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The microplastic loads in elvers of the critically endangered European eel Anguilla anguilla, sampled in the lower reaches of three English rivers, were very low (incidence: 3.3%, mean ± s.d.: 0.03 ± 0.18 particles) and did not vary with body length or between rivers. Particles were mostly black, polyolefins, fibres and fragments of size 101-200 μm. Current levels indicate a low contamination pressure locally and, consequently, management efforts might prioritise mitigating the effects of other stressors affecting the species., (© 2023 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

The temporal effects of ethanol preservation on the δ 13 C and δ 15 N values of tissues excised from European eel Anguilla anguilla were assessed. Preservation significantly enriched 13 C values of fin and mucus but not dorsal muscle. The 13 C enrichment occurred in the initial 15 days of preservation and was independent of initial eel mass. Tissue preservation effects on δ 15 N values were negligible. These tissue-specific isotopic shifts should be considered when ethanol-preserved eel samples are used., (© 2023 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

The global COVID-19 pandemic resulted in many jurisdictions implementing orders restricting the movements of people to inhibit virus transmission, with recreational angling often either not permitted or access to fisheries and/or related infrastructure being prevented. Following the lifting of restrictions, initial angler surveys and licence sales suggested increased participation and effort, and altered angler demographics, but with evidence remaining limited. Here, we overcome this evidence gap by identifying temporal changes in angling interest, licence sales, and angling effort in world regions by comparing data in the 'pre-pandemic' (up to and including 2019); 'acute pandemic' (2020) and 'COVID-acclimated' (2021) periods. We then identified how changes can inform the development of more resilient and sustainable recreational fisheries. Interest in angling (measured here as angling-related internet search term volumes) increased substantially in all regions during 2020. Patterns in licence sales revealed marked increases in some countries during 2020 but not in others. Where licence sales increased, this was rarely sustained in 2021; where there were declines, these related to fewer tourist anglers due to movement restrictions. Data from most countries indicated a younger demographic of people who participated in angling in 2020, including in urban areas, but this was not sustained in 2021. These short-lived changes in recreational angling indicate efforts to retain younger anglers could increase overall participation levels, where efforts can target education in appropriate angling practices and create more urban angling opportunities. These efforts would then provide recreational fisheries with greater resilience to cope with future global crises, including facilitating the ability of people to access angling opportunities during periods of high societal stress., Supplementary Information: The online version contains supplementary material available at 10.1007/s11160-023-09784-5., Competing Interests: Conflict of interestThe authors declare no conflict of interest., (© The Author(s) 2023.)

Anthropogenic activities are increasingly threatening aquatic biodiversity, especially anadromous species. Monitoring and conservation measures are thus required to protect, maintain and restore imperilled populations. While many species can be surveyed using traditional capture and visual census techniques, species that use riverine habitats in a less conspicuous manner, such as sea lamprey Petromyzon marinus, can be more challenging to monitor. Sea lamprey larvae (ammocoetes) can spend several years in freshwater burrowed within soft sediments, inhibiting their detection and assessment. Here, we present a qPCR assay based on the detection of environmental DNA (eDNA) to identify the presence of ammocoetes burrowed in the sediment. We present an extensively validated method that ensured both species-specificity of the assay as well as the capacity to detect ammocoetes when abundances are low. Experiments on burrowing activity suggested that most of the DNA released into the sediment occurs during burrowing. Overall, we demonstrate this new molecular-based tool is an efficient and effective complement to traditional monitoring activities targeting larval stages of sea lampreys., (© 2022 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

Ecological studies on the critically endangered European eel Anguilla anguilla often incorporate stable isotope analysis that typically uses dorsal muscle sampled from euthanised eels. To minimise the lethal sampling of imperilled populations, fin tissue and/or epidermal mucus can provide non-lethal alternatives to muscle. The results here indicate that δ 13 C and δ 15 N values of both eel fin and mucus are not significantly different from those of muscle and can be applied directly in comparative SI studies., (© 2022 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

