Bioaccessibility of heavy metals in rapa whelk Rapana venosa (Valenciennes, 1846): Assessing human health risk using an in vitro digestion model

Instead of total metal concentration measurements in seafood, bioaccessibility is a more important parameter for human health risk assessment. Therefore, bioaccessibility of Cd, Cr, Cu, Mn, Ni, Pb, and Zn in the edible soft tissues of rapa whelk (Rapana venosa Valenciennes, 1846) collected along the southern Black Sea coast were investigated using an in vitro digestion model. Zn was detected at the highest concentration, whereas Ni was the lowest for total metal concentrations. Total Cd and Pb concentration in the tissues were found to be higher than maximum permissible limits set by European Commission. The bioaccessibility of metals in the tissues was found to be decreased in the order: Cu (77.11%) > Cd (70.13%) > Zn (64.52%) > Ni (61.27%) > Pb (50.53%) > Cr (43.41%) > Mn (22.59%). While significant positive linear regressions were observed between the total and bioaccessible concentrations for Mn, Pb, and Ni, significant negative linear regressions were found for Cd in the tissues (p < 0.05). The hazard quotients (HQ) calculated using bioaccessible heavy metal amount were detected lower than the limit value (HQ < 1), which may not pose a potential hazard to humans declared by US Environmental Protection Agency. However, the consumption of rapa whelk may cause a potential risk concerning human health for the Cd and Pb levels in case of increased serving sizes and portions.     

A challenging insight on the structural unit 1 of molluscan Rapana venosa hemocyanin

Hemocyanins of mollusks are high molecular mass glycoproteins with a complex quaternary structure which still remains to be defined in detail for most of its species as far as number, spatial distribution and interactions of their structural units is concerned. In the present study, we isolated the functional units of the structural subunit RvH1 of Rapana venosa hemocyanin, combining enzymatic and non-enzymatic methods. Our results suggest that Hc's carbohydrate moieties play a basic role in the organization of the structural units, resulting from post-translational polymerization of the 50 kDa functional units and involving sugar moieties that link between them.     

Seasonal variations in biochemical composition during the reproductive cycle of the veined rapa whelk Rapana venosa (Valenciennes, 1846) from the northern coast of China

Seasonal variations in the biochemical composition of Rapana venosa in relation to reproductive cycle and environment on the northern coast of China were investigated from March 2012 to February 2013. The results indicated that R. venosa has an annual reproductive cycle with synchronized gonad development in both females and males. Gametogenesis was initiated in September and gametes developed slowly during the winter, followed by rapid gonad development during spring and summer. Most individuals from this study were sexually mature between May and June, and gamete release occurred mainly between May and August. The peak of spawning was found in July and the recovery of the gonad was observed between August and November. The key biochemical components including glycogen, protein and lipid were analysed in four tissues, specifically the gonad, digestive gland, mantle and foot. The declining glycogen content in the gonad, digestive gland and mantle during maturation suggested that glycogen was consumed during the development of the gonad. Lipids and protein can be stored in the digestive gland and used during the winter in a period of food shortage. The protein and lipid contents in the ovaries increased during gonad development, which suggested that the protein and lipid had been accumulated as vitellin in oocytes.     

Antimicrobial proline-rich peptides from the hemolymph of marine snail Rapana venosa

Hemolymph of Rapana venosa snails is a complex mixture of biochemically and pharmacologically active components such as peptides and proteins. Antimicrobial peptides are gaining attention as antimicrobial alternatives to chemical food preservatives and commonly used antibiotics. Therefore, for the first time we have explored the isolation, identification and characterisation of 11 novel antimicrobial peptides produced by the hemolymph of molluscs. The isolated peptides from the hemolymph applying ultrafiltration and reverse-phase high-performance liquid chromatography (RP-HPLC) have molecular weights between 3000 and 9500 Da, determined by mass spectrometric analysis. The N-terminal sequences of the peptides identified by Edman degradation matched no peptides in the MASCOT search database, indicating novel proline-rich peptides. UV spectra revealed that these substances possessed the characteristics of protein peptides with acidic isoelectric points. However, no Cotton effects were observed between 190 and 280 nm by circular dichroism spectroscopy. Four of the Pro-rich peptides also showed strong antimicrobial activities against tested microorganisms including Gram-positive and Gram-negative bacteria.     

