Ontogeny of decapod crustacean hemocyanin: effects of temperature and nutrition

Vitellogenesis and Embryogenesis in Spiders: A Biochemical Perspective

This review compiles information on the biochemistry of spider reproduction, from vitellogenesis to postembryonic development. Despite the diversity of spiders, biochemical studies on their reproduction remain scarce. The structures, functions, and relationships of vitellogenins and lipovitellins across different groups are compared. Information on two vitellogenin-associated proteins (30 and 47 kDa) is presented and discussed. By analyzing females at different reproductive stages-previtellogenesis, early vitellogenesis, vitellogenesis, and postvitellogenesis-as well as males, we examined lipid and fatty acid synthesis, mobilization, and accumulation in the yolk. Lipid dynamics across vitellogenic organs, such as the intestinal diverticula, hemolymph, and ovaries, were established. Structural lipids, mainly phosphatidylcholine and phosphatidylethanolamine, were the predominant yolk components, followed by triacylglycerols. The gonadosomatic and hepatosomatic indices are described for the first time in spiders, providing a new tool for studying vitellogenesis. Hemocyanin was detected in early spider eggs, suggesting a role in organogenesis, with its concentration increasing in later embryonic stages. In contrast, lipovitellin consumption was observed throughout embryonic development until juvenile emergence. The data compiled in this review provide valuable insights into the molecular interactions underlying a key process for oviparous animals.

Larval feeding activity and use of embryonic resources determine juvenile performance of the common prawn Palaemonserratus

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.

Temperature and hypoxia trigger developmental phenotypic plasticity of cardiorespiratory physiology and growth in the parthenogenetic marbled crayfish, Procambarus virginalis Lyko, 2017

Attempting to differentiate phenotypic variation caused by environmentally-induced alterations in gene expression from that caused by actual allelic differences can be experimentally difficult. Environmental variables must be carefully controlled and then interindividual genetic differences ruled out as sources of phenotypic variation. We investigated phenotypic variability of cardiorespiratory physiology as well as biometric traits in the parthenogenetically-reproducing marbled crayfish Procambarus virginalis Lyko, 2017, all offspring being genetically identical clones. Populations of P. virginalis were reared from eggs tank-bred at four different temperatures (16, 19, 22 and 25 °C) or two different oxygen levels (9.5 and 20 kPa). Then, at Stage 3 and 4 juvenile stages, physiological (heart rate, oxygen consumption) and morphological (carapace length, body mass) variables were measured. Heart rate and oxygen consumption measured at 23 °C showed only small effects of rearing temperature in Stage 3 juveniles, with larger effects evident in older, Stage 4 juveniles. Additionally, coefficients of variation were calculated to compare our data to previously published data on P. virginalis as well as sexually-reproducing crayfish. Comparison revealed that carapace length, body mass and heart rate (but not oxygen consumption) indeed showed lower, yet notable coefficients of variation in clonal crayfish. Yet, despite being genetically identical, significant variation in their morphology and physiology in response to different rearing conditions nonetheless occurred in marbled crayfish. This suggests that epigenetically induced phenotypic variation might play a significant role in asexual but also sexually reproducing species.

Hemocyanin as a biological indicator of artificial light at night stress in sandy beach amphipods

The influence of artificial light at night (ALAN) is becoming evident in marine sandy beaches. These habitats are dominated by species reliant on natural daylight/night regimes, making the identification of biological indicators a priority. We assessed the applicability of hemocyanin, an oxygen-transport protein in the hemolymph of many invertebrates, as an indicator of ALAN-related stress. Unlike total proteins, hemocyanins signal metabolic function and stress, so we expected them to increase in response to ALAN. We adapted spectrophotometry protocols to describe spatial variation in hemocyanins and total proteins in four populations of the talitroid amphipod Americorchestia longicornis. Then, a two-week experiment tested for changes in response to ALAN. Hemocyanin levels increased by 17 % and 40 % with respect to experimental controls after 7 and 14 d, respectively, and were higher than any measurements conducted in the field. These results suggest good prospects for hemocyanin as an indicator of ALAN effects.

