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1.
Zootaxa ; 5052(1): 128-136, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34810883

RESUMO

Kribiodorum is a small genus of non-biting midges, currently composed of only five nominal species, one Nearctic, two African and two Oriental. The objective of this study is to provide the first report of this genus to the Neotropical region and to describe a new species, based on male and female from southern Amazonas state, Brazil. Kribiodorum amazonicum sp. n. is easily distinguished from the congeneric species by the color pattern of the wings and legs and by the morphology of the genitalia.


Assuntos
Chironomidae , Dípteros , Animais , Brasil , Feminino , Masculino , Floresta Úmida
2.
Zootaxa ; 5020(3): 550-560, 2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34810988

RESUMO

Palpomyia auakua, a new predaceous midge in the Palpomyia distincta group, is described and illustrated from females collected with Malaise trap in a cloud forest at 1470 m. in Tlanchinol, Hidalgo, Mexico. This new species is compared with three Neotropical species, Palpomyia paulistensis Lane and P. castanea Macfie from Brazil, and P. yamana Spinelli et al. from Tierra del Fuego, and its similar Nearctic species P. jamnbacki Grogan Wirth. Also included the first record of P. aspina Grogan Wirth from Mexico and Guatemala, and new records of P. subaspera (Coquillett) from Veracruz and Tabasco. A key to males and females of species of Palpomyia that inhabit Mexico is also included.


Assuntos
Ceratopogonidae , Chironomidae , Dípteros , Animais , Feminino , Masculino , México
3.
Ecotoxicology ; 30(10): 2119-2131, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34623547

RESUMO

To ascertain the tolerance mechanisms of aquatic organisms to artificial chemicals, intergenerational sensitivity changes of Chironomus yoshimatsui to a carbamate pesticide (pirimicarb) and pharmaceutical chemical (diazepam) were investigated. The larvae (<48-h-old) in each generation were exposed to both chemicals for 48 h and then the surviving chironomids were cultured until the fifth generation (F0-F4) without chemical addition. The 48-h 50% effective concentration (EC50) value of chironomids was determined for each generation. In the pirimicarb treatment group, the EC50 values significantly increased in F3 and F4, and those in the diazepam treatment group slightly increased. Catalase, Cytochrome P450 and hemoglobin (Hb) mRNA levels were monitored to see whether these were related to the trans-generational sensitivity. Although the generalized linear model results showed that the sensitivity to diazepam was slightly increased in the diazepam treatment, we could not find any mRNA levels related to sensitivity alteration. In contrast, the model approach showed that the chironomids exposed to pirimicarb trans-generationally became tolerant with increasing Hb mRNA levels. Therefore, they might decrease their chemical stress by modifying Hb gene transcription.


Assuntos
Chironomidae , Preparações Farmacêuticas , Poluentes Químicos da Água , Animais , Carbamatos/toxicidade , Catalase , Chironomidae/genética , Sistema Enzimático do Citocromo P-450/genética , Hemoglobinas/genética , Larva , Transcrição Genética , Poluentes Químicos da Água/toxicidade
4.
Int J Mol Sci ; 22(19)2021 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-34638651

RESUMO

The telomeric transcriptome of Chironomus riparius has been involved in thermal stress response. One of the telomeric transcripts, the so-called CriTER-A variant, is highly overexpressed upon heat shock. On the other hand, its homologous variant CriTER-B, which is the most frequently encoded noncoding RNA in the telomeres of C. riparius, is only slightly affected by thermal stress. Interestingly, both transcripts show high sequence homology, but less is known about their folding and how this could influence their differential behaviour. Our study suggests that CriTER-A folds as two different conformers, whose relative proportion is influenced by temperature conditions. Meanwhile, the CriTER-B variant shows only one dominant conformer. Thus, a temperature-dependent conformational equilibrium can be established for CriTER-A, suggesting a putative functional role of the telomeric transcriptome in relation to thermal stress that could rely on the structure-function relationship of the CriTER-A transcripts.


