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At least 307 records · Page 17Linked to original sources
PubMed2002

First confirmation of human diarrhoeic poisonings by okadaic acid esters after ingestion of razor clams (Solen marginatus) and green crabs (Carcinus maenas) in Aveiro lagoon, Portugal and detection of okadaic acid esters in phytoplankton.

A new outbreak of human diarrhoeic poisonings (DSP) with esters of okadaic acid (OA) was confirmed after ingestion of razor clams (Solen marginatus) harvested at Aveiro lagoon (NW Portugal) in the summer of 2001. Accumulation of marine toxins in second order consumers was investigated in the edible parts of a shellfish predator abundant at Aveiro lagoon, the green crab Carcinus maenas. Okadaic acid was found, also in a predominant esterified form. Levels in edible parts (comprising mainly viscera) surpassed 16microg/100g. We suggest that one patient may have developed profuse diarrhoea after ingestion of a large number of green crabs contaminated with okadaic acid esters. At least 32microg OA/100g were found in a remaining sample of its meal. Domoic acid was also found but under the allowable level in force in USA of 30microg/g crab viscera. In cooked crabs, significant losses of domoic acid were found and it is not suspected to have contributed to the poisoning event, although being a vector for this toxin. The low percentage of free okadaic acid found is in accordance with a predation predominantly on benthonic shellfish (razor clams, clams and common cockle) rather than on rock mussels. These last ones present usually higher percentages of free okadaic acid. Okadaic acid was confirmed with full-scan mass spectra either in plankton and mussel extracts. Okadaic acid esters were also found in plankton extracts. Percentages between 40-60% of esterified OA were found in samples freshly extracted. Ester's percentage diminished drastically if after sonication the extract was kept at room temperature. The major part of the esters was water-soluble.

Adult↗
PubMed1978

Histochemical studies on the morphology of the Golgi apparatus and its relation to catecholamine biosynthesis in the locus coeruleus of Rhesus and crab-eating monkeys.

Detailed histochemical studies have been conducted on the distribution of thiamine pyrophosphatase (TPPase), L-gulonolactone oxidase (GLO), and NAD-linked xylitol dehydrogenase (XDH) in every component of the Locus coeruleus (LC) of healthy adult male Rhesus and crab-eating monkeys in order to clearify the morphology of the Golgi apparatus (GA) and its relation to biosynthesis of catechol-amines in this special nucleus of the primate (NA nucleus A 6 as defined in the Rhesus monkey by German and Bowden [1975]). Medium-sized neurons of both species of monkeys, which are considered to play an important role in the LC, were classified into 5 groups on the basis of morphological patterns of the GA. Many neurons of both species of monkeys were positive for the XDH test while some neurons of the crab-eating monkey as well as a few neurons of the Rhesus monkey were positive for the GLO reaction. The LC of both species of monkeys must be composed of metabolically one kind of identical medium-sized parasympathetic neurons whose GA may continously undergo 5 distinct phasic changes depending on the functional state of that cell. However, the GA changes its shape much more significantly even within each group of the 5 in the crab-eating monkey than in the Rhesus monkey. The GA Type IV may correspond to the catabolic phase of the GA during which biosynthesis of both catecholamines and vitamin C should be going on. Production of vitamin C may greatly help biosynthesis of catecholamines in LC. The difference in species is evident between the 2 kinds of monkeys studied in regard to the degree of their ability to synthesize these substances. The degree of the ability to synthesize vitamin C parallels the density distribution of Type IV neurons in LC whose GA often develops much more greatly in the crab-eating monkey than in the Rhesus monkey.

Alcohol Oxidoreductases↗
PubMed2003

Breeding biology of the intertidal sand crab, Emerita (Decapoda: Anomura).

