Genetic and Molecular Analysis of wings apart-like (wapl), a Gene Controlling Heterochromatin Organization in Drosophila melanogaster

Corresponding author: Maurizio Gatti, Dipartimento di Genetica e Biologia Molecolare, Universitá di Roma “La Sapienza,” Ple. Aldo Moro, 5, 00185 Rome, Italy., gatti{at}axcasp.caspur.it (E-mail)

Communicating editor: R. S. HAWLEY

Mutations in the X-linked gene wings apart-like (wapl) result in late larval lethality associated with an unusual chromosome morphology. In brain cell metaphases of wapl mutants, sister chromatids of all chromosomes are aligned parallel to each other instead of assuming the typical morphology observed in wild type. This effect is due to a loosening of the adhesion between sister chromatids in the heterochromatic regions of the chromosomes. Despite this aberrant chromosome morphology, mutant brains exhibit normal mitotic parameters, suggesting that heterochromatin cohesion is not essential for proper centromere function. On the basis of these observations, we examined the role of wapl in meiotic chromosome segregation in females. wapl exhibits a clear dominant effect on achiasmate segregation, giving further support to the hypothesis that proximal heterochromatin is involved in chromosome pairing during female meiosis. We also examined whether wapl modulates position-effect variegation (PEV). Our analyses showed that wapl is a dominant suppressor of both white and Stubble variegation, while it is a weak enhancer of brown variegation. wapl maps to region 2D of the X chromosome between Pgd and pn. We identified the wapl gene within a previously conducted chromosomal walk in this region. The wapl transcriptional unit gives rise to two alternatively spliced transcripts 6.5- and 5-kb long. The protein encoded by the larger of these transcripts appears to be conserved among higher eukaryotes and contains a tract of acidic amino acids reminiscent of many chromatin-associated proteins, including two [HP1 and SU(VAR)3-7] encoded by other genes that act as suppressors of PEV.

This article has been cited by other articles:

				J.-M. Peters, A. Tedeschi, and J. Schmitz The cohesin complex and its roles in chromosome biology Genes & Dev., November 15, 2008; 22(22): 3089 - 3114. [Abstract] [Full Text] [PDF]

				S. Beisswanger, W. Stephan, and D. De Lorenzo Evidence for a Selective Sweep in the wapl Region of Drosophila melanogaster Genetics, January 1, 2006; 172(1): 265 - 274. [Abstract] [Full Text] [PDF]

				K. J. Dej, C. Ahn, and T. L. Orr-Weaver Mutations in the Drosophila Condensin Subunit dCAP-G: Defining the Role of Condensin for Chromosome Condensation in Mitosis and Gene Expression in Interphase Genetics, October 1, 2004; 168(2): 895 - 906. [Abstract] [Full Text] [PDF]

				K. Oikawa, T. Ohbayashi, T. Kiyono, H. Nishi, K. Isaka, A. Umezawa, M. Kuroda, and K. Mukai Expression of a Novel Human Gene, Human Wings Apart-Like (hWAPL), Is Associated with Cervical Carcinogenesis and Tumor Progression Cancer Res., May 15, 2004; 64(10): 3545 - 3549. [Abstract] [Full Text] [PDF]

				E. S. Belyaeva, L. V. Boldyreva, E. I. Volkova, R. A. Nanayev, A. A. Alekseyenko, and I. F. Zhimulev Effect of the Suppressor of Underreplication (SuUR) Gene on Position-Effect Variegation Silencing in Drosophila melanogaster Genetics, November 1, 2003; 165(3): 1209 - 1220. [Abstract] [Full Text] [PDF]

				T. Westphal and G. Reuter Recombinogenic Effects of Suppressors of Position-Effect Variegation in Drosophila Genetics, February 1, 2002; 160(2): 609 - 621. [Abstract] [Full Text] [PDF]

				K. W. Dobie, C. D. Kennedy, V. M. Velasco, T. L. McGrath, J. Weko, R. W. Patterson, and G. H. Karpen Identification of Chromosome Inheritance Modifiers in Drosophila melanogaster Genetics, April 1, 2001; 157(4): 1623 - 1637. [Abstract] [Full Text]