In a recent study we carried out an exhaustive search of – and -keratin genes in the Galgal4 genome assembly and characterized the expression pattern of some keratin genes. damaged patterns during regenerative wound healing and for tissue engineering to rebuild tissues. gradient (Driever and Nusslein-Volhard. 1988; Houchmandzadeh, et al. 2002), vein formation of imaginal discs in flies (Lander, et Pindolol al. 2002) and specification of neuronal precursor domains determined by a gradient (Dessaud, et al. 2008). Autonomous pattern formation has been described by two major modeling frameworks. One model is based on spontaneous pattern formation driven by reactions and diffusions of at least two biochemical substances proposed by Alan Turing (Turing. 1952) and its derivative theories (Gierer and Meinhardt. 1972). In such models, one central mechanism driving patterning is based upon short-range activation and long-range inhibition. The second model framework involves mechanics, such as the buckling instability of elastomers (Moulton and Goriely. 2011) in which competition between geometric effects (e.g. the change in tube dimensions) and mechanical effects (e.g. residual stress due to differential growth) create patterns. The details of these theories will be described later in this review. Pindolol It is likely that different types of molecular circuits evolved in a convergent manner to produce similar biological patterns. Some molecular circuits may be based on transcription activity in the genome, some may be based on the threshold response to a morphogen gradient, othersmay Rabbit polyclonal to Anillin be based on the cell interactions in combination with physical-chemical forces. We speculate that the mechanism underlying Drosophila segmentation may be more rigid and specific, since genetic changes are needed to make a new segmentation pattern. While the mechanism regulating feather / hair periodic patterning is more plastic, since the same number of appendage forming progenitors can be modulated to form 10 big hairs or 1000 small hairs, depending on the environmental cues present. To perfect the outcomes of tissue engineering, we will need to learn more about the principles of morphogenesis, to understand how patterns initiate, develop, and become stabilized at the cellular and molecular circuit levels while the system faces great environmental or genetic fluctuations. The fact that disrupting molecule X interferes with the formation of a certain pattern only indicates that molecule X is involved in this process. To understand the specific role of X we need to detect its spatial distribution, determine which molecules crosstalk with it, and how these molecules are quantitatively affected. This information Pindolol will reveal the role of X in the context of a specific mechanism. For example, one needs to know if X is an activator, an inhibitor, a modulator for robustness of patterning, or simply a regulator of the activator and/or the inhibitor. In addition, knowledge of the detailed temporal dynamic cellular process becomes very important in obtaining any detailed mechanisms of patterning. Since the integument develops at the body surface and displays a variety of striking patterns that are convenient to observe and experimentally manipulate, as opposed to visceral organs, the integument has become one of the leading model systems for elucidating mechanisms of pattern formation. Next, we discuss pattern formation by using the integument model as a Rosetta stone to decipher the language of morphogenesis. PERIODIC PATTERN FORMATION IN INTEGUMENTARY ORGANS: MULTIPLICITY ALLOWS VARIABILITY Integument organs such as hairs, feathers, scales, claws, beaks, teeth, epidermal glands, etc, not only create a boundary between the organism and the environment but also facilitate organismal adaptation to diverse environmental conditions while providing communication between individuals of the same and other species (Fig. 1). Many integumentary organs are composed of several organ primordia that work together as an organ population. For example, there are multiple numbers of mammalian teeth, multiple glands, and thousands of hairs and feathers (Fig. 2B). This multiplicity allows the animal to make variations in different body regions, and thus make integument organs from different regions exhibit regional- and age- specific phenotypes so they adapt to the environment robustly (Chuong et al., 2013). We will first review the current knowledge on how integument organs form a patterned population. Open in a separate window Fig. 1 Sphinx of integumentary organsA Greek version of a Sphinx is used to symbolize the riddle on.