International Journal of Developmental Biology最新文献

The axial skeleton of the anurans has undergone an evolutionary reduction of its bone elements. This structural plan is strongly preserved throughout the order and would have emerged as a highly specialized anatomical adaptation to its locomotor jumping pattern. The development programs that direct the vertebral morphogenesis of the anurans are poorly described and the molecular bases that have caused their pattern to differ from other tetrapods are completely unknown. In this work, we review the ontogeny of the spinal column of the anurans and explore the genetic mechanisms that could explain the morphological difference and the maintenance of the body plan during evolution. Here, we propose that the absence of caudal osseous elements, as a consequence of the inability of sclerotomes to form cartilaginous condensations in frogs, could be due to changes in both pattern and expression levels of Hox, Pax1, Pax9 and Uncx4.1 genes along the anteroposterior axis. The anteriorised expression of the Hox genes together with the reduction in the expression levels of Pax1, Pax9 and Uncx4 in the posterior somites could explain, at least partly, the loss of caudal vertebrae in the anurans during evolution.

Roberto Mayor is a prominent Chilean developmental biologist working in the UK and an advocate of the developmental biology discipline in Latin America. Roberto started as a preimplantation mouse developmental biologist during his undergraduate and graduate studies in Chile. Yet, he now uses Xenopus and zebrafish to elucidate the mechanisms that drive the directed collective locomotion of neural crest cells. What life events moulded the research career of Roberto across the years? This article addresses this question and provides a personal perspective on his scientific achievements. The story of Roberto is a mix of turns and cycles that ultimately guided him to the migrating neural crest. Turns that made him shift between model organisms and scientific topics. Cycles that drove him back and forth between Chile and the UK and which have connected his early studies as an undergraduate student with the most recent work of his lab. A big lesson that we can learn from the life of Roberto is that no matter how much you plan your life always serendipity plays a significant role. But you have to be alert and brave to take the opportunities that life offers you.

Jorge E. Allende is a biochemist trained in the United States of America who has been a professor at the University of Chile since 1961. He has served in many leadership positions in both Chilean and international scientific organizations and academic institutions. He led the International Cell Research Organization, the Latin American Network of Biological Sciences and obtained the Chilean National Science Prize. He belongs to the Chilean Academy of Sciences and is a foreign member of the National Academy of Sciences (USA) and also of the National Academy of Medicine (USA). During his career, besides leading a highly successful research group, he was instrumental in generating an esprit de corps among Latin American scientists of all fields in biology starting in the late 1960's. He began a longstanding tradition by organizing advanced training courses for young scientists from the region who would not have otherwise had the opportunity to experience the latest methods and concepts in biological research, courses that had world leading researchers as instructors. A constant focus of his efforts consisted in promoting the establishment of postgraduate programs in biology throughout the continent, coordinating international funding programs aimed at scientific development in the third world and, more recently, advocating for science education among children and school teachers as the only way to achieve scientific literacy in our societies. In this interview, we explore how these issues were addressed by him and his counterparts in other Latin American countries, at a time when they had to start, essentially, from scratch.

Salamanders are the only vertebrates that can regenerate limbs as adults. This makes them ideal models to investigate the cellular and molecular mechanisms of tissue regeneration. Ambystoma mexicanum and Nothopthalmus viridescens have long served as primary salamander models of limb regeneration, and the recent sequencing of the axolotl genome now provides a blueprint to mine regeneration insights from other salamander species. In particular, there is a need to study South American plethodontid salamanders that present different patterns of limb development and regeneration. A broader sampling of species using next-generation sequencing approaches is needed to reveal shared and unique mechanisms of regeneration, and more generally, the evolutionary history of salamander limb regeneration.

In Uruguay, a country with a small population, and hence a small scientific community, there were no classical embryologists as such in the past. However, in the decade of the 1950s, a cumulus of favorable conditions gave rise to highly active and modern research groups in the fields of cytology and physiology, which eventually contributed to developmental biology. The advent of a long dictatorship between the 1970's and 1980's caused two things: a strong lag in local research and the migration of young investigators who learned abroad new disciplines and technologies. The coming back to democracy allowed for the return of some, now as solid researchers, and together with those who stayed, built a previously inexistent postgraduate training program and a globally-integrated academy that fostered diversity of research disciplines, including developmental biology. In this paper, we highlight the key contributions of pioneer researchers and the significant role played by academic and funding national institutions in the growth and consolidation of developmental biology in our country.

The olfactory epithelia arise from morphologically identifiable structures called olfactory placodes. Sensory placodes are generally described as being induced from the ectoderm suggesting that their development is separate from the coordinated cell movements generating the central nervous system. Previously, we have shown that the olfactory placodes arise from a large field of cells bordering the telencephalic precursors in the neural plate, and that cell movements, not cell division, underlie olfactory placode morphogenesis. Subsequently by image analysis, cells were tracked as they moved in the continuous sheet of neurectoderm giving rise to the peripheral (olfactory organs) and central (olfactory bulbs) nervous system (Torres-Paz and Whitlock, 2014). These studies lead to a model whereby the olfactory epithelia develop from within the border of the neural late and are a neural tube derivative, similar to the retina of the eye (Torres-Paz and Whitlock, 2014; Whitlock, 2008). Here we show that randomly generated clones of cells extend across the morphologically differentiated olfactory placodes/olfactory bulbs, and test the hypothesis that these structures are patterned by a different level of distal-less (dlx) gene expression subdividing the anterior neurectoderm into OP precursors (high Dlx expression) and OB precursors (lower Dlx expression). Manipulation of DLX protein and RNA levels resulted in morphological changes in the size of the olfactory epithelia and olfactory bulb. Thus, the olfactory epithelia and bulbs arise from a common neurectodermal region and develop in concert through coordinated morphological movements.