Emerita is a burrowing mole crab or sand crab, adapted to life in wave-washed sandy beaches of temperate and tropical seas. The reproductive biology of this anomuran crab presents several peculiarities, all contributing to its adaptation to this harsh environmental niche. We discuss the following aspects: 1) sex ratio and size at sexual maturity, 2) neoteny and protandric hermaphroditism, 3) mating behaviour and sperm transfer strategy, 4) synchronisation of moulting and reproduction, 5) environmental impact on reproductive cycle and egg production, 6) biochemistry of yolk utilisation and energetics, 7) larval development, dispersal and settlement and 8) the value of Emerita as indicator species. These aspects are discussed in the light of the life history pattern, comprising a sedentary adult and pelagic larval phases. The successful colonisation of the physically challenging habitat of the sandy beach by Emerita is attributable largely to reproductive strategy and the larval developmental and recruitment pattern. Sensitivity to changing environmental conditions, including pollution, make this intertidal crab an indicator species for monitoring anthropogenic impact.

Animals↗
PubMed2001

Flux of heavy metal accumulation in various organs of the intertidal marine blue crab, Portunus pelagicus (L.) from the Kuwait coast after the Gulf War.

The metal levels of arsenic, chromium, copper, lead, magnesium, manganese, selenium, vanadium, and zinc concentrations were determined in various body organs, viz., hepatopancreas, gills, gonad, gastric stomach, and muscle of the blue crab, Portunus pelagicus (Crustacea: Decapoda) to assess the bioaccumulation of metals associated with petroleum input a decade after the 1991 Gulf War oil spillage. Sample solutions prepared were analyzed using an atomic absorption spectrophotometry. High concentrations of Zn and Cu in the muscle and hepatopancreas tissues were a strong indicative of high exposure of P. pelagicus to these metals. However, muscle tissue had been found to accumulate the highest values for all metal speciations analyzed. Copper, zinc, and chromium in samples collected from Station II covering the Kuwait City area were often in excess of those present in Station I and III. Arsenic, lead, magnesium, manganese, selenium, and vanadium were greater in individuals obtained from Station I. A significant correlation was found to exist between Se and V in crab muscle with a surge in Se metal concentration, which was found to be inversely proportional to that of V metal concentration irrespective of the sex of the crab. The difference in patterns of metal occurrence and the significant increase in the Cu and Zn concentrations in various organs of the crab were largely associated with the 1991 Gulf War oil spill. Such results could be used as a baseline for the monitoring of the level of metals in marine organisms of future studies.

Animals↗
PubMed2002

Role of a copper-specific metallothionein of the blue crab, Callinectes sapidus, in copper metabolism associated with degradation and synthesis of hemocyanin.

We have identified three MT encoding genes in the blue crab: MT-I, inducible by cadmium, zinc and copper; MT-II, inducible by cadmium and zinc; and MT-III, inducible by copper only [Syring et al., Comp. Biochem. Physiol. C, 125 (2000) 325-332]. To examine the role of the CuMT-I and CuMT-III isoforms in copper metabolism associated with the synthesis and degradation of the oxygen-binding copper protein, hemocyanin, we (1) cloned and sequenced hemocyanin cDNA, (2) examined interaction of the CuMTs with endoplasmic reticulum (ER) vesicles and (3) measured changes in levels of hemocyanin, MT-I, MT-III protein and mRNA that occur in crabs during different stages of the molt cycle. The cDNA-derived hemocyanin amino-acid sequence revealed the presence of a leader peptide indicating that hemocyanin is a secretory protein that is synthesized on the ER. Copper uptake studies show that ER vesicles take up both Cu1+ and Cu2+ in an ATP-independent process. The copper transporter has a Km of 10.8+/-2.4 microM copper and a Vmax of 6.1+/-0.5 nmol Cu/mg protein/10 min. ER vesicles contain hemocyanin, and bind CuMT-I and, preferentially, CuMT-III. However, binding does not result in copper transfer to the ER. There are statistically significant changes in hepatopancreas MT-III and hemocyanin mRNA, and in hemolymph hemocyanin concentrations during the molt cycle. MT-I mRNA remains constant. Changes in MT-III mRNA are positively correlated with changes in hemocyanin mRNA and hemocyanin protein, which points to coordinate control of MT-III and hemocyanin transcription. No CuMT-III protein is observed in hepatopancreas of intermolt crabs when levels of both MT-III and hemocyanin mRNA are high, suggesting rapid utilization of copper bound to MT-III when cells are actively synthesizing hemocyanin. CuMT-III is present in premolt and softshell crabs, and its emergence appears to coincide with a decrease in hemocyanin synthesis and increase in hemocyanin degradation. These results support the hypothesis that the copper-specific metallothionein is intricately involved in copper homeostasis associated with both the synthesis and degradation of hemocyanin.

