Phylogenetic study of the arginine-vasotocin/arginine-vasopressin-like immunoreactive system in invertebrates

1. A phylogenetic study of arg-vasotocin (AVT)/arg-vasopressin (AVP)-like immunoreactive cells was performed by the PAP method in the central nervous system of invertebrates. 2. The immunoreactivity was detected in the nerve cells of Hydra magnipapillata of the Coelenterata; Neanthes japonica and Pheretima communissima of the Annelida; Pomacea canaliculata, Aplysia kurodai, Oncidium verrucosum, Bradybaena similaris, Achatina fulica, Limax marginatus and Meretrix lamarckii of the Mollusca; Gnorimosphaeroma rayi, Hemigrapsus sanguineus, Gryllus bimaculatus and Baratha brassicae of the Arthropoda; Asterina pectinifera of the Echinodermata; and Halocynthia roretzi of the Protochordata. 3. No immunoreactivity was detected in Bipalium sp. of the Platyhelminthes, or in Procambarus clarkii and Helice tridens of the Arthropoda. 4. From these results, it appears that AVT/AVP is a phylogenetically ancient peptide which is present in a wide variety of invertebrates. 5. The actions of AVT/AVP and its presence in invertebrates are discussed.     

Structure of the small ribosomal subunit RNA of the pulmonate snail, Limicolaria kambeul, and phylogenetic analysis of the Metazoa.

The complete nucleotide sequence of the small ribosomal subunit RNA of the gastropod, Limicolaria kambeul, was determined and used to infer a secondary structure model. In order to clarify the phylogenetic position of the Mollusca among the Metazoa, an evolutionary tree was constructed by neighbor-joining, starting from an alignment of small ribosomal subunit RNA sequences. The Mollusca appear to be a monophyletic group, related to Arthropoda and Chordata in an unresolved trichotomy.     

Phospholipids of sea worms,mollusks, and arthropods

The phospholipid composition of organs and tissues was investigated in representatives of five phyla of marine invertebrates: Annelida (Chaetopterus variopedatus, Serpula vermicularis), Echiuroidea (Urechis unicinctus), Sipunculoidea (Phascolosoma japonicum), Mollusca (Gastropoda: Tectonatica janthostoma, Neptunea polycostata; Bivalvia: Mactra sulcataria, Peronidia venuloza, Patinopecten yessoensis, Crenomytilus grayanus; Cephalopoda: Octopus conispadiceus, Todarodes pacificus), and Arthropoda (Paralythodes camtschatica, Erimacrus isenbekii, Hemigrapsus sanguineus, Pinixa rathbunii). The specificity of phospholipid distribution was shown to be related to the taxonomic position of marine invertebrates and functional properties of their organs and tissues. In Echiuroidea, Sipunculoidea, and Arthropoda, ceramide aminoethylphosphonate was found only in the digestive organs. This suggests an exogenous origin of this phospholipid.     

Distribution of opine dehydrogenases and lactate dehydrogenase activities in marine animals

• 1.1. Opine dehydrogenases (OpDHs) and lactate dehydrogenase (LDH) activities were determined in various marine animals. OpDHs were detected in six marine invertebrate phyla; Porifera, Coelenterata, Annelida, Mollusca, Arthropoda and Echinodermata in phylogenic sequence.
• 2.2. Among several OpDHs, tauropine dehydrogenase (TaDH) occurred widely in marine invertebrates, from Porifera to Echinodermata.
• 3.3. With a few exceptions, total OpDHs activities exceeded that of LDH activity in the marine invertebrates investigated.
• 4.4. With respect to anaerobic glycolysis, OpDHs are indicated to play an important role in phylogenically lower invertebrates, whereas LDH is more important in higher animals.

