RESUMO
Habitat selection by aquatic organisms is dependent on the availability of adequate conditions to support life and the benefits that the habitat provides. Contaminated environments tend to be less attractive to organisms because reduced habitat quality leads to increased maintenance costs. Consequently, reduced colonization of such disturbed habitats is an expected response. However, colonization has been understudied as an ecotoxicological test endpoint, despite its proven ability to assess habitat selection by populations across various taxa. The aim of the present study was to investigate whether previous exposure to copper could alter the colonization behavior of the freshwater prawn Macrobrachium rosenbergii along a non-forced exposure gradient of interconnected copper-contaminated habitats (0 to 500 µg/L) due to physiological and behavioral impairments. To assess this, post-larvae of M. rosenbergii were pre-exposed to 0, 50, 250 and 500 µg/L copper for a maximum period of 48 h. The physiological status and motility of the organisms after pre-exposure to copper were evaluated using behavioral endpoints (swimming activity by video tracking) and biochemical biomarkers (biotransformation, oxidative stress and neurotoxicity). The results indicated that pre-exposure to copper (at concentrations of 0, 50 and 500 µg/L) significantly influenced the median colonization concentration (CC50), which decreased from 270 µg/L to 109 µg/L. None of the assessed swimming parameters (speed, motility rate, exploration rate, and total distance) were affected by the pre-exposure to copper (0, 50 and 250 µg/L). Biochemically, cholinesterase levels were only affected in the prawn population exposed to 250 µg/L of copper. The present study provides a better understanding of the relevance of colonization as an ecotoxicological endpoint for assessing the spatial distribution of populations, including both new inhabitants and previously exposed organisms, in recovering habitats.
Assuntos
Comportamento Animal , Cobre , Ecossistema , Palaemonidae , Poluentes Químicos da Água , Animais , Palaemonidae/efeitos dos fármacos , Palaemonidae/fisiologia , Cobre/toxicidade , Poluentes Químicos da Água/toxicidade , Comportamento Animal/efeitos dos fármacos , Biomarcadores , Estresse Oxidativo/efeitos dos fármacosRESUMO
Predation pressure influences animal behaviour in relation to feeding, exposure to predators and habitat use. In the presence of a predator, prey usually decreases feeding and activity, avoiding predation-risk areas. This study evaluated the visual effects of a predator fish (red-bellied piranha Pygocentrus nattereri) on the behaviour and habitat use of Macrobrachium jelskii prawn. It was hypothesized that prawns would modify their behaviour in the presence of a predator, decreasing their general activity (foraging and locomotion) and seeking shelter more frequently. Twenty behavioural tests were carried out without and with the presence of a predator using five different M. jelskii individuals per trial. Behavioural data were collected using scan sampling with instantaneous recording of behaviours every 15â¯s during 5â¯min in each trial. The presence of the predator caused prawns to decrease their locomotion and feeding and increase environment exploration and predator inspection. Prawns used the shelter more frequently when the predator was present. Red-bellied piranha elicited anti-predator behaviour in M. jelskii. The patterns observed suggested that the most common anti-predatory behaviours exhibited by M. jelskii are beneficial as they reduce vigilance and active anti-predation strategies, such as escape.
Assuntos
Comportamento Animal , Palaemonidae , Comportamento Predatório , Animais , Comportamento Predatório/fisiologia , Palaemonidae/fisiologia , Comportamento Animal/fisiologia , Ecossistema , Água Doce , Peixes/fisiologia , Comportamento Alimentar/fisiologia , Locomoção/fisiologiaRESUMO
Signal theory predicts organisms should evolve signals that are conspicuous to intended receivers in natural signalling environments. Cleaner shrimps remove ectoparasites from reef fish clients and many signal their intent to clean by whipping long, white antennae. As white is a reliably conspicuous colour in aquatic environments, we hypothesized that selection has acted to increase broad-spectrum antennal reflectance in cleaners. Using scanning electron microscopy, optical models and reflectance measurements, we found that the antennae in three obligate cleaner species from two families (Palaemonidae and Lysmatidae) had thick (â¼6â µm) chitinous layers or densely packed high refractive index spheres (300-400â nm diameter), which models show increase reflectance (400-700â nm). Two facultative and non-cleaning species had no visible antennae ultrastructure beyond the chitinous exoskeleton. Antennae reflectance was significantly higher in obligate cleaners than in facultative and non-cleaning species. Our results suggest that some obligate cleaners may have evolved ultrastructures that increase the conspicuousness of their antennae as signals.
