(Re)Moralizing the suicide debate

Contemporary approaches to the study of suicide tend to examine suicide as a medical or public health problem rather than a moral problem, avoiding the kinds of judgements that have historically characterised discussions of the phenomenon. But morality entails more than judgement about action or behaviour, and our understanding of suicide can be enhanced by attending to its cultural, social, and linguistic connotations. In this work, I offer a theoretical reconstruction of suicide as a form of moral experience that delineates five distinct, yet interrelated domains of understanding – the temporal, the relational, the existential, the ontological, and the linguistic. Attention to each of these domains, I argue, not only enriches our understanding of the moral realm, but provides a heuristic for examining the moral traditions and practices which constitute contemporary understandings of suicide. Keywords: Suicide; philosophy; social values; humanitie

Effects of brown tide (Aureococcus anophagefferens) on hard clam, Mercenaria mercenaria, larvae and implications for benthic recruitment

Brown tides of Aureococcus anophagefferens occur in shallow mid-Atlantic bays in the USA and attain peak summer densities of ~1000 to 2800 cells \uc2\ub5l\u20131. Blooms coincide with the period of spawning and planktotrophic larval development of the hard clam Mercenaria mercenaria, a commercially important bivalve in the region. This laboratory study investigates the effects of A. anophagefferens (toxic isolate from Provasoli-Guillard Center for Culture of Marine Phytoplankton [CCMP 1708]) on hard clams throughout their larval development as a function of increasing (1) supplement and (2) contributor to total phytoplankton cell volume in the diet. Brown tide consistently inhibited veliger growth rates in a dose-dependent manner, leading to arrested development in the D-stage; yet mortalities varied greatly among larval batches and were attributed to secondary effects of nutritional stress. Growth of larvae exposed for 2 wk to brown tide at 800 cells \uc2\ub5l\u20131 was 89 to 90% less than controls fed Isochrysis galbana (clone T-iso) in both the presence and absence of alternate food. No recovery was observed when larvae were returned to the control diet. However, larvae showed variable intrapopulation susceptibility to brown tide when exposed to a mixed suspension of A. anophagefferens and I. galbana (400 and 50 cells \uc2\ub5l\u20131, respectively). Exposure to low levels of brown tide (50 cells \uc2\ub5l\u20131) resulted in relatively small but significant growth reduction. Larvae had reduced larval clearance rates (ingestion) when exposed to unialgal brown tide, as confirmed by analysis of gut autofluorescence and negative feeding selectivity for A. anophagefferens in a mixed suspension. Therefore, primarily through their inhibitory effects on growth, brown tides at ?200 cells \uc2\ub5l\u20131 are expected to cause metamorphic failure of hard clam larval populations. These will lead to extended larval life in the plankton and increased vulnerability to secondary mortality factors. In turn, hard clam larvae are expected to make a negligible contribution to microzooplankton grazing on brown tide.Peer reviewed: YesNRC publication: Ye

Effects of brown tide (Aureococcus anophagefferens) on hard clam, Mercenaria mercenaria, larvae and implications for benthic recruitment

Brown tides of Aureococcus anophagefferens occur in shallow mid-Atlantic bays in the USA and attain peak summer densities of ~1000 to 2800 cells \uc2\ub5l\u20131. Blooms coincide with the period of spawning and planktotrophic larval development of the hard clam Mercenaria mercenaria, a commercially important bivalve in the region. This laboratory study investigates the effects of A. anophagefferens (toxic isolate from Provasoli-Guillard Center for Culture of Marine Phytoplankton [CCMP 1708]) on hard clams throughout their larval development as a function of increasing (1) supplement and (2) contributor to total phytoplankton cell volume in the diet. Brown tide consistently inhibited veliger growth rates in a dose-dependent manner, leading to arrested development in the D-stage; yet mortalities varied greatly among larval batches and were attributed to secondary effects of nutritional stress. Growth of larvae exposed for 2 wk to brown tide at 800 cells \uc2\ub5l\u20131 was 89 to 90% less than controls fed Isochrysis galbana (clone T-iso) in both the presence and absence of alternate food. No recovery was observed when larvae were returned to the control diet. However, larvae showed variable intrapopulation susceptibility to brown tide when exposed to a mixed suspension of A. anophagefferens and I. galbana (400 and 50 cells \uc2\ub5l\u20131, respectively). Exposure to low levels of brown tide (50 cells \uc2\ub5l\u20131) resulted in relatively small but significant growth reduction. Larvae had reduced larval clearance rates (ingestion) when exposed to unialgal brown tide, as confirmed by analysis of gut autofluorescence and negative feeding selectivity for A. anophagefferens in a mixed suspension. Therefore, primarily through their inhibitory effects on growth, brown tides at ?200 cells \uc2\ub5l\u20131 are expected to cause metamorphic failure of hard clam larval populations. These will lead to extended larval life in the plankton and increased vulnerability to secondary mortality factors. In turn, hard clam larvae are expected to make a negligible contribution to microzooplankton grazing on brown tide.Peer reviewed: YesNRC publication: Ye