Assuntos
Chironomidae/genética , RNA não Traduzido/genética , Telômero/genética , Transcriptoma/genética , Animais , Sequência de Bases , Resposta ao Choque Térmico/genética , Temperatura Alta
5.
Oecologia ; 197(2): 373-385, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34596750

RESUMO

Microhabitats with distinct biotic and abiotic properties exist within landscapes, and this microhabitat variation can have dramatic impacts on the phenology and physiology of the organisms occupying them. The Antarctic midge Belgica antarctica inhabits diverse microhabitats along the Western Antarctic Peninsula that vary in macrophyte composition, hygric qualities, nutrient input, and thermal patterns. Here, we compare seasonal physiological changes in five populations of B. antarctica living in close proximity but in different microhabitats in the vicinity of Palmer Station, Antarctica. Thermal regimes among our sample locations differed in both mean temperature and thermal stability. Between the warmest and coldest sites, seasonal mean temperatures differed by 2.6˚C and degree day accumulations above freezing differed by a factor of 1.7. Larval metabolic and growth rates varied among the sites, and adult emergence occurred at different times. Distinct microhabitats also corresponded with differences in body composition, as lipid and carbohydrate content of larvae differed across sites. Further, seasonal changes in carbohydrate and protein content were dependent on site, indicating fine-scale variation in the biochemical composition of larvae as they prepare for winter. Together, these results demonstrate that variation in microhabitat properties influences the ontogeny, phenology, physiology, and biochemical makeup of midge populations living in close proximity. These results have implications for predicting responses of Antarctic ecosystems to environmental change.


Assuntos
Chironomidae , Ecossistema , Animais , Regiões Antárticas , Temperatura Baixa , Congelamento
6.
Environ Monit Assess ; 193(10): 686, 2021 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-34599687

RESUMO

Biological inventories combined with the estimation of species richness represent a useful tool for the analysis of the pattern of species distribution in different regions. This study aimed to (i) comparatively evaluate the performance of non-parametric richness estimators for invertebrate inventories in reservoirs between ecoregions and (ii) to assess whether the efficiency (bias, precision and accuracy indices) of the estimators is altered when applied to sites from different ecoregions. The study was conducted in the ecoregions Central Pediplano of the Borborema Plateau (Paraíba River basin) and Northern Sertaneja Depression (Piranhas-Assu River basin), semiarid region of Brazil. Six reservoirs were selected and benthic macroinvertebrates were sampled at 141 sites distributed along the littoral zone, in 4 periods (June, September, December 2014 and March 2015). The organisms were identified to the family level, except for Chironomidae, identified to the genus level. We comparatively analyzed six non-parametric richness estimators: Jackknife 1, Jackknife 2, Chao1, Chao 2, ICE, and Bootstrap, and three performance indicators: bias, precision, and accuracy. ICE and Jackknife 2 had more stable results for total species richness, but with different performance between ecoregions for bias, precision, and accuracy. Variation in performance of the estimators may be associated with differences in species richness and frequency between ecoregions. ICE and Jackknife 2 proved to be the best estimators for biological inventories of aquatic invertebrates in reservoirs in studies comparing data from different ecoregions, due to accuracy and precision, while Bootstrap is the least indicated, given greater bias and less accuracy and precision.


Assuntos
Chironomidae , Monitoramento Ambiental , Animais , Brasil , Invertebrados , Rios
7.
Rev Environ Contam Toxicol ; 259: 77-122, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34661753

RESUMO

In freshwater ecosystems, aquatic invertebrates are influenced continuously by both physical stress and xenobiotics. Chironomids (Diptera; Chironomidae), or non-biting midges, are the most diverse and abundant invertebrates in freshwater habitats. They are a fundamental link in food chains of aquatic ecosystems. Chironomid larvae tolerate stress factors in their environments via various physiological processes. At the molecular level, environmental pollutants induce multi-level gene responses in Chironomus that regulate cellular protection through the activation of defense processes. This paper reviews literature on the transcriptional responses of biomarker genes to environmental stress in chironomids at the molecular level, in studies conducted from 1991 to 2020 (120 selected literatures of 374 results with the keywords "Chironomus and gene expression" by PubMed search tool). According to these studies, transcriptional responses in chironomids vary depending on the type of stress factor and defensive responses associated with antioxidant activity, the endocrine system, detoxification, homeostasis and stress response, energy metabolism, ribosomal machinery, apoptosis, DNA repair, and epigenetics. These data could provide a comprehensive overview of how Chironomus species respond to pollutants in aquatic environments. Furthermore, the transcriptomic data could facilitate the development of genetic tools for water quality and environmental monitoring based on resident chironomid species.


