Many foreign DNAs, such as some virus DNAs and almost all transposable elements (transposons), are capable of integrating host genomes, and the effects of integration can be pleiotropic. To investigate the mechanism and biological effect of foreign DNA insertions, characterization of ...

Vectorette polymerase chain reaction (PCR) is a method designed to amplify DNA when the sequence of one end of the target DNA is unknown (1,2). This technique, therefore, gives a handle on unknown sequence, which flanks DNA that has already been characterized, or sequenced. The vectorette method w ...

The ability of the polymerase chain reaction (PCR) to amplify DNA depends upon the existence of defined primer binding sites. Thus, to amplify a region of flanking unknown DNA sequence, a defined primer binding site must be created. Numerous strategies have been found to do this, such as addition of nu ...

Cells undergoing apoptosis display a number of morphological changes, including chromatin condensation, cytoplasmic shrinkage, membrane blebbing, and the formation of apoptotic bodies (1). These morphological changes are accompanied by structural changes within the cel ...

The epidermal cells, a derivative of ectoderm during embryogenesis of insects, contribute to the distinct cuticular pattern and form of the different stages that appear during their ontogeny. The type of cuticular products is the result of gene expression of the individual epidermal cel ...

The Drosophila wing somatic mutation and recombination test (SMART; also known as the wing spot test) provides a rapid means to assess the potential of a chemical to induce loss of heterozygosity (LOH) resulting from gene mutation, chromosomal rearrangement, chromosome breakage, or chro ...

The imaginal discs of Drosophila melanogaster are saclike clusters of cells that generate the epidermal structures of the adult head, thorax, and external genitalia during metamorphosis. Imaginal disc precursor cells are segregated from larval cells during embryogenesis and fo ...

The central nervous system (CNS) of the third instar larva is a tissue of choice for studying conventional mitotic cycles in Drosophila. For example, squash preparations of the larval CNS are routinely used to investigate chromosome structural and numerical anomalies in late larval leth ...

Drosophila have two basic forms of chromosomes—mitotic and polytene—that have vastly different morphologies and cellular roles. Polytene chromosomes are found in interphase nuclei of differentiated cells, being especially prominent in certain tissues of the larva and adult ov ...

Immunostaining of mitotic chromosomes of larval neuroblasts by antibodies directed against specific proteins is a powerful tool for analyzing their distribution in both euchromatin and heterochromatin. This approach is particularly important for the structural analysis ...

The central nervous system (CNS) of the third instar larva is the most convenient tissue in which to examine both mitotic chromosomes and the diploid interphase nucleus. It contains a mixture of cell types at various degrees of differentiation. Here, methods for examining the diploid nuclei of t ...

The generation of dicentric chromosomes by site-specific recombination is a technique that has been used to study a number of different chromosomal phenomena, including: (1) the segregation of acentric chromosome fragments (1,2), (2) the behavior and resolution of chromosome bridges ...

The cytology of mitotic chromosomes has proved to be essential for research into different aspects of Drosophila biology. Cytological approaches are routinely used to study mutations that affect chromosome behavior or structure. Moreover, cytological methods are essential for ...

Most studies of the structure and function of Dipteran salivary gland poly-tene chromosomes are based on the phenomenon of the relative constancy of the banding pattern characteristic of each species. This made possible the building of cytological maps of polytene chromosomes widely u ...

Polytene chromosomes result from subsequent cycles of DNA replication that are not followed by nuclear division. In Drosophila, this occurs in the majority of larval tissues and is most prominent in salivary glands, where up to eleven rounds of replication events may occur. Because the repli ...

Even with the advent of sequenced genomes, the ability to locate aberration breakpoints onto the salivary chromosome map remains one of the singular strengths of Drosophila as a research organism. Salivary chromosome analysis is not difficult, yet many people are reluctant to attempt to do ...

Acetic orcein staining of polytene chromosomes was introduced in 1941 (1) shortly after the initial studies on aceto-carmine-stained chromosomes by Bridges (2) and has remained a standard method of preparation. Orcein dye can be purchased in both its natural form as extracted from two spec ...

Whole-mount fluorescence in situ hybridization (FISH) to chromosomes of Drosophila embryos is used to pinpoint the position of a chromosomal segment of interest, specified by the DNA probe(s), within a “preserved” three-dimensional nuclear structure. This technique has been used to (1) ...

Double-stranded RNA (dsRNA)-mediated interference, or RNAi, has emerged as an effective technique to phenocopy the loss of function of a given gene product. With this tool researchers can study the functions of individual molecules in living cells and elucidate the mechanisms that regul ...

One of the major foci in cell biology is to understand the process of nuclear division. In each cell cycle, the chromosomes must be faithfully replicated and the complex nuclear structure has to be duplicated and reorganized (1–4). Our understanding of the cell cycle and mitosis has increased dram ...