Adenylate kinase in sea urchin embryonic cilia.
Sea urchin embryos swim by ciliary movement. Hypertonic shock causes deciliation and loss of motility. Within 2-4 h, cilia regenerate and the embryos swim again. Regeneration of cilia occurs multiple times. The adenylate kinase (AK) activity of isolated cilia was studied. A 130-kDa Sp-AK isozyme, present in sperm flagella, is also present in embryonic cilia. AK activity is responsible for approximately 93% of nonmitochondrial ATP regeneration from ADP in embryonic cilia. This is unlike sea urchin sperm flagella, where approximately 31% of the nonmitochondrial ATP regeneration is from the 130-kDa Sp-AK isozyme and approximately 69% from the flagellar creatine kinase (Sp-CK). Embryos were deciliated 1-3 times and after a 2-h period of regeneration the major ciliary axonemal proteins such as the tubulins appeared constant in amount. However, a moderate decrease in ATPase activity, and a large decrease of total AK activity, were measured. The decrease in AK activity paralleled the decrease in embryo swimming velocity. Embryos were deciliated once and cilia regeneration followed for 4 h. ATPase activity recovered to control levels by 3 h, but AK activity and swimming velocity remained lower than in controls. Detergent solubility data and kinetic experiments indicate that, in addition to the 130-kDa Sp-AK, there is at least one additional AK isozyme in embryonic cilia. Analysis of the S. purpuratus genome indicates five AK isozymes in addition to the 130-kDa Sp-AK isozyme. Decreased swimming velocity of embryos with regenerated cilia suggests that regenerated cilia are not as functionally perfect as naturally grown cilia.
Kinukawa
Masashi
M
Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0202, USA. makinukawa@ucsd.edu
Vacquier
Victor D
VD
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000263:Adenylate Kinase / Q000378:metabolism*; D000818:Animals; D002465:Cell Movement / Q000502:physiology; D002923:Cilia / Q000201:enzymology*; D003402:Creatine Kinase / Q000378:metabolism; D005407:Flagella / Q000502:physiology; D008297:Male; D013094:Spermatozoa / Q000201:enzymology; D047270:Strongylocentrotus purpuratus / Q000196:embryology / Q000201:enzymology* / Q000235:genetics
D003402:Creatine Kinase; D000263:Adenylate Kinase; D000251:Adenosine Triphosphatases