Evolution of a novel function: nutritive milk in the viviparous cockroach, Diploptera punctata

Evol Dev. 2004 Mar-Apr;6(2):67-77. doi: 10.1111/j.1525-142x.2004.04012.x.

Abstract

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Bayes Theorem
  • Blotting, Northern
  • Blotting, Southern
  • Cockroaches / genetics*
  • Cockroaches / physiology*
  • DNA, Complementary / genetics
  • Female
  • Gene Components
  • Insect Proteins / genetics*
  • Models, Genetic
  • Molecular Sequence Data
  • Multigene Family / genetics
  • Organophosphorus Compounds
  • Phylogeny*
  • Reproduction / physiology
  • Sequence Alignment
  • Sequence Analysis, DNA

Substances

  • 2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinene 2-oxide
  • DNA, Complementary
  • Insect Proteins
  • Organophosphorus Compounds