Assuntos
Chironomidae , Poluentes Químicos da Água , Animais , Chironomidae/genética , Ecossistema , Expressão Gênica , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Qualidade da Água
8.
Environ Pollut ; 290: 118061, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34523523

RESUMO

Pesticides used in agriculture can be transported at a medium-high distance due to the drift effect, reaching even remote areas as mountain regions, glaciers, and snow cover. With the melting process, pesticides enter freshwater glacier ecosystems, becoming a threat to wildlife fauna, mainly dominated by Diptera Chironomidae. Chlorpyrifos (CPF), as one of the most commonly used pesticides in alpine vineyards and apple orchards, is frequently detected in icemelt waters. We selected as target species, larvae of the cold stenothermal chironomid Diamesa zernyi, collected in two glacier-fed streams (Presena and Amola) in the Italian Alps. Firstly, a de novo transcriptome was obtained, and secondly, a gene array was designed to study the molecular response of a wild population of D. zernyi exposed to three sub-lethal CPF concentrations corresponding to 1/100 LC10 (0.011 µg/L), 1/10 LC10 (0.11 µg/L), and LC10 (1.1 µg/L), for 24 h. The sub-organismal response was evaluated by Real-Time Polymerase Chain Reaction (RT-PCR), employing 40 genes related to essential metabolic routes as future candidates for biomarkers in wildlife chironomids. After 24 h, the endocrine system (E75, E93, EcR, and Met), detoxification response (GSTO3, GSTS1), and stress response (hsp75, hsp83, HYOU1) were altered. CPF seems to act as an endocrine disruptor and could lead to defective larval development, disrupted cellular homeostasis through heat shock proteins (HSPs) alteration (defective protein folding and mitochondrial functions), as well as oxidative damage (confirmed by increased GST expression). For the first time, molecular studies detected early alarm signals in wildlife in glacier environments. Our findings confirm the high environmental risk of CPF affecting aquatic insect metabolism and raise the level of concern about this pesticide in high altitude water bodies, generally considered pristine. Furthermore, this study emphasizes the incipient need to use non-model organisms for the evaluation of natural ecosystems. We also highlight the demand for research into new molecular biomarkers, and the importance of including molecular approaches in toxicology evaluations to detect the early adverse effects of pollutants.


Assuntos
Chironomidae , Clorpirifos , Poluentes Químicos da Água , Animais , Biomarcadores , Clorpirifos/toxicidade , Ecossistema , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
9.
An Acad Bras Cienc ; 93(suppl 3): e20200860, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34550199

RESUMO

The use of agrochemicals in agriculture may impact aquatic ecosystems, particularly influencing the stream insect communities. Among aquatic insects, the family Chironomidae is the most abundant and species-diverse insect group found in freshwater ecosystems. However, in the southern hemisphere, studies with Chironomidae are still sparse, compared to Europe and North America. The present study evaluates the responses of Chironomidae species (Insecta: Diptera) to pyrimethanil fungicide in a mesocosm experiment. Water contamination and chironomid community were monitored over 10 months. After five months of monitoring, the pyrimethanil fungicide was completely degraded and there was a statistically significant increase in the Margalef Richness and Shannon-Wiener Index (H') in the control units when compared with the contaminated mesocosms (p = 0.003). Our results point out that the utilization of agrochemicals can be a harmful factor influencing negatively the Chironomidae populations. This finding has key implications for insect conservation strategies and ecological management environments.


Assuntos
Chironomidae , Fungicidas Industriais , Animais , Ecossistema , Fungicidas Industriais/toxicidade , Pirimidinas/toxicidade
10.
Environ Sci Technol ; 55(20): 13990-13999, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34590483

