Characterisation of two novel types of hexactinomyxon spores (Myxozoa) with subsidiary protrusions on their caudal processes

Dis Aquat Organ. 2003 Jun 20;55(1):45-57. doi: 10.3354/dao055045.

Abstract

Two types of hexactinomyxon spores, Hexactinomyxon type 1 nov. and Hexactinomyxon type 2 nov., are reported from freshwater tubificid oligochaetes, Limnodrilus hoffmeisteri and L. udekemianus. Spores are triradially symmetrical and comprise a spore body, style and 6 caudal processes. The caudal processes arise from the division of each of the 3 valve cells into an equal pair of projections at the base of the style. One of each pair is fused conspicuously to its nearest neighbour for the initial 1/5 to 1/4 of their total length. Distally, each process possesses subsidiary protrusions which are irregularly distributed and irregularly shaped extensions of the valve cell. Scanning electron microscopy of Hexactinomyxon type 2 nov. revealed that these protrusions are a seamless extension of the valve cell wall which branch distally, occasionally laterally, and terminate in a distinct bulbous structure; they also form the terminus of each process. The small subunit ribosomal DNA gene (18S) of both hexactinomyxon types was amplified through a nested PCR, then digested with the restriction enzymes Dde I and Hha I. The resultant cleavage patterns suggested the presence of 2 forms. Subsequent partial sequencing of 18S rDNA confirmed the identification of 2 novel types.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • DNA, Protozoan / chemistry
  • DNA, Ribosomal / chemistry
  • Eukaryota / classification*
  • Eukaryota / genetics
  • Eukaryota / isolation & purification
  • Eukaryota / ultrastructure
  • Gene Amplification
  • Genotype
  • Microscopy, Electron, Scanning / veterinary
  • Oligochaeta / parasitology*
  • Phylogeny
  • Polymerase Chain Reaction / veterinary
  • Protozoan Infections, Animal
  • RNA, Ribosomal, 18S / genetics
  • Restriction Mapping / veterinary
  • Spores, Protozoan / genetics
  • Spores, Protozoan / ultrastructure

Substances

  • DNA, Protozoan
  • DNA, Ribosomal
  • RNA, Ribosomal, 18S