Investigation of the peak action wavelength of light-activated gene transduction

Effects of ultraviolet radiation to Solea senegalensis during early development

Ultraviolet radiation (UVR) reaching the Earth surface is increasing and scarce information is available regarding effects of this stressor to early life stages of marine vertebrates. Therefore, this work aims to study the effects of UVR exposure during early development stages of the flatfish Solea senegalensis. Firstly, fish were exposed to UVR (six daily doses between 3.4 ± 0.08 and 8.6 ± 0.14 kJ m^-2) at the following moments: gastrula stage (24 h post fertilization, hpf), 1 and 2 days after hatching (dah, 48 and 72 hpf, respectively). In a second bioassay, fish at the beginning of metamorphosis were exposed to UVR (one or two daily doses of 7.2 ± 0.39 or 11.1 ± 0.49 kJ m^-2) and then maintained until the end of metamorphosis. Mortality and effects on development, growth and behaviour were evaluated at the end of both bioassays (3 dah and 18 dah, respectively). Biomarkers of neurotransmission (acetylcholinesterase, AChE), oxidative stress (catalase, CAT) and biotransformation (glutathione S-transferase, GST) were also determined at the end of the early larvae bioassay, and metamorphosis progression was evaluated during the second bioassay. UVR exposure caused distinct effects depending on life stage. Altered pigmentation, decreased growth, impaired fish behaviour and AChE and GST inhibition were observed at the earlier larval phase. Whereas, decrease in growth was the main effect observed at the metamorphosis stage. In summary, the exposure of S. senegalensis early stages to environmentally relevant UVR doses led to adverse responses at different levels of biological organization, which might lead to implications in later life stages.

Cell death in human articular chondrocyte: a morpho-functional study in micromass model

Chondrocyte death and loss of extracellular matrix are the central features in articular cartilage degeneration during osteoarthritis pathogenesis. Cartilage diseases and, in particular, osteoarthritis are widely correlated to apoptosis but, chondrocytes undergoing apoptosis "in vivo" more often display peculiar features that correspond to a distinct process of programmed cell death termed "chondroptosis". Programmed cell death of primary human chondrocyte has been here investigated in micromasses, a tridimensional culture model, that represents a convenient means for studying chondrocyte biology. Cell death has been induced by different physical or chemical apoptotic agents, such as UVB radiation, hyperthermia and staurosporine delivered at both 1 and 3 weeks maturation. Conventional electron microscopy was used to analyse morphological changes. Occurrence of DNA fragmentation and caspase involvement were also investigated. At Transmission Electron Microscopy, control cells appear rounding or slightly elongated with plurilobated nucleus and diffusely dispersed chromatin. Typically UVB radiation and staurosporine induce chromatin apoptotic features, while hyperthermia triggers the "chondroptotic" phenotype. A weak TUNEL positivity appears in control, correlated to the well known cell death patterns occurring along cartilage differentiation. UVB radiation produces a strong positivity, mostly localized at the micromass periphery. After hyperthermia a higher number of fluorescent nuclei appears, in particular at 3 weeks. Staurosporine evidences a diffuse, but reduced, positivity. Therefore, DNA fragmentation is a common pattern in dying chondrocytes, both in apoptotic and "chondroptotic" cells. Moreover, all triggers induce caspase pathway activation, even if to a different extent, suggesting a fundamental role of apoptotic features, in chondrocyte cell death.