Intermoult Cycle Research Articles

Reproductive status of the blood-spotted swimming crab, Portunus sanguinolentus (Herbst, 1783) (Brachyura, Portunidae) landed off Cochin, India

Abstract Portunus sanguinolentus (Herbst, 1783) is an important commercial crab with a wide distribution along the Indian coast. In Kerala it is landed mainly in trawls, and ranks first in the landings in most years, recording about 50% of the crab landings of the state during 2012-2019, with the exception of 2014. Females dominate the fishery and their sizes range between 55 and 170 mm carapace width (CW), with 90-110 mm being dominant in the landings. Berried females are recorded throughout the year, without any regular dominance in a particular month, although during March-May good percentages of these are observed in overall landings. Newly spawned eggs are bright yellow/orange in colour, with an average size of 270 μm, and by the time of hatching the colour changes to dark grey, and it takes 8-10 days to hatch to the first zoea stage. Fecundity in numbers of eggs varied between 80 960 and 2 357 004 with an average of 512 914 for females of different size groups from 81 to 170 mm CW. Captive studies showed that the species is capable of multiple spawnings, with a maximum of three in an intermoult cycle. Size at maturity (LM50) in females was estimated at 86.5 mm CW and in males at 80.1 mm CW. All the females were mature above 120 mm CW and mature females below 70 mm CW were not recorded in the landed crabs. The smallest size of the mature and berried females recorded in the landings was 71 mm CW/22 g and 80 mm CW/32 g, respectively. In the landings, males comprised sizes between 51-170 mm carapace width (CW) with 91-105 mm forming the major size group contributing to the fishery. In males, 100% maturity was observed in crabs above the size of 95 mm CW, whereas sizes below 60 mm CW were immature. The smallest size of the mature male crab recorded in the landings was 60 mm CW/16 g. Minimum Legal Size (MLS) was implemented in the state in 2016 and for P. sanguinolentus. MLS is fixed at 70 mm CW and it has been proven that this helps in the sustainable utilization of the resource.

THE SHAPE OF CALCIUM CARBONATE DEPOSITS AS AN EXTERNAL MARKER FOR FEMALE REPRODUCTIVE STATUS IN TERRESTRIAL ISOPODS

Abstract The shape of sternal calcium carbonate deposits (CCD) preceding moult was used as a diagnostic character to distinguish between reproductive and non-reproductive females in six species of terrestrial isopods belonging to different families. Samples in the wild at the beginning of the reproductive season revealed females with CCD of incomplete shape, with a diamond-shaped opening at the level of central furrow. All the females showing this pattern made a parturial moult a few days later, while all females showing complete CCD made a normal moult. A laboratory experiment confirmed that these characteristics were diagnostic for females performing a secondary vitellogenesis. These females were receptive to mating at that time, provided the stage of the intermoult cycle was not too early. Screening the CCD shape is therefore a non-destructive method that can be used for routine diagnosis of females' reproductive status in terrestrial isopods.

The Shape of Calcium Carbonate Deposits as an External Marker for Female Reproductive Status in Terrestrial Isopods

The shape of sternal calcium carbonate deposits (CCD) preceding moult was used as a diagnostic character to distinguish between reproductive and non-reproductive females in six species of terrestrial isopods belonging to different families. Samples in the wild at the beginning of the reproductive season revealed females with CCD of incomplete shape, with a diamond-shaped opening at the level of central furrow. All the females showing this pattern made a parturial moult a few days later, while all females showing complete CCD made a normal moult. A laboratory experiment confirmed that these characteristics were diagnostic for females performing a secondary vitellogenesis. These females were receptive to mating at that time, provided the stage of the intermoult cycle was not too early. Screening the CCD shape is therefore a non-destructive method that can be used for routine diagnosis of females’ reproductive status in terrestrial isopods.

Ecdysteroid titres in haemolymph and other tissues during moulting and reproduction in the terrestrial isopod, Oniscus asellus (L.)

