Macrocyst formation in three dictyostelid species, Dictyostelium monochasioides, Polysphondylium candidum, and P. pseudo-candidum

Abstract

Macrocyst formation in the sexual cycle was found in three dictyostelid species: Dictyostelium monochasioides, Polysphondylium candidum, and P. pseudo-candidum. Mating tests suggested that D. monochasioides and P. pseudocandidum were heterothallic and P. candidum was homothallic. The primary walls of macrocysts had partially or fully degenerated, while the inner walls, believed to be tertiary walls, showed an undulate structure.

A taxonomic revision of two dictyostelid species, Polysphondylium pallidum and P. album

“…Morphological observation and terminology.-Procedures of morphological observation followed Hagiwara (1989) and Kawakami and Hagiwara (2002). The subcultures of isolates were done with E. coli as food on nonnutrient agar plates to which a granular type of activated charcoal was added at 20 C under 12:12 h light:dark conditions.…”

“…Mating test.-The mating tests were performed according to the procedures described by Kawakami and Hagiwara (1999). Spores of each pair of strains were inoculated into small colonies of E. coli on 0.1% lactose/proteose peptone agar plates (6 cm diam).…”

“…In addition we reported that at least two heterothallic mating groups (i.e. groups A and B) were present in seven representative strains of P. pallidum (Kawakami and Hagiwara 2002). These two groups were clearly distinguished morphologically.…”

Two mating groups of Polysphondylium pallidum, a dictyostelid cellular slime mold

“…According to the procedures described by Kawakami and Hagiwara (1999), mating tests were performed as follows. Spores of each pair of strains were inoculated into small colonies (ϳ0.1 ml suspension poured) of Escherichia coli (Migula) Castellani et Chalmers as food on 0.1% lactose/ proteose peptone agar plates (6 cm in diameter).…”

“…We have considered that it is significant to introduce the biological species concept to the taxonomy of dictyostelids because their morphology is relatively simple and variable (Kawakami and Hagiwara 1999). Francis (1975Francis ( , 1980 first discovered the macrocysts of P. pallidum that were formed during the sexual cycle and showed that genetic exchange occurred in its macrocysts.…”