The mutant phenotype associated with P-element alleles of the vestigial locus in Drosophila melanogaster may be caused by a readthrough transcript initiated at the P-element promoter

We report here the isolation of a new P-element-induced allele of the vestigial locus vg(2a33), the molecular characterization of which allows us to propose a unifying explanation of the phenotypes of the large number of vestigial P-element alleles that now exists. The first P-element allele of vestigial to be isolated was vg(21), which results in a very weak mutant wing phenotype that is suppressed in the P cytotype. By destabilizing vg(2a33) in a dysgenic cross, we isolated the vg(2a33) allele, which exhibits a moderate mutant wing phenotype and is not suppressed by the P cytotype. The new allele is characterized by a 46-bp deletion that removes the 3'-proximal copy of the 11-bp internal repeat from the P element of vg(21). To understand how this subtle difference between the two alleles leads to a rather pronounced difference in their phenotypes, we mapped both the vg and P-element transcription units present in wild type and mutants. Using both 5'-RACE and S1 protection, we found that P-element transcription is initiated 19 bp farther upstream than previously thought. Using primer extension, the start of vg transcription was determined to lie 435 bp upstream of the longest cDNA recovered to date and upstream of the P-element insertion site. Our discovery that the P element is situated within the first vg exon has prompted a reassessment of the large body of genetic data on a series of alleles derived from vg(21). Our current hypothesis to explain the degree of variation in the mutant phenotypes and their response to the P repressor invokes a critical RNA secondary structure in the vg transcript, the formation of which is hindered by a readthrough transcript initiated at the P-element promoter.

The University of Maryland Medical System invests in its community's minorities

As a private, non-state-owned teaching hospital adjacent to a predominately low income African American community in Baltimore, the University of Maryland Medical System (hereafter called the Medical System) in partnership with the state's medical school has historically provided excellent medical care to the community's residents regardless of their ability to pay. Nevertheless, executive leadership recognized that the Medical System needed to be even more socially and economically responsible to the minority community by investing more of the system's resources in that community. Doing so would improve the economic strength of the community, and this strength would help the Medical System to continue to thrive and expand its business in Baltimore City. Therefore, in the late 1980s, the Medical System created a program that focuses on greater inclusion of minorities particularly African Americans, in personnel, construction, purchasing, and community outreach. In the area of personnel, recruitment efforts have focused on increasing the representation of minorities, particularly African Americans, in management and residency positions. The result has been the creation of a more supportive environment for minority personnel throughout the organization as well as for minority patients and vendors who have dealings with the medical system. In the area of construction, minority development efforts have included the establishment of a flexible bid-award policy and a partnership with the minority business community. As a result, total construction dollars spent with minority-owned firms increased from $2 million to $18 million over seven years, and the portion of these dollars spent with African American-owned firms increased sixfold. In the area of purchased goods and services, more creative approaches to improving minority participation have been necessary. These have included partnering minority distributors with major suppliers and literally assisting in the creation of new minority firms capable of effectively responding to the competitive marketplace. As a result, purchasing dollars spent with minority-owned firms increased from $1.5 million to $3.2 million in four years, and the portion of these dollars spent with African American-owned firms nearly tripled. In community outreach, a comprehensive program has emerged that includes education, career development, disease prevention, and health promotion activities. The Medical System has encountered many barriers to success in these efforts but fortunately has overcome many of them. This article outlines the methods the system has used to achieve its minority development goals, with particular emphasis on the difficult area of purchasing.

Hormonal induction of Dopa decarboxylase in the epidermis of Drosophila is mediated by the Broad-Complex

The 2B5 early puff locus corresponds to the Broad-Complex BR-C) and encodes a family of transcription factors whose members are induced by the molting hormone ecdysone. Mutations in the br subcomplementation group substantially reduce the levels of Dopa decarboxylase (DDC) in the epidermis of mature third instar larvae but not in mature second instar organisms. Enzyme levels are normal in the central nervous system of the two mutants examined. The specificity of these effects suggests that a product of the BR-C locus mediates the rapid appearance of DDC in mature third instar larvae experiencing an elevated titer of ecdysone. The likely identity of this protein has been confirmed by pursuing the observation that the br28 allele caused by the insertion of a Pelement into the Z2 DNA-binding domain. Both the transcript and a protein carrying this domain are present in the epidermis and a BR-C recombinant protein carrying the Z2 finger binds to the first intron of the Ddc gene. Five binding sites have been identified within the intron by DNAase I footprinting and a core consensus sequence has been derived which shares some identity with the consensus binding site of the Z2 protein to the Sgs-4 regulatory region. Our demonstration that Ddc is a target of BR-C in the epidermis is the first direct evidence of a role for this early gene in a tissue other than the salivary glands. The data reinforce the idea that BR-C, which clearly mediates a salivary gland-specific response to ecdysone, may play a widespread role in the hormone's activation of gene cascades in other target tissues.

Targeting of an enhancer trap to vestigial

The vestigial gene (vg+) is required for normal wing development and is expressed in a spatially distinct pattern in imaginal discs. We have exploited a general property of P element alleles to target an enhancer trap to the 5' region of the gene. By replacing the P element resident at this site in vg21 with a P element carrying a lacZ reporter gene, the vglacZ1 allele was selected on the basis of its increased mutant phenotype. In contrast to vg+ expression, which occurs primarily in the presumptive wing margin and hinge, beta-galactosidase expression in vglacZ1 wing discs is localized to the dorsal wing surface and displays homologous haltere expression. The targeting of P element enhancer traps could be readily extended to other genes with low rates of primary P element insertion.