Seasonal variations in the intermediate metabolism of Parastacus varicosus (Crustacea, Decapoda, Parastacidae)

Identifying the genes involved in the egg-carrying ovigerous hair development of the female blue crab Callinectes sapidus: transcriptomic and genomic expression analyses

BACKGROUND

Crustacean female sex hormone (CFSH) controls gradually developing adult female-specific morphological features essential for mating and brood care. Specifically, ovigerous hairs are developed during the prepuberty molt cycle of the blue crab Callinectes sapidus that are essential for carrying the eggs until they finish development. Reduced CFSH transcripts by CFSH-dsRNA injections result in fewer and shorter ovigerous hairs than the control. This study aimed to identify the specific genes responsible for ovigerous hair formation using transcriptomic, genomic and expression analyses of the ovigerous setae at three stages: prepuberty at early (OE) and late premolt (OL), and adult (AO) stages.

RESULTS

The de novo Trinity assembly on filtered sequence reads produced 96,684 Trinity genes and 124,128 transcripts with an N50 of 1,615 bp. About 27.3% of the assembled Trinity genes are annotated to the public protein sequence databases (i.e., NR, Swiss-Prot, COG, KEGG, and GO databases). The OE vs. OL, OL vs. AO, and OE vs. AO comparisons resulted in 6,547, 7,793, and 7,481 differentially expressed genes, respectively, at a log2-fold difference. Specifically, the genes involved in the Wnt signaling and cell cycle pathways are positively associated with ovigerous hair development. Moreover, the transcripts of ten cuticle protein genes containing chitin-binding domains are most significantly changed by transcriptomic analysis and RT-qPCR assays, which shows a molt-stage specific, down-up-down mode across the OE-OL-AO stages. Furthermore, the expression of the cuticle genes with the chitin-binding domain, Rebers and Riddiford domain (RR)-1 appears at early premolt, followed by RR-2 at late premolt stage. Mapping these 10 cuticle protein sequences to the C. sapidus genome reveals that two scaffolds with a 549.5Kb region and 35 with a 1.19 Mb region harbor 21 RR1 and 20 RR2 cuticle protein genes, respectively. With these findings, a putative mode of CFSH action in decapod crustaceans is proposed.

CONCLUSIONS

The present study describes a first step in understanding the mechanism underlying ovigerous hair formation in C. sapidus at the molecular level. Overall, demonstrating the first transcriptome analysis of crustacean ovigerous setae, our results may facilitate future studies into the decapod female reproduction belonging to the suborder Pleocyemata.

Seasonal variability of metabolic markers and oxidative balance in freshwater amphipod Hyalella kaingang (Crustacea, Amphipoda)

Amphipods are widely used as bioindicator organisms, in view of their ease of collection and cultivation, sexual dimorphism and abundance, in aquatic environments. In the present study male (n=30) and female (n=30) amphipod Hyalella kaingang were collected during the middle of each season from a nature preserve (Research Center PRÓ-MATA) in São Francisco de Paula, Southern Brazil. Proteins, glycogen, lipids, triglycerides, glycerol, and lipid peroxidation (superoxide dismutase, catalase, and glutathione S-transferase activity) were measured. The results obtained for the markers of energy metabolism, antioxidant enzymes, and lipid peroxidation revealed a clear seasonal variation. The patterns of proteins, glycerol, and glutathione S-transferase activity did not differ between sexes; conversely, differential responses in males and females over the year were observed for all other parameters (glycogen, lipids, triglycerides, lipid peroxidation, and superoxide dismutase and catalase activity). These responses appear to be strongly influenced by a prolonged reproductive period (autumn through spring, peaking in autumn); by the degree of exploratory activity, particularly in the summer and autumn; and by abiotic factors, such as temperature and photoperiod. The responses observed in the summer and autumn (decrease in levels of proteins, glycogen and fats, and increase in lipid peroxidation levels and glutathione S-transferase activity), suggest that this season represents a critical time point for these animals. The parameters studied herein may be used as biomarkers to assess the environmental conditions in the aquatic habitat.

Biomonitoring of environmental stress in Pollicipes pollicipes from the northern coast of Portugal: a non-destructive approach using haemolymph

