2. Materials and methods
2.1. Sample collection and total RNA extraction
The husbandry of alpacas and collection of their skin samples for use in described experiments were conducted in accordance with the International Guiding Principles for Biomedical Research Involving Animals (http://www.cioms.ch/index.php/texts-of-guidelines) and approved by Henan Normal University Council on Animal Care Guidelines. Three white and three brown healthy adult alpacas (Lama paco) were selected from the alpaca farm in Shanxi Agriculture University (Shanxi, China) for sample collection. Three pieces of skins (2 cm × 3 cm) were collected surgically from the hindquarters of each alpaca and immediately stored in liquid nitrogen. Total RNA from the samples was extracted using TRIzol reagent (Invitrogen, Carlsbad, CA, USA) according to the manufacturer's instructions. The RNA integrity was evaluated using gel electrophoresis and the RNA concentration was measured using a Nanodrop spectrophotometer an OD at 260 nm.