A challenge-based interdisciplinary undergraduate concept fostering translational medicine.

Translational medicine (TM) is an interdisciplinary branch of biomedicine that bridges the gap from bench-to-bedside to improve global health. Fundamental TM skills include interdisciplinary collaboration, communication, critical thinking, and creative problem-solving (4Cs). TM is currently limited in undergraduate biomedical education programs, with little patient contact and opportunities for collaboration between different disciplines. In this study, we developed and evaluated a novel interdisciplinary challenge-based educational concept, grounded in the theoretical framework of experimental research-based education, to implement TM in undergraduate biomedicine and medicine programs. Students were introduced to an authentic clinical problem through an interdisciplinary session with patients, medical doctors, and scientists. Next, students collaborated in groups to design unique laboratory-based research proposals addressing this problem. Stakeholders subsequently rewarded the best proposal with funding to be executed in a consecutive interdisciplinary laboratory course, in which mixed teams of biomedicine and medicine students performed the research in a fully equipped wet laboratory. Written questionnaires and focus groups revealed that students developed 4C skills and acquired a 4C mindset. Working on an authentic patient case and the interdisciplinary setting positively contributed to communication, collaboration, critical thinking, and creative problem-solving skills. Furthermore, students were intrinsically motivated by (i) the relevance of their work that made them feel taken seriously and competent, (ii) the patient involvement that highlighted the societal relevance of their work, and (iii) the acquisition of a realistic view of what doing science in a biomedical research laboratory is. In conclusion, we showcase a widely applicable interdisciplinary challenge-based undergraduate concept fostering TM.

A novel undergraduate biomedical laboratory course concept in synergy with ongoing faculty research.

Optimal integration of education and ongoing faculty research in many undergraduate science programs is limited to the capstone project. Here, we aimed to develop a novel course-based undergraduate research experience (CURE) in synergy with ongoing faculty research. This 10-week course called Biomedical Research Lab is embedded in the curriculum of the undergraduate program Biomedical Sciences and grounded in the theoretical framework of research-based learning. Four groups of four students work together in a dedicated laboratory on an actual ongoing research problem of faculty. All groups work on the same research problem, albeit from different (methodological) perspectives, thereby stimulating interdependence between all participants. Students propose new research, execute the experiments, and collectively report in a single research article. According to students, the course enhanced scientific, laboratory, and academic skills. Students appreciated ownership and responsibilities of the research, laboratory teachers as role models, and they were inspired and motivated by doing authentic actual research. The course resulted in a better understanding of what doing research entails. Faculty valued the didactical experience, research output and scouting opportunities. Since topics can change per course edition, we have showcased a widely applicable pedagogy creating synergy between ongoing research and undergraduate education.

Brefeldin A or monensin inhibits the 3D organizer in gastropod, polyplacophoran, and scaphopod molluscs.

In molluscs, the 3D vegetal blastomere acts as a developmental signaling center, or organizer, and is required to establish bilateral symmetry in the embryo. 3D is similar to organizing centers in other metazoans, but detailed comparisons are difficult, in part because its organizing function is poorly understood. To elucidate 3D function in a standardized fashion, we used monensin and brefeldin A (BFA) to rapidly and reversibly interfere with protein processing and secretion, thereby inhibiting the signaling interactions that underlie its specification and patterning. In the gastropods, Patella vulgata and Lymnaea stagnalis, the polyplacophoran, Mopalia muscosa, and the scaphopod, Antalis entalis, treatments initiated before the organizer-dependent onset of bilateral cleavage resulted in radialization of subsequent development. In radialized P. vulgata, L. stagnalis, and M. muscosa, organizer specification was blocked, and embryos failed to make the transition to bilateral cleavage. In all four species, the subsequent body plan was radially symmetric and was similarly organized about a novel aboral-oral axis. Our results demonstrate that brefeldin A (BFA) and monensin can be used to inhibit 3D's organizing function in a comparative fashion and that, at least in M. muscosa, the organizer-dependent developmental architecture of the embryo predicts subsequent patterns of morphogenetic movements in gastrulation and, ultimately, the layout of the adult body plan.

