The role of physico-chemical interactions in the seasonality of toxic dinoflagellate cyst assemblages: The case of the NW Patagonian fjords system

Harmful algal blooms (HABs) are recurrent in the NW Patagonia fjords system and their frequency has increased over the last few decades. Outbreaks of HAB species such as Alexandrium catenella, a causal agent of paralytic shellfish poisoning, and Protoceratium reticulatum, a yessotoxins producer, have raised considerable concern due to their adverse socioeconomic consequences. Monitoring programs have mainly focused on their planktonic stages, but since these species produce benthic resting cysts, the factors influencing cyst distributions are increasingly gaining recognition as potentially important to HAB recurrence in some regions. Still, a holistic understanding of the physico-chemical conditions influencing cyst distribution in this region is lacking, especially as it relates to seasonal changes in drivers of cyst distributions as the characteristics that favor cyst preservation in the sediment may change through the seasons. In this study, we analyzed the physico–chemical properties of the sediment (temperature, pH, redox potential) and measured the bottom dissolved oxygen levels in a “hotspot” area of southern Chile, sampling during the spring and summer as well as the fall and winter, to determine the role these factors may play as modulators of dinoflagellate cyst distribution, and specifically for the cysts of A. catenella and P. reticulatum. A permutational analysis of variance (PERMANOVA) showed the significant effect of sediment redox conditions in explaining the differences in the cyst assemblages between spring-summer and fall-winter periods (seasonality). In a generalized linear model (GLM), sediment redox potential and pH were associated with the highest abundances of A. catenella resting cysts in the spring-summer, however it was sediment temperature that most explained the distribution of A. catenella in the fall-winter. For P. reticulatum, only spring-summer sediment redox potential and temperature explained the variation in cyst abundances. The implications of environmental physico-chemical seasonality for the resting cysts dynamics of both species are discussed.Postprint3,74

Latitudinal Variation in the Toxicity and Sexual Compatibility of Alexandrium catenella Strains from Southern Chile

The bloom-forming toxic dinoflagellate Alexandrium catenella was first detected in southern Chile (39.5–55° S) 50 years ago and is responsible for most of the area’s cases of paralytic shellfish poisoning (PSP). Given the complex life history of A. catenella, which includes benthic sexual cysts, in this study, we examined the potential link between latitude, toxicity, and sexual compatibility. Nine clones isolated from Chilean Patagonia were used in self- and out-crosses in all possible combinations (n = 45). The effect of latitude on toxicity, reproductive success indexes, and cyst production was also determined. Using the toxin profiles for all strains, consisting of C1, C2, GTX4, GTX1, GTX3, and NeoSTX, a latitudinal gradient was determined for their proportions (%) and content per cell (pg cell−1), with the more toxic strains occurring in the north (−40.6° S). Reproductive success also showed a latitudinal tendency and was lower in the north. None of the self-crosses yielded resting cysts. Rather, the production of resting cysts was highest in pairings of clones separated by distances of 1000–1650 km. Our results contribute to a better understanding of PSP outbreaks in the region and demonstrate the importance of resting cysts in fueling new toxic events. They also provide additional evidence that the introduction of strains from neighboring regions is a cause for concern.En prens

The global impact of the COVID-19 pandemic on the management and course of chronic urticaria

Introduction: The COVID-19 pandemic dramatically disrupts health care around the globe. The impact of the pandemic on chronic urticaria (CU) and its management are largely unknown. Aim: To understand how CU patients are affected by the COVID-19 pandemic; how specialists alter CU patient management; and the course of CU in patients with COVID-19. Materials and Methods: Our cross-sectional, international, questionnaire-based, multicenter UCARE COVID-CU study assessed the impact of the pandemic on patient consultations, remote treatment, changes in medications, and clinical consequences. Results: The COVID-19 pandemic severely impairs CU patient care, with less than 50% of the weekly numbers of patients treated as compared to before the pandemic. Reduced patient referrals and clinic hours were the major reasons. Almost half of responding UCARE physicians were involved in COVID-19 patient care, which negatively impacted on the care of urticaria patients. The rate of face-to-face consultations decreased by 62%, from 90% to less than half, whereas the rate of remote consultations increased by more than 600%, from one in 10 to more than two thirds. Cyclosporine and systemic corticosteroids, but not antihistamines or omalizumab, are used less during the pandemic. CU does not affect the course of COVID-19, but COVID-19 results in CU exacerbation in one of three patients, with higher rates in patients with severe COVID-19. Conclusions: The COVID-19 pandemic brings major changes and challenges for CU patients and their physicians. The long-term consequences of these changes, especially the increased use of remote consultations, require careful evaluation. © 2020 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Lt