     

Phylogenetic position of Sipuncula derived from multi‐gene and phylogenomic data and its implication for the evolution of segmentation

The phylogenetic position of Sipuncula, a group of unsegmented marine worms, has been controversial for several decades: Especially based on morphological data, closer relationships to Mollusca or Annelida were among the most favoured hypotheses. Increasing amounts of molecular data in recent years have consistently placed Sipuncula either in close affinity to or even within Annelida, the segmented worms, and rejected a close relationship to Mollusca. Yet, it remained uncertain whether Sipuncula is the sister group of Annelida or an annelid subtaxon. Therefore, herein we gathered data for five nuclear genes, which have been rarely used regarding Annelida and Sipuncula, and combined these with data for six previously used genes to further elucidate the phylogenetic position of Sipuncula. We also compiled a data set for 78 ribosomal proteins from publicly available genomic data sets. These are the two largest data sets for annelids with more than 10 taxa to date. All analyses placed Sipuncula within Annelida. For the first time, topology tests significantly rejected the possibility that Sipuncula is sister to Annelida. Thus, our analyses revealed that Sipuncula had secondarily lost segmentation. Given that unsegmented Echiura is also an annelid subtaxon, segmentation, a key character of Annelida, is much more variable than previously thought. Yet, this conclusion does not support the hypothesis that the last common ancestor of Annelida, Arthropoda and Chordata was segmented, assuming several losses along the branches leading to them. As yet no traces of segmentation could be shown in taxa exhibiting serially organized organ systems such as certain Mollusca, while in Sipuncula and Echiura such traces could be demonstrated. An independent origin of segmentation in Annelida, Arthropoda and Chordata thus appears to be more plausible and parsimonious.     

川西峨眉晚白垩世夹关期河流沉积中的痕迹化石群落*

晚白垩世夹关组中的痕迹化石群落至少由12个痕迹属17个痕迹种组成,其中包括5个新痕迹种,即Cystichrtium cuwatitivum,Steinichnus laryus,Paradidymaulichnus emeiertsis,Monmorphichnus lineates和Rusophycus univalvis.这一化石群落主要是无脊椎动物的进食迹、觅食迹、爬迹、停息迹和居住迹,其中多数呈下浮痕和全浮痕保存,并形成于经常干旱的河流环境(大多出现在泛滥平原沉积中).该群落可识别出两个痕迹化石组合,即1) Scoyenia-Steinichnus-Rusophycus组合,它主要产自泛滥平原和漫滩环境;2)Skolithos-Arenicolites组合,它代表一种水道砂坝或曲流砂坝环境.     

软体动物和甲壳动物酚氧化酶的研究进展

软体动物和甲壳动物的很多品种都是重要的经济养殖品种.随着养殖业集约化程度的提高,各种病害频繁发生,造成了巨大的经济损失.于是越来越多的人开始关注软体动物和甲壳动物的免疫防御系统,并对其进行研究.酚氧化酶(phenoloxidase,PO)是一种含铜的氧化酶,广泛存在于微生物、动物和植物体内.作为酚氧化酶原激活系统的重要一员,PO在无脊椎动物的先天免疫机制中起着重要的作用,有关其生物化学、免疫学和分子生物学特性的研究一直以来受到广泛关注,尤其在节肢动物中进展很快.作者对酚氧化酶在软体和甲壳动物中的功能、组织定位及表达、基因克隆和序列分析及其系统演化等几个方面的研究进展进行了综述.基因序列分析和系统进化树证据均表明,催化功能相同的软体动物酪氨酸酶与节肢动物PO的基因有较大差异.该结果对目前被广泛接受并使用的酪氨酸酶专门用于哺乳类,酚氧化酶专门用于无脊椎动物的分类法提出了挑战.因此作者建议,将酚氧化酶专门用于节肢动物,酪氨酸酶用于软体动物等非节肢动物和脊椎动物.     

