High impact information on nullo

• Mutant males produce an excess of XY sperm and nullo sperm, consistent with a high frequency of nondisjunction and/or chromosome loss [1].
• Zygotic expression of the nullo gene is essential for the maintenance of an intact actin-myosin network [2].
• The regulation of nullo RNA levels during cycle 14, however, is coupled to the nucleocytoplasmic ratio, which also controls the cessation of rapid, synchronous mitosis just before cellularization [2].
• The nullo gene encodes a predicted protein of 213 amino acids, a large proportion of which is basic. nullo transcripts are first detectable at nuclear cell cycle 11, peak in accumulation at the end of cycle 13, and disappear rapidly as cellularization begins [2].
• Regulated expression of nullo is required for the formation of distinct apical and basal adherens junctions in the Drosophila blastoderm [3].

Biological context of nullo

• Four 7-13 bp motifs are conserved in the 5' promoter region; two of these are also found, and at the same position relative to the TATA box, in nullo, another zygotic gene recently shown to be involved in cellularisation [4].
• We present new DNA sequence data on the nullo and Serendipity-alpha genes and combine them with all available nuclear DNA sequence data; the total data encompass 12 genes and the ITS of rDNA [5].
• The phenotype of embryonic mosaics is nonautonomous, indicating that nullo does not have to be expressed in every nucleus for proper cellularization [6].
• Examination of nullo mutant clones in adults reveals that nullo activity is not required for cell division in imaginal discs [6].

Anatomical context of nullo

• Zygotic transcription of the nullo and serendipity-alpha genes is required for normal structuring of the microfilament network [7].
• In cellularizing embryos, nullo co-localizes with the actin-myosin network and invaginates along with the leading edge of the plasma membrane [7].

Physical interactions of nullo

• Zygotic activity of the nullo locus is required to stabilize the actin-myosin network during cellularization in Drosophila [6].

Co-localisations of nullo

• The serendipity-alpha (sry-alpha) protein co-localizes with nullo protein to the hexagonal network but, unlike the nullo protein, it localizes to the sides rather than the vertices of each hexagon [7].

Other interactions of nullo

• The compared patterns of expression of D. melanogaster sry alpha and nullo, and D. pseudoobscura sry alpha reveal a complex regulation of the spatiotemporal accumulation of their transcripts [4].

References