Ticks have relatively complex microbiomes, but only a small proportion of the bacterial symbionts recorded from ticks are vertically transmitted. Moreover, co-cladogenesis between ticks and their symbionts, indicating an intimate relationship over evolutionary history driven by a mutualistic association, is the exception rather than the rule. One of the most widespread tick symbionts is Candidatus Midichloria, which has been detected in all of the major tick genera of medical and veterinary importance. In some species of Ixodes, such as the sheep tick Ixodes ricinus (infected with Candidatus Midichloria mitochondrii), the symbiont is fixed in wild adult female ticks, suggesting an obligate mutualism. However, almost no information is available on genetic variation in Candidatus M. mitochondrii or possible co-cladogenesis with its host across its geographic range. Here, we report the first survey of Candidatus M. mitochondrii in I. ricinus in Great Britain and a multi-locus sequence typing (MLST) analysis of tick and symbiont between British ticks and those collected in continental Europe. We show that while the prevalence of the symbiont in nymphs collected in England is similar to that reported from the continent, a higher prevalence in nymphs and adult males is apparent in Wales. In general, Candidatus M. mitochondrii exhibits very low levels of sequence diversity, although a consistent signal of host-symbiont coevolution was apparent in Scotland. Moreover, the tick MLST scheme revealed that Scottish specimens form a clade that is partially separated from other British ticks, with almost no contribution of continental sequence types in this north-westerly border of the tick's natural range. The low diversity of Candidatus M. mitochondrii, in contrast with previously reported high rates of polymorphism in I. ricinus mitogenomes, suggests that the symbiont may have swept across Europe recently via a horizontal, rather than vertical, transmission route., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Growing to lengths and weights exceeding 1.5 m and 45 kg, the hump-backed mahseer fish of the Western Ghats biodiversity hotspot, India, is an iconic, mega-faunal species that is globally recognized as a premier freshwater game fish. Despite reports of their high extinction risk, conservation approaches are currently constrained by their lack of valid taxonomic identity. Using an integrative approach, incorporating morphology, molecular analysis and historical photographs, this fish can now be revealed to be conspecific with Tor remadevii, a species lacking a common name, that was initially, but poorly, described in 2007 from the River Pambar, a tributary of the River Cauvery in Kerala. Currently known to be endemic and restricted to the River Cauvery basin in the Western Ghats, T. remadevii is distinguished from congeners by its prominent hump originating above the pre-opercle and extending to the origin of the dorsal fin, a well-developed mandible resulting in a terminal or slightly superior mouth position, and the dorsal orientation of the eyes. While body colouration varies (silver, bronze, greenish) and is not considered a reliable diagnostic character, orange coloration of the caudal fin (sometimes extending to all fins) is considered a consistent characteristic. Having been first brought to the attention of the scientific community in 1849, and the recreational angling (game fishing) community in 1873, it has taken over 150 years to finally provide this iconic fish with a valid scientific name. This taxonomic clarity should now assist development and delivery of urgent conservation actions commensurate with their extinction risk., Competing Interests: The authors declare that no competing interests exist. Views and opinions expressed by the authors are their own and do not in any way represent those of the organization(s) they represent.

Much of the developing world and areas of the developed world suffer water vulnerability. Engineering solutions enable technically efficient extraction and diversion of water towards areas of demand but, without rebalancing resource regeneration, can generate multiple adverse ecological and human consequences. The Banas River, Rajasthan (India), has been extensively developed for water diversion, particularly from the Bisalpur Dam from which water is appropriated by powerful urban constituencies dispossessing local people. Coincidentally, abandonment of traditional management, including groundwater recharge practices, is leading to increasingly receding and contaminated groundwater. This creates linked vulnerabilities for rural communities, irrigation schemes, urban users, dependent ecosystems and the multiple ecosystem services that they provide, compounded by climate change and population growth. This paper addresses vulnerabilities created by fragmented policy measures between rural development, urban and irrigation water supply and downstream consequences for people and wildlife. Perpetuating narrowly technocentric approaches to resource exploitation is likely only to compound emerging problems. Alternatively, restoration or innovation of groundwater recharge practices, particularly in the upper catchment, can represent a proven, ecosystem-based approach to resource regeneration with linked beneficial socio-ecological benefits. Hybridising an ecosystem-based approach with engineered methods can simultaneously increase the security of rural livelihoods, piped urban and irrigation supplies, and the vitality of river ecosystems and their services to beneficiaries. A renewed policy focus on local-scale water recharge practices balancing water extraction technologies is consistent with emerging Rajasthani policies, particularly Jal Swavlamban Abhiyan ('water self-reliance mission'). Policy reform emphasising recharge can contribute to water security and yield socio-economic outcomes through a systemic understanding of how the water system functions, and by connecting goals and budgets across multiple, currently fragmented policy areas. The underpinning principles of this necessary paradigm shift are proven and have wider geographic relevance, though context-specific research is required to underpin robust policy and practical implementation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Diets rich in n-3 polyunsaturated fatty acids (PUFAs) are associated with suppression of cell-mediated immune responses, but the mechanisms are unclear. We hypothesized that n-3 PUFAs can inhibit the function of human antigen-presenting cells. A prerequisite for this role of blood monocytes is the cell surface expression of major histocompatibility complex (MHC) class II molecules [human leukocyte antigen (HLA)-DR, -DP, and -DQ], aided by the presence of intercellular adhesion molecule-1 (ICAM-1) and leukocyte function associated antigens 1 and 3. We showed previously that the n-3 PUFA eicosapentaenoic acid (EPA) inhibits the expression of HLA-DR on unstimulated human monocytes in vitro, but that docosahexaenoic acid (DHA) enhances its expression. However, both n-3 PUFAs suppress the expression of HLA-DR, HLA-DP, and ICAM-1 on interferon-gamma-activated monocytes. We also established that dietary fish-oil supplementation can inhibit the expression of these surface molecules on circulating human monocytes. We subsequently showed that when EPA and DHA were combined in the same ratio as is commonly found in fish-oil-supplement capsules (3:2), there was no significant effect in vitro on the expression of HLA-DR on unstimulated monocytes, but the expression on activated monocytes remained significantly inhibited. In the same in vitro system, the ability of activated monocytes to present antigen to autologous lymphocytes was significantly reduced after culture with the combined n-3 PUFAs. These findings provide one potential mechanism for the beneficial effect of fish oil in the treatment of rheumatoid arthritis, a disorder associated with elevated expression of MHC class II and adhesion molecules on monocytes present within affected joints.