Assuntos
Antenas de Artrópodes , Animais , Antenas de Artrópodes/ultraestrutura , Antenas de Artrópodes/fisiologia , Microscopia Eletrônica de Varredura , Palaemonidae/fisiologia , Palaemonidae/ultraestrutura , Palaemonidae/anatomia & histologia , Comunicação Animal , Decápodes/fisiologia , Decápodes/anatomia & histologia , Decápodes/ultraestruturaRESUMO
Despite the existing connectivity and heterogeneity of aquatic habitats, the concept of interconnected landscapes has been frequently overlooked in ecotoxicological risk assessment studies. In this study, a novel mesocosm system, the HeMHAS (Heterogeneous Multi-Habitat Assay System), was constructed with the potential to assess structural and functional changes in a community resulting from exposure to contaminants, while also considering the complex ecological scenarios. Fish (Sparus aurata), shrimp (Palaemon varians) and three species of marine microalgae (Isochrysis galbana, Nannochloropsis gaditana and Tetraselmis chuii) were used as test organisms. Other species, such as Artemia sp. and macroalgae were also introduced into the system as environmental enrichment. All the species were distributed in five interconnected mesocosm compartments containing a copper gradient (0, 1, 10, 100 and 250 µg/L). The mobile fish avoided the copper contaminants from 1 µg/L (24 h-AC50: 4.88 µg/L), while the shrimp avoided from 50 µg/L (24 h-AC50: 136.58 µg/L). This finding suggests interspecies interactions influence habitat selection in contaminated environments, potentially jeopardizing population persistence. Among the non-motile organisms, the growth and chlorophyll content of the microalgae were concentration dependent. The growth of I. galbana was more sensitive (growth inhibition of 50 % at the highest concentration) in contrast to N. gaditana (30 % inhibition at the highest concentration) and T. chuii (25 % inhibition at the last two highest concentrations). In summary, the mesocosm HeMHAS showed how contamination-driven responses can be studied at landscape scales, enhancing the ecological relevance of ecotoxicological research.
Assuntos
Microalgas , Poluentes Químicos da Água , Animais , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/análise , Microalgas/fisiologia , Ecossistema , Monitoramento Ambiental , Palaemonidae/fisiologia , Peixes/fisiologia , Ecotoxicologia , Estresse Fisiológico , Artemia , Medição de Risco , Cobre/toxicidadeRESUMO
Since 2000, a well-established population of the invasive oriental shrimp Palaemon macrodactylus has been present in fully marine conditions in the southwestern Atlantic Ocean (~38° S). To assess the physiological performance of this atypical population restricted to fully marine conditions, we conducted a laboratory experiment in which individuals were transferred from 35 S (local seawater) to 2 S; 5 S; 10 S; 20 S; 50 S and 60 for short (6 h), medium (48 h), and long (>504 h) acclimation periods. We measured the time course response of relevant parameters in the shrimp's hemolymph; activity of Na+, K+-ATPase (NKA), and V-H+-ATPase (VHA); and muscle water content. Shrimp showed great osmoregulatory plasticity, being able to survive for long periods between 5 S and 50 S, whereas no individual survived after transfer to either 2 S or 60 S. Shrimp hyper-regulated hemolymph osmolality at 5 S and 10 S, hypo-regulated at 35 S and 50 S, and isosmoticity was close to 20 S. Compared to 35 S, prolonged acclimation to 5 S caused a decrease in hemolymph osmolality (~34%) along with sodium and chloride concentrations (~24%); the NKA and VHA activities decreased by ~52% and ~88%, respectively, while muscle water content was tightly regulated. Our results showed that the atypical population of P. macrodactylus studied here lives in a chronic hypo-osmo-ion regulatory state and suggest that fully marine conditions contribute to its poor performance at the lower limit of salinity tolerance (<5 S).
