Prolyl 4-Hydroxylases, One of Which Is Essential for Proper Cell Wall Assembly

“…Defects in the cell wall do not necessarily lead to growth problems, for example, some strains of the cw-1 mutant of Chlamydomonas monoica have a faster and some slower doubling times relative to the wild-type cells (Fuentes and VanWinkle-Swift, 2003).…”

Isolation and proteomic alalysis of cell wall-deficientHaematococcus pluvialis mutants

“…Because transformation efficiency is higher with wall-less cells than with walled cells, cell wall mutants, such as those generated from Chlamydomonas, have also found widespread use as recipients for exogenous gene transformation and expression. This further illustrates the usefulness of cell wall mutants for studying wall biology and other fundamental and applied biological problems [4,10].…”

Cell wall integrity signaling regulates cell wall regeneration via transcriptional activation inChlamydomonas reinhardtii

“…Earlier studies of cell wall-defective mutants exhibiting lysis upon NP-40 treatment categorized mutant phenotypes into three distinct groups: A) cells producing normal-looking walls attached to the plasma membrane, B) cells producing walls but not connected to the plasma membrane, and C) cells producing minute amounts of wall material 20,21,22 . These groups represent the three sequential consequences caused by g-lysin treatment: cracking the wall integrity, detaching the cell wall from the plasma membrane, and complete removal of the wall.…”