Several cytogenetic markers show chromosomal diversity in the fish such as "armoured catfish". Although studies have characterized many species in the major genera representing these Siluridae, particularly in the genus Hypostomus Lacépède, 1803, trends in chromosome evolution of this group remain unclear. The Paraíba do Sul river basin contains the armoured catfish Hypostomus affinis Steindach...

We have sequenced one complete rDNA tandem repeat from the nematode C. elegans. By comparative analysis we derive secondary structures for the 18s, 5.8s, and 26s rRNA molecules, and comment on other important features of the sequence. We also present the sequence of a junction between the rDNA and non-ribosomal DNA. Finally, we use our data to quantify the evolutionary relationships among sever...

BACKGROUND Because many picoplanktonic eukaryotic species cannot currently be maintained in culture, direct sequencing of PCR-amplified 18S ribosomal gene DNA fragments from filtered sea-water has been successfully used to investigate the astounding diversity of these organisms. The recognition of many novel planktonic organisms is thus based solely on their 18S rDNA sequence. However, a specie...

A parasitological study carried out in May 2022 and March 2023 the Nyando River of Lake Victoria Basin, Kenya, disclosed two parasitic lernaeid copepods: Lamproglena cleopatra Humes, 1957, from gills a cyprinid, Ningu Labeo victorianus Boulenger, 1901, endemic to drainage system, clariae Fryer, clariid, North African catfish Clarias gariepinus (Burchell, 1822). The copepods were studied supplem...