Summary Haemolymph ecdysteroid titres were determined throughout the intermoult cycle of Oniscus asellus and related to ecdysteroid-related physiological events. In non-breeding females, ecdysteroid titres rise during premoult to a peak two days prior to ecdysis in synchrony with formation of a new cuticle in the posterior half of the animal. However, the anterior half does not form cuticle during this time, but instead accumulates calcium. Thus, anterior and posterior halves of the epidermis respond differently to the same levels of ecdysteroids. The anterior half secretes a new cuticle at a later time and at a very low ecdysteroid titre. During the first breeding moult of a season, differentiation of a brood pouch commences in early premoult and the rise in ecdysteroid titre is delayed by two weeks. Both vitellogenin synthesis by the fat body and oocyte growth closely parallel the ecdysteroid titre. Although both of these processes are thought to be influenced by ecdysteroids, the titres of breeding and non-breeding females did not differ, indicating that other factors determine whether or not vitellogenesis will occur in the presence of ecdysteroids. Together, these findings show that Oniscus displays ecdysteroid-related events in strikingly unusual ways which raise questions concerning the regulation of cellular responses to ecdysteroids. The hepatopancreas accumulates ecdysteroids to levels well above those in the haemolymph during late premoult and appears to be the main route for their elimination from the haemolymph. Ecdysteroids in the hepatopancreas are translocated rapidly into the hindgut and discarded with the hindgut cuticle at the posterior ecdysis.

Vitellogenesis in the terrestrial isopod,Oniscus asellus(L.): Characterization of vitellins and vitellogenins and changes in their synthesis throughout the intermoult cycle

Summary Egg vitellin of the terrestrial isopod Oniscus asselus is a 290 kD, female-specific lipoglyco-protein (V1) comprising two subunits, A (98 kD) and B (82 kD). An additional related protein (V2, 180 kD) was found in developing oocytes but not in mature eggs. Vitellogenin (VG) is electrophoretically and immunologically indistinguishable to V1 and was detected in oocytes, fat body and haemolymph of vitellogenic females. In vitro incorporation studies revealed that VG is synthesized by both fat body and ovaries, but by no other tissues of either females or males. Oniscus VG, therefore, has both intra- and extra-ovarian origins. Following long-term incorporation, the VG synthesized by either fat body or ovaries comprises only subunits A and B of V1. However, following short-term incorporation, larger polypeptides are present in these tissues, which are also recognized by an antiserum raised against V1. It is speculated that VG in Oniscus is synthesized as a large polypeptide which is subsequently processed to smaller fragments. Synthesis of VG by explants of fat body was studied throughout the intermoult cycle. A single large peak of VG synthesis was seen in the second half of premoult; during this time, VG comprises 40% of the total protein synthesized by fat body and oocytes increase in volume 100-fold. The chronology of VG synthesis and oocyte growth are related to known times of release of hormones in Oniscus. It is suggested that vitellogenesis is regulated by both ecdysteroids and neuropeptide(s) from the sinus gland.

Spermatophore formation in the white shrimp, Penaeus vannamei Boone 1931: dependence on the intermoult cycle

Spermatophore regeneration was studied in Penaeus vannamei to determine its relationship to the intermoult cycle. The spermatophore and sperm mass arrive in the terminal ampulla during the night of moulting. Ecdysis does not induce the release of melanized spermatophores. Sperm quality assessed by the percentage of abnormal sperm was found to be constant during the intermoult cycle. However, spermatophore colour evolves from a translucent state (day 1 to day 6) to a pearly colour (day 6 to day 12) then a white colour (day 10 to day 14). Spermatogenesis is not related to the intermoult cycle and seems to be continuous in captive males.

Storage and translocation of integumentary calcium during the moult cycle of the terrestrial isopod Oniscus asellus (L.)

