Edit in JSFiddle 

$('input.mygene_query_target').genequery_autocomplete({
    "species": "human,mouse,rat",
    "limit": 10,
    "gene_label": "{symbol}: {name} ({species})",
    "select": function(event, ui) {
        alert( ui.item ?
              "Selected: " + ui.item.label + '('+ui.item._id+')':
              "Nothing selected, input was " + this.value);
    }
});

External resources loaded into this fiddle:

<body class="ui-widget">
    <label for="gene_query">Enter a gene here:</label>
    <input id="gene_query" style="width:250px" class="mygene_query_target">
</body>