Signaling Pathways That Regulate the Crustacean Molting Gland

A pair of Y-organs (YOs) are the molting glands of decapod crustaceans. They synthesize and secrete steroid molting hormones (ecdysteroids) and their activity is controlled by external and internal signals. The YO transitions through four physiological states over the molt cycle, which are mediated by molt-inhibiting hormone (MIH; basal state), mechanistic Target of Rapamycin Complex 1 (mTORC1; activated state), Transforming Growth Factor-β (TGFβ)/Activin (committed state), and ecdysteroid (repressed state) signaling pathways. MIH, produced in the eyestalk X-organ/sinus gland complex, inhibits the synthesis of ecdysteroids. A model for MIH signaling is organized into a cAMP/Ca2+-dependent triggering phase and a nitric oxide/cGMP-dependent summation phase, which maintains the YO in the basal state during intermolt. A reduction in MIH release triggers YO activation, which requires mTORC1-dependent protein synthesis, followed by mTORC1-dependent gene expression. TGFβ/Activin signaling is required for YO commitment in mid-premolt. The YO transcriptome has 878 unique contigs assigned to 23 KEGG signaling pathways, 478 of which are differentially expressed over the molt cycle. Ninety-nine contigs encode G protein-coupled receptors (GPCRs), 65 of which bind a variety of neuropeptides and biogenic amines. Among these are putative receptors for MIH/crustacean hyperglycemic hormone neuropeptides, corazonin, relaxin, serotonin, octopamine, dopamine, allatostatins, Bursicon, ecdysis-triggering hormone (ETH), CCHamide, FMRFamide, and proctolin. Contigs encoding receptor tyrosine kinase insulin-like receptor, epidermal growth factor (EGF) receptor, and fibroblast growth factor (FGF) receptor and ligands EGF and FGF suggest that the YO is positively regulated by insulin-like peptides and growth factors. Future research should focus on the interactions of signaling pathways that integrate physiological status with environmental cues for molt control.

The effects of elevated temperature and PCO2 on the energetics and haemolymph pH homeostasis of juveniles of the European lobster, Homarus gammarus

Regulation of extracellular acid–base balance, while maintaining energy metabolism, is recognised as an important aspect when defining an organism's sensitivity to environmental changes. This study investigated the haemolymph buffering capacity and energy metabolism (oxygen consumption, haemolymph [l-lactate] and [protein]) in early benthic juveniles (carapace length <40 mm) of the European lobster, Homarus gammarus, exposed to elevated temperature and PCO2. At 13°C, H. gammarus juveniles were able to fully compensate for acid–base disturbances caused by the exposure to elevated seawater PCO2 at levels associated with ocean acidification and carbon dioxide capture and storage (CCS) leakage scenarios, via haemolymph [HCO3−] regulation. However, metabolic rate remained constant and food consumption decreased under elevated PCO2, indicating reduced energy availability. Juveniles at 17°C showed no ability to actively compensate haemolymph pH, resulting in decreased haemolymph pH particularly under CCS conditions. Early benthic juvenile lobsters at 17°C were not able to increase energy intake to offset increased energy demand and therefore appear to be unable to respond to acid–base disturbances due to increased PCO2 at elevated temperature. Analysis of haemolymph metabolites suggests that, even under control conditions, juveniles were energetically limited. They exhibited high haemolymph [l-lactate], indicating recourse to anaerobic metabolism. Low haemolymph [protein] was linked to minimal non-bicarbonate buffering and reduced oxygen transport capacity. We discuss these results in the context of potential impacts of ongoing ocean change and CCS leakage scenarios on the development of juvenile H. gammarus and future lobster populations and stocks.

Vitellogenesis in spiders: first analysis of protein changes in different reproductive stages of Polybetes pythagoricus

Vitellogenesis represents one of the most vital processes of oviparous species during which various proteins, carbohydrates, and lipids are synthesized and stored inside the developing oocytes. Through analyzing protein changes in the midgut diverticula, hemolymph, and ovaries of females throughout the different vitellogenic stages of the spider Polybetes pythagoricus, we determined the origin of the different proteins involved in the formation of lipovitellins (LVs) along with the existence of a linkage between the hemocyanin and this vital process. An increase in the total protein content of the midgut diverticula, hemolymph, and ovary occurred throughout vitellogenesis followed by a decrease in those levels after laying. The presence of hemocyanin in egg and in LV2, as well as its accumulation in the ovary throughout the vitellogenesis process, was determined. Considering that all biologic processes depend on the correct structure and function of proteins, this study establishes, for the first time for the Order Araneae, the coexistence of three different origins of vitellogenesis-related proteins: one predominantly ovarian involving peptides of 120, 75, 46, and 30 kDa; another extraovarian one originated from the midgut diverticula and represented by a 170 kDa peptide, and a third hemolymphatic one, represented by the 67 kDa peptide.

