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Valeria Lencioni - One of the best experts on this subject based on the ideXlab platform.
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A long noncoding RNA acts as a post-transcriptional regulator of heat shock protein (HSP70) synthesis in the cold hardy Diamesa tonsa under heat shock.
PloS one, 2020Co-Authors: Paola Bernabò, Gabriella Viero, Valeria LencioniAbstract:Cold stenothermal insects living in glacier-fed streams are stressed by temperature variations resulting from glacial retreat during global warming. The molecular aspects of insect response to environmental stresses remain largely unexplored. The aim of this study was to expand our knowledge of how a cold stenothermal organism controls gene expression at the transcriptional, translational, and protein level under warming conditions. Using the chironomid Diamesa tonsa as target species and a combination of RACE, qPCR, polysomal profiling, western blotting, and bioinformatics techniques, we discovered a new molecular pathway leading to previously overlooked adaptive strategies to stress. We obtained and characterized the complete cDNA sequences of three heat shock inducible 70 (hsp70) and two members of heat-shock cognate 70 (hsc70). Strikingly, we showed that a novel pseudo-hsp70 gene encoding a putative long noncoding RNA (lncRNA) which is transcribed during thermal stress, acting as a ribosome sponge to provide post-transcriptional control of HSP70 protein levels. The expression of the pseudo-hsp70 gene and its function suggest the existence of a new and unexpected mechanism to cope with thermal stress: lowering the pace of protein production to save energy and optimize resources for recovery.
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Multi-level effects of emerging contaminants on macroinvertebrates in Alpine streams: From DNA to the ecosystem
Ecological Indicators, 2020Co-Authors: Valeria Lencioni, Francesco Bellamoli, Francesca PaoliAbstract:Abstract The aim of this study was to highlight the effects of water treatment plant (WTP) effluents on the macroinvertebrates of the Noce River (Italian Alps), from its headwaters (at TP_Up at 1792 m a.s.l. and TP_Dw at 1790 m a.s.l., which were 70 m upstream and 50 m downstream of the Tonal Pass WTP, respectively) to lowland reaches (at ML at 221 m a.s.l., 13 km downstream of one WTP and two reservoirs). The effects of five emerging contaminants (ECs; ibuprofen = IBU, furosemide = FUR, trimethoprim = TMP, triclocarban = TCC, and sucralose = SUCR) present in the effluents were evaluated seasonally (winter/summer) at multiple levels of biological organisation—from effects on the DNA (genotoxicity) to the organism (acute toxicity), community (alpha-diversity) and ecosystem (with environmental quality assessed using the STAR_ICMi and IBE indices). Eight insect species were selected for assessment: Baetis alpinus, Baetis rhodani, Diamesa cinerella, Dictyogenus alpinus, Perlodes intricatus, PseudoDiamesa branickii, Rhyacophila occidentalis, and Rhyacophila tristis. Responses to the five ECs were evaluated specific to species and sites. Among the tested ECs, IBU was the most harmful. While SUCR was less toxic, it was significantly genotoxic. According to the acute toxicity (96 h) and genotoxicity (Comet assay at sub-lethal concentrations) tests, D. cinerella exhibited the highest tolerance and B. alpinus the highest sensitivity to all tested ECs. Populations living at the TP_Dw, the site most contaminated by ECs in winter, accumulated the highest basal DNA damage but were more tolerant to chemical stressors. The negative effect of WTPs on biodiversity was highlighted with reduced alpha-diversity, which was the lowest at TP_Dw during winter when tourist influx was the highest and river discharge was the lowest. The general stress conditions identified by changes to species composition and both toxicity tests were not detected by the STAR_ICMi and IBE indices, with the ecological status reported as good/excellent at all sites during all seasons. This emphasises how these indices, unlike biomarkers, are not good early warning indicators of the effects of trace ECs in running waters. The Comet assay has high potential for identifying stress in wild populations, even when exposed to environmental concentrations of ECs that are far lower than those required to cause acute toxicity.
