Evolution of the transposable element Uhu in five species of Hawaiian Drosophila

ABSTRACT The I-R element at the R locus destabilizes kernel pigmentation giving the variegated pattern known as stippled (R-st). In trans linkage phase with R-st the element was shown to act as a modifier of stippled, intensifying seed spotting in parallel with effects of the dominant linked modifier M-st. Presence of I-R in the genome was, therefore, shown to be detectable as a modifier of R-st. When this test was used, new modifiers resembling M-st were often detected following mutations of R-st to the stable allele R-sc. Such mutations evidently occurred by transposition of I-R away from the R locus to a site where it was identifiable as a modifier. M-st may be such a transposed I-R. Analysis of mutations to R-sc during the second (sperm-forming) mitosis in pollen grains showed that some of the transposed I-R elements were linked with R, whereas others assorted independently. Their strengths varied from barely discernible to a level equal to M-st. Overreplication frequently accompanied transposition at the sperm-forming mitosis, leading to transposed I-R elements in both the mutant and nonmutant sperm.

Download Full-text

hobo enhancer trapping mutagenesis in Drosophila reveals an insertion specificity different from P elements.

Genetics ◽

10.1093/genetics/135.4.1063 ◽

1993 ◽

Vol 135 (4) ◽

pp. 1063-1076 ◽

Cited By ~ 2

Author(s):

D Smith ◽

J Wohlgemuth ◽

B R Calvi ◽

I Franklin ◽

W M Gelbart

Keyword(s):

Drosophila Melanogaster ◽

Transposable Element ◽

Enhancer Trap ◽

P Element ◽

Present Evidence ◽

P Elements ◽

Element Insertion ◽

Enhancer Trapping ◽

Indispensable Tool

Abstract P element enhancer trapping has become an indispensable tool in the analysis of the Drosophila melanogaster genome. However, there is great variation in the mutability of loci by these elements such that some loci are relatively refractory to insertion. We have developed the hobo transposable element for use in enhancer trapping and we describe the results of a hobo enhancer trap screen. In addition, we present evidence that a hobo enhancer trap element has a pattern of insertion into the genome that is different from the distribution of P elements in the available database. Hence, hobo insertion may facilitate access to genes resistant to P element insertion.

Download Full-text

CHROMOSOMAL SEQUENCES AND INTERISLAND COLONIZATIONS IN HAWAIIAN DROSOPHILA

Genetics ◽

10.1093/genetics/103.3.465 ◽

1983 ◽

Vol 103 (3) ◽

pp. 465-482

Author(s):

Hampton L Carson

Keyword(s):

Polytene Chromosomes ◽

Complex Species ◽

Hawaiian Drosophila ◽

On This Island ◽

Break Points ◽

Chromosomal Sequences ◽

Founder Events ◽

Paracentric Inversions ◽

Single Set

ABSTRACT Of 103 picture-winged Drosophila species endemic to the high Hawaiian islands, all but three are endemic to single islands or island complexes. They are presumed to have evolved in situ on each island. The banding pattern sequences of the five major polytene chromosomes of these species have been mapped to a single set of Standard sequences. Sequential variation among these chromosomes is due to 213 paracentric inversions. An atlas of their break points is provided. Geographical, morphological and behavioral data may be used to supplement the cytological information in tracing ancestry. Starting at the newer end of the archipelago, the 26 species of the Island of Hawaii (less than 700,000 years old) are inferred to have been derived from 19 founders, 15 from the Maui complex, three from Oahu and one from Kauai. The existence of 40 Maui complex species is explicable as resulting from 12 founders, ten from Oahu and two from Kauai. The 29 Oahu species can be explained by 12 founder events, five from Kauai and seven from Maui complex (summary in Figure 5). Although the ancestry of two Kauai species can be traced to newer islands, the ten remaining ones on this island (age about 5.6 million years) are apparently ancient elements in the fauna, relating ultimately to Palearctic continental sources.

Download Full-text

Arabidopsis MORC proteins function in the efficient establishment of RNA directed DNA methylation

Nature Communications ◽

10.1038/s41467-021-24553-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yan Xue ◽

Zhenhui Zhong ◽

C. Jake Harris ◽

Javier Gallego-Bartolomé ◽

Ming Wang ◽

...

Keyword(s):

Dna Methylation ◽

Arabidopsis Thaliana ◽

Transposable Element ◽

Zinc Finger ◽

Protein Function ◽

C Elegans ◽

Eukaryotic Organisms

AbstractThe Microrchidia (MORC) family of ATPases are required for transposable element (TE) silencing and heterochromatin condensation in plants and animals, and C. elegans MORC-1 has been shown to topologically entrap and condense DNA. In Arabidopsis thaliana, mutation of MORCs has been shown to reactivate silent methylated genes and transposons and to decondense heterochromatic chromocenters, despite only minor changes in the maintenance of DNA methylation. Here we provide the first evidence localizing Arabidopsis MORC proteins to specific regions of chromatin and find that MORC4 and MORC7 are closely co-localized with sites of RNA-directed DNA methylation (RdDM). We further show that MORC7, when tethered to DNA by an artificial zinc finger, can facilitate the establishment of RdDM. Finally, we show that MORCs are required for the efficient RdDM mediated establishment of DNA methylation and silencing of a newly integrated FWA transgene, even though morc mutations have no effect on the maintenance of preexisting methylation at the endogenous FWA gene. We propose that MORCs function as a molecular tether in RdDM complexes to reinforce RdDM activity for methylation establishment. These findings have implications for MORC protein function in a variety of other eukaryotic organisms.

Download Full-text