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1.
Nature ; 577(7789): 226-230, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31853064

RESUMO

Predator-prey cycles rank among the most fundamental concepts in ecology, are predicted by the simplest ecological models and enable, theoretically, the indefinite persistence of predator and prey1-4. However, it remains an open question for how long cyclic dynamics can be self-sustained in real communities. Field observations have been restricted to a few cycle periods5-8 and experimental studies indicate that oscillations may be short-lived without external stabilizing factors9-19. Here we performed microcosm experiments with a planktonic predator-prey system and repeatedly observed oscillatory time series of unprecedented length that persisted for up to around 50 cycles or approximately 300 predator generations. The dominant type of dynamics was characterized by regular, coherent oscillations with a nearly constant predator-prey phase difference. Despite constant experimental conditions, we also observed shorter episodes of irregular, non-coherent oscillations without any significant phase relationship. However, the predator-prey system showed a strong tendency to return to the dominant dynamical regime with a defined phase relationship. A mathematical model suggests that stochasticity is probably responsible for the reversible shift from coherent to non-coherent oscillations, a notion that was supported by experiments with external forcing by pulsed nutrient supply. Our findings empirically demonstrate the potential for infinite persistence of predator and prey populations in a cyclic dynamic regime that shows resilience in the presence of stochastic events.


Assuntos
Clorófitas/fisiologia , Cadeia Alimentar , Modelos Biológicos , Rotíferos/fisiologia , Animais , Biota , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/fisiologia , Clorófitas/crescimento & desenvolvimento , Rotíferos/crescimento & desenvolvimento
2.
Sci Total Environ ; 688: 1348-1358, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726564

RESUMO

Proliferating cyanobacterial blooms due eutrophication in reservoirs is a major global problem. The production of cyanotoxins often increases with grazing pressure and temperature while the sensitivity of zooplankton to cyanotoxins is directly related to temperature. Here we evaluate the effect of different concentrations of the crude extract of cyanobacteria from Valle de Bravo reservoir during dry (January) and rainy (September) seasons at 20 and 25 °C on the rotifer Brachionus calyciflorus based on acute and chronic toxicity tests. We filtered 20 or 150 l of lake water, depending on the intensity of the bloom, and estimated the density and diversity of the cyanobacteria. The crude extracts, after 5 cycles of freezing, thawing and sonication at 14 MHz, were filtered and the microcystin concentration quantified based on ELISA. The extracts were used to conduct the acute and chronic toxicity tests, all in quadruplicate. Acute toxicity tests were based on 24 h mortality. Chronic toxicity tests (population growth and life table experiments) were conducted at 5 and 10% of the median lethal concentration. The field samples were dominated by Microcystis sp. (January) or Woronichinia naegeliana (September). The microcystin concentration in lake water was 9.57 µg/l and 0.097 µg/l and the median lethal concentration was 5.34 µg microcystin/L and 0.35 µg microcystin/L in January and September, respectively. Survival and reproduction of B. calyciflorus were lower in the presence of the cyanobacteria crude extract, more so at 20° than at 25 °C. Our results highlight the urgency of regular monitoring based on zooplankton assays for reservoirs in tropical and temperate regions, subject to frequent and dominant cyanobacterial blooms, often as a result of climate change.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental , Proliferação Nociva de Algas , Microcistinas/toxicidade , Rotíferos/fisiologia , Animais , Eutrofização , México , Testes de Toxicidade Crônica
3.
Ecotoxicology ; 28(6): 643-649, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31197615

RESUMO

Monogonont rotifers constitute, depending on the moment of the year, most of the zooplankton in many freshwater ecosystems. Sexual reproduction is essential in the development cycle of these organisms as it enables them to constitute stocks of cysts which can withstand adverse environmental conditions and hatch when favorable conditions return. However, endocrine disrupting compounds (EDCs) can interfere with the reproduction of organisms. The present work aimed to investigate the effects of cyproterone acetate (CPA, anti-androgen and progestogen synthetic steroid) at 0.5 mg L-1, on the sexual reproduction of Brachionus calyciflorus in a cross-mating experiment. Results show no impact on mixis whereas the fertilization rate and resting egg production were higher in females exposed to CPA (from embryogenesis to adult stage), regardless of the treatment applied to the males with which they were mating (i.e. males hatched from CPA-treated females or from control females). Moreover, neonate females which mothers has been exposed to 0.5 mg L-1 CPA had more oocytes in their germarium than control neonates. Our results suggest that the effects of CPA observed are not related to toxicity but rather are consistent with an endocrine disruption-related impact, probably through disturbance of the mate recognition protein (MRP) production and through interference with a steroid receptor. Moreover, the absence of effect on mixis rate indicates that mixis induction on the one hand and mating process and resting production on the other hand are not controlled by the same hormonal pathways.