Assuntos
Palaemonidae , Animais , Palaemonidae/fisiologia , Salinidade , Espécies Introduzidas , Hemolinfa/química , Aclimatação/fisiologia , Água do Mar/químicaRESUMO
Phenotypic links are the potential for "carryover" of effects of experience during one life history stage into performance and selection at subsequent stages. They reflect plastic responses to the environment experienced during an early phase on the phenotype of subsequent phases. We are studying these effects by following individuals of the shrimp Palaemon serratus from the embryonic (eggs carried by females) through the larval phase (pelagic) to the juvenile phase (benthic). In experiment 1, we investigated the effects of larval prey concentration (10, 4 and 2 Artemia/mL) and larval incubation temperature (16 and 22 °C) on larval performance (metamorphosis rate, developmental duration and growth) and then on juvenile performance (survival and Specific Growth Rate, SGR, at 18 and 24 °C in 14 days). In experiment 2, we investigated the effects of embryonic incubation temperature (larval biomass and lipid content of newly hatched larvae from embryos incubated at 12 and 18 °C) and larval prey concentration on larval performance and then on juvenile performance. In both experiments, the larvae plastically increased their development time in response to the reduction in temperature and prey concentration, whereas their survival decreased with temperature and prey concentration. The quantity of lipids available at hatching decreased with decreasing embryonic incubation temperature, which reduced the larval performance, particularly with a low concentration of prey. Survival at 14 days post-metamorphosis was significantly reduced when the embryos were incubated at 12 °C compared with those incubated at 18 °C, regardless of the subsequent larval incubation conditions, revealing phenotypic links between overconsumption of embryonic yolk reserves and post-metamorphic fitness. Overall, juveniles had a better SGR at 24 than at 18 °C, and even better when incubated under stressful embryo-larval conditions (temperature and prey concentration). This study highlighted phenotypic links between developmental stages and over developmental periods of several months.
Assuntos
Larva , Palaemonidae , Temperatura , Animais , Palaemonidae/crescimento & desenvolvimento , Palaemonidae/fisiologia , Larva/crescimento & desenvolvimento , Comportamento Alimentar , Embrião não Mamífero/fisiologia , Metabolismo dos Lipídeos , FemininoRESUMO
The hyperarid mangrove in the Middle East is characterised by the absence of rivers or freshwater inputs and is one of the most extreme settings of this ecosystem on Earth. Endemic to Qatar's hyperarid mangroves, a Palaemon shrimp is uniquely confined to a sole mangrove site in the Arabian Gulf. Within these mangrove channels, we unveiled brine groundwater sources exceeding 70 ppt salinity, contrasting the local marine standard of 42 ppt. Concurrently, a mysid species typically linked to salt pans and groundwater coexists. Stable isotopic analysis implied the existence of a predator-prey dynamic between this mysid species and the studied shrimp. Then, investigating the endemic shrimp's adaptation to extreme salinity, we conducted osmolarity experiments and phylogenetic studies. Our findings demonstrate that this shrimp transitions from hypo- to hyper-osmoregulation, tolerating salinities from 18 to 68 ppt-an unprecedented osmoregulatory capacity among caridean shrimps. This speciation pattern likely arises from the species osmolarity adaptation, as suggested for other Palaemon congeners. Phylogenetic analysis of the studied Palaemon, along with the mangrove's geological history, suggests a profound evolutionary interplay between the ecosystem and the shrimp since the Eocene. This study proposes the hyperarid mangrove enclave as an Athalassic mangrove oasis-a distinctive, isolated ecosystem within the desert landscape.
Assuntos
Osmorregulação , Palaemonidae , Animais , Ecossistema , Filogenia , Equilíbrio Hidroeletrolítico , Concentração Osmolar , Palaemonidae/fisiologiaRESUMO
Environmental stresses play critical roles in the physiology of crustaceans. Food deprivation is an important environmental factor and a regular occurrence in both natural aquatic habitats and artificial ponds. However, the underlying physiological response mechanisms to starvation-caused stress in crustaceans are yet to be established. In the present study, the hepatopancreas tissue of Macrobrachium nipponense was transcriptome analyzed and examined for starvation effects on oxidative stress, DNA damage, autophagy, and apoptosis across four fasting stages (0 (control group), 7, 14, and 21 days). These results indicated that a ROS-mediated regulatory mechanism is critical to the entire fasting process. At the initial stage of starvation (fasting 0 d ~ 7 d), ROS concentration increased gradually, activating antioxidant enzymes to protect the cellular machinery from the detrimental effects of oxidative stress triggered by starvation-induced stress. ROS content production (hydrogen peroxide and superoxide anion) then rose continuously with prolonged starvation (fasting 7 d ~ 14 d), reaching peak levels and resulting in autophagy in hepatopancreas cells. During the final stages of starvation (fasting 14 d ~ 21 d), excessive ROS induced DNA damage and cell apoptosis. Furthermore, autophagolysosomes and apoptosis body were further identified with transmission electron microscopy. These findings lay a foundation for further scrutiny of the molecular mechanisms combating starvation-generated stress in M. nipponense and provide fishermen with the theoretical guidance for adopting fasting strategies in M. nipponense aquaculture.
