A method of screening for genes of major effect.

نویسندگان

  • B P Kinghorn
  • B W Kennedy
  • C Smith
چکیده

This paper describes a method for screening animal populations on an index of calculated probabilities of genotype status at an unknown single locus. Animals selected by such a method might then be candidates in test matings and genetic marker analyses for major gene detection. The method relies on phenotypic measures for a continuous trait plus identification of sire and dam. Some missing phenotypes and missing pedigree information are permitted. The method is an iterative two-step procedure, the first step estimates genotype probabilities and the second step estimates genotypic effects by regressing phenotypes on genotype probabilities, modeled as true genotype status plus error. Prior knowledge or choice of major locus-free heritability for the trait of interest is required, plus initial starting estimates of the effect on phenotype of carrying one and two copies of the unknown gene. Gene frequency can be estimated by this method, but it is demonstrated that the consequences of using an incorrect fixed prior for gene frequency are not particularly adverse where true frequency of the allele with major effect is low. Simulations involving deterministic sampling from the normal distribution lead to convergence for estimates of genotype effects at the true values, for a reasonable range of starting values, illustrating that estimation of major gene effects has a rational basis. In the absence of polygenic effects, stochastic simulations of 600 animals in five generations resulted in estimates of genotypic effects close to the true values. However, stochastic simulations involving generation and fitting of both major genotype and animal polygenic effects showed upward bias in estimates of major genotype effects. This can be partially overcome by not using information from relatives when calculating genotype probabilities-a result which suggests a route to a modified method which is unbiased and yet does use this information.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Functional Screening of Phosphatase-Encoding Genes from Bacterial Sources

Phosphatase (APase) enzymes including phytases have broad applications in diagnostic kits, poultryfeeds, biofertilizers and plant nutrition. Because of high levels of sequence diversity among phosphatases,an efficient functional screening method is a crucial requirement for the isolation of the encodinggenes. This study reports a functional cloning screening method for the iso...

متن کامل

شناسایی ژن های عمده صفات وزن یک‌روزگی و شش‌هفتگی در یک لاین تجاری گوشتی با استفاده از روش تفرق بیزی

At the present study in order to detect major genes in a commercial broiler line Bayesian method as the most powerful statistical method in detection of major genes was used. After preliminary data editing, data of body weight (BW) at birth and six weeks of age of 14 and 35 generations respectively were analyzed using iBay software. The results verified segregation of major gene for two economi...

متن کامل

Screening for Causative Mutations of Major Prolificacy Genes in Iranian Fat-Tailed Sheep

Objective The presence of different missense mutations in sheep breeds have shown that the bone morphogenetic protein receptor 1B (BMPR1B), bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9) genes play a vital role in ovulation rate and prolificacy in ewes. Therefore, the present study investigates BMPR1B, BMP15 and GDF9 genes mutations in prolific ewes of Iranian ...

متن کامل

مطالعه بررسی بیان ژن های KRAS و NRAS افراد مبتلا به سرطان ریه نسبت به گروه سالم

Background: Lung cancer is one of the most common cancers around the world, and a major cause of death. The KRAS and NRAS genes could cause malfunction in signal transduction and cell cycle regulation. Materials and Methods: In this study, the expression level of KRAS and NRAS biomarkers among 50 lung cancer patients in comparison with 50 normal individuals was investigated. Total RNA from blo...

متن کامل

اثر عصاره سیر بر بیان ژن‌های iNOSو IFNγ در رده سلولی J774 آلوده به لیشمانیا ماژور

  Background and Objectives : The protozoa of leishmania lead to cutaneus and visceral leishmaniasis. Activation macrophages phagocyte parasites and this mechanism can be done with production of active radicals oxygen and nitric oxide, That is done through immunomodulator , as a basic process for production of the new drug. In this study, the effect of garlic extract as an immunomodulator on J7...

متن کامل

ردیابی ژن های عمده برای برخی از صفات اقتصادی مرغان بومی استان یزد با استفاده از روش های مختلف آماری

 At the present study, the observations of performance traits including body weight at 8 and 12 weeks of age, age at sexual maturity, egg weight and egg number were analyzed to detect major genes in Yazd native fowl. The probability of segregation for major genes was studied using simple tests including tests of normality, Bartlett, Levene and Fain for residuals and Bayesian analysis. Segregati...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • Genetics

دوره 134 1  شماره 

صفحات  -

تاریخ انتشار 1993