Phylogenetic position of Nemertea derived from phylogenomic data

Nemertea and Platyhelminthes have traditionally been grouped together because they possess a so-called acoelomate organization, but lateral vessels and rhynchocoel of nemerteans have been regarded as coelomic cavities. Additionally, both taxa show spiral cleavage patterns prompting the placement of Nemertea as sister to coelomate Protostomia, that is, either to Neotrochozoa (Mollusca and Annelida) or to Teloblastica (Neotrochozoa plus Arthropoda). Some workers maintain a sister group relationship of Nemertea and Platyhelminthes as Parenchymia because of an assumed homology of G?tte's and Müller's larvae of polyclad Platyhelminthes and the pilidium larvae of heteronemerteans. So far, molecular data were only able to significantly reject a sister group relationship to Teloblastica. Although phylogenomic data are available for Platyhelminthes, Annelida, Mollusca, and Arthropoda, they are lacking for Nemertea. Herein, we present the first analysis specifically addressing nemertean phylogenetic position using phylogenomic data. More specifically, we collected expressed sequence tag data from Lineus viridis (O.F. Müller, 1774) and combined it with available data to produce a data set of 9,377 amino acid positions from 60 ribosomal proteins. Maximum likelihood analyses and Bayesian inferences place Nemertea in a clade together with Annelida and Mollusca. Furthermore, hypothesis testing significantly rejected a sister group relationship to either Platyhelminthes or Teloblastica. The Coelomata hypothesis, which groups coelomate taxa together to the exclusion of acoelomate and pseudocoelomate taxa, is not congruent with our results. Thus, the supposed acoelomate organization evolved independently in Nemertea and Platyhelminthes. In Nemertea, evolution of acoely is most likely due to a secondary reduction of the coelom as it is found in certain species of Mollusca and Annelida. Though looking very similar, the G?tte's and Müller's larvae of polyclad Platyhelminthes are not homologous to the pilidium larvae of heteronemerteans. Finally, the convergent evolution of segmentation in Annelida and Arthropoda is further substantiated.     

Distribution of sulfated mucopolysaccharides in invertebrates.

The sulfated mucopolysaccharide composition of 22 species of invertebrates belonging to the phyla Arthropoda, Mollusca, Annelida, Tunicata, Echinodermata, Coelenterata, and Porifera was analyzed. It is shown that all the species contain variable amounts of one or more types of sulfated mocopolysaccharides, most of which similar to the ones found in vertebrates. It is shown also that each species has a characteristic composition, differing from each other regarding the relative amount and type of chondroitin sulfates A, B, and C, heparitin sulfate, and heparin. The possible biological role of the sulfated mucopolysaccharides in cell recognition or aggregation or both is discussed in view of the present findings.     

Phylogeny of protostome worms derived from 18S rRNA sequences

The phylogenetic relationships of protostome worms were studied by comparing new complete 18S rRNA sequences of Vestimentifera, Pogonophora, Sipuncula, Echiura, Nemertea, and Annelida with existing 18S rRNA sequences of Mollusca, Arthropoda, Chordata, and Platyhelminthes. Phylogenetic trees were inferred via neighbor-joining and maximum parsimony analyses. These suggest that (1) Sipuncula and Echiura are not sister groups; (2) Nemertea are protostomes; (3) Vestimentifera and Pogonophora are protostomes that have a common ancestor with Echiura; and (4) Vestimentifera and Pogonophora are a monophyletic clade.      

Metagenomic analysis of the marine coastal invertebrates of South Korea as assessed by Ilumina MiSeq

Metagenomic analysis was carried out for the first time on the marine coastal invertebrates of South Korea. Samples collected from coastal areas of Korea were filtered through a 63 µm mesh, then their 18S rDNA V4 regions were amplified. High-throughput sequencing of PCR amplicons using Illumina MiSeq and BLAST against the SILVA database showed that a total of 319 eukaryotic Operational Taxonomic Units were identified at the species level. Annelida, Arthropoda, Mollusca, Nematoda, and Platyhelminthes and for 92.23% of the total 103 metazoan species belonging to 101 genera, 75 families, and 10 phyla. Of these, several taxa previously unreported to exist in Korea were detected at the family level compared with the integrated database from three main Korean biodiversity DBs (MABIK, KOMBIS, and MRBR). Analysis of beta diversity of the community structure of invertebrates indicated that the composition of marine invertebrates is likely to be affected by habitat type rather than geographical distance. The present study showed that metagenomic high-throughput technology can be used to unravel species diversity and for various studies regarding marine invertebrate community structure.     

