Larval dispersal,recruitment, and adult distribution of the brooding stony octocoral<Emphasis Type="Italic"> Heliopora coerulea</Emphasis> on Ishigaki Island,southwest Japan

Larval dispersal and recruitment are important factors that determine the distribution of adult corals. The relationships between larval dispersal, recruitment, and the adult distribution of the blue octocoral, Heliopora coerulea, were investigated on Shiraho Reef, Ishigaki Island, southwest Japan. Heliopora coerulea is a surface brooder that releases planulae in June or July on Shiraho Reef. We observed planulae between 1998 and 2000 and found that they did not swim actively; instead, they crawled into their settlement positions after becoming grounded on the substratum. Planulae occurred throughout the water column and were dispersed by tidal and wind-driven currents around the parent population on the reef flat. Recruitment was observed only within 350 m of the parent populations, including areas between the branches of the adult colony. The planulae of H. coerulea had a narrow dispersal range as a result of their mostly benthic, shorter larval duration, and the influence of weaker currents. Thus, the dispersal distance of larvae is determined by their position in the water column, the currents that deliver the larvae, and the competency period of the larvae. The narrow dispersal range of H. coerulea was consistent with recruitment of sexually derived larvae onto their natal reef.     

Feeding capability of black scraper <Emphasis Type="Italic">Thamnaconus modestus</Emphasis> on giant jellyfish <Emphasis Type="Italic">Nemopilema nomurai</Emphasis> evaluated through field observations and tank experiments

Although many fish species are known to feed on jellyfish, only a few quantitative studies on this subject have been conducted in the field or laboratory. We combined field observations and feeding experiments to quantitatively evaluate the potential feeding capability of the black scraper Thamnaconus modestus on giant jellyfish Nemopilema nomurai in a jellyfish-abundant area. Underwater observations revealed that shoals of T. modestus fed voraciously on jellyfish when the jellyfish were close to the fish’s seaweed habitat. Gut contents of field-collected T. modestus almost exclusively consisted of jellyfish. In tank trials, feeding activity of black scraper was high when light intensity was between about 1.1 lx and 50 × 10³ lx. The estimated feeding speed of T. modestus on the jellyfish in the Sea of Japan when the jellyfish bloom occurred was 10.0 ± 2.0 times fish body weight per day. The results support the prediction that T. modestus and probably other coastal medusivorous fishes have a substantial capability to eliminate jellyfish blooms. Considering that they are highly dependent on seaweed bed, protection of such habitats for these medusivores may be the most cost-efficient control method for jellyfish blooms.     

Modelling the potential geographic distribution of <Emphasis Type="Italic">Trissolcus japonicus</Emphasis>: a biological control agent of the brown marmorated stink bug, <Emphasis Type="Italic">Halyomorpha halys</Emphasis>

Trissolcus japonicus Ashmead (Hymenoptera: Scelionidae) is an endoparasitoid of the eggs of the brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), a major agricultural pest native to China, Japan, South Korea and Taiwan. We used CLIMEX to estimate the potential global distribution of T. japonicus with particular reference to New Zealand. In its native range the model predicts the presence, or a potential expansion, of T. japonicus into most of humid-subtropical and humid-continental areas. Globally, the model projects that many temperate, Mediterranean and subtropical areas could suit the establishment of T. japonicus. In New Zealand, the north appears moderately to highly suitable for T. japonicus, while southern regions are mostly marginal. The risk posed by T. japonicus to non-target species in New Zealand is predicted to vary between different non-targets. CLIMEX projections of the potential distribution of T. japonicus provide guidance for release sites of this parasitoid if approved for importation and release in New Zealand.     