In the intertidal area, the interactions between anthropogenic contaminants and natural variations (biotic and abiotic factors) are poorly understood. Consequently, there is a great need for new assessment procedures to characterize the biological responses occurring in organisms from this extreme environment. Considering the intrinsic inter-individual variations among organisms from a single population, it is important to propose new methods that address this variability, by validating a sampling strategy in target groups of organisms, encompassing seasonal fluctuations. This strategy must however be less invasive than traditional methods, avoiding the mandatory sacrifice of the sampled organisms. By doing so, it is also possible to increase the ecological relevance of obtainable data, and contribute to minimize damage to endangered species. The main purpose of the present study was to assess the influence of seasonal variations in the responses elicited by anthropogenic compounds on a marine crustacean species, by using a biomarker-based approach. According to this purpose, the seasonal variations in key physiological responses (biomarkers) were investigated in the crustacean Pollicipes pollicipes from the Northern coast of Portugal. Biomarkers used for this purpose were the activity of the phase II biotransformation isoenzymes glutathione-S-transferases (GSTs), the activity of cholinesterases (ChEs), and the levels of lipid peroxidation (TBARS). All biomarkers were quantified in distinct tissues (such as cirri, and peduncle) and haemolymph (a non-destructive source of biological samples). The glycogen content in peduncle tissue, and the variation in haemocyte number in haemolymph were also analyzed. Samples were collected monthly, during a year, in Lavadores, located in the proximity of an estuarine area (Douro River). The results showed a seasonal pattern in all tested biomarkers. The results also showed a significant increase in GSTs activities, and in peroxidative damage, especially during warmer months. The lowest ChEs values were recorded during the rainy season. The results also showed a similar pattern among all tested tissues, validating the proposed use of the haemolymph as a source tissue for non-lethal sampling strategy for biomarker determinations. Glycogen content was apparently related to the reproductive cycle, with lower values being observed in spring and summer. Total haemocyte count (THC) increased during summer months. The results pointed to an influence of natural variations in the levels of biomarkers in P. pollicipes, highly dependent upon abiotic factors, a factor that must be considered when interpreting biological responses elicited by anthropogenic contaminants from the marine coastal environment. The validation of haemolymph as a non-lethal source tissue for the quantification of biomarkers was successfully attained, opening the possibility of less invasive and almost unlimited sampling in a small number of organisms.

Effect of temperature on biochemical composition, growth and reproduction of the ornamental red cherry shrimp Neocaridina heteropoda heteropoda (Decapoda, Caridea)

The effect of water temperature on biochemical composition, growth and reproduction of the ornamental shrimp, Neocaridina heteropoda heteropoda, was investigated to determine the optimum temperature for its culture. The effect of embryo incubation temperature on the subsequent performance of juveniles was also evaluated. Ovigerous females and recently hatched juveniles (JI) were maintained during egg incubation and for a 90-day period, respectively, at three temperatures (24, 28 and 32°C). Incubation period increased with decreasing water temperature, but the number and size of JI were similar among treatments. At day 30 of the 90-day period, body weight and growth increment (GI) at 24°C were lower than those at 28 and 32°C. On subsequent days, GI at 24°C exceeded that at 28 and 32°C, leading to a similar body weight among treatments. These results suggest growth was delayed at 24°C, but only for 30 days after hatching. The lipid concentration tended to be lowest, intermediate and highest at 28, 32 and 24°C, respectively, possibly as a consequence of the metabolic processes involved in growth and ovarian maturation. Protein and glycogen concentrations were similar among treatments. Both the growth trajectory and biochemical composition of shrimps were affected by the temperature experienced during the 90-day growth period independently of the embryo incubation temperature. During the growth period, shrimps reached sexual maturity and mated, with the highest proportion of ovigerous females occurring at 28°C. All the females that matured and mated at 32°C lost their eggs, indicating a potentially stressful effect of high temperature on ovarian maturation. Based on high survival and good growth performance of shrimps at the three temperatures tested over the 90-day period it is concluded that N. heteropoda heteropoda is tolerant to a wide range of water temperatures, with 28°C being the optimum temperature for its culture.

Baseline defense system of commercial male king crab Lithodes santolla from the Beagle Channel

Environmental and physiological variations influence the steady-state concentration of free oxygen radicals in cells. Because of the seasonal life cycle of Lithodes santolla in the Beagle Channel, a baseline study of the antioxidant physiological variations along the seasons is necessary for a better understanding of its ecophysiology. The aim of this study was to evaluate the seasonal variations in gills, hemolymph, muscle and hepatopancreas of the: i) enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione transferase; ii) ascorbic acid and total glutathione; iii) lipid peroxidation and protein oxidation; iv) glucose, proteins and pH. Seasonality found in the antioxidant defense system of L. santolla from the Beagle Channel acts in a collaborative way during the most relevant life cycle phases (reproduction and molting), avoiding a long term oxidative stress. The antioxidant system also shows changes in the enzymatic activities likely caused by the environmental factors, such as low temperatures during winter and spring seasons.

