A Microarray-Based Analysis Reveals that a Short Photoperiod Promotes Hair Growth in the Arbas Cashmere Goat

Abstract

Many animals exhibit different behaviors in different seasons. The photoperiod can have effects on migration, breeding, fur growth, and other processes. The cyclic growth of the fur and feathers of some species of mammals and birds, respectively, is stimulated by the photoperiod as a result of hormone-dependent regulation of the nervous system. To further examine this phenomenon, we evaluated the Arbas Cashmere goat (Capra hircus), a species that is often used in this type of research. The goats were exposed to an experimentally controlled short photoperiod to study the regulation of cyclic cashmere growth. Exposure to a short photoperiod extended the anagen phase of the Cashmere goat hair follicle to increase cashmere production. Assessments of tissue sections indicated that the short photoperiod significantly induced cashmere growth. This conclusion was supported by a comparison of the differences in gene expression between the short photoperiod and natural conditions using gene chip technology. Using the gene chip data, we identified genes that showed altered expression under the short photoperiod compared to natural conditions, and these genes were found to be involved in the biological processes of hair follicle growth, structural composition of the hair follicle, and the morphogenesis of the surrounding skin appendages. Knowledge about differences in the expression of these genes as well as their functions and periodic regulation patterns increases our understanding of Cashmere goat hair follicle growth. This study also provides preliminary data that may be useful for the development of an artificial method to improve cashmere production by controlling the light cycle, which has practical significance for livestock breeding.

Fig 1. Photograph of white Arbas Cashmere goat and paraffin sections of Cashmere goat skin stained with hematoxylin & eosin.

A. Photograph of a white Arbas Cashmere goat. B. Longitudinal section of goat skin sampled during the short photoperiod (anagen phase). C. Longitudinal section of goat skin sampled during the natural photoperiod (pro-anagen phase). The black arrows indicate the primary hair follicles (PHFs) and secondary hair follicles (SHFs) in the samples. Scale bars: 500 μm.

Fig 2. Hierarchical cluster analysis of the data from the different skin samples of goats raised under short and natural photoperiods.

The color legend is at the bottom of the Fig Red indicates the genes with greater expression relative to the geometric means, and green indicates the genes with lower expression relative to the geometric means. T1, T2, and T3 represent the 3 samples of side skin from goats raised under the short photoperiod, and C1, C2, and C3 represent the 3 samples of skin from goats raised under the natural photoperiod.

Fig 3. GO classifications for the differentially expressed genes.

Differentially expressed genes enriched in the following GO terms are indicated: biological processes, cellular components, and molecular function.

Fig 4. qPCR validation of the expressed genes.

For the 3 randomly selected differentially expressed genes, the fold changes of the genes in the short and natural photoperiods were assessed by qPCR (red bar) and compared to those detected in the gene chip microarray (black bar). All Ct values were normalized to GAPDH, and replicates (n = 3) of each sample were run. The P values (T-test) of the Q-PCR data are 0.1096 (keratin 34), 0.0003 (MLN), and 0.0201 (CYP1A1).