Assuntos
Antagonistas de Androgênios/toxicidade , Acetato de Ciproterona/toxicidade , Disruptores Endócrinos/toxicidade , Rotíferos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Feminino , Reprodução/efeitos dos fármacos , Rotíferos/fisiologia , Zooplâncton/efeitos dos fármacos
4.
Molecules ; 24(11)2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31185582

RESUMO

The in vivo investigation of kynurenic acid (KYNA) and its analogs is one of the recent exciting topics in pharmacology. In the current study we assessed the biological effects of these molecules on bdelloid rotifers (Philodina acuticornis and Adineta vaga) by monitoring changes in their survival and phenotypical characteristics. In addition to longitudinal (slowly changing) markers (survival, number of rotifers alive and body size index), some dynamic (quickly responding) ones (cellular reduction capacity and mastax contraction frequency) were measured as well. KYNA and its analogs increased longevity, reproduction and growth, whereas reduction capacity and energy-dependent muscular activity decreased conversely. We found that spermidine, a calorie restriction mimetic, exerted similar changes in the applied micro-invertebrates. This characterized systemic profile evoked by the above-mentioned compounds was named beneficial physiologic attenuation. In reference experiments, using a stimulator (cyclic adenosine monophosphate) and a toxin (sodium azide), all parameters changed in the same direction (positively or negatively, respectively), as expected. The currently described adaptive phenomenon in bdelloid rotifers may provide holistic perspectives in translational research.


Assuntos
Ácido Cinurênico/análogos & derivados , Ácido Cinurênico/farmacologia , Rotíferos/fisiologia , Animais , Cinética , Ácido Cinurênico/química , Rotíferos/efeitos dos fármacos , Análise de Sobrevida
5.
Zoolog Sci ; 36(1): 52-57, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31116538

RESUMO

The cosmopolitan littoral rotifer Euchlanis dilatata is a potential model species in eco-toxicological and ecological studies, owing to its unique characteristics, such as periphytic benthic living, sensitivity to toxicity, and laying eggs on substrates instead of carrying them on the mother's body. However, studies about the life history strategy of this species, in contrast to the intensely studied planktonic Brachionus species, are relatively scarce. Temperature is an important factor that affects the rotifer's life history traits, and is well known to induce phenotypic plasticity in planktonic rotifers. The present study measured life table parameters of the rotifer E. dilatata originating from one clonal population local to Beijing under three temperature treatments: 14°C, 20°C and 26°C (10 females/replicate × 4 replicates for each treatment). We also examined trade-offs between egg size and egg number, as well as current reproduction and future survival to evaluate the life history strategy of the rotifer. In contrast to cold conditions, in which mothers produced a few large eggs with similar egg sizes, in warm environments, mothers produced many smaller eggs and a few larger eggs, thus resulting in a clear variation in egg sizes. With increasing temperature, the pre-mature period, reproductive period, life span and generation time shortened, while the net reproductive rate and population growth rate increased. Temperature also affected the trade-off between current reproduction and future survival. This work provides basic data for the potential model species E. dilatata.