Isolation and characterization of polymorphic microsatellite and COI loci from the whelk Kelletia kelletii

There is considerable interest in the genetic structure of Kelletia kelletii because of its economic, ecological and scientific importance. To that end, we developed species-specific primers which amplify mitochondrial cytochrome c oxidase subunit I as well as 13 hypervariable nuclear microsatellite loci. Using dye-labelled primers, the microsatellite loci can be co-amplified in two multiplex polymerase chain reactions and scored simultaneously on an automated sequencer.     

Consumption rates and prey preference of the invasive gastropod Rapana venosa in the Northern Adriatic Sea

The alien Asian gastropod Rapana venosa (Valenciennes 1846) was first recorded in 1973 along the Italian coast of the Northern Adriatic Sea. Recently, this predator of bivalves has been spreading all around the world oceans, probably helped by ship traffic and aquaculture trade. A caging experiment in natural environment was performed during the summer of 2002 in Cesenatico (Emilia-Romagna, Italy) in order to estimate consumption rates and prey preference of R. venosa. The prey items chosen were the Mediterranean mussel Mytilus galloprovincialis (Lamarck 1819), the introduced carpet clam Tapes philippinarum (Adams and Reeve 1850), both supporting the local fisheries, and the Indo-Pacific invasive clam Anadara (Scapharca) inaequivalvis (Bruguière 1789). Results showed an average consumption of about 1 bivalve prey per day (or 1.2 g wet weight per day). Predation was species and size selective towards small specimens of A. inaequivalvis; consumption of the two commercial species was lower. These results might reduce the concern about the economical impact on the local bivalve fishery due to the presence of the predatory gastropod. On the other hand, selective predation might probably alter local community structure, influencing competition amongst filter feeder/suspension feeder bivalve species and causing long-term ecological impact. The large availability of food resource and the habitat characteristics of the Emilia-Romagna littoral makes this area an important breeding ground for R. venosa in the Mediterranean Sea, thus worthy of consideration in order to understand the bioinvasion ecology of this species and to control its likely further dispersal.     

基于线粒体ND1和COI基因序列探讨锯眼蝶亚科主要类群的系统发生关系

测定了分布于中国的锯眼蝶亚科4族10属共20个种的线粒体ND1和COI基因的部分序列,结合从GenBank中获得的4个国外种类的同源序列,以凤蝶科的迪洛尔娟凤蝶(Allancatria deyrolle)、丝带凤蝶(Sericinus montela),以及娟蝶科的西猛娟蝶(Parnassius simonius)为外类群,通过邻接法、最大简约法、最大似然法和贝叶斯法重建了分子系统树,分析了该亚科内主要类群的系统发生关系。分析结果表明:帻眼蝶族和锯眼蝶族具有较近的亲缘关系;黛眼蝶族不是单系群,该族中的黛眼蝶属、荫眼蝶属与眉眼蝶族具有较近的亲缘关系,带眼蝶属、藏眼蝶属、毛眼蝶属和帕眼蝶属聚合为一个独立的支系,其中带眼蝶属和藏眼蝶属在所有的分析方法中均以100%的置信度(BP=100%,PP=1.00)相聚合,建议将它们合并为一属。     

Phylogeny of the green lacewing Chrysoperla nipponensis species‐complex (Neuroptera: Chrysopidae) in China,based on mitochondrial sequences and AFLP data

Abstract Several studies have indicated that the green lacewing, Chrysoperla nipponensis (Neuroptera: Chrysopidae) may include more than one valid species. We investigated the phylogenetic status of Chrysoperla nipponensis s.l. in China and Japan using mitochondrial sequences and AFLP data. The molecular phylogenetic analyses based on mitochondrial genes showed that the C. nipponensis species‐complex comprises four clades, each having high support values. In addition, the phylogenetic tree based on AFLP data indicates that the species‐complex comprises three groups. These results confirm that C. nipponensis s.l. comprises at least three genetically distinct clades and suggests that two of these clades may be closely related to populations of C. nipponensis in Japan. However, these clades cannot be recognized as species until analysis of their courtship songs has been completed.     