The calcium content of pieces of integument of standardized size from various regions of the body was measured at all 15 stages of the intermoult cycle. Calcium resorbed from the posterior integument during premoult is stored mainly in the sternal calcium deposits of the anterior region, which contain 20% of total body calcium in late premoult. Earlier arguments that the deposits are not a store of calcium are refuted. These deposits are similar to gastroliths in both structure and function. After posterior ecdysis, calcium in the deposits is resorbed rapidly and employed in calcification of the new posterior exocuticle. Calcium is then resorbed from the general anterior integument within 24 h and may accumulate transiently in the haemolymph. During this period resorption of integumentary calcium and calcification proceed simultaneously in the anterior and posterior regions of the animal. Ecdysis of the anterior region then occurs, and calcium from the haemolymph is employed in calcification of the new anterior exocuticle. Forty-eight percent of intermoult calcium content is conserved. However, both exuviae are eaten and it is argued that further calcium is conserved by resorption from the exuviae within the gut. It is suggested that this calcium, together with dietary calcium, is employed in calcification of the endocuticle after ecdysis. It is proposed that comparable events occur in all crustaceans that conserve calcium, but are rendered especially dramatic in isopods, owing to the unusual biphasic pattern of cuticle secretion.

Protein phosphorylation in the larval epidermis of Locusta migratoria: Role of cyclic AMP and 20-hydroxyecdysone

Cyclic nucleotide-dependent and cyclic nucleotide-independent protein kinase (PK) activities were quantified in the wing-pad epidermis of Locusta migratoria during the fifth larval instar. A low level of cyclic nucleotide-independent PK activity was detected in this tissue, whereas no PK-C (Ca 2+- and phospholipid-dependent enzyme) activity was found. The main cyclic nucleotide-PK activity was cAMP-PK and large changes were observed during the intermoult. Concomitant increases in cAMP-PK activity and cAMP-dependent phosphorylation of several endogenous polypeptide substrates occurred during the last part of the intermoult cycle. The most marked 32P-incorporation was observed in a 43 kDa polypeptide. These changes could be correlated with the peak of 20-OH-ecdysone in both hemolymph and integument. In vitro incubation of wing-pads with 20-OH-ecdysone (48 h) did not change cAMP-PK activity, but there were major changes in the pattern of endogenous phosphoproteins in particular the appearance of 43 and 45 kDa phosphoproteins. Two-dimensional analysis revealed several groups of phosphorylated spots. The results indicate a close relationship between certain cAMP-dependent phosphorylated polypeptides and the action of 20-OH-ecdysone.

O ciclo da intermuda em Macrobrachium borellii (Nobili, 1896) (Crustacea, Decapoda, Palaemonidae): a influência da temperatura e do comprimento do animal

Foram realizados estudos de laboratório sobre o camarão de água doce do sul do Brasil Macrobrachium borellii (Nobili, 1896). Foram analisadas as relações entre as médias das temperaturas e a duração do ciclo de intermuda e entre o tamanho do corpo do animal e a duração do ciclo.

Sensitivity of juvenile lobsters, Homarus americanus L., to different concentrations of malachite green during various states of the intermoult cycle

Abstract. Survival of the early stages (egg, larva and juvenile) of the American lobster, Homarus americanus L., reared under controlled conditions has often been threatened by a variety of fungi and microbial epibionts. A preliminary study was conducted for the purpose of defining toxicity levels of malachite green for 5th stage juveniles during each of the following intermoult (or fused intermoult) states: A‐B, C4, D0 and D2‐D3 Irrespective of exposure time or concentration, all the lobsters treated during intermoult state A‐B died. This contrasts with seemingly good survival of lobsters in intermoult states C4, D0 and D2‐ D3 treated at concentrations of 900 mg/1 malachite green for exposure periods of 10 min. The findings suggest that an effective treatment combination for lobsters immersed in malachite green may be one which is employed during intermoult state C4, for about 6min and at concentrations of about 700–800 mg/l.