Assuntos
Traços de História de Vida , Rotíferos/fisiologia , Temperatura , Animais , Tamanho da Ninhada , Feminino , Óvulo , Reprodução/fisiologia
6.
Artigo em Inglês | MEDLINE | ID: mdl-30884356

RESUMO

To understand the lipid metabolism in invertebrate species, identification of the fatty acid (FA) synthesis gene families in invertebrate species is important, since some FA are unable to be synthesized in the organisms by themselves. In the study, to identify the elongation of very long chain fatty acid (Elovl) genes in the marine rotifer Brachionus koreanus, the genome-wide identification and phylogenetic analysis of Elovl genes have been conducted with the expression profile of Elovl genes on the alga Tetraslemis suecica-fed B. koreanus. A total 10 Elovl genes have been identified from the genome of B. koreanus, with conserved HXXHH motif. Synteny analysis showed that tandem duplication event has occurred (Elovl3/6a and b, Elovl9a and b, and Elovl9c and d) in the ancestor. Phylogenetic analysis have clearly revealed that Brachionus spp. has only 2/5 and 3/6 subfamilies, and two novel Elovl classes have been revealed, namely Elovl9 and 10. Transcriptional data showed that the 10 Elovl genes were differently expressed and their expression could be regulated by feeding the alga T. suecica. From fatty acid (FA) profile data of the alga Tetraslemis suecica-fed B. koreanus, we revealed that the marine rotifer B. koreanus may synthesize very long chain fatty acid (VLCFA; >22 carbons) by themselves, as VLCFA was hardly detected in the alga T. suecica. The study provides a better understanding of FA metabolism of the marine rotifer B. koreanus after feeding the T. suecica.


Assuntos
Ácidos Graxos/genética , Rotíferos/genética , Transcriptoma , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Clorófitas/metabolismo , Ácidos Graxos/metabolismo , Filogenia , Rotíferos/fisiologia
7.
Environ Sci Pollut Res Int ; 26(12): 11793-11804, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30815809

RESUMO

Cyanobacterial blooms in eutrophic water bodies are a worldwide problem. Combined effects of mixtures of secondary metabolites produced by different cyanobacterial species on aquatic fauna are still not well recognised. We compared the survivorship of Brachionus calyciflorus Pallas (Rotifera) and Daphnia pulex Leyding (Cladocera) exposed to pure microcystin LR (MC-LR), anatoxin-a (ANTX) and to five extracts obtained from bloom-forming cyanobacteria Microcystis, Planktothrix and Dolichospermum. The obtained results revealed different response of the organisms to high concentrations of pure MC-LR, ANTX and complex cyanobacterial extracts. The extracts' toxicity to invertebrates was higher than that exerted by pure cyanotoxins and was dependent on the composition of cyanobacterial metabolites: Microcystis spp. extract containing anabaenopeptins A and B, aeruginosamide, four variants of cyanopeptolins and five MCs was not toxic to either of the organisms, whereas Planktothrix agardhii extract (I), containing anabaenopeptins A, B, F, 915, oscillamide Y, five different aeruginosins and four variants of MC was more toxic to daphnids than to rotifers. The extracts of another P. agarhdii (II) biomass and two different biomass samples of Dolichospermum spp. also affected survivorship of the rotifer and cladoceran, however, to various extent. It strongly suggests that non-ribosomal oligopeptides, other than MCs, had essential contribution to the observed toxicity to invertebrates and their effects on particular species or populations can vary depending on the secondary metabolite profiles of cyanobacteria.


Assuntos
Cianobactérias/metabolismo , Daphnia/fisiologia , Monitoramento Ambiental , Rotíferos/fisiologia , Animais , Daphnia/efeitos dos fármacos , Cadeia Alimentar , Água Doce , Microcistinas , Microcystis/metabolismo , Peptídeos Cíclicos , Rotíferos/efeitos dos fármacos , Tropanos
8.
BMC Ecol ; 19(1): 7, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30709393

RESUMO

BACKGROUND: A proposed mediator of trade-offs between survival and reproduction is oxidative stress resistance. Investments in reproduction are associated with increased oxidative stress that reduces lifespan. We used the bdelloid rotifer Adineta vaga to examine baseline patterns of survival, reproduction, and measures of oxidative stress, as well as how these patterns change in the face of treatments known to induce oxidative stress. RESULTS: We discovered that under standard laboratory conditions late-life mortality may be explained by increased levels of oxidative stress induced by reproduction. However, following exposure to the oxidizing agent ionizing radiation, survival was unaffected while reproduction was reduced. CONCLUSIONS: We suggest that under normal environmental conditions, reduced survival is mediated by endogenously generated oxidative stress induced by reproduction, and thus represents a cost of reproduction. Alternatively, the reduced reproduction evident under exogenously applied oxidative stress represents a cost of somatic maintenance. Biochemical analyses designed to assess levels of oxidative stress, oxidative stress resistance, and oxidative damage under normal and oxidizing conditions suggest that varying investments in enzymatic and non-enzymatic based oxidative stress resistance determine whether a cost of reproduction or a cost of somatic maintenance is observed.