Neuropeptides regulate the cardiac activity of a prosobranch mollusc,Rapana thomasiana

Summary Involvement of neuropeptides in the regulation of cardiac activity in a prosobranch mollusc, Rapana thomasiana, was studied physiologically as well as immunohistochemically. A catch-relaxing peptide (CARP) showed strong inhibitory effects on the heart with a lower threshold than acetylcholine. The action of CARP was in contrast to that of another neuropeptide, FMRFamide, which has previously been shown to enhance the heart beat. Benzoquinonium blocked the effects of acetylcholine and stimulation of right cardiac nerves 1 and 3b, but not those of CARP, suggesting that the effects of nerve stimulation are mainly due to the release of acetylcholine. Immunohistochemical examinations demonstrated that FMRFamide-like and CARP-like immunoreactive neurons are distributed in the visceral ganglia. Although a neuron appeared to show weak immunoreactivity to both antisera, evidence for the coexistence of peptides in a single neuron was not exhibited. Positive immunoreactivity to FMRFamide and CARP antisera also appeared in right cardiac nerves 1 and 3. In the heart, FMRFamide- and CARP-like immunoreactive fibers were restricted to the atrium and the aortic end of the ventricle, consistent with the morphological observation of innervation. The present results suggest that FMRFamide- and CARP-like peptides are involved in regulating the heart beat.     

A new skink species (Oligosoma taumakae sp. nov.; Reptilia: Scincidae) from the Open Bay Islands,New Zealand

Abstract

We describe a new skink species (Oligosoma taumakae sp. nov.) from the Open Bay Islands, New Zealand. This species is diagnosed on the basis of several morphological characteristics, and its specific status is supported by mitochondrial sequence data (ND2, ND4). The new species appears to be most closely related to O. acrinasum, O. infra‐punctatum, O. otagense and O. waimatense. The new taxon appears to be rare and endemic to the island of Taumaka in the Open Bay Islands (off the west coast of the South Island). Predation by a flightless rail (weka, Gallirallus australis), native to New Zealand but introduced to the Open Bay Islands, is a major conservation concern.     

Successful worldwide invasion of the veined rapa whelk, <Emphasis Type="Italic">Rapana venosa</Emphasis>, despite a dramatic genetic bottleneck

Biological invasions represent an important component of global change, with potentially huge detrimental effects on native biological biodiversity and ecosystems. Knowledge about invasion history provides information about the invasion process and the origin and genetic composition of invading populations. To clarify the source and invasive routes of a successful world-wide invader, the veined rapa whelk, Rapana venosa, genetic variability of samples from five representative native populations from coasts of Japan and China and 13 worldwide invasive populations was analyzed using 11 nuclear microsatellite loci. A dramatic decrease of genetic variation was detected in the invasive populations compared with the native populations. The results demonstrated that R. venosa was capable of establishing itself in many areas despite a dramatic genetic bottleneck, suggesting that a remarkable reduction of genetic diversity is not a limiting factor for short-term success of this invasive species. Considering the lack of mitochondrial variation previously observed in the invasive populations, the dramatic genetic bottleneck and the allele distribution detected using microsatellites suggested that the original introduced Black Sea population could have been founded by very few individuals, perhaps only a single female and a single male. The initial invasive Black Sea population was likely an accidental introduction from Japan, and then invaded the Adriatic Sea by range expansion, which served as a source for subsequent invasive populations in Europe and America by various transport vectors. In addition, microsatellite alleles in the invasive populations showed a tendency to mutate with the addition or deletion of a single repeat, which is consistent with the stepwise mutation model. Our findings provide a good example of how an aquatic invader with a drastic genetic bottleneck and very low genetic diversity rapidly expands its geographical range.     

