Urea uptake and urease activity in the Chesapeake Bay

The importance of urea in supplying the nitrogen (N) required by planktonic communities has long been recognized, notably by James J. McCarthy in studies as early as the 1970s. Utilization of urea involves a two-step enzymatic process in phytoplankton, with urea first entering the cell via transport (i.e., urea uptake), followed by the conversion of urea into ammonium by the enzyme urease. This article describes a series of field observations and experiments conducted in the Chesapeake Bay, USA, from 2001 through 2018, aimed at understanding the relationship between urea uptake and urease activity and the role of environmental factors on that relationship. Principal component analysis revealed a few patterns. Urea uptake, for example, was consistently positively related to combined variables that included urea concentrations. Similarly, urease activity was consistently positively related to combined variables that included temperature. Contrary to findings in culture studies, however, relationships with environmental factors within different phytoplankton taxa in the field were not clear. This suggests that factors other than those examined may be involved in the regulation of urea uptake and urease activity. New insights into the role of the urea cycle in phytoplankton nitrogen dynamics suggest that the regulation of urease may not be directly impacted by environmental factors, but indirectly regulated by different metabolic pathways responding to nutrient availability, light, and temperature conditions

Avery Brundage and the 1936 Olympic Games

When Hitler came to power, the Olympic Games had already been awarded to Germany. In the early phase of Nazi rule, Jews were expelled from sport clubs, making it impossible for them to train for, or participate in, the 1936 Olympics. The Amateur Athletic Union and American Olympic Committee, the organizations responsible for sending a U.S. team to Germany, were worried about the racist policies of the new regime. Despite a German pledge of non-discrimination made to the International Olympic Committee in 1933, the AAU and AOC passed resolutions making American participation contingent upon the cessation of discrimination against German-Jewish athletes. Discriminatory practices did, however, continue. Meanwhile, German officials in charge of the Games' preparations received continual pressure from Hitler to secure American presence at the Games. The boycott movement in the United States did, in the end, fail; but not because of German pressure. It failed primarily because of the personal intervention of AOC president Avery Brundage. Brundage, as well as other well-connected Olympic officials, had the opportunity to let the AAU and AOC determine American participation on the basis of an accurate assessment of the German-Jewish situation. Instead, they deliberately misled the two organizations and world public opinion by giving assurances they knew were false

Regulation of estuarine phytoplankton and bacterial urea uptake and urease activity by environmental factors

The regulation by environmental factors of two enzymes involved with urea utilization - urea transport and urease - in estuarine phytoplankton and bacteria was studied in cultures of five phytoplankton species, in Chesapeake Bay and Choptank River assemblages, and in bioassay and mesocosm experiments. In these experiments, temperature and nitrogen availability (NO sub 3 minus, NH sub 4 plus, and urea) were found to regulate urea uptake and urease activity. However, regulation by these environmental factors was dependent on the composition of the plankton community. Dinoflagellates were found to have the highest urease activity in culture among five phytoplankton species (Prorocentrum minimum, Karlodinium veneficum, Heterocapsa triquetra, Storeatula major, and Isochrysis sp.) in culture on a per cell and per cell volume basis with an optimized method to measure urease activity. Urease activity was also lower when the dinoflagellates were grown on NH sub 4 plus than when grown on NO sub 3 minus or urea, suggesting repression by NH sub 4 plus. Higher rates of urea uptake and urease activity in Chesapeake Bay and the Choptank River were often associated with the presence of dinoflagellates and cyanobacteria during the warmer months. Rates were also higher under N-limitation when these phytoplankton were present than under P-limitation when diatoms were present. Rates of urea uptake and urease activity in natural assemblages were repressed when NO sub 3 minus and NH sub 4 plus concentrations exceeded 40 and 5 ug at N l to the negative 1, respectively. Rates of urea uptake and urease activity decreased in response to additions of NH sub 4 plus in bioassay and mesocosm experiments. In these experiments, dinoflagellates had the highest urea uptake and urease activity on a per cell basis while cyanobacteria had the highest urea uptake and urease activity on a per cell volume or per chlorophyll a basis. The difference in regulation of urea uptake and urease activity among the diatoms, dinoflagellates and cyanobacteria provide some biochemical explanantions about how they utilize urea under contrasting environmental conditions

