Sperm morphology and distribution of intramembranous particles in the sperm heads of selected freshwater teleosts

The morphology of spermatozoa and the distribution of intramembranous particles (IMPs) in sperm-head membranes in teleostean fish were examined ultrastructurally to clarify the presence of characteristic arrays (parallelogram or hexagon in packing) of IMPs. The following four species of fish were used: goldfish (Carassius auratus), loach (Misgurnus anguillicaudatus), flat bitterling (Acheilognatus rhombeus), sweetfish (Plecoglossus altivelis). It was demonstrated that spermatozoa of all these fish were devoid of an acrosomal structure in the anterior portion of the head. Spermatozoa had round heads in goldfish, loach and flat bitterling. Two centrioles (proximal centriole and basal body) were present and located adjacent to each other in all fish. The characteristic arrays of IMPs were found in spermatozoa of goldfish and flat bitterling. IMPs were more numerous on the P-face than on the E-face in all species. The present work showed that the characteristic arrays of IMPs were not common structures in spermatozoa of teleostean fish.     

High-throughput molecular identification of fish eggs using multiplex suspension bead arrays

The location and abundance of fish eggs provide information concerning the timing and location of spawning activities and can provide fishery-independent estimates of spawning biomass. However, the full value of egg and larval surveys is severely restricted because many species' eggs and larvae are morphologically similar, making species-level identification difficult. Recent efforts have shown that nearly all species of fish may be identified by mitochondrial DNA (mtDNA) sequences (e.g. via 'DNA barcoding'). By taking advantage of a DNA barcode database, we have developed oligonucleotide probes for 23 marine fish species that produce pelagic eggs commonly found in California waters. Probes were coupled to fluorescent microspheres to create a suspension bead array. Biotin-labelled primers were used to amplify the mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal rRNA genes from individual fish eggs. The amplicons were then hybridized to the bead array, and after the addition of a reporter fluorophore, samples were analysed by flow cytometry with Luminex 100 instrumentation. Probes specifically targeted eggs that are abundant and/or from morphologically indistinguishable species pairs. Results showed that the 33 different probes designed for this study accurately identified all samples when PCR was successful. Suspension bead arrays have a number of benefits over other methods of molecular identification; these arrays permit high multiplexing, simple addition of new probes, high throughput and lower cost than DNA sequencing. The increasing availability of DNA barcode data for numerous fish faunas worldwide suggests that bead arrays could be developed and widely used for fish egg, larval and tissue identifications.     

Ontogeny of the Alimentary Canal and Respiratory Physiology of Larval Hoplosternum littorale (Hancock, 1828): an Intestinal Air-Breathing Teleost

Synopsis Newly hatched larval Hoplosternum littorale do not exhibit bimodal respiration upon hatching but depend initially on branchial respiration. As the respiratory intestine develops, its increasing length leads to an increasing dependence on aerial respiration. The respiratory intestine first appears when the fish is 9 days old but is microscopic at this age and becomes detectable by gross morphological examination at 13 days old. Development of the gut for the remainder of the juvenile period (up to 32 days old) consists of increasing length, mucosal folding, concentration of taste buds, gastric glands, mucous glands and goblet cells. Stage 1 commenced with newly hatched larvae until the larval fish were 11 days old. During this stage the fish did not have the capacity to air-breathe and thus behaved as oxygen conformers. Stage 2 extended from day 12 to day 23 and the fish had the capacity to air-breathe although the respiratory intestine was still developing. Stage 3 began from day 24 to day 32 and at this point the respiratory intestine was well-developed and functioned efficiently. The rate of oxygen consumption of the larval fish was found to be related to dissolved oxygen concentration, age of the larval fish and various interactions of these two factors.     

The effects of parasitism by the plerocercoid of Schistocephalus solidus Muller 1776 (Pseudophyllidea) on the respiration of the three-spined stickleback Gasterosteus aculeatus L.

Rates of oxygen consumption by parasitized and unparasitized sticklebacks were recorded at three levels of activity in February and August. Negative correlations were demonstrated between specific respiratory rates and fish body weights. At routine and maximum activity, infected fish consumed more oxygen than uninfected fish. At minimum activity levels no significant differences in respiration rates were detected. Seasonal variation in respiration rates was attributed to acclimation. Difficulties of determining specific respiration rates for parasitized organisms are discussed and attempts are made to assess the physiological basis of the respiratory and behavioural characteristics of infected fish.     

Organization of 5S rDNA in species of the fish Leporinus: two different genomic locations are characterized by distinct nontranscribed spacers.