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Structural and functional changes in the macroinvertebrate community in Alpine stream networks fed by shrinking glaciers
Fundamental and Applied Limnology Archiv für Hydrobiologie, 2020Co-Authors: Valeria Lencioni, Alessandra Franceschini, Francesca Paoli, Daniele DebiasiAbstract:The status of glaciers is alarming globally with still unknown effects on freshwater ecosystems. Thegeneral aim of this study was to investigate the structural and functional changes in the macroinvertebrate communityin stream networks fed by shrinking glaciers in relation to environmental variables. Feeding glaciers haddifferent surface areas and retreating rates. We selected 10 study sites in the Italian Alps, spanning five kryal, twoglacio-rhithral, two krenal and one proglacial pond, sampled twice in summer 2018. Eight of these sites weresampled previously between 1996 and 2014. In all, in 2018, > 15,000 individuals (73 taxa) were collected, of which82 % were chironomids (Diptera Chironomidae) (33 taxa). Diamesa zernyi gr. (Chironomidae Diamesinae) wasthe most frequent and abundant taxon, followed by Oligochaeta and Chironomidae Orthocladiinae. Taxonomical(Shannon index) and functional (based on functional feeding groups) diversity both increased with decreasingglacial influence (estimated as glacial index, GI, based on distance from the glacier snout of each site and glacierarea), from kryal to glacio-rhithral and krenal habitats. Taxa distribution was explained mainly by GI, maximumwater temperature, substrate stability, silica, epilithic chlorophyll-a, and benthic particulate organic matter. Thesame variables explained temporal differences in the community structure for the eight sites re-sampled in the lasttwo decades. Among the taxa best associated with high GI was the chironomid Diamesa steinboecki, that in 2018was exclusive of the kryal sites with GCC (% glacier cover in the catchment, expressed in a range from 0 %–100 %)> 50 % and maximum temperature < 5 °C. This species was absent only in the kryal site C0 (GCC = 33 %), whereit was dominant in 1996 –1997. This site was still fed by ice melt in 2018, but resembled a glacio-rhithral site inhabitat features (e.g. maximum temperature > 6 °C) and biota (e.g. % Diamesa spp. < 30 %). In C0, it was evidentthat in the last 22 years, the macroinvertebrate community changed remarkably. This change was due to upstreammigration of generalist insect species to sites once exclusive for kryal species with consequent changes in food webstructure and loss of strictly kryal species, first D. steinboecki that we propose as the “flagship” species of the kryalin the Alps. The site C0 represents a “tipping point”, showing us the effects of climate change on alpine biodiversityin a relatively short period; unfortunately, there are many such sites in the Italian Alps.
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A long noncoding RNA acts as a post-transcriptional regulator of heat shock protein 70 kDa synthesis in the cold hardy Diamesa tonsa under heat shock
2019Co-Authors: Valeria Lencioni, Paola Bernabò, Gabriella VieroAbstract:Cold stenothermal insects living in glacier-fed streams are stressed by temperature variations resulting from glacial retreat during global warming. The molecular aspects of insect response to environmental stresses remain largely unexplored. The aim of this study was to expand our knowledge of how a cold stenothermal organism controls gene expression at the transcriptional, translational, and protein level under warming conditions. Using the chironomid Diamesa tonsa as target species and a combination of RACE, qPCR, polysomal profiling, western blotting, and bioinformatics techniques, we discovered a new molecular pathway leading to previously overlooked adaptive strategies to stress. We obtained and characterized the complete cDNA sequences of three heat shock inducible 70 ( hsp70 ) and two members of heat-shock cognate 70 ( hsc70 ). Strikingly, we showed that a novel pseudo-hsp70 gene encoding a putative long noncoding RNA (lncRNA) which is transcribed during thermal stress, acting as a ribosome sponge to provide post-transcriptional control of HSP70 protein levels. The expression of the pseudo-hsp70 gene and its function suggest the existence of a new and unexpected mechanism to cope with thermal stress: lowering the pace of protein production to save energy and optimize resources for recovery.
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Behavioural and biochemical alterations by chlorpyrifos in aquatic insects: an emerging environmental concern for pristine Alpine habitats
Environmental Science and Pollution Research, 2019Co-Authors: Valeria Di Nica, Valeria Lencioni, Ana Belén Muñiz González, Sara VillaAbstract:This study aimed to assess how different concentrations of the insecticide chlorpyrifos (1.1, 5.24, 11, 52.4, 110, 262, 524 and 1100 ng L^−1) affect the swimming behaviour of Diamesa zernyi larvae following exposure. A video tracking system was employed to analyse two swimming traits (total distance moved and average speed) of the larvae simultaneously after 3 days of exposure to the pesticide at 2 °C. The behavioural results were also interpreted according to biochemical responses to oxidative stress (OS) induced by chlorpyrifos, based on malondialdehyde (MDA) and protein carbonyl (PCC) content. Both distance and speed significantly decreased after 72 h of exposure to chlorpyrifos concentrations of ≥ 110 ng L^−1, under which significant OS was detected as lipid peroxidation (level of MDA) and protein carbonylation (level of carbonyl). Analysis of altered swimming behaviour, along with MDA and carbonyl content, indicated that ≥ 110 ng L^−1 contamination levels of the insecticide cause the organism to reallocate energy normally used for locomotor activity to repair cell damage, which might explain the strong impairment to locomotor performance. Locomotor performance is an ecologically relevant trait for elucidating the population dynamics of key species, with disturbance to this trait having long-term negative impacts on population and community structure. Therefore, chlorpyrifos insecticides represent a serious ecological risk for mountain aquatic species based on the detrimental effects observed in the current study, as the tested concentrations were those at which the insecticide is found in many Alpine rivers of Italy.
Bruno Rossaro - One of the best experts on this subject based on the ideXlab platform.
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The species of the genus Diamesa (Diptera, Chironomidae) known to occur in Italian Alps and Apennines.
Zootaxa, 2016Co-Authors: Matteo Montagna, Sandra Urbanelli, Bruno RossaroAbstract:Some rare species from Italian Alps, belonging to the genus Diamesa Meigen, 1835 (Diptera, Chironomidae) are here redescribed as adult males, because only old, incomplete descriptions are available for these taxa. Terminology of male genitalia is reviewed, diagnostic features are illustrated in detail, and notes on biology and geographical distribution of the examined species are provided. An identification key to the known adult males is presented.