Effects of temperature on survival, moulting, and expression of neuropeptide and mTOR signalling genes in juvenile Dungeness crab (Metacarcinus magister)

Mechanistic target of rapamymcin (mTOR) is a highly conserved protein kinase that controls cellular protein synthesis and energy homeostasis. We hypothesize that mTOR integrates intrinsic signals (moulting hormones) and extrinsic signals (thermal stress) to regulate moulting and growth in decapod crustaceans. The effects of temperature on survival, moulting and mRNA levels of mTOR signalling genes (Mm-Rheb, Mm-mTOR, Mm-AMPKα, Mm-S6K and Mm-AKT) and neuropeptides (Mm-CHH and Mm-MIH) were quantified in juvenile Metacarcinus magister Crabs at different moult stages (12, 19 or 26 days postmoult) were transferred from ambient temperature (∼15°C) to temperatures between 5 and 30°C for up to 14 days. Survival was 97-100% from 5 to 20°C, but none survived at 25 or 30°C. Moult stage progression accelerated from 5 to 15°C, but did not accelerate further at 20°C. In eyestalk ganglia, Mm-Rheb, Mm-AMPKα and Mm-AKT mRNA levels decreased with increasing temperatures. Mm-MIH and Mm-CHH mRNA levels were lowest in the eyestalk ganglia of mid-premoult animals at 20°C. In the Y-organ, Mm-Rheb mRNA levels decreased with increasing temperature and increased during premoult, and were positively correlated with haemolymph ecdysteroid titre. In the heart, moult stage had no effect on mTOR signalling gene mRNA levels; only Mm-Rheb, Mm-S6K and Mm-mTOR mRNA levels were higher in intermoult animals at 10°C. These data suggest that temperature compensation of neuropeptide and mTOR signalling gene expression in the eyestalk ganglia and Y-organ contributes to regulate moulting in the 10 to 20°C range. The limited warm compensation in the heart may contribute to mortality at temperatures above 20°C.

Copper homeostasis at the host vibrio interface: lessons from intracellular vibrio transcriptomics

Recent studies revealed that several vibrio species have evolved the capacity to survive inside host cells. However, it is still often ignored if intracellular stages are required for pathogenicity. Virulence of Vibrio tasmaniensis LGP32, a strain pathogenic for Crassostrea gigas oysters, depends on entry into hemocytes, the oyster immune cells. We investigated here the mechanisms of LGP32 intracellular survival and their consequences on the host-pathogen interaction. Entry and survival inside hemocytes were required for LGP32-driven cytolysis of hemocytes, both in vivo and in vitro. LGP32 intracellular stages showed a profound boost in metabolic activity and a major transcription of antioxidant and copper detoxification genes, as revealed by RNA sequencing. LGP32 isogenic mutants showed that resistance to oxidative stress and copper efflux are two main functions required for vibrio intracellular stages and cytotoxicity to hemocytes. Copper efflux was also essential for host colonization and virulence in vivo. Altogether, our results identify copper resistance as a major mechanism to resist killing by phagocytes, induce cytolysis of immune cells and colonize oysters. Selection of such resistance traits could arise from vibrio interactions with copper-rich environmental niches including marine invertebrates, which favour the emergence of pathogenic vibrios resistant to intraphagosomal killing across animal species.

Identification and characterisation of hemocyanin of the fish louse Argulus (Crustacea: Branchiura)