RESUMO

The aim of this study is to compare the azole synergy across an insect, Chironomus riparius, and a crustacean species, Daphnia magna. We use a combination of in vivo measurements of cytochrome P450 monooxygenase (CYP) biotransformation potential and toxicokinetic (TK) and toxicodynamic (TD) modeling to understand the mechanism behind the synergy of two azole fungicides: the imidazole prochloraz and the triazole propiconazole on the pyrethroid insecticide α-cypermethrin. For both species, the synergistic effect of prochloraz was well-described by its effect on in vivo CYP activity, which corresponded to the biotransformation rate of the TK model parameterized on the survival data of the mixture experiment. For propiconazole, however, there were 100-fold and 50-fold differences between the 50% effect concentration of in vivo CYP activity and the modeled biotransformation rate for C. riparius and D. magna, respectively. Propiconazole, therefore, seems to induce synergy through a mechanism that cannot be quantified solely by the CYP activity assay used in this study in either of the two species. We discuss the differences between prochloraz and propiconazole as synergists across the two species in the light of the type and time dynamics of affected biotransformation processes.


Assuntos
Chironomidae , Fungicidas Industriais , Poluentes Químicos da Água , Animais , Azóis , Daphnia
11.
Ecology ; 102(11): e03513, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34365638

RESUMO

Ecosystem engineers have large impacts on the communities in which they live, and these impacts may feed back to populations of engineers themselves. In this study, we assessed the effect of ecosystem engineering on density-dependent feedbacks for midges in Lake Mývatn, Iceland. The midge larvae reside in the sediment and build silk tubes that provide a substrate for algal growth, thereby elevating benthic primary production. Benthic algae are in turn the primary food source for the midge larvae, setting the stage for the effects of engineering to feed back to the midges themselves. Using a field mesocosm experiment manipulating larval midge densities, we found a generally positive but nonlinear relationship between density and benthic production. Furthermore, adult emergence increased with the primary production per midge larva. By combining these two relationships in a simple model, we found that the positive effect of midges on benthic production weakened negative density dependence at low to intermediate larval densities. However, this benefit disappeared at high densities when midge consumption of primary producers exceeded their positive effects on primary production through ecosystem engineering. Our results illustrate how ecosystem engineering can alter density-dependent feedbacks for engineer populations.


Assuntos
Chironomidae , Ecossistema , Animais , Retroalimentação , Insetos , Lagos
12.
J Insect Physiol ; 133: 104288, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34343520

RESUMO

Larvae of chironomid Chironomus sulfurosus mainly live in acidic rivers near hot springs, suggesting that they naturally select acidic environments as preferred habitats. Here we showed that C. sulfurosus larvae moved toward acidic areas and stayed alive on agar gels with a pH gradient of H2SO4, and the body fluid pH of the homogenized larvae was near neutral even acclimated under the acidic conditions, indicating mechanisms for acid tolerance. In order to gain insights into this mechanism at the molecular level, de novo RNA-seq analysis was performed on C. sulfurosus larvae. As a result, 1,208 genes were found to be significantly up-regulated in larvae acclimated at pH 2.0 compared to controls at pH 7.0. Among the up-regulated genes, ones encoding cuticle proteins, peritrophic matrix proteins, mucus-forming proteins, F-type ATPase subunits, glutathione S transferases, ß-1,3-D-glucan synthetase, hemoglobin, and cytochrome P450 were identified. This transcriptome analysis in conjunction with behavioral and biochemical assays expands our knowledge of gene expression in C. sulfurosus larvae living in acidic environments, which will provide a basis for further studies to elucidate the molecular mechanisms for acid tolerance employed by organisms in nature.


Assuntos
Chironomidae/fisiologia , Água Doce/química , Genes de Insetos , Proteínas de Insetos/metabolismo , Transcriptoma , Ácidos/metabolismo , Animais , Chironomidae/genética , Chironomidae/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Concentração de Íons de Hidrogênio , Larva/genética , Larva/crescimento & desenvolvimento , Larva/fisiologia
13.
Aquat Toxicol ; 239: 105940, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34455205

