The early eukaryotic fossa record

in Advances in Experimental Medicine and Biology (2007), 607

The Precambrian era records the evolution of the domain Eucarya. Although the taxonomy of fossils is often impossible to resolve beyond the level of domain, their morphology and chemistry indicate the ... [more ▼]

The Precambrian era records the evolution of the domain Eucarya. Although the taxonomy of fossils is often impossible to resolve beyond the level of domain, their morphology and chemistry indicate the evolution of major biological innovations. The late Archean record for eukaryotes is limited to trace amounts of biomarkers. Morphological evidence appears in late Paleoproterozoic and early Mesoproterozoic (1800-1300 Ma) rocks. The moderate diversity of preservable eukaryotic organisms includes cell walls without surface ornament (but with complex ultrastructure), with regularly distributed surface ornamentation, and with irregularly or regularly arranged processes. Collectively, these fossils suggest that eukaryotes with flexible membranes and cytoskeletons existed in mid-Proterozoic oceans. The late Mesoproterozoic-early Neoproterozoic (1300-750 Ma) is a time of diversification and evolution when direct evidence for important biological innovations occurs in the fossil record such as multicellularity, sex, photosynthesis, biomineralization, predation, and heterotrophy. Members of extant clades can be recognized and include bangiophyte red algae, xanthophyte algae, cladophorale green algae, euglyphid, lobose, and filose amoebae and possible fungi. In the late Neoproterozoic, besides more diversification of ornamented fossils, florideophyte red algae and brown algae diversify, and animals take the stage. The record of biological innovations documented by the fossils shows that eukaryotes had evolved most cytological and molecular complexities very early in the Proterozoic but environmental conditions delayed their diversification within clades until oxygen level and predation pressure increased significantly. [less ▲]

Reproduction of Lesions and Clinical Signs with a Cnf2-Producing Escherichia Coli in Neonatal Calves

in Advances in Experimental Medicine and Biology (1999), 473

CNF2-producing necrotoxigenic E. coli (NTEC2) are associated with diarrhoea and septicaemia in calves. We orally inoculated neonatal calves with a NTEC2 strain in order to reproduce clinical signs and ... [more ▼]

CNF2-producing necrotoxigenic E. coli (NTEC2) are associated with diarrhoea and septicaemia in calves. We orally inoculated neonatal calves with a NTEC2 strain in order to reproduce clinical signs and lesions. We observed diarrhoea in each inoculated calf, bacteraemia (80%), the presence of CNF2+ bacteria in the lungs (80%) and in the liver (20%). The observed lesions were inflammation of the entire gut, hypertrophy of the mesenteric lymph nodes and hepatisation of the lungs. We were unable to detect characteristic lesions that are classical signs of septicaemia. [less ▲]

Hsv-1 Thymidine Kinase Gene Therapy for Peritoneal Carcinomatosis

in Advances in Experimental Medicine and Biology (1998), 451

Glycoproteins of the aspartyl proteinase gene family secreted by the developing placenta

in Advances in Experimental Medicine and Biology (1995)

Pregnancy in cattle and sheep can be diagnosed by the presence of placentally-derived antigens (pregnancy-associated glycoproteins or PAG-1) in maternal serum soon after implantation begins at about Day ... [more ▼]

Pregnancy in cattle and sheep can be diagnosed by the presence of placentally-derived antigens (pregnancy-associated glycoproteins or PAG-1) in maternal serum soon after implantation begins at about Day 20 following conception. Molecular cloning of their cDNA has revealed that PAG-1 belong to the aspartic proteinase gene family and have about 50% amino acid sequence identity to pepsin. However, critical amino acid substitutions at the active site regions suggest that both bovine and ovine PAG-1 are enzymatically inactive. PAG-1 expression has been shown by in situ hybridization and immunocytochemistry to be localized to the trophoblast binucleate cells, which invade maternal uterine endometrium during implantation. The glycoproteins are concentrated in dense cytoplasmic granules that are discharged after the binucleate cells have migrated to the maternal side of the placental barrier. We suggest, therefore, that the PAG-1 might have an endocrine function either as carriers of other bioactive peptides or by acting as hormones themselves. Recently screening of placental libraries with nucleic acid probes has identified additional cDNA that are very abundant and code for polypeptides (PAG-2 and PAG-3) related to, but antigenically and structurally distinct from PAG-1 described above. These molecules have sequences of amino acids at their catalytic centers that are consistent with their being potentially functional proteinases but their role during pregnancy, like that of PAG-1, is unclear. [less ▲]

Germinal Center T Cells: Analysis of Their Proliferative Capacity

in Advances in Experimental Medicine and Biology (1995), 378

Analysis by in Situ Hybridization of Cytokine Mrnas Expression in Thymic Nurse Cells

in Advances in Experimental Medicine and Biology (1994), 355

Tnf-Alpha Is Involved in the Mechanism of Murine Thymic Lymphoma Prevention by Bone Marrow Grafting

in Advances in Experimental Medicine and Biology (1994), 355

Place of MALT in the immune defence system.

in Advances in Experimental Medicine and Biology (1994), 355

Follicular dendritic cells: isolation procedures, short and long term cultures.

in Advances in Experimental Medicine and Biology (1993), 329

Follicular Dendritic Cells Do Not Produce Tnf-Alpha nor its Receptor

in Advances in Experimental Medicine and Biology (1993), 329