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integrated taxonomy and dna barcoding of alpine midges diptera chironomidae
PLOS ONE, 2016Co-Authors: Matteo Montagna, Valeria Lencioni, Valeria Mereghetti, Bruno RossaroAbstract:Rapid and efficient DNA-based tools are recommended for the evaluation of the insect biodiversity of high-altitude streams. In the present study, focused principally on larvae of the genus Diamesa Meigen 1835 (Diptera: Chironomidae), the congruence between morphological/molecular delimitation of species as well as performances in taxonomic assignments were evaluated. A fragment of the mitochondrial cox1 gene was obtained from 112 larvae, pupae and adults (Diamesinae, Orthocladiinae and Tanypodinae) that were collected in different mountain regions of the Alps and Apennines. On the basis of morphological characters 102 specimens were attributed to 16 species, and the remaining ten specimens were identified to the genus level. Molecular species delimitation was performed using: i) distance-based Automatic Barcode Gap Discovery (ABGD), with no a priori assumptions on species identification; and ii) coalescent tree-based approaches as the Generalized Mixed Yule Coalescent model, its Bayesian implementation and Bayesian Poisson Tree Processes. The ABGD analysis, estimating an optimal intra/interspecific nucleotide distance threshold of 0.7%-1.4%, identified 23 putative species; the tree-based approaches, identified between 25–26 entities, provided nearly identical results. All species belonging to zernyi, steinboecki, latitarsis, bertrami, dampfi and incallida groups, as well as outgroup species, are recovered as separate entities, perfectly matching the identified morphospecies. In contrast, within the cinerella group, cases of discrepancy arose: i) the two morphologically separate species D. cinerella and D. tonsa are neither monophyletic nor diagnosable exhibiting low values of between-taxa nucleotide mean divergence (0.94%); ii) few cases of larvae morphological misidentification were observed. Head capsule color is confirmed to be a valid character able to discriminate larvae of D. zernyi, D. tonsa and D. cinerella, but it is here better defined as a color gradient between the setae submenti and genal setae. DNA barcodes performances were high: average accuracy was ~89% and precision of ~99%. On the basis of the present data, we can thus conclude that molecular identification represents a promising tool that could be effectively adopted in evaluating biodiversity of high-altitude streams.
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Environmental traits affect chironomid communities in glacial areas of the Southern Alps: evidence from a long-lasting case study
Insect Conservation and Diversity, 2016Co-Authors: Bruno Rossaro, Matteo Montagna, Valeria LencioniAbstract:A collection of approximately 100 000 chironomids (Diptera; Chironomidae) inhabiting glacial areas of the Southern Alps that were collected over a period of approximately four decades from 1977 to 2014 were analysed to evaluate the impact of environmental traits on the distribution of chironomid species. Although the list of species has not substantially changed over time, some rare species captured in the 1970s have not been collected in recent years, while other species have only been collected recently. The recovered correlation between altitude of the sampling sites and the date of collection since the first sampling event emphasises the need, in recent years, to sample at higher altitudes to collect species living near the glacier snout. This result confirms the impact of glacial retreat on chironomid communities. Temporal trends in diversity were not emphasised throughout the collecting period. A canonical correspondence analysis (CCA) showed that the influence of glaciers is the ecological trait that is the most robust predictor of the spatial distribution of species. This trait was highly correlated with the first CCA axis. Diamesa steinboecki, Diamesa latitarsis, Diamesa modesta, Diamesa goetghebueri and Diamesa laticauda are species that are known to be restricted to glacial habitats and were correlated with the first axis. The second CCA axis separated Western from Central-Eastern glaciers, with Diamesa cinerella prevailing in the former. The threshold indicator taxa analysis, which detects changes in the distribution of taxa along an environmental gradient, confirmed the results of CCA in selecting Diamesa species with the strongest preference for glacial habitats.
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A key to larvae of Diamesa Meigen, 1835 (Diptera, Chironomidae), well known as adult males and pupae from Alps (Europe)
Journal of Entomological and Acarological Research, 2015Co-Authors: Bruno Rossaro, V. LencioniAbstract:A key to species belonging to the genus Diamesa Meigen, 1835 (Diptera, Chironomidae) well known as adult males and pupal exuviae from European Alps, is presented; the characters useful in species identification are pictured. The key considers both qualitative and quantitative characters. Thirteen morpho-species are distinguished, probably more species have a very similar larva and can be separated only in the adult or pupal stage. The most discriminant quantitative characters are the length and thickness of anal setae, among qualitative characters the most discriminant ones are the head capsule colour and the split of setae anteriores of labrum. The shape of mental and mandibular teeth are good taxonomic characters, but can be rarely used because teeth are often worn out in samples collected in the field. Quantitative characters show variability within each species, differing according to the sampled site and season, and must be used with caution. The following species groups can be easily separated in the larval stage: i) dampfi , including D. dampfi and D. permacra ; ii) latitarsis including D. modesta and D. latitarsis ; iii) zernyi including D. zernyi and D. vaillanti . D. starmachi , D. steinboecki , D. goetghebueri , D. bertrami , D. aberrata , D. incallida , D. cinerella , D. tonsa and D. insignipes can be separated from all the other known species in larval stage, but some of them, D. cinerella and D. insignipes for example, have a very similar larva, so are better separated on the basis of their distribution and collection of adults and pupae are strongly recommended to support identifications. A new character bound to head capsule colour is proposed to separate D. insignipes , D. cinerella , D. tonsa and D. zernyi.