Occurrence,abundance and distribution of benthic macroinvertebrates in the Nyando River catchment,Kenya

A baseline study was conducted of the occurrence of macroinvertebrates at 26 sites in the Nyando River catchment in 2005–2006. A total of 13 orders and 16 families of Arthropoda, Mollusca, Platyhelminthes and Annelida were collected, with the order Ephemeroptera being most abundant in the up- and mid-stream reaches, followed by Hemiptera and Plecoptera respectively. The downstream sections of the river were dominated by Hirudinea and tubificids, as the water quality deteriorated mainly due to local land use, raw sewage effluent discharge and annual floods. Insects and annelids were the main invertebrates found and the extent of pollution increased from mid-section (Site 15) downwards as the river flowed into the Winam Gulf. Stringent management measures are required to safeguard the environment and ecosystems of Lake Victoria.     

Gut-islet endocrinology-some evolutionary aspects

Immunological and biological studies have shown that many of the mammalian gastroenteropancreatic (GEP) hormones have counterparts in lower vertebrates. Hormonal localization in cyclostomes and fishes suggests that insulin was phylogenetically the first islet hormone, followed by somatostatin, glucagon and, last, pancreatic polypeptide (PP). Some of the GEP peptides are present in the central and peripheral nervous system of lower vertebrates as well as mammals. GEP hormone-like substances resembling insulin, somatostatin, glucagon, PP, gastrin, secretin, VIP, substance P and enkephalin also occur in protostomian invertebrates (Annelida, Arthropoda, Mollusca), particularly in their nervous system. These findings indicate that the vertebrate hormones may have originated in neural tissue before the development of the vertebrate line of evolution.     

Identification of Several Cytoplasmic HSP70 Genes from the Mediterranean Mussel (Mytilus galloprovincialis) and Their Long-Term Evolution in Mollusca and Metazoa

The HSP70 protein family consists one of the most conserved and important systems for cellular homeostasis under both stress and physiological conditions. The genes of this family are poorly studied in Mollusca, which is the second largest metazoan phylum. To study these genes in Mollusca, we have isolated and identified five HSP70 genes from Mytilus galloprovincialis (Mediterranean mussel) and investigated their short-term evolution within Mollusca and their long-term evolution within Metazoa. Both sequence and phylogenetic analyses suggested that the isolated genes belong to the cytoplasmic (CYT) group of the HSP70 genes. Two of these genes probably represent cognates, whereas the remaining probably represent heat-inducible genes. Phylogenetic analysis including several molluscan CYT HSP70s reveals that the cognate genes in two species have very similar sequences and form intraspecies phylogenetic clades, differently from most metazoan cognate genes studied thus far, implying either recent gene duplications or concerted evolution. The M. galloprovincialis heat-inducible genes show intraspecies phylogenetic clustering, which in combination with the higher amino acid than nucleotide identity suggests that both gene conversion and purifying selection should be responsible for their sequence homogenization. Phylogenetic analysis including several metazoan HSP70s suggests that at least two types of CYT genes were present in the common ancestor of vertebrates and invertebrates, the first giving birth to the heat-inducible genes of invertebrates, whereas the other to both the heat-inducible genes of vertebrates and the cognate genes of all metazoans. These analyses also suggest that inducible and cognate genes seem to undergo divergent evolution. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users. [Reviewing Editor: Dr. Yves Van de Peer] Elena Drosopoulou and Nikolas Nikolaidis contributed equally to the present report.     