Brefeldin A and monensin inhibit the D quadrant organizer in the polychaete annelids Arctonoe vittata and Serpula columbiana.

The D quadrant organizer is a developmental signaling center that is localized to the vegetal D quadrant in different spiral-cleaving lophotrochozoan embryos and may be homologous to axial organizing regions in other metazoans. Patterning by this organizing center creates a secondary developmental axis and is required for the transition from spiral to bilateral cleavage and later establishment of the adult body plan. Organizer specification in equal-cleaving embryos is thought to involve inductive interactions between opposing animal and vegetal blastomeres. To date, experimental demonstration of this interaction has been limited to molluscs and nemerteans. Here, we examine three families of equal-cleaving polychaete annelids for evidence of animal-vegetal contact. We find that contact is present in the polynoid, Arctonoe vittata, but is absent in the serpulid, Serpula columbiana, and in the oweniid, Oweniia fusiformis. To interfere with cell signaling during the period predicted for organizer specification and patterning in A. vittata and S. columbiana, we use two general inhibitors of protein processing and secretion: Brefeldin A (BFA) and monensin. In A. vittata, we detail subsequent embryonic and larval adult development and show that treatment with either chemical results in radialization of the embryo and subsequent body plan. Radialized larvae differentiate many larval and adult structures despite the loss of bilateral symmetry but do so in either a radially symmetric or four-fold radially symmetric fashion. Our results suggest that the D quadrant organizer is functionally conserved in equal-cleaving polychaetes, but that details of its specification, induction, and patterning have diverged relative to other spiral-cleaving phyla.

Cell-lineage analysis of the prototroch of the gastropod molluscPatella vulgata shows conditional specification of some trochoblasts.

Embryos of many spirally cleaving species possess a characteristic cell type, the trochoblasts. These cells differentiate early in development into ciliated cells and give rise to the prototroch, the locomotory organ of the trochophore larva. As a necessary prelude to the investigation of the mechanisms that are responsible for specification of trochoblasts in the equally cleaving gastropod molluscPatella vulgata, the cell-lineage of the prototroch was studied. This was done by microinjection of the cell-lineage tracer lucifer yellow-dextran in trochoblasts and by scanning electron microscopical analysis of formation of the prototroch. The results show that trochoblasts that form the prototroch are of different clonal origin and that the four quadrants of the embryo have an unequal contribution to the prototroch. Since the four quadrants of the equally cleaving embryo are initially equipotent, some trochoblasts must become conditionally specified. Other trochoblasts seem to become autonomously specified. After initial ciliation some trochoblasts become deciliated and for some cells the choice between a larval and an adult cell fate is conditionally specified. Cell-lineage analysis demonstrates that the various autonomously and conditionally specified trochoblasts are organised according to the dorsoventral axis of the embryo. Possible mechanisms that can account for the conditional specification of trochoblasts - including a role for the 3D macromere, which forms the primary mesoderm and is responsible for the formation of the dorsoventral axis of the embryo - are discussed.

Expression of Patella vulgata orthologs of engrailed and dpp-BMP2/4 in adjacent domains during molluscan shell development suggests a conserved compartment boundary mechanism.

The engrailed gene is well known from its role in segmentation and central nervous system development in a variety of species. In molluscs, however, engrailed is involved in shell formation. So far, it seemed that engrailed had been co-opted uniquely for this particular process in molluscs. Here, we show that, in the gastropod mollusc Patella vulgata, an engrailed ortholog is expressed in the edge of the embryonic shell and in the anlage of the apical sensory organ. Surprisingly, a dpp-BMP2/4 ortholog is expressed in cells of the ectoderm surrounding, but not overlapping, the engrailed-expressing shell-forming cells. It is also expressed in the anlage of the eyes. Earlier it was shown that a compartment boundary exists between the cells of the embryonic shell and the adjacent ectoderm. We conclude that engrailed and dpp are most likely involved in setting up a compartment boundary between these cells, very similar to the situation in, for example, the developing wing imaginal disc in Drosophila. We suggest that engrailed became involved in shell formation because of its ancestral role, which is to set up compartment boundaries between embryonic domains.

Evolutionary biology: hedgehog crosses the snail's midline.

