Eileen J. Cox: her journey with diatoms

Eileen already had a keen interest in science during her school years. She studied Botany at Bristol University from 1967–1970, and it was her University teacher, Professor Frank Round, who inspired her interest in diatoms. During her PhD at Bristol under Frank Round’s supervision (1970–1975) she investigated the biology of tube-dwelling diatoms. At the same time, she worked as Departmental Demonstrator in the Botany Department. She left Bristol University in 1976 and became a Claridge Druce Research Fellow at the University of Oxford (1977–1980). Her investigations focused on the genus Navicula and the ultrastructure of diatom cells more generally. From 1979–1980 Eileen took up a post as lecturer at Pembroke College, University of Oxford. In 1980 Eileen moved to Germany and worked as a Royal Society European Exchange Research Fellow at the Litoralstation, Biologische Anstalt Helgoland. Here her studies focused on living diatoms, in particular the genus Donkinia, and she explored the value of live-cell features as diagnostic characters. From 1982–1985 she worked as a Max Planck research fellow at the Max-Planck-Institute at Plön, and from 1985–1988 as a Fellow of the German Research Foundation at the Max-Planck-Institute of Limnology, River Station, in Schlitz. During these years Eileen’s research on Navicula continued, but she also worked on the genera Placoneis, Parlibellus and Pinnularia, and studied relationships between diatom distributions and the environment. In 1989 Eileen returned to the UK to join the University of Sheffield, first as Research Associate, then as NERC Advanced Research Fellow and Honorary Lecturer, and carried out ecotoxicological studies on zooplankton. In 1992 she joined the Natural History Museum as Research Botanist to continue her research on diatoms. Here Eileen made many important contributions to diatom taxonomy and systematics. She carried out important studies on the naviculoid diatoms, and on live diatoms including her novel research on valve morphogenesis. Eileen has been involved in the organisation of many scientific meetings. In 1987 she organized the first meeting of the German-speaking diatomists in Schlitz, Germany, a meeting that has subsequently developed to include a much larger group of scientists from across Europe and from 2020 onwards will be the European Diatom Meeting. Other meetings she has helped organize include those held by the British Phycological Society, British Diatom Meetings, a NorthWest and Midlands Freshwater Group meeting, the Van Heurck Symposium on Taxonomy, a SETAC Europe meeting, a Society for the History of Natural History Meeting, and several European and International Phycological Congresses. Eileen has taught extensively; hosted 7 post-doctoral fellows and many research visitors to the Natural History Museum; supervised 10 PhD students, 4 M.Sc./M.Phil. students, 1 M.Res. student, and 4 final year B.Sc. students; and examined 9 PhDs and 1 DSc. She is currently a member of six learned societies, has refereed manuscripts for 31 scientific journals, has been invited speaker at 32 scientific meetings, gave 28 invited lectures at universities and research institutes, and presented at 56 national and international conferences. Eileen has given great service to several scientific societies, as council member, secretary or president. These include the British Phycological Society (president 2001–2002), the International Society for Diatom Research (president 2000– 112 Pl. Ecol. Evol. 152 (2), 2019 2002), the Systematics Association, and the International Phycological Society. Since 2007 Eileen has been Head of Postgraduate Studies in the Science Directorate of the Natural History Museum. As part of her role she develops and implements the training programmes of students at NHM, is responsible for strategic planning, and coordinates with research and training partners at universities and research institutions across the UK. Eileen is currently Editor in Chief of Diatom Research, and was previously Associate Editor (2011–2014), she is a board member of Fottea (since 2010), was guest co-editor of the Journal of the North American Benthological Society (Special Issue on Ecology of Springs), guest co-editor of the Journal of Limnology (Special Issue on Spring Biodiversity and Conservation), and Co-Editor-in-Chief of the European Journal of Phycology (2004–2009). Private hobbies include gardening, crafts such as cross stitching and sewing, visiting art museums and travelling, especially river and ocean cruises that have taken Eileen and Elliot recently to Alaska, the Caribbean, Germany, the Czech Republic, France and Portugal. Readers may like to read Eileen’s own description of her journey in diatoms, written for the young diatomists’ blog (available at https://youngisdr.blogspot.com/p/blog-page_12. html or in this volume supplementary information).info:eu-repo/semantics/publishedVersio

