Altered neuronal activity in the visual processing region of eye-fluke-infected fish

Fish, like most vertebrates, are dependent on vision to varying degrees for a variety of behaviours such as predator avoidance and foraging. Disruption of this key sensory system therefore should have some impact on the ability of fish to execute these tasks. Eye-flukes, such as Tylodelphys darbyi, often infect fish where they are known to inflict varying degrees of visual impairment. In New Zealand, T. darbyi infects the eyes of Gobiomorphus cotidianus, a freshwater fish, where it resides in the vitreous chamber between the lens and retina. Here, we investigate whether the presence of the parasite in the eye has an impact on neuronal information transfer using the c-Fos gene as a proxy for neuron activation. We hypothesized that the parasite would reduce visual information entering the eye and therefore result in lower c-Fos expression. Interestingly, however, c-Fos expression increased with T. darbyi intensity when fish were exposed to flashes of light. Our results suggest a mechanism for parasite-induced visual disruption when no obvious pathology is caused by infection. The more T. darbyi present the more visual stimuli the fish is presented with, and as such may experience difficulties in distinguishing various features of its external environment.

[Facial trauma and multiple trauma]

The human face contains the sense organs and is responsible for essential functions: swallowing, chewing, speech, breathing and communication. It is also and most importantly the seat of a person's identity. Multiple trauma adds a life-threatening dimension to the physical and psychological impact of a facial trauma.

[Poorly healing periorbital wounds. Therapeutic use of maggots]

The treatment of poorly healing wounds, although not a typical problem in the periorbital area, has been enriched by the option of biosurgery, the therapeutic application of larvae of the blow fly (Lucilia sericata).

Binding of Acanthamoeba to [corrected] mannose-glycoproteins of corneal epithelium: effect of injury

PURPOSE

Acanthamoeba keratitis is a sight-threatening corneal infection. It is known that: (i) more amoebae bind to the surface of injured corneas than to the normal corneal surface and (ii) mannose-containing glycoproteins (GPs) possess binding sites for Acanthamoeba. The present study was undertaken to determine whether subtle corneal surface injury exposes mannose-GPs and whether more amoebae bind to the mannose-GPs of injured corneas than to those of normal corneas.

METHODS

Corneal cup assays were developed to determine whether corneal surface injury exposes binding sites for a mannose/glucose-specific lectin, succinylated-concanavalin A (s-ConA). To determine whether injury exposes mannose-GPs, corneal surface proteins were biotinylated, biotin-labeled mannose-GPs were allowed to bind to s-ConA-agarose beads and were analyzed by SDS-polyacrylamide gel electrophoresis (PAGE). Amoeba binding to mannose-GPs of corneal epithelia was analyzed by PAGE-blot overlay assays.

RESULTS

S-ConA binding site density was 2.4 times greater on the injured corneal surface than on the surface of normal corneas. Based on the analysis of the s-ConA-bound, biotin-labeled corneal surface proteins, approximately 5.2 times greater amounts of mannose-GPs were present on the surface of injured corneas than on the normal corneal surface. PAGE-blot overlay assays of s-ConA bound GPs of unlabeled corneal epithelia revealed that, on a per mg total cell protein basis, injured corneal epithelium contained 1.8 times greater amounts of Acanthamoeba-reactive mannose-GPs than normal corneal epithelium.

CONCLUSIONS

Subtle corneal injury exposes mannose-GPs on the surface of injured corneas. The newly exposed GPs may serve to provide additional attachment sites for the amoebae. This, in turn, could render the cornea susceptible to the infection.