Screening for bacterial-fungal associations in a south-eastern US salt marsh using pre-established fungal monocultures

Both bacteria and fungi play critical roles in decomposition processes in many natural environments, yet only rarely have they been studied as an integrated community. We examined whether physical associations exist between individual bacterial and fungal species that co-occur on decaying smooth cordgrass, Spartina alterniflora, in a south-eastern US salt marsh. Fungal-pervaded decaying Spartina was used as "bait" for potential bacterial associates. The bundles (infiltrated with one of three dominant fungal members of the decomposer assemblage, or an autoclaved control) were placed in a salt marsh and collected biweekly for 6 weeks during the first experiment (late summer 2002), and weekly for 3 weeks during the second experiment (early summer 2003). Terminal-restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes was used to track colonization by bacterial taxa in association with the established fungal species. T-RFLP analysis of 18S-to-28S internal transcribed spacer (ITS) regions was used to monitor changes in fungal communities once bundles had been placed in the field. Results from both years were nearly identical, and showed that invasion by fungi other than the bait species was slow, resulting in a virtual fungal monoculture for several weeks into the experiments. Surprisingly, bacterial communities were unaffected by the identity of the fungal bait. Regardless of the fungal species, and even in the absence of prior fungal colonization, bacterial 16S rRNA profiles were remarkably similar. These results suggest that few species-specific associations, either positive or negative, exist between bacterial and fungal members of the Spartina decomposer community during initial colonization.     

Species of Pseudorhabdosynochus Yamaguti, 1958 (Monogenea: Diplectanidae) from Epinephelus fasciatus and E. merra (Perciformes: Serranidae) off New Caledonia and other parts of the Indo-Pacific Ocean, with a comparison of measurements of specimens prepared using different methods, and a description of P. caledonicus n. sp.

Species of Pseudorhabdosynochus were studied from fresh specimens collected from Epinephelus fasciatus and E. merra off New Caledonia, South Pacific, and specimens deposited in Museums. Experiments on two species demonstrated that the sclerotised hollow organs, such as the quadriloculate male copulatory organ and the vagina, may show differences in measurements of up to 50% when flattened. P. caledonicus n. sp. is described from E. fasciatus in New Caledonia, on which it is relatively rare; it is distinguished on the basis of the quadriloculate organ, which has a very thin anterior wall, the sclerotised parts of the vagina in form of a straight tube with a star-shaped lateral structure, and the squamodiscs composed of 11 open rows of rodlets. P. cupatus (Young, 1969) is redescribed from abundant material from E. fasciatus off New Caledonia (new geographical record) and compared with paratype specimens from Australia (from E. fasciatus and E. merra) and specimens from E. fasciatus in the Red Sea (both herein redescribed and figured); a specimen was also found on a slide from E. merra off Vanuatu. P. melanesiensis (Laird, 1958) is redescribed from material from E. merra off New Caledonia (new geographical record) and compared with type-specimens (herein redescribed and figured) from the same host off Vanuatu. The structure of the sclerotised vagina in P. cupatus and P. melanesiensis is very similar, with a thin-walled tube and a heavily sclerotised structure with three loculi. P. vagampullum (Young, 1969) is redescribed from the paratypes from E. merra from Australia, but was not found in New Caledonia; specimens included among its paratypes (from E. merra in Australia), but different, are herein attributed to Pseudorhabdosynochus sp. 3. P. lantauensis (Beverley-Burton & Suriano, 1981) is redescribed from the paratype specimens from E. longispinis off Hong-Kong. A specimen found among the paratypes of P. cupatus belongs to a different species, herein designated as Pseudorhabdosynochus sp. 1. Specimens from E. longispinis off Hong-Kong, previously attributed to P. cupatus, are attributed to another species, Pseudorhabdosynochus sp. 2. The three species P. cupatus, Pseudorhabdosynochus sp. 1 and Pseudorhabdosynochus sp. 2 have in common a 'lamellosquamodisc' composed of central telescopic lamellae and peripheral rows of rodlets; they can be distinguished by the shape of the sclerotised vagina and measurements of the haptoral hard-parts. Specimens from E. longispinis off Hong-Kong, previously attributed to P. vagampullum, probably belong to a different species. Consequently, after these modified determinations, P. cupatus parasitises only E. fasciatus and E. merra, and P. melanesiensis and P. vagampullum parasitise only E. merra. With their wide geographical distribution and different species of Pseudorhabdosynochus in different localities, E. fasciatus and E. merra appear to represent excellent models for investigating monogenean biogeography in the Indo-Pacific Ocean.     

