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| | 1. |
2006 May 16 |
Evidence for a clade composed of molluscs with serially repeated structures: Monoplacophorans are related to chitons
Giribet, Okusu, Lindgren, Huff, Schrödl, Nishiguchi
Proc Natl Acad Sci U S A 2006 May 16;103(20):7723-7728.
Abstract
Monoplacophorans are among the rarest members of the phylum Mollusca. Previously only known from fossils since the Cambrian, the first living monoplacophoran was discovered during the famous second Galathea deep-sea expedition. The anatomy of these molluscs shocked the zoological community for presenting serially repeated gills, nephridia, and eight sets of dorsoventral pedal retractor muscles. Seriality of organs in supposedly independent molluscan lineages, i.e., in chitons and the deep-sea living fossil monoplacophorans, was assumed to be a relict of ancestral molluscan segmentation and was commonly accepted to support a direct relationship with annelids. We were able to obtain one specimen of a monoplacophoran Antarctic deep-sea species for molecular study. The first molecular data on monoplacophorans, analyzed together with the largest data set of molluscs ever assembled, clearly illustrate that monoplacophorans and chitons form a clade. This “Serialia” concept may revolutionize molluscan systematics and may have important implications for metazoan evolution as it allows for new interpretations for primitive segmentation in molluscs.
[Pubmed: 16675549]
| | 2. |
2001 Jan 1 |
The effects of sedimentation and light on recruitment and development of a temperate, subtidal, epifaunal community.
Maughan BC
J. Exp. Mar. Biol. Ecol. 2001 Jan 1;256(1):59-71.
Abstract
Sedimentation has often been implicated as a factor in structuring epifaunal assemblages on hard substrata yet there are few studies that empirically test this relationship. This study investigated the effects of light and sedimentation conditions on the initial recruitment and subsequent development of an encrusting community at Lough Hyne, S.W. Ireland. Slate settlement panels were subjected to four different conditions of sedimentation and light. The five replicates of each treatment were photographed at approximately 6-week intervals over 13 months. Values for Brillouin diversity (HB) and number of recruits were greatest for shaded panels sheltered from sediment. Number of species was much higher on downward facing panels relative to upward facing panels, regardless of conditions of sedimentation and light. Sedimentation resulted in reduced cover for some species, such as Lithothamnion spp., whilst others, such as Anomia ephippium, were less affected by this variable. Total space occupied was significantly higher for inverted panels, possibly indicating geotaxic behaviour of some larvae. Number of species on each panel condition was more similar for sets of panels exposed for shorter periods relative to the 13-month experiment, implying that post-settlement mortality may differ between treatments.
[Pubmed: 11137505]
| | 3. |
2011 Nov 17 |
An Efficient Method for Genomic DNA Extraction from Different Molluscs Species
Pereira, Chaves, Bastos, Leitão, Guedes-Pinto
Int J Mol Sci 2011 Nov 17;12(11):8086-8095. published online before print
Abstract
The selection of a DNA extraction method is a critical step when subsequent analysis depends on the DNA quality and quantity. Unlike mammals, for which several capable DNA extraction methods have been developed, for molluscs the availability of optimized genomic DNA extraction protocols is clearly insufficient. Several aspects such as animal physiology, the type (e.g., adductor muscle or gills) or quantity of tissue, can explain the lack of efficiency (quality and yield) in molluscs genomic DNA extraction procedure. In an attempt to overcome these aspects, this work describes an efficient method for molluscs genomic DNA extraction that was tested in several species from different orders: Veneridae, Ostreidae, Anomiidae, Cardiidae (Bivalvia) and Muricidae (Gastropoda), with different weight sample tissues. The isolated DNA was of high molecular weight with high yield and purity, even with reduced quantities of tissue. Moreover, the genomic DNA isolated, demonstrated to be suitable for several downstream molecular techniques, such as PCR sequencing among others.
[Pubmed: 22174651]
| | 4. |
2012 Apr 5 |
Drilling Predation on Serpulid Polychaetes (Ditrupa arietina) from the Pliocene of the Cope Basin, Murcia Region, Southeastern Spain
Martinell, Kowalewski, Domènech
PLoS One 2012 Apr 5;7(4). published online before print
Abstract
We report quantitative analyses of drilling predation on the free-living, tube-dwelling serpulid polychaete Ditrupa arietina from the Cope Cabo marine succession (Pliocene, Spain). Tubes of D. arietina are abundant in the sampled units: 9 bulk samples from 5 horizons yielded ∼5925 specimens of D. arietina. Except for fragmentation, tubes were well preserved. Complete specimens ranged from 3.1 to 13.4 mm in length and displayed allometric growth patterns, with larger specimens being relatively slimmer. Drilled Ditrupa tubes were observed in all samples. Drillholes, identified as Oichnus paraboloides, were characterized by circular to elliptical outline (drillhole eccentricity increased with its diameter), parabolic vertical profile, outer diameter larger than inner diameter, penetration of one tube wall only, narrow range of drill-hole sizes, and non-random (anterior) distribution of drillholes. A total of 233 drilled specimens were identified, with drilling frequencies varying across horizons from 2.7% to 21% (3.9% for pooled data). Many tube fragments were broken across a drillhole suggesting that the reported frequencies are conservative and that biologically-facilitated (drill-hole induced) fragmentation hampers fossil preservation of complete serpulid tubes. No failed or repaired holes were observed. Multiple complete drillholes were present (3.9%). Drilled specimens were significantly smaller than undrilled specimens and tube length and drill-hole diameter were weakly correlated. The results suggest that drillholes were produced by a size-selective, site-stereotypic predatory organism of unknown affinity. The qualitative and quantitative patterns reported here are mostly consistent with previous reports on recent and fossil Ditrupa and reveal parallels with drilling patterns documented for scaphopod mollusks, a group that is ecologically and morphologically similar to Ditrupa. Consistent with previous studies, the results suggest that free-dwelling serpulid polychaetes are preyed upon by drilling predators and may provide a viable source of data on biotic interactions in the fossil record.
[Pubmed: 22496828]
| | 5. |
1970 |
[Biochemical analysis of the calcified byssus of Anomia ephippium L. (bivalve mollusca)].
Pujol JP, Bocquet J, Tiffon Y
Calcif Tissue Res. 1970;5(4):317-26.
[Pubmed: 5469611]
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