Evolution of a novel function: nutritive milk in the viviparous cockroach, Diploptera punctata.
Cockroach species show different degrees of maternal contribution to the developing offspring. In this study, we identify a multigene family that encodes water-soluble proteins that are a major component of nutritive "Milk" in the cockroach, Diploptera punctata. This gene family is associated with the evolution of a new trait, viviparity, in which the offspring receive nutrition during the gestation period. Twenty-five distinct Milk complementary DNAs were cloned and partially characterized. These complementary DNAs encode 22 distinct Milk peptides, each of length 171 amino acids, including a 16-amino acid signal peptide sequence. Southern blot analysis confirms the presence of multiple copies of Milk genes in D. punctata. Northern analysis indicates tissue- and stage-specific Milk gene expression. Examination of the deduced amino acid sequences identifies the presence of structurally conserved regions diagnostic of the lipocalin protein family. The shared exon/intron structure of one of the Milk loci with lipocalin genes further supports a close evolutionary relationship between these sequences.
Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242, USA.
Anna
A
Williford
Barbara
B
Stay
Debashish
D
Bhattacharya
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D015152:Blotting, Northern; D015139:Blotting, Southern; D003058:Cockroaches / Q000235:genetics* / Q000502:physiology*; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D040461:Gene Components; D019476:Insect Proteins / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D009943:Organophosphorus Compounds; D010802:Phylogeny; D012098:Reproduction / Q000502:physiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
C043517:2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinene 2-oxide; D018076:DNA, Complementary; D019476:Insect Proteins; D009943:Organophosphorus Compounds