ABSTRACT
This
study was designed to assess genetic diversity of TLR7 gene and its expression
profile in the Nigerian indigenous chickens and ISA Brown layer chicken. The
study population comprises eight (8) groups (naked neck, normal and
frizzled-feathered Nigerian indigenous chickens in rain forest and Guinea
Savannah regions respectively, Fulani ecotype chicken and ISA Brown layer
chicken). Five (5) blood samples were collected from each chicken group.
Genomic DNA was isolated from each blood sample using the Zymo Quick-gDNATM
Miniprep kit. The DNA sequencing of chTLR7 gene was done using the Sanger
Sequencing Chemistry. Tissues from the thymus and the liver were aseptically
collected from Two (2) clinically healthy chickens from each chicken group and
were immediately transferred into separate 1.5 ml Eppendorf tubes containing 1
ml of RNALater solution. Total RNA was isolated using ISOLATE II RNA Mini kit.
Complementary DNA (cDNA) was synthesized using SensiFASTTM cDNA
synthesis kit. The expression of chTLR7 RNA was determined by qPCR assay;
β-actin was used as the reference gene. 26 SNPs, two deletions and two
insertions in the intronic region of TLR7 gene in the Nigerian indigenous
chicken population and ISA Brown commercial layer chicken were found. Haplotype
analysis revealed 13 haplotypes out of which nine (9) were unique to the
Nigerian indigenous chickens; three (3) haplotypes were shared between ISA Brown
layer chicken and the Nigerian indigenous chickens, while one (1) haplotype was
unique to the Red jungle fowl. Nucleotide diversity estimates ranged from 0 to
0.019, which were close to zero and suggest that the chicken populations were
not genetically differentiated at TLR7 locus. Estimates of gene flow ranged
from -0.096 to 0.400 and were close to zero. Genetic distance estimates ranged
from 0.007 to 0.054 and were close to zero, which suggests that the chickens
have a close ancestor. The estimates of nearest-neighbour statistic ranged from
0.227 to 0.714, which showed that the chicken populations were part of the same
panmictic population, hence were not genetically differentiated (P>0.05) at
the TLR7 locus. Phylogenetic analysis of TLR7 gene sequences of the genetic
groups and the Red jungle fowl revealed very close relationship at the TLR7
locus, which suggests that the TLR7 locus is highly conserved. TLR7 expression
in the liver and thymus was significantly different (P<0.01) among the eight
chicken groups; the Nigerian indigenous chickens expressed more TLR7 gene than
ISA Brown layer chicken. Rain forest naked neck chicken had significantly
(P<0.01) highest TLR7 expression of 2.07±0.07 fold. However, expression of
TLR7 gene in the liver of rain forest frizzle-feathered and normal chicken,
Guinea savannah naked neck, frizzle-feathered and normal chicken, and Fulani
ecotype chicken were similar (P>0.05). Gene expression analysis of TLR7 RNA
suggests that the Nigerian indigenous chickens could have comparatively more
antiviral immune response than ISA Brown commercial layer chicken, hence could
be used to develop chickens lines with good antiviral response. Polymorphisms
observed at TLR7 gene in the Nigerian indigenous chickens could be used in
marker-assisted selection to produce chicken lines with good antiviral
response.
HENRY, O (2022). Genetic Diversity And Expression Profile Of Tlr7 Gene In The Nigerian Indigenous Chickens And Isa Brown Commercial Layer Chicken. Mouau.afribary.org: Retrieved Sep 08, 2024, from https://repository.mouau.edu.ng/work/view/genetic-diversity-and-expression-profile-of-tlr7-gene-in-the-nigerian-indigenous-chickens-and-isa-brown-commercial-layer-chicken-7-2
OKECHUKWU, HENRY. "Genetic Diversity And Expression Profile Of Tlr7 Gene In The Nigerian Indigenous Chickens And Isa Brown Commercial Layer Chicken" Mouau.afribary.org. Mouau.afribary.org, 14 Nov. 2022, https://repository.mouau.edu.ng/work/view/genetic-diversity-and-expression-profile-of-tlr7-gene-in-the-nigerian-indigenous-chickens-and-isa-brown-commercial-layer-chicken-7-2. Accessed 08 Sep. 2024.
OKECHUKWU, HENRY. "Genetic Diversity And Expression Profile Of Tlr7 Gene In The Nigerian Indigenous Chickens And Isa Brown Commercial Layer Chicken". Mouau.afribary.org, Mouau.afribary.org, 14 Nov. 2022. Web. 08 Sep. 2024. < https://repository.mouau.edu.ng/work/view/genetic-diversity-and-expression-profile-of-tlr7-gene-in-the-nigerian-indigenous-chickens-and-isa-brown-commercial-layer-chicken-7-2 >.
OKECHUKWU, HENRY. "Genetic Diversity And Expression Profile Of Tlr7 Gene In The Nigerian Indigenous Chickens And Isa Brown Commercial Layer Chicken" Mouau.afribary.org (2022). Accessed 08 Sep. 2024. https://repository.mouau.edu.ng/work/view/genetic-diversity-and-expression-profile-of-tlr7-gene-in-the-nigerian-indigenous-chickens-and-isa-brown-commercial-layer-chicken-7-2