CALCIUM BALANCE AND MOULTING IN THE CRUSTACEA

Summary1. Crustaceans have a high content of calcium, which is chiefly located in the skeleton as calcium carbonate. Calcium is generally the most abundant cation in the body.2. During intermoult, the exoskeleton is usually fully calcified and the animal is in calcium equilibrium with its environment.3. In the premoult stages calcium is resorbed from the skeleton and may be lost to the environment or stored within the body. Typically, losses are high and storage is small in aquatic species, whilst most terrestrial forms store much larger amounts of calcium and losses are reduced. Loss of calcium in soluble form by aquatic species must be by outward transport across the gills.4. Calcium is stored in a variety of different ways, usually with a common taxonomic theme. The main forms are as calcium phosphate granules in cells of the midgut gland (Brachyura), gastroliths (Astacidea and some Brachyura), the haemocoel (some Brachyura) the posterior midgut caeca (Amphipoda) and the ventral portion of the body generally in the Isopoda.5. At ecdysis, the skeleton is shed and the calcium remaining in it is lost from the body.6. Recalcification begins immediately, or shortly after, ecdysis using calcium mobilized from the stores. Simultaneously, or when the stores are exhausted, other sources of calcium are utilized. These are calcium in the water (aquatic species), the food (aquatic and terrestrial species) and the exuviae (chiefly terrestrial species).7. Marine species store little calcium and must obtain the bulk of their requirement (ca. 95%) from the water. Fresh‐water species also store little calcium but have, seemingly, adapted to the lower availability of calcium by increasing the affinity of the calcium‐absorbing mechanism. The rates of uptake of calcium are consequently similar in marine and fresh‐water species.8. A high degree of storage is essential for terrestrial crustaceans as they do not have access to a large aquatic reservoir of calcium. These large reserves enable the animals to reach an advanced stage of calcification, allowing the resumption of foraging and feeding necessary for completion of calcification.9. The control of calcium metabolism during the intermoult cycle is poorly under stood. β Ecdysone appears to control the resorption of calcium and the formation of calcium stores during premoult, but the mechanism of control of calcium metabolism during postmoult and intermoult is unknown.10. The concentration of calcium in the haemolymph of most species is high, but a large proportion of this is in non‐ionized form. In premoult, total calcium levels rise as a result of calcium resorption but little change occurs in the concentration of ionized calcium. Postmoult generally sees a fall in blood calcium, sometimes below the intermoult value.

Étude préliminaire des variations circadiennes des protéines de l'hémolymphe de Penaeus japonicus Bate

The protein contents of the haemolymph in the decapod crustacean Penaeus japonicus Bate exhibit a tricircadian rhythm characterized by two maxima during the night and another one during the day. During the night the total protein concentration in haemolymph is higher in males. Maximal values in males are approximately four times greater (100 mg/ml) than minimal ones (25 mg/ml). Variations are less in females: maximal values are approximately two and a half times higher (75 mg/ml) than minimal ones (30 mg/ml). Electrophoresis in polyacrylamide gradient showed that the different protein constituents in general exhibit similar circadian variations. Time of acrophases depends on the sex and the stage in the intermoult cycle. On the other hand, the mean concentration of each protein constituent calculated from values measured at different times of the day are similar whatever the sex and moulting stage. Between 0 and 6 h certain protein fractions - two in females and one in males - are no longer detectable by electrophoresis. At 12 h, concentration of haemocyanin and its subunits increase simultaneously in both sexes.