Low genetic diversity of the successful invasive African clawed frog Xenopus laevis (Pipidae) in Chile

In Africa, the genus Xenopus presents cryptic species and diverse hybrids between species. It has been assumed that the invasive populations of this genus correspond to X. laevis and that they are derived from the subspecies that inhabits the Mediterranean Cape region of South Africa. In part, this is supported by the successful establishment of this species in several Mediterranean regions of the world. In Mediterranean Chile, Xenopus has invaded an area of about 21,000 km², with scarce attention to genetic aspects underlying its invasion. Using mitochondrial DNA sequences we determined that Xenopus laevis laevis from the Cape region of South Africa is the subspecies that invaded Chile. The analysis indicated that the invaders have low genetic diversity (only two haplotypes, compared to 10 in two localities of their native range), and that probably the invasion in Chile occurred only once. Landscape genetics revealed that factors such as aridity and elevation have determined the spread of the species, both from the ecological and genetic points of view. Our results show that the invasion of the African clawed frog in Chile has been successful for at least 30 years, in spite of low genetic variability, few events of introduction, low propagule pressure, and bottlenecks in the founding population.     

Effects of escape vents on the size selection of whelk (Rapana venosa) and Asian paddle crab (Charybdis japonica) in the small-scale pot fishery of the Yellow Sea,China

Hydrobiologia - The small-scale whelk (Rapana venosa) and Asian paddle crab (Charybdis japonica) pot fishery are of great socio-economic importance to coastal communities of the Yellow Sea, China....     

Genetic relationships between Mt. Halla and Mongolian populations of Hipparchia autonoe (Lepidoptera: Nymphalidae)

Hipparchia autonoe belongs to the family Nymphalidae (Lepidoptera) and is designated as an endangered insect and national monument in Korea. It only inhabits a very restricted area on Mt. Halla but is widely distributed in several Asian countries including Mongolia. A previous study conducted to understand the genetic relationship between Mt. Halla and Mongolian H. autonoe for conservation purposes suffered from a limited number of samples. Therefore, we sequenced the DNA barcode region of an additional 36 H. autonoe individuals, combined them with previous data from 19 individuals, and performed phylogenetic and population genetic analyses. Furthermore, the internal transcribed spacer 2 (ITS2) region was also sequenced from the 36 samples as a nuclear DNA marker. The existence of independent haplotypes, sequence types, and significant F_ST estimates (P < 0.05) between Mt. Halla and Mongolian populations indicated hampered gene flow between the populations. Nevertheless, an absence of a reciprocal monophyletic group in Mt. Halla and Mongolian populations by cytochrome oxidase subunit I gene‐ and ITS2‐based phylogeny suggests that the genetic isolation of the Mt. Halla population from the Mongolian populations seemed not large enough to consider them independent genetic entities.     

Phenotypic variation of life‐history traits in native,invasive, and landrace populations of Brassica tournefortii

Varying environments can result in different patterns of adaptive phenotypes. By performing a common greenhouse experiment, we identified phenotypic differentiation on phenology, leaf morphology, branch architecture, size, and reproduction, among native, invasive, and landrace ranges of Brassica tournefortii. We first compared trait means and fitness functions among ranges, then we analyzed how trait means and selection strength of populations respond to varying aridity. Most traits varied such that landrace > invasive > native. Excluding reproduction, which was positively selected, most trait PCs experienced nonlinear selection in the native range but frequently shifted to directional selection in invasive and/or landrace ranges. The absence of strong clines for trait means in landrace and invasive populations suggest that agricultural practices and novel environments in source locations affected adaptive potential. Selection strength on faster reproductive phenology (negative directional) and leaf margin trait (disruptive) PCs coincided with increasing moisture. In native populations, higher aridity was associated with more days to reproduction, but landrace and invasive populations show stable mean time to reproduction with increasing moisture. A stable adaptive trait can increase range expansion in the invasive range, but stability can be beneficial for future harvest of B. tournefortii seed crops in the face of climate change.     