Marine invertebrate cytochrome P450: emerging insights from vertebrate and insects analogies

Cytochrome P450 enzymes (P450s) are responsible for the oxidative metabolism of a plethora of endogenous and exogenous substrates. P450s and associated activities have been demonstrated in numerous marine invertebrates belonging to the phyla Cnidaria, Annelida (Polychaeta), Mollusca, Arthropoda (Crustacea) and Echinodermata. P450s of marine invertebrates and vertebrates show considerable sequence divergence and the few orthologs reveal the selective constraint on physiologically significant enzymes. P450s are present in virtually all tissues of marine invertebrates, although high levels usually are found in hepatic-like organs and steroidogenic tissues. High-throughput technologies result in the rapid acquisition of new marine invertebrate P450 sequences; however, the understanding of their function is poor. Based on analogy to vertebrates and insects, it is likely that P450s play a pivotal role in the physiology of marine invertebrates by catalyzing the biosynthesis of signal molecules including steroids such as 20-hydroxyecdysone (the molting hormone of crustaceans). The metabolism of many exogenous compounds including benzo(a)pyrene (BaP), pyrene, ethoxyresorufin, ethoxycoumarin and aniline is mediated by P450 enzymes in tissues of marine invertebrates. P450 gene expression, protein levels and P450 mediated metabolism of xenobiotics are induced by PAHs in some marine invertebrate species. Thus, regulation of P450 enzyme activity may play a central role in the adaptation of animals to environmental pollutants. Emphasis should be put on the elucidation of the function and regulation of the ever-increasing number of marine invertebrate P450s.     

Natural products from marine invertebrates against <Emphasis Type="Italic">Leishmania</Emphasis> parasites: a comprehensive review

Parasitic infections by Leishmania parasites remains a severe public health problem, especially in developing countries where it is highly endemic. Chemotherapy still remains a first option for the treatment of those diseases, despite the fact that available drugs exhibit a variety of shortcomings. Thus, innovative, less toxic more affordable and effective antileishmanial agents are urgently needed. The marine environment holds an immeasurable bio- and chemical diversity, being a valuable source of natural products with therapeutic potential. As invertebrates comprise about 60 % of all marine organisms, bioprospecting this class of organisms for antileishmanial properties may unravel unique and selective hit molecules. In this context, this review covers results on the literature of marine invertebrate extracts and pure compounds evaluated against Leishmania parasites mainly by in vitro methods. It comprises results obtained from the phyla Porifera, Cnidaria, Bryozoa (Ectoprota), Mollusca, Echinodermata, Annelida, Cetnophora, Platyhelminthes, sub phyla Crustacea (phylum Arthropoda) and Tunicata (phylum Chordata). Moreover, structure–activity relationships and possible mechanisms of action are mentioned, whenever available information is provided. About 70 species of marine invertebrates belonging to seven different phyla are included in this work. Besides a variety of crude extracts, a total of 140 pure compounds was tested against different Leishmania species. Although the research on the antileishmanial potential of marine invertebrates is in its early beginnings, promising results have been achieved that encourage further research. As more extracts and compounds are being screened, the possibility of finding active and selective antileishmanial molecules increases, rising new hope in the search for new treatments against leishmaniases.     

On the status of the study of invertebrate neurons in tissue culture--phyla Mollusca and Annelida

The utilization of tissue culture in neurobiological studies is discussed for all phyla phylogenetically preceding Phylum Arthropoda. Only two phyla, Mollusca and Annelida, are represented in such studies. The members of Phylum Mollusca which have been so investigated are Aplysia, Helisoma and Lymnaea. The mollusc Aplysia has been used to investigate several processes, including neurosecretion, synaptic transmission and synaptogenesis. Helisoma was employed to study factors regulating neurite growth and the specificity of synapse formation; mechanisms of neurite growth were investigated in the snail Lymnaea. The only member of Phylum Annelida involved in appropriate studies has been the leech Hirudo. This organism was used to investigate axonal regeneration and synaptic mechanisms.     

