Number Of Inbreds Research Articles

Massese sheep characteristics and demo-genetic trends in the province of Pisa (Italy)

Preserving animal breeds is key to a country’s economy, environment and culture. The present study collects all the available information on the Massese sheep breed and analyzes their demo-genetic trends in Pisa since 1976. Data were provided by Asso.Na.Pa. Descriptive statistics were analysed using Jmp software. The pedigree parameters of a total of 10,393 animals (whole population-WP) were analyzed using CFC, ENDOG and Pedigree viewer software. Animals born in the last fifteen years represented the Reference Population (RP), while animals with one or two unknown parents constituted the Base Population (BP). Demographic results showed an inconstant trend of offspring registration in the Herd book with two periods of a dramatic decline in lamb registrations and a substantially short productivity with a mean number of registered newborns of 1.5 and 18.2 for ewes and rams, respectively. A total of 6456 animals represented the RP, of which only 1059 animals (16.4%) had both known parents. The BP consisted of 7156 animals, thus highlighting the lack of sire and dam registration which prevented an accurate evaluation of the genetic parameters. The average inbreeding coefficient in the WP was 0.78%, and 0.046% in the RP. The number of inbreds was 575 in the WP and 17 in the RP. The present study represents a tool for breeders and technicians aimed at conserving and exploiting the genetic resources of Massese sheep through efficient breeding plans.

How Many Parents Give the Highest Yield in Predicted Synthetic and Composite Populations of Maize?

Some U.S. farmers are still interested in open‐pollinated (OP) maize (Zea mays L.), but most varieties are low yielding. How would one develop high‐yielding OP varieties, and what are their commercial prospects? To answer this question, we analyzed data from published diallel experiments using Wright's equation. There were seven diallels with inbreds and 14 with populations. The number of inbreds needed to form high yielding synthetics was on average from five to eight lines. The highest predicted yields for composites were on average with three to seven populations. The potential of synthetics and composites as OP varieties in the USA has not been fully examined, though these would probably not be economical for grain in the U.S. Corn Belt. However, their yields may show improvement over current OP varieties and they may be commercially viable in some limited circumstances.

Serial Analysis of Zein by Isoelectric Focusing and Sodium Dodecyl Sulfate Gel Electrophoresis

Zein, the major storage protein of maize (Zea mays L.) endosperm, was extracted from a number of inbreds with alcohol plus a reducing agent. Isoelectric focusing (IEF) separated total zeins into 41 components, while sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) separated total zeins into about 15 components. Each procedure gave characteristic patterns of zein bands for a number of maize inbreds. IEF and SDS-PAGE were used serially so that each band separated by IEF could be assayed as an individual SDS-PAGE sample. Some IEF bands revealed only a single band after SDS-PAGE, while others revealed two or more bands. A nomenclature system is presented which integrates the two separation systems with information about chromosome locations of zein genes, maize mutations which affect zein synthesis, and inbred sources for different zeins. SDS-PAGE of zein gives apparent molecular masses which vary widely according to the standards used and the properties of the gels, therefore an artificial nomenclature for identifying zein bands after SDS-PAGE is presented. The new nomenclature provides a flexible system which is useful and can be conveniently used in different laboratories.

The usefulness and limitations of estimating the number of genes in a barley breeding programme

SUMMARYRandom inbred lines produced by doubled haploidy and single seed descent have been used to estimate the number of genes or more correctly effective factors (k) controlling quantitative characters in barley. Estimates of k obtained by various biometrical methods are generally an underestimate since the effective factor may be considered a unit only in a temporary sense. In the past, estimates of k have been used to predict the range of inbreds extractable from a cross. Alternative and efficient methods are now available to predict the number of inbreds expected to exceed any given standard. Under these circumstances the need to estimate the number of genes is questionable.