materials and methods the l. tropica strain was attenuated using continuous passaging 20 times. the infectivity of l. tropica was confirmed in balb/c mice. the l. tropica resistant strain was produced in vitro using a continuous increase in drug pressure. the cross resistance of l. tropica to other drugs was also investigated. results after 20 continuous passages, the balb/c mice tested negativ...

The biosynthetic pathways and multiple functions of purine nucleotides are well known. However, the pathways that respond to alterations in purine nucleotide synthesis in vivo in an animal model organism have not been identified. We examined the effects of inhibiting purine de novo synthesis in vivo and in cultured cells of Drosophila melanogaster. The purine de novo synthesis gene ade2 encodes...

The anlagen of imaginal histoblasts in the abdominal segments of Calliphora (higher Diptera) present an interesting problem, which bears on recent concepts employed in the consideration of spatial patterning in insects. They differ from imaginal discs with respect to larval organization and activity, and in the absence of the progressive pattern of genetic determination during the larval period...

The wing imaginal disc of Drosophila melanogaster is a prominent experimental system for research on control of cell growth, proliferation and death, as well as on pattern formation and morphogenesis during organogenesis. The precise genetic methodology applicable in this system has facilitated conceptual advances of fundamental importance for developmental biology. Experimental accessibility a...

The segment polarity genes of Drosophila were initially defined as genes required for pattern formation within each embryonic segment. Some of these genes also function to establish the pattern of the adult cuticle. We have examined the role of the armadillo (arm) gene in this latter process. We confirmed and extended earlier findings that arm and the segment polarity gene wingless are very sim...

We isolated and characterized embryonic lethal mutations in piragua (prg). The prg locus encodes a protein with an amino terminus Zinc Finger-Associated-Domain (ZAD) and nine C2H2 zinc fingers (ZF). prg mRNA and protein expression during embryogenesis is dynamic with widespread maternal contribution, and subsequent expression in epithelial precursors. About a quarter of prg mutant embryos do no...

IN the previous communication (Yao, 1949ft), alkaline phosphatase has been shown to be in some way connected with histo-differentiation during Drosophila embryogenesis. The post-embryonic development of Drosophila includes, besides a period of larval growth, the phenomenon of metamorphosis which involves the destruction of most larval organs and the simultaneous development of imaginal organs f...

A proneural cluster of dorsocentral bristles forms adjacent to the dorsal side of wg-expressing cells in the notum region of the wing imaginal disc. It has been shown that wg activity is required for these structures to form. However, the restriction of this proneural cluster to the dorsal posterior side of the wg expression domain in the anterior compartment of the wing imaginal disc has sugge...