'Cand. Actinochlamydia clariae' gen. nov., sp. nov., a Unique Intracellular Bacterium Causing Epitheliocystis in Catfish (Clarias gariepinus) in Uganda

Background and Objectives: Epitheliocystis, caused by bacteria infecting gill epithelial cells in fish, is common among a large range of fish species in both fresh-and seawater. The aquaculture industry considers epitheliocystis an important problem. It affects the welfare of the fish and the resulting gill disease may lead to mortalities. In a culture facility in Kampala, Uganda, juveniles of the African sharptooth catfish (Clarias gariepinus) was observed swimming in the surface, sometimes belly up, showing signs of respiratory problems. Histological examination of gill tissues from this fish revealed large amounts of epitheliocysts, and also presence of a few Ichthyobodo sp. and Trichodina sp. Methods and Results: Sequencing of the epitheliocystis bacterium 16S rRNA gene shows 86.3% similarity with Candidatus Piscichlamydia salmonis causing epitheliocystis in Atlantic salmon (Salmo salar). Transmission electron microscopy showed that the morphology of the developmental stages of the bacterium is similar to that of members of the family Chlamydiaceae. The similarity of the bacterium rRNA gene sequences compared with other chlamydia-like bacteria ranged between 80.5% and 86.3%. Inclusions containing this new bacterium have tubules/channels (termed actinae) that are radiating from the inclusion membrane and opening on the cell surface or in neighbouring cells. Conclusions: Radiation of tubules/channels (actinae) from the inclusion membrane has never been described in any of the other members of Chlamydiales. It seems to be a completely new character and an apomorphy. We propose the name Candidatus Actinochlamydia clariae gen. nov., sp. nov. (Actinochlamydiaceae fam. nov., order Chlamydiales, phylum Chlamydiae) for this new agent causing epitheliocystis in African sharptooth catfish

Genes related to cell-mediated cytotoxicity and interferon response are induced in the retina of European sea bass upon intravitreal infection with nodavirus

Viral diseases are responsible for high rates of mortality and subsequent economic losses in modern aquaculture. The nervous necrosis virus (NNV) produces viral encephalopathy and retinopathy (VER), which affects the central nervous system, is considered one of the most serious viral diseases in marine aquaculture. Although some studies have localized NNV in the retina cells, none has dealt with immunity in the retina. Thus, for the first time, we intravitreally infected healthy specimens of European sea bass (Dicentrarchus labrax) with NNV with the aim of characterizing the immune response in the retina. Ultrastructural analysis detected important retinal injuries and structure degradation, including pycnosis, hydropic degeneration and vacuolization in some cell layers as well as myelin sheaths in the optic nerve fibres. Immunohistochemistry demonstrated that NNV re- plicated in the eyes. Regarding retinal immunity, NNV infection elicited the transcription of genes encoding proteins involved in the interferon (IFN) and cell-mediated cytotoxicity (CMC) responses as well as B and T cell markers, demonstrating that viral replication influences innate and adaptive responses. Further studies are needed to understand the retina immunity and whether the main retinal function, vision, is affected by noda- virus.Versión del edito

PENINGKATAN KEMAMPUAN REPRESENTASI DAN DISPOSISI MATEMATIS SISWA SEKOLAH MENENGAH PERTAMA DENGAN PENDEKATAN COLLABORATIVE PROBLEM SOLVING

Penelitian ini dilatarbelakangi oleh urgensi terhadap pentingnya kemampuan representasi dan disposisi matematis serta belum optimalnya hasil yang dicapai siswa terhadap kedua hal tersebut. Kajian dalam penelitian ini adalah tentang pencapaian dan peningkatan kemampuan representasi matematis, baik ditinjau secara keseluruhan maupun dari kategori kemampuan awal matematis (KAM) siswa (tinggi, sedang, rendah), mengkaji efisiensi belajar, serta pencapaian disposisi matematis siswa antara siswa yang memperoleh pembelajaran dengan pendekatan Collaborative Problem Solving (CoPS) dan siswa yang memperoleh pembelajaran biasa (PB). Penelitian ini merupakan penelitian kuasi eksperimen dengan desain non-equivalent pretest and posttest control group design. Populasi pada penelitian ini adalah siswa kelas VIII salah satu SMP di kota Padang. Sampel yang digunakan adalah dua kelas dari sembilan kelas yang ada. Instrumen pengumpulan data berupa instrumen tes kemampuan representasi matematis, skala disposisi matematis, skala usaha mental, dan lembar observasi. Pengujian hipotesis dilakukan dengan uji-t dan uji non parametrik Mann-Whitney U. Hasil penelitian menunjukkan bahwa: secara keseluruhan, pencapaian dan peningkatan kemampuan representasi matematis siswa yang memperoleh pembelajaran dengan pendekatan CoPS lebih baik daripada siswa yang memperoleh pembelajaran biasa; ditinjau dari KAM, pencapaian dan peningkatan kemampuan representasi matematis siswa kategori KAM sedang dan rendah yang memperoleh pembelajaran CoPS lebih baik daripada siswa yang memperoleh pembelajaran biasa, sedangkan kemampuan representasi matematis siswa kategori KAM tinggi yang memperoleh pembelajaran CoPS tidak lebih baik daripada siswa yang memperoleh pembelajaran biasa; tidak terdapat perbedaan efisiensi pendekatan CoPS dengan pembelajaran biasa terhadap kemampuan representasi matematis; dan pencapaian disposisi matematis siswa yang memperoleh pembelajaran dengan pendekatan CoPS lebih baik dibandingkan pembelajaran biasa. ; This research is motivated by the urgency of mathematical representation ability and mathematical dispositions’ importance as well as non-optimal results that achieved by students against both of that. This research reviews about achievement and enhancement of mathematical representation ability and mathematical disposition between students who obtain learning with Collaborative Problem Solving approach and students who obtain conventional learning, in terms of overall and category of early mathematical ability (EMA) of students (high, medium, low), then review learning efficiency, and achievement of mathematical disposition. This research is quasi experimental with non-equivalent pretest and posttest control group design. The population is eighth-grade students from one of junior high school in Padang. The samples used were two classes of nine existing classes. The research instrument were mathematical representation ability test, mathematical disposition scale, mental effort scale, and observation sheets. Hypothesis testing using t-test and non parametric Mann-Whitney U test. The results showed that: overall, both of achievement and enhancement about mathematical representation ability of students who obtain CoPS learning better than students who obtain conventional learning; in terms of EMA, achievement and enhancement students’ mathematical representation ability from medium and low EMA categories who obtain CoPS learning better than students who obtain conventional learning, whereas at high EMA students who obtain CoPS learning are not better than student who obtain conventional learning; from mathematical representation ability point of view, CoPS learning efficiency is not different from conventional learning efficiency; and achievement of students’ mathematical disposition who obtain CoPS is better than students who obtain conventional learning

