Salamanders have been habitual residents of research laboratories for more than a century, and their history in science is tightly interwoven with vision research. Nevertheless, many vision scientists – even those working with salamanders – may be unaware of how much our knowledge about vision, and particularly the retina, has been shaped by studying salamanders. In this review, we take a tour through the salamander history in vision science, highlighting the main contributions of salamanders to our understanding of the vertebrate retina. We further point out specificities of the salamander visual system and discuss the perspectives of this animal system for future vision research.

Bifenthrin (BF) is a new highly effective broad-spectrum insecticide that has gained widespread use. However, there is limited research on the potential toxic effects of bifenthrin pollution on amphibians. In this research, Chinese giant salamanders (CGS) were exposed to three different concentrations of BF (0, 0.04, and 4 g/L BF) for 1-week to investigate the toxic effects. Behavioral changes, liver pathology, oxidative stress factors, DNA damage, and transcriptome differences were observed and analyzed. The results showed that exposure to BF (0.04 and 4) significantly decreased the adenosine-triphosphate (ATP), superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), and 8-hydroxydeoxyguanosine (8-OHdG) contents in the brain, liver, and kidney of CGS, whereas the malondialdehyde (MDA) and reactive oxygen species (ROS) contents were increased. The liver tissue showed considerable inflammatory reactions and structural malformations. RNAseq analysis of the liver showed that BF caused abnormal antioxidant indices of CGS, which affected molecular function genes such as catalytic activity, ATP-dependent activity, metabolic processes, signaling and immune system processes, behavior and detoxification significantly up-regulated, resulting the differential genes were significantly enriched in calcium signaling pathway, PPARα signaling pathway and NF-kB signaling pathway. These results indicated that BF induced the abnormal production of free radicals to exceed the potential of the self-defense system, causing different degrees of oxidative damage and lipid peroxidation in the body, resulting in oxidative stress, abnormal lipid metabolism, DNA damage, tissue inflammation, and abnormal behavior. This work provides a theoretical basis for the rational use of pyrethrin and environmental risks assessment, and scientific guidance for the conservation of amphibian populations.

Diabetes is a group of diseases characterized by loss of β cell mass and/or -function, resulting in hyperglycemia. Approx. 537 million people worldwide suffer from diabetes – a number which is expected to increase. Diabetes is primarily treated by exogenous insulin, which comes with the challenges of maintaining glycemic control to prevent ketoacidosis and severe complications. The need for a curative treatment has initiated the research in β cell regeneration. Several studies in mice have identified essential genes for β cell fate, which can be manipulated in other cells to induce generation of new β cells. Zebrafish, a regeneration-positive animal model, has shown several different sources of new β cells, including regeneration by self-replication, neogenesis by duct-associated progenitor cells, and transdifferentiation of other endocrine islet cells. The animal models used in this research area are either limited by their low regenerative ability (mice), or their small size and remoteness from humans (zebrafish). There is a need for new animal models of diabetes, in which the molecular pathways of endogenous regeneration can be studied. This study proposes the axolotl salamander (Ambystoma mexicanum) as a model for studying the regeneration of β cells. The axolotl has shown great regenerative capability, as they have proven capable of regenerating amputated limbs, and hearts with myocardial infarction, among other organs. This study aims to establish a diabetic axolotl model, investigate their regenerative ability in the pancreas, and examine the potential systemic effects of the induced disease. In a pilot study, five different protocols using STZ (streptozotocin) were tested, and the most optimal protocol was found. Furthermore, the glucose tolerance test was optimized to characterize the glycemic state of the animals. The effect of the treatment on blood glucose levels was measured to characterize the development and decline of the disease. The histological changes in the pancreas were examined. Moreover, the systemic effects of the STZ treatment were investigated in blood and urine. The study indicated that it is possible to induce diabetes in the axolotl, but variations between the animals should be minimized, or the sample size should be increased to conduct a satisfying experiment, as it was not possible to induce diabetes in all animals. Regeneration was not observed histologically, but a restoration of blood glucose levels was seen over the span of the experiment. Lastly, edema formation was observed in some of the STZ-treated animals, but the cause of edema remains undetermined.