Abstract
This study investigated impacts of the algal toxin domoic acid (DA) on copepods in Scottish waters. Inspection of seasonal patterns revealed that several common copepods (Acartia spp. Dana, ...1846, Calanus spp. Leach, 1816, Centropages spp. Krøyer, 1849, Pseudocalanus spp. Boeck, 1872, and Temora longicornis (Müller O.F., 1785)) regularly coexist with potentially toxic species from the diatom genus Pseudo-nitzschia H. Peragallo in H. Peragallo and M Peragallo, 1900. A short field study investigating the DA content of Calanus spp. at the Scottish Coastal Observatory site at Stonehaven recorded DA during every sampling event. The highest DA levels were associated with a July bloom (∼135000 cells L−1) of Pseudo-nitzschia cf. plurisecta Orive & Pérez-Aicua 2013. Several studies have previously investigated effects of ingested DA on copepods but information on effects of dissolved DA is lacking, therefore, simple exposure experiments were carried out to measure mortality of copepod species at ecologically relevant concentrations of dissolved DA. The highest concentrations tested (≥ 50 ng DA mL−1) decreased survival in Temora longicornis only; survival of other copepod species was unaffected. However, T. longicornis feeding on non-toxic algae in the presence of dissolved DA did not accumulate DA in their tissue. This study provides evidence of the potential for Calanus spp. to act as vectors for DA to higher trophic levels in Scottish waters.
This analysis of notified syphilis cases in Victoria, Australia between 2015 and 2018 shows the syphilis epidemic in Victoria has become more generalised, with increases among heterosexual men and ...women residing in outer Melbourne suburbs - areas that differ from those of gay men.
Marine copepods are central to the productivity and biogeochemistry of marine ecosystems. Nevertheless, the direct and indirect effects of climate change on their metabolic functioning remain poorly ...understood. Here, we use metabolomics, the unbiased study of multiple low molecular weight organic metabolites, to examine how the physiology of Calanus spp. is affected by end-of-century global warming and ocean acidification scenarios. We report that the physiological stresses associated with incubation without food over a 5-day period greatly exceed those caused directly by seawater temperature or pH perturbations. This highlights the need to contextualise the results of climate change experiments by comparison to other, naturally occurring stressors such as food deprivation, which is being exacerbated by global warming. Protein and lipid metabolism were up-regulated in the food-deprived animals, with a novel class of taurine-containing lipids and the essential polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid and docosahexaenoic acid, changing significantly over the duration of our experiment. Copepods derive these PUFAs by ingesting diatoms and flagellated microplankton respectively. Climate-driven changes in the productivity, phenology and composition of microplankton communities, and hence the availability of these fatty acids, therefore have the potential to influence the ability of copepods to survive starvation and other environmental stressors.
Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean. The rate at which the sinking carbon is ...converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink.
•IL-35 was found to be expressed mainly by epithelial derived PCAN cells in vivo.•IL-35 promoted growth and inhibited apoptosis in PCAN cell lines in vitro.•IL-35 might function as an autocrine ...growth factor in PCAN growth.
Interleukin-35 (IL-35), an IL-12 cytokine family member, mediates the immune inhibitory function of regulatory T cells (Treg). We assayed the presence of IL-35 in paraffin-embedded human pancreas cancer (PCAN) and unexpectedly found IL-35 was expressed mainly by epithelial derived PCAN cells, but not by Treg. We further examined the expression and effect of exogenous IL-35 in human PCAN cell lines and found IL-35 promoted growth and inhibited apoptosis in PCAN cell lines. IL-35 induced proliferation correlated with an increase in cyclin B, cyclin D, cdk2, and cdk4 and a decrease in p27 expression, while inhibition of apoptosis was associated with an increase in Bcl-2 and a decrease in TRAILR1. We conclude IL-35 is produced by PCAN in vivo and promotes PCAN cell line growth in vitro. These results might indicate an important new role for IL-35 as an autocrine growth factor in PCAN growth.
