MODERN GENETICS JOURNAL (MGJ)
Year:2007 | Volume:2 | Issue:3|Papers Count:8

Bacillus thuringiensis is a gram positive bacterium with a great agronomic and scientific interest. Most of the subspecies of this bacterium colonize and cause death in a large variety of host insects and even nematodes, but each strain does so with a high degree of specificity. This is mainly determined by the arsenal of crystal proteins that the bacterium produces during speculation. In this review, we describe the properties of these toxin genes and proteins and the current knowledge of the basis for their specificity.

Down syndrome (DS) is the most common chromosomal abnormality clinically associated with mental retardation and affects approximately 1 per 800 live births. It stems from the failure of chromosome 21 to segregate normally during maternal miosis in 95% of cases. and very small proportion of cases due to postzygotic mitotic non-disjunction or robertsonian translocation. Abnormal folate metabolism due to common polymorphisms in folate metabolism gene has been described as possible cause of trisomy 21. In this study,we analyzed the relationship between 2756A>Gpolymorphism in methionine synthase (MTR) gene, a key enzyme in folic acid pathway producing methionine from homocysteine, and trisomy 21 in Iranian mothers having a Down syndrome child. 2756 A>G polymorphism cause A>G transition at 2756bp, converting aspartic acid into glycine. We have studied 93 mothers with DS children and 116 control mothers in this study. Human genomic DNA was isolated from blood samples with salting out procedure. The MTR 2756 A>G was identified using PCR followed by restriction enzyme digestion of amplified products. Prevalence of 2756 A>G polymorphism was investigated in both case and control mothers group. The frequency of different genotype among case group were AA in 56 (60.2%) AG in 33 (35.5%) and GG in 4 (4.3%) mothers. Whereas they were 56%, 35.3% and 10% among control mother group respectively. Statistical analysis showed no association between 2756A>G polymorphism in methionine syntheses and risk of Down syndrome in Iranian population.

The purpose of this study was to estimate genetic and phenotypic parameters for egg weight, yolk weight and yolk compositions in a commercial broiler line. From 110 hens at 32 weeks of age with known pedigree, 220 eggs (2 eggs from each hen) were collected. Eggs were weighed and yolk quality traits (containing, yolk weight and yolk fatty acids) were recorded. Yolk fatty acids were determined with Gas Chromatography. Covariance components and genetic parameters were estimated using a multiple traits animal model with DFREML program. Estimates of heritability varied from 0.48 (for palmitoleic acid) to 0.69 (for estearic acid). Additive genetic correlations between yolk weight with palmetic, palmitoleic, estearic, oleic and linoleic acid amounts were 0.64, 0.30, 0.49, 0.71 and 0.02, respectively. Genetic correlations between fatty acids varied from 0.44 (between palmitoleic and estearic acids) to 0.96 (between estearic and oleic acids). For phenotypic correlations, estimates varied from 0.51 (between palmitoleic acid with estearic and linoleic acids) to 0.94 (between estearic and oleic acids). The high heritability of yolk fatty acids indicated that they can be improved by selection. Because of high and positive genetic correlation between yolk weight and fatty acid amounts, selection on the basis of yolk weight may improve yolk fatty acids.

Twining, a trait associated with prolificacy in sheep, has long been recognized of economic importance which is usually expressed in a binary mode and discrete phenotypic distribution. For analysis of twining in a given population, usual statistical methods which are based upon normality distribution of the variable cannot be used but instead generalized linear models should be applied. In order to study 'some environmental factors (year of lambing, dam age and lamb birth weight) affecting on twining and to estimate phenotypic trend a total of 5100 birth records belonging to 1681 ewes lambing from 1984 to 2003 in a large flock of Baluchi sheep breed in Abbasabad breeding station of Mashhad were used. Only the records of singles and twins were used in this study. The average ewe age and birth weight of lambs were 2.79 years and 4.25 Kg respectively. Twining information was analysed by a logistic regression using GENMOD procedure of SAS programmed. The results obtained showed that year of lambing, dam age at lambing and lamb birth weight had statistical significant effects on the probability of twining. The probability of twining had a positive correlation with dam age while it was negatively correlated with lamb birth weight suggesting that birth weight of individual lambs born from twin-lambing ewes is expected to be lower than single-lambing ewes. The results also revealed a positive significant phenotypic trend for the probability of twining over the period of20 years which was estimated to be 0.01 per year of lambing.