Genetic relationships between native and introduced populations of the little fire ant Wasmannia auropunctata

Native to much of Central and South America, the little fire ant Wasmannia auropunctata has been rapidly spreading throughout the world. In its introduced range, W. auropunctata is frequently linked with drastic reductions of ant diversity; anecdotal reports of damaging attacks on vertebrates are also common. As it poses an ever-increasing threat to biodiversity, W. auropunctata has emerged as a model system for the study of ecological differences between native and invasive ant populations. These studies have been hampered by a lack of information on the genetic relatedness between native and introduced populations. By investigating the genetic structure of W. auropunctata populations, we provide a framework for conducting phylogenetically independent tests of differences between these ants in their native and invasive ranges. Phylogenetic analyses, based on the cox1 / cox2 region of mtDNA, revealed at least three separate source populations of W. auropunctata distributed across two large clades. Much of the Caribbean region, presumably part of the native range, is inhabited by a clade of ants sharing very similar or identical mtDNA haplotypes, suggesting the possibility of multiple introductions or high levels of gene flow across that area. Most invasive populations in the Pacific were closely related to these ants. The invasive populations in Gabon and New Caledonia arise from another, relatively distantly related clade. Phylogenetically independent contrasts confirm McGlynn's (1999) observation that invasive W. auropunctata populations are smaller than native populations. Given the complex phylogeographical structure of W. auropunctata populations, future comparative work should correct for phylogenetic effects.     

Action and immunoreactivity of neuropeptides in the buccal neuromuscular system of a prosobranch mollusc,Rapana thomasiana

Summary In a prosobranch mollusc, Rapana thomasiana, the catch-relaxing peptide H-Ala-Met-Pro-Met-Leu-Arg-Leu-NH₂ (CARP) was found to depress the contraction of the radula protractor and retractor elicited by electrical stimulations. The action of CARP was in contrast to that of other neuropeptides, H-Phe-Met-Arg-Phe-NH₂ (FMRFamide) and H-Phe-Leu-Arg-Phe-NH₂ (FLRFamide), which enhanced the contraction of the radula protractor and retractor, respectively. By immunohistochemical examinations, FMRFamide-like immunoreactive neurons were found on the rostral side of the right buccal ganglion and the caudal side of the left ganglion, where some CARP-like immunoreactive neurons were also distributed, indicating a possible coexistence of FMRFamide and CARP. FMRFamide- and CARP-like immunoreactivities were also detected in the neuropile of buccal ganglia, radula nerves arising from the ganglia, and nerve fibers in the radula muscles. The present results suggest that FMRFamide- and CARP-like peptides are involved in the regulation of the contraction of the radula muscles.     

Phylogeography of the widespread marine invader Microcosmus squamiger (Ascidiacea) reveals high genetic diversity of introduced populations and non-independent colonizations

The spread of non-indigenous species into new marine habitats represents an increasing threat to global diversity. Genetic techniques provide basic understanding of the invasion processes. The ascidian Microcosmus squamiger is considered to be native to Australia, having been spread worldwide via transoceanic vessels. It has successfully invaded artificial and natural habitats where it has become a pest. We studied phylogeography and genetic structure of 12 M. squamiger populations, including samples from its native range (Australia) and introduced populations from the Indian, Pacific, and Atlantic oceans, as well as the Mediterranean Sea. We amplified 574 bp of the mitochondrial COI gene in 258 individuals and found a total of 52 haplotypes. A haplotype tree revealed two main groups of haplotypes. The relative frequency of each group of haplotypes, multidimensional scaling, and analysis of molecular variance showed important differences between the western Australia localities and the remaining ones (eastern Australia and introduced populations). Furthermore, we found that the colonization of the different areas by M. squamiger has not occurred independently, as many introduced populations shared some low frequency alleles. A nested clade analysis showed a global pattern of restricted gene flow with isolation by distance, although we found episodes of long-distance dispersal in some clades. A contiguous range expansion was detected between Australian populations. We conclude that M. squamiger is native to Australia and has most likely expanded its range of distribution sequentially through worldwide shipping, especially from the harbours of the more populated eastern Australia. In introduced populations, we found a high genetic diversity which suggests enhanced invasive potential. Consequently, there is a need to control this species, as it outcompetes local biota and is an economic threat.