The demonstration of acrasin in the later stages of the development of the slime mold Dictyostelium discoideum

✍ Scribed by Bonner, John Tyler

• Publisher: John Wiley and Sons
• Year: 1949
• Tongue: English
• Weight: 529 KB
• Volume: 110
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1401100206

✦ Synopsis

The amoeboid slime mold Dictyosteliwz discoideuin is well suited for the study of problems of development. I n its simple life cycle the processes of growth and cell multiplication are normally separated from the purely formative, morphogenetic processes. A capsule-shaped spore germinates and liberates a myxamoeba which when fed with suitable bacteria produces by successive binary fissions a mass of separate, independent myxamoebae. After a period this vegetative stage abruptly stops and the cells stream into central collection points (aggregation stage) and this transition is one from a growth phase to a morphogenetic phase. The cell mass, o r pseudoplasmodium, resulting from aggregation becomes elongate and moves as a cartridge-shaped body over the substratum for variable periods of time. When its forward motion ceases it turns upright into the air (culmination stage) and simultaneously differentiates into a thin, tapering stalk, a rounded apical spore mass or sorus, and a basal disc surrounding the base of the stalk. (See Raper, '35, '40a, '40b, '41, and Bonner, '44, for descriptive details.)

Good evidence has been given previously (Bonner, '4'7) to show that during aggregation the mpxamoebae are guided by chemotaxis towards the central mass, and the active, re-' Tt is not known if this is because each myxamoeba produres tlie same amount of arrasin and there are simply more niyxanioebae at the renter, or that for some reason the i~idiridual m?-xanioebae :it the center produce relatively more acrasin.

a The basir methods einployd here are the same as those described presiously (Bonner, '47).

a It was known, from tlie work of Yotts ('02) that Dicf!/oslelitrnt will go through its normal derelopinent undrr a layer of mineral oil. 'See Bonner ( ' 4 i ) for the iiiethod of preparation of the aggregating myxamoebae.