Transcriptome survey of the lipid metabolic pathways involved in energy production and ecdysteroid synthesis in the salmon louse Caligus rogercresseyi (Crustacea: Copepoda)

The goal of this study was to identify and analyze the lipid metabolic pathways involved in energy production and ecdysteroid synthesis in the ectoparasite copepod Caligus rogercresseyi. Massive transcriptome sequencing analysis was performed during the infectious copepodid larval stage, during the attached chalimus larval stage, and also in female and male adults. Thirty genes were selected for describing the pathways, and these were annotated for proteins or enzymes involved in lipid digestion, absorption, and transport; fatty acid degradation; the synthesis and degradation of ketone bodies; and steroid and ecdysteroid syntheses. Differential expression of these genes was analyzed by ontogenic stage and discussed considering each stage's feeding habits and energetic needs. Copepodids showed a low expression of fatty acid digestion genes, reflected by a non-feeding behavior, and the upregulation of genes involved in steroid biosynthesis, which was consistent with a pathway for cholesterol synthesis during ecdysis. The chalimus stage showed an upregulation of genes related to fatty acid digestion, absorption, and transport, as well as to fatty acid degradation and the synthesis of ketone bodies, therefore suggesting that lipids ingested from the mucus and skin of the host fish are metabolized as important sources of energy. Adult females also showed a pattern of high lipid metabolism for energy supply and mobilization in relation to reproduction and vitellogenesis. Adult females and males revealed different lipid metabolism patterns that reflected different energetic needs. This study reports for the first time the probable lipid metabolic pathways involved in the energy production and ecdysteroid synthesis of C. rogercresseyi.

Behavioural and biochemical stress responses of Palinurus elephas after exposure to boat noise pollution in tank

This study examined the effects of boat noise on the behavioural and biochemical parameters of the Mediterranean spiny lobster (Palinurus elephas). The experiment was conducted in a tank equipped with a video and audio recording system. 18 experimental trials, assigned to boat noise and control conditions, were performed using lobsters in single and group of 4 specimens. After a 1h habituation period, we audio- and video-recorded the lobsters for 1h. During the experimental phase, the animals assigned to the boat groups were exposed to boat noise pollution (a random sequence of boat noises). Exposure to the noise produced significant variations in locomotor behaviours and haemolymphatic parameters. Our results indicate that the lobsters exposed to boat noises increased significantly their locomotor activities and haemolymphatic bioindicator of stressful conditions such as glucose, total proteins, Hsp70 expression and THC when tested both singly and in groups.

Seasonal and gender-related differences in morphometric features and cellular and biochemical parameters of Carcinus aestuarii from the Lagoon of Venice

In this study, the seasonal variations in the morphometric features and in the cellular and biochemical parameters of the haemolymph were investigated in both male and female crabs (Carcinus aestuarii). Crabs were seasonally (November 2010-August 2011) collected from the Lagoon of Venice, and the moult stage, weight, width and length of the carapace, and width and length of the bigger chela were evaluated. In addition, the total haemocyte count (THC), haemocyte diameter and volume, haemolymph glucose and total protein levels, and haemolymph phenoloxidase (PO) and N-acetyl-β-glucosaminidase (NAG) activities were measured. The results demonstrated that the collected crabs were all in the intermoult stage and that the males were bigger than the females. A two-way ANOVA revealed a significant effect of season on the THC and the haemocyte volume and a significant influence of gender on the haemocyte diameter. Season and gender significantly affected the haemolymph glucose concentration, whereas haemolymph protein levels were dependent only on the season. In addition, both season and gender significantly influenced the PO and NAG activities in the haemolymph. Overall, the results demonstrated that crab morphometric features as well as haemolymph cellular and biochemical parameters varied markedly as a function of both season and gender.

Seasonal variations in the biochemical composition and reproductive cycle of the ghost crab Ocypode quadrata (Fabricius, 1787) in Southern Brazil

The ghost crab, Ocypode quadrata, is found on sandy beaches from the United States to Southern Brazil. Because there is still little information about the metabolism and reproduction of O. quadrata on the southern coast of Brazil, the objectives of this study were to (i) evaluate the effect of seasonal variations on the carbohydrate, lipid, and protein metabolism of O. quadrata at Rondinha Beach, a beach with high anthropogenic activity, and to compare it with data from Siriú Beach, which has less human activity; and (ii) describe the effect of seasonal variations on the histological characteristics of male and female gonads, in order to assess the reproductive capacity of the crabs. The gonads of male crabs showed no significant variations in the gonadosomatic index (GSI) and glycogen levels; however, histological analysis of the testes revealed that they are mature in the summer. In females, the GSI and glycogen values are higher in summer, concomitantly with the presence of mature oocytes. These results suggest that the reproductive peak of O. quadrata occurs in summer. The seasonal analysis of the biochemical parameters, as well as comparison with Siriú Beach, demonstrated that the ghost crabs of Rondinha Beach have a different pattern of metabolism than those of Siriú. This difference may be a consequence of differences in the environmental conditions as well as in the anthropogenic pressures, such as vehicle traffic and the increase in human population at the beach in summer.

