Transcriptome Sequencing and Assembly: Alaskan Samples
Tissue biopsies were obtained from two male bowhead whales harvested by
Inupiat hunters at Barrow, Alaska during the Fall hunt of 2010; heart, cerebellum,
liver, and testes were biopsied from male bowhead number 10B16,
and retina from male bowhead 10B20. Samples were immediately placed in
liquid nitrogen and transported in a dry shipper to Purdue University. RNA
was extracted using TRIZOL reagent (Invitrogen) following the manufacturer’s
protocol. RNA was purified using an Invitrogen PureLink Micro-to-Midi columns
from the Total RNA Purification System using the standard protocol.
RNA quantity and quality was estimated with a spectrophotometer (Nanodrop)
and by gel electrophoresis using an Agilent model 2100 Bioanalyzer. cDNA
libraries were constructed by random priming of chemically sheared poly A
captured RNA. Randomly primed DNA products were blunt ended. Products
from 450–650 bp were then isolated using a PippenPrep. After the addition
of an adenine to the fragments, a Y primer amplification was used to produce
properly tailed products. Paired-end sequences of 100 bp per end were generated
using the Illumina HiScan platform. Sequences with primer concatamers,
weak signal, and/or poly A/T tails were culled. The Trinity software package for
de novo assembly (Grabherr et al., 2011) was used for transcript reconstruction
(Table S1).