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Monoamine oxidase (MAO) is a mitochondrial membrane-bound enzyme that catalyzes the oxidative deamination of monoamines in a wide array of organisms. While the enzyme monoamine oxidase has been studied extensively in its role in moderating behavior in mammals, there is a paucity of research investigating this role in invertebrates, where the latter utilizes this enzyme in a major pathway to degrade monoamines. There is especially a dismal lack of information on how MAO influences activity in invertebrates, particularly in account of the circadian cycle. Previous studies revealed MAO degrades serotonin and norepinephrine in arachnids, but did not investigate other critically important compounds like octopamine. Larinioides cornutus is a species of orb-weaving spider that exhibits diel fluctuations in behavior, specifically levels of aggression. The monoamines octopamine and serotonin have been shown to influence aggressive behaviors in L. cornutus, thus this species was used to investigate if MAO is a potential site of regulation throughout the day. Not only did gene expression of MAO orthologs and MAO activity fluctuate at different times of day, but the enzymatic activity was substrate-specific producing a higher level of degradation of octopamine as compared to serotonin in vitro. This study further supports evidence that MAO has an active role in monoamine inactivation in invertebrates and provides a first look at how MAO ultimately may be regulating behavior in an invertebrate.

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We determined genetic variance and gene flow across multiple scales (reaches, headwater segments, and catchments) to examine the dispersal ability of the flatworm Polycelis coronata along the Wasatch Mountains of Utah. Multiple models predict patterns of genetic differentiation in stream invertebrates based on dispersal traits and the spatial connectivity of the habitat. The stream hierarchy model predicts genetic differentiation to be low and gene flow to be high between reaches nested in segments, moderate among segments within catchments, and differentiation to be highest and gene flow lowest among catchments, whereas the headwater model predicts the greatest differentiation between headwater segments. Our objective was to determine which model best described genetic patterns observed in P. coronata. Using a nested hierarchical sampling design ensured that if limitations to dispersal had an effect on genetic differentiation, we would be able to identify at what scale these processes operate. We hypothesized genetic variation would be small within headwater segments and reach maximum levels between headwater segments with no increase in differentiation with increasing distance between headwater patches or between drainages. We do not expect high dispersal along the stream network or across the terrestrial environment (actively or passively).We generated DNA sequence data (mitochondrial COI) from 50 sites nested within 24 segments, which were nested in four adjacent catchments. We identified 134 haplotypes from 506 individuals using a 763 bp fragment of mtDNA. Genetic patterns did not conform to the SH model. Evidence from one drainage (Provo River) was consistent with the headwater model. However, high differentiation within sites suggested that the genetic patterns we uncovered may be representative of high ancestral polymorphism among pre-fragmented populations that were historically widespread. Large effective population sizes and no evidence of bottleneck events suggest incomplete lineage cannot be discounted as an explanation of high differentiation at the smallest scales.

Cerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water-based-wet-chemical method to synthesize biocompatible,stable and highly monodisperse polymer coated cerium oxide nanoparticles. Polymer coated cerium oxide nanoparticles possess all the characteristics of the uncoated cerium oxide nanoparticles. These nanoparticles were found to be effective as pH-dependent antioxidant giving cytoprotection to normal cell lines against hydrogen peroxide and nitric oxide radical but not to cancer cells. Moreover, cerium oxide nanoparticle also exhibits unique oxidase-like activity at acidic pH oxidizing a series of organic compound without the need of hydrogen peroxide. Based on these results, we have designed an immunoassay in which folate-conjugated cerium oxide nanoparticles provide dual functionality by binding to folate expressing cancer cells and facilitating detection by catalytic oxidation of sensitive colorimetric substrates (dyes). Finally, we have shown that the polymer coated cerium oxide nanoparticles shows distinct toxicity depending upon their subcellular localization based on uptake studies using DiI loaded cerium oxide nanoparticles. In these results, we have found that cerium oxide nanoparticles entrapped into lysosomes are more toxic as opposed to when they are localized in the cytoplasm.Overall we propose that the polymer coated cerium oxide nanoparticles displays selective antioxidant property, oxidase-like activity, and cytotoxicity to biological systems depending upon its pH environment.