To address understanding the organization of the 5S rRNA multigene family in the fish genome, the nucleotide sequence and organization array of 5S rDNA were investigated in the genus Leporinus, a representative freshwater fish group of South American fauna. PCR, subgenomic library screening, genomic blotting, fluorescence in situ hybridization, and DNA sequencing were employed in this study. Two arrays of 5S rDNA were identified for all species investigated, one consisting of monomeric repeat units of around 200 bp and another one with monomers of 900 bp. These 5S rDNA arrays were characterized by distinct NTS sequences (designated NTS-I and NTS-II for the 200- and 900-bp monomers, respectively); however, their coding sequences were nearly identical. The 5S rRNA genes were clustered in two chromosome loci, a major one corresponding to the NTS-I sites and a minor one corresponding to the NTS-II sites. The NTS-I sequence was variable among Leporinus spp., whereas the NTS-II was conserved among them and even in the related genus Schizodon. The distinct 5S rDNA arrays might characterize two 5S rRNA gene subfamilies that have been evolving independently in the genome.     

Hydrokinetic Turbine Effects on Fish Swimming Behaviour

Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms^-1. The effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish movements, particularly for large species, with possible effects on habitat connectivity if migration routes are exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of several metres width to allow large fish to pass through. In combination with further research the insights from this study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological impacts.     

Interactions of Streptococcus iniae with phagocytic cell line

Streptococcus iniae has become one of the most serious aquatic pathogens in the last decade, causing large losses in wild and farmed fish worldwide. There is clear evidence that this pathogen is capable not only of causing serious disease in fish but also of being transferred to and infecting humans. In this study, we investigate the interaction of S. iniae with two murine macrophage cell lines, J774-A1 and RAW 264.7. Cytotoxicity assay demonstrated significant differences between live and UV-light killed IUSA-1 strains. The burst respiratory activity decreased to baseline after 1 and 4 h of exposure for J774-A1 and RAW 264.7, respectively. Immunofluorescent and ultrastructural study of infected cells confirmed the intracellular localization of bacteria at 1 h and 24 h post-infection. Using qRT-PCR arrays, we investigated the changes in the gene expression of immune relevant genes associated with macrophage activation. In this screening, we identified 11 of 84 genes up-regulated, we observed over-expression of pro-inflammatory response as IL-1α, IL-1β, and TNF-α, without a good anti-inflammatory response. Present findings suggest a capacity of S. iniae to modulate a mammalian macrophages cell lines to their survival and replication intracellular, which makes this cell type as a reservoir for continued infection.     

Respiratory pathogenesis of amoebic gill disease (AGD) in experimentally infected Atlantic salmon Salmo salar

The aim of this study was to investigate the respiratory responses of Atlantic salmon, Salmo salar, experimentally affected with amoebic gill disease (AGD). In Series I, arterial blood samples were taken over a 96 h period following amoebae addition to examine potential respiratory effects associated with initial exposure. No major significant treatment effects were found between fish exposed to amoebae and control (non-exposed) fish. Arterial pH (pHa) was seen to be significantly elevated at 48 h in AGD fish relative to the 0 h time point. To investigate the long-term respiratory effects associated with infection, fish were similarly exposed to amoebae and sampled over a 16 d period. As for Series I, caudal blood pH was significantly elevated by Day 2 (48 h) compared to the pre (Day 0)-time point, suggesting that initial exposure to amoebae and/or amoebae attachment may have induced an initial respiratory alkalosis via increased ventilation frequency and/or amplitude. From Day 7 onwards, and coinciding with a significant increase in the percentage of affected gill filaments, blood pH decreased significantly, possibly indicating the onset of the characteristic respiratory acidosis that has previously been described for experimentally AGD-affected Atlantic salmon. Although fish in this study showed up to 90% AGD-affected filaments, the corresponding respiratory results do not reflect a major acid-base disturbance. Therefore, the findings from the present study support the contention that, although AGD only affects the gill, AGD-associated mortality in Atlantic salmon may not be primarily associated with respiratory failure.     

