Related to zebrafish. The Ostariophysi. We sampled six members of the Ostariophysi including 3 cypriniformes and 3 non-cypriniformes. Phenotype associated with HoxA13a knockdown in zebrafish. Two examples of cypriniformes and their yolk sac extentions:.
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We sampled six members of the Ostariophysi including 3 cypriniformes and 3 non-cypriniformes.
Phenotype associated with HoxA13a knockdown in zebrafish
Two examples of cypriniformes and their yolk sac extentions:
Normal Zebrafish larva with yolk sac extension phenotype
Loss of phenotype when HoxA13a is knocked down
Return of phenotype when HoxA13a is artificially restored
Carasius auratus larvae
Danio rerio larvae
Sampled Fish Species
Chanos chanos— a milk fish
Ictalurus punctatus— channel catfish
Yolk sac extension
Yolk sac extension
Misgurnus anguilicaudatus— dojo loach
Carassius auratus— common goldfish
Gyrinocheilus sp.— Chinese algae eater
A comparison of HoxA13 sequences in Cypriniformes and other closely related species
By Emily Edenburn
Teacher, East Rock Global Magnet School, 8
7th Grade Science
Question: How do novel characteristics arise and what changes in genes cause them to occur?
I focused on a novel character that is putatively specific to Cypriniformes--the yolk sac extension. I hope to identify novel sequences might be associated with this group.
The purpose of this study was to evaluate sequence divergence in duplicated HoxA13 genes in zebrafish and identify amino acid sites that may be associated with the YSE.
Hox grenes are a family of genes that affect body plan features during larval development. These genes show evolutionary importance because they are highly conserved across taxa.
Scientists have been able to remove and then replace Hox genes in animals, including zebrafish. The following shows what happens when Hox A13a is removed and then replaced in Danio rerio.
These six species of fish were chosen because they are representative of the main groups within the Ostariophysi.
We compared our HoxA13 sequences with the published HoxA13 sequences of the zebrafish Danio rerio- a member of the Cypriniformes
This specific sampling of fish will allow us to see what sequences are novel to cypriniformes and are not shared among the other closely related taxa
I sequenced the Hox A13b paralogs in the milkfish (Chanos chanos) and the dojo loach (Misgurnus anguilicaudatus).
When compared with sequences from the Chinese algae eater, (Gyrinocheilus sp.) electric knifefish (Apteronotus sp.), andgoldfish (Carassius sp.), we identified >15 amino acid sites that may be associated with a novel character in Cypriniformes-the YSE!
HoxA13aamino acid sequences unique to Cypriniformes
What does Hox A13 do?
vertebrates. The yolk sac extension (YSE) is a distal body
A13a and A13b paralogs
Kenji Saitoh, Masaki Miya, Jun G. Inoue, Naoya B. Ishiguro, Mutsumi Nishida, “Mitochondrial Genomics of Ostariophysan Fishes: Perspectives on Phylogeny and Biogeography, “ J of Molecular Evolution, 56:4, 2003, p 464-472