Functional genomics of the Drosophila melanogaster X chromosome and the role of DWnt5 during development

The collection of X chromosome insertions (PX) lethal lines, which was isolated from a screen for essential genes on the X chromosome, was characterized by means of cloning the insertion sites, mapping the sites within genomic DNA and determination of the associated reporter gene expresssion patterns. The established STS flanking the P element insertion sites were submitted to EMBL nucleotide databases and their in situ data together with the enhancer trap expression patterns have been deposited in the FlyView database. The characterized lines are now available to be used by the scientific community for a detailed analysis of the newly established lethal gene functions. One of the isolated genes on the X chromosome was the Drosophila gene Wnt5 (DWnt5). From two independent screens, one lethal and three homozygous viable alleles were recovered, allowing the identification of two distinct functions for DWnt5 in the fly. Observations on the developing nervous system of mutant embryos suggest that DWnt5 activity affects axon projection pattern. Elevated levels of DWNT5 activity in the midline cells of the central nervous system causes improper establishment and maintenance of the axonal pathways. Our analysis of the expression and mutant phenotype indicates that DWnt5 function in a process needed for proper organization of the nervous system. A second and novel function of DWnt5 is the control of the body size by regulation of the cell number rather than affecting the size of cells. Moreover, experimentally increased DWnt5 levels in a post-mitotic region of the eye imaginal disc causes abnormal cell cycle progression, resulting in additional ommatidia in the adult eye when compared to wild type. The increased cell number and the effects on the cell cycle after exposure to high DWNT5 levels is the result of a failure to downregulate cyclin B and therefore the unsuccessful establishment of a G1 arrest.

A pilot investigation of the relationship between climate variability and milk compounds under the bootstrap technique

This study analyzes the linear relationship between climate variables and milk components in Iran by applying bootstrapping to include and assess the uncertainty. The climate parameters, Temperature Humidity Index (THI) and Equivalent Temperature Index (ETI) are computed from the NASA-Modern Era Retrospective-Analysis for Research and Applications (NASA-MERRA) reanalysis (2002–2010). Milk data for fat, protein (measured on fresh matter bases), and milk yield are taken from 936,227 milk records for the same period, using cows fed by natural pasture from April to September. Confidence intervals for the regression model are calculated using the bootstrap technique. This method is applied to the original times series, generating statistically equivalent surrogate samples. As a result, despite the short time data and the related uncertainties, an interesting behavior of the relationships between milk compound and the climate parameters is visible. During spring only, a weak dependency of milk yield and climate variations is obvious, while fat and protein concentrations show reasonable correlations. In summer, milk yield shows a similar level of relationship with ETI, but not with temperature and THI. We suggest this methodology for studies in the field of the impacts of climate change and agriculture, also environment and food with short-term data.