Histological and cytological studies of plant infection by <Emphasis Type="Italic">Erysiphe euonymi</Emphasis>-<Emphasis Type="Italic">japonici</Emphasis>

Powdery mildew caused by Erysiphe euonymi-japonici (Eej) is an increasingly serious fungal disease on Euonymus japonicus that is an important ornamental plant. However, little is currently known about infection and pathogenesis of Eej on E. japonicus. Here, we report plant infection by Eej at the histological and cytological levels. Eej caused severe disease symptoms with white and snow-like colonies on leaf surfaces of E. japonicus. Microscopic observations were conducted continuously to define infection process of Eej on E. japonicus. Eej conidia germinated to produce appressorial germ tubes on leaf surfaces and formed irregular haustoria in plant epidermal cells at 6 h post-inoculation (hpi) and 12 hpi, respectively. After uptaking nutrients from host cells by haustoria, Eej formed numerous hyphae and extensive colonization on leaf surfaces at 96 hpi and finally produced abundant conidiophores and new conidia on leaf surfaces at 168 hpi. In addition, there was consistently a single nucleus in different Eej infection structures and haustorial development could be divided into three major stages, including formation of penetration peg, formation of haustorial neck and initial haustorium, and maturation of haustorium. These results provide useful information for further determination of Eej pathogenesis and finally controlling the disease.     

Comparative analysis of otolith morphology in three species of <Emphasis Type="Italic">Scomber</Emphasis>

Geometric morphometrics is a quick and reliable approach to differentiate fish stocks based on the variation of otolith shapes. In this study, morphometric analysis of otolith shapes was used to differentiate three species of Scomber. The sagittae morphology of S. scombrus otolith is totally different from that of S. japonicus and S. australasicus. Multivariate analysis consistently showed that S. japonicus was morphologically similar to S. australasicus, whereas a significant difference in otolith shapes was detected between S. scombrus and other two species of Scomber. The rostrum, antirostrum, excisural notch and dorsal-posterior margin of the otolith reflect the main variations between the three species of Scomber. Shape indices and Fourier coefficients were used to discriminate fish species using analysis of variance and Fisher discriminant analysis. The shape indices successfully differentiated 100%, 95.7% and 96.4% of otoliths in S. japonicus, S. australasicus and S. scombrus, respectively, while the Fourier coefficients only discriminated 70.0%, 61.9% and 91.3% of the sagittae in S. japonicus, S. australasicus and S. scombrus. This study indicates that the shape analysis on the sagittae morphometrics of otoliths is a better method to differentiate species of Scomber.     

Effects of alien invasion by <Emphasis Type="Italic">Bombus terrestris</Emphasis> L. (Apidae) on the visitation patterns of native bumblebees in coastal plants in northern Japan

When alien pollinator species enter a native community of pollinators in which resource partitioning has been established, the pollination network between plants and pollinators may be modified through the interactions between the pollinators over the use of floral resources. We observed the floral-use patterns of native (Bombus hypocrita and B. deuteronymus) and alien (B. terrestris) bumblebee species in a coastal grassland in northern Japan. We analyzed the factors determining resource partitioning patterns. B. hypocrita tended to visit flowers with shallow or wide open corollas, such as Rosa rugosa, whereas B. deuteronymus visited flowers with complex or deeper corollas, such as Lathyrus japonicus. Given the wider floral preference of B. terrestris, floral use by the alien bumblebees consistently overlapped with that of native bumblebees. The visitation of B. terrestris to R. rugosa flowers was positively correlated with that of B. hypocrita. These bumblebee species frequently used similar floral resources, in part because of the large overlap in the seasonality of their foraging activity. The visitation frequency of B. deuteronymus to L. japonicus flowers was independent of the visitation frequency of other bumblebee species. The major visitation periods of the bumblebees to L. japonicus flowers reciprocally differed between B. deuteronymus and B. terrestris, suggesting phenological resource partitioning between these species. Our study suggests that phenological niche partitioning is more common in specialized flowers (L. japonicus) than in generalized flowers (R. rugosa).     

