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The South African Mutton Merino (SAMM), a dual‐purpose (meat and wool) sheep breed, is characterized by its excellent performance on growth, carcass traits and meat quality compared to other fine‐wool Merino breeds. Nowadays, the SAMM breed has been widely used to cross with commercial and indigenous fine‐wool or coarse‐wool breeds to improve the growth and meat performance in many countries. To date, however, little is known about the genetic basis for its prominent characteristics. In this study, whole‐genome sequences of 10 SAMM were sequenced and the selection signatures were analyzed together with those of 39 Australian Merino and Chinese Merino (wool‐type Merino) by FST, iHS, and XP‐EHH methods. In total, 313 genes in 277 regions were identified by at least 2 methods with the signal of selection and 21 of them were identified by all three methods. We highlighted a list of interesting genes, including GHR, LCORL, SMO, NCAPG, DCC, IBSP, PPARGC1A, PACRGL, PRDM5, XYLB, AHCYL2, TEFM, AFG1L, and FAM184B, which have been shown to be involved in growth, carcass traits, and meat quality by previous studies. Herein, GHR, encoding a transmembrane receptor for growth hormone, is the most notable one. We report the first study on selection signatures analysis of SAMM at whole‐genome sequence level. These results provide new insights into the genetic mechanisms underlying the growth and carcass traits in SAMM.

Syndiotactic polypropylene (s-PP) was prepared by metallocene catalyst and was fractionated with the temperature rising elution fractionation (TREF) technique. The nonisothermal behavior of the obtained fractions was investigated. Fractions was first cooled at different rates and then heated at a constant rate. The parameters such as the peak crystallization temperature (T c ), the onset crystallization temperature (T on ), the difference between T on and T c (⌬T 1 ϭ T on Ϫ T c ), the crystallization enthalpy (⌬H), the peak melting temperatures (T m1 , T m2 ), and the difference between the T m1 and T m2 (⌬T 2 ϭ T m2 Ϫ T m1 ) were obtained. The dependence of these parameters on cooling rate, syndiotacticity, and molecular weight was discussed. It is found that T c , T on , ⌬H, T m1 , and T m2 systematically increase with increasing syndiotacticity and are depressed on increasing the cooling rate. Cooling rate, syndiotacticity, and molecular weight show different influences on ⌬T 1 . In the melting process of s-PP, double peaks were observed.

It is well known that Dorper (DP) is a full-bodied, fast-growing and high dressing percentage breed, while the production performance of Small-tailed Han sheep (STH) is not so excellent, in contrast to DP. Therefore, in this study, a comparative transcriptomic analysis of liver and muscle tissues from DP and STH breeds was carried out to find differentially expressed genes (DEGs) that affect their growth and meat quality traits. The results showed that the total number of DEGs was 2,188 in the two tissues. There were 950, 160 up-regulated and 1,007, 71 down-regulated genes in the liver and muscle, respectively. Several DEGs such as TGFB1, TGFB3, FABP3, LPL may be associated with growth and development in DP. Also, several GO terms were found to be associated with muscle growth and development, such as developmental growth (GO:0048589), and myofibril (GO:0030016). Further validation of eight genes (6 up-regulated, and 2 down-regulated) was performed using quantitative RT-PCR. These findings will provide valuable information for studying growth and development as well as meat quality traits in sheep.

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