Assuntos
Estresse Oxidativo , Rotíferos/fisiologia , Animais , Longevidade , Reprodução
9.
Aquat Toxicol ; 208: 39-46, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30605868

RESUMO

Although many efforts have been made to understand the toxic effects of metals in aquatic invertebrates, there are limited data regarding metal toxicity in natural ecosystems, as most previous studies were conducted under controlled laboratory conditions. To address this data gap, we analyzed toxic effects and molecular responses in the marine rotifer Brachionus koreanus and the marine copepod Tigriopus japonicus following in vivo exposure to a seawater sample collected from a polluted region in South Korea. Inductively coupled plasma-mass spectrometry (ICP-MS) analysis of the field seawater sample found a variety of metals. Exposure to several dilutions of the field seawater sample impacted several endpoints in both species, including mortality and reproduction. Interestingly, the rotifer and copepod test species exhibited different patterns of effects on reactive oxygen species (ROS) and antioxidant enzymatic activities, suggesting that different regulatory mechanisms may be activated in the two species in response to exposure to toxic chemicals. Our study helps to better understand the defense mechanisms activated in aquatic invertebrates in response to metal-induced oxidative stress induced by contaminated seawater.


Assuntos
Copépodes/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Rotíferos/fisiologia , Água do Mar/química , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Copépodes/efeitos dos fármacos , Copépodes/enzimologia , Copépodes/genética , Determinação de Ponto Final , Poluição Ambiental , Espécies Reativas de Oxigênio/metabolismo , Reprodução/efeitos dos fármacos , República da Coreia , Rotíferos/efeitos dos fármacos , Rotíferos/enzimologia , Rotíferos/genética , Testes de Toxicidade Aguda , Transcrição Genética/efeitos dos fármacos
10.
J Gerontol A Biol Sci Med Sci ; 74(6): 811-814, 2019 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-30165673

RESUMO

Rotifers are microinvertebrate models to study the phylogenetically based mechanisms of aging. Our study aimed to develop a physiological system with electron deprivation via a chemical electron carrier/acceptor pair together with extreme caloric restriction (ECR). Middle-aged Philodina acuticornis rotifers were treated with combinations of phenazine methosulfate (PMS, electron carrier) and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT, electron acceptor) for a period of 72 hours under total food deprivation (preselection). The ability of XTT to be reduced was confirmed both in vitro (with NADH) and in vivo (with live rotifers). Subsequently, the respective electron acceptor alone at a lower dose was administered in combination with ECR for several months on preselected survivors. We found that the longevity of rotifers markedly increased (4×) after PMS/XTT/total food deprivation preselection followed by XTT/ECR treatment. Ascorbic acid in equivalent concentrations caused similar but less pronounced tendencies. The synergistic effect of chemical electron deprivation and ECR caused delayed aging and the development of an outstanding phenotype that we refer to as "super rotifers," characterized by increased longevity and retained reproductive ability compared with normal middle-aged individuals. The presented model provides new insights into the connection between redox modulation and age-related features in vivo.


Assuntos
Restrição Calórica , Longevidade/fisiologia , Oxirredução , Rotíferos/fisiologia , Animais , Privação de Alimentos , Indicadores e Reagentes , Metilfenazônio Metossulfato , Modelos Animais , Sais de Tetrazólio
11.
Parasitology ; 146(1): 105-111, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29898802

