High impact information on hoxa1a

• To compare the relative importance of Hox genes during fin versus limb morphogenesis, we cloned zebrafish (Danio rerio) HoxD and HoxA complex genes and analysed their expression during fin development [1].
• Molecular evolution of the HoxA cluster in the three major gnathostome lineages [2].
• HoxA cluster noncoding sequences conserved between bichir and euteleosts indicate that novel cis-sequences were acquired in the stem actinopterygians and maintained after cluster duplication [3].
• We aligned (PipMaker) the nucleotide sequences of the HoxA clusters of tilapia, pufferfish, striped bass, zebrafish, horn shark, human, and mouse, which are separated by approximately 500 million years of evolution [4].
• We observed novel expression patterns in the midbrain, such that zebrafish hoxa1a and hoxc1a are expressed anterior to the domain traditionally thought to be under Hox patterning control [5].

Biological context of hoxa1a

• The expression pattern of zebrafish hoxa1a mRNA during embryonic development was studied [6].
• Expression studies, carried out with HoxD and HoxA genes, showed that all vertebrates use the same general scheme, involving the colinear activation of gene expression in both space and time [7].
• This phenotype correlated with a reduction in hoxa1 expression during gastrulation [8].

Anatomical context of hoxa1a

• Herein, we show that hoxa1a mRNA is expressed in the ventral region of both the midbrain and anterior hindbrain during the developmental period from the pharyngula to the protruding-mouth stages via whole-mount in situ hybridization [6].
• The main difference in HoxA gene expression between fin and limb development is that in tetrapods (with the exception of newts) Hoxa-11 expression is suppressed by Hoxa-13 in the distal limb bud mesenchyme [9].
• There is striking evidence of a similar pattern of homologous regulatory gene expression (eg Shh, and Hox A & D genes) in tetrapod limb buds, and both similarity and differences when these are compared with expression patterns in a teleost fish paired fin bud [10].

Other interactions of hoxa1a

• The observed temporal and spatial distributions of zebrafish hoxa1a mRNA differ greatly from the expression patterns of zebrafish hoxb1a and hoxb1b paralagous genes [6].
• The previously described expression patterns of zebrafish and mouse Hoxa1 genes are seemingly very disparate, with mouse Hoxa1 expressed in the gastrula stage hindbrain and the orthologous zebrafish hoxa1a gene expressed in cell clusters within the ventral forebrain and midbrain [11].

References