The Ecophysiology of Thiamine Deficiency Complex : Evaluating Sources of Thiaminase in Great Lakes Food Webs

Thiamine (vitamin B₁) is required by all living organisms for carbohydrate metabolism and synthesis of amino acids. Thiamine deficiency is responsible for several related classes of early life stage mortality disorders in salmonines, including Thiamine Deficiency Complex (TDC) in the Laurentian Great Lakes, Cayuga Syndrome in the Finger Lakes, and the M74 in the Baltic Sea. TDC is caused not by lack of sufficient intake of thiamine but rather by a diet rich in prey that contain thiaminase, a thiamine-degrading enzyme. TDC caused by ingestion of thiaminase-containing prey occurs in these wild fish populations and has also been observed in mink, foxes, seals, alligators, chickens, and ruminants. TDC is one of several impediments to rehabilitation of Lake Trout (Salvelinus namaycush), the native apex predator in the Great Lakes. The proximate cause of TDC is known to be the ingestion of prey fish containing high levels of thiaminase, specifically Alewife (Alosa pseudoharengus) and Rainbow Smelt (Osmerus mordax); however, the ultimate source of thiaminase in thiaminase-containing fishes remains unknown. Evaluating potential sources of thiaminase in fishes is essential for understanding thiaminase trophodynamics and developing management strategies for mitigating TDC and facilitating rehabilitation of Lake Trout populations. Thiaminase in prey fishes is hypothesized to originate from two possible sources: either thiaminase-containing fishes acquire thiaminase from their diet (dietary acquisition hypothesis) or thiaminase-containing fishes make the thiaminase enzyme themselves (de novo synthesis hypothesis); these two hypotheses are not mutually exclusive. Chapter 1 describes the causes of TDC and why characterization of the sources of thiaminase in aquatic food webs is necessary. The three primary data chapters presented herein describe whole food web investigations that seek to determine the source of thiaminase in Great Lakes fishes. In Chapter 2, zooplankton were evaluated as a potential source of dietarily acquired thiaminase activity by comparing the thiaminase activity in bulk zooplankton to the zooplankton community composition. Three types of multivariate analysis revealed one candidate source of thiaminase activity, Ploesoma, an omnivorous loricate rotifer. Despite the apparent correlation between Ploesoma biomass and thiaminase activity in bulk zooplankton, Ploesoma spp. constituted sufficiently low biomass that its thiaminase activity would have to be extraordinarily high (i.e., at unprecedented levels) to constitute the major source of thiaminase in Great Lakes food webs. Furthermore, Ploesoma was never observed in the diet of thiaminase-containing fish. Therefore Ploesoma is an unlikely source of thiaminase. No other component of the zooplankton community was consistently related to thiaminase activity. In Chapter 3, the thiaminase activity in fishes was assessed in relation to species, season, depth, and location of capture, and the dietary acquisition hypothesis was assessed directly using stomach content and fatty acid signature analysis. Thiaminase activity was higher in spring than in summer and fall. Round Goby (Neogobius melanostomus) thiaminase activity was higher than previously reported, and Slimy Sculpin (Cottus cognatus) thiaminase activity was highly variable, sometimes exceeding that of Rainbow Smelt. The dietary acquisition hypothesis was evaluated by comparing the thiaminase activity in fish viscera to both the diets and fatty acid signatures of fishes. No compelling evidence that thiaminase activity of fish viscera was consistently the result of consumption of any specific prey taxa was found using three types of multivariate analyses. Indicator Species Analysis suggested Bythotrephes as a potential candidate source of thiaminase, but Bythotrephes was not consumed by some fishes with high thiaminase activity. If the source of thiaminase activity is dietary, the source may be Bythotrephes for some fishes, but those that did not consume Bythotrephes would need to obtain thiaminase from a different source. Fatty acid analysis suggested a moderate tendency for higher thiaminase activity in pelagically-feeding rather than benthically-feeding fishes, but several pelagically feeding fishes contained undetectable thiaminase activity and some benthically feeding fishes contained thiaminase activity comparable to or greater than pelagically feeding fishes. Together, this evidence indicated that no specific prey item was consistently related to thiaminase activity. In Chapter 4, the de novo hypothesis was assessed directly using two approaches. The first approach compared the biochemical characteristics of thiaminases in Alewife, Carp (Cyprinus carpio), quagga mussels (Dreissena rostriformis bugensis), and a bacterium (Paenibacillus thiaminolyticus) that has been isolated from the intestines of Alewife and is known to produce thiaminase. Thiaminases in these four organisms vary in their mass, migration characteristics, tolerance to denaturation, and isoelectric points, suggesting that the source of thiaminase differs in these four taxa. The second approach identified candidate thiaminase genes in fishes using existing information from small peptide fragments from two fish thiaminases from partially purified from Carp and Red Cornetfish (Fistularia petimba). Candidate genes in Carp, Zebrafish (Danio rerio), and Alewife that were homologous to the known peptide fragments were identified, synthesized, and overexpressed. The Zebrafish candidate gene produced an active thiaminase enzyme. This finding confirms de novo synthesis and represents the first report of a thiaminase-encoding protein in any multicellular organism. The candidate gene identified for Alewife is predicted to produce a protein product with biochemical properties that match those determined empirically. The dietary acquisition hypothesis was not well-supported, and findings from Chapters 2 and 3 did not converge as would be expected if the source of thiaminase was dietarily acquired. The potential for de novo synthesis by fishes was confirmed experimentally, which represents the first report of a gene for a thiaminase enzyme from a multicellular animal. Future research should focus on confirming that de novo production accounts for the thiaminase activity in fishes and understanding the physiological factors that lead to increased thiaminase production. This work is relevant to fishery managers in affected ecosystems (Great Lake, Baltic Sea, Finger Lakes, NY) and to biochemists and nutritionist interested in thiamine metabolism