Assuntos
Autofagia , Hepatopâncreas , Estresse Oxidativo , Palaemonidae , Animais , Palaemonidae/fisiologia , Palaemonidae/genética , Palaemonidae/metabolismo , Hepatopâncreas/metabolismo , Dano ao DNA , Apoptose , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Inanição , Privação de Alimentos , TranscriptomaRESUMO
The germ cell-less gene is crucial for gonad development in various organisms. Early interventions in its expression suggested a regulatory role at the mitotic stages of spermatogenesis, and its early knockout resulted in complete sterility in Drosophila. Genomic and transcriptomic data available for the catadromous giant prawn Macrobrachium rosenbergii enabled the identification of a germ cell-less homolog for this species, which we termed MroGCL (mRNA accession number OQ533056). An open reading frame containing 494 amino acids and a typical evolutionarily conserved BTB/POZ domain suggests possible protein-protein interaction functions in keeping with the Drosophila germ cell-less protein. Genomic mapping of MroGCL showed a full length of 120 896 bases. Analysis of the temporal expression of MroGCL showed constant expression in early prawn embryonic and larval stages, but a significant increase 10 days after metamorphosis when crucial sexual differentiation processes occur in prawns. In adult animals, high expression was detected in the gonads compared to the somatic tissues. RNAi-based knock-down experiments showed that both the silenced and control groups reached advanced spermatogenic stages, but that there was a significant decrease in the yield of spermatozoa in about half of the silenced animals. This finding supports our hypothesis that MroGCL is crucial for mitosis during early stage spermatogenesis. In conclusion, this study contributes to the understanding of crustacean gonad development and provides a stepping stone in the development of environmentally valuable sterile crustacean populations.
Assuntos
Palaemonidae , Espermatogênese , Animais , Palaemonidae/genética , Palaemonidae/fisiologia , Espermatogênese/fisiologia , Espermatogênese/genética , Masculino , Sequência de Aminoácidos , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/metabolismoRESUMO
This study aimed to investigate the effects of replacing fishmeal (FM) with African giant snail (Achatina fulica) meal (SM) on the growth performance of giant river prawn (Macrobrachium rosenbergii), as well as to analyze the associated metabolomic changes. Six diets were formulated, replacing FM with SM at different inclusion levels ranging from 0 % to 100 %. Growth performance and feed conversion ratio of prawns fed diets with FM replaced by SM up to 80 % were not significantly different from control. In contrast, significantly decreased growth performance and higher feed conversion ratio (FCR) occurred with diets containing 100 % SM. To gain insights into the metabolic regulation of prawns fed different diets, a 1H NMR metabolomics approach was used to assess the metabolic changes in prawns fed diets containing 0 % and 80 % SM. The results revealed up-regulated metabolites significantly involved in several metabolic pathways, including alanine, aspartate, and glutamate metabolism; citrate cycle (TCA cycle); aminoacyl-tRNA biosynthesis; and valine, leucine, and isoleucine biosynthesis. These findings imply that including SM in the diet might modulate the regulation of muscle amino acids and tRNA synthesis, suggesting a potential impact on protein biosynthesis mechanisms. Additionally, alterations in the TCA cycle may reflect changes in carbon utilization, potentially contributing to the growth performance of giant river prawns when fishmeal is replaced with SM without adversely affecting their growth. In conclusion, this study demonstrated that SM could be a promising alternative protein source in aquafeed. The metabolomic approach provides valuable insights into the metabolic changes in prawns fed different diets, aiding in the development of more effective aquafeeds in the future. The study's limitations, such as the simplified diet formulation and the limited scope of the metabolomic analysis, were acknowledged and discussed, highlighting the need for further research to build upon these findings.
