Spatial distribution of total, ammonia-oxidizing, and denitrifying bacteria in biological wastewater treatment reactors for bioregenerative life support

Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project-Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation.     

Neurotoxic mechanisms triggered by Alzheimer's disease-linked mutant M146L presenilin 1: involvement of NO synthase via a novel pertussis toxin target

While it has been reported that familial Alzheimer's disease (FAD)-linked mutants of amyloid precursor protein (APP) and presenilin (PS)2 induce neuronal cytotoxicity in a manner sensitive to antioxidant and pertussis toxin (PTX), little of the mechanism for PS1-mediated neuronal cell death has been characterized. We previously found that multiple mechanisms, different in detail, underlie cytotoxicities by two FAD-linked mutants of APP, using neuronal cells with an ecdysone-controlled expression system. Here we report that this system revealed that (i) low expression of FAD-linked M146L-PS1 caused neuronal cell death, whereas that of wild-type (wt)PS1 did not; (ii) mutation-specific cytotoxicity by M146L-PS1 was sensitive to antioxidant glutathione-ethyl-ester and resistant to Ac-DEVD-CHO; (iii) cytotoxicity by higher expression of wtPS1 was resistant to both; and (iv) cytotoxicity by M146L-PS1 was inhibited by PTX. It was also highly likely that the involved superoxide-generating enzyme was nitric oxide synthase (NOS), and that the PTX-sensitive cytotoxic signal by M146L-PS1 was mediated by none of the G(i/o) proteins. We conclude that M146L-PS1 activates a NOS-mediated cytotoxic pathway via a novel PTX target.     

Identification of genes expressed preferentially in the honeybee mushroom bodies by combination of differential display and cDNA microarray

To clarify the molecular basis underlying the neural function of the honeybee mushroom bodies (MBs), we identified three genes preferentially expressed in MB using cDNA microarrays containing 480 differential display-positive candidate cDNAs expressed locally or differentially, dependent on caste/aggressive behavior in the honeybee brain. One of the cDNAs encodes a putative type I inositol 1,4,5-trisphosphate (IP(3)) 5-phosphatase and was expressed preferentially in one of two types of intrinsic MB neurons, the large-type Kenyon cells, suggesting that IP(3)-mediated Ca(2+) signaling is enhanced in these neurons.     

Association of plasma viral RNA load with prognosis in cats naturally infected with feline immunodeficiency virus

We measured the quantity of plasma feline immunodeficiency virus (FIV) RNA using a real-time sequence detecting system. Plasma viral RNA load was shown to correlate with the clinical stage, survival time, and disease progression in naturally FIV-infected cats. The present study indicates that the plasma viral RNA load can be used as a clinical marker representing the impairment of the immune system and predicting the clinical outcome in FIV-infected cats.     

Effect of carnosine and related compounds on the inactivation of human Cu,Zn-superoxide dismutase by modification of fructose and glycolaldehyde

Glycolaldehyde, an intermediate of the Maillard reaction, and fructose, which is mainly derived from the polyol pathway, rapidly inactivate human Cu,Zn-superoxide dismutase (SOD) at the physiological concentration. We employed this inactivation with these carbonyl compounds as a model glycation reaction to investigate whether carnosine and its related compounds could protect the enzyme from inactivation. Of eight derivatives examined, histidine, Gly-His, carnosine and Ala-His inhibited the inactivation of the enzyme by fructose (p<0.001), and Gly-His, Ala-His, anserine, carnosine, and homocarnosine exhibited a marked protective effect against the inactivation by glycolaldehyde (p<0.001). The carnosine-related compounds that showed this highly protective effect against the inactivation by glycolaldehyde had high reactivity with glycolaldehyde and high scavenging activity toward the hydroxyl radical as common properties. On the other hand, the carnosine-related compounds that had a protective effect against the inactivation by fructose showed significant hydroxyl radical-scavenging ability. These results indicate that carnosine and such related compounds as Gly-His and Ala-His are effective anti-glycating agents for human Cu,Zn-SOD and that the effectiveness is based not only on high reactivity with carbonyl compounds but also on hydroxyl radical scavenging activity.     

Identification of a toxic mechanism of the plasticizers,phtahlic acid esters,which are putative endocrine disrupters: time-dependent increase in quinolinic acid and its metabolites in rats fed di(2-ethylhexyl)phthalate

We have reported that the administration of di(2-ethylhexyl)phthalate (DEHP) increased the formations of quinolinic acid (QA) and its lower metabolites on the tryptophan-niacin pathway. To discover the mechanism involved in disruption of the tryptophan-niacin pathway by DEHP, we assessed the daily urinary excretion of QA and its lower metabolites, and enzyme activities on the tryptophan-niacin pathway. Rats were fed with a niacin-free, 20% casein diet or the same diet supplemented with 0.1% DEHP or 0.043% phthalic acid and 0.067% 2-ethylhexanol added for 21 days. Feeding of DEHP increased the urinary excretions of QA and its lower metabolites in a time-dependent manner, and the increase of these excretions reached a peak at 11 days, but feeding of phthalic acid and 2-ethylhexanol had no effect. Feeding of DEHP, however, did not affect any enzyme activity including alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), affecting the formation of QA, on the tryptophan-niacin pathway.     

Enzyme inhibitors to increase poly-3-hydroxybutyrate production by transgenic tobacco

Chemical regulation of secondary-metabolite synthesis was investigated through the improvement of poly-3-hydroxybutyrate (PHB) production in transgenic tobacco plants by the use of enzyme inhibitors. Two tobacco lines, BC3 and rCAB8, that produce PHB in both the cytosol and plastids were used. An acetyl-CoA carboxylase inhibitor, D-(+)-Quizalofop-ethyl, increased PHB accumulation in both lines 2-fold. The accumulation rate of plastidial PHB in the rCAB8 line was 2.5-fold higher than that of cytosolic PHB in the BC3 line. A specific inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase, mevastatin, also increased PHB accumulation but only in the BC3 line. These results indicated that chemical regulation of the native metabolic flows by the specific enzyme inhibitors increased secondary-metabolite production in the transgenic tobacco plants we used.