Two anisakid nematodes from marine fishes off New Caledonia, including Raphidascaris (Ichthyascaris) nemipteri n. sp. from Nemipterus furcosus

One new and one known species of the ascaridoid family Anisakidae are reported from marine fishes off the southwestern coast of New Caledonia: Raphidascaris (Ichthyascaris) nemipteri n. sp. from the intestine of the forked-tailed threadfin bream Nemipterus furcosus (Nemipteridae, Perciformes) and Hysterothylacium cenaticum (Bruce & Cannon, 1989) from the intestine of the striped marlin Tetrapturus audax (Istiophoridae, Perciformes). R. nemipteri is characterised mainly by the shape (wider than long) of the lips, the length of the spicules (225–399 μm, which represent 2.7–4.2% of the body length), the number (22–33) of caudal pre-anal papillae, the position of the vulva (at 16–20% of the body length), and the presence of cuticular spines on the tip of the female tail. Specimens of H. cenaticum from New Caledonia generally exhibited smaller body measurements than those originally described from Australian waters; the deirids and eggs are described for the first time. Maricostula Bruce & Cannon, 1989 is considered a junior synonym of Hysterothylacium, to which three species are transferred as H. cenaticum (Bruce & Cannon, 1989) n. comb., H. makairi (Bruce & Cannon, 1989) n. comb. and H. tetrapteri (Bruce & Cannon, 1989) n. comb.     

The NeuC protein of Escherichia coli K1 is a UDP N-acetylglucosamine 2-epimerase

The K1 capsule is an essential virulence determinant of Escherichia coli strains that cause meningitis in neonates. Biosynthesis and transport of the capsule, an alpha-2,8-linked polymer of sialic acid, are encoded by the 17-kb kps gene cluster. We deleted neuC, a K1 gene implicated in sialic acid synthesis, from the chromosome of EV36, a K-12-K1 hybrid, by allelic exchange. Exogenously added sialic acid restored capsule expression to the deletion strain (DeltaneuC), confirming that NeuC is necessary for sialic acid synthesis. The deduced amino acid sequence of NeuC showed similarities to those of UDP-N-acetylglucosamine (GlcNAc) 2-epimerases from both prokaryotes and eukaryotes. The NeuC homologue from serotype III Streptococcus agalactiae complements DeltaneuC. We cloned the neuC gene into an intein expression vector to facilitate purification. We demonstrated by paper chromatography that the purified neuC gene product catalyzed the formation of [2-(14)C]acetamidoglucal and [N-(14)C]acetylmannosamine (ManNAc) from UDP-[(14)C]GlcNAc. The formation of reaction intermediate 2-acetamidoglucal with the concomitant release of UDP was confirmed by proton and phosphorus nuclear magnetic resonance spectroscopy. NeuC could not use GlcNAc as a substrate. These data suggest that neuC encodes an epimerase that catalyzes the formation of ManNAc from UDP-GlcNAc via a 2-acetamidoglucal intermediate. The unexpected release of the glucal intermediate and the extremely low rate of ManNAc formation likely were a result of the in vitro assay conditions, in which a key regulatory molecule or protein was absent.     