Amino Acid Sequence↗
PubMed2001

Variability in the edible fraction content of 60Co, 99Tc, 110mAg, 137Cs and 241Am between individual crabs and lobsters from Sellafield (north eastern Irish Sea).

We investigated the variability of anthropogenic radionuclide content of the edible fractions of individual edible crabs (Cancer pagurus L.) and European lobsters (Homarus gammarus L.) caught commercially in the Sellafield offshore area. Sixteen female and 18 male crabs and 20 female and 17 male lobsters were selected from commercial catches made between 25 May and 5 June 1997. Each gender group was selected to be within the known weight range for commercially caught crustacea from the area. Four artificial radionuclides (60Co, 110mAg, 137Cs or 241Am) were detected by gamma-spectrometry. The edible fraction content of these radionuclides between males and females for either species were not statistically significantly different. 99Tc was analysed by chemical separation and beta-counting. 99Tc concentrations in female crabs tended to be higher (172 +/- 205 (16) Bq kg-1(wet); mean +/- standard deviation (n samples)) than those in males (85 +/- 58 (18) Bq kg-1 (wet)), although this was not a statistically significant difference. For both male and female crabs, 99Tc concentrations tended to decrease with increasing whole live weights. For 99Tc in lobsters the picture is less clear. Female lobsters contained more activity (14800 +/- 7400 (20) Bq kg-1 (wet)) than males (7100 +/- 3900 (17) Bq kg-1 (wet)). The results were used to discuss the implications for sampling and monitoring.

Animals↗
PubMed1996

Salinity effects on cadmium accumulation in various tissues of the tropical fiddler crab Uca rapax.

Pollution of water and sediments by industrial discharges of heavy metals, mainly cadmium (Cd), threatens the biota of mangrove ecotones around the mouth of the Tuy river, in northern-central Venezuela. Short-term lethal Cd concentrations were determined in adult male Uca rapax collected from a clean site and kept in 75% seawater (SW). The 96-h LC50 obtained, 380 micromol (=43 mg) Cd liter(-1), is remarkably higher than values previously reported for other crustacean, mollusc or fish species. Tissue accumulation of Cd was examined in crabs acclimated to 125, 75 or 25% SW and exposed to sublethal CdCl2 levels ranging from 9.0 to 225 micromol liter(-1) (i.e. 1.0-25 mg Cd liter(-1)). The metal contents of carapace, gills, hepatopancreas, muscle and hemolymph rose pronouncedly at the highest concentration tested and particularly in the crabs treated in dilute (=25%) SW. In the latter, analyses of the relative distribution of whole-body Cd burden showed that about 80% is in the carapace, 2.4% in the gills, 4% in hepatopancreas, 3% in muscle, 9.3 in other viscerae, 1% is bound to the dried solids of hemolymph and ca. 0.2% appears to be in solution in this fluid. Exposure of crabs to Cd in dilute SW enhances the rates of entry or uptake of the metal, possibly mediated by Ca2+ transport mechanisms, and may exceed the detoxifying capacity of organs such as the hepatopancreas. Thus, Cd may be more harmful to crab populations experiencing frequent fluctuations of ambient salinity, such as are usual in mangrove swamps.

Journal Article↗
PubMed2002

Drinking and osmoregulation in the mangrove crab Ucides cordatus following exposure to benzene.

