Pelecypod Molluscs Research Articles

Caffeine (1,3,7-Trimethylxanthine) as a modulator of Arsenic bioaccumulation in the experimental Pelecypod model, Lamellidens corrianus

Aims: The present investigation was carried out to study modulator effect of caffeine (1,3,7-Trimethylxanthine) on Arsenic-induced alterations on freshwater bivalve, Lamellidens corrianus. Materials and Methods: Freshwater Pelecypod Mollusc, L. corrianus were exposed to acute dose of arsenic (0.672 ppm As 3+ ) for 4 days. Arsenic exposed Bivalves were allowed to cure naturally and with caffeine. Testis and digestive glands from different groups were removed and dried in the oven. The dry powders were digested in nitric acid and perchloric acid in 4:1 ratio at hot temperature till dryness. The digest was dissolved in double glass distilled water and the arsenic contents were estimated by the Atomic Absorption Spectrophotometer. Results: After 4 days of exposure, the amount of bioaccumulated arsenic in the testis and digestive glands was 1.044 and 1.119 μg/g. During the recovery after 4 days, the bioaccumulated arsenic was reduced to 0.969 and 1.067 μg/g of normal water while in caffeine exposed Bivalves was reduced to 0.917 and 0.975 μg/g in testis and digestive glands respectively. Conclusion: Rapid reduction in the arsenic contents in caffeine exposed Bivalves indicates the role of caffeine in arsenic excretion. Therefore, the caffeine (1,3,7-Trimethylxanthine) as a modulator of Arsenic bioaccumulation in the experimental Pelecypod model, L. corrianus

First record of Monobrachium parasitum Mereschkowsky, 1877 (Cnidaria: Hydrozoa) from Brazil, in the tropical southwestern Atlantic, and its implication for bipolarity concepts

Project HABITATS was recently initiated in the Campos Basin (20.5–24° S), state of Rio de Janeiro, to assess biological impacts of petroleum exploration and exploitation on the continental shelf and slope of Brazil. Among species discovered in benthic samples from the area is the hydroid Monobrachium parasitum Mereschkowsky, 1877, occurring in an epibiotic association with the pelecypod mollusc Mendicula ferruginosa (Forbes, 1844): this is the first report of an association between the two species. Monobrachium parasitum has always been reported from cold waters, and is generally considered bipolar. This report records the occurrence of M. parasitum at lower latitudes, where they have seldom been collected: it is also the first account of this species from South America and the southwestern Atlantic. Moreover, the bathymetric distribution of M. parasitum is extended to a depth of 998 m. No previous records exist of hydroids from the Brazilian continental slope.

Characterization of a novel octopamine receptor expressed in the surf clam Spisula solidissima

We have cloned and sequenced a cDNA from the surf clam ( Spisula solidissima, a pelecypod mollusc) that encodes an octopamine receptor which we have named Spi-OAR. The sequence of Spi-OAR shares many similarities with two Aplysia and three Drosophila octopamine receptors belonging to a sub-group of β-adrenergic-like octopamine receptors. Using an expression vector and transient transfections of Spi-OAR into HEK 293 cells, we observed an increase of cAMP upon addition of octopamine and, to a lesser extent, of tyramine, but not after addition of dopamine, serotonin, or histamine. Using a battery of known agonists and antagonists for octopamine receptors, we observed a rather unique pharmacological profile for Spi-OAR through measurements of cAMP. Spi-OAR exhibited some constitutive activity in HEK 293 cells and no Ca 2+ responses could be detected following addition of octopamine to Spi-OAR-transfected cells. RT-PCR analysis revealed ubiquitous expression of Spi-OAR mRNA in all adult tissues, oocytes and early embryos examined. While addition of serotonin to isolated clam oocytes resulted in meiotic activation, similar additions of octopamine had no effect, suggesting that its potential role in clam reproductive physiology differs significantly from that of serotonin. This work identifies Spi-OAR as a novel mollusc octopamine receptor closely related to other invertebrate β-adrenergic-like octopamine receptors, with possible reproductive and other physiological functions. This initial characterization of Spi-OAR makes possible further investigations and comparisons with more studied and familiar insect or gastropod mollusc octopamine receptors.