Hemocyanin transports oxygen in the hemolymph of many arthropod species. Within the crustaceans, this copper-containing protein was thought to be restricted to Malacostraca, while other crustacean classes were assumed to employ hemoglobin or lack any respiratory protein. Only recently it has become evident that hemocyanins also occur in Remipedia and Ostracoda. Here we report for the first time the identification and characterisation of hemocyanin in the fish louse Argulus, which belongs to the class of Branchiura. This finding indicates that hemocyanin was the principal oxygen carrier in the stem lineage of the pancrustaceans, but has been lost independently multiple times in crustacean taxa. We obtained the full-length cDNA sequences of two hemocyanin subunits of Argulus foliaceus by a combination of RT-PCR, RACE and Illumina sequencing of the transcriptome. In addition, one full-length and one partial cDNA sequence were derived from the transcriptome data of Argulus siamensis. Western blot analysis confirmed the presence of at least two hemocyanin subunits in A. foliaceus, which are expressed at the mRNA level at a 1:3.5 ratio. The addition to the branchiuran hemocyanin subunits to a multiple sequence alignment of arthropod, hemocyanins improved the phylogenetic resolution within the pancrustacean hemocyanins. Malacostracan, ostracod and branchiuran hemocyanins are distinct from the hexapod and remipede hemocyanins, reinforcing the hypothesis of a close relationship of Remipedia and Hexapoda. Notably, the ostracod hemocyanins are paraphyletic with respect to the branchiuran hemocyanins, indicating ancient divergence and differential loss of distinct subunit types.

Evolution of Respiratory Proteins across the Pancrustacea

Respiratory proteins enhance the capacity of the blood for oxygen transport and support intracellular storage and delivery of oxygen. Hemocyanin and hemoglobin are the respiratory proteins that occur in the Pancrustacea. The copper-containing hemocyanins evolved from phenoloxidases in the stem lineage of arthropods. For a long time, hemocyanins had only been known from the malacostracan crustaceans but recent studies identified hemocyanin also in Remipedia, Ostracoda, and Branchiura. Hemoglobins are common in the Branchiopoda but have also been sporadically found in other crustacean classes (Malacostraca, Copepoda, Thecostraca). Respiratory proteins had long been considered unnecessary in the hexapods because of the tracheal system. Only chironomids, some backswimmers, and the horse botfly, which all live under hypoxic conditions, were known exceptions and possess hemoglobins. However, recent data suggest that hemocyanins occur in most ametabolous and hemimetabolous insects. Phylogenetic analysis showed the hemocyanins of insects and Remipedia to be similar, suggesting a close relationship of these taxa. Hemocyanin has been lost in dragonflies, mayflies, and Eumetabola (Hemiptera + Holometabola). In cockroaches and grasshoppers, hemocyanin expression is restricted to the developing embryo while in adults oxygen is supplied solely by the tracheal system. This pattern suggests that hemocyanin was the oxygen-transport protein in the hemolymph of the last common ancestor of the pancrustaceans. The loss was probably associated with miniaturization, a period of restricted availability of oxygen, a change in life-style, or morphological changes. Once lost, hemocyanin was not regained. Some pancrustaceans also possess cellular globin genes with uncertain functions, which are expressed at low levels. When a respiratory protein was again required, hemoglobins evolved several times independently from cellular globins.

Effect of food availability on the growth and thermal physiology of juvenile Dungeness crabs (Metacarcinus magister)

Juvenile Dungeness crabs spend ~1 year in the San Francisco Estuary, where they undergo considerable growth before returning to the coastal ocean. Previous studies suggest that competition, food scarcity and avoidance of conspecifics may cause some juvenile Dungeness crabs in the San Francisco Estuary to become food limited. Food limitation may force these crabs to forage in higher temperature intertidal environments in the estuary, exposing them to stressful conditions in order to sustain growth and, potentially, necessitating physiological trade-offs in energy allocation between growth and stress tolerance. To investigate the effects of food limitation on aerobic metabolism and physiological performance of crabs, we assessed growth, moulting frequency, metabolic rate, citrate synthase and malate dehydrogenase enzyme activity and cardiac performance, as an index of temperature sensitivity and upper temperature tolerance. Summer- and winter-caught crabs were acclimated to either a high- or a low-food ration for 5 weeks. Overall, our results demonstrated that while food limitation had a negative effect on growth of juvenile Dungeness crabs in both the summer and the winter feeding trials, crabs in the low-food group maintained both metabolic rate at ambient San Francisco Estuary temperatures (15°C; summer trial only) and upper temperature tolerance as determined by failure of cardiac function when compared with crabs in the high-food group (summer and winter trials). Therefore, the ability to maintain stress tolerance when food is limited appears to come as a physiological trade-off to growth. Food-limited crabs were unable to increase their metabolic rate to the same level as that achieved by well-fed crabs; therefore, if exposure to elevated temperatures persists and requires more energy than can be met by crabs in their food-limited state, physiological performance may be compromised.