Increasing Thiamine Concentrations in Lake Trout Eggs from Lakes Huron and Michigan Coincide with Low Alewife Abundance

Lake trout Salvelinus namaycush in the Laurentian Great Lakes suffer from thiamine deficiency as a result of adult lake trout consuming prey containing thiaminase, a thiamine-degrading enzyme. Sufficiently low egg thiamine concentrations result in direct mortality of or sublethal effects on newly hatched lake trout fry. To determine the prevalence and severity of low thiamine in lake trout eggs, we monitored thiamine concentrations in lake trout eggs from 15 sites in Lakes Huron and Michigan from 2001 to 2009. Lake trout egg thiamine concentrations at most sites in both lakes were initially low and increased over time at 11 of 15 sites, and the proportion of females with egg thiamine concentrations lower than the recommended management objective of 4 nmol/g decreased over time at eight sites. Egg thiamine concentrations at five of six sites in Lakes Huron and Michigan were significantly inversely related to site-specific estimates of mean abundance of alewives Alosa pseudoharengus, and successful natural reproduction of lake trout has been observed in Lake Huron since the alewife population crashed. These results support the hypothesis that low egg thiamine in Great Lakes lake trout is associated with increased alewife abundance and that low alewife abundance may currently be a prerequisite for successful reproduction by lake trout in the Great Lakes

Detection of Unknown Pregnancy With Complications Using Point-of-Care Ultrasound.

Eclampsia, a condition diagnosed in pre-eclamptic patients who experience seizures, can lead to maternal and fetal death if not treated early. The present case discusses the clinical management of an 18-year-old female who presented to the emergency department (ED) after a generalized tonic-clonic seizure. A physical examination revealed that she was also hypertensive. Based on these symptoms which required urgency due to the patient\u27s instability, and the suspicion that the patient could be pregnant, point-of-care ultrasound (POCUS) was performed. In this case, a POCUS was a faster more accessible modality than a urine or serum human chorionic gonadotropin test. Although the patient denied that she was pregnant, POCUS identified that she was approximately 22-24 weeks pregnant. The patient was promptly diagnosed with eclampsia and given medication to control her blood pressure and seizures. This case highlights the benefits of using POCUS in the ED to expedite clinical decisions by identifying the etiology of a patient\u27s condition and lends itself to the discussion of its utility in a critically ill pregnant woman. It also serves to reinforce the importance of keeping eclampsia as part of an emergency physician\u27s differential when confronted with a potentially pregnant patient with relevant symptoms