The Opioid Crisis

Opioid use and addiction have reached epidemic proportions in Philadelphia, making drug overdose involving opioids a leading cause of death. Both pharmaceutical and illicit opioids contribute to this crisis. Opioid sales in Philadelphia more than doubled between 2000 and 2012, and health care providers continue to prescribe opioid pain medication in greater quantities than medically appropriate. The peak age group for overdoses is 45-54, an older age group than previously seen. Over-prescribing of opioids contributes to the recruitment of adults into drug dependence. While use of opioid pain medications usually does not lead to opioid use disorder, four out of five heroin users nationwide transitioned from original use of prescription medications. Heroin is easy to obtain, potent and cheap compared to prescription pain medications. There are estimated to be at least 70,000 heroin users in Philadelphia.https://repository.upenn.edu/publichealth_databriefs/1003/thumbnail.jp

Composing Through the Transformation Technique

This project paper is an investigation of how language teachers can effectively utilise transformations of stories to motivate students to generate ideas, and write creatively a story of their own using what they have read as a guide or model. Twenty form one volunteers wrote two transformations based on the original story, "The Silkie". The transformations were then compared with the original story in terms of changes made. This study indicates that transformations can be used in Malaysia as a means to motivate ESL students to generate ideas and increase their fluency in writing as students wrote interesting stories of their own using culturally familiar ideas. This study also reveals that students can be trained to write, if fluency and not correctness is emphasised in the writing classroom

MAP1B Interaction with the FW Domain of the Autophagic Receptor Nbr1 Facilitates Its Association to the Microtubule Network

Selective autophagy is a process whereby specific targeted cargo proteins, aggregates, or organelles are sequestered into double-membrane-bound phagophores before fusion with the lysosome for protein degradation. It has been demonstrated that the microtubule network is important for the formation and movement of autophagosomes. Nbr1 is a selective cargo receptor that through its interaction with LC3 recruits ubiquitinated proteins for autophagic degradation. This study demonstrates an interaction between the evolutionarily conserved FW domain of Nbr1 with the microtubule-associated protein MAP1B. Upon autophagy induction, MAP1B localisation is focused into discrete vesicles with Nbr1. This colocalisation is dependent upon an intact microtubule network as depolymerisation by nocodazole treatment abolishes starvation-induced MAP1B recruitment to these vesicles. MAP1B is not recruited to autophagosomes for protein degradation as blockage of lysosomal acidification does not result in significant increased MAP1B protein levels. However, the protein levels of phosphorylated MAP1B are significantly increased upon blockage of autophagic degradation. This is the first evidence that links the ubiquitin receptor Nbr1, which shuttles ubiquitinated proteins to be degraded by autophagy, to the microtubule network

Assessing the reliability of ecotoxicological studies : an overview of current needs and approaches

In general, reliable studies are well designed and well performed, and enough details on study design and performance are reported to assess the study. For hazard and risk assessment in various legal frameworks, many different types of ecotoxicity studies need to be evaluated for reliability. These studies vary in study design, methodology, quality, and level of detail reported (e.g., reviews, peer-reviewed research papers, or industry-sponsored studies documented under Good Laboratory Practice [GLP] guidelines). Regulators have the responsibility to make sound and verifiable decisions and should evaluate each study for reliability in accordance with scientific principles regardless of whether they were conducted in accordance with GLP and/or standardized methods. Thus, a systematic and transparent approach is needed to evaluate studies for reliability. In this paper, 8 different methods for reliability assessment were compared using a number of attributes: categorical versus numerical scoring methods, use of exclusion and critical criteria, weighting of criteria, whether methods are tested with case studies, domain of applicability, bias toward GLP studies, incorporation of standard guidelines in the evaluation method, number of criteria used, type of criteria considered, and availability of guidance material. Finally, some considerations are given on how to choose a suitable method for assessing reliability of ecotoxicity studies. Integr Environ Assess Manag 2017;13:640-651. (c) 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC