Moderate pathogenic effect of Ligophorus uruguayense (Monogenoidea, Ancyrocephalidae) in juvenile mullet Mugil liza (Actinopterygii, Mugilidae) from Brazil

ABSTRACT Monogenoidea pathogenic activity can elicit various histological responses in fish. Species of Ligophorus are specific parasites of mullets, and its relationship with host fish may result in a moderate pathogenic action. In order to ascertain this relationship, estuarine mullets (Mugil liza) were collected in an estuary, reared in laboratory, for three weeks, and forwarded for histological and parasitological analyses. Ligophorus uruguayense (Monogenoidea) infestation in the gills of the mullets was identified. The severe infestation by only one species of Monogenoidea may result from the specificity of these parasites to mullets. Mullets submitted to histological analysis exhibited respiratory epithelium detachment; mild, moderate and severe hyperplasia of the respiratory epithelium; atrophy; and telangiectasia of the gills. This is the first study reporting that mullets highly infested by Monogenoidea can show mild (100%) to severe (20%) gill changes with a distinct frequency of occurrence. Because of the high prevalence of mild alterations observed, it is possible to accept that L. uruguayense is moderately pathogenic to M. liza, even during high prevalence and intensity of infestation, as a result of its specificity

Biopersistence of PEGylated Carbon Nanotubes Promotes a Delayed Antioxidant Response after Infusion into the Rat Hippocampus.

Carbon nanotubes are promising nanomaterials for the diagnosis and treatment of brain disorders. However, the ability of these nanomaterials to cross cell membranes and interact with neural cells brings the need for the assessment of their potential adverse effects on the nervous system. This study aimed to investigate the biopersistence of single-walled carbon nanotubes functionalized with polyethylene glycol (SWCNT-PEG) directly infused into the rat hippocampus. Contextual fear conditioning, Y-maze and open field tasks were performed to evaluate the effects of SWCNT-PEG on memory and locomotor activity. The effects of SWCNT-PEG on oxidative stress and morphology of the hippocampus were assessed 1 and 7 days after infusion of the dispersions at 0.5, 1.0 and 2.1 mg/mL. Raman analysis of the hippocampal homogenates indicates the biopersistence of SWCNT-PEG in the hippocampus 7 days post-injection. The infusion of the dispersions had no effect on the acquisition or persistence of the contextual fear memory; likewise, the spatial recognition memory and locomotor activity were not affected by SWCNT-PEG. Histological examination revealed no remarkable morphological alterations after nanomaterial exposure. One day after the infusion, SWCNT-PEG dispersions at 0.5 and 1.0 mg/mL were able to decrease total antioxidant capacity without modifying the levels of reactive oxygen species or lipid hydroperoxides in the hippocampus. Moreover, SWCNT-PEG dispersions at all concentrations induced antioxidant defenses and reduced reactive oxygen species production in the hippocampus at 7 days post-injection. In this work, we found a time-dependent change in antioxidant defenses after the exposure to SWCNT-PEG. We hypothesized that the persistence of the nanomaterial in the tissue can induce an antioxidant response that might have provided resistance to an initial insult. Such antioxidant delayed response may constitute an adaptive response to the biopersistence of SWCNT-PEG in the hippocampus

Levels of reactive oxygen species (ROS) in the hippocampus (A) 1 and (B) 7 days after theinfusion of SWCNT-PEG dispersions.

<p>Values are expressed as the mean ± SEM, n = 4–6. *<i>p</i> <0.05 vs. control group.</p

Raman spectroscopy of rat hippocampal homogenates 1 and 7 days after SWCNT-PEG dispersions infusion.

<p>(A) Raman spectrum acquired from SWCNT-PEG dispersion at 2.1 mg/mL. (B) Detection curve of SWCNT-PEG based on radial breath mode (RBM). Raman spectra in hippocampal homogenates (C) 1 and (D) 7 days after infusion. Dotted squares indicate the RBM region. Ct+: positive control; Ct-: negative control.</p

Effect of SWCNT-PEG on the number of crossings in open field task.

<p>Values expressed as the mean ± SEM (n = 6). Animals tested at 30 min were subjected to another test-session at 1 day. No significant differences were observed between the groups (<i>p</i>>0.05).</p><p>Effect of SWCNT-PEG on the number of crossings in open field task.</p

Effect of SWCNT-PEG dispersions on spontaneous alternation behavior (A) 1 and (B) 7 days after infusion.

<p>Schematics of the procedures used in the experiments are presented above the graphs. Values are expressed as the mean ± SEM, n = 6. No significant difference in percentage of alternation was observed between the groups (<i>p</i>>0.05).</p

Effect of SWCNT-PEG dispersions on total antioxidant capacity against peroxyl radicals (ACAP) in the hippocampus (A) 1 and (B) 7 days after infusion.

<p>Values are expressed as the mean ± SEM, n = 4–6. ^#<i>p</i><0.05 vs. 2.1 mg/mL SWCNT-PEG and vs. the control group; *<i>p</i> <0.05 vs. the control group.</p

Fluorescence-based <i>in vitro</i> assays.

<p>Values are expressed as the mean ± SEM (n = 4). No significant differences were registered for the different SWCNT-PEG concentrations (<i>p</i>>0.05).</p><p>Fluorescence-based <i>in vitro</i> assays.</p

Effect of SWCNT-PEG dispersions on lipid peroxidation (LPO) in the hippocampus (A) 1 and (B) 7 days after infusion.

<p>Values are expressed as the mean ± SEM, n = 4–6. No significant difference in LPO levels was observed between the groups (<i>p</i>>0.05).</p