Differentiated Smooth Muscle Cells Generate a Subpopulation of Resident Vascular Progenitor Cells in the Adventitia Regulated by Klf4

RATIONALE: The vascular adventitia is a complex layer of the vessel wall consisting of vasa vasorum microvessels, nerves, fibroblasts, immune cells, and resident progenitor cells. Adventitial progenitors express the stem cell markers, Sca1 and CD34 (adventitial sca1-positive progenitor cells [AdvSca1]), have the potential to differentiate in vitro into multiple lineages, and potentially contribute to intimal lesions in vivo. OBJECTIVE: Although emerging data support the existence of AdvSca1 cells, the goal of this study was to determine their origin, degree of multipotency and heterogeneity, and contribution to vessel remodeling. METHODS AND RESULTS: Using 2 in vivo fate-mapping approaches combined with a smooth muscle cell (SMC) epigenetic lineage mark, we report that a subpopulation of AdvSca1 cells is generated in situ from differentiated SMCs. Our data establish that the vascular adventitia contains phenotypically distinct subpopulations of progenitor cells expressing SMC, myeloid, and hematopoietic progenitor-like properties and that differentiated SMCs are a source to varying degrees of each subpopulation. SMC-derived AdvSca1 cells exhibit a multipotent phenotype capable of differentiating in vivo into mature SMCs, resident macrophages, and endothelial-like cells. After vascular injury, SMC-derived AdvSca1 cells expand in number and are major contributors to adventitial remodeling. Induction of the transcription factor Klf4 in differentiated SMCs is essential for SMC reprogramming in vivo, whereas in vitro approaches demonstrate that Klf4 is essential for the maintenance of the AdvSca1 progenitor phenotype. CONCLUSIONS: We propose that generation of resident vascular progenitor cells from differentiated SMCs is a normal physiological process that contributes to the vascular stem cell pool and plays important roles in arterial homeostasis and disease

Do All Stars in the Solar Neighbourhood Form in Clusters?

We present a global study of low mass, young stellar object (YSO) surface densities (Sigma) in nearby (< 500 pc) star forming regions based on a comprehensive collection of Spitzer Space Telescope surveys. We show that the distribution of YSO surface densities is a smooth distribution, being adequately described by a lognormal function from a few to 10^3 YSOs per pc^2, with a peak at ~22 stars pc^-2. The observed lognormal Sigma is consistent with predictions of hierarchically structured star-formation at scales below 10 pc, arising from the molecular cloud structures. We do not find evidence for multiple discrete modes of star-formation (e.g. clustered and distributed). Comparing the observed Sigma distribution to previous Sigma threshold definitions of clusters show that they are arbitrary. We find that only a low fraction (< 26$) of stars are formed in dense environments where their formation/evolution (along with their circumstellar disks and/or planets) may be affected by the close proximity of their low-mass neighbours.Comment: 7 Pages, 2 Figures, JENAM conference (Lisbon

Genome structural variation in Escherichia coli O157:H7

The human zoonotic pathogen Escherichia coli O157:H7 is defined by its extensive prophage repertoire including those that encode Shiga toxin, the factor responsible for inducing life-threatening pathology in humans. As well as introducing genes that can contribute to the virulence of a strain, prophage can enable the generation of large-chromosomal rearrangements (LCRs) by homologous recombination. This work examines the types and frequencies of LCRs across the major lineages of the O157:H7 serotype. We demonstrate that LCRs are a major source of genomic variation across all lineages of E. coli O157:H7 and by using both optical mapping and Oxford Nanopore long-read sequencing prove that LCRs are generated in laboratory cultures started from a single colony and that these variants can be recovered from colonized cattle. LCRs are biased towards the terminus region of the genome and are bounded by specific prophages that share large regions of sequence homology associated with the recombinational activity. RNA transcriptional profiling and phenotyping of specific structural variants indicated that important virulence phenotypes such as Shiga-toxin production, type-3 secretion and motility can be affected by LCRs. In summary, E. coli O157:H7 has acquired multiple prophage regions over time that act to continually produce structural variants of the genome. These findings raise important questions about the significance of this prophage-mediated genome contingency to enhance adaptability between environments

Cell Cycle Regulation and Cytoskeletal Remodelling Are Critical Processes in the Nutritional Programming of Embryonic Development

Many mechanisms purport to explain how nutritional signals during early development are manifested as disease in the adult offspring. While these describe processes leading from nutritional insult to development of the actual pathology, the initial underlying cause of the programming effect remains elusive. To establish the primary drivers of programming, this study aimed to capture embryonic gene and protein changes in the whole embryo at the time of nutritional insult rather than downstream phenotypic effects. By using a cross-over design of two well established models of maternal protein and iron restriction we aimed to identify putative common “gatekeepers” which may drive nutritional programming

Cancer symptom awareness and barriers to symptomatic presentation in England – Are we clear on cancer?

