Quantitative genetic analysis station for the genetic analysis of complex traits

The Quantitative Genetic Analysis Station (QGAStation) is a software package that has been developed to perform statistical analysis for complex traits. It consists of five domains for handling data from diallel crosses, regional trials, core germplasm collections, QTL mapping, and microarray experiments. The first domain contains genetic models for diallel cross analysis, in which genetic variance components and genetic-by-environment interactions can be estimated, and genetic effects can be predicted. The second domain evaluates the performance of varieties in regional trials by implementing a general statistical method that outperforms ANOVA in tackling unbalanced data that arises frequently in trials across multiple locations and over a number of years. The third domain, using predicted genotypic values as proxy, constructs core germplasm collections covering sufficient genetic diversity with lower redundancy. The fourth domain manages genotypic and phenotypic data for QTL mapping. Linkage maps can be constructed and genetic distances can be estimated; the statistical methods that have been implemented apply to both chiasmatic and achiasmatic organisms. Another part of this domain can filter systematic noises in phenotypic data. The fifth domain focuses on the cDNA expression data that is generated by microarray experiments. A two-step strategy has been implemented to detect differentially expressed genes and to estimate their effects. Except in the fourth domain, the major statistical methods that have been used are mixed linear model approaches that have been implemented in the C language. Computational efficiency is further boosted for computers that are equipped with graphics processing units (GPUs). A user friendly graphic interface is provided for Microsoft Windows and Apple Mac operating systems. QGAStation is available at http: //ibi.zju.edu.cn/software/qga/

White Cells Facilitate Opposite- and Same-Sex Mating of Opaque Cells in Candida albicans

Modes of sexual reproduction in eukaryotic organisms are extremely diverse. The human fungal pathogen Candida albicans undergoes a phenotypic switch from the white to the opaque phase in order to become mating-competent. In this study, we report that functionally- and morphologically-differentiated white and opaque cells show a coordinated behavior during mating. Although white cells are mating-incompetent, they can produce sexual pheromones when treated with pheromones of the opposite mating type or by physically interacting with opaque cells of the opposite mating type. In a co-culture system, pheromones released by white cells induce opaque cells to form mating projections, and facilitate both opposite- and same-sex mating of opaque cells. Deletion of genes encoding the pheromone precursor proteins and inactivation of the pheromone response signaling pathway (Ste2-MAPK-Cph1) impair the promoting role of white cells (MTLa) in the sexual mating of opaque cells. White and opaque cells communicate via a paracrine pheromone signaling system, creating an environment conducive to sexual mating. This coordination between the two different cell types may be a trade-off strategy between sexual and asexual lifestyles in C. albicans