Assuntos
Palaemonidae , Animais , Palaemonidae/fisiologia , Dieta , Caramujos , RNA de TransferênciaRESUMO
Use of agrochemicals, including insecticides, is vital to food production and predicted to increase 2-5 fold by 2050. Previous studies have shown a positive association between agriculture and the human infectious disease schistosomiasis, which is problematic as this parasitic disease infects approximately 250 million people worldwide. Certain insecticides might runoff fields and be highly toxic to invertebrates, such as prawns in the genus Macrobrachium, that are biocontrol agents for snails that transmit the parasites causing schistosomiasis. We used a laboratory dose-response experiment and an observational field study to determine the relative toxicities of three pyrethroid (esfenvalerate, λ-cyhalothrin, and permethrin) and three organophosphate (chlorpyrifos, malathion, and terbufos) insecticides to Macrobrachium prawns. In the lab, pyrethroids were consistently several orders of magnitude more toxic than organophosphate insecticides, and more likely to runoff fields at lethal levels according to modeling data. At 31 water contact sites in the lower basin of the Senegal River where schistosomiasis is endemic, we found that Macrobrachium prawn survival was associated with pyrethroid but not organophosphate application rates to nearby crop fields after controlling for abiotic and prawn-level factors. Our laboratory and field results suggest that widely used pyrethroid insecticides can have strong non-target effects on Macrobrachium prawns that are biocontrol agents where 400 million people are at risk of human schistosomiasis. Understanding the ecotoxicology of high-risk insecticides may help improve human health in schistosomiasis-endemic regions undergoing agricultural expansion.
Assuntos
Clorpirifos , Inseticidas , Palaemonidae , Piretrinas , Esquistossomose , Animais , Humanos , Inseticidas/toxicidade , Piretrinas/toxicidade , Esquistossomose/epidemiologia , Esquistossomose/parasitologia , Permetrina , Palaemonidae/fisiologiaRESUMO
Prawns are regarded as delicious food items and a source of income as it is the salient exportable fishery item of Bangladesh and a number of other countries. Climate change may inhibit the general physiological activity of prawns. This study explored the eco-climatic effects on reproduction, including size at first sexual maturity (Lm), spawning season, and fecundity of monsoon river prawn, Macrobrachium malcolmsonii (Milne-Edwards, 1844). The study was carried out in the Ganges (Padma) River basin, northwestern Bangladesh, from January to December 2014. Seven hundred fifty-seven specimens ranging from 0.80 to 18.27 g BW (body weight) with TLs (total length) of 4.20 to 11.52 cm were analyzed. The Lm was estimated as 6.2-6.6 cm. Total fecundity was higher than earlier studies and ranged from 2743 to 122,165 with a mean value of 6715 ± 2437. The spawning season was estimated from April to October with a peak in July. Significant correlation was found between rainfall and the presence of ovigerous females, i.e., spawning season. The number of ovigerous females increased in ≥ 100 mm average rainfall, and the maximum ovigerous female spawned at 250-320 mm rainfall. Spawning season of M. malcolmsonii may have shifted with shifting rainy season as a result of climate change. The findings of our investigation would be useful for sustainable management of the fishery of M. malcolmsonii and other prawn species in the Ganges River, Bangladesh, and adjoining countries with similar eco-climatic factors.
Assuntos
Clima , Palaemonidae , Reprodução , Animais , Feminino , Peso Corporal , Água Doce , Palaemonidae/fisiologia , Reprodução/fisiologia , Rios , Estações do Ano , Bangladesh , ChuvaRESUMO
Pesticides containing diazinon are frequently used in agriculture in the Vietnamese Mekong delta region leading to their potential residual occurrence in the environment. Under laboratory conditions, exposure to diazinon has been shown to result in adverse inhibition of cholinesterase enzyme (ChE) activity and subsequent death in several fish species. This study investigated a 96-h median lethal concentration (LC50) of diazinon concentrations from 0.08 to 1.25 mg/L on juvenile giant freshwater prawns (Macrobrachium rosenbergii de Man, 1879) in tanks in the laboratory. Inhibition of ChE in the flesh and in the eyes of the tested shrimps after exposed to diazinon concentrations of 2.7, 27, 67.5 µg/L equivalent to 1%, 10%, 25% LC50-96 h was calculated. The results indicated that diazinon was highly toxic to giant freshwater prawn with a low LC50-96 h of 270 µg/L. The activity of ChE in the flesh was more sensitive to diazinon than that in the eyes. Furthermore, in the future, the activity of ChE in the flesh or in the eyes of shrimps has potential to be used as biomarker for rapid recognition of diazinon contamination in water.