Testing hypotheses concerning the formation of shell growth marks in marine pelecypods

This paper reviews the evidence supporting the current hypotheses (daily, tidal, endogenous, and other rhythms of growth) accounting for short-term periodicity in the formation of marks (external growth ridges and internal growth increments) on the shell of marine pelecypod molluscs. With few exceptions our analysis shows too much unexplained variability and the availability of too few studies of potential sources of variation for the proposed cycles of mark formation (circadian, circatidal) to be accepted. Since shell deposition takes the form of marks, which must be discrete in frequency (0, 1, or 2 per given day or tidal period), we submit that individual frequencies must be used to test hypotheses concerning the rhythms of shell growth mark formation, and we propose the use of three criteria: (i) that departure of the individual measured frequency from the expected frequency should not be more than the maximal error in measurements (maximal counting errors made by the observer); (ii) should condition one be violated, then the so-called "missing" or "superfluous" marks should be clearly accounted for; (iii) that potential sources of variation (e.g., age, habitat, locality, season) should not significantly influence the frequency of formation of the marks.

Pharmacologically induced stereotyped locomotory movements in the pelecypod mollusc, Anodonta Cygnea

1. Bathing freshwater mussels in water containing ergotamine or methylergometrine induced rhythmic coordinated movements of the foot and shell maintained in a stereotyped form for hours. The effect was weak at 10 −9mol/1, moderate to strong at 1–4 × 10 −8 mol/1, and irreversible to lethal at 5–8 × 10 −8 mol/1. 2. Bathing mussels in serotonin (10–20 μmol/1) induced similar movements. They closely correspond to the well-known digging cycles exhibited by pelecypod molluscs during burrowing locomotion. 3. The serotonin content of central ganglia was not changed significantly in mussels exhibiting the ergot-induced locomotory movements. Ergotamine, up to 10 −5−10 −6 mol/1, did not affect the spontaneous and evoked liberation of serotonin, as well as the serotonin uptake. There is thus little indication of any direct influence of ergots on serotonergic mechanisms.

Herpes-type virus diseases of marine organisms

SynopsisHerpesviruses and viruses having the typical morphological and replicative characteristics of the genusHerpesvirusfrom marine animals have been reviewed. These animals include one teleost fish, two reptiles, one pelecypod mollusc and an arthropod. With the exception of the arthropod, all descriptions of virus-related diseases were from animals maintained under artificial culture conditions and a common theme relates temperature, stress and crowding to outbreaks of disease. The significance of these observations in relation to the possible evolution of the herpesvirus group is discussed.

Stability of free amino acid levels in stressed Abarenicola pacifica.

A change in the composition of the free amino acid (FAA) pool of pelecypod molluscs under stress has been described. This response consists of a significant decrease in the level of glycine, while the taurine level remains constant, leading to a decrease in the total free amino acid level and a decrease in the glycine:taurine ratio. It has been suggested that this alteration in FAA composition may be useful as an indicator of physiological stress in a wide variety of invertebrates. This suggestion has been tested by exposing a burrowing polychaete, Abarenicola pacifica, to sediment artificially contaminated with Prudhoe Bay crude oil (PBC).

Some Phylogenetical Aspects on the Occurrence of Somatostatin in the Gastro-Entero-Pancreatic Endocrine System

Rodioimmunoassayable somatostatin (SRIF) was found in acid ethanol extracts from various parts of the gastro-entero-pancreatic (GEP) endocrine system in reptiles, amphibians, teleost bony fish, cartilaginous fish, and jawless fish, as well as in a deuterostomian invertebrate, the tunicate, Ciona intestinalis. The cellular sites could, as a rule, be easily visualized light-microscopically by the peroxidase-anti-peroxidase (PAP) immunocytochemical procedure, using guinea-pig and rabbit antisera against synthetic SRIF. The standard Hellerström-Hellman technique, used to detect argyrophi SRIF-storing D cells, failed to visualize the SRIF cells in teh GEP endocrine system of the tumicate and of the jaw-less fish. Moreover, the results comfirmed the previous description that this technique only exceptionally (and sometimes only after further modifications) gave positive results when applied to the GEP endocrine system of bony fish, amphibians, and reptiles. In cartilaginous fish, however, it worked adequately and confirmed the radio-immunological and immunocytochemical observations. In the mucosa of the alimentary tract and in the parenchyma of its associated glands of one echinoderm and two pelecypod molluscs and one crustacean arthropod no sgns of the occurrence of SRIF-storing cells were observed using the three correlated procedures. In several of these tissues, signs of the occurrence of insulin-producing cells had perviously been observed. Thus, SRIF seems to appear at a later evolutionary stage than insulin. The principal islets (Brockmann corpusles) of the marine teleost fish, Cottus scorpius, had the highest concentrations of radioimmunoassayable SRIF of all the GEP organs and tissues investigated, viz. about 200 ng/mg wet weight. Nevertheless, it was only 1/5 of the actual insulin content.