RESUMO

Removal of parasite free-living stages by predators has previously been suggested an important factor controlling parasite transmission in aquatic habitats. Experimental studies of zooplankton predation on macroparasite larvae are, however, scarce. We tested whether trematode cercariae, which are often numerous in shallow waters, are suitable prey for syntopic zooplankters. Feeding rates and survival of freshwater cyclopoids (Megacyclops viridis, Macrocyclops distinctus), calanoids (Arctodiaptomus paulseni), cladocerans (Sida crystallina) and rotifers Asplanchna spp., fed with cercariae of Diplostomum pseudospathaceum, a common fish trematode, were studied. In additional long-term experiments, we studied reproduction of cyclopoids fed with cercariae. All tested zooplankton species consumed cercariae. The highest feeding rates were observed for cyclopoids (33 ± 12 cercariae ind-1 h-1), which actively reproduced (up to one egg clutch day-1) when fed ad libitum with cercariae. Their reproductive characteristics did not change significantly with time, indicating that cercariae supported cyclopoids' dietary needs. Mortality of rotifers and cladocerans was high (25-28% individuals) when exposed to cercariae in contrast to cyclopoids and calanoids (<2%). Cercariae clogged the filtration apparatus of cladocerans and caused internal injuries in predatory rotifers, which ingested cercariae. Observed trophic links between common freshwater zooplankters and cercariae may significantly influence food webs and parasite transmission in lentic ecosystems.


Assuntos
Comportamento Predatório/fisiologia , Trematódeos/crescimento & desenvolvimento , Zooplâncton/fisiologia , Análise de Variância , Animais , Cercárias , Copépodes/fisiologia , Cadeia Alimentar , Rotíferos/fisiologia , Caramujos/parasitologia
12.
Chemosphere ; 220: 146-154, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30583206

RESUMO

Many studies investigated the effects of environmental endocrine disruptors with the rotifer Brachionus calyciflorus. However, they focused on the reproductive behavior of rotifers, especially male-female fertilization, as a parameter in ecotoxicological and endocrine studies. In the present study, we used two environmental hormones (progesterone and testosterone) and one nonsteroidal antiandrogen (flutamide) at five different concentrations (0.5, 1, 2, 4, and 6 mg/L) to study the reproductive behavioral parameters of male rotifers. The average swimming speed of male rotifers in the blank group was 1.14 ±â€¯0.43 mm/s. After exposure for 1 h, testosterone improved the swimming speed of males, with the greatest effect at a concentration of 2-4 mg/L, whereas flutamide and progesterone inhibited the swimming speed. Copulatory behavior experiments showed that, compared with the control group, the recognition ability of males was improved by testosterone at 1, 2, and 3 h (P < 0.05). After 4, 5, and 6 h, progesterone substantially suppressed the mating recognition ability of males, where the density of each group was extremely low at 6 h. Flutamide had a similar effect on the mating recognition ability of male rotifers as that of progesterone. The male fertilization rate in B. calyciflorus increased significantly under testosterone exposure at different concentrations (P < 0.05), with the highest level at 2 mg/L (male fertility rate = 48.61 ±â€¯3.18%). The fertilization rate of male rotifers was suppressed by both progesterone and flutamide (P < 0.05), and higher drug concentrations had stronger suppressive effects.


Assuntos
Fertilidade/efeitos dos fármacos , Rotíferos/efeitos dos fármacos , Poluentes Químicos da Água/farmacologia , Animais , Flutamida/farmacologia , Masculino , Progesterona/farmacologia , Reprodução/efeitos dos fármacos , Rotíferos/fisiologia , Natação , Testosterona/farmacologia
13.
Ying Yong Sheng Tai Xue Bao ; 29(12): 4208-4216, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30584750

