Mqo, a tricarboxylic acid cycle enzyme, is required for virulence of Pseudomonas syringae pv. tomato strain DC3000 on Arabidopsis thaliana.

Plant pathogenic bacteria, such as Pseudomonas syringae pv. tomato strain DC3000, the causative agent of tomato bacterial speck disease, grow to high levels in the apoplastic space between plant cells. Colonization of plant tissue requires expression of virulence factors that modify the apoplast to make it more suitable for pathogen growth or facilitate adaptation of the bacteria to the apoplastic environment.

Zebrafish melanophilin facilitates melanosome dispersion by regulating dynein.

Background: Fish melanocytes aggregate or disperse their melanosomes in response to the level of intracellular cAMP. The role of cAMP is to regulate both melanosome travel along microtubules and their transfer between microtubules and actin. The factors that are downstream of cAMP and that directly modulate the motors responsible for melanosome transport are not known.

pyewacket, a new zebrafish fin pigment pattern mutant.

Many mutants that disrupt zebrafish embryonic pigment pattern have been isolated, and subsequent cloning of the mutated genes causing these phenotypes has contributed to our understanding of pigment cell development. However, few mutants have been identified that specifically affect development of the adult pigment pattern. Through a mutant screen for adult pigment pattern phenotypes, we identified pyewacket (pye), a novel zebrafish mutant in which development of the adult caudal fin pigment pattern is aberrant.

kitb, a second zebrafish ortholog of mouse Kit.

The large numbers of duplicated pairs of genes in zebrafish compared to their mammalian counterparts has lead to the notion that expression of zebrafish co-orthologous pairs in some cases can together describe the expression of their mammalian counterpart. Here, we explore this notion by identification and analysis of a second zebrafish ortholog of the mammalian Kit receptor tyrosine kinase (kitb). We show that in embryos, kitb is expressed in a non-overlapping pattern to that of kita, in the anterior ventral mesoderm, Rohon-beardRohon-Beard neurons, the otic vesicle, and trigeminal ganglia.

A requirement for kit in embryonic zebrafish melanocyte differentiation is revealed by melanoblast delay.

Exploring differences in gene requirements between species can allow us to delineate basic developmental mechanisms, provide insight into patterns of evolution, and explain heterochronic differences in developmental processes. One example of differences in gene requirements between zebrafish and mammals is the requirement of the kit receptor tyrosine kinase in melanocyte development. kit is required for migration, survival and differentiation of all neural crest-derived melanocytes in mammals.

The evolution of morphological complexity in zebrafish stripes.

The zebrafish pigment stripe pattern is a complex tissue containing iridophores, xanthophores and multiple melanocyte types. Mutational analysis reveals that both ancient and recent gene duplications are involved in the generation or maintenance of the pattern complexity. Receptor tyrosine kinases kit and fms, products of an ancient gene duplication, are required in distinct types of melanocytes and xanthophores.