David J. Lampe

A purified mariner transposase is sufficient to mediate transposition in vitro

Mariners are a widespread and diverse family of animal transposons. Extremely similar mariners of the irritans subfamily are present in the genomes of three divergent insect host species, which strongly suggests that species-specific host factors are unnecessary for mobility. We tested this hypothesis by examining the activity of a purified transposase from one of these elements (Himar1) present in the horn fly, Haematobia irritans. Himar1 transposase was sufficient to reproduce transposition faithfully in an in vitro inter-plasmid transposition reaction. Further analyses showed that Himar1 transposase binds to the inverted terminal repeat sequences of its cognate transposon and mediates 5 and 3 cleavage of the element termini. Independence of species-specific host factors helps to explain why mariners have such a broad distribution and why they are capable of horizontal transfer between species.

Expression of lacunin, a large multidomain extracellular matrix protein, accompanies morphogenesis of epithelial monolayers in Manduca sexta.

Morphogenesis is a complex process operating at several levels of organization--organism, tissues, cells, and molecules. Complex interactions occur between and within these levels. Many of the molecules that mediate these interactions are predictably turning out to be large multidomain proteins. Here we describe one such novel protein associated with remodeling of epithelial monolayers in embryos and developing wings of the moth Manduca sexta. On the basis of its sequence and its expression pattern along lacunae of developing wings, we propose the name lacunin for this extracellular matrix protein that contains nine different types of domains, most of which are present in multiple copies. These include domains of various types: Kunitz proteinase inhibitors, thrombospondin type I, immunoglobulin-like, and several newly defined domains of unknown function (PAL, PLAC, and lagrin domains). This rich patchwork of distinct domains probably exerts multiple effects on a variety of cell behaviors associated with the complex phenomenon of epithelial morphogenesis.

Characterization of a cDNA and gene encoding a cuticular protein from rigid cuticles of the giant silkmoth, Hyalophora cecropia

We have isolated a cDNA and gene encoding a protein (HCCP66) found in the rigid cuticles of both larvae and pupae of the silkmoth, Hyalophora cecropia. The cDNA encoded a protein similar to cuticle proteins isolated from several other insects and contained a sequence motif similar to one present in a family of cuticular proteins from flexible cuticles. The gene had a structure similar to that of cuticle protein genes isolated from Drosophila melanogaster, albeit with a much larger intron that contained three copies of a transposable element-like sequence similar to short interspersed repeated DNA elements (SINEs). A sequence found 5 to the transcription start site matched the Octamer (Oct) cis-acting element. This sequence was capable of binding protein(s) from whole cell extracts of wing epidermis with high affinity and sequence specificity suggesting a role in transcriptional regulation.

The mariner Transposons of Animals: Horizontally Jumping Genes

Publisher Summary This chapter discusses the mariner transposons of animals. The mariner transposons of insects and other animals are now known to comprise a large family of small transposable elements characterized by a D, D34D catalytic domain in their encoded transposases. In most cases, these mariners evolve neutrally and accumulate incapacitating mutations within particular hosts, whereas comparisons between hosts indicate that most of the evolutionary conservation of their transposase genes occurs in conjunction with the horizontal transfers between hosts. The ability of mariner transposase to catalyze transposition without species-specific host factors appears to allow this unusual evolutionary pattern. Mariners and the related Tc1 family of transposons, which evidence many of these same characteristics, have, thereby affected the composition of most animal genomes. In the initial phylogenetic analyses of mariner relationships, it was clear that horizontal transfers across large host phylogenetic distances, such as orders of insects, must have occurred.

The mariner Transposons of Animals

Publisher Summary This chapter discusses the mariner transposons of animals. The mariner transposons of insects and other animals are now known to comprise a large family of small transposable elements characterized by a D, D34D catalytic domain in their encoded transposases. In most cases, these mariners evolve neutrally and accumulate incapacitating mutations within particular hosts, whereas comparisons between hosts indicate that most of the evolutionary conservation of their transposase genes occurs in conjunction with the horizontal transfers between hosts. The ability of mariner transposase to catalyze transposition without species-specific host factors appears to allow this unusual evolutionary pattern. Mariners and the related Tc1 family of transposons, which evidence many of these same characteristics, have, thereby affected the composition of most animal genomes. In the initial phylogenetic analyses of mariner relationships, it was clear that horizontal transfers across large host phylogenetic distances, such as orders of insects, must have occurred.

Chapter 16 – The mariner Transposons of Animals: Horizontally Jumping Genes

Publisher Summary This chapter discusses the mariner transposons of animals. The mariner transposons of insects and other animals are now known to comprise a large family of small transposable elements characterized by a D, D34D catalytic domain in their encoded transposases. In most cases, these mariners evolve neutrally and accumulate incapacitating mutations within particular hosts, whereas comparisons between hosts indicate that most of the evolutionary conservation of their transposase genes occurs in conjunction with the horizontal transfers between hosts. The ability of mariner transposase to catalyze transposition without species-specific host factors appears to allow this unusual evolutionary pattern. Mariners and the related Tc1 family of transposons, which evidence many of these same characteristics, have, thereby affected the composition of most animal genomes. In the initial phylogenetic analyses of mariner relationships, it was clear that horizontal transfers across large host phylogenetic distances, such as orders of insects, must have occurred.