Suppression of genetic recombination in the pseudoautosomal region and at subtelomeres in mice with a hypomorphic Spo11 allele.

BACKGROUND: Homologous recombination is the key process that generates genetic diversity and drives evolution. SPO11 protein triggers recombination by introducing DNA double stranded breaks at discreet areas of the genome called recombination hotspots. The hotspot locations are largely determined by the DNA binding specificity of the PRDM9 protein in human, mice and most other mammals. In budding yeast Saccharomyces cerevisae, which lacks a Prdm9 gene, meiotic breaks are formed opportunistically in the regions of accessible chromatin, primarily at gene promoters. The genome-wide distribution of hotspots in this organism can be altered by tethering Spo11 protein to Gal4 recognition sequences in the strain expressing Spo11 attached to the DNA binding domain of the Gal4 transcription factor. To establish whether similar re-targeting of meiotic breaks can be achieved in PRDM9-containing organisms we have generated a Gal4BD-Spo11 mouse that expresses SPO11 protein joined to the DNA binding domain of yeast Gal4. RESULTS: We have mapped the genome-wide distribution of the recombination initiation sites in the Gal4BD-Spo11 mice. More than two hundred of the hotspots in these mice were novel and were likely defined by Gal4BD, as the Gal4 consensus motif was clustered around the centers in these hotspots. Surprisingly, meiotic DNA breaks in the Gal4BD-Spo11 mice were significantly depleted near the ends of chromosomes. The effect is particularly striking at the pseudoautosomal region of the X and Y chromosomes - normally the hottest region in the genome. CONCLUSIONS: Our data suggest that specific, yet-unidentified factors influence the initiation of meiotic recombination at subtelomeric chromosomal regions.

A Study of the Interaction of Bovine Hemoglobin with Synthetic Dyes Using Spectroscopic Techniques and Molecular Docking.

Synthetic dyes are a very efficient class of dyes that are ingested or come into contact with the skin from numerous sources (cosmetics, textiles, leather, paper, and drugs). An important component of their safety profile is the interactions that they form after they enter the body. Hemoglobin is a functionally important protein that can form multiple interactions with soluble compounds present in the blood, and hence forms an important aspect of the toxicological or safety profile of the dyes. Here we study the interaction between bovine hemoglobin and organic dyes using UV-Vis absorbance and fluorescence spectroscopy. Molecular modeling was used to visualize the binding site and partners of the dye molecules, within the hemoglobin molecule. We find that all four dyes studied form sufficiently strong interactions with hemoglobin to allow for the formation of potentially toxic interactions. Molecular modeling showed that all four dyes bind within the central cavity of the hemoglobin molecule. However, binding partners could not be identified as multiple binding conformations with very similar energies were possible for each dye.

Rapid screening for entry inhibitors of highly pathogenic viruses under low-level biocontainment.

Emerging viruses including Nipah, Hendra, Lujo, and Junin viruses have enormous potential to spread rapidly. Nipah virus, after emerging as a zoonosis, has also evolved the capacity for human-to-human transmission. Most of the diseases caused by these pathogens are untreatable and require high biocontainment conditions. Universal methods for rapidly identifying and screening candidate antivirals are urgently needed. We have developed a modular antiviral platform strategy that relies on simple bioinformatic and genetic information about each pathogen. Central to this platform is the use of envelope glycoprotein cDNAs to establish multi-cycle replication systems under BSL2 conditions for viral pathogens that normally require BSL3 and BSL4 facilities. We generated monoclonal antibodies against Nipah G by cDNA immunization in rats, and we showed that these antibodies neutralize both Nipah and Hendra live viruses. We then used these effective Henipavirus inhibitors to validate our screening strategy. Our proposed strategy should contribute to the response capability for emerging infectious diseases, providing a way to initiate antiviral development immediately upon identifying novel viruses.