RESUMO

Non-biting midges are dominant species in aquatic systems and often used for studying the toxicological researches of insecticides. ATP-binding cassette (ABC) transporters represent the largest known members in detoxification genes but is little known about their function in non-biting midges. Here, we selected Propsilocerus akamusi, widespread in urban streams, to first uncover the gene structure, location, characteristics, and phylogenetics of chironomid ABC transporters at genome-scale. Fifty-seven ABC transporter genes are located on four chromosomes, including eight subfamilies (ABCA-H). The ABCC, ABCG, and ABCH subfamilies experienced the duplication events to different degrees. The study showed that expression of the PaABCG17 gene is uniquely significantly elevated, with deltamethrin concentration increasing (1, 4, and 20 ug/L) both in RNA-seq and qPCR results. Additionally, the ABC transporter members of other six chironomids with assembled genomes are first described and used to investigate the characteristic of those living in the different adverse habitats. The ABC transporter frame for Propsilocerus akamusi and its transcriptomic results lay an important foundation for providing valuable resources for understanding the ABC transporter function in insecticide toxification of this species as well as those of other non-biting midges. The PaABCG17 gene is shown to play an important role in deltamethrin detoxification, and it functions need to be further investigated and might be used in the management of insecticide-resistance in chironomid adults.


Assuntos
Chironomidae , Poluentes Químicos da Água , Transportadores de Cassetes de Ligação de ATP/genética , Trifosfato de Adenosina , Animais , Estudo de Associação Genômica Ampla , Nitrilas , Filogenia , Piretrinas , Poluentes Químicos da Água/toxicidade
14.
Sci Rep ; 11(1): 14979, 2021 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-34294865

RESUMO

Sinhuber et al. (Sci Rep 11:3773, 2021) formulated an equation of state for laboratory swarms of the non-biting midge Chironomus riparius that holds true when the swarms are driven through thermodynamic cycles by the application external perturbations. The findings are significant because they demonstrate the surprising efficacy of classical equilibrium thermodynamics for quantitatively characterizing and predicting collective behaviour in biology. Nonetheless, the equation of state obtained by Sinhuber et al. (2021) is anomalous, lacking a physical analogue, making its' interpretation problematic. Moreover, the dynamical processes underlying the thermodynamic cycling were not identified. Here I show that insect swarms are equally well represented as van der Waals gases and I attribute the possibility of thermodynamic cycling to insect swarms consisting of several overlapping sublayers. This brings about a profound change in the understanding of laboratory swarms which until now have been regarded as consisting of non-interacting individuals and lacking any internal structure. I show how the effective interactions can be attributed to the swarms' internal structure, the external perturbations and to the presence of intrinsic noise. I thereby show that intrinsic noise which is known to be crucial for the emergence of the macroscopic mechanical properties of insect swarms is also crucial for the emergence of their thermodynamic properties as encapsulated by their equation of state.


Assuntos
Comportamento Animal/fisiologia , Chironomidae/fisiologia , Animais , Fenômenos Biomecânicos , Relações Interpessoais , Modelos Biológicos , Estresse Fisiológico , Termodinâmica
15.
J Exp Biol ; 224(14)2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-34297110

RESUMO

Rapid hardening is a process that quickly improves an animal's performance following exposure to potentially damaging stress. In this study of the Antarctic midge, Belgica antarctica (Diptera, Chironomidae), we examined how rapid hardening in response to dehydration (RDH) or cold (RCH) improves male pre- and post-copulatory function when the insects are subsequently subjected to a damaging cold exposure. Neither RDH nor RCH improved survival in response to lethal cold stress, but male activity and mating success following sublethal cold exposure were enhanced. Egg viability decreased following direct exposure of the mating males to sublethal cold but improved following RCH and RDH. Sublethal cold exposure reduced the expression of four accessory gland proteins, while expression remained high in males exposed to RCH. Though rapid hardening may be cryptic in males, this study shows that it can be revealed by pre- and post-copulatory interactions with females.


Assuntos
Chironomidae , Aclimatação , Animais , Regiões Antárticas , Temperatura Baixa , Corte , Feminino , Fertilidade , Larva , Masculino
16.
Environ Pollut ; 289: 117848, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34332169