•Calanus helgolandicus clearance rates ranged between 30 and 176 ml copepod−1 day−1.•Ingestion rates ranged between 8.6–17.9 μg C copepod−1day−1.•Clearance and ingestion declined as toxic Alexandrium ...catenella increased in diet.•Egg production and viability were unaffected despite increase in toxic A. catenella.•Body toxin concentrations: 3.6–365.6 pg diHCl STX eq. copepod−1; 0.02–3.3 % retained.
Copepods of the genus Calanus dominate the biomass of pelagic ecosystems from the Mediterranean Sea up into the Arctic Ocean and form an important link between phytoplankton and higher trophic levels. Impacts from toxin-producing harmful algae (HA) have been recorded throughout this region over the last 50 years, with potentially negative effects on Calanus spp. populations and the ecosystem functions and services they provide. Here we examine how ingestion, egg-production and egg-viability in Calanus helgolandicus are affected by the relative abundance of the toxin-producing dinoflagellate Alexandrium catenella in their diet. Our four-day experiments demonstrate that the ingestion rate of C. helgolandicus declined significantly as the percentage of toxin-producing A. catenella within their diet increased, whereas egg production and egg viability were unaffected. Toxin profile concentrations for A. catenella are presented alongside body toxin-loads in C. helgolandicus after 4 days of feeding on these cells. The body toxin concentrations of C. helgolandicus were 3.6–356.6 pg STX diHCl eq. copepod−1, approximately 0.02–3.3 % of the toxins ingested. Our work suggests that the effects of exposure to A. catenella may be negligible in the short-term but could manifest if bloom conditions persist for longer than our experimental duration.
The changing Arctic environment is affecting zooplankton that support its abundant wildlife. We examined how these changes are influencing a key zooplankton species,
Calanus finmarchicus
, ...principally found in the North Atlantic but expatriated to the Arctic. Close to the ice-edge in the Fram Strait, we identified areas that, since the 1980s, are increasingly favourable to
C. finmarchicus
. Field-sampling revealed part of the population there to be capable of amassing enough reserves to overwinter. Early developmental stages were also present in early summer, suggesting successful local recruitment. This extension to suitable
C. finmarchicus
habitat is most likely facilitated by the long-term retreat of the ice-edge, allowing phytoplankton to bloom earlier and for longer and through higher temperatures increasing copepod developmental rates. The increased capacity for this species to complete its life-cycle and prosper in the Fram Strait can change community structure, with large consequences to regional food-webs.
Calanoid copepods comprise around 90% of Arctic zooplankton biomass and are fundamental to the ecological and biogeochemical functioning of high-latitude pelagic ecosystems. They accumulate lipid ...reserves during the productive months and represent an energy-rich food source for higher trophic levels. Rapidly changing climate in the Arctic may alter the quantity and composition of the food environment for one of the key copepod species,
Calanus finmarchicus
, with as yet unquantified effects on its production. Here we present rates of feeding and egg production in female
C. finmarchicus
exposed to the range of feeding conditions encountered across the Fram Strait in May/June 2018. Carbon (C) budgets were constructed and used to examine the relationship between feeding and growth (= egg production) in these animals. C-specific ingestion rates (mean ± standard deviation) were highly variable, ranging from 0.015 ± 0.004 to 0.645 ± 0.017 day
-1
(mean = 0.295 ± 0.223 day
-1
), and were positively correlated with food availability. C-specific egg production rates ranged from 0.00 to 0.049 day
-1
(mean = 0.012 ± 0.011) and were not correlated with either food availability or ingestion rate. Calculated gross growth efficiencies (GGE: growth/ingestion) were low, 0.12 ± 0.13 (range = 0.01 to 0.39). The assembled C budgets indicate that the average fraction of ingested food that was surplus to the requirements for egg production, respiration and losses to faecal pellets was 0.17 ± 0.42. We suggest that this excess occurred, at least in part, because many of the incubated females were still undergoing the energetically (C-) expensive process of gonad maturation at the time of sampling, an assertion that is supported by the relatively high C:N (nitrogen) ratios of the incubated females, the typically low egg production rates, and gonad maturation status. Ontogenetic development may thus explain the large variability seen in the relationship between egg production and ingestion. The apparently excessive ingestion rates may additionally indicate that recently moulted females must acquire additional N
via
ingestion to complete the maturation process and begin spawning. Our results highlight the need for improved fundamental understanding of the physiology of high-latitude copepods and its response to environmental change.