Assuntos
Decápodes , Palaemonidae , Animais , Colinesterases , Diazinon/toxicidade , Água Doce , Humanos , Organofosfatos , Palaemonidae/fisiologiaRESUMO
As global temperatures continue to rise due to global change, marine heatwaves are also becoming more frequent and intense, impacting marine biodiversity patterns worldwide. Organisms inhabiting shallow water environments, such as the commercially relevant ditch shrimp Palaemon varians, are expected to be the most affected by rising temperatures. Thus, addressing species' thermal ecology and climate extinction-risk is crucial to foster climate-smart conservation strategies for shallow water ecosystems. Here, we estimated sex-specific upper thermal tolerance limits for P. varians via the Critical Thermal Maximum method (CTmax), using loss of equilibrium as endpoint. We further calculated thermal safety margins for males and females and tested for correlations between upper thermal limits and shrimps' body size. To determine sex-biased variation in P. varians' traits (CTmax, weight and length), we compared trait variation between females and males through the coefficient of variation ratio (lnCVR). Females displayed an average CTmax value 1.8% lower than males (CTmaxfemales = 37.0 °C vs CTmaxmales = 37.7 °C). This finding may be related to the larger body size exhibited by females (156% heavier and 39% larger than males), as both length and weight had a significant effect on CTmax. The high energetic investment of females in offspring may also contribute to the differences recorded in thermal tolerance. Overall, organisms with a smaller body-size displayed a greater tolerance to elevated temperature, thus suggesting that smaller individuals may be positively selected in warmer environments. This selection may result in a reduction of size-at-maturity and shifts in sex ratio, given the sexual dimorphism in body size of shrimps. The thermal safety margin of P. varians was narrow (â¼2.2 °C for males and â¼1.5 °C for females), revealing the vulnerability of this species to ocean warming and heatwaves.
Assuntos
Biodiversidade , Evolução Biológica , Tamanho Corporal , Palaemonidae/fisiologia , Termotolerância , Aclimatação , Animais , Mudança Climática , Feminino , Masculino , Oceanos e Mares , TemperaturaRESUMO
Contamination is likely to affect the composition of an ecological landscape, leading to the rupture of ecological connectivity among habitats (ecological fragmentation), which may impact on the distribution, persistence and abundance of populations. In the current study, different scenarios within a spatially heterogeneous landscape were simulated in the Heterogeneous Multi-Habitat Assay System (HeMHAS) to evaluate the potential effect that contamination (copper at 0.5 and 25 µg/L) might have on habitat selection by the estuarine shrimp Palaemon varians in combination with two other ecological factors: predator presence and food availability. As a result, P. varians detected and avoided copper; however, in the presence of the predation signal, shrimps shifted their response by moving to previously avoided regions, even if this resulted in a higher exposure to contamination. When encouraged to move towards environments with a high availability of food, a lower connectivity among the shrimp populations isolated by both contamination and predation risk simultaneously was evidenced, when compared to populations isolated only by the risk of predation. These results indicate that contamination might: (i) trigger avoidance in shrimps, (ii) prevent colonization of attractive foraging areas, (iii) enhance populations' isolation and (iv), make populations more susceptible to local extinction.
