Developmental changes of carbonic anhydrase in the retina of the mouse: a histochemical study

Synopsis In the optic cup of early mouse embryos, carbonic anhydrase activity is seen only in the pigment epithelial cells. During the late prenatal period the enzyme appears in the Müller cells, first in the perikarya. During the postnatal development the enzyme activity appears in the radial processes of the Müller cells starting at the vitreal border along with the separation of the outer retinal layers. This is followed by increased activity in the plexiform layers, presumably in the lateral processes. Carbonic anhydrase localization in pigment epithelial and Müller cells attains the adult pattern at about 16 days corresponding with the initiation of retinal function.     

Evaluation of surrogate markers of impending death in the galactosamine-sensitized murine model of bacterial endotoxemia.

BACKGROUND AND PURPOSE: When evaluating vaccines for efficacy against gram-negative endotoxemia, the challenge has historically required death of a large percentage of test subjects. We attempted to identify surrogate markers of impending death to allow for early euthanasia without interfering with experimental data collection. METHODS: Galactosamine-sensitized mice (n = 140) were inoculated intraperitoneally with various dosages of endotoxin, and development of clinical signs of disease--body temperature, body weight, hunched posture, ruffled coat, inability to ambulate, and loss of consciousness--was evaluated. RESULTS: Wide fluctuations in body temperature (+/- 4 degrees C) were observed in survivors and nonsurvivors. Posture, coat, and body weight were not accurate predictors of death. Only inability to ambulate, with a positive predictive value of 100% (11 of 11), accurately predicted death in the experimental mice of this study. CONCLUSION: Using this surrogate marker, loss of ability to ambulate, 11 of 13 mice that developed this sign could have been euthanized early, preventing anywhere from 2 to 22 h of potential distress prior to death.     

Interaction of UV and N-methyl-N'-nitro-N-nitrosoguanidine: cytotoxicity and mutagenicity in V79 cells

Killing and mutation by UV in the MNNG-exposed population of V79 cells, as well as by MNNG in the UV-irradiated population of these cells have been studied. It was observed that pretreatment with MNNG increased the killing and mutation by UV, whereas, pretreatment with UV had no effect upon killing and mutation by MNNG. The increase in sensitivity to UV due to pretreatment with MNNG was lost if UV exposure was delayed for 24 h after MNNG treatment.     

Placental superoxide dismutase 3 mediates benefits of maternal exercise on offspring health

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The possible involvement of CHI sequences in adaptive mutagenesis: Evidence from sequence analysis

Recently we proposed that sequences in the immediate neighbourhood of cytosine residues whose sequence context permits their methylation by DNA cytosine methyltransferase (Dcm) experience hypermutagenesis in cells exposed to nonlethal stresses. This hypothesis could explain the peculiar spectrum of the late-arising Lac⁺ mutants seen in theE. coli strain FC40. Here we present results of computer analysis which show that Dcm substrate sequences are overrepresented in theE. coli genome. Interestingly, certain noncanonical Dcm sequences are more overrepresented than the canonical one. The most overabundant of these, DCM-III (5’ GCTGG3’), forms the 5’ end of the recombinogenic octamer CHI (5’ GCTGGTGG3’). CHI is even more overrepresented than DCM-III. We propose that the overabundance of the DCM and CHI sequences is due to their ability to enhance adaptive fitness of the host by inducing hypermutagenesis in cells exposed to nonlethal, growth-blocking stresses. The CHI context seems to stimulate the adaptive activity of DCM-III by a mechanism which may not directly involve its recombinogenic activity.     

Bluejay 1.0: genome browsing and comparison with rich customization provision and dynamic resource linking

Background  

The Bluejay genome browser has been developed over several years to address the challenges posed by the ever increasing number of data types as well as the increasing volume of data in genome research. Beginning with a browser capable of rendering views of XML-based genomic information and providing scalable vector graphics output, we have now completed version 1.0 of the system with many additional features. Our development efforts were guided by our observation that biologists who use both gene expression profiling and comparative genomics gain functional insights above and beyond those provided by traditional per-gene analyses.     

Biosynthesis of lysine in Saccharomyces cervisiae: properties and spectrophotometric determination of homocitrate synthase activity.

A rapid assay is described for homocitrate synthase (EC 4.1.3.21) of the lysine biosynthetic pathway of Saccharomyces cerevisiae. The alpha-ketoglutarate-dependent cleavage of acetyl-coA was measured spectrophotometrically as decrease in absorbance at 600 nm in the presence of 2,6-dichlorophenol-indophenol and enzyme from the wild type strain X2180. This activity was also present in citrate synthaseless glutamate auxotroph glu3, and the activity was inhibited by 5 mM L-lysine. Radioactive homocitric acid was obtained from a reaction mixture containing [1-14C]acetyl-coA. Homocitrate synthase activity was dependent upon time, both substrates, and enzyme. The activity exhibited a pH and temperature optimum of 7.5-8.0 and 32 degrees C, respectively, and was inhibited by metal-chelating and sulfhydryl-binding agents.     

FTIR study of secondary structure changes in Epidermal Growth Factor by gold nanoparticle conjugation

Conformation of protein is vital to its function, but may get affected when processing to manufacture products. It is therefore important to understand structural changes during each step of production. In this study, we investigate secondary structure changes in the targeting protein Epidermal Growth Factor (EGF) during synthesis of theranostic bifunctional nanoparticle, devised for Photodynamic therapy of breast cancer. We acquired FTIR spectra of EGF; unconjugated, post treatment with α-lipoic acid, attached to gold nanoparticle, and bound to the bifunctional nanoprobe. We observed decreasing disordered structures and turns, and increasing loops, as the synthesis process progressed. There was an overall increase in β-sheets in final product compared to pure EGF, but this increase was not linear and fluctuated. Previous crystal structure studies on EGF-EGFR complex have shown loops and β-sheets to be important in the binding interaction. Since our study found increase in these structures in the final product, no adverse effect on binding function of EGF was expected. This was confirmed by functional assays. Such studies may help modify synthesis procedures, and thus secondary structures of proteins, enabling increased functionality and optimum results.