Concentration-dependent effects of toxic and non-toxic isolates of the brown tide alga Aureococcus anophagefferens on growth of juvenile bivalves

Suspension-feeding bivalve mollusks are highly susceptible to the deleterious effects of blooms of the picoplankter Aureococcus anophagefferens (brown tide) in coastal bays of the mid- Atlantic USA. Although short-term exposure to A. anophagefferens is known to cause feeding inhibition of bivalves, longer-term effects on growth and survival are poorly documented. This laboratory study examines the concentration-dependent effects of 2 Long Island, New York, isolates of A. anophagefferens on the juvenile hard clam Mercenaria mercenaria and the mussel Mytilus edulis. Concentrations =400 \uc3\u2014 103 cells ml\u20131 of a toxic A. anophagefferens isolate (CCMP 1708) arrested shell growth and caused significant soft-tissue weight loss and reduced condition in both species, effects comparable to those of starvation, but did not induce mortalities over the 3 wk study period. No histopathology was detected at the cellular level; brown tide caused reduction in digestive epithelium height and overall appearance of absorptive cells similar to that observed under starvation. Optimum concentrations of non-toxic, nutritious algae in a mixed assemblage with A. anophagefferens CCMP 1708 did not mitigate effects of brown tide at 400 \uc3\u2014 103 cells ml\u20131, but at 80 \uc3\u2014 103 A. anophagefferens cells ml\u20131 the mixture resulted in positive growth and progressive acclimation to the diet. In contrast, exposure of hard clams to 400 \uc3\u2014 103 and 1 \uc3\u2014 106 cells ml\u20131 of a non-toxic A. anophagefferens strain (CCMP 1784) supported growth rates only 18 and 29% below a volume-equivalent control diet of Isochrysis galbana respectively. We thus conclusively demonstrate that the detrimental effects of brown tide on bivalve growth are mainly attributable to cell toxicity, rather than high cell density, nutritional deficiency or poor retention of small (2 \uc2\ub5m) cells. The implications of these results to recruitment success and stock-enhancement efforts of bivalve populations in brown tide-affected estuaries are discussed.Peer reviewed: YesNRC publication: Ye

Real-time monitoring, diagnosis, and time-course analysis of microalgae Scenedesmus AMDD cultivation using dual excitation wavelength fluorometry

Dual excitation wavelength fluorometry was used for real-time monitoring and diagnosis of the growth of the microalgae Scenedesmus AMDD in a 300-L continuous photobioreactor (PBR). Emission spectra were acquired at 1-min intervals using excitation lights at 365 and 540 nm. Real-time dry weight estimations were achieved using linear regression with the chlorophyll peak, while protein estimations required a more complex Principal Component Regression model, which takes advantage of the full emission spectrum. The resulting regression coefficients were 0.95 and 0.80, respectively. Furthermore, the spectra were analyzed using multivariate curve resolution technique. The proposed approach for fluorescence-based, real-time measurements of key algae cultivation parameters and culture state diagnosis was successfully demonstrated in a 42-day PBR validation test.Peer reviewed: YesNRC publication: Ye

Sodium channel mutation responsible for saxitoxin resistance in clams increases risk of PSP

Bivalve molluscs, the primary vectors of paralytic shellfish poisoning (PSP) in humans, show marked inter-species variation in their capacity to accumulate PSP toxins (PSTs)1 which has a neural basis2, 3. PSTs cause human fatalities by blocking sodium conductance in nerve fibres4, 5. Here we identify a molecular basis for inter-population variation in PSP resistance within a species, consistent with genetic adaptation to PSTs. Softshell clams (Mya arenaria) from areas exposed to 'red tides' are more resistant to PSTs, as demonstrated by whole-nerve assays, and accumulate toxins at greater rates than sensitive clams from unexposed areas. PSTs lead to selective mortality of sensitive clams. Resistance is caused by natural mutation of a single amino acid residue, which causes a 1,000-fold decrease in affinity at the saxitoxin-binding site in the sodium channel pore of resistant, but not sensitive, clams. Thus PSTs might act as potent natural selection agents, leading to greater toxin resistance in clam populations and increased risk of PSP in humans. Furthermore, global expansion of PSP to previously unaffected coastal areas6 might result in long-term changes to communities and ecosystems.Peer reviewed: YesNRC publication: Ye