A new haemocyanin in cuttlefish (Sepia officinalis) eggs: sequence analysis and relevance during ontogeny

Background

Haemocyanin is the respiratory protein of most of the Mollusca. In cephalopods and gastropods at least two distinct isoforms are differentially expressed. However, their physiological purpose is unknown. For the common cuttlefish Sepia officinalis, three isoforms are known so far, whereas for only two of them the complete mRNA sequences are available. In this study, we sequenced the complete mRNA of the third haemocyanin isoform and measured the relative expression of all three isoforms during embryogenesis to reveal a potential ontogenetic relevance.

Results

The cDNA of isoform 3 clearly correlates to the known Sepia officinalis haemocyanin subunits consisting of eight functional units and an internal duplicated functional unit d. Our molecular phylogenetic analyses reveal the third isoform representing a potentially ancestral haemocyanin isoform, and the analyses of the expression of haemocyanin type 3 reveal that haemocyanin type 3 only can be observed within eggs and during early development. Isoforms 1 and 2 are absent at these stages. After hatching, isoform 3 is downregulated, and isoform 1 and 2 are upregulated.

Conclusions

Our study clearly shows an embryonic relevance of the third isoform, which will be further discussed in the light of the changes in the physiological function of haemocyanin during ontogeny. Taken together with the fact that it could also be the isoform closest related to the common ancestor of cuttlefish haemocyanin, the phylogeny of cuttlefish haemocyanin may be recapitulated during its ontogeny.

Dodecamer is required for agglutination of Litopenaeus vannamei hemocyanin with bacterial cells and red blood cells

Hemocyanins are multi-functional proteins, although they are well known to be respiratory proteins of invertebrate to date. In the present study, the agglutination ability of two oligomers of hemocyanin, hexamer and dodecamer, with pathogenic bacteria and red blood cells (RBCs) is investigated in pacific white shrimp, Litopenaeus vannamei. Hexameric hemocyanin exhibits an extremely high stability even in the absence of Ca(2+) and in alkaline pH. Dodecamer (di-hexamer) is easily dissociated into hexamers in unphysiological conditions. Hexamer and dodecamer are interchanged reciprocally with environmental conditions. Both oligomers can bind to bacteria and RBCs, but agglutination is observed only using dodecamer but not using hexamer in agglutination assay. However, the agglutination is detected when hexamer is utilized in the presence of antiserum against hemocyanin. These results indicate that dodecamer of hemocyanin is required for agglutination with bacteria and RBCs. It can be logically inferred that there is only one carbohydrate-binding site to bacterial cells and RBCs in the hexamer, while at least two sites in the dodecamer. Our finding has provided new insights into structural-functional relationship of hemocyanin.

Plasticity in the timing of physiological development: Physiological heterokairy — What is it, how frequent is it, and does it matter?

The study of developmental sequences of physiological traits could be an important way of placing comparative developmental physiology (CDP) within the research agenda being forged by work on developmental plasticity. Here we focus on the concept of heterokairy defined by Spicer & Burggren in 2003 as changes in the timing of physiological development in an individual. The role of this concept in the future of the CDP is discussed. First we provide an historical perspective of the ideas that have led to the investigation of sequences in CDP. This is followed by a re-examination and clarification of the definition of physiological heterokairy before empirical case studies that (explicitly or implicitly) demonstrate physiological heterokairy are reviewed. We suggest that physiological heterokairy can be demonstrated through a wide range of invertebrate and vertebrate examples. However, care must be taken when inferring that heterokairy as a pattern is always the result of heterokairic processes as there is evidence that physiological heterokairy could result from the altered timing of both homologous or analogous physiological mechanisms. We conclude by discussing the potential link between heterokairy and heterochrony and suggest that the investigation of this link should be a major goal for workers in both CDP and developmental plasticity.

The molecular heterogeneity of hemocyanin: Its role in the adaptive plasticity of Crustacea

Crustacean hemocyanin (Hc) represents a unique case of molecular heterogeneity among oxygen-carrying proteins. The existence of different genes, encoding single polypeptide chains, constitutes the genetic basis for the inter- and intra-specific polymorphism. In addition, the large number of Hc subunits within crustacean species, together with their flexible expression, provides an efficient intrinsic mechanism of modulation of oxygen transport. This review presents a description and classification of the various aspects of crustacean Hc heterogeneity and defines its role in a perspective of crustacean adaptive physiology.