PMID- 14561635 OWN - NLM STAT- MEDLINE DCOM- 20040203 LR - 20081015 IS - 0950-1991 (Print) IS - 0950-1991 (Linking) VI - 130 IP - 24 DP - 2003 Dec TI - Posterior patterning genes and the identification of a unique body region in the brine shrimp Artemia franciscana. PG - 5915-27 AB - All arthropods share the same basic set of Hox genes, although the expression of these genes differs among divergent groups. In the brine shrimp Artemia franciscana, their expression is limited to the head, thoracic/trunk and genital segments, but is excluded from more posterior parts of the body which consist of six post-genital segments and the telson (bearing the anus). Nothing is currently known about the genes that specify the identity of these posterior structures. We examine the expression patterns of four candidate genes, Abdominal-B, caudal/Cdx, even-skipped/Evx and spalt, the homologues of which are known to play an important role in the specification of posterior structures in other animals. Abdominal-B is expressed in the genital segments of Artemia, but not in the post-genital segments at any developmental stage. The expression of caudal, even-skipped and spalt in the larval growth-zone suggests they may play a role in the generation of body segments (perhaps comparable with the role of gap and segmentation genes in insects), but not a direct role in defining the identity of post-genital segments. The expression of caudal at later stages suggests a role in the specification of anal structures. A PCR screen designed to isolate Hox genes expressed specifically in the posterior part of the body failed to identify any new Hox genes. We conclude that the post-genital segments of Artemia are not defined by any of the genes known to play a role in the specification of posterior segments in other arthropods. We argue that these segments constitute a unique body region that bears no obvious homology to previously characterised domains of Hox gene activity. FAU - Copf, Tijana AU - Copf T AD - Institute of Molecular Biology and Biotechnology (IMBB-FORTH) Vouton, 71110 Iraklio Crete, Greece. FAU - Rabet, Nicolas AU - Rabet N FAU - Celniker, Susan E AU - Celniker SE FAU - Averof, Michalis AU - Averof M LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20031015 PL - England TA - Development JT - Development (Cambridge, England) JID - 8701744 RN - 0 (Drosophila Proteins) RN - 0 (Homeodomain Proteins) RN - 0 (Transcription Factors) RN - 0 (eve protein, Drosophila) SB - IM MH - Amino Acid Sequence MH - Animals MH - Artemia/*anatomy & histology/genetics/*growth & development MH - Body Patterning/*genetics MH - Drosophila Proteins MH - *Genes, Homeobox MH - Homeodomain Proteins/genetics/*metabolism MH - Molecular Sequence Data MH - Morphogenesis/physiology MH - Sequence Alignment MH - Transcription Factors/genetics/metabolism EDAT- 2003/10/17 05:00 MHDA- 2004/02/05 05:00 CRDT- 2003/10/17 05:00 PHST- 2003/10/17 05:00 [pubmed] PHST- 2004/02/05 05:00 [medline] PHST- 2003/10/17 05:00 [entrez] AID - dev.00835 [pii] AID - 10.1242/dev.00835 [doi] PST - ppublish SO - Development. 2003 Dec;130(24):5915-27. doi: 10.1242/dev.00835. Epub 2003 Oct 15.