Use of positive reinforcement conditioning to monitor pregnancy in an unanesthetized snow leopard (Uncia uncia) via transabdominal ultrasound

Closely monitoring snow leopard (Uncia uncia) fetal developments via transabdominal ultrasound, with minimal stress to the animal, was the goal of this project. The staff at Potter Park Zoo has used the principles of habituation, desensitization, and positive reinforcement to train a female snow leopard (U. uncia). Ultrasound examinations were preformed on an unanesthetized feline at 63 and 84 days. The animal remained calm and compliant throughout both procedures. Fetuses were observed and measured on both occasions. The absence of anesthesia eliminated components of psychologic and physiologic stress associated with sedation. This was the first recorded instance of transabdominal ultrasound being carried out on an unanesthetized snow leopard. It documents the feasibility of detecting pregnancy and monitoring fetal development via ultrasound. Zoo Biol 27:78–85, 2008. © 2007 Wiley‐Liss, Inc.     

Regulation of fatty acid synthesis and Δ9-desaturation in senescence of human fibroblasts

AimsNormal human cells in culture progressively lose their capacity for replication, ending in an irreversible arrested state known as replicative senescence. Senescence has been functionally associated to the process of organismal ageing and is also considered a major tumor-suppressing mechanism. Although a great deal of knowledge has uncovered many of the molecular aspects of senescence, little is known about the regulation of lipid synthesis, particularly the biosynthesis and Δ9-desaturation of fatty acids, during the senescence process.Main methodsBy using immunoblotting and metabolic radiolabeling, we determined the senescence-associated changes in major lipogenic pathways.Key findingsThe levels of fatty acid synthase and stearoyl-CoA desaturase-1 and, consequently, the formation of monounsaturated fatty acids, were notably decreased in senescent cells when compared to proliferating (young) fibroblasts. Moreover, we detected a reduction in the de novo synthesis of phospholipids with a concomitant increase in the formation of cholesterol in senescent cells compared to young fibroblasts. Finally, it was found that exogenous fatty acids were preferentially incorporated into the triacylglycerol pool of senescent cells.SignificanceThis set of observations is the first demonstration of a profound modification in lipid metabolism, particularly fatty acid biosynthesis and desaturation, caused by the senescence process and contributes to the increasing body of evidence linking de novo lipogenesis with cellular proliferation.     

GeneComps and ChemComps: a new CTD metric to identify genes and chemicals with shared toxicogenomic profiles

The Comparative Toxicogenomics Database is a public resource that promotes understanding about the effects of environmental chemicals on human health. Currently, CTD describes over 184,000 molecular interactions for more than 5,100 chemicals and 16,300 genes/proteins. We have leveraged this dataset of chemical-gene relationships to compute similarity indices following the statistical method of the Jaccard index. These scores are used to produce lists of comparable genes (“GeneComps”) or chemicals (“ChemComps”) based on shared toxicogenomic profiles. GeneComps and ChemComps are now provided for every curated gene and chemical in CTD. ChemComps are particularly significant because they provide a way to group chemicals based upon their biological effects, instead of their physical or structural properties. These metrics provide a novel way to view and classify genes and chemicals and will help advance testable hypotheses about environmental chemical-genedisease networks.

Availability

CTD is freely available at http://ctd.mdibl.org/     

Structural Effects and Translocation of Doxorubicin in a DPPC/Chol Bilayer: The Role of Cholesterol

We use molecular dynamics simulations to characterize the influence of cholesterol (Chol) on the interaction between the anticancer drug doxorubicin (DOX) and a dipalmitoyl phosphatidylcholine/Chol lipid bilayer. We calculate the potential of mean force, which gives us an estimate of the free energy barrier for DOX translocation across the membrane. We find free energy barriers of 23.1 ± 3.1 k_BT, 36.8 ± 5.1 k_BT, and 54.5 ± 4.7 k_BT for systems composed of 0%, 15%, and 30% Chol, respectively. Our predictions agree with Arrhenius activation energies from experiments using phospholipid membranes, including 20 k_BT for 0% Chol and 37.2 k_BT for 20% Chol. The location of the free energy barrier for translocation across the bilayer is dependent on composition. As Chol concentration increases, this barrier changes from the release of DOX into the water to flip-flop over the membrane center. The drug greatly affects local membrane structure by attracting dipalmitoyl phosphatidylcholine headgroups, curving the membrane, and allowing water penetration. Despite its hydrophobicity, DOX facilitates water transport via its polar groups.     

