Localized ultraviolet laser microbeam irradiation of early Drosophila embryos: Fate maps based on location and frequency of adult defects

Abstract

Drosophila embryos were locally irradiated with a 257-nm laser mierobeam during blastoderm and germ band stages. Depending on stage and beam diameter (10-30 pm), from 0 to 45 nuclei were exposed to the uv radiation. The doses used, 5 or 10 erg, did not eliminate nuclei or cells at onee, but up to 50% of the adult survivors from irradiated eggs carried defects in the thorax. These were scored with reference to the imaginal discs from which the affected structures derive. For each thoracic disc a "target center" was calculated as the weighted mean value of all beam locations affecting the respective adult derivatives. The target centers for the germ band stage map within the respective germ band segments. The pattern of target centers for the blastoderm stage is comparable to the thoracic region of published fate maps, and the distances between adjacent leg centers (approximately three cell diameters) agree with recent evidence based on mosaic flies. We discuss the question whether the target centers mark the position of the respective disc progenitor cells at the stages of irradiation and conclude that these positions are rendered rather correctly at least with reference to the longitudinal egg aJcis.

Pattern formation in the Drosophila embryo

“…The adult abdomen derives from the histoblasts. From the use of gynandromorphs (Garcia-Bellido & Merriam 1969;Hotta & Benzer 1972;Janning 1978;Merriam 1978), and direct experiments based on microdeletion (Bownes & Sang 1974 b),microcautery (Bownes & Sang 1974 a;Bownes 1975), microturbulence (Bedian et al 1981) and localized ultraviolet irradiation (Lohs-Schardin et al 1979 a, ), a detailed fate map of the anlagen for adult ectodermal structures on the blastoderm has been constructed (figure 1). Adult ectodermal derivatives are formed from bilateral bands of cells extending along the lateral equator of the egg from about 20 % egg length to about 80 % egg length, measured from the posterior pole.…”

Towards Ultraviolet Microbeam Scanning and Lens-Less UV Microbeam Microscopy with Mirror Galvanometric Scanners: From the History of Research Instrumentation to Engineering of Modern Mechatronic Optical Systems

“…The microbeam applications to the experimental morphological studies have been expanding. In the 1970-1980s the microbeam effects were macroscopic or mesoscopic with the morphological results achieved by the direct effects on the organism or its embryo, while nowadays the same results are achieved with a "molecular resolution" by genetic switches or changes in the membrane ion channel operation [60][61][62]. In neuromorphology, where UV microbeams were used for control and inhibition of the cell and tissue differentiation since the 1980s, an optogenetic trend has emerged which is based on the optical stimulation of the light-gated ion channels embedded into the cell membrane (e.g., opsins) with the genetic engineering methods used to express such channels [63].…”

FLPing Genes On and Off in Drosophila

“…Using externally visible markers such as bristle shape and body pigments, he and others generated developmental fate maps in which the origin of individual adult structures such as the eyes, antennae, legs, and wings could be traced with a fair degree of precision back to regions of the embryonic blastoderm (Baker, 1978; Garcia-Bellido and Merriam, 1969; Parks, 1936; Patterson and Stone, 1938; Ripoll, 1972; Sturtevant, 1929). The use of this genetic system replaced other efforts to trace development such as cell ablation and histological analysis (Geigy, 1931; Howland and Child, 1935; Lohs-Schardin et al, 1979a; Lohs-Schardin et al, 1979b; Poulson, 1950). Other uses for gynandromorphs included the determination of where genes were acting.…”