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A KEY TO LARVAE OF SPECIES BELONGING TO THE GENUS Diamesa FROM ALPS AND APENNINES (ITALY)
EUROPEAN JOURNAL OF ENVIRONMENTAL SCIENCES, 2015Co-Authors: Bruno Rossaro, Valeria LencioniAbstract:A key to species belonging to the genus Diamesa Meigen, 1835 (Diptera, Chironomidae) from the Alps and Apennines (Italy) is presented using characters observable in the fourth-instar larva. The larvae are separated on the basis of qualitative and quantitative characters. At present fifteen species from the Italian Alps are described in all three life stages, but only twelve species groups can be separated as larvae. The separation is based on the length and thickness of anal setae, antennal ratio, head capsule color and few other characters of the labrum and mentum. The shape of mental and mandibular teeth is still a valid taxonomic character, but unfortunately these characters can be rarely used because teeth are often excessively worn in samples collected in the field. Quantitative characters show variability within each species, differing according to the duration of larval development and must be used with caution. The species groups which can be separated in the larval stage are: the dampfi group, which includes D. dampfi and D. permacra, the latitarsis group including D. modesta and D. latitarsis, the zernyi group including D. zernyi and D. vaillanti. The species within each of these groups at present cannot be separated. D. starmachi, D. steinboecki, D. goetghebueri, D. bertrami, D. aberrata, D. incallida, D. cinerella, D. tonsa and D. insignipes can be separated from all the other known species in larval stage.
Leonard C. Ferrington - One of the best experts on this subject based on the ideXlab platform.
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Emergence Dynamics of Diamesa cheimatophila Hansen (Diptera: Chironomidae: Diamesinae)
EUROPEAN JOURNAL OF ENVIRONMENTAL SCIENCES, 2015Co-Authors: Leonard C. Ferrington, Edwin C. MastellerAbstract:Emergence of Diamesa cheimatophila was determined for a five year period (1981–1986) using a permanently operated walk-in emergence trap over a spring-fed tributary of Fourmile Creek in Erie, northeast Pennsylvania. Annual emergence started in September/October, continued sporadically through winter until April/May and occurred over a span of 185–236 days. Averaged over the five years of our study, > 80% of annual emergence occurred during winter when long-term average air temperatures are less than 10 degrees C. Emergence of D. cheimatophila shows patterns similar to emergence of D. mendotae Muttkowski at groundwater-influenced stream sites in Minnesota, where it is known to produce 2–3 cohorts per year during winter. Well-defined peaks in winter emergence of D. cheimatophila indicates at least two, but possibly three or four cohorts emerging per winter. The year-to-year variability in emergence of D. cheimatophila strongly suggests this species also conforms to the Labile Life Cycle Hypothesis proposed for D. mendotae, (but refined in this paper) with the actual number of cohorts produced per winter depending on the onset and duration of cold air temperatures.
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Factors affecting decomposition rates of chironomid (Diptera) pupal exuviae
CHIRONOMUS Journal of Chironomidae Research, 2014Co-Authors: Rathi G. Kavanaugh, Alexander T. Egan, Leonard C. FerringtonAbstract:Collections of floating chironomid pupal exuviae are used to monitor water quality and assess ecological conditions. Factors controlling exuviae sinking rates are not well known, although they should have an effect on conclusions that can be drawn from collections. The current study was conducted to determine the rate of sinking under controlled laboratory conditions using water from three streams with different nutrient levels. Sinking rates ranged from less than a day to seven days, depending on microbial activity, nutrient concentrations, temperature and turbulence. Results also varied by genus, with pupal exuviae of Chironomus riparius , Diamesa nivoriunda , Orthocladius ( Euorthocladius ) thienemanni and Eukiefferiella sp. used in experiments. Four species of bacteria and eight genera of fungi colonized and metabolized exuviae, with bacteria dominant early and fungi dominant later in the decomposition process. Decomposition was faster in lightly chitinized abdominal conjunctive areas, which resulted in exuviae breaking apart and sinking. Examination of untreated, dewaxed and dewaxed-deproteinized exuviae indicated that untreated exuviae sank faster. Waxes appeared important for colonization and initial microbial metabolization was delayed when waxes were removed. Results confirm the importance of biological degradation of exuviae in determining floatation times. We predict that streams and other waterbodies with high dissolved nutrients will result in rapidly sinking exuviae, while exuviae in low nutrient waterbodies will float longer. Article submitted 1. October 2014, accepted 18. November 2014, published 22. December 2014.
