megamind

Several genomic locations for megamind homologues are possible in vertebrate genomes and many vertebrates have more than one homologous copy.

Three possible positions for megamind homolgoues have been identified:
(1) Antisense to birc6 intron, “(2) gene desert upstream of bdkrb1/,2 and (3) near hhipl1 homologs (found only in fish genomes)". All contain a conserved region near the 5’ of the final exon.

Zebrafish has expressed transcripts at all 3 loci, humans have (1) and (2).

Zebrafish linc-birc6: 2.4kb, 3 exons, alternative splicing. Antisense to intron of birc6. 5’ of last exon alignable and contains a highly conserved region.

Human (antisense birc6) - full length transcript has not been characterised, at least 2 exons, 5’ of second exon contains the highly conserved region.

Human LOC100507043 (upstream of BDKRB2) - ~3.2 kb, 2 exons, 5’ of second exon contains the highly conserved region.

Mouse 2810011L19Rik (upstream of BDKRB2) - 3.3 kb, 3 exons, 5’ of final exon contains the highly conserved region.

Linc-birc6 was most highly expressed of zebrafish megamind homolgoues. Expressed in zebrafish nervous system. Brain and eye at 24 hours post fertilization (hpf), brain only at 72 hpf.

Expressed in brain in mammals.

Linc-birc6 was required for normal embronyic brain development in Zebrafish. Morpholinos to decrease transcript level or block conserved site had brain and eye development defects.
- Lack of functional megamind at 48 hpf caused “smaller heads and eyes, enlarged brain ventricles (a hydrocephalic phenotype), and loss of NeuroD-positive cells in the retina and tectum.”

Defects could be recused by mature zebrafish megamind transcript (linc-birc6) as well as the mouse (AK012713, upstream of BDKRB2) and human (BX093813, antisense BIRC6) orthologues.

Conserved site was necessary, but not sufficient, to explain megamind function in zebrafish.

Has core highly conserved region in vertebrates of 93 nt. 15 of conserved nucleotides are T’s with 3 nt periodicity.