In benzene-exposed Ucides cordatus acclimated for 96 h to 9 and 34 per thousand SW, haemolymph, urine and gastric juice are isosmotic with each other, but differ significantly in osmolality from external media. In both salinities, under benzene action, urine K+ excretion and calcium absorption are increased significantly, whereas Na+ absorption and Mg2+ excretion show U/B ratios similar to control values. In 9 per thousand SW, some ionic exchanges via benzene-exposed gills are possibly hastened. Benzene exposure decreases significantly branchial chamber water osmolality, [Na+] and [K+], whereas [Ca2+] and [Mg2+] are unaffected. However, faster medium exchange presumably occurs in 34 per thousand SW, both crab groups show branchial chamber water osmotic and ionic concentrations similar to surrounding medium. Benzene exposure unaffected gastric juice composition. In both media, [Ca2+] and [Mg2] accumulate several times higher than surrounding media, and [Na+] and [K+] are significantly hypo-ionic to haemolymph. Na+ and K+ G/H ratios are lower in crabs acclimated to 34 per thousand SW than in crabs acclimated to 9 per thousand SW. Drinking rates are enhanced by benzene exposure and are higher at 34 per thousand SW than in seawater isosmotic with the haemolymph (26 per thousand SW). Benzene exposure affects significantly osmoregulatory capability, slowing haemolymph dilution after transfer to clean 9 per thousand SW. Lower haemolymph dilution rate accounts for higher osmolality, but 48 h after transfer there is no recovery like in control crabs. Haemolymph transfusion experiments suggest an interaction among effects of benzene and hormonal factors, possibly on water influx.

Animals↗
PubMed2000

Inhibition kinetics of green crab (Scylla serrata) alkaline phosphatase activity by dithiothreitol or 2-mercaptoethanol.

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme which catalyzes the nonspecific hydrolysis of phosphate monoesters. Some pollutants in seawater affect the enzyme activity causing loss of the biological function of the enzyme, which affects the exuviating crab-shell and threatens the survival of the animal. The present paper studies the effects of thiohydroxyal compounds on the activity of green crab alkaline phosphatase. The results show that thiohydroxyal compounds can lead to reversible inhibition. The equilibrium constants have been determined for dithiothreitol (DTT) and mercaptoethanol (ME) binding with the enzyme and/or the enzyme-substrate complexes. The results show that both DTT and ME are non-competitive inhibitors. The kinetics of enzyme inactivation by ME at low concentrations has been studied using the kinetic method of the substrate reaction. The results suggest that at pH 10.0, the action of ME on green crab ALP is first quick equilibrium binding and then slow inactivation. The microscopic rate constants were determined for inactivation and reactivation. The rate constant of the forward inactivation (k(+0)) is much larger than that of the reverse reactivation (k(-0)). Therefore, when the ME concentration is sufficiently large, the enzyme is completely inactivated.

Alkaline Phosphatase↗
PubMed2001

Comparison of metallothionein concentrations and tissue distribution of trace metals in crabs (Pachygrapsus marmoratus) from a metal-rich estuary, in and out of the reproductive season.

Crabs, Pachygrapsus marmoratus, were sampled in June 1997 and February 1998 from two sites (at the mouth and 25 km upstream) in the metal-rich Gironde estuary, France. Gills and hepatopancreas were analysed for metal (Cd, Cu, Zn) and metallothionein (MT) contents, in order to examine the influence of both biological and environmental factors on the physico-chemical forms of detoxified metal storage in the crabs. The concentrations of MT and both cytosolic and insoluble metals were not greatly different between males and females, and the influence of organ weights was also minimal. Intersite differences were observed, probably resulting from the gradient of salinity in the estuary, which interacts with both the chemical speciation and bioavailability of metals, and the general protein metabolism of the crabs. Seasonal changes were also important, probably in interaction with the moult and reproductive cycles. In February, concentrations of insoluble metals were generally higher than in June, in both organs, suggesting that essential metals, particularly Zn, are stored during winter then remobilised during the breeding season. The natural variability in the concentrations of MT often concealed any relationship with accumulated metal concentrations. Thus MT in crabs cannot be considered as a useful biomarker of metal pollution.

