Some generally accepted viewpoints on the phylogenetic relationships within the molluscan class Gastropoda are reassessed by comparing complete 18S rRNA sequences. Phylogenetic analyses were performed using the neighbor-joining and maximum parsimony methods. The previously suggested basal position of Archaeogastropoda, including Neritimorpha and Vetigastropoda, in the gastropod clade is confirm...

The 18S ribosomal DNA (rDNA) and cytochrome oxidase I region of mitochondrial DNA (mtDNA) were sequenced for 24 Xiphinema americanum-group populations sourced from a number of geographically disparate locations. Sequences were subjected to phylogenetic analysis and compared. 18S rDNA strongly suggested that only X. pachtaicum, X. simile (two populations) and a X. americanum s.l. population from...

The 18S rDNA gene of adult worms of Taenia parva found in Genetta genetta in the Iberian Peninsula and larval stages of T. pisiformis from the wild rabbit (Oryctolagus cuniculus) in Tenerife (Canary Islands) were amplified and sequenced. The sequences of the 18S rDNA gene of T. parva (1768 bp) and T. pisiformis (1760 bp) are reported for the first time (GenBank accession nos. AJ555167-AJ555168 ...

The major mRNA for adenovirus 2 polypeptide pVIII sediments at 18S as assayed by in vitro translation in the messenger-dependent rabbit reticulocyte lysate system. However, a small amount of messenger activity for pVIII sediments at abut 27S, coincident with the mRNA for 100 K. Isolation and fractionation of poly(A) containing RNA following in vitro translation of 27S 100 K mRNA demonstrated th...

The DNA sequence of the intragenic region of the rat 45S ribosomal RNA precursor was determined. This sequence contains 2282 nucleotides and extends from the conserved EcoR I site near the 3' terminus of 18S rRNA to 69 nucleotides downstream of the 5' terminus of 28S rRNA. The sequences corresponding to 18S and 5.8S rRNA were identified by comparison with previously published data. The 5' termi...

Microbial eukaryotes fulfill key ecological positions in marine food webs. Molecular approaches that connect protistan diversity and biogeography to their diverse metabolisms will greatly improve our understanding of marine ecosystem function. The majority of molecular-based studies to date use 18S rRNA gene sequencing to characterize natural microbial assemblages, but this approach does not ne...

Vesicular stomatitis virus messenger RNA has been transcribed in vitro from the viral genome by the virion-associated RNA polymerase in quantities suitable for translation. Wheat germ cell-free extracts programmed with the isolated in vitro 12-18S RNA fraction synthesize polypeptides similar to the viral N, NS, and M proteins, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophores...

Babesiosis is an infectious hemolytic disease that occurs worldwide, and is caused by a protozoan of the Babesia genus (Apicomplexa). Little is known about this genus; therefore, this study conducted a molecular characterization of Babesia spp in naturally infected dogs in northern Brazil. Blood samples were collected from 172 dogs from metropolitan Belém, and screened for Babesia spp using sem...

The large EcoRI fragment of mouse ribosomal genes containing parts of the non-transcribed spacer, the external transcribed spacer located at the 5' end of the precursor molecule and about two thirds of the 18S sequence has been cloned in bacteriophage lambda gtWES. A physical map of the DNA was constructed by cleavage with several restriction endonucleases and hybridization of the restriction ...

Geometric morphometric analyses were conducted on cultured populations of five Micrasterias species (M. crux-melitensis, M. papillifera, M. rotata, M. thomasiana, M. truncata). The patterns in the morphological variation measured using the morphospaces spanned by a PCA of morphometric data for individual populations were compared. In addition, the 18S rDNA sequences of these species are reporte...