Phospholipase Czeta mRNA expression and its potency during spermatogenesis for activation of quail oocyte as a sperm factor.
This study was conducted to investigate the role of a sperm-borne compound in oocyte activation in special reference to the time when oocyte activation is required by testicular cells during spermatogenesis in quail. First, effects of a microinjection of quail sperm extract (SE) and quail phospholipase Czeta (PLCzeta) cRNA into quail oocytes were assessed by observation of pronuclear formation and cytoplasmic segmentation, respectively. Secondly, the effects of a microinjection of round spermatids with or without PLCzeta cRNA into quail oocytes were studied by observation of development. When the oocytes were injected with SE at 0.13 mg protein/ml, both pronuclear formation and cytoplasmic segmentation were optimally induced. However, pronuclear formation was blocked when SE was pretreated with heat or when the oocyte was pretreated with BAPTA (a Ca(2+) chelator) before SE injection. On the other hand, when the oocytes were injected with PLCzeta cRNA at 60 microg/ml, not only pronuclear formation but also cytoplasmic segmentation were optimally induced. However, PLCzeta cRNA-induced pronuclear formation was blocked by pretreatment with cycloheximide (an inhibitor of protein synthesis) or with BAPTA. Most interestingly, round spermatids alone cannot induce blastodermal development but microinjection of a round spermatid with PLCzeta cRNA can induce development. In addition, RT-PCR revealed that PLCzeta mRNA is expressed in elongated spermatids and testicular sperm but not in round spermatids. It is concluded that PLCzeta is a functional sperm factor for oocyte activation to initiate resumption of meiotic division in quail and its potency is acquired after elongated spermatid formation during the spermatogenesis.
Mizushima
Shusei
S
Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan. smizushima@aoni.waseda.jp
Takagi
Soichi
S
Ono
Tamao
T
Atsumi
Yusuke
Y
Tsukada
Akira
A
Saito
Noboru
N
Shimada
Kiyoshi
K
D000818:Animals; D002118:Calcium / Q000378:metabolism; D005260:Female; D005306:Fertilization / Q000502:physiology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D054801:Phosphoinositide Phospholipase C / Q000235:genetics / Q000378:metabolism; D011784:Quail; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism
D007527:Isoenzymes; D012333:RNA, Messenger; D054801:Phosphoinositide Phospholipase C; D002118:Calcium