Animals↗
PubMedDate not supplied

Interactions of local movement detectors enhance the detection of rotation. Optokinetic experiments with the rock crab, Pachygrapsus marmoratus.

Walking crabs move their eyes to compensate for retinal image motion only during rotation and not during translation, even when both components are superimposed. We tested in the rock crab, Pachygrapsus marmoratus, whether this ability to decompose optic flow may arise from topographical interactions of local movement detectors. We recorded the optokinetic eye movements of the rock crab in a sinusoidally oscillating drum which carried two 10-deg wide black vertical stripes. Their azimuthal separation varied from 20 to 180 deg, and each two-stripe configuration was presented at different azimuthal positions around the crab. In general, the responses are the stronger the more widely the stripes are separated. Furthermore, the response amplitude depends also strongly on the azimuthal positions of the stripes. We propose a model with excitatory interactions between pairs of movement detectors that quantitatively accounts for the enhanced optokinetic responses to widely separated textured patches in the visual field that move in phase. The interactions take place both within one eye and, predominantly, between both eyes. We conclude that these interactions aid in the detection of rotation.

Animals↗
PubMedDate not supplied

Binocular interaction in the optokinetic system of the crab Carcinus maenas (L.): optokinetic gain modified by bilateral image flow.

We recorded optokinetic eye movements of the crab, Carcinus maenas, in split-drum experiments. The patterns were either oscillated in antiphase on both sides mimicking translational image flow or they were oscillated in phase producing rotational image flow. Eye movements elicited by the rotational stimulus were larger than those produced by the pseudotranslational pattern movements. The smaller response to the latter is mainly a consequence of binocular interaction, the strength of which depends on both the phase-shift and amplitude of pattern oscillation. We develop two hypotheses to explain our results: either (1) signals from each eye modify the gain of the linkage signals coming from the other eye, or (2) the signals coming from the other eye modify the gain of the control loop itself. Quantitative evaluation of the data favors the second of these two hypotheses, which comprises the models of Barnes and Horridge (1969) and Nalbach et al. (1985). In addition, we found that it is the signals from the two slow channels of the crab's movement-detecting system that are transferred from one eye to the other, while signals of the fastest channel act almost exclusively ipsilaterally. We discuss our results as an adaptation by which an animal with panoramic vision compensates exclusively the rotational component of image flow during locomotion. The fact that freely walking crabs distinguish the two components of image flow better than restrained crabs indicates that further visual and nonvisual signals help to disentangle image flow.

Adaptation, Physiological↗
PubMedDate not supplied

Local mechanisms for the separation of optic flow-field components in the land crab, Cardisoma guanhumi: a role for motion parallax?

Although a number of global mechanisms have been proposed over the years that explain how crabs might separate the rotational and translational components of their optic flow field, there has been no evidence to date that local mechanisms such as motion parallax are used in this separation. We describe here a study that takes advantage of a recently developed suite of computer-generated visual stimuli that creates a three-dimensional world surrounding the crab in which we can simulate translational and rotational optic flow. We show that, while motion parallax is not the only mechanism used in flow-field separation, it does play a role in the recognition of translational optic flow fields in that, under conditions of low overall light intensity and low contrast ratio when crabs find the distinction between rotation and translation harder, smaller eye movements occur in response to translation when motion parallax cues are present than when they are absent. Thus, motion parallax is one of many cues that crabs use to separate rotational and translational optic flow by showing compensatory eye movements to only the former.

Adaptation, Physiological↗
PubMed1983

Degradation of collagen substrates by a trypsin-like serine protease from the fiddler crab Uca pugilator.