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Survivorship and longevity of adult Diamesa mendotae Muttkowski, 1915 (Diptera: Chironomidae) at controlled, sub-freezing temperatures
Aquatic Insects, 2014Co-Authors: Jane E. Mazack, Alyssa M. Anderson, Petra Kranzfelder, R. William Bouchard, James A. Perry, Bruce Vondracek, Leonard C. FerringtonAbstract:Diamesa mendotae Muttkowski, 1915 is a winter-active species common in groundwater-buffered streams of Minnesota and Wisconsin. This species is capable of surviving under snow cover for at least 28 days. Field collections of adult D. mendotae were used to determine survivorship under long-term exposure to controlled sub-freezing conditions. Specimens were placed into a controlled temperature chamber at −5 °C, batches removed at weekly intervals, and subsequently held at 6 °C to determine survivorship and longevity. Our results indicate that overall survivorship is negatively related to treatment duration of sub-freezing treatment, individuals can survive sub-freezing temperatures for at least 70 days, with total longevity of 92 days. Additionally, males had a significantly higher rate of survivorship than females within treatments. Total longevity increased with treatment time, suggesting adult D. mendotae may survive long periods of below-freezing temperatures under natural conditions before mating, whic...
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Survivorship and longevity of Diamesa mendotae Muttkowski (Diptera: Chironomidae) under snow
Journal of Entomological and Acarological Research, 2013Co-Authors: Alyssa M. Anderson, R W Bouchard, Petra Kranzfelder, Leonard C. FerringtonAbstract:Diamesa mendotae Muttkowski commonly grow and emerge from groundwater dominated streams in winter. Previous estimates of longevity for adults of D. mendotae collected from the snow surface averaged 18.6 days post-collection, with 76.9% of individuals dying between Day 10 and Day 30 post-collection and 4.4% surviving over 40 days. Maximum longevities for males and females were 48 and 54 days, respectively. In this paper, we report survivorship and longevity of fieldcollected adults of D. mendotae kept at ambient snow temperature conditions. Adults (n=140) were collected in February from snow along groundwater-dominated sections of the Kinnickinnic River (Wisconsin, USA). All individuals were placed in vials, buried in snow, and retrieved in batches of 10 males and 10 females at 4-day intervals for 28 days. Once retrieved, adults were maintained at 6°C in controlled environmental chambers to determine survivorship and longevity. All individuals survived snow burial treatment, indicating they are capable of surviving sub-freezing field conditions for at least 28 days. Estimates of adult maximum longevity were as high as 66 days, higher than previous estimates for this genus. Our results suggest adults of D. mendotae can persist under snow cover, with high survivorship and longevity, potentially increasing their probability of successful reproduction in regions where lethal winter air temperatures occur.
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cold hardiness in the adults of two winter stonefly species allocapnia granulata claassen 1924 and a pygmaea burmeister 1839 plecoptera capniidae
Aquatic Insects, 2009Co-Authors: R W Bouchard, Brian E Schuetz, Leonard C. Ferrington, Stephen A KellsAbstract:The supercooling points (SCPs) and lower lethal temperatures (LLT50) of adult males and females of Allocapnia granulata and A. pygmaea (Plecoptera: Capniidae) were determined for field-collected individuals from streams in central Minnesota (USA). Mean SCPs (±SE) for A. granulata females was −13.15°C (±0.44) and −11.95°C (±0.47) for A. pygmaea females. Using probit analysis, the LLT50 (±SE) for females of A. granulata was determined to be −8.50°C (±0.63) and −9.26°C (±0.57) for A. pygmaea. Mean LLT50s were higher than their respective SCPs, indicating that these species are not freeze tolerant and may be chill susceptible. SCPs for both Allocapnia species were lower than many other winter-emerging species, but were considerably higher than a species of Chironomidae (Diamesa mendotae: −21.6°C) often found in the same habitats. These results indicate that these Allocapnia species are moderately cold hardy, but are not well suited to mid-winter temperatures in Minnesota.
Alexander M. Milner - One of the best experts on this subject based on the ideXlab platform.
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Vulnerability of alpine stream biodiversity to shrinking glaciers and snowpacks
Global Change Biology, 2007Co-Authors: Lee E. Brown, David M. Hannah, Alexander M. MilnerAbstract:Climate change poses a considerable threat to the biodiversity of high latitude and altitude ecosystems, with alpine regions across the world already showing responses to warming. However, despite probable hydrological change as alpine glaciers and snow- packs shrink, links between alpine stream biota and reduced meltwater input are virtually unknown. Using data from the French Pyrenees, we demonstrate that taxonomic richness and total abundance of stream macroinvertebrates increase significantly as meltwater (snow melt and glacier melt) contributions to river flow decrease. Macro- invertebrate species showed a gradation of optimum meltwater conditions at which they persist. For example: Habroleptoides berthelemyi (Ephemeroptera), Perla grandis (Plecop- tera) and Rhithrogena spp. (Ephemeroptera) increased in abundance when meltwater contributions to streamflow decrease, whereas in contrast, Rhyacophila angelieri (Tri- choptera) and Diamesa latitarsis spp. (Diptera) decreased in abundance. Changes in alpine stream macroinvertebrate community composition as meltwater contributions decline were associated with lower suspended sediment concentration, and higher water temperature, electrical conductivity and pH. Our results suggest a diversity (at a site) of streams presently fed by meltwaters will increase with future meltwater reductions. However, b diversity (between-sites) will be reduced as snow melt and glacier melt decrease because the habitat heterogeneity associated with spatiotemporal variability of water source contributions will become lower as meltwater contributions decline. Extinction of some endemic alpine aquatic species (such as the Pyrenean caddis fly R. angelieri) is predicted with reduced meltwater inputs, leading to decreases in c diversity (region). Our identification of significant links between meltwater production and stream macroinvertebrate biodiversity has wider implications for the conservation of alpine river ecosystems under scenarios of climate change induced glacier and snowpack loss.
