Artificial Parthenogenesis in Starfish Eggs: Production of Parthenogenetic Development Through Suppression of Polar Body Formation by Methylxanthines

Abstract

Methylxanthines such as caffeine, theophylline, and theobromine at 6 to 10 mM activated eggs of the starfish, Asterina pectinifera. Up to one hour of methylxanthine treatment induced parthenogenetic development in more than 80% of the eggs that failed to form the second polar body. Eggs that formed two polar bodies did not cleave. Compared with normally fertilized eggs the first cleavage in parthenogenetically developing eggs was delayed by 2 h in eggs lacking a polar body, and by 3 h in eggs with one (first) polar body. The intervals between successive cleavages were identical to those of normally fertilized eggs.Examination of the chromosome number revealed that most parthenogenetic embryos develop as tetraploids. The possible significance of centriolar material in initiating parthenogenetic development is suggested.

Parthenogenetic development of dwarf surf dam,Mulinia lateralis, oocytes treated with polar body suppressing agents

“…The relative effectiveness of the three treatments probably relates to mechanisms of action, e.g., inhibition of microfilament formation [CB (Schatten and Schatten,198 I)] or spindlelkinetochore attachment [heat, caffeine (Zinkowski et al, 1989)l. All have been used successfully to inhibit polar body formation in other bivalve molluscs (Durand et al, 1990;Gosling and Nolan, 1989;Longo, 1972;Obata and Nemoto, 1984;Stanley et al, 1981). The dose of CB used for this study was lower than that typically used by other investigators (0.5 pglml vs 1 -10 pglml).…”

“…Oocytes were activated by the addition of sperm (i.e., fertilized) or potassium ions (KC1-activated, 1 volume of 0.52 M KC1 to 9 volumes of oocyte suspension) (Allen, 1953;Dube and Guemer, 1982) and rinsed of excess sperm or KC1 after an 8 min exposure. Four methods were employed to suppress polar body formation: cytochalasin B (Allen, 1987), caffeine (Obata and Nemoto, 1984), heat shock (Gosling and Nolan, 1989), and combined caffeinelheat shock (Durand et al, 1990). Oocytes were cultured for 20-24 h following experimental treatments, and the percentage of Dstage and abnormal larvae were recorded.…”

“…Parthenogenesis has been induced in various marine invertebrates such as the sea cucumber, Holothuria leucospilota (Maruyama, 1981), sea star, Asterina pectinifera (Obata and Nemoto, 1984), sea urchin, Lytechinus pictus (Brandriff et al, 1975), and marine echiuroid worm, Urechis caupo (Tyler, 1931(Tyler, , 1932. In the sea star parthenogenesis proceeded with a tetraploid genome.…”

Centrosome destined to decay in starfish oocytes

“…2E) were used for the electric fusion process. It is known that a normally matured egg with both PB1 and PB2 will not cleave even after activation without sperm, indicating the absence of reproductive centrioles (Obata and Nemoto, 1984;Washitani-Nemoto et al, 1994;Tamura and Nemoto, 2001;Uetake et al, 2002).…”

“…Artificial parthenogenesis in starfish was pioneered in the early 1980s by Obata and Nemoto (Obata and Nemoto, 1984) and later, Washitani-Nemoto et al (Washitani-Nemoto et al, 1994) found that suppression of polar body (PB) extrusions in artificially activated oocytes induces parthenogenetic development, whereas eggs that matured normally did not develop, even with artificial activation. They suggested that the meiotic centrosomes retained in the eggs by the failure of PB extrusion are diverted to mitosis-organizing centers in the mitotic spindle, resulting in parthenogenetic development.…”