RESUMO

To understand the effects of macrophyte growth on water environment and rotifer community structure, monthly survey lasted for one year from October 2015 to September 2016 was conducted in Lake Minghu and Lake Nanhu at Jinan University in Guangzhou. There was no macrophyte cultivation in Lake Minghu. A kind of macrophyte Hydrilla verticillata grows from March-October in Lake Nanhu and grows vigorously in June-September. In this study, 50 species belonging to 23 gene-ra of rotifer, were recorded in the two lakes. 32 species were found in Lake Minghu and 39 species in Lake Nanhu, respectively. The dominant species in Lake Minghu were Polyarthra vulgaris, Trichocerca pusilla and Liliferotrocha subtilis. The dominant species in Lake Nanhu were Keratella cochlearis, Colurella adriatica and Lecane (Monostyla) bulla. The highest abundance of rotifers in Lake Minghu was at 3790 ind·L-1 in October 2015, and the lowest at 854 ind·L-1 in March 2016. The highest abundance of rotifers in Lake Nanhu was at 3555 ind·L-1 in November 2015, and the lowest at 977 ind·L-1 in January 2016. Results from the ANOSIM (one-way) test revealed that the community structure of rotifers was significantly different between Lake Minghu and Lake Nanhu. The largest contribution rate of the difference between the two lakes was made by Keratella cochlearis and Polyarthra vulgaris. RDA analysis showed that total phosphorus, chlorophyll a, and water temperature had significant impacts on the community structure of rotifer in Lake Minghu. During the period with luxuriant macrophyte in Lake Nanhu, the rotifer community structure was most influenced by total phosphorus, water temperature, chlorophyll a and water depth, dominated by benthic species Squatinella mutica, Colurella adriatica and Lecane bulla. During the period with sparse macrophyte, the community was mainly influenced by total nitrogen and transparency, dominanted by planktonic species Polyarthra vulgaris and Trichocerca similis. During the period with no macrophyte, communities were mainly influenced by pH and dissolved oxygen, and also dominated by planktonic ones Polyarthra vulgaris and Anuraeopsis fissa. Macrophyte could effectively absorb nutrients in water, inhibit growth of phytoplankton, improve water quality, increase spatial heterogeneity, support more species of rotifer, and maintain a stable aquatic ecosystem.


Assuntos
Agricultura/métodos , Organismos Aquáticos/fisiologia , Ecossistema , Rotíferos/fisiologia , Animais , Clorofila A/metabolismo , Lagos , Plâncton
14.
Biol Lett ; 14(11)2018 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-30487258

RESUMO

Under global warming scenarios, rising temperatures can constitute heat stress to which species may respond differentially. Within a described species, knowledge on cryptic diversity is of further relevance, as different lineages/cryptic species may respond differentially to environmental change. The Brachionus calyciflorus species complex (Rotifera), which was recently described using integrative taxonomy, is an essential component of aquatic ecosystems. Here, we tested the hypothesis that these (formerly cryptic) species differ in their heat tolerance. We assigned 47 clones with nuclear ITS1 (nuITS1) and mitochondrial COI (mtCOI) markers to evolutionary lineages, now named B. calyciflorus sensu stricto (s.s.) and B. fernandoi We selected 15 representative clones and assessed their heat tolerance as a bi-dimensional phenotypic trait affected by both the intensity and duration of heat stress. We found two distinct groups, with B. calyciflorus s.s. clones having higher heat tolerance than the novel species B. fernandoi This apparent temperature specialization among former cryptic species underscores the necessity of a sound species delimitation and assignment, when organismal responses to environmental changes are investigated.


Assuntos
Evolução Biológica , Temperatura Alta/efeitos adversos , Rotíferos/fisiologia , Animais , Filogenia , Especificidade da Espécie , Estresse Fisiológico
15.
Exp Gerontol ; 114: 99-106, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30399408

RESUMO

Lifespan extension under low temperature is well conserved across both endothermic and exothermic taxa, but the mechanism underlying this change in aging is poorly understood. Low temperature is thought to decrease metabolic rate, thus slowing the accumulation of cellular damage from reactive oxygen species, although recent evidence suggests involvement of specific cold-sensing biochemical pathways. We tested the effect of low temperature on aging in 11 strains of Brachionus rotifers, with the hypothesis that if the mechanism of lifespan extension is purely thermodynamic, all strains should have a similar increase in lifespan. We found differences in change in median lifespan ranging from a 6% decrease to a 100% increase, as well as differences in maximum and relative lifespan extension and in mortality rate. Low temperature delays reproductive senescence in most strains, suggesting an extension of healthspan, even in strains with little to no change in lifespan. The combination of low temperature and caloric restriction in one strain resulted in an additive lifespan increase, indicating these interventions may work via non- or partially-overlapping pathways. The known low temperature sensor TRPA1 is present in the rotifer genome, but chemical TRPA1 agonists did not affect lifespan, suggesting that this gene may be involved in low temperature sensation but not in chemoreception in rotifers. The congeneric variability in response to low temperature suggests that the mechanism of low temperature lifespan extension is an active genetic process rather than a passive thermodynamic one and is dependent upon genotype.