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The influence of glacial runoff on stream macroinvertebrate communities in the Taillon catchment, French Pyrénées
Freshwater Biology, 2001Co-Authors: Deborah L. Snook, Alexander M. MilnerAbstract:1. Benthic communities were sampled from five sites within a glacial catchment in the Cirque du Gavaranie, French Pyrenees, over two consecutive years (i) to investigate whether longitudinal patterns in zoobenthic communities exist downstream of a glacial margin and (ii) to identify the principal environmental variables influencing such patterns. 2. There was a distinct zonation of communities with increasing distance from the glacial margin. Ordination of the zoobenthic distribution indicated sites were separated by the relative contributions of taxa rather than their presence or absence. A shift in community composition and diversity separated a kryal type community dominated by Diamesa spp., Prosimulium spp., Eriopterini and Empididae at ≥2200 m a.s.l., from a more rhithral community of Orthocladiinae, Ephemeroptera, Plecoptera and Trichoptera at 1900 m a.s.l. 3. Chironomidae showed a defined gradient in distribution from Pseudokiefferiella parva and Diamesa latitarsis groups close to the glacier, through D. zernyi and D. cinerella groups, Orthocladius, Parametriocnemus and Micropsectra further downstream with Rheocricotopus, Corynoneura and Nilotanypus furthest from the glacial margin. Diamesa cinerella/zernyi group was the most euryzonal taxon. 4. Gradients in channel and hydraulic stability, groundwater input and mean water temperature were identified as the principal environmental variables associated with the downstream distribution gradient of zoobenthos. Diamesa, Empididae, Eriopterini and Nematoda were most tolerant of channel and hydraulically unstable and cold water habitats. Simuliidae (Prosimulium), Crenobia alpina, Rhyacophila, Chaetopterygini, Drusus rectus, Capnioneura, Orthocladius and Parametriocnemus were associated with intermediate conditions. Corynoneura, Tanypodinae, Perlidae, Chloroperlidae, Agapetus fuscipes and Coleoptera were least tolerant of channel and hydraulic instability and low water temperature.
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Macroinvertebrate stream communities along regional and physico‐chemical gradients in Western Greenland
Freshwater Biology, 2001Co-Authors: Nikolai Friberg, Claus Lindegaard, Alexander M. Milner, L.m. Svendsen, Søren Ejling LarsenAbstract:1. Macroinvertebrates were collected and physico-chemical variables measured at 16 stream sites in Western Greenland during July 1999. Eight sites were located on Disko Island in an arctic oceanic climate and eight sites in the Kangerlussuaq area close to the icecap where the climate is arctic continental. The streams had different water sources (glacial, groundwater, snowmelt and lake water). 2. The streams showed pronounced differences in water temperature (2.2–17.3 °C), concentrations of suspended solids (0–2400 mg L−1), and conductivity (10–109 μS cm−1). Principal component analysis (PCA) analysis of the physico-chemical variables separated the Disko Island sites into a distinct group, whereas the sites in the Kangerlussuaq area were more dispersed. 3. A total of 56 macroinvertebrate species were found, including 31 species of Chironomidae, the most abundant of which was Orthocladius thienemanni. Diamesa sp. was only the sixth most abundant chironomid taxon. Species composition varied between sites, and abundance varied from about 20 individuals m−2 in a glacier fed stream to more than 16 000 m−2 in a lake outlet. 4. The macroinvertebrate communities of the 16 streams were separated into five TWINSPAN groups reflecting water source, irrespective of region. Lake outlets and ground-water-fed streams had the highest species richness and abundance, temperature and bed stability, while glacier-fed streams were characterized by low species richness, abundance, temperature, bed stability and high concentrations of suspended solids. Macroinvertebrate species richness was positively correlated with water temperature and negatively with bed stability. Conductivity was positively correlated with invertebrate abundance. 5. The results of this study suggest that the source of stream water can be used to predict invertebrate community composition in Greenlandic streams and thus the effects of changes in water balance and flow regime, and to identify sites of special conservation interest.
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Macroinvertebrate community succession in Wolf Point Creek, Glacier Bay National Park, Alaska
Freshwater Biology, 2000Co-Authors: E. A. Flory, Alexander M. MilnerAbstract:Summary 1 Macroinvertebrate community development in Wolf Point Creek in Glacier Bay National Park, Alaska formed by ice recession was investigated from 1991 to 1994 as part of a long-term study of colonization now exceeding 20 years. Chironomidae, the first taxon to colonize the stream, still dominated the community comprising 75–95% by number, but species succession was apparent. 2 Species richness in August increased from five species in 1978 to 11 in 1991 and 16 in 1994. 3 Diamesa species, abundant in 1978 at densities exceeding 2 750 m-2, were not collected in 1994, while Pagastia partica dominated the community with densities exceeding 10 000 m-2. 4 Sixteen taxa, never previously collected, colonized the stream between 1991 and 1994 including representatives of Coleoptera, Muscidae, Trichoptera, and the first noninsect taxon, Oligochaeta. Colonization by new taxa was associated with an increase in summer water temperature and the development of riparian vegetation. 5 Inter-specific competition is suggested as a possible factor in species succession and is incorporated into a taxa richness model of community development in postglacial streams incorporating stable and unstable channels.