Fish oil has been shown to reduce the induction of colorectal cancer in animal models by a mechanism which may involve suppression of mitosis, increased apoptosis, or both. We used the human colonic adenocarcinoma cell line HT29 to explore the effects of the long-chain n-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) on cell proliferation and death in vitro. Cells were cultured in media containing EPA at 5, 10, and 15 microg/mL. Cell number and thymidine incorporation were used to quantify proliferation, and cell cycle effects were studied using flow cytometry. Gel electrophoresis, annexin-V binding, and morphological criteria were used to characterize apoptosis. Adherent cells and freely floating detached cells were treated as two distinct populations. In the presence of EPA at 10 and 15 microg/mL there was a marked reduction in the growth rate of adherent HT29 colonies, owing to an increased detachment of adherent cells. After treatment with 10 or 15 microg/mL EPA the proportion of adherent cells in S-phase increased, indicating either a block in late S-phase or early G2. Floating cells showed evidence of extensive DNA cleavage, but the proportion of floating cells with sub GO DNA content declined on treatment with 10 or 15 microg/mL EPA even though the number of floating cells increased. We conclude that EPA does not inhibit mitosis of adherent cells, but increases the rate at which they become detached from the substrate, probably at an early stage in the initiation of apoptosis. This mechanism may be analogous to "anoikis," or induction of apoptosis in response to loss of cell contact, and may contribute to the anticarcinogenic effects of fish oil in vivo.

A proprietary fluorogenic marker for cell viability (Chemchrome) was investigated for the detection of bacteria using flow cytometry. This marker was used in combination with fluorescently labelled monoclonal antibodies (against Salmonella typhimurium). Owing to the former's broad band emission spectrum, it was necessary to use the novel dye RED613 for the antibodies. This combined protocol, being sensitive only to the live Salm. typhimurium cells, reduced errors due to intrinsic fluorescence and non-specific binding. Detection of the order of 100 cells ml-1 was achieved in 30 min. This level was achieved even in the presence of large numbers of non-target or dead organisms.

N-3 polyunsaturated fatty acid (PUFA)-rich diets are associated with suppression of cell-mediated immune responses, but the mechanisms are unclear. Specific immune responses are initiated by antigen-presenting cells (APC). We have previously shown in vitro that the n-3 PUFA, eicosapentaenoic acid (EPA), inhibits the expression of HLA-DR, an MHC class II molecule required for normal APC function on human blood monocytes. In contrast, docosahexaenoic acid (DHA) enhanced the expression of this molecule on unstimulated monocytes, but both n-3 PUFA suppressed its expression on interferon-gamma (IFN-gamma)-activated monocytes. In the present study we show that when EPA and DHA were combined at the same ratio as is commonly found in fish oil supplement capsules (3:2) there was no significant effect in vitro on the expression of HLA-DR on unstimulated monocytes, but the expression on IFN-gamma-activated monocytes remained significantly inhibited. In the same in vitro system a significant reduction in the ability of IFN-gamma-activated monocytes to present tetanus toxoid antigen to autologous lymphocytes was observed following culture with the combined n-3 PUFA. These findings support previous animal studies which suggest that n-3 PUFA can inhibit the antigen-presenting function of mononuclear phagocytes.