A new Taqman<Superscript>©</Superscript> PCR-based method for the detection and identification of scyphozoan jellyfish polyps

While blooms of large scyphomedusae and cubomedusae receive most public attention owing to effects on tourism (e.g., stinging swimmers), commerce, and fisheries, relatively little attention is given to the inconspicuous benthic polypoid stage. This is particularly troubling when considering the widespread translocation of some invasive marine jellyfish. The transport of benthic polyps (via ships, barges, and offshore drilling platforms) is theorized to be the most likely way in which invasive jellies are globally transported. Yet given the extremely small size and cryptic nature of most benthic polyps, identifying and tracking them in the field amongst the larger communities of fouling organisms is extremely difficult. To this end, we have developed a rapid molecular assay for detecting benthic jellyfish polyps from three scyphozoan genera in the Gulf of Mexico. One of these (Phyllorhiza spp.) is an invasive scyphozoan established in the Gulf of Mexico and is theorized to have been spread worldwide as a fouling organism on the hulls of cargo ships, while the other two (U.S. Chrysaora sp. and Gulf of Mexico Aurelia spp.) are local blooming animals that have shown recent numerical increases in the Gulf of Mexico. This method involves a multiplex Real-Time Polymerase Chain Reaction (PCR) assay using Taqman^© probes that can be run on DNA extracted from whole-community scrapings of benthic surfaces, such as boat hulls, dock pilings, oilrigs, and settling plates. Specificity tests indicated that all Taqman^© probes were successful against all individuals of target taxa, but not against 17 non-target local and worldwide scyphozoan and hydrozoan species. Tests showed all probes to be extremely sensitive, reacting to as few as 50 copies of template DNA, with one (Chrysaora sp.) reacting to as few as 10 copies. The assay correctly identified individual polyps of Aurelia sp. and Chrysaora sp. The use of this Taqman^© assay on tissue collected from whole benthic scrapings should allow screening of incoming ships to the Gulf of Mexico for the invasive P. punctata, and locating and studying the cryptic benthic stages of northern Gulf of Mexico jellyfish, which will lead to a better understanding of the overall population distribution and bloom dynamics of medusae.     

Review of the <Emphasis Type="Italic">Ostichthys japonicus</Emphasis> complex (Beryciformes: Holocentridae: Myripristinae) in the northwestern Pacific Ocean,with description of a new species

A taxonomic review of the northwestern Pacific Ocean members of the Ostichthys japonicus complex (Holocentridae: Myripristinae), defined by 3.5 scale rows between the lateral line and spinous dorsal-fin base, recognized three valid species: Ostichthys alamai sp. nov., Ostichthys hypsipterygion Randall, Shimizu and Yamakawa 1982 and Ostichthys japonicus (Cuvier in Cuvier and Valenciennes 1829). Ostichthys alamai, based on 10 specimens (118–179 mm SL) from Panay Island, the Philippines and Sulawesi, Indonesia, is similar to O. hypsipterygion in having longitudinal rows of white spots laterally on the body, but has 17 or 18 (modally 17) pectoral-fin rays [vs. 15 or 16 (15) in the latter], the last dorsal-fin spine fused to the first dorsal-fin soft ray (vs. spine and ray separated), and no white blotch on the pectoral-fin base (vs. white blotch present). It differs from O. japonicus, also occurring in the Philippines, in having relatively longer dorsal- and anal-fin spines, a greater number of well-developed long spinules on the body scales, and rows of white spots laterally on the body (vs. generally absent). Detailed comparisons of O. alamai with other members of the complex are made, and revised diagnoses given for O. hypsipterygion and O. japonicus. Ostichthys sheni Chen, Shao and Mok 1990 and Holotrachys major Whitley 1950 are both regarded as junior synonyms of O. japonicus.     

Polysaccharide degradation systems of the saprophytic bacterium <Emphasis Type="Italic">Cellvibrio japonicus</Emphasis>

Study of recalcitrant polysaccharide degradation by bacterial systems is critical for understanding biological processes such as global carbon cycling, nutritional contributions of the human gut microbiome, and the production of renewable fuels and chemicals. One bacterium that has a robust ability to degrade polysaccharides is the Gram-negative saprophyte Cellvibrio japonicus. A bacterium with a circuitous history, C. japonicus underwent several taxonomy changes from an initially described Pseudomonas sp. Most of the enzymes described in the pre-genomics era have also been renamed. This review aims to consolidate the biochemical, structural, and genetic data published on C. japonicus and its remarkable ability to degrade cellulose, xylan, and pectin substrates. Initially, C. japonicus carbohydrate-active enzymes were studied biochemically and structurally for their novel polysaccharide binding and degradation characteristics, while more recent systems biology approaches have begun to unravel the complex regulation required for lignocellulose degradation in an environmental context. Also included is a discussion for the future of C. japonicus as a model system, with emphasis on current areas unexplored in terms of polysaccharide degradation and emerging directions for C. japonicus in both environmental and biotechnological applications.     

