Phospholipids from the hepatopancreas of Indian horseshoe crab Carcinoscorpius rotundicauda

Total phospholipids were extracted from the heart, hepatopancreas, and hemolymph of the Indian horseshoe crab Carcinoscorpius rotundicauda by the conventional method. Characteristic group reaction and 2-dimensional thin-layer chromatography on silica gel were used for identification of different phospholipids. The phospholipid profile obtained from hemolymph and 2 major organs are comparable and show phosphatidyl choline (PC) and phosphatidyl ethanolamine to be the major phospholipids. A phospholipid has been consistently detected migrating immediately below the PC in the thin-layer chromatogram of lipids extracted from the hepatopancreas. When mixed methyl esters of this slower moving PC are resolved on a silica gel plate ran in hexane ether:acetic acid 80:20:1, with appropriate controls, an additional spot is seen just below the normal methyl ester, indicating a difference between the fatty acid compositions of 2 PC (e.g., regular and slower). The slower mixed methyl esters were found to comprise mainly the 4 saturated fatty acids: lauric, myristic, palmitic, and stearic. The slow moving PC seems to consist mainly of molecular species with the above-mentioned saturated fatty acids at both Sn 1 and Sn 2 positions.     

Fertilization in a crab: I. Early events in the ovary,and cytological aspects of the acrosome reaction and gamete contacts

Early events in fertilization were studied in Carcinus maenas by in vitro experiments and ultrastructural analysis; some were found to occur in the lumen of ripe ovaries. The acrosome reaction generally conformed to the usual Reptantia Decapoda pattern. However, a prominent membrane system continuous with the nuclear envelope and located close to the base of the acrosome tubule characterized the type of spermatozoon observed in Carcinus maenas. Such complex anatomical connections linking the three parts of the reacted spermatozoon (acrosome tubule, membrane system and nucleus envelope) may be significant in relation to the membrane system's contribution to the acrosome reaction. The outer layer of the everted acrosomal vesicle was found to comprise tubular elements ending in bell-shaped corpuscles, deeply interdigitated with the oolemma microvilli during the establishment of the initial contacts between the reacted spermatozoon and the egg plasma membrane. At the site of contact, the oolemma formed a minute fertilization cone, locally depressed by the acrosome tubule. During these early fertilization events, the nucleus, like the other spermatozoon components, was seen to penetrate the egg coatings first, and later to be located near the oolemma.     

Histopathological Changes Associated with Shell Disease in the Red King Crab <Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis> (Tilesius, 1815)

Histopathological changes have been revealed associated with shell disease in the red king crab, Paralithodes camtschaticus. The changes in the gills, esophagus, stomach, hepatopancreas, heart, and antennal glands of the crabs are described.     

Urinary excretion of taurine in epilepsy

Evidence that taurine (2-aminoethanesulfonic acid) is related to the epilepsies is supported by work with both experimental animals and hurmans. It may function as a neurotransmitter or modulator of neurotransmission. Investigators using an automated amino acid analyzer reported lower mean urinary taurine excretion among epileptics. However, Rao et al. reported higher taurine excretion among epileptics using an older method. Analyses of the same epileptic and control urines by both methods coupled with paper and molecular size chromatography indicate that substances in addition to taurine are co-eluted with taurine using the older method, yielding spuriously high values. The resolution of this disparity is important because the urinary excretion of taurine may reflect primarily the influence of taurine transport alleles which may be polygenic components in the idiopathic epilepsies.     

Incorporation of ω6 polyunsaturated fatty acids into phospholipids of the crab Carcinus maenas

The incorporation in vivo of ¹⁴C-18:2 ω6 and ³H-20:4 ω6 fatty acids in phospholipids isolated from gills, hepatopancreas and hemolymph of the crab Carcinus maenas was analysed. PC was the most heavily labelled phospholipid from these ω6-unsaturated fatty acids and appeared to play an important part in the phospholipids metabolism in Crustaceans. The pathway of fatty acids synthesis in phospholipids of C. maenas seems to be similar to those described for mammals. It is at the level of tissue Pl of C. maenas that the renewal of the 20:4 ω6 fatty acid is the most important. It is suggested that the rapid reorganization of phospholipid molecular species composition in the crab is checked by deacylation—reacylation cycle.     

Bitter crab syndrome in two species of king crabs from the Sea of Okhotsk

The disease caused by parasitic dinoflagellates of the genus Hematodinium was found in the red Paralithodes camtschaticus and blue P. platypus king crabs from the Sea of Okhotsk. The hemolymph of diseased crabs was cream colored, opaque, and dense. Numerous dinokaryotic trophonts and multinucleate plasmodia of the parasite were revealed in the hemolymph and internals of diseased animals. The parasitic infection was recorded in females and juvenile males from August to mid-October.     

Identification of Bilophila wadsworthia by specific PCR which targets the taurine:pyruvate aminotransferase gene

The bile-resistant, strictly anaerobic bacterium Bilophila wadsworthia is found in human faecal flora, in human infections and in environmental samples. A specific PCR primer set for the gene encoding the first metabolic enzyme in the degradative pathway for taurine in B. wadsworthia, taurine:pyruvate aminotransferase (tpa), was developed and tested. In addition, enrichment cultures were started from faecal samples of primates and felines and shown to contain B. wadsworthia. These were subcultured on agar media and then identified by PCR fingerprinting. PCR for tpa was successful in all positive enrichment cultures and showed no amplification signal in a variety of other bacterial species. Therefore, this PCR method could be a promising tool for rapid detection of B. wadsworthia in biological samples.     

