Ascidians, primitive chordates that have retained features of the likely progenitors to all vertebrates, are a useful model to study the evolutionary relationship of chordates to other animals. We have selected the well characterized ribosomal RNA (rRNA) genes to investigate this relationship, and we describe here the cloning and characterization of an entire ribosomal DNA (rDNA) tandem repeat ...

BACKGROUND Accurate identification of sheep nematodes is a critical point in epidemiological studies and monitoring of drug resistance in flocks. However, due to a close morphological similarity between the eggs and larval stages of many of these nematodes, such identification is not a trivial task. There are a number of studies showing that molecular targets in ribosomal DNA (Internal transcri...

We have determined the nucleotide sequence of part of a cloned ribosomal transcription unit from Xenopus laevis extending from the 3' region of the 18S gene through the 18S-28S intergene region into the start of the 28S gene. The 18S 3' region possess two tracts of high homology with the corresponding segments of other eukaryotic 18S genes (yeast and Bombyx mori) separated by a tract of low hom...

In October 2022, common Asian cowpea (<i>Vigna nakashimae</i>) powdery mildew disease was investigated at Yesan-gun, Chungcheongnam-do, Korea (36°40’12.7"N,126°51’36.4"E). The mainly occurred on the front of leaves, and weak back side leaf. chasmothecia identified Analysis internal transcribed spacer rDNA sequence 28S large subunit sequence, along with morphological characteristics ...

rDNA structure. The nucleus is a highly organized structure. However, unlike cytoplasmic organelles, nuclear substructures are not bounded by membranes, but rather are held together by interactions between their component proteins and nucleic acids, and are thus probably best regarded as giant, extended multi-molecular complexes. The nucleolus is the most prominent of these structures. It is th...

background : in this study, we used both its1 and its2 for molecular identification of fasciola species. methods : the region between 18s and 28s of ribosomal dna was used in pcr-rflp method for molecular identification of fasciola species. ninety trematodes of fasciola were collected during abattoir inspection from livers of naturally infected sheep and cattle from khorasan, east azerbaijan, a...