Rare triterpene glycoside of ginseng (ginsenoside malonyl-Rg<Subscript>1</Subscript>) detected in plant cell suspension culture of <Emphasis Type="Italic">Panax japonicus</Emphasis> var. <Emphasis Type="Italic">repens</Emphasis>

This paper reports for the first time about the detection and identification of ginsenoside malonyl-Rg₁ (the rare 20(S)-protopanaxatriol-type ginsenoside) in the biomass of plant cell suspension culture of Japanese ginseng (Panax japonicus C.A. Mey. var. repens). Ginsenosides were analyzed by means of high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) in positive-ion mode. Malonyl-Rg1 was identified as a result of interpretation of MS spectra obtained upon fragmentation of protonated molecular ion ([M + H]⁺) of this compound in an ionization source. Chromatographic analysis and MS spectra showed that the cells of P. japonicus var. repens cultivated in vitro contain several isomers of malonyl-Rg₁. Thus, we ascertained for the first time that, in addition to malonyl ginsenosides of 20(S)-protopanaxadiol group, the plant cell culture of ginseng P. japonicus var. repens can accumulate glycosides of 20(S)-protopanaxatriol group acylated with a malonic acid residue. The obtained results showed that, in the cells of ginseng cultivated in vitro for a long time (for 10 years and more), the assortment of secondary metabolites (ginsenosides) may be as wide as in intact plants.     

Does allelopathy affect co-culturing <Emphasis Type="Italic">Haslea ostrearia</Emphasis> with other microalgae relevant to aquaculture?

Haslea ostrearia is a marine diatom known to produce marennine, a water-soluble blue-green pigment responsible for the greening of oysters in ponds along the French Atlantic coast. This phenomenon occurs seasonally when H. ostrearia blooms in oyster ponds, and it increases the economic value of cultured oysters. From an ecological perspective, H. ostrearia blooms are accompanied by a decrease in the abundance of other microalgae, suggesting that this diatom produces allelochemicals. Recent studies showed that purified marennine has other biological activities, for instance antioxidant, antibacterial, and antiviral activities, which could be used in aquaculture to promote this pigment as a natural antipathogen agent. One important issue regarding the possible use of H. ostrearia in aquaculture as a mixed algal diet, however, is the importance of marennine allelopathy. In this study, we investigated the allelopathic effect of H. ostrearia on the growth of five microalgal species relevant to aquaculture: Chaetoceros calcitrans, Skeletonema costatum, Phaeodactylum tricornutum, Tetraselmis suecica, and Tisochrysis lutea. Allelopathic tests were realized by co-culturing these microalgae with H. ostrearia in batch and in semi-continuous mode, based on initial biovolume ratios. Our findings showed that inhibition of the growth of microalgae due to the presence of H. ostrearia and marennine was species dependent. Skeletonema costatum, C. calcitrans, and T. lutea were significantly more sensitive, whereas T. suecica and P. tricornutum appeared to be more resistant. Growth irradiance significantly influenced the allelopathic effect against the sensitive species S. costatum, and the H. ostrearia production of marennine increases with irradiance. Data presented in this study partly support the hypothesis that marennine released into the culture medium possibly acts as an allelochemical compound, thus explaining the dominance of H. ostrearia and the loss of sensitive algae in oyster ponds, but also that some species are insensitive, which allows co-culturing and use in a mixed algal diet in aquaculture.     

