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Two small keyhole limpets (Mollusca: Gastropoda: Fissurellidae) were collected live by the senior author and his father (Charles Powell) in the winters of 1967 and 1968 from the side/bottom of moderately flat rocks in the low intertidal zone at Doheny Beach State Park, Dana Point, Orange County, southern California. The larger specimen was collected in the winter of 1968 and the small specimen was collected in winter of 1967. These specimens resemble the genus Lucapinella yet do not quite match any of the known species. The shells are also somewhat similar to Dendrofissurella scutellum from South Africa and two species of Amblychilepas from Australia, however neither of the Dohney Beach specimens can be attributed to those species. This possible new species is assigned to the genus Lucapinella and remains unnamed until additional specimens can be located to determine if they are a new species, a rare exotic species, or a very unusual, miniature L. callomarginata. [ABSTRACT FROM AUTHOR]

The present study provides new documented cases of abnormalities on chitons (hypomerism and coalescence of shell plates), in addition to four new cases on keyhole limpets (closed apical opening), and one new teratologic case on internal organs in octopuses (missing gill). We assess the frequency of these abnormalities and discuss about its possible environmental, mechanic and genetic causes. Several of these findings represent the first of these cases reported in South Pacific Ocean. [ABSTRACT FROM AUTHOR]

Peritrophic membranes ( PMs) are acellular layered structures secreted around ingested materials by the gut epithelium. Most studies on PMs have focused on those of insects and crustaceans due to their potential ability to block the movement of pathogens from ingested materials into the body, and their possible use as unique targets relevant to pest management. While PMs are known to occur in other taxa, their distribution is spotty and little is known about their role in these other species. The gastropod Megathura crenulata produces a true PM, which has a chitinous matrix that makes up nearly half its wet weight. Unlike arthropod PMs, which are released by delamination from the microvilli of their gut cells, the chitinous matrix of the M. crenulata PM is secreted from epithelial cells lining most regions of its gut. Although its mode of synthesis is unique, it may serve the same functions as proposed for other PMs, including regulating diffusion, binding metabolites, restricting protease activity, blocking pathogens, and providing lubrication. In arthropods, numerous proteins with chitin-binding specificities have been identified, consistent with the proposed functions. Analysis of PMs in M. crenulata showed several integral proteins associated with the membrane, suggesting that the PM in this mollusc may be involved in complex functions like those seen in the arthropods. [ABSTRACT FROM AUTHOR]

Oceanographical processes, such as upwelling, induce variations in nutrient availability in marine ecosystems, and evidence indicates that nutrient input can strongly influence the physiological activities, structure, and dynamics of marine communities. Intertidal organisms have long been considered ideal study units in which to quantify the relationship of physical variations and differential energy allocations in specimens that undergo environmental variations, such as observed with nutrient availability. In habitats with differential nutrient input (upwelling versus non-upwelling), both food availability (algae abundance) and seasonal gonadal and foot weight variations were determined in the keyhole limpet Fissurella crassa. Gonadal weight is used as a measure of reproduction allocation whereas foot weight is an indirect indicator of energy allocation towards survival. RNA:DNA ratio in limpets was used as an indicator of biosynthetic capability. Our results indicate that, in general, algae abundance, muscular foot weight, and gonadal weight were higher in upwelling sites during all seasons studied. The same result was found for RNA:DNA ratios. Energetic allocation in animals that inhabit intertidal upwelling habitats supported a constant allocation towards reproduction and soft tissues. In contrast, animals that inhabit non-upwelling habitats showed important energetic restrictions associated with higher water temperature and lower food availability. Our results clearly show that in the keyhole limpet F. crassa food availability is a more important determinant of an individual's condition than a physical variation such as environment temperature. [ABSTRACT FROM PUBLISHER]

Abstract: A liquid chromatography tandem mass spectrometry (LC/MS n ) method for the determination of 12 corticosteroids in bovine liver has been optimized and validated in accordance with the European Commission Decision 2002/657/EC. A bovine liver sample was deconjugated with β-glucuronidase/sulfatase enzyme, extracted with diethyl ether and further cleaned up with Solid Phase Extraction (SPE) before analysis with LC/MS n . Two different enzyme extracts (originating from Helix Pomatia and Keyhole Limpet) and three SPE elution solvents (ethyl acetate, acetonitrile and methanol) were compared during the optimization. Helix Pomatia is generally known as the enzyme most being used for enzymatic hydrolysis purposes. Nevertheless, when detecting corticosteroids in the low μgkg−1 concentration range, the Helix Pomatia extract may lead to interferences in the final LC/MS n chromatogram. When using the Keyhole Limpet enzyme extract, no interferences were observed and therefore, this extract was the best choice for enzymatic hydrolysis tested in this case. Ethyl acetate was used as elution solvent during the validation procedure since SPE elution with acetonitrile resulted in higher chromatographic backgrounds, while elution with methanol showed less reproducible results. Validation of the optimized method was carried out for 10 of the 12 corticosteroids, giving mean recoveries between 91 and 109%, and repeatability and reproducibility coefficients of respectively maximum 13.7 and 18.0%. The working ranges for the linear calibration curves were 5–20μgkg−1 for prednisolone, methylprednisolone and prednisone and 0.5–4μgkg−1 for the other compounds (coefficients of determination R 2 ≥0.97). Specificity, decision limit (CCα) and detection capability (CCβ) were for all compounds within the EC specified limits. [Copyright &y& Elsevier]