Solanesyl Diphosphate Synthase,an Enzyme of the Ubiquinone Synthetic Pathway,Is Required throughout the Life Cycle of Trypanosoma brucei

Ubiquinone 9 (UQ9), the expected product of the long-chain solanesyl diphosphate synthase of Trypanosoma brucei (TbSPPS), has a central role in reoxidation of reducing equivalents in the mitochondrion of T. brucei. The ablation of TbSPPS gene expression by RNA interference increased the generation of reactive oxygen species and reduced cell growth and oxygen consumption. The addition of glycerol to the culture medium exacerbated the phenotype by blocking its endogenous generation and excretion. The participation of TbSPPS in UQ synthesis was further confirmed by growth rescue using UQ with 10 isoprenyl subunits (UQ10). Furthermore, the survival of infected mice was prolonged upon the downregulation of TbSPPS and/or the addition of glycerol to drinking water. TbSPPS is inhibited by 1-[(n-oct-1-ylamino)ethyl] 1,1-bisphosphonic acid, and treatment with this compound was lethal for the cells. The findings that both UQ9 and ATP pools were severely depleted by the drug and that exogenous UQ10 was able to fully rescue growth of the inhibited parasites strongly suggest that TbSPPS and UQ synthesis are the main targets of the drug. These two strategies highlight the importance of TbSPPS for T. brucei, justifying further efforts to validate it as a new drug target.     

Analysis of the excision repair of nondimer DNA damage induced by solar ultraviolet radiation in ICR 2A frog cells

The excision repair of solar uv-induced nondimer DNA damage was examined in ICR 2A frog cells through the use of the bromodeoxyuridine (BrdUrd) photolysis assay. A relatively pure population of nondimer DNA photoproducts was induced by irradiation of ICR 2A cells with the Mylar-filtered solar ultraviolet (uv) wavelengths produced by a fluorescent sunlamp followed by exposure to photoreactivating light (PRL) which removes most of the small yield of pyrimidine dimers induced by this treatment. Cultures of cells were also exposed to 254 nm uv, which induces primarily dimers, and 60Co gamma rays. Through use of a modification of the BrdUrd photolysis assay possessing enhanced sensitivity, it was found that the solar uv-induced nondimer DNA damage was repaired by a short patch repair mechanism in which less than approximately 20 nucleotides are inserted into a repaired region. Similar results were also obtained for gamma-irradiated cells. In contrast, excision repair of 254-nm-induced dimers was accomplished by a long-patch process in which an average of about 180 nucleotides are inserted into the repaired sites.     

Immunocytochemical demonstration of retinal S-antigen in the pineal organ of four mammalian species

By means of immunocytochemistry retinal S-antigen is selectively demonstrated in retinal photoreceptor cells of the rat and in pinealocytes of the hedgehog, rat, gerbil and cat. Brain areas surrounding the pineal organ are immunonegative. The immunoreactive material is evenly distributed in the perikarya of the cells. Occasionally, inner segments of retinal photoreceptors and processes of pinealocytes are also stained. The outer segments of retinal photoreceptors display a strong immunoreaction. In both pinealocytes and retinal photoreceptors the intensity of the immunoreaction varied considerably among individual cells. The immunocytochemical demonstration of retinal S-antigen in mammalian pinealocytes indicates that these cells still bear characteristics of photoreceptors. This finding is in accord with the concept that mammalian pinealocytes are derived from pineal photoreceptor cells of poikilothermic vertebrates.