Influence of season and sex on the contents of minerals and trace elements in brown crab (Cancer pagurus, Linnaeus, 1758)

Cancer pagurus is much appreciated in Southern Europe, where the muscle, hepatopancreas, and gonads are consumed regularly with peaks in summer and December. The elemental contents of C. pagurus edible tissues were analyzed in this study during the four seasons. Results indicate that the content varied with tissue, season, and sex. The hepatopancreas had more S, Cl, Ca, Br, Sr, Fe, Cu, Cd, and Pb, the gonads had a higher concentration of Na, and the muscle was richer in Zn. Autumn and winter corresponded to a high Mg, S, Cl, K, Ca, Fe, and Zn content in both the muscle and hepatopancreas. Female gonads had more Fe, Zn, As, and Se than males but less Ca, Cl, Br, and Sr. Regarding toxic elements for human consumption, the levels of As, Hg, and Pb found in all edible tissues pose minimal risks to consumers. However, Cd concentration in the hepatopancreas was always above the action limit. Therefore, we recommend moderate hepatopancreas consumption.

Seasonal variation of the effect of high-carbohydrate and high-protein diets on the intermediate metabolism of Parastacus brasiliensis (Crustacea, Decapoda, Parastacidae) maintained in the laboratory

The goal of this study was to evaluate the effect of a high-carbohydrate diet (HC) and a high-protein diet (HP) on the metabolism of the crayfish Parastacus brasiliensis (Von Martens, 1869), collected in different seasons and maintained in the laboratory for 15 days. Crayfish were collected monthly from January 2002 to January 2004 at São Francisco de Paula, Southern Brazil, in Guarapirá stream. In the laboratory, the animals were kept submerged in aquariums under controlled conditions. They were fed ad libitum, for 15 days with either a HC or HP diet. At the end of this period, haemolymph samples were collected, as were hepatopancreas, gills, and abdominal muscle that were removed for determination of glycogen, free glucose, lipids, and triglycerides. The haemolymph samples were used for determination of glucose, proteins, lipids, and triglycerides. Statistical analysis (ANOVA) revealed significant seasonal differences in biochemical composition in crayfish maintained on HC or HP diets. Independent of the diets offered to the animals and the controlled conditions for 15 days, the indications of seasonality were unchanged. The observed changes seemed to be related to the reproductive period. Moreover, the HC diet increased all energy reserves in adult parastacids, which may aid in reproduction.

Seasonal variations in the intermediate metabolism of the crayfish Parastacus brasiliensis (Crustacea, Decapoda, Parastacidae) in the natural environment and experimental culture

The goal of this study was to evaluate the effects of seasonal variations on energy metabolism in different tissues of the freshwater crayfish Parastacus brasiliensis (von Martens, 1869). Crayfish were collected monthly from January 2001 to January 2003 in São Francisco de Paula, Rio Grande do Sul, Brazil, in a stream and in a culture tank. Haemolymph samples were collected from each crayfish in the field with a syringe, by puncturing the membrane at the base of the chelipeds. Hepatopancreas, gills, and abdominal muscle were removed for determination of free glucose, glycogen, total lipids, and triglycerides. The haemolymph samples were used for determination of glucose, total proteins, total lipids, and triglycerides. Statistical analysis revealed significant differences in biochemical composition in crayfish collected in the stream compared to the experimental tank during the year, principally in glucose and triglycerides in haemolymph, glycogen and total lipids in all tissues study, and triglycerides only in abdominal muscle. The regular food intake partially modified these seasonal variations of the metabolic pattern. Environmental conditions (e.g., food availability and water temperature) and reproductive period appeared to be the main factors influencing the seasonal patterns of variation in energy metabolism.

Seasonal variations in the biochemical composition of the crayfish Parastacus defossus (Crustacea, Decapoda) in its natural environment

The crayfish Parastacus defossus occurs in Uruguay and the state of Rio Grande do Sul in Brazil. It lives in swamps and lakes, where it digs sloped subterranean tunnels that are used as burrows. Because there is little information about the biology, physiology and ecology of this species, the aim of this study was to identify the seasonal variations of its carbohydrate and lipid metabolism. Crayfish were collected monthly (from November 2002 to February 2004) in the Lami region, Porto Alegre municipality (30 degrees 11'41''S-51 degrees 06'00''W). Haemolymph samples, used for determination of glucose, total proteins, triglycerides, total cholesterol and total lipids, were collected in the field using potassium oxalate as an anti-clotting agent. The animals and haemolymph samples were immediately frozen in the field. In the laboratory, the hepatopancreas, gills and abdominal muscles were removed for determination of glycogen, triglycerides, total cholesterol and total lipids. The findings suggest that in P. defossus, lipids are an important reserve of energy used during reproduction in both males and females; whereas glycogen may be used during periods of intense activity or environmental stress.