The collagenolytic properties of a trypsin-like protease from the hepatopancreas of the fiddler crab Uca pugilator have been examined. All collagen types, I-V, were attacked by this enzyme. Types III and IV were degraded much more rapidly than types I, II, and V. Crab protease produced multiple cleavages in the triple helix of each collagen at 25 degrees C; only in the case of type III collagen, however, was a major cleavage observed at a 3/4:1/4 locus that corresponded to the region of collagen susceptibility to mammalian collagenase action. Additionally, both the affinity and the specific activity of the crab protease for native collagen were lower than those which characterize mammalian collagenase. The results of this study, in conjunction with a previous report on the collagenolytic activity of another serine protease from the fiddler crab [Welgus, H. G., Grant, G. A., Jeffrey, J. J., & Eisen, A. Z. (1982) Biochemistry 21, 5183], suggest that the following properties distinguish the action of these invertebrate collagenolytic enzymes from the metalloenzyme collagenases of mammals: (1) broad substrate specificity, including both noncollagenous proteins and collagen types I-V; (2) ability to cleave the native triple helix of collagen at multiple loci; (3) reduced affinity or higher Km for collagen; and (4) lower specific activity on collagen fibrils.

Animals↗
PubMed2001

Chlorinated cyclodiene pesticide residues in blue mussel, crab, and fish in the Gulf of Gdańsk, Baltic Sea.

Chlordane components (CHLs) and their metabolites (heptachlor, cis-heptachlor epoxide, U82, MC4, trans-chlordane, MC5, cis-chlordane, MC7, oxychlordane, MC6- and trans- and cis-nonachlor) and aldrin, dieldrin, endrin, isodrin, endosulfan 1, endosulfan 2, and mirex were quantified in the soft tissues of blue mussel, a whole crab, and whole fishes collected from the spatially different sites in the Gulf of Gdańsk. Six to twelve chlordane compounds and metabolites and dieldrin were detected in all organisms examined while aldrin, endrin, isodrin, endosulfans 1 and 2, and mirex were not found above the detection limit of the method. The lipid weight based concentrations in Baltic biota were relatively small and ranged from 12 to 150 and 7.6-77 ng/g, while between 0.16 and 6.8 and 0.10-6.6 ng/g in fresh tissue, respectively. The profile (%) of chlordane compounds was very similar between various fish species with trans-nonachlor (28 +/- 17), cis-chlordane (23 +/- 18), oxychlordane (13 +/- 7), and heptachlor epoxide (11 +/- 5) as major constituents and was totally different in crab with oxychlordane as the most dominating (>65%) compound. Blue mussel, lamprey, and three-spined stickleback exhibited a smallest ability to metabolize CHLs, and such fishes as cod, lesser sand-eel, sand-eel, pikeperch, perch, round goby, flounder, and herring showed a slightly better ability, while crab was able to effectively metabolize most of CHL compounds except trans-nonachlor. A value of the quotient of the trans-nonachlor to cis-chlordane concentrations (N/C quotient) was 1.0 in blue mussel, 3.1 in crab, and between 0.9 and 1.8 in fish. Both the small concentrations of CHLs in all organisms and the values of N/C quotients close to 1 imply on a long-range aerial transport through movement of the air masses from the remote regions of the northern hemisphere as a main source of this pesticide in the Gulf of Gdańsk. The interdependences between the CHL profiles for various fish species and between different sampling sites were examined using the principal component analysis (PCA) method. Applying the PCA model the first four significant components explained 90% (43% + 23% + 15% + 8%) of the total variance in the data matrix.

Animals↗
PubMed2002

Assessment of chlorinated dibenzo-p-dioxin and dibenzofuran trends in sediment and crab hepatopancreas from pulp mill and harbor sites using multivariate- and index-based approaches.