Purification and Some Properties of Two Carboxypeptidases from the Hepatopancreas of the Crab Paralithodes camtschatica

High activity of carboxypeptidases was detected in the hepatopancreas of the crab Paralithodes camtschatica, while aminopeptidase activity in this tissue was low. Two crab carboxypeptidases were purified by chromatography on DEAE-cellulose, phenyl-Sepharose, and Sephadex G-75 to homogeneity. The molecular weight values of carboxypeptidases I and II were 40,000 and 37,000, respectively. The isoelectric point value for both carboxypeptidases was 4.5. The crab carboxypeptidases were activated by NaCl, with maximal activity of carboxypeptidases I and II at 1.0 M and 0.6 M NaCl, respectively. Using 19 N-blocked dipeptides with the general structures Bz-Gly-X and Z-Gly-X, broad substrate specificity of the purified enzymes was demonstrated. Under optimal conditions the values of K _m and k _cat for the hydrolysis of Bz-Gly-l-Phe, Bz-Gly-l-Arg, and Bz-Gly-l-Lys by crab carboxypeptidases were determined. Inhibition data led to classification of the crab enzymes as metallopeptidases. Both carboxypeptidases were stable under neutral and mildly alkaline conditions. In addition, the presence of 1 M NaCl decreased the thermostability of the crab carboxypeptidases. Received August 13, 1999; accepted November 19, 1999.     

Detrimental effects of Ulva lactuca (L.) exudates and low oxygen on estuarine crab larvae

Conventional theory postulates that associations between marine macrophytes and animals are generally positive. This paper presents evidence, however, that a common species of green macroalga, Ulva lactuca (L.), is detrimental to estuarine invertebrates due to the production of toxic exudates and low oxygen tensions which occur in the seaweed beds at night. Bioassays of the responses of zoeae of five species of estuarine crabs (Callinectes sapidus Rathbun, Carcinus maenas L., Eurypanopeus depressus Smith, Neopanope texana savi Smith and Rhithropanopeus harissii Gould), using water in which Ulva lactuca was cultured for 24 h, produced 100% mortality after 22 days. No crabs survived the molt into megalopa. Hypoxic water, 0.5 ± 0.3 ppm oxygen, caused a decline in larval activity (movement), but there was no mortality over an 8-h period, Ulva-water purged to 0.4 ± 0.1 ppm oxygen caused 100% mortality in 13–40 min. These synergistic effects could be critical in estuaries where dense U. lactuca beds cause periods of low dissolved oxygen. We hypothesize larval recruitment may be limited in such systems, particularly in areas where flushing is poor.     

The relationship between sodium and high-affinity taurine uptake in hypothalamic crude P2 synaptosomal preparations

Two uptake systems for taurine transport in a rat hypothalamic crude synaptosomal preparation were identified. The true transport constants were, for the high-affinity uptake system,K _m=240 M andV (maximum velocity)=400 nmol/g protein/min, and for the low-affinity uptake system.K _m=5290 M and V=1640 nmol/g protein/min. The initial velocity of high-affinity taurine uptake by the crude synaptosomal preparation was studied as a function of sodium and taurine concentration. Hill plots were constructed from these data. The requirement of high-affinity taurine uptake on a sodium gradient was examined by utilizing monensin, and the metabolic poisons, 2,4-dinitrophenol and ouabain. The major findings are as follows: 1) One sodium ion is co-transported with each taurine molecule; 2) the high-affinity uptake process is driven by the sodium concentration gradient across the membrane; 3) sodium increases the maximal velocity rather than the affinity of the high-affinity taurine carrier for the taurine molecule; 4) one taurine molecule is transported per carrier for both the high- and low-affinity taurine uptake systems; and 5) high-affinity taurine uptake is an energy-dependent process.     

Age-Related Retinal Degeneration in Animal Models of Aging: Possible Involvement of Taurine Deficiency and Oxidative Stress

There is strong evidence that the retina degenerates with age. Electroretinogram deficits and photoreceptor cell death and structural abnormalities have been observed in both animal and human studies of aging. The mechanism behind this phenomenon is a very interesting area for scientific and medical study. Current data support the link between retinal degeneration and increased oxidative stress. Taurine is a free amino acid found in high millimolar concentrations in the retina, and age-related deficiency in retinal levels of taurine may contribute to the retinal degeneration associated with age. Taurine acts as an antioxidant and taurine replenishment is known to alleviate oxidative stress in the retina. Thus taurine supplementation may be useful in the treatment of age-related retinal dysfunction.     

Important crab resources inhabiting Hokkaido waters

In this paper the fishing grounds, fluctuations in catches, history of exploitation, classification, distribution, migration, life history and resource trends of the edible crabs of the waters around Hokkaido are discussed. The Hokkaido crab fisheries developed along with the canning industry and there is now an increasing demand for boiled crab. At first, the most popular species was the king crab, Paralithodes camtschatica, but as its numbers declined other species such as the horsehair crab, Erimacrus isenbeckii, the banasaki crab, Paralithodes brevipes, the snow crab, Chionoecetes opilio, and the red snow crab, Chionoecetes japonicus, became popular. This report is based on the results of the latest research into the ecology and resources of the Erimacrus isenbeckii and Paralithodes brevipes species, which are currently the focus of resource conservation in Hokkaido.