Tribute to Eileen J. Cox - Editorial

This issue is dedicated to Dr. Eileen Joan Cox on the occasion of her 70th birthday. Eileen is a very well-known phycologist who has made a major contribution to diatom research, for instance in terms of scientific papers published and species described (all listed in pages 412–414 of this issue) but also in addressing different topics (e.g. taxonomy of particular groups, the ecology of streams and tube dwelling diatoms, life-history and morphogenesis, valve terminology, the chloroplasts of living diatoms, and many others). The photos on the issue’s cover were chosen to reflect some of these aspects of Eileen’s work: Navicula oblonga refers to her work and advocacy of research on living diatoms; Encyonema refers to her earliest work on diatoms that live inside polysaccharide tubes; and Navicula refers to Eileen’s principal taxonomic focus over many years – the diatoms that used to be classified in the catch-all genus Navicula, which have now been split off and placed into many different genera. However, perhaps the most important contribution of a scientist is one that cannot be so easily measured, and that is the positive impact and influence the scientist makes on her/his colleagues. In this respect, Eileen’s contribution has been huge: she has always facilitated collaborations, welcoming students and visitors and putting facilities at their disposal, always taking care of the person as well as the work. She has also volunteered her time and energy generously to scientific societies, editing journals and many other good causes. Not surprisingly we (editors) did not have to make any effort to convince researchers to contribute to this issue. In fact, we faced the opposite problem in having to restrict the number of papers quite severely to keep the issue manageable. We would like to take this opportunity to apologize to all those who would have liked to contribute but have been left out.info:eu-repo/semantics/publishedVersio

The Effects of Acute and Chronic Selective Phosphodiesterase 1 Inhibition on Smooth Muscle Cell-Associated Aging Features

Age-related cardiovascular diseases (CVDs) remain among the leading global causes of death, and vascular smooth muscle cell (VSMC) remodeling plays an essential role in its pathology. Reduced NO-cGMP pathway signaling is a major feature and pathogenic mechanism underlying vasodilator dysfunction. Recently, we identified phosphodiesterase (PDE) 1, an enzyme that hydrolyzes and inactivates the cyclic nucleotides cAMP and cGMP, and thereby provides a potential treatment target for restoring age-related vascular dysfunction due to aging of VSMC. Based on this hypothesis, we here tested the effects of PDE1 inhibition in a model of SMC-specific accelerated aging mice. SMC-KO and their WT littermates received either vehicle or the PDE1 inhibitor lenrispodun for 8 weeks. Vascular function was measured both in vivo (Laser Doppler technique) and ex vivo (organ bath). Moreover, we deployed UV irradiation in cell culture experiments to model accelerated aging in an in vitro situation. SMC-KO mice display a pronounced loss of vasodilator function in the isolated aorta, the cutaneous microvasculature, and mesenteric arteries. Ex vivo, in isolated vascular tissue, we found that PDE1 inhibition with lenrispodun improves vasodilation, while no improvement was observed in isolated aorta taken from mice after chronic treatment in vivo. However, during lenrispodun treatment in vivo, an enhanced microvascular response in association with upregulated cGMP levels was seen. Further, chronic lenrispodun treatment decreased TNF-α and IL-10 plasma levels while the elevated level of IL-6 in SMC-KO mice remained unchanged after treatment. PDE1 and senescence markers, p16 and p21, were increased in both SMC-KO aorta and cultured human VSMC in which DNA was damaged by ultraviolet irradiation. This increase was lowered by chronic lenrispodun. In contrast, lenrispodun increased the level of PDE1A in both situations. In conclusion, we demonstrated that PDE1 inhibition may be therapeutically useful in reversing aspects of age-related VSMC dysfunction by potentiating NO-cGMP signaling, preserving microvascular function, and decreasing senescence. Yet, after chronic treatment, the effects of PDE1 inhibition might be counteracted by the interplay between differential PDE1A and C expression. These results warrant further pharmacodynamic profiling of PDE enzyme regulation during chronic PDE1 inhibitor treatment

