Involvement of mammalian Mus81 in genome integrity and tumor suppression

Mus81-Eme1 endonuclease has been implicated in the rescue of stalled replication forks and the resolution of meiotic recombination intermediates in yeast. We used gene targeting to study the physiological requirements of Mus81 in mammals. Mus81-/- mice are viable and fertile, which indicates that mammalian Mus81 is not essential for recombination processes associated with meiosis. Mus81-deficient mice and cells were hypersensitive to the DNA cross-linking agent mitomycin C but not to gamma-irradiation. Remarkably, both homozygous Mus81-/- and heterozygous Mus81+/- mice exhibited a similar susceptibility to spontaneous chromosomal damage and a profound and equivalent predisposition to lymphomas and other cancers. These studies demonstrate a critical role for the proper biallelic expression of the mammalian Mus81 in the maintenance of genomic integrity and tumor suppression.     

Lhx2 selector activity specifies cortical identity and suppresses hippocampal organizer fate

The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer.     

Diviner Lunar Radiometer observations of the LCROSS impact

The Lunar Reconnaissance Orbiter (LRO) Diviner instrument detected a thermal emission signature 90 seconds after the Lunar Crater Observation and Sensing Satellite (LCROSS) Centaur impact and on two subsequent orbits. The impact heated a region of 30 to 200 square meters to at least 950 kelvin, providing a sustained heat source for the sublimation of up to ~300 kilograms of water ice during the 4 minutes of LCROSS post-impact observations. Diviner visible observations constrain the mass of the sunlit ejecta column to be ~10(-6) to 10(-5) kilograms per square meter, which is consistent with LCROSS estimates used to derive the relative abundance of the ice within the regolith.     

Diviner Lunar Radiometer observations of cold traps in the Moon's south polar region

Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond the boundaries of persistent shadow. The Lunar Crater Observation and Sensing Satellite (LCROSS) struck one of the coldest of these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas of the lunar polar regions are currently cold enough to cold-trap water ice as well as a range of both more volatile and less volatile species. The diverse mixture of water and high-volatility compounds detected in the LCROSS ejecta plume is strong evidence for the impact delivery and cold-trapping of volatiles derived from primitive outer solar system bodies.     

Immunogenic and antigenic properties of recombinant soluble glycoprotein of rabies virus

Rabies virus glycoprotein is a type I transmembrane protein exposed on the surface on the mature virus particle that induces virus neutralizing antibodies. In the present study, 60 amino acid C-terminal hydrophobic anchor (transmembrane) and cytoplasmic domains of glycoprotein were deleted from full-length glycoprotein and fused with polyhistidine tag. The N-terminal viral signal peptide was also replaced with CD33 signal peptide for efficient secretion in mammalian cells. Following transfection of Madin Darby bovine kidney (MDBK) cells with plasmid encoding this soluble form of glycoprotein, polyclonal populations of stably transfected resistant cells were obtained after G418 selection. The protein was expressed as a glycosylated protein and secreted outside the cells utilizing N-terminal CD33 signal peptide. The secreted soluble glycoprotein was purified from cell culture supernatant by Ni--agarose affinity chromatography utilizing C-terminal polyhistidine tag. Like full-length glycoprotein, the expressed recombinant soluble glycoprotein was found to be immunogenic when injected in rabbits. In this study, we have assessed the potential of recombinant soluble glycoprotein as diagnostic antigen in ELISA and found that this recombinant protein can be used as diagnostic antigen in ELISA for detecting anti-glycoprotein antibodies in immunized host.     

Verification of compliance with organic meat production standards by detection of permitted and nonpermitted uses of veterinary medicines (tetracycline antibiotics)

In the production of "organic" meat, one of the controlled processes is the use of veterinary drugs. Strict standards are in place as to when and how such drugs may be used. Therefore, the aim of this project was to determine whether it was possible to distinguish between a single therapeutic dose of a tetracycline (permitted under the standards) and both multiple therapeutic dosing and prophylactic dosing (not permitted). This comprised an evaluation of (i) pigs that were treated with oxytetracycline and (ii) chickens dosed with two different tetracycline antibiotics (oxytetracycline and chlortetracycline). The methodology described, using bone sectioning and examination under ultraviolet illumination (either direct observation or fluorescent microscopy), allows samples from animals that have been treated with different dosing regimes (a single therapeutic dose, two successive therapeutic doses, and long-term, low-level "prophylactic" dosing) to be assessed for compliance with organic farming regulations. Validation of the methodology by blind checks of unknown samples by a second operator has been successfully performed, and validation results are presented. The developed methodology has been shown to be applicable to a variety of species and a selection of tetracycline drugs.     

Disease suppressive effects of resistance-inducing agents against red rot of sugarcane

Red rot caused by Colletotrichum falcatum is one of the most devastating fungal diseases of sugarcane in many tropical countries. In this study, the efficacy of various resistance-inducing agents was evaluated against red rot at two growth phases of sugarcane, i.e., the germination and grand growth phases, for four consecutive cropping seasons (2011–12 to 2014–15) under field conditions. Inducer candidates of both synthetic origin (benzothiadiazole [BTH], salicylic acid [SA], potassium silicate [PSi]) and biotic origin (Colletotrichum falcatum [Cf] elicitor and Reynoutria sachalinensis extract) were evaluated for their efficacy on a red rot susceptible sugarcane cultivar CoC 671. Inducer concentrations that showed significant reduction of red rot lesion length in leaf bioassays without exhibiting direct antifungal activity were used in the field trials. Overall, results of the four field trials indicated that application of BTH (125 μM) and Cf elicitor (60 μg glucose equivalent/ml) were most efficient in reducing disease incidence during the germination and establishment phases against soil-borne inoculum and suppressed disease severity in pathogen challenged cane stalks during the grand growth phase. In addition, other treatments also had significant effects on germination and stalk disease severity. Quantification of C. falcatum biomass in resistance inducer-treated canes by quantitative PCR (qPCR) substantiated the disease suppressive effect of BTH and Cf elicitor. Whereas all resistance inducers significantly increased the cane weight, only BTH and PSi significantly increased the juice quantity. Other juice quality parameters were generally not affected by the inducers.