The platypus is an egg-laying mammal. Its eggs hatch 10 days after being laid, a

Question

The platypus is an egg-laying mammal. Its eggs hatch 10 days after being laid, after developing in utero for 28 days. One of its genes. Cbl1. encodes cystathionine-beta-lyase. which is used to make methionine. Describe a method that you could use to see if the level of Cbl1 mRNA in eggs changes between 0. 5. and 10 days after being laid. How could you determine if any change is due to altered activity of the gene's promoter (more initiation events), or altered rates of degradation of the mRNA in the older eggs? What controls would you need for these experiments? When nuclei are treated with DNAse 1. the DNA is converted into a ladder. If the same experiment is done on Histone H1-depleted chromatin, the size of the steps on the ladder are reduced by about 10 nt. Why?

Explanation / Answer

Tropical theileriosis is a major protozoan disease of cattle and is associated with high rates of morbidity and mortality. Indigenous cattle (Bos indicus) are less affected by this disease than exotic and crossbred cattle. Genetic basis of resistance to tropical theileriosis in indigenous cattle is not well studied. Recent reports suggest that number of immune response genes expressed differentially in exotic and indigenous breeds play an important role in breed specific resistance to tropical theileriosis. Such studies comparing expression of these genes in crossbred cattle and indigenous cattle are lacking. The present study compares the mRNA expression of immune-related genes in response to Theileria annulata infection in indigenous and crossbred cattle. Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples of indigenous (Tharparkar) and crossbred (HF/BS/Jersey × Hariana) cattle and challenged with prepared ground-up tick supernatant carrying Theileria annulata sporozoites in vitro. qPCR was employed to measure relative mRNA expression of toll-like receptor 10 (TLR10), signal-regulatory protein alpha (SIRPA), MHC class II DQ (BoLA-DQA), musculoaponeurotic fibrosarcoma (MAF) and prion protein (PRNP) genes in infected and control PBMCs from crossbred and indigenous cattle. On the basis of comparative fold change analysis, significant up-regulation in SIRPA, PRNP and MHC DQ genes and significant down-regulation in TLR10, cMAF and MAFB genes in crossbreds as compared to indigenous cattle was observed. Results of the present study suggest that breed specific differential expression of the genes under study may contribute to the breed specific resistance to Theileria annulata infection in indigenous cattle compared to crossbred cattle.

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