New Findings r What is the central question of this study?We asked whether the combination of astaxanthin supplementation and intermittent loading would attenuate both the muscle atrophy and the capillary regression associated with chronic unloading. r What is the main finding and its importance?Intermittent loading alone attenuated atrophy of the soleus, while astaxanthin treatment alone maintained the capillary network in the soleus. The combination of these two interventions ameliorated both the muscle atrophy and the capillary regression induced by chronic unloading.A chronic decrease in neuromuscular activity (activation and/or loading) results in muscle atrophy and capillary regression that are due, in part, to the overproduction of reactive oxygen species. We have reported that antioxidant treatment with astaxanthin attenuates the overexpression of reactive oxygen species in atrophied muscles that, in turn, ameliorates capillary regression in hindlimb-unloaded rats. Astaxanthin supplementation, however, had little effect on muscle mass and fibre cross-sectional area. In contrast, intermittent loading of the hindlimbs of hindlimb-unloaded rats ameliorates muscle atrophy. Therefore, we hypothesized that the combination of astaxanthin supplementation and intermittent loading would attenuate both muscle atrophy and capillary regression during hindlimb unloading. As expected, 2 weeks of hindlimb unloading resulted in atrophy, a decrease in capillary volume and a shift towards smaller-diameter capillaries in the soleus muscle. Intermittent loading alone (1 h of cage ambulation per day) attenuated atrophy of the soleus, while astaxanthin treatment alone maintained the capillary network to near control levels. The combination of intermittent loading and astaxanthin treatment, however, ameliorated atrophy of the soleus and maintained the capillary volume and luminal diameters and the superoxide dismutase-1 protein levels near control values. These results indicate that intermittent loading combined with astaxanthin

These results suggest that astaxanthin may be an effective treatment to counter the detrimental effects of a chronic decrease in skeletal muscle use on the capillary network and associated angiogenic pathways.

2-Aminophenol 1,6-dioxygenase was purified from the cell extracts of Pseudomonas sp. AP-3 grown on 2-aminophenol. The product from 2-aminophenol by catalysis of the purified enzyme was identified as 2-aminomuconic 6-semialdehyde by gas chromatographic and mass spectrometric analyses. The molecular mass of the native enzyme was 140 kDa based on gel filtration. It was dissociated into molecular mass subunits of 32 (␣-subunit) and 40 kDa (␤-subunit) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that the dioxygenase was a heterotetramer of ␣ 2 ␤ 2 . The genes coding for the ␣-and ␤-subunits of the enzyme were cloned and sequenced. Open reading frames of the genes (amnA and amnB) were 816 and 918 base pairs in length, respectively. The amino acid sequences predicted from the open reading frames of amnA and amnB corresponded to the NH 2 -terminal amino acid sequences of the ␣-subunit (AmnA) and ␤-subunit (AmnB), respectively. The deduced amino acid sequences of AmnB showed identities to some extent with HpaD (25.4%) and HpcB (24.4%) that are homoprotocatechuate 2,3-dioxygenases from Escherichia coli W and C, respectively, belonging to class III in the extradiol dioxygenases. On the other hand, AmnA had identity (23.3%) with only AmnB among the enzymes examined.Dioxygenases catalyzing the fission of benzene rings are key enzymes in the metabolic pathways of aromatic compounds by microorganisms. Most of these kinds of previously reported dioxygenases attack monocyclic aromatic compounds with two adjacent hydroxyl groups such as catechol and protocatechuic acid and open the benzene rings through the intradiol or extradiol fission reaction (1, 2). However, some bacteria have been reported to synthesize dioxygenases that cleave the benzene rings of hydroquinone (3-5) and gentisic acid (6, 7).In our investigations on the microbial metabolism of anilines, we isolated several microorganisms capable of growing on 2-aminophenol as the sole carbon, nitrogen, and energy source. When one isolate, Pseudomonas sp. AP-3, grows with this substrate, it synthesizes an enzyme acting on 2-aminophenol. This enzyme was partially purified with a 103-fold increase in the specific activity from its cell extracts. We proposed that the enzyme is a dioxygenase catalyzing the ring fission of 2-aminophenol with the consumption of 1 mol of O 2 per mol of substrate (8).Our aim was to advance the purification of 2-aminophenol 1,6-dioxygenase from Pseudomonas sp. AP-3 and elucidate the molecular and catalytic properties of the purified enzyme. Because the product from 2-aminophenol by catalysis of the enzyme is rapidly and nonenzymatically converted into picolinate (8, 9), the real product has remained unverified. Furthermore, we attempted the cloning and sequencing of the gene of the dioxygenase, which would determine the category of this enzyme in the dioxygenase groups.Recently, Lendenmann and Spain (10) reported the purification and characterization of the 2-aminophenol 1,6-dioxygenase from nitrobenzene-degrading Pseudomo...

Pseudomonas sp. strain 7-6, isolated from active sludge obtained from a wastewater facility, utilized a quaternary ammonium surfactant, n-dodecyltrimethylammonium chloride (DTAC), as its sole carbon, nitrogen, and energy source. When initially grown in the presence of 10 mM DTAC medium, the isolate was unable to degrade DTAC. The strain was cultivated in gradually increasing concentrations of the surfactant until continuous exposure led to high tolerance and biodegradation of the compound. Based on the identification of five metabolites by gas chromatography-mass spectrometry analysis, two possible pathways for DTAC metabolism were proposed. In pathway 1, DTAC is converted to lauric acid via n-dodecanal with the release of trimethylamine; in pathway 2, DTAC is converted to lauric acid via n-dodecyldimethylamine and then n-dodecanal with the release of dimethylamine. Among the identified metabolites, the strain precultivated on DTAC medium could utilize n-dodecanal and lauric acid as sole carbon sources and trimethylamine and dimethylamine as sole nitrogen sources, but it could not efficiently utilize n-dodecyldimethylamine. These results indicated pathway 1 is the main pathway for the degradation of DTAC.Quaternary ammonium compounds (QACs) containing a long-chain alkyl group or a benzyl group are cationic surfactants that are widely used in several applications, including as antistatic agents, emulsifiers-dispersants, dye auxiliaries, surface treatment agents, osmotic agents, and hair rinses (8). QACs are also contained in synthetic detergents to reduce static electricity in clothing and improve fabric suppleness. In addition, the bactericidal and fungicidal properties of these compounds, as well as their ability to damage cell membranes and to denature cell proteins, have favored their widespread use in domestic cleaning products (1, 6, 7). Since most of the above-mentioned products are released into the environment through routine disposal wastewater, the accumulation and aquatic toxicity of quaternary-ammonium-based surfactants have been the focus of several studies (4,20).Several researchers have reported adaptation to QACs by aquatic organisms through their repeated exposure to these compounds (19) and the biodegradation of QACs by pure cultures of bacteria (18). McBain et al. showed that repeated exposure of pure cultures, especially Ralstonia sp., altered their susceptibility to QACs (11). In addition, a mixture of Pseudomonas sp. and Xanthomonas sp. isolated from soil and sewage grew well on medium containing decyltrimethylammonium salt as the sole carbon source. Xanthomonas sp. oxidized the terminal carbon of the alkyl chain of QAC (2). Pseudomonas sp. strain B1, isolated from activated sludge, grew well on hexadecyltrimethylammonium chloride (the C16 alkyl QAC in this report), using the compound as a carbon and energy source (17). However, strain B1 could not utilize the intermediate, trimethylamine, as a nitrogen source. Although these findings indicate the metabolic fates of QACs in an aquatic envir...