Purpose
Alpelisib is newly-available breast cancer agent that targets PIK3 mutations and confers a somewhat unusual adverse event profile. This study focused on older patients (≥ 65 years of age) ...treated outside a clinical trial to gain further experience on how these under-studied patients do with this new agent.
Methods
This descriptive, multi-site study relied on medical record review.
Results
Fifty-one older breast cancer patients were started on alpelisib between May 2019 and September 2020. The median age and number of comorbidities at alpelisib initiation was 71 years and 4, respectively. Thirty-five patients had stopped alpelisib (median time on drug 2.6 months (range: < 1, 9.5 months)) for the following reasons: alpelisib adverse events (
n
= 15), cancer progression (
n
= 13), and other/unknown (
n
= 7). Alpelisib adverse events included hyperglycemia (
n
= 37), diarrhea (
n
= 23), rash (
n
= 19), fatigue (
n
= 12), and mouth sores (
n
= 7); (numbers in parentheses indicate the number of patients with at least one such event). Five patients were hospitalized for hyperglycemia. At the time of report, 14 patients were deceased, and median survival had not been reached.
Conclusion
Older patients might derive further benefit from alpelisib if the adverse event profile of this agent, particularly the hyperglycemia, were able to be better managed.
•Acartia tonsa survival was unaffected by 24 h exposure to Alexandrium catanella at reported bloom concentrations; survival only decreased at exposure levels two orders of magnitude higher.•The ...observed lethal median concentration (LC50) for A. tonsa exposed to A. catenella was 12.45 ng saxitoxin equivalents L − 1.•A. tonsa ingestion rates increased with prey availability for both toxic- (A. catenella) and non-toxic (Rhodomonas sp.) prey.•Ingestion rates were higher when offered A. catenella only, potentially suggesting compensatory feeding.•A. tonsa actively selected non-toxic prey over A. catenella when offered a mixed diet.
Blooms of harmful algae are increasing globally, yet their impacts on copepods, an important link between primary producers and higher trophic levels, remain largely unknown. Algal toxins may have direct, negative effects on the survival of copepods. They may also indirectly affect copepod survival by deterring feeding and thus decreasing the availability of energy and nutritional resources. Here we present a series of short-term (24 h) experiments in which the cosmopolitan marine copepod, Acartia tonsa, was exposed to a range of concentrations of the toxic dinoflagellate, Alexandrium catenella (strain 1119/27, formerly Alexandrium tamarense), with and without the presence of alternative, non-toxic prey (Rhodomonas sp.). We also present the toxin profile concentrations for A. catenella. The survival and feeding of A. tonsa were not affected across the range of concentrations recorded for A. catenella in the field; increased mortality of A. tonsa was only discernible when A. catenella was present at concentrations that exceed their reported environmental concentrations by two orders of magnitude. The observed lethal median concentration (LC50) for A. tonsa exposed to A. catenella was 12.45 ng STX eq L−1. We demonstrate that A. tonsa is capable of simultaneously ingesting both toxic and non-toxic algae, but increases clearance rates towards non-toxic prey as the proportional abundance of toxic A. catenella increases. The ability to actively select non-toxic algae whilst also ingesting toxic algae suggests that consumption of the latter does not cause physical incapacitation and thus does not affect ingestion in A. tonsa. This work shows that short-term exposure to toxic A. catenella is unlikely to elicit major effects on the grazing or survival of A. tonsa. However, more work is needed to understand the longer-term and sub-lethal effects of toxic algae on marine copepods.
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