Distinct genotype and antigenicity among genogroup II sapoviruses

SaV, a pathogen of acute gastroenteritis, is divided into five genogroups, GI to GV. However, the relation between SaV antigenicity and genetic clusters is not fully understood. We have recently identified two GII SaV strains, Mc10 and C12, which are grouped into the same cluster based on the polymerase but are grouped into distinct clusters based on the capsid. To evaluate the difference in antigenicity between these two strains, VLP were expressed in mammalian cells. An antigen ELISA demonstrated for the first time that strains in the same GII SaV genogroup, but within different clusters, have distinct antigenicities.     

聚合牛血红蛋白抗原性的初步研究

对乙醇醛聚合的牛血红蛋白的抗原性进行了研究。将聚合的牛血红蛋白桉兔血量的10％和20％分别输入兔耳缘静脉,间隔7天后重复输液,共输注3次。ELISA检测未显示抗体产生。将聚合的牛血红蛋白、人血红蛋白和兔血红蛋白分别与免疫佐剂混合常规免疫家兔3次,并用上述抗原包被聚乙烯板,用ELISA方法检测抗体滴度,结果显示聚合牛血红蛋白和人血红蛋白加佐剂免疫家兔后均产生抗体,且有交叉反应,表明这两种血红蛋白有同源性,存在相似的抗厚决定簇。兔血红蛋白免疫家兔后无抗体产生,且无交叉反应,表明机体对自体蛋白有天然的耐受。     

Conformational heterogeneity in polypeptide cardiac stimulants from sea anemones

High-resolution 1H NMR spectra at 300 MHz of the polypeptide cardiac stimulants anthopleurin-A and Anemonia sulcata toxin II reveal conformational heterogeneity in both molecules. The two conformations, manifest in a number of split 1H resonances, are in slow exchange over a wide range of pH and temperature. Heterogeneity affects a region of these molecules containing the structurally and functionally important Asp residues. By comparison with a homologous polypeptide Anemonia sulcata toxin I, which does not show this type of heterogeneity, it is suggested that the heterogeneity may originate in cis-trans isomerism of the Gly-40 to Pro-41 peptide bond.     

The structural characterization and antigenicity of the S protein of SARS-CoV

The corona-like spikes or peplomers on the surface of the virion under electronic microscope are the most striking features of coronaviruses. The S (spike) protein is the largest structural protein, with 1,255 amino acids, in the viral genome. Its structure can be divided into three regions: a long N-terminal region in the exterior, a characteristic transmembrane (TM) region, and a short C-terminus in the interior of a virion. We detected fifteen substitutions of nucleotides by comparisons with the seventeen published SARS-CoV genome sequences, eight (53.3%) of which are non-synonymous mutations leading to amino acid alternations with predicted physiochemical changes. The possible antigenic determinants of the S protein are predicted, and the result is confirmed by ELISA (enzyme-linked immunosorbent assay) with synthesized peptides. Another profound finding is that three disulfide bonds are defined at the C-terminus with the N-terminus of the E (envelope) protein, based on the typical sequence and posit     

Neural pathways and innervation of cnidocytes in tentacles of sea anemones

Our previously published studies are here reviewed detailing neuro-cnidocyte synapses, demonstrating putative neurotransmitter substances, and identifying complex neural pathways in sea anemones. Synapses were traced to their contacts on nematocytes and spirocytes by transmission electron microscopy of serial thin sections of tentacles. In five animals, cells containing microbasic p-mastigophores had synapses with clear vesicles, whereas cells containing basitrichous isorhizas had synapses with dense-cored vesicles, providing preliminary evidence for a selectivity of neurotransmitter types for different nematocysts. Either clear or dense-cored synaptic vesicles were also present at neuro-spirocyte contacts. Antho-RFamide immunoreactivity occurred in some anthozoan synaptic vesicles and immunogold labeling of serotonin was found at a neuro-spirocyte synapse. Neural pathways included direct innervation of spirocytes by sensory cells, sequential neuro-neuro-spirocyte and neuro-neuro-nematocyte synapses and reciprocal synapses involving axons of both sensory cells and ganglion cells. Such synaptic patterns resemble neuro-effector pathways found in higher animals and lay to rest the independent effector hypothesis for cnidocyte discharge in tentacles of sea anemones.     

Enzymatic N-glycan analysis of 31 kDa molecule in plerocercoid of Spirometra mansoni (sparganum) and its antigenicity after chemical oxidation

A highly specific antigenic protein of 31 kDa from plerocercoid of Spirometra mansoni (sparganum) was obtained by gelatin affinity and Mono Q anion-exchange column chromatography. The purified 31 kDa protein was subjected to N-glycan enzymatic digestion for structural analysis. The relative electrophoretic mobility was analyzed by SDS-PAGE, before and after digestion. On SDS-PAGE after enzymatic digestion, the 31 kDa protein showed a molecular shift of approximately 2 kDa, which indicated the possession of complex N-linked oligosaccharides (N-glycosidase F sensitive) but not of high-mannose oligosaccharides (endo-beta-N-acetylglucosaminidase H, non-sensitive). Chemically periodated 31 kDa protein showed statistically non-significant changes with human sparganosis sera by enzyme linked immunosorbent assay (ELISA). Therefore, the dominant epitopes of the 31 kDa molecule in human sparganosis were found to be mainly polypeptide, while N-glycans of the antigenic molecule in sparganum was minimal in anti-carbohydrate antibody production.     