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The role of competition in invertebrate community development in a recently formed stream in Glacier Bay National Park, Alaska
Aquatic Ecology, 1999Co-Authors: E. A. Flory, Alexander M. MilnerAbstract:New streams formed following ice recession in Glacier Bay National Park, southeastern Alaska allow insights into the role of abiotic and biotic interactions in the assemblage of benthic communities. Reductions in abundance of a pioneer chironomid colonizer, Diamesa alpina/lupus, in one new stream, Wolf Point Creek, is considered to be a result of competitive interactions with subsequent colonizers, as opposed to intolerance of warmer water temperature as previously suggested. Reduced densities of potential competitors (25–50 larvae per 500 cm^2) in a cobble transplant experiment between streams, allowed persistence of D. alpina/lupus at low densities. In addition, significantly more D. alpina/lupus larvae emigrated from artificial stream channels containing other chironomid taxa than channels without potential competitors while there was no significant correlation of emigration with water temperature. A small number of D. alpina/lupus transplanted from a cold stream (4–6 °C) survived at water temperatures of 10–15 °C for 1 week. These results infer that interference competition is the causal mechanism in the decline of D. alpina/lupus. Complete exclusion of D. alpina/lupus from the stream has not occurred and water temperature may play a role in partitioning D. alpina/lupus from other taxa on a temporal or a spatial basis.
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A long noncoding RNA acts as a post-transcriptional regulator of heat shock protein (HSP70) synthesis in the cold hardy Diamesa tonsa under heat shock.
PloS one, 2020Co-Authors: Paola Bernabò, Gabriella Viero, Valeria LencioniAbstract:Cold stenothermal insects living in glacier-fed streams are stressed by temperature variations resulting from glacial retreat during global warming. The molecular aspects of insect response to environmental stresses remain largely unexplored. The aim of this study was to expand our knowledge of how a cold stenothermal organism controls gene expression at the transcriptional, translational, and protein level under warming conditions. Using the chironomid Diamesa tonsa as target species and a combination of RACE, qPCR, polysomal profiling, western blotting, and bioinformatics techniques, we discovered a new molecular pathway leading to previously overlooked adaptive strategies to stress. We obtained and characterized the complete cDNA sequences of three heat shock inducible 70 (hsp70) and two members of heat-shock cognate 70 (hsc70). Strikingly, we showed that a novel pseudo-hsp70 gene encoding a putative long noncoding RNA (lncRNA) which is transcribed during thermal stress, acting as a ribosome sponge to provide post-transcriptional control of HSP70 protein levels. The expression of the pseudo-hsp70 gene and its function suggest the existence of a new and unexpected mechanism to cope with thermal stress: lowering the pace of protein production to save energy and optimize resources for recovery.
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A long noncoding RNA acts as a post-transcriptional regulator of heat shock protein 70 kDa synthesis in the cold hardy Diamesa tonsa under heat shock
2019Co-Authors: Valeria Lencioni, Paola Bernabò, Gabriella VieroAbstract:Cold stenothermal insects living in glacier-fed streams are stressed by temperature variations resulting from glacial retreat during global warming. The molecular aspects of insect response to environmental stresses remain largely unexplored. The aim of this study was to expand our knowledge of how a cold stenothermal organism controls gene expression at the transcriptional, translational, and protein level under warming conditions. Using the chironomid Diamesa tonsa as target species and a combination of RACE, qPCR, polysomal profiling, western blotting, and bioinformatics techniques, we discovered a new molecular pathway leading to previously overlooked adaptive strategies to stress. We obtained and characterized the complete cDNA sequences of three heat shock inducible 70 ( hsp70 ) and two members of heat-shock cognate 70 ( hsc70 ). Strikingly, we showed that a novel pseudo-hsp70 gene encoding a putative long noncoding RNA (lncRNA) which is transcribed during thermal stress, acting as a ribosome sponge to provide post-transcriptional control of HSP70 protein levels. The expression of the pseudo-hsp70 gene and its function suggest the existence of a new and unexpected mechanism to cope with thermal stress: lowering the pace of protein production to save energy and optimize resources for recovery.
