Insights regarding skin regeneration in non-amniote vertebrates: Skin regeneration without scar formation and potential step-up to a higher level of regeneration.

Skin wounds are among the most common injuries in animals and humans. Vertebrate skin is composed of an epidermis and dermis. After a deep skin injury in mammals, the wound heals, but the dermis cannot regenerate. Instead, collagenous scar tissue forms to fill the gap in the dermis, but the scar does not function like the dermis and often causes disfiguration. In contrast, in non-amniote vertebrates, including fish and amphibians, the dermis and skin derivatives are regenerated after a deep skin injury, without a recognizable scar remaining. Furthermore, skin regeneration can be compared with a higher level of organ regeneration represented by limb regeneration in these non-amniotes, as fish, anuran amphibians (frogs and toads), and urodele amphibians (newts and salamanders) have a high capacity for organ regeneration. Comparative studies of skin regeneration together with limb or other organ regeneration could reveal how skin regeneration is stepped up to a higher level of regeneration. The long history of regenerative biology research has revealed that fish, anurans, and urodeles have their own strengths as models for regeneration studies, and excellent model organisms of these non-amniote vertebrates that are suitable for molecular genetic studies are now available. Here, we summarize the advantages of fish, anurans, and urodeles for skin regeneration studies with special reference to three model organisms: zebrafish (Danio rerio), African clawed frog (Xenopus laevis), and Iberian ribbed newt (Pleurodele waltl). All three of these animals quickly cover skin wounds with the epidermis (wound epidermis formation) and regenerate the dermis and skin derivatives as adults. The availability of whole genome sequences, transgenesis, and genome editing with these models enables cell lineage tracing and the use of human disease models in skin regeneration phenomena, for example. Zebrafish present particular advantages in genetics research (e.g., human disease model and Cre-loxP system). Amphibians (X. laevis and P. waltl) have a skin structure (keratinized epidermis) common with humans, and skin regeneration in these animals can be stepped up to limb regeneration, a higher level of regeneration.

Publication Productivity in Central Asia and Countries of the Former Soviet Union.

INTRODUCTION: Despite the significant number of research institutions and rich scientific heritage, published research from Central Asia (Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan, and Turkmenistan) is traditionally underrepresented in international scientific literature. The goal of this paper was to analyze publication patterns in Central Asian countries, and to explore the factors that contributed to the publication productivity in Kazakhstan. METHODS: Publication productivity was evaluated using data generated by the SCImago Journal & Country Rank over the period of 1996-2014 for all of the 15 former Soviet Union Republics for all subject categories. Country specific data, including total population, gross domestic product (GDP) per capita, research and development (R&D) expenditure (% of GDP), number of reserchers (per million people), was abstracted from World Bank data. ANOVA and ANCOVA analyses compared the mean number of publications among Central Asian countries. Separate analyses was done for publication patterns in the health sciences. Multiple comparisons were performed using Tukey method. RESULTS: The analysis of publication productivity showed significant discrepancies in the number of published documents among the Central Asian countries. Kazakhstan demonstrated a significant increase in the number of published documents in the period of 1996-2014, mainly in the areas of natural and multidisciplinary sciences. Our analyses also showed that the number of publications are siginicantly associated with GDP and population size. CONCLUSIONS: We identified large gaps in publication productivity among the Central Asian countries. The association between publication rate with GDP and population size indicates there is a need to adjust for these factors when planning research policy.