Search results for "mollusca"
showing 10 items of 125 documents
In situ recordings of large gelatinous spheres from NE Atlantic, and the first genetic confirmation of egg mass of Illex coindetii (Vérany, 1839) (Ce…
2021
AbstractIn total, 90 gelatinous spheres, averaging one meter in diameter, have been recorded from ~ 1985 to 2019 from the NE Atlantic Ocean, including the Mediterranean Sea, using citizen science. More than 50% had a dark streak through center. They were recorded from the surface to ~ 60–70 m depth, mainly neutrally buoyant, in temperatures between 8 and 24°C. Lack of tissue samples has until now, prohibited confirmation of species. However, in 2019 scuba divers secured four tissue samples from the Norwegian coast. In the present study, DNA analysis using COI confirms species identity as the ommastrephid broadtail shortfin squid Illex coindetii (Vérany, 1839); these are the first confirmed …
Stratigraphical ranges of tegulated inoceramid bivalves in the type area of the Maastrichtian Stage (Belgium, the Netherlands)
2018
Abstract Recently collected material, in fine- to medium-grained biocalcarenites and in coeval flint nodules, of the tegulated inoceramid taxa Spyridoceramus tegulatus (von Hagenow, 1842) and Tenuipteria argentea (Conrad, 1858) from various members of the Gulpen Formation and the overlying Maastricht Formation allows their stratigraphical ranges to be refined. It is concluded that the ranges correspond closely to those in east-central Poland (Vistula [Wisla] River valley region), where S. tegulatus occurs in the lower Maastrichtian and lower upper Maastrichtian ( Endocostea typica , Trochoceramus radiosus and ‘ Inoceramus ’ ianjonaensis inoceramid zones, or Belemnella occidentalis and Belem…
Molecular evolution of the arthropod hemocyanin superfamily.
2001
Arthropod hemocyanins are members of a protein superfamily that also comprises the arthropod phenoloxidases (tyrosinases), crustacean pseudohemocyanins (cryptocyanins), and insect storage hexamerins. The evolution of these proteins was inferred by neighbor-joining, maximum-parsimony, and maximum-likelihood methods. Monte Carlo shuffling approaches provided evidence against a discernible relationship of the arthropod hemocyanin superfamily and molluscan hemocyanins or nonarthropodan tyrosinases. Within the arthropod hemocyanin superfamily, the phenoloxidase probably emerged early in the (eu-)arthropod stemline and thus form the most likely outgroup. The respiratory hemocyanins evolved from t…
Protein mapping of calcium carbonate biominerals by immunogold
2007
The construction of metazoan calcium carbonate skeletons is finely regulated by a proteinaceous extracellular matrix, which remains embedded within the exoskeleton. In spite of numerous biochemical studies, the precise localization of skeletal proteins has remained for a long time as an elusive goal. In this paper, we describe a technique for visualizing shell matrix proteins on the surface of calcium carbonate crystals or within the biominerals. The technique is as follows: freshly broken pieces of biominerals or NaOCl then EDTA-etched polished surfaces are incubated with an antibody elicited against one matrix protein, then with a secondary gold-coupled antibody. After silver enhancement,…
ASPECTS OF THE ECOLOGY AND NATURAL HISTORY OF PARAERGASILUS RYLOVI (COPEPODA, ERGASILIDAE) PARASITIC IN UNIONIDS OF FINLAND
2004
The distribution of Paraergasilus rylovi in 17 populations of unionids was investigated. In 1 unionid population, the parasite was studied regarding host age, size, sex, and the reproductive period (occurrence of egg sacs). Results from pooled material from the years 1987--1989 and 1996 (southern Finland, 11 populations) indicated that Anodonta piscinalis (n = 1,359) is the main host (total mean prevalence 71% and intensity +/-SE of infection 16.4+/-0.6). Pseudanodonta complanata (n = 106) was infected occasionally (3% and 1.3+/-0.3), whereas Unio pictorum (n = 108) and U. tumidus (n = 17) were not infected. Results from 17 A. piscinalis populations showed that P. rylovi occurs in southern …
Finding of Parastrongylus cantonensis (Chen, 1935) in Rattus rattus in Tenerife, Canary Islands (Spain).
2010
Parastrongylus cantonensis is a parasite of murid rodents that can infect humans and cause health problems as eosinophilic meningitis. Although it is endemic in south Asia, the Pacific islands, Australia, USA, and a few Caribbean islands, it has been extended to new geographical regions. In the Canary Islands (Spain) a survey of helminths of Rattus rattus, Rattus norvegicus and Mus musculus domesticus was carried out. Furthermore, five species of molluscs were examined for nematode larvae to determine whether they are potential intermediate hosts of P. cantonensis. Nematodes were found in the lungs of 15% of 67 R. rattus examined in Tenerife, one of the four studied islands, with a prevalen…
Repetitive DNAs in the slug Milax nigricans: association of ribosomal (18S–28S and 5S rDNA) and (TTAGGG)n telomeric sequences) in the slug M. nigrica…
2003
Spermatocyte chromosomes of the slug Milax nigricans (Mollusca: Gastropoda: Pulmonata) were studied using silver staining (Ag-NOR) and fluorescent in situ hybridization (FISH) with four repetitive DNA probes [18S rDNA, 5S rDNA, (TTAGGG)n and (GATA)n]. Silver impregnation was inadequate to localize the chromosome sites of nucleolus organizer regions (NORs) since no silver dots occurred on the chromosomes at spermatogonial metaphase and a diffuse silver stainability could be observed on the bivalents at metaphase-I. Unlike silver staining, single-colour rDNA FISH consistently mapped major ribosomal sites (18S-28S rDNA) on two small-sized chromosomes in spermatogonial cells and on the correspo…
Organometallic complexes with biological molecules. XVIII. Alkyltin(IV) cephalexinate complexes: synthesis, solid state and solution phase investigat…
2004
Abstract Dialkyltin(IV) and trialkyltin(IV) complexes of the deacetoxycephalo-sporin-antibiotic cephalexin [7-( d -2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid] (Hceph) have been synthesized and investigated both in solid and solution phase. Analytical and thermogravimetric data supported the general formula Alk 2 SnOHceph · H 2 O and Alk 3 Snceph · H 2 O (Alk=Me, n -Bu), while structural information has been gained by FT-IR, 119 Sn Mossbauer and 1 H, 13 C, 119 Sn NMR data. In particular, IR results suggested polymeric structures both for Alk 2 SnOHceph · H 2 O and Alk 3 Snceph · H 2 O. Moreover, cephalexin appears to behave as monoanionic tridentate ligand coordinating th…
Spermiogenesis in the vermetid gastropod Dendropoma petraeum (Gastropoda, Prosobranchia)
2002
The structure and maturation of the male gonad of the Mediterranean vermetid gastropod Dendropoma petraeum are described. Histological sections of the gonads were made throughout development and gonad activity was monitored at regular monthly intervals. During the autumn months the gonad is very small and is surrounded by a large quantity of connective tissue; it becomes more voluminous from December to August, with the highest growth peak in springtime. The stages of spermatogenesis were also observed and described.
Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells
2015
Intricate biomineralization processes in molluscs engineer hierarchical structures with meso-, nano-, and atomic architectures that give the final composite material exceptional mechanical strength and optical iridescence on the macroscale. This multiscale biological assembly inspires new synthetic routes to complex materials. Our investigation of the prism-nacre interface reveals nanoscale details governing the onset of nacre formation using high-resolution scanning transmission electron microscopy. A wedge polishing technique provides unprecedented, large-area specimens required to span the entire interface. Within this region, we find a transition from nanofibrillar aggregation to irregu…