Keyhole limpet hemocyanin (KLH) is an immune stimulant derived from a circulating glycoprotein of the marine mollusk Megathura crenulata. We previously reported that KLH inhibited the growth of human Barrett''s-associated esophageal adenocarcinoma in vitro via apoptotic and nonapoptotic mechanisms. We hypothesize that KLH reduces the growth of Barrett''s cancer cells by altering protein expression profiles. A cell line (SEG-1) derived from Barrett''s-associated adenocarcinomas of the distal esophagus was selected. Cells were administered KLH (500 μg/ml) or vehicle. After 24 hours, cytosolic fractions were separated through two-dimensional gel electrophoresis. Statistical analysis was performed with Evolution Pro software to identify spots that were differentially expressed between the KLH and control groups. Proteins displaying a twofold or greater change in expression levels were selected for identification. In a total of 420 spots, 31 were differentially expressed between the KLH and control groups. In all, 12 were upregulated and 19 were downregulated. Of the 31, 17 were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Proteomic evaluation shows downregulation of proteins associated with metabolic processes (glycolysis, protein synthesis). KLH also induced proteins indicative of oxidative stress (heat shock 70 family and UDP-glucose 6-dydrogenase). Our results indicate that growth arrest by KLH is accompanied by a cellular stress response and attenuation of metabolic processes. The use of KLH as adjuvant or topical therapy for Barrett''s adenocarcinoma provides a promising development in the treatment of this disease. [Copyright &y& Elsevier]

Correlation and experimental protocol were used to test the hypothesis that in intertidal and subtidal substrata, the recruitment of the keyhole limpet, Fissurella picta (Gmelin), is determined by the settlement of barnacles. Measurements and experiments made in Metri Bay showed that the abundance of juveniles of F. picta smaller than 20 mm occurs mainly in zones exposed to waves, where barnacle species are dominant. In the intertidal zone, temporal variations in the recruitment of F. picta were positively associated with temporal variations in the recruitment of the barnacle Jehlius cirratus (Darwin). In the subtidal zone, the abundance of F. picta recruits was greater in substrata previously colonized by the barnacle Austromegabalanus psittacus (Molina) than in those colonized by the mussel Mytilus chilensis (Hupé), the most abundant fouling species. These data are added to previous findings that show a decrease in the recruitment of the keyhole limpet in the Mehuín Marine Reserve, where man has been excluded. This in turn has lead to an increase in the populations of a gastropod that has continually diminished the barnacle populations. The results indicate the importance of the variations in the settlement and persistence of barnacle populations in intertidal and subtidal zones for the recruitment of species of high commercial value, such as F. picta.

Correlation and experimental protocol were used to test the hypothesis that in intertidal and subtidal substrata, the recruitment of the keyhole limpet, Fissurella picta (Gmelin), is determined by the settlement of barnacles. Measurements and experiments made in Metri Bay showed that the abundance of juveniles of F. picta smaller than 20 mm occurs mainly in zones exposed to waves, where barnacle species are dominant. In the intertidal zone, temporal variations in the recruitment of F. picta were positively associated with temporal variations in the recruitment of the barnacle Jehlius cirratus (Darwin). In the subtidal zone, the abundance of F. picta recruits was greater in substrata previously colonized by the barnacle Austromegabalanus psittacus (Molina) than in those colonized by the mussel Mytilus chilensis (Hupe), the most abundant fouling species. These data are added to previous findings that show a decrease in the recruitment of the keyhole limpet in the Mehuin Marine Reserve, where man has been excluded. This in turn has lead to an increase in the populations of a gastropod thathas continually diminished the barnacle populations. The results indicate the importance of the variations in the settlement and persistence of barnacle populations in intertidal and subtidal zones for the recruitment of species of high commercial value, such as F. picta. [ABSTRACT FROM AUTHOR]

Analytical dark-field scanning transmission electron microscopy (STEM) of freeze-dried unstained specimens of keyhole limpet henocyanin (KLH: from Megathura crenulata. A prosobranch gastropod) gave a molecular mass of kDa for the subunit of KLH1 and of 345 kDa for the subunit of KLH2, which confirms our published values from SDS/Page. Within the 400-kDa KLH1 subunit we identified, by limited proteolysis, isolation of fragments and N-terminal sequencing, eight distinct 45-60 kDa functional domains (termed 1a through 1h) and determined their sequential arrangement. The KLH1 domains differ biochemically and immunologically from each other and from the previously characterized seven domains of KLH2 (termed 2a through 2g). Our partial amino acid sequences suggest that a domain, equivalent to the C-terminal domain 1h, is missing in KLH2. This deficiency is believed to be genuine and not an artifact of the subunit preparation procedure, since STEM measurements of the native didecamers yielded a mass difference of about 800 kDa between KLH1 and KLH2 (8.3 Mda versus 7.5 Mda), correlating with 20 copies of a financial copies to a functional 1h domain. It was also shown that the KLH1 didecamer can be rapidly split (minutes) into a almost homogeneous population of stable decamers by increasing the pH of the Tris/saline stabilizing buffer (routinely pH 7.4), which contains 5 mM CaCl2 and 5mM MgCl2, to pH 8.5. reformation of the didecamers occurred more slowly (days) upon analysis against the pH7.4 stabilizing buffer leads to the more rapid (overnight) formation of didecamers together with a significant number of previously observed KLH1 multidecamers, which could be structurally distinguished from the established multidecamers of KLH2. [ABSTRACT FROM AUTHOR]