The inhibitory effects of free nitrous acid on the energy generation and growth processes of an enriched Nitrobacter culture

The inhibitory effects of nitrite (NO2-)/free nitrous acid (HNO2-FNA) on the metabolism of Nitrobacter were investigated using a method allowing the decoupling of the growth and energy generation processes. A lab-scale sequencing batch reactor was operated for the enrichment of a Nitrobacter culture. Fluorescent in situ hybridization (FISH) analysis showed that 73% of the bacterial population was Nitrobacter. Batch tests were carried out to assess the oxygen and nitrite consumption rates of the enriched culture at low and high nitrite levels, in the presence or absence of inorganic carbon. It was observed that in the absence of CO2, the Nitrobacter culture was able to oxidize nitrite at a rate that is 76% of that in the presence of CO2, with an oxygen consumption rate that is 85% of that measured in the presence of CO2. This enabled the impacts of nitrite/FNA on the catabolic and anabolic processes of Nitrobacter to be assessed separately. FNA rather than nitrite was likely the actual inhibitor to the Nitrobacter metabolism. It was revealed that FNA of up to 0.05 mg HNO2-N center dot L-1 (3.4 mu M), which was the highest FNA concentration used in this study, did not have any inhibitory effect on the catabolic processes of Nitrobacter. However, FNA initiated its inhibition to the anabolic processes of Nitrobacter at approximately 0.011 mg HNO2-N center dot L-1 (0.8 mu M), and completely stopped biomass synthesis at a concentration of approximately 0.023 mg HNO2-N center dot L-1 (1.6 mu M). The inhibitory effect could be described by an empirical inhibitory model proposed in this paper, but the underlying mechanisms remain to be revealed.

Isolation and characterization of microsatellite loci from Macadamia

Thirty-three microsatellite loci were isolated for the Australian rainforest tree Macadamia integrifolia. Genotyping across a test panel of 43 commercial cultivars generated an average polymorphic information content of 0.480. Five loci showed no polymorphism across cultivars. Significant linkage disequilibrium was detected in 10 pairwise comparisons, including two pairs of loci identified from the same clone sequence. The 33 microsatellite loci represent a significant tool for genome mapping and population genetic studies.

Polymorphic microsatellite loci for the zebra shark Stegostoma fasciatum

We report on the development and characterization of 14 polymorphic microsatellite loci in the zebra shark (Stegostoma fasciatum). Five tetranucleotide and nine dinucleotide loci were polymorphic with heterozygosities ranging from 0.400 to 0.967 and from three to 22 alleles per locus. Cross-species amplification of these zebra shark primers on four other species of orectolobid sharks was not successful.

Obtaining highly enriched cultures of candidatus accumulibacter phosphates through alternating carbon sources

Candidatus Accumulibacter Phosphatis is widely considered to be a polyphosphate accumulating organism (PAO) of prime importance in enhanced biological phosphorus removal (EBPR) systems. This organism has yet to be isolated, despite many attempts. Previous studies on the biochemical and physiological aspects of this organism, as well as its response to different EBPR operational conditions, have generally relied on the use of mixed culture enrichments. One frequent problem in obtaining highly enriched cultures of this organism is the proliferation of glycogen accumulating organisms (GAO) that can compete with PAOs for limited carbon sources under similar operational conditions. In this study, Candidatus Accumulibacter Phosphatis has been enriched in a lab-scale bioreactor to a level greater than 90% as quantified by fluorescence in situ hyrbridisation (FISH). This is the highest enrichment of this organism that has been reported thus far, and was obtained by alternating the sole carbon source in the feed between acetate and propionate every one to two sludge ages, and operating the bioreactor within a pH range of 7.0-8.0. Simultaneously, the presence of two known groups of GAOs was eliminated under these operational conditions. Excellent phosphorus removal performance and stability were maintained in this system, where the phosphorous concentration in the effluent was below 0.2 mg/L for more than 7 months. When a disturbance was introduced to this system by adding sludge from an enriched GAO culture, Candidatus Accumulibacter Phosphatis once again became highly enriched, while the GAOs were out-competed. This feeding strategy is recommended for future studies focused on describing the physiology and biochemistry of Accumulibacter, where a highly-enriched culture of this organism is of high importance. (c) 2006 Elsevier Ltd. All rights reserved.

Evidence for microsatellite instability in bilateral breast carcinomas

The molecular pathogenesis of various categories of breast cancer (BC) has been well described, but surprisingly few reports have appeared on analysis of somatic mutations in bilateral BC. We have performed a polymerase chain reaction (PCR)-driven investigation of chromosomal regions showing common loss of heterozygosity (LOH) in 23 cases (46 rumors) from patients diagnosed with bilateral BC, LOH was observed in 15/46 (33%) informative tumors for chromosome 1p, 5/32 (16%) for 5q, 12/44 (27%) for 11q, 15/40 (38%) for 13q and 4/24 (17%) for 17p. These values are within the range of interlaboratory variations reported fur unilateral BC, There was no strong evidence for concordance of LOH within the same patient for any of the chromosomal loci tested. Atypical for breast carcinomas, 7/46 (15%) turners accumulated a high frequency (ranging from 11 to 29%) of shortened dinucleotide CA repeats, implying microsatellite instability (MI). Further analysis with the highly informative BAT-26 marker allowed for the classification of two of these tumors as having a replication error positive (RER+/MSI-H) phenotype, whereas the remaining five carcinomas harbored so-called borderline MI. Thus an involvement of both RER+ and borderline MI appears to be a distinct feature of bilateral breast carcinomas compared to unilateral lesions. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.