Download Type-IV Antifreeze Proteins are Essential for Epiboly

International Journal Of Bilogical Sciences
Type-IV Antifreeze Proteins are Essential for Epiboly and
Convergence in Gastrulation of Zebrafish Embryos
Qing Xiao*, Jian-Hong Xia*,Xiao-Juan Zhang, Zhi Li, Yang Wang, Li Zhou, Jian-Fang Gui
Abstarc :
Many organisms in extremely cold environments such as the Antarctic Pole have evolved
antifreeze molecules to prevent ice formation. There are four types of antifreeze proteins (AFPs).
Type-IV antifreeze proteins (AFP4s) are present also in certain temperate and even tropical fish,
which has raised a question as to whether these AFP4s have important functions in addition to
antifreeze activity. Here we report the identification and functional analyses of AFP4s in
cyprinid fish. Two genes, namely afp4a and afp4b coding for AFP4s, were identified in gibel
carp (Carassius auratus gibelio) and zebrafish (Danio rerio). In both species, afp4a and afp4b
display a head-to-tail tandem arrangement and share a common 4-exonic gene structure. In
zebrafish, both afp4a and afp4b were found to express specifically in the yolk syncytial layer
(YSL). Interestingly, afp4a expression continues in YSL and digestive system from early
embryos to adults, whereas afp4b expression is restricted to embryogenesis. Importantly, we
have shown by using afp4a-specific and afp4b-specifc morpholino knockdown and cell lineage
tracing approaches that AFP4a participates in epiboly progression by stabilizing yolk
cytoplasmic layer microtubules, and AFP4b is primarily related to convergence movement.
Therefore, both AFP4 proteins are essential for gastrulation of zebrafish embryos. Our current
results provide first evidence that AFP such as AFP4 has important roles in regulating
developmental processes besides its well-known function as antifreeze factors.
Key Word :
antifreeze protein; yolk syncytial layer; epiboly; convergence; morphogenesis.
Volume 10, Number 7, - 2014 , ISSN 1449-2288