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Biomedical subjects

F Jotereau

Publications and source records attributed to F Jotereau.

42 records · Page 3Linked to original sources
PubMed1987

Relationship between thymus ontogeny and DNA ligase expression in the chicken.

DNA ligase expression was studied in the embryonic chicken thymus. As previously reported, during thymus ontogeny two separate and successive (8S and 6S) forms of enzyme are found. The switch from the heavy to the light form takes place at around 18 days of incubation in situ. The demonstration that two successive generations of thymic lymphoid precursor cells develop in the embryonic bird thymus and that the replacement of the first by the second thymocyte generation takes place at around 18 days suggested the possibility that each form of enzyme could be restricted to a given thymocyte generation. By either culturing or transplanting embryonic thymuses of different ages it appears that the switch from the heavy to the light form of DNA ligase is not related to a change over of the first by the second generation of embryonic thymocytes but rather to some maturation process of the thymic lymphocytes starting from 17 days of embryonic life. The influence of extrathymic factors on the turning on of the expression of the 6 S DNA ligase in the post-natal environment is also suggested.

Animals↗
PubMed1987

Cytogenetics of Abelson virus-induced malignant lymphoma cell lines in the mouse.

Cytogenetic studies were performed on 11 established murine thymoma or peripheral lymphoma cell lines induced by a thymotropic Abelson virus. In eight cell lines a trisomy 5 was present, whereas, two cell lines had a normal karyotype like fresh tumor cells. In the last cell line a trisomy 11 resulting from a t(5;11) was observed. The origin of this nonrandom chromosome abnormality is briefly discussed.

Abelson murine leukemia virus↗
PubMed1985

Relationships between terminal transferase expression, stem cell colonization, and thymic maturation in the avian embryo: studies in thymic chimeras resulting from homospecific and heterospecific grafts.

Terminal deoxynucleotidyl transferase (TdT) can be detected in 11- to 12-day-old embryonic chick thymuses 5 to 6 days after the first influx of lymphoid stem cells into the thymic rudiment. To identify the main factors of TdT induction, grafting experiments were devised in such a way that the age of the grafted thymus and that of the host were different. Uncolonized embryonic chick thymuses were grafted into chick hosts of different ages. Under these conditions, lymphoid differentiation arose from host lymphoid stem cells (LSC) invading the thymic rudiment. TdT immunofluorescent detection in the first wave of thymocytes showed that the percentages of TdT+ cells were related to the total age of the explant and not to the age of the host (11 to 17 days). Similar results were obtained when the chick thymic rudiment was transplanted into quail embryos, showing that quail LSC have TdT inducibility similar to that of chick LSC while developing in a chick thymic environment. Colonized chick thymuses were also grafted into quail embryos to compare the TdT inducibility of the first lymphoid generation (of chick type) and of the second (of quail origin), taking advantage of the different chromatin structure of quail and chick cells. In these experiments, the majority of chick cells remained TdT negative for as long as 10 days, whereas most lymphocytes of the second generation became TdT+ soon after their arrival in the grafted thymus. Therefore, during embryonic life, most TdT+ cells were derived from the second wave of stem cells, but some early stem cells were also able to acquire the enzyme. In a final series of experiments, early thymic rudiments were cultured in vitro with 14- to 16-day-old bone marrow and then grafted into 3-day-old host embryos. Under these conditions, bone marrow LSC contributed to a variable proportion of the first generation of thymocytes. The percentage of TdT+ cells among the progeny of these bone marrow stem cells was found to be two times higher than that of thymocytes derived from host LSC. These results suggest that, in addition to intrathymic environmental factors, the origin of LSC influences the frequency of TdT expression in their progeny.

Animals↗
PubMed1985

[Origin of osteoclasts].

The haematogenous origin of osteoclasts has been demonstrated in recent years by the use of cellular markers in experiments in early bone grafts in bird embryos and the transfer of haematopoietic cells in the osteoporotic mammals. The nature of the mononuclear precursor(s) of the osteoclasts has not been determined. Studies currently underway demonstrate that relatively immature cells present in the bone marrow of adults and in various embryonic haematopoietic organs, as well as blood monocytes are capable of participating in osteoclastic differentiation in various animal models.

Animals↗