Amoebic gill disease due to Paramoeba perurans in ballan wrasse (Labrus bergylta)

Ballan wrasse (Labrus bergylta) is cultured for the use as cleaner fish in Atlantic salmon farms. A low level of mortality was experienced in ballan wrasse broodstock tanks during spawning. Examined moribund and clinically healthy fish showed patchy gill lesions characteristic of amoebic gill disease (AGD). Microscopy on wet preparations from gill patches showed large numbers of amoebae. Histology revealed pathology characteristic for AGD, such as extensive hyperplasia, bridging of lamellae and forming of interlamellar spaces. Lesions were associated with amoebae, resembling Paramoeba spp. Molecular studies on both gill samples and gill-derived amoeba-cultures showed the presence of Paramoeba perurans. These observations show that cultured ballan wrasse may host P. perurans infections. Since this observation suggests that ballan wrasse may be infected with P. perurans also in nature, the possible role of wrasses in the epizootiology of AGD in salmonid aquaculture needs to be examined

Paraffin sections from gill tissues.

<p>The sections of gill tissue from <i>Clarias gariepinus</i> have been processed for <i>in situ</i> hybridization or stained with HES. A) Primary filament showing dark-blue stained <i>Candidatus</i> Actinochlamydia clariae inclusions, stained with antisense DIG-labelled RNA-probe against <i>Ca.</i> A. clariae 16S rRNA. Cells with inclusions are particularly frequent at the filament tip. Bar = 100.0 µm. B) Same primary filament stained with a sense probe, demonstrating absence of staining in the inclusions (examples indicated by arrows). Bar = 100.0 µm. C) HES stained section of the same filament tip. Bar = 100.0 µm. D) Magnification of an IHC stained inclusion, where the actiniae are discernible (arrowhead). Bar 10.0 = µm.</p

Semi-thin sections of infected primary lamellas from African sharptooth catfish.

<p>Pictures of semi-thin sections of the primary gill lamellas from African sharptooth catfish infected with <i>Candidatus</i> Actinochlamydia clariae. Arrows point to cysts of variable sizes. The majority of the cysts are located towards the apical part of the primary lamellas. A) Bar = 60.0 µm. B) Bar = 30.0 µm.</p

Phylogenetic tree.

<p>The phylogenetic tree shows the relationship between <i>Candidatus</i> Actinochlamydia clariae from African sharptooth catfish and selected members of other families within the order Chlamydiales. The best-fitting nucleotide substitution model was used during maximum likelihood analysis and the tree was bootstrapped (50 000 quartet puzzling steps) in TREE_PUZZLE. The scale bar shows the number of nucleotide substitutions as a proportion of branch lengths.</p

Nucleotide similarity of <i>Ca</i>. Actinochlamydia clariae (Accession nos: JQ480299, JQ480300, JQ480301) compared to other members of the order Chlamydiales.

<p>Nucleotide similarity of <i>Ca</i>. Actinochlamydia clariae (Accession nos: JQ480299, JQ480300, JQ480301) compared to other members of the order Chlamydiales.</p

Section through inclusion with EBs.

<p>Section through a large inclusion from the gills of <i>Clarias gariepinus</i> containing mainly EBs. A) The cyst is beginning to open to the gill surface (arrow), and the host cell cytosol shows signs of degeneration. A neighbouring cell contains an inclusion with RBs only (asterisk). Bar = 5.0 µm. B) Section through EB showing the cap area with associated protein structures (arrow). Tangential section through the cap area (ring) showing the hexagonal arrangement of the proteins. Bar = 0.2 µm. C) Section through free EBs showing the smooth cap areas (arrows) with proteins, an electron dense core (nucleoid), and condensed cytoplasm consisting mainly of ribosomes. Bar = 0.2 µm.</p

Cysts of <i>Candidatus</i> Actinochlamydia clariae.

<p>High magnification pictures of cysts containing <i>Ca</i>. A. clariae. Figures A) and B) show medium size cysts with tubules/channels radiating from the inclusion giving the cysts its distinct morphology. A) and B) Bars = 30.0 µm. B) A tangential section of the cyst clearly shows that the projections are tubules/channels (ring). C) This figure shows a large cyst, about 30 µm in diameter, containing mostly EBs (asterisk). C) Bar = 30.0 µm.</p