Convenient nomenclature of cysteine-rich polypeptide toxins from sea anemones

Polypeptide toxins are the main constituents of natural venoms. Considerable progress in the study of these molecules has resulted in the determination of a large number of structurally related sequences. To classify newly discovered molecules, a rational nomenclature for naming peptide toxins was developed, which takes into account toxin biological activity, the species name, and structural peculiarities of the polypeptide. Herein, we suggest modifications to this nomenclature for cysteine-rich polypeptide toxins from sea anemones and describe 11 novel polypeptide structures deduced after common database revision.     

Polypeptide cytolytic toxins from sea anemones (Actiniaria)

Abstract Biochemical and biological properties of 30 cytolytic polypeptide toxins isolated from 18 species of sea anemones ( Actiniaria ) are presented and classified into three groups according to their molecular mass, isoelectric points and the molecular mechanism of action. Phospholipase A₂-like toxins (30 kDa) from Aiptasia pallida are dissimilar to acidic metridiolysin (80 kDa) from Metridium senile and the group of about 27 predominantly basic toxins, having a molecular mass of 16–20 or 10 kDa, inhibited by sphingomyelin. They are lethal for both invertebrates and vertebrates, cardiotoxic, cutolytic and cytotoxic. Pharmacological activities, cytotoxic and cytolytic properties are mediated, at least in part, by forming pores in lipid membranes. Channels, 1–2 nm in diameter, formed in planar lipid membranes are cation selective and rectified. The mechanisms and some characteristics of ion channel formation by the toxins in the cells as well as in artificial lipid membranes are summarized and discussed in view of the structure-function studies of the toxins. Putative biological roles of toxins, based on their channel-forming activity, in the capture and killing of prey, digestion, repelling of predators and intraspecific spatial competition are suggested.     

Cadherin 23-like polypeptide in hair bundle mechanoreceptors of sea anemones

We investigated hair bundle mechanoreceptors in sea anemones for a homolog of cadherin 23. A candidate sequence was identified from the database for Nematostella vectensis that has a shared lineage with vertebrate cadherin 23s. This cadherin 23-like protein comprises 6,074 residues. It is an integral protein that features three transmembrane alpha-helices and a large extracellular loop with 44 contiguous, cadherin (CAD) domains. In the second half of the polypeptide, the CAD domains occur in a quadruple repeat pattern. Members of the same repeat group (i.e., CAD 18, 22, 26, and so on) share nearly identical amino acid sequences. An affinity-purified antibody was generated to a peptide from the C-terminus of the cadherin 23-like polypeptide. The peptide is expected to lie on the exoplasmic side of the plasma membrane. In LM, the immunolabel produced punctate fluorescence in hair bundles. In TEM, immunogold particles were observed medially and distally on stereocilia of hair bundles. Dilute solutions of the antibody disrupted vibration sensitivity in anemones. We conclude that the cadherin 23-like polypeptide likely contributes to the mechanotransduction apparatus of hair bundle mechanoreceptors of anemones.     

Fission in sea anemones: integrative studies of life cycle evolution

Sea anemones (Phylum Cnidaria; Class Anthozoa, Order Actiniaria)exhibit a diversity of developmental patterns that include cloningby fission. Because natural histories of clonal and aclonalsea anemones are quite different, the gain and loss of fissionis an important feature of actiniarian lineages. We have usedmitochondrial DNA and nuclear intron DNA phylogenies to investigatethe evolution of longitudinal fission in sixteen species inthe genus Anthopleura, and reconstructed an aclonal ancestorthat has given rise at least four times to clonal descendents.For A. elegantissima from the northeastern Pacific Ocean, atransition to clonality by fission was associated with an up-shorehabitat shift, supporting prior hypotheses that clonal growthis an adaptation to the upper shore. Fission in Actiniaria likelyprecedes its advent in Anthopleura, and its repeated loss andgain is perplexing. Field studies of the acontiate sea anemoneAiptasia californica provided insight to the mechanisms thatregulate fission: subtidal Aiptasia responded to experimentallydestabilized substrata by increasing rates of pedal laceration.We put forth a general hypothesis for actiniarian fission inwhich sustained tissue stretch (a consequence of substratuminstability or intrinsic behavior) induces tissue degradation,which in turn induces regeneration. The gain and loss of fissionin Anthopleura lineages may only require the gain and loss ofsome form of stretching behavior. In this view, tissue stretchinitiates a cascade of developmental events without requiringcomplex gene regulatory linkages.     

