Effects of a temperature-sensitiveMinutemutation on gene expression inDrosophila melanogaster

Abstract

SUMMARYMinute(M) lesions exhibit a striking propensity for interacting with many different mutations. In the past, few attempts have been made to explain these diverse phenomena. This study describes a variety of temperature-sensitive (ts) interactions exhibited by the ts third chromosomeMinutemutationM(3)LS4Q-III(Q-III). Most of these interactions (i.e. those involvingvg, cp, Dl, DfdorLy) reflectQ-III-induced enhancement of the respective mutant phenotypes at the restrictive temperature. However,Q-IIIalso suppresses the extra-sex-comb phenotypes ofPcandMscat 29 °C and evokes lethal and bristle traits when combined withJ34eat the restrictive temperature. All of these interactions are characteristic of non-tsMinutelesions and thus they appear to be correlated with general physiological perturbations associated with theMsyndrome. In addition, our findings show that mutations that affect ribosome production and/or function, namelysu(f)ts67gandbbts−1, exhibit interactions comparable to those elicited byQ-III. Hence, in accordance with previous findings, we argue that most of theQ-IIIinteractions can be attributed to reduced translational capacity at the restrictive temperature. Finally, reciprocal temperature shift studies were used to delineate TSPs for interactions betweenQ-IIIandvg(mid to late second instar),cp(about mid-third instar),Dfd(early third instar) andDl(late second to mid third instar). We believe that these TSPs represent developmental intervals during which the respective gene products are utilized.

A Genetic and Molecular Characterization of Two Proximal Heterochromatic Genes on Chromosome 3 of Drosophila melanogaster

“…Mutations in Minute genes have been shown to affect wing morphogenesis gene expression (Sinclair et al 1984;Hart et al 1993), and it has been proposed that this is due to the sensitivity of these genes to reductions in protein synthesis levels. The effect of lethal 2 on Notch is further enhanced in a genetic background in which a single dose of HP1 has been removed (Figure 11).…”

Genetic instability in Drosophila melanogaster: cytogenetic analysis of MR-induced X-chromosome deficiencies.

“…MR elements thus provide a genetic basis for the phenomena associated with the P-M system of "hybrid dysgenesis" (8,(14)(15)(16). It has also been claimed that MR factors and P factors are indistinguishable (16), and some studies have been predicated on this assumption (6).…”

“…MR elements thus provide a genetic basis for the phenomena associated with the P-M system of "hybrid dysgenesis" (8,(14)(15)(16). It has also been claimed that MR factors and P factors are indistinguishable (16), and some studies have been predicated on this assumption (6).We now report that MR elements can regularly produce massive deletions of most of the euchromatic part of the X chromosome at comparatively high frequencies in X chromosomes that are originally free of P elements. The deletion events, of the order of 15 million base pairs, are detected through the recovery offree X-chromosome duplications that retain the centromere and telomere but have most of the interstitial euchromatin deleted.…”

“…These elements generate elevated levels of mitotic crossing-over in premeiotic germ cells of both males and females (4)(5)(6) and also act as mutators by mostly facilitating the integration of P elements at various loci (7,8). It is also known that two MR-bearing chromosomes inherited patroclinously are no more potent than a single one in terms of mutator activity (9).…”

“…Furthermore, mapping of two second chromosome MR elements from sources as diverse as Haifa, Israel and Texas reveals very similar chromosomal locations in a short interval of <1 map unit (10,11). In addition, cytogenetic analyses have revealed that MR elements can generate deletions of up to several contiguous gene loci in the regions including the loci of lethal giant larva (12), net (12), cinnabar (12,13), black (12), purple (12), light (6), scarlet, and peach (M.M.G., unpublished data). They can also generate translocations and duplications (13).…”