Assuntos
Temperatura Baixa , Longevidade , Rotíferos/genética , Rotíferos/fisiologia , Animais , Restrição Calórica , Regulação da Expressão Gênica , Espécies Reativas de Oxigênio/metabolismo , Reprodução , Canal de Cátion TRPA1/genética
16.
Toxins (Basel) ; 10(11)2018 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-30380633

RESUMO

The toxic effects of the typically noxious bloom-forming dinoflagellate Karenia mikimotoi were studied using the allelopathic experimental system under controlled laboratory conditions. The potency of intact cell suspensions with whole cells, cell-free culture filtrate in different growth phases, and lysed cells with ultrasonication were compared, and the growth and reproduction of the marine rotifer Brachionus plicatilis were used as endpoints to evaluate toxic differences. The intact cell suspension resulted the most significant growth inhibition, including lethality, on the growth of B. plicatilis (p < 0.05). Lysed culture medium treated with ultrasonication and the cell-free culture filtrates at either the exponential or stationary phase exhibited limited negative impacts compared to the control according to changes in the population growth rate (r) and survival rate (p > 0.05). Reproduction presented a similar tendency to change, and the number of eggs produced per individual, as well as spawning period decreased in the whole cell and lysed cell suspensions. The key parameters in the lift table include the net reproductive rate (R0) and the intrinsic rate of increase (rm), which were more sensitive to treatment and were significantly suppressed compared to that of the control. The addition of the ROS inhibitor N-acetylcysteine (NAC) could not change the growth or reproduction patterns. Moreover, substantial hemolytic toxicity was found in the treatment of the intact cell suspension (p < 0.05), while limited toxicity was found in other treatments compared to that of the control. K. mikimotoi was speculated to secrete allelopathic substances onto the cell surface, and direct cell contact was necessary for allelopathic toxicity in B. plicatilis. Reactive oxygen species (ROS)-independent hemolytic toxicity was assumed to be the explanation for what was observed.


Assuntos
Alelopatia , Dinoflagelados/metabolismo , Hemólise , Rotíferos/fisiologia , Animais , Proliferação Nociva de Algas , Espécies Reativas de Oxigênio/metabolismo , Reprodução
17.
Sci Rep ; 8(1): 16051, 2018 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30375419

RESUMO

Environmental fluctuations are ubiquitous and thus essential for the study of adaptation. Despite this, genome evolution in response to environmental fluctuations -and more specifically to the degree of environmental predictability- is still unknown. Saline lakes in the Mediterranean region are remarkably diverse in their ecological conditions, which can lead to divergent local adaptation patterns in the inhabiting aquatic organisms. The facultatively sexual rotifer Brachionus plicatilis shows diverging local adaptation in its life-history traits in relation to estimated environmental predictability in its habitats. Here, we used an integrative approach -combining environmental, phenotypic and genomic data for the same populations- to understand the genomic basis of this diverging adaptation. Firstly, a novel draft genome for B. plicatilis was assembled. Then, genome-wide polymorphisms were studied using genotyping by sequencing on 270 clones from nine populations in eastern Spain. As a result, 4,543 high-quality SNPs were identified and genotyped. More than 90 SNPs were found to be putatively under selection with signatures of diversifying and balancing selection. Over 140 SNPs were correlated with environmental or phenotypic variables revealing signatures of local adaptation, including environmental predictability. Putative functions were associated to most of these SNPs, since they were located within annotated genes. Our results reveal associations between genomic variation and the degree of environmental predictability, providing genomic evidence of adaptation to local conditions in natural rotifer populations.