According to the dorsoventral axis-inversion theory, protostomes (such as insects, snails and worms) are organized upside-down by comparison with deuterostomes (vertebrates), in which case their respective ventrally (belly-side) and dorsally (back-side) located nervous systems, as well as their midline regions, should all be derived from a common ancestor. Here we provide experimental evidence for such homology by showing that an orthologue of hedgehog, an important gene in midline patterning in vertebrates, is expressed along the belly of the larva of the limpet Patella vulgata. This finding supports the existence of a similar mechanism for the development of the midline of the nervous system in protostomes and deuterostomes.

Characterisation of two snail genes in the gastropod mollusc Patella vulgata. Implications for understanding the ancestral function of the snail-related genes in Bilateria.

Snail genes have been found to play a role in mesoderm formation in two of the three clades of bilaterians, deuterostomes (comprising the chordates) and ecdysozoans (comprising the arthropods). No clear data are available on the role these genes play in development of the mesoderm in the third clade, that of lophotrochozoans (comprising annelids and molluscs). We identified two new members of the snail gene family in the gastropod mollusc Patella vulgata. Phylogenetic analysis showed that the two genes clearly belong to the snail sub-family. Their expression patterns do not indicate a role during early mesoderm formation. In fact, contrary to expectations, the snail genes of Patella were mostly expressed in the ectoderm. In view of the location of their expression sites, we suggest that these genes could be involved in regulating epithelial-mesenchymal transitions (EMT) and cell motility, as has recently been demonstrated for snail genes in vertebrates. This may well correspond to the ancestral function of these genes. The results are discussed in the light of the evolutionary origin of the mesoderm. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00427-002-0228-1.

A lophotrochozoan twist gene is expressed in the ectomesoderm of the gastropod mollusk Patella vulgata.

The twist gene is known to be involved in mesoderm formation in two of the three clades of bilaterally symmetrical animals: viz. deuterostomes (such as vertebrates) and ecdysozoans (such as arthropods and nematodes). There are currently no data on the spatiotemporal expression of this gene in the third clade, the lophotrochozoans (such as mollusks and annelids). To approach the question of mesoderm homology across bilaterians, we decided to analyze orthologs of this gene in the gastropod mollusk Patella vulgata that belongs to the lophotrochozoans. We present here the cloning, characterization, and phylogenetic analysis of a Patella twist ortholog, Pv-twi, and determine the early spatiotemporal expression pattern of this gene. Pv-twi expression was found in the trochophore larva in a subset of the ectomesoderm, one of the two sources of mesoderm in Patella. These data support the idea that twist genes were ancestrally involved in mesoderm differentiation. The absence of Pv-twi in the second mesodermal source, the endomesoderm, suggests that also other genes must be involved in lophotrochozoan mesoderm differentiation. It therefore remains a question if the mesoderm of all bilaterians is homologous.

Novel and conserved roles for orthodenticle/ otx and orthopedia/ otp orthologs in the gastropod mollusc Patella vulgata.

The orthodenticle/ otx and orthopedia/ otp classes of homeobox gene families have been identified in all three major classes of bilaterians: deuterostomes, lophotrochozoans, and ecdysozoans. Otx genes have been studied extensively and play a role in the development of anterior neural structures. Otp genes have been found to be involved in nervous system development in mouse and Drosophila. To date, no members of these genes are known in molluscs. We cloned orthologs of orthodenticle/ otx and orthopedia/ otpfrom the gastropod Patella vulgata, and designated them Pv-otx and Pv-otprespectively. Our analysis of the spatio-temporal expression pattern of otx and otp orthologs during P. vulgata embryogenesis leads to the following conclusions. First, Pv-otx is expressed in and around the stomodaeum and our analysis thus supports the previously suggested conservation of the protostome and deuterostome larval mouth regions. Second, we find that Pv-otp is involved in the development of the larval apical sensory organ, suggesting a conserved role for this gene family in nervous system development. A similar conserved role in nervous system development has been proposed for orthodenticle/otx genes and we suggest that part of the cells expressing Pv-otx are involved in the development of the anterior nervous system. Last, we postulate that otx genes were ancestrally involved in the development of ciliary bands in bilaterians.