The effect of salinity on respiratory metabolism, survival and moulting in the first zoea of Macrobrachium amazonicum (Heller) (Crustacea, Palaemonidae)

Survival, duration of intermoult cycle and respiratory metabolism were evaluated as a function of salinity (0–35‰; 25° C) in early zoeae of the cinnamon shrimp, Macrobrachium amazonicum. Zoeae are extremely resistant to salinity, mortality occurring only in fresh and sea-water after several days. Moulting occurs in all salinities, longer cycles being recorded in 0 and 35‰ S. The metabolism-salinity curve is broadly U-shaped between 0 and 28‰ S but declines sharply in sea-water. Such physiological responses characterise the early zoeae as strongly euryhaline and typically estuarine. Data are discussed in relation to the degree of adaptation of the organism to the freshwater biotope and the position of the species within the generic pattern of adaptive radiation.

Fecampia erythrocephala Giard (Turbellaria Neorhabdocoela), a parasite of the prawn Palaemon serratus Pennant: The adult phase

Since the first description of Fecampia erythrocephala (Caullery and Mesnil, 1903), no other morphological studies have been performed on the species. Observations of adult F. erythrocephala in the prawn Palaemon serratus, a new host for the parasite on the French Atlantic shore, lead to elucidation of the morphology of the species and its evolution inside the cocoon. New data concerning the subepidermal glands, the brain and uterus formation are reported. Observations of spawning confirm the shrinking of the flatworm until it completely vanishes. The storage of the double egg capsules inside a matrix formed by the degenerated epidermis is described. A parasitic influence is noticed on the host's hepatopancreas and on the ovaries of the female prawn. The intermoult cycle is delayed without any apparent morphological changes and the prawn's death does not necessarily follows the exit of Fecampia from the host's body. On account of its fertility, this parasite presents a high risk of contamination for the culture of prawns in Atlantic and Mediterranean marine conditions.

The anal glands of Rhapidostreptus virgator (Diplopoda, Spirostreptidae)

In Rhapidostreptus virgator exocrine gland complexes are found in the anal valves of both sexes. Every gland complex consists of about 200 secretory units, each of which is comprised of four cells: two secretory cells, an intermediary cell, and a canal cell. The amount of secretion produced by these glands varies during the intermoult cycle: it is very small in freshly moulted individuals (postmoult phase), at a medial level during the following intermoult phase, and very large in the premoult phase. The secretion may be used to form the excrement clumps and above all to build the moulting chamber.

Stages of the intermoult cycle in the terrestrial isopod Oniscus asellus and their relation to biphasic cuticle secretion

The intermoult cycle of Oniscus has been divided into 15 stages, recognizable by changes in the appearance of the anterior sternites. The stages are related to concurrent microscopical changes in the integument. The normal stimulus which initiates premoult is followed by a period when no tissue changes are discernible. Apolysis occurs about 7 days after premoult initiation. Thus, use of apolysis to recognize premoult (as in many crustaceans) would result in 44% of premoult passing undetected. Storage of calcium in sternal deposits and the general cuticle of the anterior region during the latter half of premoult is associated with an arrest of cuticle secretion in this region; at the time of posterior ecdysis (Ep) the anterior region has no new exocuticle. The anterior region is thus functionally similar to the decapod gastrolith. Stored calcium is resorbed and the anterior exocuticle secreted during the 24 h following Ep, enabling ecdysis of the anterior region to follow. The accumulation of calcium in the anterior cuticle while the posterior cuticle is undergoing resorption and the secretion of exocuticle at different times in the two regions both imply that the integuments of anterior and posterior regions differ in their responses to the moulting hormone.

Neuroendocrine control of nitrogen metabolism in the Indian field crab oziotelphusa s. senex fabricius—I. End-products and elimination

