جستجوی مقالات مرتبط با کلیدواژه "tlr4" در نشریات گروه "کشاورزی"

This study was conducted to evaluate the TLR4 gene expression's pattern in ampulla and isthmus of dairy cows during the ovarian cycle. The ovarian cycle phase was determined based on the appearance, size, and color of corpus luteum and dominant follicle. The TLR4 expression was assessed in ampulla and isthmus of 40 oviducts using qRT-PCR. Results showed at the pre-ovulatory phase, TLR4 gene expression in the isthmus of ipsilateral oviducts was significantly greater than that in ampulla. Also, the expression of TLR4 in ampulla and isthmus of the oviducts ipsilateral to the pre-ovulatory ovary was significantly greater than that in the ampulla and isthmus of oviducts contralateral to the post-ovulatory or mid-cycle ovaries. In general, the present study showed that, TLR4 mRNA expression was differentially influenced by the stage of the ovarian cycle, its relation to the functional ovary, and the oviductal parts (ampulla or isthmus) in bovine.

I In this study, allelic polymorphism in candidate genes of TLR4 and IL2 involved in the immune system in four Iranian indigenous chickens were examined using PCR-RFLP technique. A total of 200 birds including common, West Azerbaijan, Marandi, Mazandarani indigenous chicken breeds were selected. For detection of mutation in TLR4 (257 bp) and IL2 (600 bp) genes the PCR products were digested by Sau96I and HphI restriction enzymes, respectively. Two alleles of C (138 and 119 bp) and G (119, 99 and 39 bp) and three genotypes of CC, CG and GG were identified in TLR4 marker site. Following the enzymatic digestion of the IL2 gene, two alleles of A (465, 64, 40 and 31bp) and B (454, 64, 40, 31 and 11 bp) and three genotypes of AA, AB and BB were identified. The whole populations was in Hardy-Weinberg equilibrium for TLR4 and IL2 marker sites. The calculated Shannon information index and fixation index values for TLR4 and IL2 marker sites was estimated to be (0.56 and 0.69) and (-0.05 and -0.10), respectively. The highest observed heterozygosity value for TLR4 and IL2 loci was estimated to be (0.55 and 0.40), respectively. Regarding to the existence of polymorphism in the studied loci and reduction of heterozygosity in these populations, the occurrence of non-random crosses can be prevented. This leads to an increase in heterozygosity and thus prevents the loss of genetic diversity in the populations would be. In the populations also, by studying the immune responses associated with these two loci, these sites can be used as suitable markers in breeding programs for increase of resistance to diseases in indigenous chickens.

To examine the possible role of maternal effect on progeny immune system development, the injection effects of the khazak yolk into the yolk of the commercial Ross egg on the performance, immunity and expression of TLR4 was determined in the commercial Ross chicken. For this purpose, 150 ROSS fertile eggs were randomly assigned to two experimental groups including group I (control-in ovo Ross yolk injection) and group II (in ovo khazak yolk injection) and were kept in incubator for 3 weeks. After incubation period, newly hatched chickens were fed with balanced ration for six weeks. Three Chickens from each experimental group were respectively killed at 27- and 42-d posthatch for analysis of immune organs weight (liver, burs and thymus), The HI anti- body titer levels and liver TLR4 mRNA expression levels. The results of Statistical analysis demonstrated that the in-ovo injection of khazak yolk into the Ross eggs not only significantly enhances growth rate and immune function but also decreases expression of TLR4 mRNA in the liver of treated group compared with the control group (P˂0.05). On the basis of these results it's possible that injection of khazak yolk into the Ross eggs at the first day of embryonic development enhances the chicken immune response at older ages.

The aim of the present study was to compare the expression of lactoferrin and TLR4 genes in cow milk somatic cells to investigate genetic differences effects and crossbreeding on the gene expression of the immune system as well as the effect of mastitis. Total RNA was extracted from fresh milk cells of 3 healthy Holstein¡ 3 Guilan Native and 3 F1 crossbred cattle belong to the National Animal Breeding Center of Iran and 3 Holstein with mild symptoms of clinical mastitis. After cDNA synthesis genes expression was measured using Real-time PCR relative to the reference gene GAPDH. The results showed while in crossbred cows the average expression of both genes was higher than parents (P0.05). This study indicated that while there was non-significance difference between Guilan native and Holstein¡ but the crossbreeding clearly affected on the expression of two genes associated with genetic resistance.

The TLR4 gene structure as the main receptor for lipopolysaccharide recognition of Gram-negative bacteria was investigated in two strains of Iranian commercial Arian line and west Azerbaijan native chicks and its expression was studied in some major organs. Blood samples of the 120 birds were taken and total DNAs extracted. Then، the target gene was sequenced using four pairs of primers on four samples of each strain. The effects of amino acid changes on protein function were assessed by PANTHER software. To investigate the gene expression، total RNAs were extracted from liver، spleen، and lung tissues after slaughter of the birds. Gene expression was assessed by semi-quantitative RT-PCR. The amplified RNAs from tissues of liver، spleen and lungs. Then electrophoresis images were processed with the ImageJ software and quantitative data analyzed by MINITAB. The results showed 3 new single polymorphisms (T1147C، C2246A and A1832G) in the sequence of TLR4 gene in the studied populations. The effects of variations on TLR4 protein structure indicated a deleterious effect of mutations on protein structure. The TLR4 gene expression in case of native and commercial strains did not show significant differences. Due to importance of the TLR4 in innate immunity and identification of some novel mutations affecting on protein structure، this gene could be a valuable candidate related to genetic resistance in poultry.

Mastitis is one of the most prevalent diseases of dairy cattle. In order to create genetic resistance to the disease, it is essential to identify resistant genes to mastitis. Toll-like receptors are the suitable candidate genes for enhancing genetic resistance to mastitis in Holstein cows. In this research, polymorphism of TLR4 gene’s promoter and its association with somatic cell count in a herd of Holstein cows in Isfahan was studied. For this purpose, DNA was extracted from 100 blood sample of Holstein cows. Two primers were used for amplifying the promoter of TLR4’s gene. These primers amplified 274bp fragments using polymerase chain reaction (PCR) method. The amplified fragments showed A and B genotypes with 0.74 and 0.26 frequency respectively. The results of this study showed that these two different genotypes have significant effect on somatic cell count in the studied herd (P<0/01). With respect to low heritability of somatic cell count (0.093) and deficiency of direct selection for improving of this characteristic, selection on the basis of TLR4 genotypes can efficiently used for increasing genetic resistance to mastitis.