Differential localization of vasopressin- and oxytocin-immunoreactive cells and conventional neurosecretory cells in the ganglia of the earthworm Pheretima hilgendorfi

Cells containing arginine vasopressin (AVP)- and oxytocin (OXT)-like substances were immunohistochemically visualized in the cerebral, subesophageal, and ventral nerve cord ganglia of the earthworm Pheretima hilgendorfi. Whether these anti-AVP– and anti-OXT–reactive cells are identical with classical aldehyde fuchsin (AF)-positive neurosecretory cells was tested in serial sections. In all ganglia, groups of scattered neuronal cell bodies and axons strongly reactive to AVP and OXT antisera were observed, but AF-positive cells consisting of type a (dark blue) and type b (purple) cells were predominantly present in the cerebral and subesophageal ganglia. In the cerebral and subesophageal ganglia anti-AVP– and anti-OXT–reactive cells were generally larger than AF-positive cells. Some AF-positive cells were reactive either to anti-AVP or anti-OXT serum, but some failed to react to either serum. Anti-AVP– and anti-OXT–reactive cells were not immunoreactive to OXT and AVP antisera, respectively. Electron microscopic observations showed that the granules of type a cells were larger and less electron dense than those of type b cells and anti-AVP–reactive cells. The present cytological observations clearly showed that AVP- and OXT-like substances were widely present in the ganglionic cells of the earthworm     

An evolutionary tree for invertebrate globin sequences

Summary A phylogenetic tree was constructed from 245 globin amino acid sequences. Of the six plant globins, five represented the Leguminosae and one the Ulmaceae. Among the invertebrate sequences, 7 represented the phylum Annelida, 13 represented Insecta and Crustacea of the phylum Arthropoda, and 6 represented the phylum Mollusca. Of the vertebrate globins, 4 represented the Agnatha and 209 represented the Gnathostomata. A common alignment was achieved for the 245 sequences using the parsimony principle, and a matrix of minimum mutational distances was constructed. The most parsimonious phylogenetic tree, i.e., the one having the lowest number of nucleotide substitutions that cause amino acid replacements, was obtained employing clustering and branch-swapping algorithms. Based on the available fossil record, the earliest split in the ancestral metazoan lineage was placed at 680 million years before present (Myr BP), the origin of vertebrates was placed at 510 Myr BP, and the separation of the Chondrichthyes and the Osteichthyes was placed at 425 Myr BP. Local molecular clock calculations were used to date the branch points on the descending branches of the various lineages within the plant and invertebrate portions of the tree. The tree divided the 245 sequences into five distinct clades that corresponded exactly to the five groups plants, annelids, arthropods, molluscs, and vertebrates. Furthermore, the maximum parsimony tree, in contrast to the unweighted pair group and distance Wagner trees, was consistent with the available fossil record and supported the hypotheses that the primitive hemoglobin of metazoans was monomeric and that the multisubunit extracellular hemoglobins found among the Annelida and the Arthropoda represent independently derived states.     

A clarification of the two types of invertebrate pleated septate junction

It is confirmed that there are two distinct variations of invertebrate septate junction. The first of these, the ‘lower invertebrate pleated septate junction’, is described fully using conventional thin section, lanthanum tracer and freeze-fracture techniques. The second type, the well-known pleated septate junction characteristic of the molluscs and athropods, is renamed the ‘mollusc-arthropod pleated septate junction’, and is described briefly to allow easier comparison between the two variations. As both types have now been studied in a range of invertebrate phyla the results can be used as a basis for discussing their respective phylogenetic positions. The lower invertebrate pleated septate junction occurs in several groups in the minor phyla immediately above the Coelenterata and in the lower phyla of both the deuterostome and proterostome lineages. The mollusc-arthropod pleated septate junction is restricted to the Mollusca and Arthropoda as its name implies.