With the increasing interest in the identification of differences between camel breeds over the last decade, this study was conducted to estimate the variability of milk production and composition of four Saudi camel breeds during different seasons. Milk records were taken two days per week from females of Majahem, Safra, Wadha, and Hamra breeds distributed over Saudi Arabia. The milk yield during winter indicated that the weekly average of the Wadha breed was significantly lower (27.13 kg/week) than Majahem and Hamra breeds. The Safra breed had the lowest milk yield (30.7 kg/week) during summer. During winter, the Hamra breed had a lower content of all analyzed milk components except proteins and was characterized by a lower pH than the milk of the other breeds. However, the Hamra breed had significantly higher contents of milk fat and lactose than the other breeds during summer, with the corresponding values of 3.87 and 4.86%, respectively. Milk collected during winter from Majahem, Safra, and Wadha breeds was characterized by a significant increase in all milk components and milk pH. Finally, the isoelectric focusing analysis revealed noticeable variability of casein purified from camel milk within the different Saudi breeds, with the highest significant value of 2.29 g per 100 mL recorded for the Wadha breed.

This study is the first investigation for using sex-related gene expression in tail fin tissues of seabass as early sex determination without killing the fish. The European seabass (Dicentrarchus labrax) is gonochoristic and lacks distinguishable sex chromosomes, so, sex determination is referred to molecular actions for some sex-related genes on autosomal chromosomes which are well known such as cyp19a1a, dmrt1a, and dmrt1b genes which play crucial role in gonads development and sex differentiation. cyp19a1a is expressed highly in females for ovarian development and dmrt1a and dmrt1b are for testis development in males. In this study, we evaluated the difference in the gene expression levels of studied genes by qPCR in tail fins and gonads. We then performed discriminant analysis (DA) using morphometric traits and studied gene expression parameters as predictor tools for fish sex. The results revealed that cyp19a1a gene expression was significantly higher in future females’ gonads and tail fins (p ≥ 0.05). Statistically, cyp19a1a gene expression was the best parameter to discriminate sex even the hit rate of any other variable by itself could not correctly classify 100% of the fish sex except when it was used in combination with cyp19a1a. In contrast, Dmrt1a gene expression was higher in males than females but there were difficulties in analyzing dmrt1a and dmrt1b expressions in the tail because levels were low. So, it could be used in future research to differentiate and determine the sex of adult fish using the cyp19a1a gene expression marker without killing or sacrificing fish.

The Nile Tilapia (Oreochromis niloticus), a gonochoristic teleost fish with a XX/XY sex-determination system, is an ideal model for investigating gonadal sex differentiation. During gonadal differentiation, the expression of cyp19a1a in XX gonads and dmrt1 in XY gonads are required for undifferentiated tissues to develop into ovary or testis. In this study, quantitative real-time RT-PCR assessed the expression of cyp19a1a and dmrt1 genes in gonads and tail fin tissues. Differences in gene expression mean among sexually differentiated fish were analyzed using two-way analysis of variance (ANOVA) and validation of mixed model using discriminant analysis (DA) for morphometric traits and the gene expression in gonads and tail fin tissues used to validate and utilize them in discriminating sexes in sex-differentiated Nile Tilapia fish. The results revealed that, cyp19a1a gene expression in female ovaries was more significant than dmrt1 in male testis. In the other hand, the dmrt1 gene expression in the tail fin was higher in males than females. Both, cyp19a1a and dmrt1 genes, can discriminate fish sexes by 100% by using their expression in tail fin tissues. In conclusion, the cyp19a1a and dmrt1 genes could be used as a genetic marker to discriminate between the Nile Tilapia sexes, whereas used as an indicator for ovarian or testis differentiation in sexually differentiated Nile Tilapia using tail fin tissues. It is worth mentioning that this is the first investigation for using cyp19a1a and dmrt1 genes from Nile Tilapia tail fin tissues in sex determination.

Goats were raised in different regions of the world for various purposes including milk and meat production as well as skin and fiber. The number of goats evaluated to be about 2.5 million heads, which represent about 30% of total meat income of Saudi Arabia. Saudi local goat breeds did not receive the required attention about their genetic information, despite their important adaptive characteristics. This study aims to access genetic diversity of some Saudi goat breeds depending on sequence analysis of specific mitochondrial D-loop region. Results showed that the Saudi goats resemble two main groups (1 and 2). Group one, is classified into two subgroups. Subgroup 1a (Saudi goats with accession numbers MG725669, MG725670 and MG725673 of Habsi breed) and Subgroup 1b (Saudi goats with accession numbers MG725674, MG725676 and MG725677 of Harri breed). Lineage A (group one), showed characteristic difference compared to all other studied goat members around the world. The nearest goat to this Lineage is goat accession number (KJ940969). On the other hand, Saudi goats outside this group (group 2) showed high similarity with other sequences of goats obtained from GenBank database, which included in this study. The results of Lineage 2 (group 2) showed no noticed sharp difference with the published GenBank database sequences. Finally, Lineage 1(group one) showed novel results including specific SNPs and one deletion, which is characteristic only to this group. This will give more insights about correlation between sequence, classification and function of these breeds. Key words: Mitochondrial D-loop, Phylogenetic study, Saudi goat breeds