In vitro effect of peas, Pisum pisum, and chickpeas, Cicer arietinum, on the immune system of gilthead seabream, Sparus aurata

The future for a sustainable aquaculture relies on the formulation of feed including alternatives to fish meal and fish oil that do not impair fish growth and that improve fish health status. Grain legumes such as field peas and chickpeas offer good sources of proteins, carbohydrates, fibers, vitamins, and minerals. The effect of peas and chickpeas on the immune system of seabream was assessed in vitro in order to detect any potential immunosuppressing problem. Peas was determined to be a better fishmeal alternative than chickpeas as they induced higher respiratory burst measured by the nitro blue tetrazolium assay and primed the Phorbol 12-myristate 13-acetate (PMA)-stimulated intracellular respiratory burst whereas chickpeas neither directly stimulated respiratory burst nor primed it. However, when the intra- and extracellular respiratory burst activities were taken into account, high concentrations of peas inhibited the zymosan- and PMA-triggered chemiluminescence. This apparent reduction of the production of reactive oxygen species may reflect in fact the antioxidant activity of legumes. This, together with the absence of effect on the phagocytosis activity, suggested that peas are not immunosuppressing gilthead seabream. Further in vivo studies preferably comporting a bacterial challenge will have to ascertain the absence of immunosuppressing effect of these legumes.     

水生动物和大鼠线粒体的呼吸链比较

用陆生哺乳动物线粒体呼吸链与水生动物线粒体呼吸链相比较的研究方法,探讨了呼吸链的功能与环境相适应的关系。研究了淡水中生活的草鱼肝丝线粒体,观察到琥珀酸脱氢酶的活性非常低,而ＮＡＤＨ脱氢酶和泛醌细胞色素Ｃ还原酶的活性较高。但海洋生物海绵的线粒体ＮＡＤＨ脱氢酶和琥垢酸脱氢酶的活性都非常低。     

Paracrystalline arrays in mitochondria following ageing of mitochondriain situ

Paracrystalline arrays of helical configuration were observed in the mitochondrial intracrystal spaces following prolonged ageing of mitochondriain situ. The occurrence of these mitochondria with the paracrystalline arrays, average diameter of about 70 Å, appeared to increase following an increase in the time of ageingin situ.The exact function of the mitochondria containing the paracrystalline arrays is unknown. These mitochondria could not possibly be responsible for the overall decline in the State 3 respiration, respiratory control index and the ADP/O ratio observed with intact mitochondria isolated after prolonged ageingin situ [21].     

Gill chloride cell proliferation and respiratory responses to hypoxia of the neotropical erythrinid fish Hoplias malabaricus

The effect of chloride cell proliferation on the respiratory function was evaluated by measuring oxygen consumption (VO2) and ventilatory parameters during normoxia and gradual hypoxia in the tropical fish Hoplias malabaricus. Chloride cell proliferation was induced by keeping fish in deionized water, and the effect on the respiratory function was measured on the 1st, 2nd, and 7th day in this water using a flow-through respirometry system. Plasma osmolarity and the partial pressure of arterial oxygen (PaO2) and carbon dioxide (PaCO2) were measured under conditions of normoxia and severe hypoxia. Chloride cell proliferation on the lamellae significantly increased the water-blood diffusion distance on the 2nd and 7th day in deionized water. VO2 was kept constant until the critical oxygen pressure (PcO2) of 21.6+/-0.9 mmHg in both the control and deionized water fish was reached. The ventilatory parameters were higher in deionized water fish in normoxia, and increased during hypoxia, matching decreases in the water's partial O2 pressure. Impairment of the respiratory function was evidenced by the decrease of PaO2 of deionized water fish in normoxic condition. However, despite the changes in the epithelial morphology of gills in fish kept in deionized water, H. malabaricus proved be a hypoxic-tolerant tropical species.     

Adaptations of fish species to oxygen depletion in a central Amazonian floodplain lake

Pronounced seasonal and daily oxygen concentration changes are characteristic for Amazonian floodplain lakes. Studies on the fish fauna of the Lago Camaleão, Solimões River, Amazonas, Brazil, showed several fish species which are able to survive prolonged periods of heavy hypoxia. Twenty species belonging to eight families were observed in the laboratory in order to determine their respiratory adaptations to hypoxic conditions and oxygen concentrations at which the fish present respiratory adaptations. Finally, the fish species were distributed throughout the habitats of Lake Camaleão according to their adaptation responses. Ten fish species used the surface water for aquatic surface respiration, four species used atmospheric oxygen for aerial respiration, four species used oxygen supplied by the exudation of the roots of floating macrophytes and two exhibited a high tolerance to hypoxic conditions, and well-developed physiological biochemical mechanisms. The fish fauna is well adapted to low oxygen concentrations. The large variety of morpho-anatomical adaptations associated with biochemical and physiological mechanisms to tolerate hypoxic and anoxic conditions enable the 20 fish species to exploit several habitats of Lago Camaleão, such as floating aquatic macrophyte meadows, open water and near the shoreline.     