A Rat Study to Evaluate the Protein Quality of Three Green Microalgal Species and the Impact of Mechanical Cell Wall Disruption

The present study was conducted to evaluate the protein quality of microalgae species Chlorella vulgaris (CV), Chlorella sorokiniana (CS), and Acutodesmus obliquus (AO) and assess the impact of mechanical cell wall disruption. Male Sprague–Dawley rats, around 156 g after adaptation, were placed in metabolic cages and fed experimental diets that were either protein-free or contained 10% protein solely from one of the undisrupted or disrupted CV, CS, and AO. After 3 days, feces were collected for a period of 5 days and analyzed together with diet samples for crude protein contents. Apparent protein digestibility, true protein digestibility, amino acid score, and protein digestibility-corrected amino acid score were calculated. In vitro protein digestibility was measured using the pepsin–pancreatin method and the in vitro protein digestibility-corrected amino acid score was calculated. The crude protein contents of CV, CS, and AO were 53.5, 50.2, and 40.3%, respectively. The amino acid score of the first limiting amino acid was 1.10, 1.27, and 0.86, true protein digestibility was 64.7, 59.3, and 37.9% and protein digestibility-corrected amino acid score was 0.63, 0.64, and 0.29, respectively, for CV, CS, and AO. Mechanical cell disruption significantly improved protein digestibility without a substantial impact on the amino acid profile and score, resulting in the increase of protein digestibility-corrected amino acid score to 0.77, 0.81, and 0.46, respectively, for disrupted CV, CS, and AO. There was a strong correlation between in vitro protein digestibility and apparent protein digestibility (r = 0.986), and also between in vitro protein digestibility-corrected amino acid score and in vivo protein digestibility-corrected amino acid score (r = 0.994). The results suggest that the CV and CS are acceptable sources of protein for humans and animals and quality can be markedly improved by mechanical cell wall disruption. Additionally, in vitro protein digestibility measured using the pepsin–pancreatin method may be used to screen protein product candidates, save animals, reduce cost, and accelerate product development

Mixotrophic and photoautotrophic cultivation of 14 microalgae isolates from Saskatchewan, Canada : potential applications for wastewater remediation for biofuel production

Northern regions are generally viewed as unsuitable for microalgal biofuel production due to unfavorable climate and solar insolation levels. However, these conditions can potentially be mitigated by coupling microalgal cultivation to industrial processes such as wastewater treatment. In this study, we have examined the biomass and lipid productivity characteristics of 14 microalgae isolates (Chlorophyta) from the Canadian province of Saskatchewan. Under both photoautotrophic and mixotrophic cultivation, a distinct linear trend was observed between biomass and lipid productivities in the 14 SK isolates. The most productive strain under cultivation in TAP media was Scenedesmus sp.-AMDD which displayed rates of biomass and fatty acid productivities of 80 and 30.7 mg L-1 day-1, respectively. The most productive strain in B3NV media was Chlamydomonas debaryana-AMLs1b which displayed rates of biomass and fatty acid productivities of 51.7 and 5.9 mg L-1 day-1, respectively. In 11 of the isolates tested, secondary municipal wastewater (MCWW) supported rates of biomass productivity between 21 and 33 mg L-1 day-1 with Scenedesmus sp.-AMDD being the most productive. Three strains, Chlamydomonas debaryana-AMB1, Chlorella sorokiniana-RBD8 and Micractinium sp.-RB1b, showed large increases in biomass productivity when cultivated mixotrophically in MCWW supplemented with glycerol. High relative oleic acid content was detected in 10 of the 14 isolates when grown mixotrophically in media supplemented with acetate. There was no detectable effect on the fatty acid profiles in cells cultivated mixotrophically in glycerol-supplemented MCWW. These data indicate that biomass and lipid productivities are boosted by mixotrophic cultivation. Exploiting this response in municipal wastewater is a promising strategy for the production of environmentally sustainable biofuels.Peer reviewed: YesNRC publication: Ye