It has been demonstrated that ACSL3 and ACSL5 play important roles in fat metabolism. To investigate the primary functions of ACSL3 and ACSL5 and to evaluate their expression levels during goose fatty liver development, we cloned the ACSL3 and ACSL5 coding domain sequences (CDSs) of geese using RT-PCR and analyzed their expression characteristics under different conditions using qRT-PCR. The results showed that the goose ACSL3 (JX511975) and ACSL5 (JX511976) sequences have high similarities with the chicken sequences both at the nucleotide and amino acid levels. Both ACSL3 and ACSL5 have high expression levels in goose liver. The expression levels of ACSL3 and ACSL5 in goose liver and hepatocytes can be changed by overfeeding geese and by treatment with unsaturated fatty acids, respectively. Together, these results indicate that ACSL3 and ACSL5 play important roles during fatty liver development. The different expression characteristics of goose ACSL3 and ACSL5 suggest that these two genes may be responsible for specific functions.

The objective of the current research was to investigate the pattern of subcutaneous adipose tissue growth during Peking duck (Anas platyrhynchos) early development and to determine the reasons for regional differences. The morphological characteristics in 5 regions of subcutaneous tissue, including the neck area (NSF), chest area (CSF), lower abdomen area (ASF), back area (BSF), and leg area (LSF), were analyzed by comparing the morphology of the sections, adipocyte volume and number, and lipid content from wk 1 to 8. Moreover, the mRNA expression of several molecular marker genes, including 47-kDa tail interacting protein (TIP47), adipose differentiation-related protein (ADRP), and perilipin, were detected from wk 1 to 8 using quantitative real-time PCR. Our results revealed that the average cell number declined greatly as fattening proceeded (except in the NSF) and changed very little after wk 4 in all 5 regions. In contrast, the average cell volume and triglyceride content per cell increased gradually during early duck growth. The BSF and LSF lipid content had a different pattern of change than the other regions. The NSF, CSF, and ASF regions had the highest lipid content values at all stages, the BSF was intermediate, and the LSF was the lowest at all weeks except wk 3. The highest TIP47 expression level was found in the NSF from wk 1 to 2 and BSF at wk 1. The relative expression level of TIP47 was higher in the CSF than in the ASF and BSF at wk 4, and was higher in the NSF than in the ASF at wk 6. The highest levels of ADRP and perilipin were detected in the LSF. These results suggest that a combination of adipocyte hyperplasia and hypertrophy is mainly responsible for the development of duck adipose tissue before wk 4, after which adipose expansion is accomplished by adipocyte hypertrophy only. Adipocyte hyperplastic and hypertrophic capacity, fat storage capacity, and metabolic activity may be partial explanations for the regional differences during duck growth.

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