Characterization of transcribed dispersed repetitive DNAs in the nuclear genome of the green alga Chlamydomonas reinhardtii

Abstract

Four cDNAs (cDNAs 1-4), 162, 338, 321 and 167 bp in size, that contain repetitive DNA sequences, were isolated from C. reinhardtii. cDNAs 1, 2 and 3 hybridized to multiple transcripts in poly A+ RNA. Each of the four repeat families is comprised of an extremely heterogeneous population of interspersed nuclear DNA sequences most of which are less than 0.5 kbp in size. A large number of restriction fragment length polymorphisms were uncovered by using cDNAs 1 and 2 as hybridization probes. cDNA2 was compared to two different genomic DNA sequences: the first sequence was complementary to a central 136 bases of cDNA2, which is bordered by a 15-bp imperfect direct repeat; the second sequence lacks a poly-dA tail, but is otherwise colinear along its entire length with cDNA2. This suggests that some members of the cDNA2 repeat family contain signals for polyadenylation. The majority of accumulated transcripts that hybridize to cDNA2 have the same 5'-3' orientation as cDNA2.

Analysis of Chlamydomonas reinhardtii Genome Structure Using Large‐Scale Sequencing of Regions on Linkage Groups I and III

“… b The characterized repeats include Crpl‐4 (Day and Rochaix 1989), Crp5‐8 (P. Ferris, personal communication), the left and right terminus of the Gulliver transposon (Ferris 1989), the left and right terminus of Tcr3 (Wang, Schnell, and Lefebvre 1998), TOC1 (Day et al 1988), TOC2 (Day 1995), and Pioneerl (Graham, Spanier, and Jarvik 1995). …”

“…There are 15 characterized Chlamydomonas repeats. They are Crpl‐4 (Day and Rochaix 3989), Crp5‐8 (P. Ferris, pers. com‐mun.…”

A transposon-like sequence with short terminal inverted repeats in the nuclear genome of Chlamydomonas reinhardtii

“…No significant matches were found between the insertion sequence and DNA sequences in release 41.0 of the EMBL data library. The insertion sequence is also unrelated to TOC1.1 [2] and other dispersed repetitive DNA sequences present in C. reinhardtii [ 1 ]. A 0.48 bp DNA fragment specific for the insertion sequence (Fig.…”

Two GC-rich DNA elements ofChlamydomonas reinhardtii with complex arrangements of directly repeated sequence motifs

“…These GC-rich DNA elements are distinct from other transcribedrepetitiveDNAs foundin C. reinhardtii [3]. In Drosophila, GC-rich sequences appear to be parts of genes whose expression is developmentally regulated [6].…”