Identification of Candidate Genes for Pigmentation in Camels Using Genotyping-by-Sequencing.

The coat color of dromedary is usually uniform and varies from black to white, although dark- to light-brown colors are the most common phenotypes. This project was designed to gain knowledge on novel color-related variants using genotyping-by-sequencing (GBS). The association between the SNPs and coat color was tested using MLM (mixed linear models) with kinship matrix. Three GWAS models including white color vs. non-white color, black vs. non-black color, and light-brown vs. dark-brown color were performed. There were no distinct genetic clusters detected based on the color phenotypes. However, admixture occurred among all individuals of the four different coat color groups. We identified nine significant SNPs associated with white color after Bonferroni correction, located close to ANKRD26, GNB1, TSPYL4, TEKT5, DEXI, CIITA, TVP23B, CLEC16A, TMPRSS13, FXYD6, MPZL3, ANKRD26, HFM1, CDC7, TGFBR3, and HACE1 genes in neighboring flanking regions. The 13 significant SNPs associated with black color and the candidate genes were: CAPN7, CHRM4, CIITA, CLEC16A, COL4A4, COL6A6, CREB3L1, DEXI, DGKZ, DGKZ, EAF1, HDLBP, INPP5F, MCMBP, MDK, SEC23IP, SNAI1, TBX15, TEKT5, TMEM189, trpS, TSPYL4, TVP23B, and UBE2V1. The SNAI1 gene interacted with MCIR, ASIP and KIT genes. These genes play a key role in the melanin biosynthetic and pigmentation biological process and melanogenesis biological pathway. Further research using a larger sample size and pedigree data will allow confirmation of associated SNPs and the identified candidate genes.

Genomic prediction for growth using a low-density SNP panel in dromedary camels.

For thousands of years, camels have produced meat, milk, and fiber in harsh desert conditions. For a sustainable development to provide protein resources from desert areas, it is necessary to pay attention to genetic improvement in camel breeding. By using genotyping-by-sequencing (GBS) method we produced over 14,500 genome wide markers to conduct a genome- wide association study (GWAS) for investigating the birth weight, daily gain, and body weight of 96 dromedaries in the Iranian central desert. A total of 99 SNPs were associated with birth weight, daily gain, and body weight (p-value < 0.002). Genomic breeding values (GEBVs) were estimated with the BGLR package using (i) all 14,522 SNPs and (ii) the 99 SNPs by GWAS. Twenty-eight SNPs were associated with birth weight, daily gain, and body weight (p-value < 0.001). Annotation of the genomic region (s) within ± 100 kb of the associated SNPs facilitated prediction of 36 candidate genes. The accuracy of GEBVs was more than 0.65 based on all 14,522 SNPs, but the regression coefficients for birth weight, daily gain, and body weight were 0.39, 0.20, and 0.23, respectively. Because of low sample size, the GEBVs were predicted using the associated SNPs from GWAS. The accuracy of GEBVs based on the 99 associated SNPs was 0.62, 0.82, and 0.57 for birth weight, daily gain, and body weight. This report is the first GWAS using GBS on dromedary camels and identifies markers associated with growth traits that could help to plan breeding program to genetic improvement. Further researches using larger sample size and collaboration of the camel farmers and more profound understanding will permit verification of the associated SNPs identified in this project. The preliminary results of study show that genomic selection could be the appropriate way to genetic improvement of body weight in dromedary camels, which is challenging due to a long generation interval, seasonal reproduction, and lack of records and pedigrees.

Genome-Wide Diversity, Population Structure and Demographic History of Dromedaries in the Central Desert of Iran.

The development of camel husbandry for good production in a desert climate is very important, thus we need to understand the genetic basis of camels and give attention to genomic analysis. We assessed genome-wide diversity, linkage disequilibrium (LD), effective population size (Ne) and relatedness in 96 dromedaries originating from five different regions of the central desert of Iran using genotyping-by-sequencing (GBS). A total of 14,522 Single Nucleotide Polymorphisms (SNPs) with an average minor allele frequency (MAF) of 0.19 passed quality control and filtering steps. The average observed heterozygosity in the population was estimated at 0.25 ± 0.03. The mean of LD at distances shorter than 40 kb was low (r2 = 0.089 ± 0.234). The camels sampled from the central desert of Iran exhibited higher relatedness than Sudanese and lower than Arabian Peninsula dromedaries. Recent Ne of Iran's camels was estimated to be 89. Predicted Tajima's D (1.28) suggested a bottleneck or balancing selection in dromedary camels in the central desert of Iran. A general decrease in effective and census population size poses a threat for Iran's dromedaries. This report is the first SNP calling report on nearly the chromosome level and a first step towards understanding genomic diversity, population structure and demography in Iranian dromedaries.

Effect of pennyroyal, savory and thyme essential oils on Japanese quail physiology.

An experiment was conducted to show the effects of different levels of pennyroyal, thyme and savory essential oils dietary supplementation on performance, organs weight, intestinal morphology, and serum lipids in quails. A total of 550 day-old Japanese quail chicks were allocated into 11 dietary treatments of 5 replications (10 birds in each cage) under a randomized experimental design. The treatments were a basal diet (Control), or 3 levels (200, 300, and 400 ppm) of thyme essential oil (TO), or 3 levels (200, 300, and 400 ppm) of savory essential oil (SO), or 3 levels (200, 300, and 400 ppm) of pennyroyal essential oil (PO) added separately to the basal diet, or also the basal diet supplemented with 100 ppm of flavophospholipol. Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured weekly and calculated totally for 35 d. The organs weight and morphology of intestine parts of one bird from each cage were measured on 35 d. At the same day, blood samples were collected and cholesterol and triglyceride values were separately determined for male and female quails. Although the addition of different levels of essential oils in quail's diet did not affect BWG, a significant decline in FI was observed in the group supplemented with 400 ppm of TO. At the same time, FCR significantly improved (P < 0.05) in the same group as well as in the group supplemented with the antibiotic. However, the organs weight was not significantly affected by the experimental treatments. Nevertheless, villi height of duodenum, jejunum and ileum was significantly increased and crypt depth was significantly decreased in the quails fed diets supplemented with different levels of TO and SO. The values of serum triglycerides decreased in both sexes in the groups that received diets supplemented with different levels of essential oils whereas the values of cholesterol decreased only in males of the essential oils supplemented groups. From the present observations it can be concluded that thyme and savory essential oils can improve FCR by decreasing FI through boosting the absorption of nutrients in intestine. These plant essential oils can replace antibiotic growth parameters without having any adverse effect on quail's health with thyme essential oil exerting the most effective activity.