Assuntos
Palaemonidae , Poluentes Químicos da Água , Animais , Cobre , Ecossistema , Palaemonidae/fisiologia , Dinâmica Populacional , Alimentos Marinhos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
The aims of this research were to perform molecular characterization and biofunctional analyses of giant river prawn Hsp40 and Hsp90 genes (Mr-hsp40 and Mr-hsp90) under various stress conditions. Comparisons of the nucleotide and amino acid sequences of Mr-hsp40 and Mr-hsp90 with those of other species showed the highest similarity scores with crustaceans. Under normal conditions, expression analysis using quantitative real-time RT-PCR (qRT-PCR) indicated that Mr-hsp40 was highly expressed in the gills and testis, and Mr-hsp90 expression was observed in all tissues, with the highest expression in the ovary. The expression patterns of Mr-hsp40 and Mr-hsp90 transcripts under Aeromonas hydrophila challenge and heat-cold shock conditions were examined in gills, the hepatopancreas and hemocytes, at 0, 3, 6, 12, 24, 48 and 96 h by qRT-PCR. Under bacterial challenge, Mr-hsp40 displayed variable expression patterns in all tissues examined during the tested periods. In contrast, upregulated expression of Mr-hsp90 was quickly observed from 3 to 12 h in the gills and hepatopancreas, whereas obviously significant upregulation of Mr-hsp90 was observed in hemocytes at 12-96 h. Under temperature shock conditions, upregulation of Mr-hsp40 expression was detected in all tested tissues, while Mr-hsp90 expression was quickly upregulated at 3-48 h in all tissues in response to 35 °C conditions, and conditions of 35 and 25 °C stimulated its expression in gills and the hepatopancreas at 12 and 48 h, respectively. Silencing analyses of these two genes were successfully conducted under normal, high-temperature (35 °C) and A. hydrophila infection conditions. Overall, knockdown of Mr-hsp40 and Mr-hsp90 effectively induced more rapid and higher mortality than in the PBS control and GFP induction groups in temperature and infectious treatments. Evidence from this study clearly demonstrated the significant functional roles of Mr-hsp40 and Mr-hsp90, which are crucially involved in cellular stress responses to both temperature and pathogenic bacterial stimuli.
Assuntos
Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP90/genética , Palaemonidae/fisiologia , Aeromonas hydrophila/patogenicidade , Animais , Resposta ao Choque Frio/fisiologia , Resistência à Doença/genética , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Resposta ao Choque Térmico/fisiologia , Palaemonidae/microbiologia , Filogenia , TemperaturaRESUMO
In response to the continuous variation of environmental parameters, species must be able to adjust their physiology to overcome stressful conditions, a process known as acclimatization. Numerous laboratory studies have been conducted to understand and describe the mechanisms of acclimation to one environmental stressor (e.g. cyclic hypoxia), but currently our understanding of how acclimation to one stressor can change tolerance to a subsequent stressor is limited. Here, in two different experiments, we used the shrimp Palaemon varians to test how, following 28-days acclimation to cyclic hypoxia (mimicking a cyclic hypoxic regime currently found in its natural habitat), critical thermal maximum (CTmax) and sensitivity to copper (Cu2+) exposure (30 mgL-1) changed in comparison to shrimp acclimated to normoxic conditions and then exposed to thermal stress or Cu2+. Acclimation to cyclic hypoxia improved both CTmax (~1 °C higher than controls) and survival to acute Cu2+ exposure (~30% higher than controls) and induced significant gene expression changes (i.e. up-regulation of heat shock protein 70 - HSP70, hypoxia inducible factor - HIF, phosphoenolpyruvate carboxykinase - PEPCK, glucose 6-P transporter - G6Pt, metallothionein - Mt, and down-regulation of hemocyanin - Hem) in animals acclimated to cyclic hypoxia. Our results demonstrate how acclimation to cyclic hypoxia improved tolerance to subsequent stressors, highlighting the complexity of predicting organismal performance in variable (i.e. where multiple parameters can simultaneously change during the day) environments.
Assuntos
Cobre/metabolismo , Hipóxia , Palaemonidae/fisiologia , Aclimatação , Animais , Cobre/química , Ecossistema , Perfilação da Expressão Gênica , Proteínas de Choque Térmico/metabolismo , Íons , Modelos Biológicos , Temperatura , Regulação para CimaRESUMO
Plastic pollution in the form of nanoplastics poses a global threat to aquatic ecosystems and the organisms inhabiting them. However, few studies have been conducted on the effects of nanoplastic exposure on reproductive development in crustaceans. In order to address this issue, juvenile oriental river prawns (Macrobrachium nipponense) were exposed to different concentrations of 75-nm polystyrene nanoplastics (0, 5, 10, 20, 40 mg/L) for 28 days. In order to study the regulation of reproduction-related genes in the presence of nanoplastics, the Wee1 protein kinase gene (Wee1) and OTU domain ubiquitin aldehyde binding protein gene (OTUB) were selected. In this study, for the first time, the full-length cDNA of Mn-Wee1 and Mn-OTUB were cloned from M. nipponense. Homologous alignments revealed that Mn-Wee1 had a highly conserved function-critical sequence, and that Mn-OTUB was more closely related to OTUB1 than OTUB2. With increasing concentration of nanoplastics, the expression of both genes increased initially, then decreased. The inhibition of expression of Wee1 and OTUB occurred in 40 mg/L group, respectively. Analysis of the data also indicated that nanoplastic exposure might have differing effects on gene expression in M. nipponense male and female reproductive organs.
