BackgroundKillerRed (KR) is a novel photosensitizer that efficiently generates reactive oxygen species (ROS) in KR-expressing cells upon intense green or white light illumination in vitro, resulting in damage to their plasma membrane and cell death.ResultsWe report an in vivo modification of this technique using a fluorescent microscope and membrane-tagged KR (mem-KR)-expressing transgenic zebrafish. We generated several stable zebrafish Tol2 transposon-mediated enhancer-trap (ET) transgenic lines expressing mem-KR (SqKR series), and mapped the transposon insertion sites. As mem-KR accumulates on the cell membrane and/or Golgi, it highlights cell bodies and extensions, and reveals details of cellular morphology. The photodynamic property of KR made it possible to damage cells expressing this protein in a dose-dependent manner. As a proof-of-principle, two zebrafish transgenic lines were used to affect cell viability and function: SqKR2 expresses mem-KR in the hindbrain rhombomeres 3 and 5, and elsewhere; SqKR15 expresses mem-KR in the heart and elsewhere. Photobleaching of KR by intense light in the heart of SqKR15 embryos at lower levels caused a reduction in pumping efficiency of the heart and pericardial edema and at higher levels - in cell death in the hindbrain of SqKR2 and in the heart of SqKR15 embryos.ConclusionsAn intense illumination of tissues expressing mem-KR affects cell viability and function in living zebrafish embryos. Hence, the zebrafish transgenics expressing mem-KR in a tissue-specific manner are useful tools for studying the biological effects of ROS.

Objective: To evaluate the use of the Leipzig distractor during canine shoulder arthroscopy. Study design: Experimental, ex vivo. Sample population: Paired shoulder joints from 15 large breed canine cadavers. Methods: Standard lateral shoulder arthroscopy was performed with or without the use of the Leipzig distractor (n = 15 each). Joint space width, procedure time, and visibility and palpability of the intra-articular structures were assessed during the arthroscopy. After the arthroscopic evaluation, each shoulder joint was disarticulated to assess the area and number of iatrogenic articular cartilage injury (IACI) lesions. Sites around the distraction device were assessed for the presence of iatrogenic injury. Results: With shoulder distraction, median joint space width was 4 mm larger (P = .01), IACI area was 9.5 mm 2 lower (P = .003), and there were two fewer total number of IACI lesions (P = .004) compared with nondistracted shoulders. The mean total surgery time was 93 seconds shorter (P = .01) in distracted shoulders. Although distraction was associated with increased visibility of the supraglenoid tubercle (P = .015), no significant differences were found for other intra-articular structures for their visibility and palpability. Unexpected lesions at the sites around the distraction device were not encountered. Conclusion: Use of the distraction device decreased the area and incidence of IACI lesions and shortened the arthroscopy time. However, no improvement was found in the visibility or palpability of the intra-articular structures. Clinical significance: Although additional clinical studies are required to evaluate the effect of the distraction device on pathologic articular conditions and intraoperative manipulation, the use of a shoulder distraction device might improve the outcomes of shoulder arthroscopy by decreasing IACI and arthroscopy time.

limbs/fins, thereby stimulating and maintaining the proliferation of blastemal cells and up-regulating genes important for an effective regeneration progress. Some candidate molecules have been suggested to play the role of MGFs, however, the cellular and molecular mechanisms involved in the dependence of innervation during regeneration are still largely unknown, due to limitations to molecular and genetic manipulation in the organisms previously studied.To clarify the role of the nerve fibres in the process of regeneration we are using the adult zebrafish fin as a model system. We have chosen the zebrafish because this organism has several experimental advantages, including amenability to molecular and genetic manipulation. We have surgically denervated the pectoral fin before its amputation and our results confirm the necessity of proper innervation for fin regeneration to occur. This procedure will allow us to describe in more detail the dynamics of nerve dependence and investigate the role of putative MGFs and its targets, by studying their expression and function, using the molecular tools available in zebrafish.Photosensitizers are chromophores that generate reactive oxygen species (ROS) upon light irradiation. Prolonged illumination of photosensitizer-expressing cells results in localized tissue damage caused by accumulation of reactive oxygen species. The aim of this study is to generate a set of transgenics with tissuespecific expression of a novel photosensitizer, KillerRed (KR) and to elicit precise killing in a temporally and spatially controlled manner in the optically translucent zebrafish embryos.For that an enhancer trap screen for tissue-specific expression of membrane-tethered KR was done using Tol2 transposon-mediated transgenesis. KR is a genetically encoded photosensitizer derived from hydrozoan chromoprotein anm2Cp. KR is capable of producing both singlet oxygen and superoxide upon irradiation with green light. Twenty transgenic lines with tissue-specific KR expression were generated. We present our preliminary results of spatially and temporally controlled killing of KR-positive cells in one of these transgenic lines and demonstrate for the first time KR-specific phototoxic effect in living transgenic zebrafish embryos. We are confidant that these KR transgenic lines expressing the red fluorescent protein with inducible phototoxic properties will become useful tools for both developmental biology and regeneration studies. Axolotls (urodele amphibians) have the unique ability, among vertebrates, to perfectly regenerate many parts of their body following injury or amputation. The axolotl limb is the most widely studied structure as an experimental model for tissue regeneration. When amputated, the missing or wounded part is regenerated perfectly without scar formation between the stump and the regenerated structure. On the opposite, mammals heal by fibrosis and one very important family of growth factors implicated in the control of almost all aspects of wound healing is the TGF-b family. ...