Longitudinal study of aspergillosis in sea fan corals

Aspergillosis (a fungal disease) is affecting sea fan corals Gorgonia spp. throughout the Caribbean. To measure the impact of this disease, we established longitudinal, or in other words individual-based, monitoring studies on 3 reefs in the Florida Keys, USA, to obtain estimates of incidence, rates of disease progress, recovery, and mortality. At Western Dry Rocks (near Key West), 40 Gorgonia ventalina colonies (20 initially healthy and 20 initially diseased) were photo-monitored between June 1996 and May 1998. Additional sea fans were visually monitored during 2 localized outbreaks at Conch (May 1998 to September 1999) and Carysfort (July 2000 to May 2001) reefs located in the Upper Keys. Data from Western Dry Rocks showed that over a 2 yr period, the incidence rate was 0.58 sea fans yr(-1) and that tissue purpling can lead to tissue loss and subsequently to mortality, albeit at low frequencies. Most sea fans, once infected, maintained a low level of damage over time. Only 3 fans recovered from the disease; however 2 were subsequently re-infected. Case fatality rate was 10% (2 of 20 initially infected died), which is equivalent to 5% yr(-1). However, mortality can increase during localized outbreaks. At Conch, mortality was 46% yr(-1) among infected sea fans (compared to 8% yr(-1) at Carysfort, a less impacted site, during the same period). During an outbreak at Carysfort, mortality was 95% yr(-1) among diseased sea fans. These data clearly demonstrate the significant role aspergillosis plays in the population ecology of sea fan corals.     

The relationship of structure of glucoamylase and glucose oxidase to antigenicity

Glucoamylase and glucose oxidase fromAspergillus niger have been purified to homogeneity by chromatography on DEAE-cellulose and the purified enzymes have been used to investigate structural and antigenicity relationships. In structure, glucoamylase and glucose oxidase are glycoproteins containing 14% and 16% carbohydrate. Earlier methylation and reductive -elimination results have shown that glucoamylase has an unusual arrangement of carbohydrate residues, with 20 single mannose units and 25 di-, tri-, or tetrasaccharide chains of mannose, glucose, and galactose, all attached O-glycosidically to serine and threonine residues of the protein moiety. The antigenicity of the glucoamylase has now been found to reside predominantly in the types and arrangement of the carbohydrate chains. Glucose oxidase contains mannose, galactose, and glucosamine in the N-acetyl form in the native enzyme, but the complete structure of the carbohydrate chains has not yet been determined. The antigenicity of this enzyme does not reside in the carbohydrate units, but rather in the polypeptide chains of the two subunits of the enzyme. Glucose oxidase can be dissociated into subunits by mercaptoethanol and sodium dodecyl sulfate treatment, while glucoamylase cannot be dissociated, but undergoes only an unfolding of the polypeptide chain under these conditions. The subunits of glucose oxidase do not react with the anti-glucose oxidase antibodies, but the unfolded molecule and peptide fragments produced from glucoamylase by cyanogen bromide cleavage do react with antiglucoamylase antibodies.     

Modes of reproduction in sea anemones (Cnidaria,Anthozoa)

The data on different modes of reproduction in sea anemones are generalized. These animals can reproduce sexually in an ordinary way or by parthenogenesis. Asexual reproduction occurs in various forms, such as transverse and longitudinal fission, pedal laceration, or autotomy of tentacles. Specific features of different variants of sexual and asexual reproduction and their combinations in sea anemones from different habitats of the World Ocean are discussed.     

Ultrastructure of the tentacle nerve plexus and putative neural pathways in sea anemones

Abstract. Neurons of sea anemone tentacles receive stimuli via sensory cells and process and transmit information via a plexus of nerve fibers. The nerve plexus is best revealed by scanning electron microscopy of epidermal peels of the tentacles. The nerve plexus lies above the epidermal muscular layer where it appears as numerous parallel longitudinal and short interconnected nerve fibers in Calliactis parasitica . Bipolar and multipolar neurons are present and neurites form interneuronal and neuromuscular synaptic contacts. Transmission electron microscopy of cross sections of tentacles of small animals, both C. parasitica and Aiptasia pallida , reveals bundles of 50–100 nerve fibers lying above groups of longitudinal muscle fibers separated by intrusions of mesoglea. Smaller groups of 10–50 slender nerve fibers are oriented at right angles to the circular muscle formed by the bases of the digestive cells. The unmyelinated nerve fibers lack any glial wrapping, although some bundles of epidermal fibers are partially enveloped by cytoplasmic extensions of the muscle cells; small gastrodermal nerve bundles lie between digestive epithelial cells above their basal myonemes. A hypothetical model for sensory input and motor output in the epidermal and gastrodermal nerve plexuses of sea anemones is proposed.