Although there is strong epidemiologic evidence that diets rich in carotenoids such as beta-carotene are associated with a reduced incidence of cancer, the cellular mechanisms underlying this phenomenon remain unknown. This article describes the effect of dietary beta-carotene supplementation on both the expression of functionally associated surface molecules on human monocytes and on the secretion of the cytokine tumor necrosis factor-alpha (TNF-alpha) by monocytes, all of which are involved in the initiation and regulation of immune responses involved in tumor surveillance. A double-blind, placebo-controlled, crossover study was undertaken in which 25 healthy, adult male nonsmokers were randomly assigned to receive beta-carotene (15 mg daily) or placebo for 26 days, followed by the alternative treatment for a further 26 days. The expression of functionally related monocyte surface molecules was quantified by flow cytometry, and ex vivo secretion of TNF-alpha was quantified by an enzyme-linked immunosorbent assay, before and after each treatment period. After dietary supplementation there were significant increases in plasma levels of beta-carotene and in the percentages of monocytes expressing the major histocompatibility complex class II molecule HLA-DR and the adhesion molecules intercellular adhesion molecule-1 and leukocyte function-associated antigen-3. In addition, the ex vivo TNF-alpha secretion by blood monocytes was significantly increased after supplementation. These findings suggest that moderate increases in the dietary intake of beta-carotene can enhance cell-mediated immune responses within a relatively short period of time, providing a potential mechanism for the anticarcinogenic properties attributed to beta-carotene.

Diets rich in (n-3) polyunsaturated fatty acids (PUFA) are associated with suppression of the immune system, but the mechanisms are unclear. Specific immune responses are initiated by antigen-presenting cells. This study examines the in vitro effect of the (n-3) PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the expression of cell surface molecules required for normal antigen-presenting cell function on human blood monocytes. Monocytes were incubated with or without EPA or DHA for 48 h at 37 degrees C. Following incubation, expression of major histocompatibility complex (MHC) class II molecules (HLA-DR, -DP and -DQ) and adhesion molecules [intercellular adhesion molecule-1 (ICAM-1) and leucocyte function associated antigen-1] was quantified by flow cytometry. In the presence of EPA alone there was a significantly lower median intensity of expression of HLA-DR and ICAM-1 relative to incubations without EPA. In contrast, significantly greater median intensities of expression of HLA-DR and -DP were observed following incubation with DHA. In parallel experiments, where monocytes were simultaneously activated by the addition of interferon-gamma to the cultures, median expression intensities of HLA-DR, -DP and ICAM-1 were significantly lower in the presence of either EPA or DHA compared with incubations without the (n-3) PUFA. These findings support previous animal studies that suggest that (n-3) PUFA can influence immune reactivity by modulating antigen-presenting cell function.

Flow cytometry, combined with fluorescently labelled monoclonal antibodies, offers advantages of speed and sensitivity for the detection of specific pathogenic bacteria in foods. We investigated the detection of Salmonella typhimurium in eggs and milk. Using a sample clearing procedure, we determined that the detection limit was on the order of 10(3) cells per ml after a total analysis time of 40 min. After 6 h of nonselective enrichment, the detection limits were 10 cells per ml for milk and 1 cell per ml for eggs, even in the presence of a 10,000-fold excess of Escherichia coli cells.

The use of fluorescently-labelled monoclonal antibodies, with detection by multi-parameter flow cytometry, was investigated for the rapid detection of salmonellas in pure cultures. Accurate detection of specific Salmonella serotypes was demonstrated down to levels of below 10(4) cells ml-1 (within 30 min) and 1 cell ml-1 (after 6 h non-selective pre-enrichment). This level of sensitivity was attained even in the presence of high levels of other bacterial species that would otherwise have interfered with the results. With combinations of different antibodies, each with a unique fluorescent label, simultaneous analysis for two species was possible.