Delayed mortality following thermal stress in three species of intertidal pelecypod molluscs (Modiolus demissus, Mya arenaria, and Mytilus edulis)

Determination of delayed mortality following thermal stress in three species of intertidal pelecypod molluscs (Modiolus demissue, Mya arenaria, and Mytilus edulis) shows that substantial mortality may occur for some considerable interval following removal of a potentially lethal thermal stress. In general, delayed mortality is greater in short-term bioassays (< 96 h) than in long-term bioassays (> 96 h). Moreover, the extent of delayed mortality is evident much earlier in bioassays lasting less than 12 h than in longer bioassays.These observations are discussed in relation to the determination of levels of safety for environmental pollutants.

A rapid technique for recording sizes of juvenile pelecypod molluscs

The production of the principal mariculture organisms started with the seaweeds in China rather than shrimp and fish. This is because the seaweeds are autotrophic and have relatively simple life histories whereas the shrimp and fish are heterotrophic and have complicated life histories. The mollusks are in the middle; they are heterotrophic but many of them are plankton feeders and have simple life histories. Thus, up to 1983, Japanese kelp still led in the mariculture production at 231 300 tons, and total seaweed production, at 241 300 tons, exceeded that of mollusks, at 239 000 tons of which 114 500 tons was mussels. We may well call this the “seaweed era” in Chinese mariculture. In 1986, however, mariculture of the mussel led the production, at 210 700 tons against 203 400 tons of Japanese kelp, and total mollusk production was 438 000 tons, occupying 51% of the total mariculture production. We are, therefore, in the “mollusk era” at present. Fish and shrimp should be the leading products of mariculture and this era will definitely come.In old China the seaweeds, mollusks, shrimp and fish were cultivated under traditional methods which were very inefficient, and in 1950 total production was only 10 000 tons. In the traditional methods, natural “seeds”, including spat and fry, were employed. These, however, were entirely at the mercy of nature. Artificial “seeds” were first employed in seaweeds. In 1952, the Japanese kelp, Laminaria japonica, was cultivated with sporelings grown from spores collected on artificial substrate. This was followed by the cultivation of purple laver, Porphyra spp. commercialized in 1963, mussels, Mytilus galloprovincialis, in 1972, the local scallop, Chlamys farreri, in 1973, the shrimp, Penaeus chinensis in 1979, and the bay scallop, Argopecten irradians, in 1985.

Effects of Bottom Substrate on the Brackish Water Bivalve Rangia cuneata

The effect of bottom sediment composition on the pelecypod mollusc,Rangia cuneata, was investigated in the Pamlico River estuary, North Carolina. Mortality, meat weight: shell weight ratio, and shell growth were evaluated in relation to particle size, organic matter concentration, and phosphate concentration in the sediment.In situ factorial experiments were carried out for 5 months using indivdually marked clams placed in boxes of predetermined sediment composition. Clay-silt sediments were found to be an unfavorable environmental substrate. The detrimental effect was greater in sediments containing high levels of organic matter and phosphate, suggesting that physical and chemical factors associated with finer sediments were responsible. However, in sand sediments, high levels of organic matter and phosphate were found to be favorable toRangia.