Assuntos
Adaptação Fisiológica/genética , Genômica , Rotíferos/genética , Seleção Genética , Aclimatação , Animais , Ecossistema , Meio Ambiente , Genoma/genética , Genótipo , Região do Mediterrâneo , Polimorfismo de Nucleotídeo Único/genética , Rotíferos/fisiologia , Espanha
18.
Mar Environ Res ; 139: 193-200, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29804787

RESUMO

Treatment of dredged materials is a critical issue, since management and disposal of these products requires considerable investment of monetary resources, time, and space. The high concentration of pollutants in dredged materials, along with high water content and many fine particles make recycling these materials particularly difficult. In order to solve this problem, solidification/stabilization has been considered as a potentially viable solution for recycling dredged marine sediments. However, there are currently no guidelines that address potential biological and environmental impacts. To evaluate the stability of treated materials and their biological impacts, dredged marine sediments, which were polluted with heavy metals, were treated by solidification/stabilization using two different solidifying agents. To assess potential impacts, toxicity characteristic leaching procedures (TCLP, USEPA) and a bioassay (with the rotifer, Brachionus sp.) were performed with treated materials. In a TCLP test, we found that treatment with a solidification agent decreased the leaching concentration of heavy metals from sediment compared to the control. The rotifer bioassay showed no change in the survival rate during 24 h of exposure to both agents. However, survival differed between the two agents after 48 h of exposure. Screening physiological status using gene expression, showed that oxidative stress genes were significantly altered. These results suggest that more studies are needed to provide guidelines for deciding the usability of treated materials created by the solidification or stabilization of dredged materials.


Assuntos
Monitoramento Ambiental/métodos , Recuperação e Remediação Ambiental/métodos , Metais Pesados/análise , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental/normas , Sedimentos Geológicos/química , Rotíferos/fisiologia
19.
An Acad Bras Cienc ; 90(2): 1431-1444, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29768573

RESUMO

In the present work, we provide the first approach about the life-history of Brachionus plicatilis in South America. We tested with laboratory experiments the response of the pampean strain of B. plicatilis for two of its main stressors (conductivity and temperature). We evaluated the effects of eight conductivity values from 1 to 17 mS.cm-1 and two temperatures (15 and 25 °C) to compare its abundance with those obtained in the pampean lotic and lentic environments, where this rotifer is frequent or dominant. The results demonstrated that the increase in population-growth rate and the peak of abundance occurred at the highest temperature and at medium conductivity. Minimum values were obtained at the lowest temperature and conductivities analyzed, but the final density attained was nevertheless similar to those recorded in the pampean environments at the optimum conductivity and during the spring and summer seasons. Males, mictic females, and resting eggs were observed at the minimum and maximum conductivities, revealing the strategy of this species for maintaining dominance in environments with fluctuating salinity. The experiments also indicated the possible behavior of this relevant member of the zooplankton community within a scenario of increasing temperature and salinity related to the climate changes occurring in the pampean region.


Assuntos
Rotíferos/fisiologia , Salinidade , Temperatura , Animais , Argentina , Feminino , Masculino , Densidade Demográfica , Reprodução/fisiologia , Rotíferos/crescimento & desenvolvimento , Estações do Ano
20.
Sci Rep ; 8(1): 6022, 2018 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-29662078

RESUMO

In rotifers, the costs of morphological defenses, especially the development of long spines, have been investigated for several decades. However, the obtained results were inconsistent and the underlying reasons were complicated. Investigations on more species might be helpful to find out the reasons. In the present study, Brachionus forficula was selected as the model organism. The differences in developmental durations, life-table demography, starvation resistant time and the competitive ability with Moina macrocopa were compared between B. forficula with long (LPS) and short (SPS) posterior spines. The results showed that LPS showed relatively longer durations of juvenile stage at 1.0 × 106, 2.0 × 106 and 4.0 × 106 cells/ml Scenedesmus obliquus, and longer embryo stage at 2.0 × 106 cells/ml S. obliquus than SPS. The intrinsic rate of population increase and net reproduction rate were lower in LPS than SPS, suggesting the energy input to reproduction decreased. The starvation resistant time was also reduced in LPS, in comparison to SPS, further supporting that LPS consumed more energy, which might be directed to the development of long spines. All these results revealed that LPS spent more energy for individual growth than SPS, which might be used to develop long spines. Moreover, the maximum population density and population growth rate of LPS were always lower than those of SPS, suggesting that LPS might have a weaker competition ability with M. macrocope than SPS.


Assuntos
Rotíferos/crescimento & desenvolvimento , Animais , Comportamento Competitivo , Ingestão de Alimentos , Metabolismo Energético , Crescimento Demográfico , Reprodução , Rotíferos/anatomia & histologia , Rotíferos/fisiologia , Rotíferos/ultraestrutura
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