Background: Low cancer awareness may contribute to delayed diagnosis and poor cancer survival. We aimed to quantify socio-demographic differences in cancer symptom awareness and barriers to symptomatic presentation in the English population. Methods: Using a uniquely large data set (n=49?270), we examined the association of cancer symptom awareness and barriers to presentation with age, gender, marital status and socio-economic position (SEP), using logistic regression models to control for confounders. Results: The youngest and oldest, the single and participants with the lowest SEP recognised the fewest cancer symptoms, and reported most barriers to presentation. Recognition of nine common cancer symptoms was significantly lower, and embarrassment, fear and difficulties in arranging transport to the doctor’s surgery were significantly more common in participants living in the most deprived areas than in the most affluent areas. Women were significantly more likely than men to both recognise common cancer symptoms and to report barriers. Women were much more likely compared with men to report that fear would put them off from going to the doctor. Conclusions: Large and robust socio-demographic differences in recognition of some cancer symptoms, and perception of some barriers to presentation, highlight the need for targeted campaigns to encourage early presentation and improve cancer outcomes

Plasma cell-free DNA methylation analysis for ovarian cancer detection: Analysis of samples from a case-control study and an ovarian cancer screening tria

Analysis of cell-free DNA methylation (cfDNAme), alone or combined with CA125, could help to detect ovarian cancers earlier and may reduce mortality. We assessed cfDNAme in regions of ZNF154, C2CD4D and WNT6 via targeted bisulfite sequencing in diagnostic and early detection (preceding diagnosis) settings. Diagnostic samples were obtained via prospective blood collection in cell-free DNA tubes in a convenience series of patients with a pelvic mass. Early detection samples were matched case-control samples derived from the UK Familial Ovarian Cancer Screening Study (UKFOCSS). In the diagnostic set (ncases  = 27, ncontrols  = 41), the specificity of cfDNAme was 97.6% (95% CI: 87.1%-99.9%). High-risk cancers were detected with a sensitivity of 80% (56.3%-94.3%). Combination of cfDNAme and CA125 resulted in a sensitivity of 94.4% (72.7%-99.9%) for high-risk cancers. Despite technical issues in the early detection set (ncases  = 29, ncontrols  = 29), the specificity of cfDNAme was 100% (88.1%-100.0%). We detected 27.3% (6.0%-61.0%) of high-risk cases with relatively lower genomic DNA (gDNA) contamination. The sensitivity rose to 33.3% (7.5%-70.1%) in samples taken <1 year before diagnosis. We detected ovarian cancer in several patients up to 1 year before diagnosis despite technical limitations associated with archival samples (UKFOCSS). Combined cfDNAme and CA125 assessment may improve ovarian cancer screening in high-risk populations, but future large-scale prospective studies will be required to validate current findings

Representations of sport in the revolutionary socialist press in Britain, 1988–2012

This paper considers how sport presents a dualism to those on the far left of the political spectrum. A long-standing, passionate debate has existed on the contradictory role played by sport, polarised between those who reject it as a bourgeois capitalist plague and those who argue for its reclamation and reformation. A case study is offered of a political party that has consistently used revolutionary Marxism as the basis for its activity and how this party, the largest in Britain, addresses sport in its publications. The study draws on empirical data to illustrate this debate by reporting findings from three socialist publications. When sport did feature it was often in relation to high profile sporting events with a critical tone adopted and typically focused on issues of commodification, exploitation and alienation of athletes and supporters. However, readers’ letters, printed in the same publications, revealed how this interpretation was not universally accepted, thus illustrating the contradictory nature of sport for those on the far left