Unequal first cleavage is characteristic of a diverse group of protostome animals. In the nematode Caenorhabditis elegans, unequal first cleavage is achieved through the interaction of an apparently symmetric mitotic spindle apparatus with a clearly polarized cell cortex. In the clitellate annelid Tubifex tubifex, by contrast, the spindle is monastral and contains only one gamma-tubulin-reactiv...

Sediment cores conta~ning different dens~t ies of Tubifex tublfex ranging from 0 to 70000 ind m-' were incubated in the laboratory Rates of O2 and NO, uptake NH,' production n~tr~fication and denitnfication were determined from sediment-water fluxes Pore water NH,+was measured at the end of the expenment At natural densities -50000 ind m ', there were increased rates of O2 consumption (x2), den...

We have isolated a Brachyury homologue (Ttu-Bra) from the oligochaete annelid Tubifex tubifex which displays a direct mode of development. Developmental RT-PCR analysis showed that Ttu-Bra transcripts are present in embryos at stages 9-11, 16 and 17, but undetectable at the remaining embryonic stages. Whole-mount in situ hybridization demonstrated that Ttu-Bra is expressed transiently in the th...

A segment of the Guadalquivir River was assessed between Alcalá del Río dam and Seville through an integrative sediment quality assessment. Chemical concentrations metals toxicity under laboratory conditions were used as lines evidence. battery bioassays with four organisms (the amphipod Ampelisca brevicornis, bacteria Vibrio fischeri, sea urchin Paracentrotus lividus, oligochaete Tubifex tubif...