Gilquiniid cestodes (Trypanorhyncha) from elasmobranch fishes off New Caledonia with descriptions of two new genera and a new species

Cestodes were collected from deep-sea sharks caught off New Caledonia, South Pacific. Vittirhynchus squali n. g., n. sp. (Trypanorhyncha: Gilquiniidae) is described from the spiral valve of Squalus melanurus Fourmanoir & Rivaton. The new genus possesses four bothria and a typical heteroacanthous metabasal armature but has a file of three macrohooks forming a short chainette on the internal surface of the basal armature. Sagittirhynchus aculeatus n. g., n. sp., from the spiral valve of Centrophorus sp. (undescribed), also has four bothria and a typical heteroacanthous armature but lacks a distinctive basal swelling and has the final hooks of each principal row prominently enlarged. Gilquinia minor n. sp., from the spiral valve of Centrophorus sp. (undescribed), is distinguished by the presence of only five hooks per principal row compared with eight in congeners. Gilquinia sp. is reported from Squalus melanurus. G. robertsoni Beveridge, 1990 is reported from S. megalops (Macleay).     

Thaumatocotyle pseudodasybatis Hargis, 1955 (Monogenea: Monocotylidae) from Aetobatus cf. narinari, with a comparison of specimens from Australia, French Polynesia and New Caledonia

Thaumatocotyle pseudodasybatis Hargis, 1955, has previously been described from Aetobatus narinari in the Atlantic and subsequently recorded from the Pacific. Aetobatus cf. narinari is now considered a species complex; as monocotylids are often strictly species specific, we test the hypothesis that detailed examination of specimens of monocotylids from rays from various localities could reveal morphological differences and eventually help our understanding of the systematics of the host. T. pseudodasybatis, previously known from seven specimens only, is redescribed from an additional 26 specimens from the South Pacific (off New Caledonia, Australia and Ranguiroa, French Polynesia), all from Aetobatus cf. narinari. The female reproductive organs are described in detail. The distal extremity of the male sclerotised copulatory organ, described in detail for the first time, shows a characteristic pattern of longitudinal striations on its edge that might be useful for future distinction from other species. The development of the male and female organs in juveniles is described, showing that growth of the male sclerotised copulatory organ begins with its basal part and precedes development of the ejaculatory bulb. Specimens from New Caledonia, Australia and French Polynesia had similar measurements and morphology, especially in the shape of the distal end of the male sclerotised copulatory organ; they were also similar to the holotype from the Atlantic. This suggests that all specimens from the Pacific and Atlantic belong to a single species; T. pseudodasybatis thus cannot be used to differentiate populations of Aetobatus cf. narinari, perhaps because this monocotylid is not strictly species-specific.

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Résumé Thaumatocotyle pseudodasybatis Hargis, 1955 a été décrit d’Aetobatus narinari dans l’Atlantique, et plus tard retrouvé dans le Pacifique. Aetobatus cf. narinari est maintenant considéré comme un complexe d’espèces. Parce que les Monocotylidae sont souvent strictement spécifiques de leur espèce-hôte, nous testons l’hypothèse qu’un examen détaillé des spécimens de Monocotylidae de raies de localités variées pourrait révéler des différences morphologiques et finalement aider à comprendre la systématique de l’hôte. T. pseudodasybatis, connu précédemment par seulement sept spécimens, est redécrit à partir de 26 spécimens supplémentaires de l’Océan Pacifique Sud (Nouvelle-Calédonie, Australie, et Ranguiroa, Polynésie Française), tous de Aetobatus cf. narinari. Les organes reproducteurs femelles sont décrits en détail. L’extrémité distale de l’appareil copulateur sclérifié mâle, décrite en détail pour la première fois, montre un patron caractéristique de striations longitudinales sur son bord, qui pourrait être utile à l’avenir pour différencier cette espèce. Le développement des organes mâles et femelles chez les juvéniles est décrit; cela montre que la croissance de l’appareil copulateur sclérifié mâle commence par son extrémité basale et précède le développement du bulbe éjaculateur. Les spécimens de Nouvelle-Calédonie, Australie et Polynésie Française ont une morphologie et des mensurations similaires, en particulier pour la forme de l’extrémité distale de l’appareil copulateur sclérifié mâle. Ils sont aussi similaires à l’holotype, qui vient de l’Atlantique. Ceci suggère que tous les spécimens du Pacifique et de l’Atlantique appartiennent à une même espèce. T. pseudodasybatis ne peut donc pas être utilisé pour différencier les populations d’Aetobatus cf. narinari, peut-être parce que ce Monocotylidae n’est pas strictement spécifique.