Assuntos
Palaemonidae , Animais , Proteínas de Artrópodes/genética , DNA Complementar , Ecossistema , Feminino , Expressão Gênica , Masculino , Microplásticos , Palaemonidae/genética , Palaemonidae/fisiologia , ReproduçãoRESUMO
Palaemonid shrimps inhabit osmotic niches from marine to continental waters. They hyper-regulate hemolymph osmolality and ionic concentrations in dilute media, hypo-regulating in concentrated media. Their gill epithelia express ion transporters like the Na+-K+-2Cl- symporter (NKCC) thought to play a role in salt secretion. To examine Cl- hypo-regulatory capability and phylogenetic correlations between gill NKCC mRNA levels and protein expression, we used palaemonids ranging from marine tide pools through estuaries (Palaemon) to coastal and continental fresh waters (Macrobrachium). We established the species' upper critical salinity limits (UL50) and short- (24 h) and long-term (120h) hypo-regulatory abilities at salinities of 80% of their UL50's (80%UL50). The Palaemon species exhibited the highest UL50's and greatest hypo-regulatory capabilities; among the Macrobrachium species, UL50's were higher in the diadromous than in the hololimnetic species. While basal transcript levels of gill NKCC mRNA were highest in P. pandaliformis, levels were unaffected by salinity or exposure time in all species. However, gill NKCC protein abundance increased after 120-h exposure at the 80%UL50 in all Macrobrachium species, except M. potiuna. Unexpectedly, hemolymph hyper-osmoregulatory capability in acclimatization media correlated with gill NKCC protein synthesis, while gill NKCC mRNA expression correlated with hemolymph hyper-Cl- regulation in Macrobrachium. These findings, together with the evolutionary history of osmoregulation in this shrimp clade, suggest a role for the gill NKCC symporter in both salt uptake and secretion. The evolution of NKCC protein expression responsiveness, unlike hemolymph hypo-regulation and NKCC mRNA expression, may have been driven by environmental salinity during niche radiation. SUMMARY STATEMENT: While mRNA expression of the gill Na+-K+-2Cl- symporter is unchanged during acclimation of palaemonid shrimps to saline media, protein expression is up regulated, revealing a role in chloride secretion.
Assuntos
Brânquias/fisiologia , Palaemonidae/genética , Palaemonidae/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Aclimatação , Animais , Evolução Biológica , Ecossistema , Feminino , Água Doce , Hemolinfa/metabolismo , Íons , Cinética , Masculino , Concentração Osmolar , Osmorregulação , Osmose , Filogenia , RNA Mensageiro/metabolismo , Salinidade , Sódio/metabolismo , Especificidade da Espécie , Simportadores/genética , Simportadores/metabolismo , Resultado do Tratamento , Equilíbrio Hidroeletrolítico/fisiologiaRESUMO
Two new species of the palaemonid shrimp genus Typton Costa, 1844 are described based on material from Panama and Mexico. Both species are closely related to T. tortugae McClendon, 1911, a species originally described from the Dry Tortugas, off southern Florida, USA, and later scarcely recorded from other western Atlantic localities, from Bermuda to Mexico and Brazil. Some clarification and additional illustrations are provided for the type material of T. tortugae. Typton jonkayei sp. nov., is described based on material from fouling-encrusting communities dominated by sponges, growing on submerged roots of the red mangrove, Rhizhophora mangle L., in Bocas del Toro, Caribbean coast of Panama. This new species differs from T. tortugae in several morphological details, for instance, on the minor and major chelipeds (second pereiopods), telson, uropod, frontal margin and ambulatory pereiopods. Typton cousteaui sp. nov. is described based on a single ovigerous female dredged in the southern Gulf of California off Baja California Sur, Mexico, previously reported as T. tortugae. This new taxon seems to represent a true cryptic species with no significant morphological divergence from the allopatrically isolated T. tortugae, except for slight morphometric differences. In addition, T. granulosus Ayón-Parente, Hendrickx Galvan-Villa, 2015 is recorded from the Pacific coast of Panama, based on material collected in the Coiba Archipelago. Some taxonomic, distributional and ecological remarks are provided for T. granulosus and the closely related T. serratus Holthuis, 1951.