The molecular expression profiles of zebrafish ep2a and ep4b have not been defined to date. Phylogenetic trees of EP2a and EP4b in zebrafish and other species revealed that human EP4 and zebrafish EP4b were more closely related than EP2a. Zebrafish EP2a is a 281 amino acid protein which shares high identity with that of human (43%), mouse (44%), rat (43%), dog (44%), cattle (41%), and chicken (41%). Zebrafish EP4b encoded a 497 amino acid precursor with high amino acid identity to that of mammals, including human (57%), mouse (54%), rat (55%), dog (55%), cattle (56%), and chicken (54%). Whole-mount in situ hybridization revealed that ep2a was robustly expressed in the anterior four somites at the 10-somites stages, but was absent in the somites at 19 hpf. It was observed again in the pronephric duct at 24 hpf, in the intermediate cell mass located in the trunk, and in the rostral blood island at 30 hpf. Ep2a was also expressed in the notochord at 48 hpf. During somitogenesis, ep4b was highly expressed in the eyes, somites, and the trunk neural crest. From 30 to 48 hpf, ep4b could be detected in the posterior cardinal vein and the neighboring inner cell mass. From these data we conclude that ep2a and ep4b are conserved in vertebrates and that the presence of ep2a and ep4b transcripts during developmental stages infers their role during early zebrafish larval development. In addition, the variable expression of the two receptor isoforms was strongly suggestive of divergent roles of molecular regulation.

Background: The specific effect of SV40T on neurocytes has seldom been investigated by the researchers. We transfected Schwann cells (SCs) that did not have differentiation ability with MPH 86 plasmid containing SV40T, in order to explore the effects of SV40T on Schwann cells.

Methods: SCs were transfected with MPH 86 plasmid carrying the SV40T gene and cultured in different media, and also co-cultured with neural stem cells (NSCs). In our study, SCs overexpressing SV40T were defined as SV40T-SCs. The proliferation of these cells was detected by WST-1, and the expression of different biomarkers was analyzed by qPCR and immunohistochemistry.

Results: SV40T induced the characteristics of NSCs, such as the ability to grow in suspension, form spheroid colonies and proliferate rapidly, in the SCs, which were reversed by knocking out SV40T by the Flip-adenovirus. In addition, SV40T up-regulated the expressions of neural crest-associated markers Nestin, Pax3 and Slug, and down-regulated S100b as well as the markers of mature SCs MBP, GFAP and Olig1/2. These cells also expressed NSC markers like Nestin, Sox2, CD133 and SSEA-1, as well as early development markers of embryonic stem cells (ESCs) like BMP4, c-Myc, OCT4 and Gbx2. Co-culturing with NSCs induced differentiation of the SV40T-SCs into neuronal and glial cells.

Conclusions: SV40T reprograms Schwann cells to stem-like cells at the stage of neural crest cells (NCCs) that can differentiate to neurocytes.

There is growing demand for learning developmental biology in Latin America and a need for advanced students to interact with world leaders of this discipline. This article summarizes some of the efforts that Latin America is making to satisfy the demand in training young Latin American minds for the developmental biology of the future. I focus on a particular course that has been linked to the origins of the Latin America Society of Developmental Biology (LASDB). I describe the motivations to start organizing this course twenty years ago, its history and setbacks. We tracked back the current situation of former students to find out that more than 90% are still doing developmental biology all across the globe. I describe the state of affairs of the Course in its current location in the CIMARQ campus of the Universidad Andres Bello (UNAB), in a place called Quintay on the Chilean coast and I ask about its future.

The UNESCO Chair in Developmental Biology started in 1998, at the Institute of Biomedical Sciences of the Federal University of Rio de Janeiro, in Brazil. This Chair was a Brazilian-French initiative led by Professor Vivaldo Moura Neto and Professor Nicole Le Douarin, one of the most inspiring Developmental Biologists of the 20^th and 21^st centuries. The UNESCO Chair wanted to stimulate interest in Developmental Biology among Brazilian students and scientists by organizing annual international courses on Evolution and Developmental Biology at an advanced level. At the Federal University of Rio de Janeiro, the UNESCO Chair established an international laboratory for the permanent training of researchers and the development of research programs in Developmental Biology and related areas. Moreover, the program aimed at establishing an international network connecting Brazilian Universities and research centers in Latin America and Europe. The advanced hands-on courses, symposiums, and workshops promoted by this Chair inspired the careers of many young scientists. They generated new lines of research in Developmental Biology using a variety of animal models. This review does not intend to bring up all the historical events that marked the beginning of Developmental Biology in Brazil. Instead, it will be dedicated to highlighting one specific initiative that inspired a new generation of Developmental Biologists who established important research lines and contributed to the advance of this scientific field in Brazil.