     

Three nematode species from elasmobranchs off New Caledonia

Nematode specimens of three species, Terranova scoliodontis (Baylis, 1931) (Ascaridida, Anisakidae), Echinocephalus sinensis Ko, 1975 and E. overstreeti Deardorff & Ko, 1983 (both Spirurida, Gnathostomatidae) were collected from the tiger shark Galeocerdo cuvier, the ray Aetobatus cf. narinari and the blotched fantail ray Taeniura meyeni, respectively, from the coastal waters of New Caledonia, South Pacific. Their examination, including scanning electron microscopy (SEM), made it possible to obtain some new data on their morphology, e.g. in relation to the number and arrangement of male caudal papillae in T. scoliodontis and both Echinocephalus spp., the presence of ventral cuticular ornamentations in T. scoliodontis and the number of transverse spines on the cephalic bulb in Echinocephalus spp. All these species are reported for the first time from New Caledonian waters and G. cuvier is a new host species for T. scoliodontis. SEM examination of the fourth-stage larvae of E. overstreeti from the type-host showed the presence of anterior dorsal and ventral groups of minute spines on the cephalic bulb to be an important taxonomic feature for␣the interspecific distinction of Echinocephalus larvae and questions previous data on the occurrence of E. overstreeti larvae in many elasmobranch fishes and molluscs in Australian waters.

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Résumé Des Nématodes appartenant à trois espèces, Terranova scoliodontis (Baylis, 1931) (Ascaridida, Anisakidae), Echinocephalus sinensis Ko, 1975 et E. overstreeti Deardorff & Ko, 1983 (tous deux Spirurida, Gnathostomatidae) ont été collectés respectivement du requin tigre Galeocerdo cuvier et des raies Aetobatus cf. narinari et Taeniura meyeni, des eaux côtières de Nouvelle-Calédonie, Pacifique Sud. Leur étude, en particulier en microscopie électronique à balayage (MEB) a permis d’obtenir de nouvelles informations sur leur morphologie, par exemple sur le nombre et la disposition des papilles caudales mâles chez T. scoliodontis et␣les deux espèces d’Echinocephalus, la présence d’ornementations cuticulaires ventrales chez T. scoliodontis, et le nombre d’épines transversales sur le bulbe céphalique des Echinocephalus. Toutes ces espèces sont mentionnées pour la première fois des eaux de Nouvelle-Calédonie et G. cuvier est un nouvel hôte pour T.␣scoliodontis. L’examen au MEB de la larve de quatrième stade d’E. overstreeti, provenant de l’hôte-type, a montré que les groupes antérieurs et postérieurs de petites épines sur le bulbe céphalique sont un caractère taxonomique important pour la distinction interspécifique des larves d’Echinocephalus et met en doute des informations antérieures sur la présence de larves d’E. overstreeti chez de nombreux Élasmobranches et Mollusques des eaux d’Australie.

     

The pattern of clinical breast cancer metastasis correlates with a single nucleotide polymorphism in the C1qA component of complement

Complement is one of primary defense mechanisms against intravascular microorganisms and could play a role in the immune response to malignancy and hence its clinical behavior. We evaluated if the sole coding polymorphism of C1qA associates with outcome in patients with breast carcinoma. Genotyping for C1qA_[276A/G] was performed in 63 breast cancer subjects with localized tumor and compared with that in 38 breast cancer subjects with metastasis. Established risk factors for clinical outcome were considered and evaluated in multivariable analysis. Breast cancer subjects with heterozygous or homozygous C1qA_[276G] genotype had a higher rate of metastasis than subjects with the homozygous C1qA_[276A] genotype [hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.1–4.1]. This association was stronger when only metastatic sites associated with hematogenous spread, i.e., to the bone, liver, and brain, were considered (HR 3.5, 95% CI 1.4–5.6) and remained statistically significant after adjustment for the number of positive lymph nodes, estrogen receptor status, and progesterone receptor status. There was no statistical difference in the C1qA_[276A/G] allelic distribution between all subjects with breast cancer and controls. These results suggest there could be an association of a single nucleotide polymorphism at position 276 of the C1qA component of complement with breast cancer metastasis to sites linked to hematogenous spread of disease. The C1qA polymorphism associated with decreased distant metastasis has also been correlated with an increased incidence of subcutaneous systemic lupus and C1q deficiencies, suggesting that an altered immune response may play a role in the observed association. Supported in part by National Institute of Health grant R21-CA90822, Friends You Can Count On! grant 1-87093-00, and the Woody and Louise White Cancer Research Fund.     