Mill process changes and source controls instituted in the late 1980s at pulp and paper mills along the British Columbia (BC) coast produced dramatic reductions in both the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and the TEQ (2,3,7,8-TCDD toxic equivalents). Nevertheless, questions remained as to whether the sediments were acting as contaminant sources or sinks, whether crab uptake pathways have stayed the same since the mills ceased producing PCDD/Fs, and whether improvement was faster at some sites than others. To examine the processes governing the changes in PCDD/F composition, PCDD/F sources and compositional trends for the coastal BC sites were interpreted using sediment and crab PCA (principal components analysis) models and two indices based on the three main groups of PCDD/Fs that covary in all PCA models. One index measured the relative inputs of chlorine bleaching PCDFs and PCP (pentachlorophenol)-related PCDDs at each mill and harbor site whereas the other measured the relative inputs of PCP wood preservatives and pulp mill effluents. Results indicated that PCDFs produced during chlorine bleaching accumulate from sediments to crabs more readily than the PCDDs but that the chlorine bleaching TCDFs have generally decreased in importance at all mill sites. In the years just before 1995, little change was observed in either the proportion of toxic 2,3,7,8-chlorinated congeners or the PCDD/F concentrations, and the improvements seemed to have largely ceased by 1995. The lack of change in PCA composition for the harbors provided a further, disturbing indication that ecosystem recovery may have stalled. Results also implied that the main route of PCDD/Fs into crabs shifted from uptake via a pelagic food web incorporating effluent-borne PCDD/Fs associated with suspended particulate matter to uptake via a benthic food web.

Animals↗
PubMed2003

Female sex pheromone-mediated effects on behavior and consequences of male competition in the shore crab (Carcinus maenas).

Exposure to receptive female pheromone elicits guarding behavior in shore crab males (Carcinus maenas), but little is known about the effects of sex pheromone on male competition or if the female plays an active role in mate choice. This study examined whether female pheromone enhanced agonistic behavior between males and what effects visual and chemical cues had on the rules and costs of such contests. We also investigated whether females exhibit a preference for males in terms of size. Under laboratory conditions, solitary male shore crabs engaged males who already had possession of a female. The visual and chemical presence of a receptive female had an impact on contest rules and costs. Fights were costly in terms of duration and of sustaining injury with either one or both crabs incurring injury in 40% of fights. To investigate the metabolic consequences of fighting over a perceived sexual resource (chemical cue only), fights were staged between pairs of size-matched males in the presence of water containing the female sex pheromone, water in which males had been kept, and untreated seawater. The duration and intensity of contests were greater when staged in the presence of the female pheromone compared with the two other treatments. Crabs that fought in the presence of female sex pheromone also had a greater accumulation of L-lactate and a reduction of glycogen stores. Fights were less costly in terms of injury with a single chemical cue compared with enhanced costs with a multiple sexual cue. The importance of female choice was determined by presenting postmolt females with different sized males. Males were kept in a fixed position, and the majority of females approached and performed courtship behavior to the largest males, demonstrating that females may be selective in terms of size.

Aggression↗
PubMedDate not supplied

[Isolation and primary structure of trypsin from the red king crab Paralithodes camtschaticus].

Trypsin from hepatopancreas of the Paralithodes camtschaticus crab was isolated in homogeneous state by successive ion-exchange chromatography on DEAE-Sephadex, affinity chromatography on Agarose modified with peptide ligands from trypsin hydrolysate of salmin, and ion-exchange chromatography on a Mono Q column. The total yield of the protein was 64%. Its N-terminal amino acid sequence was determined (IVGGTEVTPG-). A sample of amplified total cDNA of hepatopancreas of king crab was obtained. The cDNA fragment containing the complete coding part of the gene was isolated on the basis of the known N-terminal amino acid sequence of the mature form of the trypsin. The polypeptide chain of the proenzyme consists of 266 aa. The mature trypsin involves 237 aa, which corresponds to its molecular mass of 24.8 kDa. A comparison of the amino acid sequence of the king crab trypsin with those of trypsins from other species of crustaceans demonstrated their high structural homology. The trypsin from the Penaeus vannamei shrimp appeared to be the most close in its primary structure to that of the king crab (70% identity).

Amino Acid Sequence↗