Phytoplankton Relationships to Water Quality in Lake Drummond and Two Drainage Ditches

A twelve-month phytoplankton study was conducted in Lake Drummond and Washington and Jericho Ditches from December 1988 to November 1989. Four dominant phytoplankton groups were identified at these sites. These were the Bacillariophyceae, Cyanophyceae, Cryptophyceae and an autotrophic picoplankton component. Over the past 20 years there has been a decrease in the mean pH levels of Lake Drummond and the replacement of one its former major components, the Chlorophyceae, by the Cyanophyceae. Based on water quality analysis results and species diversity indices, Lake Drummond is classified as in an early eutrophic stage of development

Oxalate metabolism by the acetogenic bacterium Moorella thermoacetica

Whole-cell and cell-extract experiments were performed to study the mechanism of oxalate metabolism in the acetogenic bacterium Moorella thermoacetica. In short-term, whole-cell assays, oxalate consumption was low unless cell suspensions were supplemented with CO2, KNO3, or Na2S2O3. Cell extracts catalyzed the oxalate-dependent reduction of benzyl viologen. Oxalate consumption occurred concomitant to benzyl viologen reduction; when benzyl viologen was omitted, oxalate was not appreciably consumed. Based on benzyl viologen reduction, specific activities of extracts averaged 0.6 μmol oxalate oxidized min−1 mg protein−1. Extracts also catalyzed the formate-dependent reduction of NADP+; however, oxalate-dependent reduction of NADP+ was negligible. Oxalate- or formate-dependent reduction of NAD+ was not observed. Addition of coenzyme A (CoA), acetyl-CoA, or succinyl-CoA to the assay had a minimal effect on the oxalate-dependent reduction of benzyl viologen. These results suggest that oxalate metabolism by M. thermoacetica requires a utilizable electron acceptor and that CoA-level intermediates are not involved

Oxalate metabolism by the acetogenic bacterium Moorella thermoacetica

Whole-cell and cell-extract experiments were performed to study the mechanism of oxalate metabolism in the acetogenic bacterium Moorella thermoacetica. In short-term, whole-cell assays, oxalate consumption was low unless cell suspensions were supplemented with CO2, KNO3, or Na2S2O3. Cell extracts catalyzed the oxalate-dependent reduction of benzyl viologen. Oxalate consumption occurred concomitant to benzyl viologen reduction; when benzyl viologen was omitted, oxalate was not appreciably consumed. Based on benzyl viologen reduction, specific activities of extracts averaged 0.6 μmol oxalate oxidized min−1 mg protein−1. Extracts also catalyzed the formate-dependent reduction of NADP+; however, oxalate-dependent reduction of NADP+ was negligible. Oxalate- or formate-dependent reduction of NAD+ was not observed. Addition of coenzyme A (CoA), acetyl-CoA, or succinyl-CoA to the assay had a minimal effect on the oxalate-dependent reduction of benzyl viologen. These results suggest that oxalate metabolism by M. thermoacetica requires a utilizable electron acceptor and that CoA-level intermediates are not involved

Laboratory Photo-chemistry of PAHs: Ionization versus Fragmentation

Interstellar polycyclic aromatic hydrocarbons (PAHs) are expected to be strongly processed by vacuum ultraviolet photons. Here, we report experimental studies on the ionization and fragmentation of coronene (C24H12), ovalene (C32H14) and hexa-peri-hexabenzocoronene (HBC; C42H18) cations by exposure to synchrotron radiation in the range of 8--40 eV. The results show that for small PAH cations such as coronene, fragmentation (H-loss) is more important than ionization. However, as the size increases, ionization becomes more and more important and for the HBC cation, ionization dominates. These results are discussed and it is concluded that, for large PAHs, fragmentation only becomes important when the photon energy has reached the highest ionization potential accessible. This implies that PAHs are even more photo-stable than previously thought. The implications of this experimental study for the photo-chemical evolution of PAHs in the interstellar medium are briefly discussed

Engaged in Research/Achieving Balance: A Case Example of Teaching Research to Masters of Social Work Students

This article considers the use of participatory action research and Photovoice as a tool for engaging graduate level social work students in research education. Photovoice is an investigative tool that assists people in critically reflecting on the everyday social and political realities of their lives, enriching their understanding of their communities and the issues pertinent to them, while at the same time, giving them a voice from which to educate others on these issues. In the context of a group assignment, 26 social work students, enrolled in an introductory graduate research course, were asked to reflect upon the question, “What does balance look like for you in the MSW program?” Thirty-two photographs with captions were submitted and analyzed by class members for relevant themes. Balance was described as existing along a continuum from balanced to unbalanced and was comprised of four major themes: connection, nurturance, keeping perspective, and disengagement. Although this teaching strategy was not formally assessed, preliminary impressions are that students benefited from participating in the Photovoice activity

DNA copy number changes define spatial patterns of heterogeneity in colorectal cancer

Genetic heterogeneity between and within tumours is a major factor determining cancer progression and therapy response. Here we examined DNA sequence and DNA copy-number heterogeneity in colorectal cancer (CRC) by targeted high-depth sequencing of 100 most frequently altered genes. In 97 samples, with primary tumours and matched metastases from 27 patients, we observe inter-tumour concordance for coding mutations; in contrast, gene copy numbers are highly discordant between primary tumours and metastases as validated by fluorescent in situ hybridization. To further investigate intra-tumour heterogeneity, we dissected a single tumour into 68 spatially defined samples and sequenced them separately. We identify evenly distributed coding mutations in APC and TP53 in all tumour areas, yet highly variable gene copy numbers in numerous genes. 3D morpho-molecular reconstruction reveals two clusters with divergent copy number aberrations along the proximal–distal axis indicating that DNA copy number variations are a major source of tumour heterogeneity in CRC

Anomalously High Recruitment of the 2010 Gulf Menhaden (Brevoortia patronus) Year Class: Evidence of Indirect Effects from the Deepwater Horizon Blowout in the Gulf of Mexico

Gulf menhaden (Brevoortia patronus) exhibited unprecedented juvenile recruitment in 2010 during the year of the Deepwater Horizon well blowout, exceeding the prior 39-year mean by more than four standard deviations near the Mississippi River. Abundance of that cohort remained exceptionally high for two subsequent years as recruits moved into older age classes. Such changes in this dominant forage fish population can be most parsimoniously explained as consequences of release from predation. Contact with crude oil induced high mortality of piscivorous seabirds, bottlenose dolphin (Tursiops truncatus), waders, and other fish-eating marsh birds, all of which are substantial consumers of Gulf menhaden. Diversions of fresh water from the Mississippi River to protect coastal marshes from oiling depressed salinities, impairing access to juvenile Gulf menhaden by aquatic predators that avoid low-salinity estuarine waters. These releases from predation led to an increase of Gulf menhaden biomass in 2011 to 2.4 million t, or more than twice the average biomass of 1.1 million t for the decade prior to 2010. Biomass increases of this magnitude in a major forage fish species suggest additional trophically linked effects at the population-, trophic-level and ecosystem scales, reflecting an heretofore little appreciated indirect effect that may be associated with major oil spills in highly productive marine waters