TY - GEN
T1 - Partial characterization and biological activity of a metamorphic inducer of the dorid nudibranch Adalaria proxima (Gastropoda: Nudibranchia)
AU - Lambert, WD
AU - Todd, Christopher David
AU - Hardege, JD
N1 - Invertebrate Biology
PY - 1997
Y1 - 1997
N2 - Larval metamorphosis of the dorid nudibranch Adalaria proxima is induced by a water-borne cue present in seawater that has been conditioned with live Electra pilosa, its preferred bryozoan prey. Extracts and fractions of Electra-conditioned seawater (CSW) were assessed in bioassays of competent larvae to further elucidate the nature of the inductive chemical cue. Extracts of volatile compounds and lipids present in CSW did not induce metamorphosis; the fractions of CSW remaining after extraction still retained the inducer. Heating CSW to 80 degrees C for 5 min did not eliminate the inductive cue, but metamorphic activity was decreased after boiling CSW for 5 min. No larvae metamorphosed in treatments in which CSW was incubated with trypsin or protease before bioassay. Larvae metamorphosed in CSW after centrifugation, filtration (0.22 mu m), and treatment with a bactericide. Metamorphosis was induced by ultrafiltrates (10 kDa, 1 kDa, and 500 Da) of CSW, albeit in a variable manner. Up to 45% of larvae metamorphosed in the 500 Da and 1 kDa fractions. There was little response by larvae to the 10 kDa fraction. These procedures eliminated volatile organic molecules, lipids, and large proteins as potential molecules inducing metamorphosis of larvae of A. proxima. Furthermore, that treatment of CSW with trypsin eliminated the inductive cue and that metamorphosis occurred in ultrafiltrates of CSW strongly suggests that larvae of A. proxima respond to a small (<500 Da) arginine- or lysine-containing peptide.
AB - Larval metamorphosis of the dorid nudibranch Adalaria proxima is induced by a water-borne cue present in seawater that has been conditioned with live Electra pilosa, its preferred bryozoan prey. Extracts and fractions of Electra-conditioned seawater (CSW) were assessed in bioassays of competent larvae to further elucidate the nature of the inductive chemical cue. Extracts of volatile compounds and lipids present in CSW did not induce metamorphosis; the fractions of CSW remaining after extraction still retained the inducer. Heating CSW to 80 degrees C for 5 min did not eliminate the inductive cue, but metamorphic activity was decreased after boiling CSW for 5 min. No larvae metamorphosed in treatments in which CSW was incubated with trypsin or protease before bioassay. Larvae metamorphosed in CSW after centrifugation, filtration (0.22 mu m), and treatment with a bactericide. Metamorphosis was induced by ultrafiltrates (10 kDa, 1 kDa, and 500 Da) of CSW, albeit in a variable manner. Up to 45% of larvae metamorphosed in the 500 Da and 1 kDa fractions. There was little response by larvae to the 10 kDa fraction. These procedures eliminated volatile organic molecules, lipids, and large proteins as potential molecules inducing metamorphosis of larvae of A. proxima. Furthermore, that treatment of CSW with trypsin eliminated the inductive cue and that metamorphosis occurred in ultrafiltrates of CSW strongly suggests that larvae of A. proxima respond to a small (<500 Da) arginine- or lysine-containing peptide.
KW - metamorphosis
KW - larval induction
KW - Mollusca
KW - CREPIDULA-FORNICATA L
KW - GREEN SEA-URCHIN
KW - FREE FATTY-ACIDS
KW - SAND DOLLAR
KW - STRONGYLOCENTROTUS-DROEBACHIENSIS
KW - DENDRASTER-EXCENTRICUS
KW - GREGARIOUS SETTLEMENT
KW - LARVAL METAMORPHOSIS
KW - PARTIAL-PURIFICATION
KW - PHESTILLA-SIBOGAE
UR - http://www.scopus.com/inward/record.url?scp=0031488560&partnerID=8YFLogxK
M3 - Other contribution
VL - 116
ER -