Effects of graded hypoxia on Atlantic salmon infected with amoebic gill disease

Atlantic salmon Salmo salar with amoebic gill disease (AGD) were exposed to a graded hypoxia (135–40 mmHg water P O₂) and blood samples analysed for respiratory gases and pH at 119, 79·5 and 40 mmHg water P O₂. There were no differences in the rate of oxygen uptake between infected and control fish. However, arterial P O₂, and pH were significantly lower in the infected fish whereas P CO₂ was significantly higher in infected fish compared with controls prior to hypoxia and at 119 mmHg water P O₂. At 79·5 and 40 mmHg water P O₂ saturation, there were no significant differences in blood P O₂ or pH although blood P CO₂ was elevated in AGD affected fish at 50% hypoxia (79·5 mmHg water P O₂). The elevated levels of P CO₂ in fish affected by AGD resulted in a persistent respiratory acidosis even during hypoxic challenge. These data suggest that even though the fish were severely affected by AGD, the presence of AGD while impairing gas transfer under normoxic conditions, did not contribute to respiratory failure during hypoxia.     

Glycomic Analysis of Human Respiratory Tract Tissues and Correlation with Influenza Virus Infection

The first step in influenza infection of the human respiratory tract is binding of the virus to sialic (Sia) acid terminated receptors. The binding of different strains of virus for the receptor is determined by the α linkage of the sialic acid to galactose and the adjacent glycan structure. In this study the N- and O-glycan composition of the human lung, bronchus and nasopharynx was characterized by mass spectrometry. Analysis showed that there was a wide spectrum of both Sia α2-3 and α2-6 glycans in the lung and bronchus. This glycan structural data was then utilized in combination with binding data from 4 of the published glycan arrays to assess whether these current glycan arrays were able to predict replication of human, avian and swine viruses in human ex vivo respiratory tract tissues. The most comprehensive array from the Consortium for Functional Glycomics contained the greatest diversity of sialylated glycans, but was not predictive of productive replication in the bronchus and lung. Our findings indicate that more comprehensive but focused arrays need to be developed to investigate influenza virus binding in an assessment of newly emerging influenza viruses.     

Structural and morphological features of Piaractus mesopotamicus (Holmberg, 1887) gills

The pacu Piaractus mesopotamicus (Holmberg, 1887), is a commercially important serrasalmid fish endemic to the Paraná-Paraguay River basin, and one of the most widely cultivated native fish species in the Neotropics. As a migratory species, also inhabiting temporary pools subjected to hypoxic conditions, the species presents a high plasticity concerning respiratory adaptations. In order to supplement basic knowledge on the respiratory physiology and morphology of this species, some structural features of pacu gills, such as filament and lamellae structure, and circulatory pattern are described in this paper.     

Different sensitivity of carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss) to the immunomodulatory effects of UVB irradiation

In order to study the sensitivity of two fish species, carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss), to the immunomodulatory effects of ultraviolet B (UVB) radiation, the fish were exposed to a single UVB dose of 50, 250, 500 or 1,000 mJ cm(-2). These species represent different phylogenetic groups of fish, and they differ also in their behaviour inhabitating often dark and turbid (carp) or clear and transparent waters (salmonids). Immune responses were studied on day 1 post-irradiation. Unexposed fish, and fish exposed to radiation depleted of UV wavelengths served as controls. UVB irradiation markedly enhanced the blood respiratory burst and cytotoxic activity in carp, but in the head kidney these parameters were significantly suppressed. Rainbow trout respiratory burst was affected only after exposure with the highest dose of UVB. Lymphopenia and granulophilia were noted in both fish blood after exposure. This study indicates that UVB irradiation modulates immune functions in both fish species studied, and that rainbow trout is more tolerant than carp against UVB. Fish are clearly adapted to the environmental UVB levels prevailing in their usual living habitats, but are also a target of undesired effects of UVB on immune functions whenever exposed to increased radiation levels.     

Immune responses of great sturgeon Huso huso to Aeromonas hydrophila bacterin

The immunocompetent cell population, lysozyme activity, chemiluminescence response and antibody titre were assessed in great sturgeon Huso huso after intraperitoneal immunization with formalin-inactivated whole cells of Aeromonas hydrophila . Generally an increase was seen in indices of immunocomptent cell counts of immunized fish compared to the control group. The neutrophil count was higher in immunized fish from day 29. Lysozyme activity in liver and spleen samples of immunized fish was initially significantly higher than unimmunized fish, but was not different in serum and kidney. Antibody titre and respiratory burst in immunized fish were mainly significantly higher than unimmunized fish.