Ciliocincta sabellariae gen. and sp. n., an Orthonectid Mesozoan from the Polychaete Sabellaria cementarium Moore

An orthonectid parasitizing the sabellariid polychaete Sabellaria cementarium Moore has been studied with the aid of a method of impregnation with activated silver albumose (Protargol). This technique differentiates the boundaries of many of the cells, and also brings out the kinetosomes of cilia, thereby permitting a precise analysis of the pattern of ciliation. In adult individuals, the cells of the outer jacket are arranged in rings around the axial mass. Certain of the jacket cells are characterized by presence of conspicuous granules and at least one transverse row of cilia, whereas others have neither obvious granules nor cilia. In both sexes, the first three rings of jacket cells bear three transverse rows of cilia; all other ciliated cells have either one row of cilia near the posterior margins or a row near both the anterior and posterior margins. In typical males, there are 26 or 27 rings, of which rings 6, 10, 12, 15, 17, 20, and 22 are unciliated. In typical females, there are 36 or 37 rings, of which rings 6, 8, 10, 12, 14, 16, and 18 are unciliated. In the male, the mass of gametes or prospective gametes occupies the posterior half of the axial mass. In the female, there is a column of 9 to 12 oocytes occupying the posterior four-fifths of the axial mass. The name Ciliocincta sabellariae gen. n., sp. n. is proposed for this orthonectid. The type locality is near Dot Rock (long 122047.8/ W; lat 48?29.5' N), San Juan Archipelago, Washington. Of 88 worms of the host species examined from this locality, only two (both males) were infected. The few known species of orthonectid mesozoans are parasites of acoel, rhabdocoel, and polyclad turbellarians, nemerteans, polychaete annelids, gastropod and pelecypod molluscs, and ophiuroid echinoderms. Except for one report of an orthonectid parasitizing a nemertean collected near Woods Hole, Massachusetts (Meinkoth, 1956), all published accounts deal with species occurring in the Mediterranean Sea or in the Atlantic waters of Europe. That these interesting organisms will eventually be found in a variety of hosts in North America and elsewhere may confidently be predicted, but attempts to find them on the Pacific coast in invertebrates of the same taxonomic groups as those which they are known to parasitize have until recently been unsuccessful. My discovery of orthonectids, at the Friday Harbor Laboratories of the University of Washington, came about in a nearly fortuitous manner. On 14 July 1962 I collected a large number of brittle stars (Ophiura sarsi) with a view to examining them for orthonectids. After disReceived for publication 31 August 1964. 37 secting over 80 specimens with negative results, I liberated the rest of the catch. Returning to the laboratory, I decided to examine a few specimens of the polychaete Sabellaria cementarium Moore (Sabellariidae) which had been collected on the same dredging trip. From previous experience, I knew that this species was regularly infected by a so-called schizogregarine of the genus Selenidium. As the first worm was opened, hundreds of male and female orthonectids emerged from the tissue of the body wall. Over a period of several days, I examined a total of 88 worms (47 males, 41 females) from the same locality. The sixtysixth specimen to be opened also was infected. Both of the parasitized worms were mature males carrying sperm, and before examination appeared to be completely normal. The orthonectid from S. cementarium, for which I propose the name Ciliocincta sabellariae gen. n., sp. n., resembles certain species of Rhopalura. However, its precise pattern of ciliation is decidedly different from that described by any of the European investigators. It is possible that if the morphology of other This content downloaded from 207.46.13.114 on Thu, 26 May 2016 06:30:46 UTC All use subject to http://about.jstor.org/terms 38 THE JOURNAL OF PARASITOLOGY, VOL. 51, NO. 1, FEBRUARY 1965 orthonectids were investigated carefully, some of them would be found to have an organization similar to that of C. sabellariae. The type locality for C. sabellariae is near Dot Rock (long 122o47.8' W; lat 48?29.5' N), San Juan Archipelago, Washington. The material was collected at a depth of 7 fathoms. Syntype slides have been deposited in the United States National Museum (USNM No. 23734).

Glycogen of Mactra

GLYCOGENS, branched chain polymers of glucose containing α-1,4-glycoside bonds in the main chains and α-1,6-glycoside bonds at the branch points, have been identified in the tissues of all animals thus far examined1. These polymers are made up of a single kind of sub-unit bonded together by a single type of bond and thus only relatively small differences in the glycogens from different species have been found. The most important difference is in the average chain-length of the molecule, which is inversely related to its degree of branching. This measurement describes quite well the main features of the glycogen molecule, and is therefore of interest to the student of comparative biochemistry. The glycogen of Mactra had not been previously characterized; and this communication describes some of the properties of the compound isolated from this pelecypod mollusc.

Validity of Concentric Rings of Mya arenaria, L. for Determining Age

CERTAIN students of molluscan growth, among whom may be mentioned Weymouth1, have succeeded in demonstrating the annual character of particular concentric rings on the valves of several pelecypod molluscs.