Reinvestigation of West African Surirellaceae (Bacillariophyta) described by Woodhead and Tweed from Sierra Leone

Microscope slides containing material from Sierra Leone used by Woodhead and Tweed to describe eight new Surirellaceae taxa in the mid-twentieth century were reinvestigated. Only two taxa were found on the original slides, Surirella approximata Woodhead & Tweed and S. engleri [var. constricta] f. minor Woodhead & Tweed. The valve variability of S. engleri O. Muller includes valves of S. engleri [var. constricta] f. minor which is now regarded as a synonym. As no holotypes were indicated by the authors, types are given here. Comments on S. rudis var. sierra-leonensis Woodhead & Tweed, S. rudis [var. sierra-leonensis] f. constricta Woodhead & Tweed and S. esamangensis Foged are also given. Valves resembling Stenopterobia recta Woodhead & Tweed, Surirella asperrima f. rokuprensis Woodhead & Tweed, S. engleri f. sierra-leonensis Woodhead & Tweed and S. rokuprensis Woodhead & Tweed could not be found on the Woodhead and Tweed original slides

Developing a diatom monitoring network in an urban river-basin: initial assessment and site selection

There is increasing interest in the restoration of urban river systems because they are affected by multiple point- and diffuse-source impairments. In South Wales, these issues are exemplified by the rivers Taff and Ely, which have a well-documented history of pollution. We developed a network of river-monitoring sites to capture as many sources of impairment as possible and to provide an integrated assessment of basin-wide conditions using established, recently revised and new methods to assess ecological status as required by the Water Framework Directive (WFD). Most of the 34 river sites, except those in upstream areas, had moderate or poor ecological status and low species richness. There were significant correlations between the UK Trophic Diatom Index (TDI), phosphate and nitrate concentrations, but the strongest correlation was with sodium concentrations. Sodium also differentiated best between ecological status classes. The UK TDI, Ecological Quality Ratios and the Indice de Polluosensibilité Spécifique (IPS) correlated strongly, but the IPS reflected chemical conditions less well. There were also possible metal impacts including some upstream sites despite apparently good or high ecological status. These data reveal strong capacity in diatoms for reflecting stressors that affect urban river networks. We recommend (i) further assessments including geographically comprehensive and repeated surveys to underpin local decision-making and (ii) further refinement of the tools currently in use for WFD purposes through the development of specific diagnostic indices or multi-metric methods for a comprehensive assessment of complex catchments affected by multiple impairments

Analysis of the type material of Achnanthes minutissima var. macrocephala (Bacillariophyta) and description of two new small capitate Achnanthidium species from Europe and the Himalaya

Background and aims – Two unknown benthic diatom species belonging to the genus Achnanthidium Kütz., and found in French and Nepalese freshwater habitats, were investigated. Both species are here described as new and compared with the original material of Achnanthes minutissima var. macrocephala Hust. [≡ Achnanthidium macrocephalum (Hust.) Round & Bukht.] from Indonesia.Methods – The morphology of three small and capitate Achnanthidium species was investigated using light microscopy (LM) and scanning electron microscopy (SEM).Key results – Achnanthidium coxianum sp. nov. (from the Himalaya) belongs to the group of species with hooked terminal raphe endings, while Achnanthidium peetersianum sp. nov. (from France) has variable terminal raphe endings which are usually slightly bent. Achnanthidium macrocephalum is a much rarer species and illustrations concerning its identity in the literature do not conform to the type studied here.Conclusions – The three species are similar in LM but clearly distinct in SEM. The shape of the areolae and terminal raphe endings separate the species. Achnanthidium macrocephalum has often been misidentified in studies from many areas of the world. It is similar to the new species in valve outline and in its small dimensions

Introduction to the Special Issue

In spite of being one of the main components in the longitudinal zonation of lotic systems, spring habitats have received much less attention than lakes and streams/rivers, and are still widely understudied..