RESUMO

There is growing evidence of widespread contamination of freshwater ecosystems with microplastics. However, the effects of chronic microplastic ingestion and its interaction with other pollutants and stress factors on the life-history traits and the host-microbiome of aquatic invertebrates are not well understood. This study investigates the effects of exposure to sediment spiked with 1 µm polystyrene-based latex microplastic spheres, an environmentally realistic concentration of a pyrethroid pesticide (esfenvalerate), and a combination of both treatments on the life-history traits of the benthic-dwelling invertebrate, Chironomus riparius and its microbial community. The chironomid larvae were also exposed to two food conditions: abundant or limited food in the sediment, monitored for 28 and 34 days respectively. The microplastics and esfenvalerate had negative effects on adult emergence and survival, and these effects differed between the food level treatments. The microbiome diversity was negatively affected by the exposure to microplastics, while the relative abundances of the four top phyla were significantly affected only in the high food level treatment. Although the combined exposure to microplastics and esfenvalerate showed some negative effects on survival and emergence, there was little evidence for synergistic effects when compared to the single exposure. The food level affected all life-history traits and the microbiota, and lower food levels intensified the negative effects of the exposure to microplastics, esfenvalerate and their combination. We argue that these pollutants can affect crucial life-history traits such as successful metamorphosis and the host-microbiome. Therefore, it should be taken into consideration for toxicological assessment of pollutant acceptability. Our study highlights the importance of investigating possible additive and synergic activities between stressors to understand the effects of pollutants in the life story traits and host-microbiome.


Assuntos
Chironomidae , Microbiota , Piretrinas , Poluentes Químicos da Água , Animais , Microplásticos , Plásticos/toxicidade , Piretrinas/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
17.
Int J Mol Sci ; 22(11)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071490

RESUMO

The Pv11, an insect cell line established from the midge Polypedilum vanderplanki, is capable of extreme hypometabolic desiccation tolerance, so-called anhydrobiosis. We previously discovered that heat shock factor 1 (HSF1) contributes to the acquisition of desiccation tolerance by Pv11 cells, but the mechanistic details have yet to be elucidated. Here, by analyzing the gene expression profiles of newly established HSF1-knockout and -rescue cell lines, we show that HSF1 has a genome-wide effect on gene regulation in Pv11. The HSF1-knockout cells exhibit a reduced desiccation survival rate, but this is completely restored in HSF1-rescue cells. By comparing mRNA profiles of the two cell lines, we reveal that HSF1 induces anhydrobiosis-related genes, especially genes encoding late embryogenesis abundant proteins and thioredoxins, but represses a group of genes involved in basal cellular processes, thus promoting an extreme hypometabolism state in the cell. In addition, HSF1 binding motifs are enriched in the promoters of anhydrobiosis-related genes and we demonstrate binding of HSF1 to these promoters by ChIP-qPCR. Thus, HSF1 directly regulates the transcription of anhydrobiosis-related genes and consequently plays a pivotal role in the induction of anhydrobiotic ability in Pv11 cells.


Assuntos
Adaptação Fisiológica/genética , Chironomidae/genética , Dessecação , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla/métodos , Fatores de Transcrição de Choque Térmico/genética , Proteínas de Insetos/genética , Animais , Linhagem Celular , Chironomidae/citologia , Análise por Conglomerados , Perfilação da Expressão Gênica/métodos
18.
Environ Pollut ; 285: 117462, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34091266

RESUMO

The extent until which plastics are present in our surrounding environment completely exceeds our expectations. Plastic materials in the form of microplastics have been found in terrestrial, freshwater and marine environments and are transported through the atmosphere even to remote locations. However, we are still far from understanding the effects that they may have caused and are causing to biota. In the present study, we investigated the alterations in the expression of twelve genes in the aquatic insect Chironomus riparius after 36 h exposures to polystyrene and tire rubber microplastics at nominal concentrations of 1 and 10 mg L-1. The results indicated that several genes encoding for heat shock proteins (hsp90, Glycoprotein 93 (Gp93), hsc70, hsp60, hsp40, and the small HSP hsp17) were overexpressed respect to the control. In addition, the genes coding for manganese superoxide dismutase (SOD Mn, related to alleviation of oxidative stress) and for the FK506-binding protein of 39 kDa. (FKBP39, related to development and pupation) showed altered expression. Most of the alterations on gene expression level occurred at a concentration of 10 mg L-1 of tire rubber microplastics, although specific modifications arose at other concentrations of both rubber and polystyrene. On the contrary, one hsp gene (hsp10) and genes related to biotransformation and detoxification (Cyp9f2, Cyp12a2, and ABCB6) did not alter their expression in any of the treatments. Overall, the results of the gene expression indicated that microplastics (especially tire rubber) or their additives caused cellular stress that led to some alterations in the normal gene expression but did not cause any mortality after 36 h. These results highlight the need for more studies that describe the alterations caused by microplastics at the molecular level. Additionally, it opens questions about the effects caused to aquatic fauna in environmental realistic situations, especially in hot spots of microplastic contamination (e.g., tire rubber released in storm water runoff discharge points).