Environmental factors inducing the transformation of polyp into medusae in <Emphasis Type="Italic">Aurelia aurita</Emphasis> (Scyphozoa)

The transformation of polyp into medusa is one of the most interesting processes in the life cycle of cnidarians. In the polyps of the class Scyphozoa this transformation occurs in the form of strobilation, which is the transverse fission of polyps with the formation of discoidal ephyrae. At present, the endogenous regulation of strobilation in one of scyphozoans, Aurelia aurita, is being investigated by the methods of molecular biology (Fuchs et al., 2014). However, it is still unclear which key environmental factors induce this process. The main purposes of this review are to summarize the literature data on the conditions in which strobilation in A. aurita occurs in nature and in the laboratory and to try to identify the environmental factors that are most likely to play a signaling role in strobilation.     

Occurrence of two types of larvae of the Asian seaperch (<Emphasis Type="Italic">Lateolabrax</Emphasis>) in the estuaries of northern Vietnam

Lateolabrax sp. larvae were collected in the Tien Yen and Kalong estuaries of northern Vietnam, the southernmost locality for this genus distribution. Vietnamese Lateolabrax sp. larvae could be distinguished from those of L. japonicus by pigmentation patterns. Their morphological, meristic and pigmentation characters were closer to those of Chinese Lateolabrax than L. japonicus, so Vietnamese Lateolabrax is likely situated as a population of the Chinese one. Morphometric and pigmentation characters of larvae from the two estuaries differed, suggesting that Lateolabrax of northern Vietnam are diversified and consist of at least two different breeding stocks.     

Associations of large jellyfish distributions with temperature and salinity in the Yellow Sea and East China Sea

Climate change may contribute to the increasing frequency and intensity of jellyfish blooms around the world. To test the null hypotheses that distributions did not differ among species of jellyfish or according to temperature salinity, we sampled large jellyfishes using bottom trawl surveys during 2006–2007 in the Yellow Sea (YS) and East China Sea (ECS). The total biomass of large jellyfish in the YS was low in April 2006 in cool waters, increased with warming waters, peaked in early September 2006 (22,891 ± 25,888 kg km^–2), and then decreased with cooling to minimal biomass during March 2007. During its peak early September 2006, Nemopilema nomurai was relatively eurythermal and distributed throughout the YS. Cyanea spp. occurred in warmer waters and attained maximum biomass in May 2007 in the ECS. Ulmaridae, which preferred colder temperatures, reached maximum biomass in October 2006 and occurred mainly in the central YS. Aequorea spp. usually occurred in colder waters, with maximum biomass in May 2007 mainly north of 30°N. Our analyses suggest that environmental preferences of the large jellyfish may enable prediction of jellyfish population sizes and distributions in Chinese waters, which is essential in order to address ecological problems caused by large jellyfish blooms in East Asia Waters.     

The lateral line system and its innervation in <Emphasis Type="Italic">Lateolabrax japonicus</Emphasis> (Percoidei <Emphasis Type="Italic">incertae sedis</Emphasis>) and two apogonids (Apogonidae), with special reference to superficial neuromasts (Teleostei: Percomorpha)

The lateral line system and its innervation were examined in a generalized perch-like species, Lateolabrax japonicus (Percoidei incertae sedis), and compared with those in two species of Apogonidae (Fowleria variegata in Apogonichthyini and Ostorhinchus doederleini in Ostorhinchini) characterized by proliferated superficial neuromasts (SNs) on the head, trunk lateral line scales and caudal fin. The total number of SNs differed greatly between the two groups, being 271 in the former, and 2,403 and 4,088 in the latter. The mandibular ramus (MDR) was extensively ramified in the head of the apogonids, with three additional branches that were absent in L. japonicus, innervating 1,117 SNs in F. variegata and 1,928 in O. doederleini. In the apogonids, the additional anterodorsal branch of the MDR coursed parallel to the buccal ramus anteriorly (on the interorbital space) and to the supratemporal ramus posteriorly (on the temporal region). The two parallel portions supplied numerous SN rows forming a characteristic crosshatch pattern, the branch and two rami distributing to transverse and longitudinal rows, respectively. In the two groups, the trunk lateral line scales each housed a canal neuromast (CN; partly replaced by an SN in F. variegata). In addition, one to four (in L. japonicus) and three to 55 (in the apogonids) SNs occurred on each lateral line scale, the pattern of SN innervation being identical in having two types of branches; one innervated a CN and SNs, and the other SN(s) only. The latter type extended only to a limited number of scales in L. japonicus, but to nearly all or all scales in the apogonids. Compared with F. variegata, branches of the respective types were more finely ramified with greater number of SNs in O. doederleini.     

