dictyNews
Electronic Edition
Volume 40, number 25
October 3, 2014

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=========
Abstracts
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Induction of macrocyst wall formation by ZYG1 in Dictyostelium 
discoideum

Aiko Amagai1*, Fumio Takahashi1,2,3, Toshinori Usui4, 5, 
Tomoaki Abe4 and Yasuo Maeda1

1Graduate School of Life Sciences, Tohoku University, 
Sendai 980-8577, Japan
2PRESTO, Japan Science and Technology Agency, Kawaguchi, 
Saitama 332-0012, Japan, 
3Present address: Department of Biotechnology, College of Life 
Sciences, Ritsumeikan University, Nojihigashi, Kusatsu, 
Shiga 525-8577, Japan
4Department of Biological Sciences, Faculty of Science and 
Engineering,  Ishinomaki Senshu University, Ishinomaki, 
Miyagi 986-0031, Japan
5Present address: Tohoku Medical Megabank Organization, 
2-1 Seiryo-Machi Aoba-ku, Sendai 980-8574, Miyagi, Japan


Research J of Devel. Biol., accepted

Background: Macrocyst is known as the sexual developmental 
form in cellular slime molds. ZYG1 is known to be involved 
in zygote formation by cell fusion during macrocyst formation 
in Dictyostelium mucoroides, one of the species of cellular 
slime molds. 

Aim and methods: To know the effects of ZYG1 on the asexual 
and sexual development in Dictyostelium discoideum, an another 
species of cellular slime molds, we observed the developmental 
process and forms of a transformant (GFP-ZYG1OE) derived from 
Dictyostelium discoideum, in which GFP-ZYG1 fusion protein is 
overproduced. 

Results: GFP-ZYG1OE cells were developed without or with an 
opposite mating type, V12M2 cells. When GFP-ZYG1OE cells 
were developed without V12M2 cells, they formed macrocyst-like 
structures consisting of a central cell mass and a thick 
transparent macrocyst wall surrounding it. It was suggested 
that transparent zones in the macrocyst wall were formed by 
cell fusion. When GFP-ZYG1OE cells were developed with 
V12M2 cells, globular bodies which are likely the macrocysts 
surrounded by thin cellulosic walls were found besides 
macrocysts. They were formed directly from zygotic giant cells 
without the formation of cell aggregates. The formation of the 
globular body is not caused by ZYG1 overproduction, because 
GFPCONT cells, a transformant overproducing GFP protein as 
controls, also formed globular bodies.

Conclusion: By the use of GFP-ZYG1OE cells overproducing 
GFP-ZYG1 fusion protein, it is revealed that ZYG1 is closely 
involved in macrocyst wall formation. This is the new finding 
concerning the function of ZYG1. In addition, the formation 
of a globular body, which is likely the macrocyst surrounded 
by a thin cellulosic wall, is demonstrated as a novel process 
of sexual development.

Submitted by Aiko Amagai [aimagai@amber.plala.or.jp]
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[End dictyNews, volume 40, number 25]