Thermodynamic stability, unfolding kinetics, and aggregation of the N-terminal actin-binding domains of utrophin and dystrophin

Muscular dystrophy (MD) is the most common genetic lethal disorder in children. Mutations in dystrophin trigger the most common form of MD, Duchenne, and its allelic variant Becker MD. Utrophin is the closest homologue and has been shown to compensate for the loss of dystrophin in human disease animal models. However, the structural and functional similarities and differences between utrophin and dystrophin are less understood. Both proteins interact with actin through their N-terminal actin-binding domain (N-ABD). In this study, we examined the thermodynamic stability and aggregation of utrophin N-ABD and compared with that of dystrophin. Our results show that utrophin N-ABD has spectroscopic properties similar to dystrophin N-ABD. However, utrophin N-ABD has decreased denaturant and thermal stability, unfolds faster, and is correspondingly more susceptible to proteolysis, which might account for its decreased in vivo half-life compared to dystrophin. In addition, utrophin N-ABD aggregates to a lesser extent compared with dystrophin N-ABD, contrary to the general behavior of proteins in which decreased stability enhances protein aggregation. Despite these differences in stability and aggregation, both proteins exhibit deleterious effects of mutations. When utrophin N-ABD mutations analogous in position to the dystrophin disease-causing mutations were generated, they behaved similarly to dystrophin mutants in terms of decreased stability and the formation of cross-β aggregates, indicating a possible role for utrophin mutations in disease mechanisms.     

Fish oil prevents high-saturated fat diet-induced impairments in adiponectin and insulin response in rodent soleus muscle

High saturated fatty acid (SFA) diets contribute to the development of insulin resistance, whereas fish oil-derived n-3 polyunsaturated fatty acids (PUFA) increase the secretion of adiponectin (Ad), an adipocyte-derived protein that stimulates fatty acid oxidation (FAO) and improves skeletal muscle insulin response. We sought to determine whether fish oil could prevent and/or restore high SFA diet-induced impairments in Ad and insulin response in soleus muscle. Sprague-Dawley rats were fed 1) a low-fat control diet (CON group), 2) high-SFA diet (SFA group), or 3) high SFA with n-3 PUFA diet (SFA/n-3 PUFA group). At 4 wk, CON and SFA/n-3 PUFA animals were terminated, and SFA animals were either terminated or fed SFA or SFA/n-3 PUFA for an additional 2 or 4 wk. The effect of diet on Ad-stimulated FAO, insulin-stimulated glucose transport, and expression of Ad, insulin and inflammatory signaling proteins was determined in the soleus muscle. Ad stimulated FAO in CON and 4 wk SFA/n-3 PUFA (+36%, +39%, respectively P ≤ 0.05) only. Insulin increased glucose transport in CON, 4 wk SFA/n-3 PUFA, and 4 wk SFA + 4 wk SFA/n-3 PUFA (+82%, +33%, +25%, respectively P ≤ 0.05); this effect was lost in all other groups. TLR4 expression was increased with 4 wk of SFA feeding (+24%, P ≤ 0.05), and this was prevented in 4 wk SFA/n-3 PUFA. Suppressor of cytokine signaling-3 expression was increased in SFA and SFA/n-3 PUFA (+33 and +18%, respectively, P ≤ 0.05). Our results demonstrate that fish oil can prevent high SFA diet-induced impairments in both Ad and insulin response in soleus muscle.