Gut bacterial diversity of farmed sea cucumbers <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> with different growth rates

Farmed sea cucumbers (Apostichopus japonicus) of the same age displayed significantly different body sizes and weights under the same farming conditions. To examine the gut bacterial diversity of sea cucumbers and whether the growth differences between them were related to intestinal microbiota, the bacterial species from intestinal samples of 30 farmed A. japonicus from the same tank (15 large sea cucumbers vs. 15 small sea cucumbers) were characterized based on 16S rRNA gene analysis by means of high throughout sequencing. The results showed that bacterial phylotypes in both sizes of sea cucumbers were closely related to Proteobacteria, Verrucomicrobia, Bacteroidetes, Actinobacteria, Firmicutes, Cyanobacteria, Planctomycete, and Spirochaetes, of which Proteobacteria were predominant (>50%). There were no significant differences in the relative abundances of each bacterial phylotype between the two groups, except for Actinobacteria (P < 0.05). In addition, different species uniquely belonging to all three tested samples in the large group and the small group were found. It was interestingly that Vibrio were absent from both groups. It is likely that the differences in the abundances of Actinobacteria and different species in the two groups may be related to their remarkable disparities in body sizes.     

LjCOCH interplays with LjAPP1 to maintain the nodule development in <Emphasis Type="Italic">Lotus japonicus</Emphasis>

Legume plants develop nodules during their symbiotic interaction with rhizobia, and much progress has been made towards understanding Nod factor perception and downstream signaling pathways, while our knowledge about the maintenance of nodule organogenesis was limited. We report here the knockdown mutants of LjCOCH, an ortholog of COCHLEATA in Pisum sativum, cause severe defects in nodule organogenesis in Lotus japonicus. The mature nodule number was drastically decreased accompanied with abnormal lenticel and vascular bundle developmental defects, but not produce roots from nodules in both Ljcoch mutants and LjCOCH-RNAi transgenic hairy roots. LjAPP1, a membrane-associated soluble aminopeptidase P1, was identified to interact with LjCOCH through yeast two-hybrid screening. Unlike that of Ljcoch mutants, insertion mutants of LjAPP1 and LjAPP1-RNAi transgenic hairy roots showed increased nodule number, while the lenticel and vascular development were not affected. Gene expression analysis indicated that LjCOCH and LjAPP1 were differentially upregulated by rhizobia inoculation, and LjNF-YA1 was the major downstream target of LjCOCH and LjAPP1. Our findings suggested that LjCOCH acts as a key factor involved in determinate nodule development through direct interaction with LjAPP1 to regulate the expression of LjNF-YA1, opposite effects of LjCOCH and LjAPP1 provide a dynamic regulation of nodule development in L. japonicus.     

Features of expression of the <Emphasis Type="Italic">PsSst1</Emphasis> and <Emphasis Type="Italic">PsIgn1</Emphasis> genes in nodules of pea (<Emphasis Type="Italic">Pisum sativum</Emphasis> L.) symbiotic mutants

The sequences of the PsSst1 and PsIgn1 genes of pea (Pisum sativum L.) homologous to the symbiotic LjSST1 and LjIGN1 genes of Lotus japonicus (Regel.) K. Larsen are determined. The expression level of PsSst1 and PsIgn1 genes is determined by real-time PCR in nodules of several symbiotic mutants and original lines of pea. Lines with increased (Sprint-2Fix^– (Pssym31)) and decreased (P61 (Pssym25)) expression level of both genes are revealed along with the lines characterized by changes in the expression level of only one of these genes. The revealed features of the PsSst1 and PsIgn1 expression allow us to expand the phenotypic characterization of pea symbiotic mutants. In addition, PsSst1 and PsIgn1 cDNA is sequenced in selected mutant lines, characterized by a decreased expression level of these genes in nodules, but no mutations are found.