Amanda Dickinson

My focus in the lab is to study the formation of the mouth, using the amphibian, Xenopus as a model. The importance of the mouth is apparent; it is necessary for feeding, communication and breathing and also likely influences the development of surrounding structures such as craniofacial features, teeth, tongue and pituitary gland. Many different developmental abnormalities may, therefore, be attributed to the disruption of genes involved in mouth formation. The oral cavity forms from a unique, mesoderm-free region of the late gastrula where extreme anterior ectoderm directly contacts endoderm of the future gut to form the presumptive mouth or stomodeum. Later, the stomodeal ectodermal and underlying endodermal layers break through to form the mouth cavity that is continuous with the gut. While some features of stomodeal embryology have been examined in several vertebrate species, virtually nothing is known about the genes necessary to direct mouth formation. Therefore, I am using both molecular and embryological techniques to examine the mechanisms governing stomodeal and later mouth development. Having a background in invertebrate developmental biology, I am also interested in using developmental processes to gain insights into evolution. The mouth is an ideal structure to study in this regard, since the mouth region is thought to be conserved across the deuterostomes. Therefore, as a long term goal, I am also interested in comparing stomodeal formation in other species to help provide insights into the evolution of the mouth.

Figure: Frontal view of a tailbud stage of Xenopus as the mouth is forming.

Jennifer Gutzman

The developing vertebrate hindbrain ultimately forms the adult cerebellum and brainstem. This area of the brain gives rise to 8 of 12 pairs of cranial nerves important in control of muscles in the jaw, eye, and face, is critical for communication with the spinal cord to coordinate movement, and for involuntary actions such as respiration and heartbeat. Along the anterior-posterior (AP) axis of the developing embryo, segments termed rhombomeres are the basis for later organization and specification of these neuronal connections. I am using the zebrafish as a model for investigating rhombomere neuronal patterning. Zebrafish maintain a brain structure that is similar to other vertebrates, including humans, making this an excellent model for many human disorders. Furthermore, molecular and genetic techniques have been developed for the zebrafish by many labs, including the Sive lab, that allow for gain-of-function and loss-of-function experiments to test gene function. These attributes and the genetics tools available make the zebrafish an exceptional model for studying brain development. Multiple genes are required to form specific rhombomere domains. During gastrulation the future hindbrain is divided into anterior (future r1-r4) and posterior (future r5-r7) domains. Later during somitogenesis, broad domains of early gene expression become sequentially narrowed as rhombomeric territories are set aside. Genes with known specific rhombomere expression patterns provide useful tools to investigate rhombomere identity and the signals that influence their expression (Fig.1). Two interesting genes, nlz1/2 and iroquios 7, have been shown to be critical for normal hindbrain patterning. I am currently interested in these genes and their interaction in determination of rhombomere 4 identity during early and late hindbrain development. My goal is to integrate the understanding of basic mechanisms of hindbrain development with definition of the genetics involved with the potential to identify genes involved in malformations, neuronal degeneration and other neuronal diseases of this important brain region.