The interaction of the 2,3-diazanaphthalene, phthalazine and its 1-substituted derivatives with the molybdenum hydroxylases, aldehyde oxidase and xanthine oxidase, has been investigated both in vivo and /Ok in vitro. Metabolic studies, carried out by treating rabbits with both cold and 14C-labelled phthalazine, have shown that this compound is extensively metabolised in vivo, the major metabolite being a glucuronide conjugate. Very little unchanged phthalazine or its molybdenum hydroxylase mediated oxidation product 1-hydroxyphthalazine were excreted in the urine. Pretreatment of rabbits with phthalazine or 1-hydroxyphthalazine had no effect upon the activity of the microsomal monooxygenases but caused a significant increase in the specific activities of both aldehyde oxidase and xanthine oxidase. Determination of the molybdenum content of purified aldehyde oxidase fractions using electrothermal atomic absorption spectroscopy has confirmed that an increase in the molybdenum content of the enzyme fraction accompanies the increase in activity. A qualitative assessment of purified aldehyde oxidase fractions using iso-electric focusing has indicated that this enzyme may be composed of 2 or 3 active variants and following pretreatment with either phthalazine or 1-hydroxyphthalazine a further band of enzyme activity is apparent on the electropherogram. The Km value for phthalazine is significantly reduced with enzyme prepared from phthalazine treated rabbits, indicating that a form of the enzyme with a high affinity for phthalazine may have been induced. 1-Hydrazinophthalazine (Hydralazine) and two other hydrazine substituted N-heterocycles, endralazine and 1-hydrazinoisoquinoline have been shown to exert a potent progressive inhibition of aldehyde oxidase in vitro, effective only in the presence of substrate, but are inactive towards xanthine oxidase. In addition, administration of hydralazine to rabbits results in a significant reduction in liver aldehyde oxidase activity. Investigations into the interaction of some of the metabolites of hydralazine with aldehyde oxidase in vitro suggest that hydralazine is also the inhibiting species in vivo. / The Ransom Fellowship awarded by The Pharmaceutical Society of Great Britain,

Aldehyde oxidase catalysed oxidation of various quinolinium and related cations has been studied in vitro. Oxidation products were identified by comparison of their spectral and chromatographic characteristics with those of authentic compounds. The N-heterocyclic cations and quinolones used required synthesis. Incubation of N-methylquinolinium, N-methyl-7,8-benzoquinolinium and N-phenylquinolinium yielded the corresponding 2- and 4-quinolones simultaneously. The ratio of 2- to 4-quinolone formation was found to be species dependent; the proportion of 4-quinolone was greater with guinea pig enzyme than with rabbit enzyme. Incubation of N-methyl-4-methylquinolinium, N-methyl-4-phenylquinolinium and N-methylphenanthridinium produced the expected 2-quinolones. Cations substituted adjacent to the ring nitrogen, i. e. N-methyl-2- methylquinolinium, N-methyl-2-phenylquinolinium and N-phenyl-2-phenylquinolinium, were oxidised to the corresponding 4-quinolones. Kinetic constants were determined spectrophotometrically. The Km values obtained with rabbit enzyme ranged from 1.6 x 10-3 M for N-methylquinolinium to <10-5 M for N-phenyl-2-phenylquinolinium. Quaternary compounds were found to be better substrates than their non-quaternary counterparts, except for N-methylisoquinolinium and N-methylphenanthridinium. In general, guinea pig aldehyde oxidase was shown to have a greater affinity for N-heterocyclic cations than rabbit enzyme. The substrate binding site has been discussed in the light of the results outlined below. Oxidation of N-methyl-4-phenylquinolinium (to the 2-quinolone) was competitively inhibited by N-methyl-2-phenylquinolinium (which yields the 4-quinolone), indicating that both these cations interact at the same active site. The ratio of 2- to 4-quinolone production from N-methylquinolinium was constant under various conditions, including purification of the enzyme but changed at high pH or in the presence of N-methylphenanthridinium. Inhibition studies indicated that both quaternary and non-quaternary compounds act at the same site on the enzyme. Km and Vmax values for phthalazine, N-methyl-2-phenylquinolinium and N-methylquinolinium were determined over the pH range 5.4 to 10.2. In each case, results indicated that the enzyme has an ionisable group at the active site with a pK ca. 8. Aldehyde oxidase was shown to catalyse the dehydrogenation of the pseudobases 3,4-dihydro-4-hydroxy-3-methyl-2-quinazolinone and 3,4-dihydro- 4-hydroxy-3-methylquinazoline.

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