Assuntos
Chironomidae , Poluentes Químicos da Água , Animais , Chironomidae/genética , Expressão Gênica , Microplásticos , Plásticos/toxicidade , Poliestirenos , Borracha/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
19.
Environ Pollut ; 285: 117486, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34098457

RESUMO

Infection caused by pathogenic bacteria carrying antibiotic resistance genes (ARGs) is a serious challenge to human health. Water environment, including water and surface sediments, is an important repository of ARGs, and the activity of aquatic animal can affect the development of ARG pollution in the water environment. Macrobenthic invertebrates are an important component of aquatic ecosystems, and their effects on ARG development in aquatic environments remain unreported. The distribution of ARGs, including tetA gene, sul2 gene, and kan gene, in Chironomidae larvae is demonstrated in this study for the first time. The ARG distribution was related to sampling points, metal elements, and seasons. Animal models demonstrated that Chironomidae larvae enriched ARGs from water and passed them on to downstream predators in the food chain. Conjugative transfer mediated by resistant plasmids was crucial in the spread of ARG in Chironomidae larvae, and upregulated expression of trfAp gene and trbBp gene was the molecular mechanism. Escherichia in Proteobacteria and Flavobacterium in Bacteroidetes, which are gram-negative bacteria in Chironomidae larvae, are the primary host bacteria of ARGs confirmed via resistance screening and DNA sequencing of V4 region of 16S rRNA gene. Feeding experiments further confirmed that ARGs from Chironomidae larvae can be enriched in the fish gut. Research gaps in food chain between sediments and fish are addressed in this study, and Chironomidae larvae is an important enricher of ARGs in the freshwater environment.


Assuntos
Antibacterianos , Chironomidae , Animais , Antibacterianos/farmacologia , Chironomidae/genética , Resistência Microbiana a Medicamentos/genética , Ecossistema , Cadeia Alimentar , Água Doce , Genes Bacterianos , Humanos , Larva , RNA Ribossômico 16S
20.
Sci Total Environ ; 783: 146981, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34088153

RESUMO

Freshwater riverbeds are a major repository of microplastics (MPs) from inland activities. Benthic macroinvertebrates that live in close contact with sediments seem to ingest a considerable amount of such plastic particles. The effects of MPs on life-history traits are relatively well-known, but the suborganismal mechanisms underlying such effects remain unclear. This study addressed the potential effects of low-density polyethylene (LDPE) MPs on Chironomus riparius larvae at cellular and molecular levels. Fourth instar C. riparius larvae were exposed to 0.025 and 2.5 g/kg LDPE of dry sediment (sizes: <32 and 32-45 µm; with irregular shape) under laboratory conditions for 48 h. These short-term exposures to environmental concentrations of LDPE MPs induced changes in the energy reserves (mostly by decreasing carbohydrates and increasing lipids), increased antioxidant and detoxification responses (tGSH, CAT, and GST), and induced increases in the activity of AChE (related to neurotransmission). In addition, at the gene level, exposure to MPs modified mRNA levels of InR, Dis, EcR, Dronc, Met (endocrine system), Def (immune system), PARP, ATM, NLK, and Decay (DNA repair), generating important alterations in the C. riparius development and response to unfavorable situations. This study provides new evidence of the effects of LDPE MPs at the suborganismal level, filling the gap in knowledge regarding the mechanisms underlying the toxicity of MPs and spotlighting gene expression analyses as early indicators of MP toxicity in C. riparius which were confirmed by Integrated biomarker response analyses highlighting the gene expression as sensible and useful endpoints for LPDE pollution in freshwaters. These results, coupled with previous investigations on responses at the organismal level, emphasizes the potential adverse effects of LDPE MPs on C. riparius, which may compromise freshwater benthic communities, considering its ecological role within these habitats.


Assuntos
Chironomidae , Poluentes Químicos da Água , Animais , Larva , Microplásticos , Plásticos/toxicidade , Polietileno/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
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