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Response of Diamesa spp. (Diptera: Chironomidae) from Alpine streams to newly emergent contaminants and pesticides
Journal of Limnology, 2018Co-Authors: Valeria Lencioni, Francesco Bellamoli, Paola Bernabò, Francesco Miari, Alberto ScottiAbstract:Acute toxicity and genotoxic activity of 11 pollutants were investigated in wild populations of Diamesa cinerella and Diamesa zernyi (Diptera Chironomidae) from two alpine streams (Italian Alps). D. cinerella was collected in two sites on the non-glacial Vermigliana stream, 50 m-upstream and 5-m downstream of the Wastewater Treatment Plant (WTP) at the Tonal Pass (1799 m a.s.l.). D. zernyi was collected in the Presena glacial stream, close to the glacier snout (2685 m a.s.l.). IV-instar larvae were exposed for 24-96 h to increasing concentrations of three drugs (ibuprofen-IBU, furosemide-FUR, trimethoprim-TMP), three personal care products (triclocarban-TCC, tonalid-TON, sucralose-SUCR), and five pesticides (boscalid-BOS, captan-CAP, chlorpyrifos-CPS, metolachlor-MET, terbuthylazine-TER). The experimental concentrations were from one to several million times higher than the highest environmental concentration (EC) measured in the study sites. Two mixtures of pesticides were also prepared: MIX 1K =103 x EC of CPS, MET and TER, and MIX 10K = 104 x EC of CPS, MET and TER. Species- and site-specific responses were observed for both tests. On the basis of survival data, both species resulted very resistant to pharmaceuticals (mainly to FUR for which no effects on survival and movement or pupation were observed), and more sensitive to pesticides (mainly to CPS, MET and CAP). Genotoxicity tests (Comet assay) highlighted a WTP effect under natural conditions and a genotoxic effect for 9 of the 11 tested compounds. Overall, a clear gradient of increasing resistance in larvae from the least (PR0) to the most polluted (TP_dw) site was highlighted by both tests, ecotoxicological and of genotoxicity, as also expected according to species autecology (D. zernyi is restricted to very cold and pristine habitats). D. cinerella living downstream of the effluent accumulates a significantly higher DNA damage than the other populations, highlighting a basal physiological stress condition in nature. It is plausible that these larvae possess chemical resistance strategies to survive already under natural conditions. Diamesa spp. exhibited a higher toxic resistance than any other model species tested to date under the same pollutants, probably associable to its strong cold resistance. The results emphasised that the measured concentrations of Contaminants of Emerging Concern (CECs) and pesticides seem to be far below those required to cause acute effects. However, the effects on freshwater communities of prolonged exposure to mixture of trace CECs and pesticides remain unknown.
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Cold adaptive potential of chironomids overwintering in a glacial stream
Physiological Entomology, 2015Co-Authors: Valeria Lencioni, Olivier Jousson, Graziano Guella, Paola BernabòAbstract:Insects inhabiting cold streams must either tolerate or avoid freezing to survive. The present study reports the strategy adopted by fourth-instar larvae of two chironomid species [PseudoDiamesa branickii (Nowicki) and Diamesa cinerella (Meigen)] overwintering in a glacial stream (in the Italian Alps). The cold adaptive potential of both species under acute cold stress is investigated down to –30 °C. Supercooling points, lower lethal temperatures (LLTs), haemolymph thermal hysteresis, whole body content of sugars and polyols, and the expression of heat shock protein (HSP) genes (hsc70 and hsp70) expression are estimated. Comparable thermal hysteresis (> 2 °C) is measured in the two species, both of which accumulate glucose and sucrose as the main cryoprotectants. According to the supercooling points (= –6.37 and –6.85 °C, respectively) and LLT100 (= –16.2 and –14.7 °C, respectively), P. branickii and D. cinerella can both be considered as freeze tolerant. However, the cumulative proportion of individual freezing values and the LLT50 (–9.14 and –6.13 °C, respectively) suggest that P. branickii is more cold hardy than D. cinerella, whereas the gene expression data (i.e. an absence of up-regulation of hsp70 in D. cinerella) suggest that D. cinerella is more cold hardy than P. branickii. These findings are discussed in relation to the validity of the different metabolic indicators for defining the level of cold hardiness of a species, even in relation to its cold stenothermy. The results are also discussed in relation to climate warming, which represents a serious threat for species from glacier-fed streams.
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Thermal stress induces HSP70 proteins synthesis in larvae of the cold stream non-biting midge Diamesa cinerella Meigen.
Archives of insect biochemistry and physiology, 2013Co-Authors: Valeria Lencioni, Paola Bernabò, Michele Cesari, Lorena RebecchiAbstract:Laboratory experiments on the cold stenothermal midge Diamesa cinerella (Diptera, Chironomidae) were performed to study the relationship between increasing temperature and heat shock proteins (HSP70) expression at translational level (Western blotting). Thermotolerance of IV instar larvae collected in nature at 1.5–4.3°C during seasons was analyzed through short-term (1 h at ten different temperatures from 26°C to 35°C) and long-term (1–14 h at 26°C and 1–4 h at 32°C) heat shocks. A high thermotolerance was detected (LT50 = 30.9–32.8°C and LT100 = 34.0–37.8°C). However, survival decreased consistently with increasing exposure time, especially at higher temperature (LTime50 = 7.64 h at 26°C and LTime50 = 1.73 h at 32°C). The relationship between such heat resistance and HSP70 expression appeared evident because a relationship between HSP70 level and larval survival rate was generally found. A heat shock response (HSR) was consistent only in the summer larvae. The absence of HSR in the other populations coupled with even higher amounts of HSP70 than in summer, led us to hypothesize that other macromolecules and other adaptive mechanisms, apart from biochemical ones, are involved in the response of D. cinerella larvae to high temperature. Altogether these results stressed how in this midge the HSP70 protein family confers resistance against cold, being detected under natural conditions in control larvae collected in all seasons, but also against warm under experimental heat shocks. These results give new insights into possible responses to climate changes in freshwater insects within the context of global warming.