Selection of Housekeeping Genes for Real-time Fluorescence Quantitative RT-PCR in Skin of Fine-wool Sheep

Development of cerebral mitochondrial respiratory function is impaired by thyroid hormone deficiency before birth in a region-specific manner

Thyroid hormones regulate adult metabolism partly through actions on mitochondrial oxidative phosphorylation (OXPHOS). They also affect neurological development of the brain, but their role in cerebral OXPHOS before birth remains largely unknown, despite the increase in cerebral energy demand during the neonatal period. Thus, this study examined prepartum development of cerebral OXPHOS in hypothyroid fetal sheep. Using respirometry, Complex I (CI), Complex II (CII), and combined CI&CII OXPHOS capacity were measured in the fetal cerebellum and cortex at 128 and 142 days of gestational age (dGA) after surgical thyroidectomy or sham operation at 105 dGA (term ~145 dGA). Mitochondrial electron transfer system (ETS) complexes, mRNA transcripts related to mitochondrial biogenesis and ATP production, and mitochondrial density were quantified using molecular techniques. Cerebral morphology was assessed by immunohistochemistry and stereology. In the cortex, hypothyroidism reduced CI-linked respiration and CI abundance at 128 dGA and 142 dGA, respectively, and caused upregulation of PGC1α (regulator of mitochondrial biogenesis) and thyroid hormone receptor β at 128 dGA and 142 dGA, respectively. In contrast, in the cerebellum, hypothyroidism reduced CI&II- and CII-linked respiration at 128 dGA, with no significant effect on the ETS complexes. In addition, cerebellar glucocorticoid hormone receptor and adenine nucleotide translocase (ANT1) were downregulated at 128 dGA and 142 dGA, respectively. These alterations in mitochondrial function were accompanied by reduced myelination. The findings demonstrate the importance of thyroid hormones in the prepartum maturation of cerebral mitochondria and have implications for the etiology and treatment of the neurodevelopmental abnormalities associated with human prematurity and congenital hypothyroidism.

Expression of cytokine genes at tick attachment and control sites of Namaqua Afrikaner, Dorper and South African Mutton Merino sheep

Cytokines are immune response components important in innate immunity and inflammatory response. They are harnessed as part of local immunological responses by animals to combat local infections and/or infestations. This study investigated expression of four selected cytokine genes, namely, interleukin 1 beta (IL-1β), chemokine C-C ligand 2 (CCL2), chemokine C-C ligand 26 (CCL26) and interleukin 8 (IL-8), at tick attachment and control sites in a South African indigenous sheep breed the Namaqua Afrikaner (NA) and two commercial breeds, the Dorper and South African Mutton Merino (SAMM). The NA was previously shown to be more resistant to infestation by ticks than the two commercial breeds. NA ewes expressed IL-1β more at tick attachment sites compared to Dorpers. The NA breed was also more likely to upregulate the expression of the CCL2, CCL26 and IL-8 genes at tick attachment sites compared to control sites than the other breeds. The results of this study gave an indication that cytokines are involved in immune responses to tick challenge and laid a foundation for further studies under controlled challenge conditions.