Calpastatin gene was recognized as candidate gene for growth rate and meat quality. In order to study polymorphism of calpastatin gene, blood was randomly collected from 100 Sistani cows in Zehak Research Station. The DNA extraction was based on Boom method.The digestion of PCR product for CASTI by MspI restriction enzyme revealed two alleles, allele M with 2 fragments of 286 & 336 bp and N which didn't digested. The data analyzed by PopGene32 software .The MM, MN and NN genotypes for calpastatin gene frequencies were 51.86, 32.27 and 4.87 respectively. The level of hetrozygosity was low that it seems related to the calpastatin gene achieved in herd which was studied which is the result of herd been closed. Such that in the herd breeding system, sires have been often used in reproduction herd system. Besides, according to statistics analyze, it was found out that MM genotype had the best performance in ages 0- 3 ,9 -12 month for average gain weight and Dunkan test showed that there is a meaning full difference(p<0.05) between MN,NN genotypes on weight in ages 0- 3 and 9- 12 month and this shows the effect of calpastatin gene on growth.Out data shows that the population is in hardy-win berg equilibrium. With attention the role of a calpastatin in meat tenderness, it seems that this gene can be use as marker- assisted selection on meat tenderness.

Aegilops tauschii is an herbage, diploid and autogamous plant that is origin of D genome in Triticum aestivum. In this research, karyotypic characters in populations of Aegilops tauschii collected from different provinces of Iran were studied (7 and 3 populations related to Aegilops tauschii and Aegilops strangulata, respectively). For cultivation seeds were plated on filter paper to produce root tips. Selected roots with 1.5 - 2.5 cm length were used for slide preparation from root tips. Chromosomal traits including: length of short arm and long arm, total length of chromosome, relative length of chromosome and arm ratio were measured. A. tauschii and A. strangulata were diploid and their base chromosome numbers were 7. Karyotypic formula in these populations was metacentric and submetacentric. According to Al and TF%, population 840 relative to A. strangulate had more asymmetric chromosomes. Also population 641 relative to A. tauschii had the symmetric chromosomes and the other populations had an average level in respect of symmetry. No relationship was observed between clustering and geographical regions of populations. A. tauschii and A. strangulata did not differ from chromosomal number and indices, because they did not locate in distinct groups by cluster analysis.

Rapeseed is one of the important oil seed crop in the world. Rapeseed has been improved for agronomical and economical traits via genetic engineering. The best gene transformations to rapeseed has been done through Agrobacterium tumeifaciens (with different strains) method. In this research, the effect of rapeseed B.napuscultivar, explants and Agrobacterium tumefactions strain has been studied on the gus reporter genes transformation.The experimental design was factorial based on completely randomized design with four replications. The gus reporter genes was cloned in pBI121 as a plant expression vector. The pBI121 plasmid containing gus gene was transferred to rapeseed via A. tumeifaciens (LBA4404 and C58 (pGV3101) strains) mediated transformation method. Putative transgenic shoots generated from cotyledons and hypocotyls of 2 commercial cultivars of B. napus (pF-7045 -91 and SLM-046). The transformed plants were screened on MS medium containing 25 mgL-1 kanamycin. Presence and expression of the reporter gene in plants were confirmed by PCR technique and gus assay. Statistical analysis of data showed that there are significant different between rapeseed cultivars, explants, A. tumeifa ciens strains and their interactions for transgenesis. The PF -7045 -91 genotype with 10.64% average was better than from SLM-046 variety with 4.5% average. Therefore "LBA4404 strain of A. tumefactions with 8.79% frequency in transformation was better than from C58 (pGV3101) with 6.39%.