Revision of the Staurosirella leptostauron complex (Staurosiraceae, Bacillariophyta) in Europe with the description of three new species

Background and aims – Small-celled araphid diatoms form an important part of the diatom flora in our rivers and lakes. Although several of these species are frequently reported, their correct taxonomic identity is often obscured due to a lack of good knowledge of the original (type) material. Material and methods – Several historical (nineteenth century) original samples were retrieved from different European and North American diatom collections. The samples have been analysed using light (LM) and scanning electron microscopy (SEM). Key results – Staurosirella crux comb. nov., based on Ehrenberg’s Navicula crux, proved to be the oldest valid name for Staurosirella harrisonii, the latter now being considered a younger synonym. A new European species, S. neorhomboides sp. nov., is described to replace the name S. rhomboides, now considered a younger synonym of S. leptostauron. The North American populations of S. rhomboides and S. martyi differ sufficiently from the type populations and are described as new species: S. moralesii sp. nov. and S. manoyloviana sp. nov. The new combination Staurosirella informis comb. nov. is proposed for a taxon described in 1856 from the French Pyrenees as Odontidium informe. Staurosirella leptostauron turns out to be insufficiently described and is now documented for further use. Conclusion – The analysis of the original (type) material corrected several taxonomic errors and better characterised the morphology of several commonly observed Staurosirella species

Morphological variability within the Achnanthidium minutissimum species complex (Bacillariophyta): comparison between the type material of Achnanthes minutissima and related taxa, and new freshwater Achnanthidium species from Portugal

Two new taxa similar to Achnanthidium minutissimum were common and abundant in samples collected during a survey of benthic diatoms in watercourses from mainland Portugal. They are described here as A. duriense, sp. nov. and A. lusitanicum, sp. nov. In addition, the recently described A. pseudolineare is reported from various localities and its ecology is described in detail. The new Achnanthidium species from Portugal were compared with the type material of morphologically similar taxa: Achnanthidium microcephalum, Achnanthes minutissima, A. minutissima var. cryptocephala, A. minutissima var. inconspicua and A. nana. The analysis of these type material confirmed that Achnanthes minutissima var. cryptocephala should be regarded as a different taxon, and a new combination is proposed, Achnanthidium neocryptocephalum, stat., comb. et nom. nov. Achnanthes minutissima var. inconspicua is now considered as a younger synonym of Achnanthidium lineare. Based on a detailed morphological study of specimens of Achnanthes nana from Scotland, Nepal and Portugal, this taxon is transferred to the genus Achnanthidium as Achnanthidium nanum, comb. nov.This project was supported by Fundação para a Ciência e a Tecnologia—Portugal (PhD grant SFRH/BD/21625/2005), by the Fonds National de la Recherche du Luxembourg (grant AFR, PHD–09–120), by the Public Research Centre - Gabriel Lippmann (Luxembourg) within the framework of the projects FLORALIE and TAXODIA and by the Institute of Earth Sciences (ICT), under contract with FCT (the Portuguese Science and Technology Foundation). We gratefully acknowledge Delphine Collard (Luxembourg Institute of Science and Technology, Environmental Research and Innovation Department, Belvaux, Luxembourg) for technical assistance in preparation of the samples. Dr Jan Krokowski (Scottish Environment Protection Agency, Holytown) is acknowledged for providing the Scottish diatom samples containing Achnanthidium nanum and the respective chemistry measurements. For the loan of type material we thank the Botanical Garden & Museum, Copenhagen (Achnanthes minutissima var. inconspicua Østrup) and Lukas Taxböck, University of Zürich, Institute for Systematic Botany (Achnanthes nana F.Meister)