The literature concerning nitrogenous components and their metabolism in crustaceans has recently been reviewed by Schoffeniels & GiUes (1970). Their review begins with the words, Little information is available on the biochemistry of nitrogenous compounds in arthropods. One could add that virtually nothing is known of the physiology of nitrogen metabolism in crustaceans. Such information as exists has been obtained incidental to studies of osmotic regulation, events of the intermoult cycle and other aspects of growth and development, and oxidative metabolism and energetics. The relatively large amount of work on the metabolism of carbohydrate in crustaceans, reviewed recently by Hohnke & Scheer (1970), has centered on the control of blood sugar concentration, a matter which is of little intrinsic significance in the physiology of these animals. The processes of growth and development (yamaoka & Scheer, 1970) are regulated by the neuroendocrine system, centered in the eyestalks, and the Y-organ or moult gland. Among these processes is a substantial synthesis of protein during the intermoult period, between ecdyses (Renaud, 1949), and the incorporation of labelled amino acids into protein has been studied by Skinner (1965, 1966a,b), Kurup & Scheer (1966), Yamaoka (1974) and Raghavaiah (1977). Evidence that the eyestalks of crustaceans produce factors influencing incorporation of amino acids into protein has been reported by Gorell & Gilbert (1971), McWhinnie & Mohrherr (1970) and Raghavaiah (1977). The present report concerns the effects of extirpation of the eyestalks (ESX) and of administration of extracts of the eyestalks (ESE) on the concentrations of major nitrogenous components of tissues and on the rates of elimination of end-products. ESX is the classical operation of crustacean endocrinology; it removes the X-organ, a neurohaemal organ containing the neuron endings of the neuroendocrine system. It releases the moult gland (Y-organ) from inhibition and thus initiates processes leading to moulting, and

Variations du taux des ecdystéroïdes au cours des cycles de mue et de vitellogenèse chez le Crustacé Amphiphode,Orchestia gammarellus

Ecdysteroid titer in whole extracts of female O. gammarellus varies during the course of the moult cycle: it is minimal at the beginning of the intermoult cycle (stages A, B and Ca) and in D0, and maximal in D2. In hemolymph, the hormone content presents a single peak level in D2; this peak is constituted by ecdysterone, as revealed by HPLC. Ovaries, at the end of vitellogenesis, contain ecdysterone and low polarity substances. Ecdysteroids are also present in eggs after laying. Variations in ecdysteroid levels seem to influence oocyte growth; vitellogenin synthesis, however, is independent of hormonal fluctuations.

Holeuryhalinity and its mechanisms in a cirriped crustacean, Balanus improvisus

Abstract 1. The barnacle Balanus improvisus succeeds in fresh water as well as in sea water. The euryhalinity depends partly on hyperosmotic regulation of the haemolymph and partly on cell volume regulation. 2. The animals osmoconform in waters above 500 mOsm and osmoregulate in more dilute sea waters, showing strict homoiosmoticity below 100 mOsm. Haemolymph and maxillary gland fluid are isosmotic and have equal chloride concentrations. 3. Seventeen free amino acids are found in thorax muscle tissue in amounts varying with haemolymph osmolality. Proline reaches unique values of 0.7 M at hypersaline sea water. 4. The relative water content of muscle tissue varies little with changes in haemolymph osmolality pointing to a regulation of cell volume. The adjustments of the intracellular amino acids, especially proline, assist in this regulation. 5. The intermoult cycle does not significantly influence the measured parameters.

Le cuivre et le zinc chez Cancer irroratus (Crustace: Decapode): Metabolisme compare au cours du cycle d'intermue

1. 1. Variations of copper and zinc content were analysed during the intermoult cycle for Cancer irroratus in the following organs and tissues: exoskeleton, hepatopancreas, hypoderm, gills, hemolymph and muscles. The hemolymph showed the largest copper concentration while the muscles presented the largest zinc content. 2. 2. Except for the muscles, all organs and tissues showed significant ( P<0·01) variations of zinc during the intermoult cycle. Variations of copper content were statistically different ( P<0·01) in any tissue. A significant increase ( P<0·01) of the copper and zinc content took place in the hemolymph during the C4 stage. 3. 3. A correlation—regression analysis between copper, zinc and water content was carried out for each tissue and organ. A positive correlation ( P<0·01) between both metals occurred for the hemolymph, the gills and the hepatopancreas. Hypotheses are proposed to explain such correlations.