Pigmentation and color pattern exhibit tremendous diversity among animals. This reflects that they are ecologically important traits being exposed to various selective pressure of natural selection. In vertebrates, melanin-based pigmentation system has been modified during individual species evolution for use in survival strategies such as crypsis, aposematism, and sexual display. Understanding the generation of phenotypic diversity among animals requires defining the genetic changes involved. Coat color mutations in laboratory mice have served as a premier model for studying gene action in a variety of biological processes, leading to a wealth of information about genes involved in pigmentation. A deep understanding of mouse coat color genetics helps us study the molecular basis of pigmentation system in other vertebrates. Here, we introduce recent progress in our understanding of the molecular mechanism of melanin-based pigmentation in birds. Identification and characterization of genes encoded by feather pigmentation loci revealed that the melanin-based pigmentation system is highly conserved between birds and mammals. Furthermore, it is suggested that the intra-feather germ melanocortin system plays a crucial role in generating complicated color patterns in both individual feathers and plumage. Based on these findings, we hypothesize that changes in the regulation of expression of melanocortin system component genes partially contribute in generating phenotypic diversity in pigmentation between birds and mammals.

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Learning and memory are fundamental higher brain functions that allow an animal to adapt to the environment. Studies in a variety of animals such as mollusks, insects and mammals have shown that memories contain various phases from short-term memories in the range of minutes to long-term memories lasting a lifetime. Different intercellular molecules have been implicated in distinct aspects of learning and memory formation. For convenience, these molecules are sometimes termed ‘memory molecules’. Insects have high learning ability despite their simple nervous systems with relatively small number of neurons, and thus are suitable for studying learning and memory. Specifically, fruit fly Drosophila melanogaster is one of the well-studied animals in the field of memory molecules. The application of the mutagenic approach to the study of olfactory learning and memory in Drosophila has yielded insights into the participation of numerous memory molecules. In this review, we briefly describe memory mutants in Drosophila and the molecular mechanisms that contribute to the various forms of memory.

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