Multi-parameter flow cytometry was investigated for the rapid detection of specific serotypes of salmonellas (S. typhimurium and S. montevideo) labelled with fluorescent monoclonal antibodies, both in pure culture and in a typical food matrix (full-fat milk). In all cases, the method was accurate to levels of below 10(4) target cells per ml for a total assay time of about 30 min. After 6 h non-selective enrichment in the presence of a 10,000-fold excess of competing micro-organisms (Escherichia coli) the corresponding detection limit was about 20 cells ml-1. These results suggest that flow cytometry has significant potential for the detection of pathogenic micro-organisms in the food industry.

Flow cytometry was investigated as a rapid detection and counting method for bacteria in pure cultures. A simple two-parameter detection scheme was employed: particle size was measured by forward angle light scatter and nucleic acid content by fluorescence of the DNA/RNA-binding dye ethidium bromide. The technique gave results that correlated exceptionally well with conventional plate counting for four species of bacteria, and concentrations in the range 10(2) to 10(7) cfu/ml. Cytometric counts were obtained in a few minutes, as compared with 2 d required for the plate counts. Under ideal conditions, each bacterial species examined exhibited a characteristic 'signature' on the cytometer, which could be explained by its known properties and morphology.

The motion of the amphibian eardrum under free-field acoustic stimulation was investigated using time-averaged holography. We show that the amplitude is linearly related to sound pressure up to +/- 1000 nm. The frequency response of the eardrum shows broad resonance characteristics with a main peak between 1200-2200 Hz. The velocity of the tympanic membrane's motion at its resonance frequency matches the acoustic velocity of air particles. The resonance characteristics of the eardrum are also revealed by white noise stimulation. The power spectrum obtained by Fourier transformation of the autocorrelation of the response to noise resembles closely that obtained by holography.

Flow cytometry is a technique for analysing and separating populations of cells (and subcellular components). The cells are generally stained with fluorescent markers (eg, fluorescent antibodies or DNA-binding dyes). Each cell is analysed individually, at high speed. Thus, assays may be performed on small samples (less than 10,000 cells). A subpopulation of interest can be separated from the remainder of the cells to a high degree of purity (up to 99 per cent). The application of flow cytometry to veterinary science is increasing and is discussed here.

The acoustically induced motion of the eardrum of the frog was measured by an incoherent optical technique. When free-field sound stimulation was used, the eardrum vibration had a band-pass characteristic with maximum amplitude at 1-2.5 kHz. However, when the sound was presented in a closed-field acoustic coupler the response was low-pass (cut-off frequency about 2.5 kHz). We demonstrate that the motion is the result of the mechanical properties of the eardrum and the sound pressure acting upon it. The net pressure is due to a combination of sound incident directly on the front of the drum and of sound conducted to the rear via internal (resonant) pathways. The frog ear therefore acts as a pressure-gradient receiver at low frequency and a pressure receiver at high frequency. A model is proposed and analysed in terms of its electrical analogue. This model accounts for both our own experimental observations and those of previous studies.

New applications which are areas of potential growth for the science of flow microfluorimetry (FMF) and represent a major shift in direction away from its principal current use by cellular immunologists were highlighted at a recent meeting. Its intention was to inform flow microfluorimetrists of current trends in machine and dye technology and new applications in particular chromosome analysis and the analysis of cells isolated from solid tissue., (Copyright © 1985. Published by Elsevier B.V.)

The application of flow cytometric or microfluorimetric techniques to the biomedical sciences is a major growth area. Flow microfluorimetry is the science of analyzing and separating populations of cells (and their sub-cellular components) using fluorescent markers (usually fluorescent antibodies or fluorescent DNA-binding dyes). Each cell is analysed individually allowing assays to be performed on small samples (less than 10,000 cells). Interesting cells can be sorted out to a high degree of purity (up to 99%). Flow microfluorimetric analysis enjoys multidisciplinary use, ranging from cell biology, microbiology and immunology to cell cycle analysis and "flow karyotyping" of cells. Examples taken from both clinical and research settings are discussed.

The frog ear can be modelled as two coupled eardrums with an additional sound pathway through the mouth cavity. In a previous version of this model, with realistic parameters, we were able to account very well for empirical measurements of the eardrum vibration under free- and closed-field acoustic conditions. This earlier model does not, however, adequately predict the directional characteristics of the frog ear as determined empirically. In this paper we present a modified model which will account for the directionality together with the free- and closed-field frequency responses, and which is also consistent with anatomical considerations.