Two examples of a non-miRbase registered miRNA identified using our miRNAminer web-server. (A) Human miR-764 was identified using miRbase mouse miR-764 sequence as input (and default parameters) for miRNAminer search. The output reported a homolog (presumably hsa-miR-764), which is located in the second intron of human serotonin receptor 2C (HTR2C; NM 000868). The mouse miRNA homolog is located in an intron of the same gene (HTR2C; NM 008312) suggesting an evolutionary conserved co-expression of miRNA and its host gene [27-29]. High conservation is seen in this region (mountain-like graph derived from UCSC Genome Browser 17 species multiZ alignment; ). Black rectangles represent exons (shorter rectangles in C are UTRs), lines are introns and dark-grey rectangles are miRNA genes. (B) RNA secondary structure of both the identified human (top) and mouse (bottom) miR-764 exhibit similar thermodynamic stability (41.8/49.9 kcal/mol, respectively) and structures (mature miRNA region is underlined). Human miR-764 homolog was also identified by Berezikov . (C) Non-registered (miRbase) human miR-763 is highly conserved among vertebrate species and can potentially bind its own host gene. On top; a schematic non-scaled representation of the HMGA2 transcript (NM 003483; human miR-763 is in dark-grey; conservation plot as shown in A). Expressed Sequence Tags (ESTs; light-grey bars) are evidence for the expression of this particular genomic region. ESTs from top to bottom: BM715067 (isolated from eye-related tissue); BJ997562 (isolated from wilms tumor tissue); BU39975 (isolated from eye-related tissue); AI935081 (tissue source unknown). On the right; the potential binding site of miR-763 in HMGA2 3'UTR (nt 2–8 of the miRNA; positions 2192–2198) is conserved to human, mouse and rat.