Selection of cell lines resistant to anti-transferrin receptor antibody: evidence for a mutation in transferrin receptor.

Some anti-murine transferrin receptor monoclonal antibodies block iron uptake in mouse cell lines and inhibit cell growth. We report here the selection and characterization of mutant murine lymphoma cell lines which escape this growth inhibition by anti-transferrin receptor antibody. Growth assays and immunoprecipitation of transferrin receptor in hybrids between independently derived mutants or between mutants and antibody-susceptible parental cell lines indicate that all of the selected lines have a similar genetic alteration that is codominantly expressed in hybrids. Anti-transferrin receptor antibodies and transferrin itself still bind to the mutant lines with saturating levels and Kd values very similar to those of the parental lines. However, reciprocal clearing experiments by immunoprecipitation and reciprocal blocking of binding to the cell surface with two anti-transferrin receptor antibodies indicate that the mutant lines have altered a fraction of their transferrin receptors such that the growth-inhibiting antibody no longer binds, whereas another portion of their transferrin receptors is similar to those of the parental lines and binds both antibodies. These results argue that the antibody-selected mutant cell lines are heterozygous in transferrin receptor expression, probably with a mutation in one of the transferrin receptor structural genes.     

Optimization of 19 Rubiaceae species in cell culture for the production of anthraquinones

A total of 19 different species belonging to the genera Asperula, Galium, Rubia and Sherardia were taken into cell culture. All species, differentiated plants as well as tissue cultures, produced anthraquinones in differing yields. Cells were grown in a basal medium containing 7 differently substituted phenoxyacetic acids, as well as 1-naphthaleneacetic acid, all at 10^–5 M concentration. The effectors supporting highest pigment production in each culture were selected and, in the presence of the selected effector, the sucrose content of the medium was then varied from 1 to 14%. Anthraquinone formation was thus optimized for each individual species, but no general pattern, either of effector quality or of sucrose concentration, emerged. In 17 out of 19 cases secondary product formation in optimized cell cultures surpassed that of differentiated plants. The highest anthraquinone yield was observed with Galium verum (1.7 g/l) and the highest concentration achieved with Rubia fruticosa (20% of dry weight).Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - NAA 1-naphthaleneacetic acid - PAA phenoxyacetic acid - dwt dry weight     

Root canal procedure for disarming nonhuman primates.

Nonhuman primates were disarmed by shortening their canine teeth. These teeth were cut off near the gingival level, the entire pulpal tissue removed and the canal filled with a formulated paste which was radiopaque, adhesive and germicidal. The teeth were sealed with a commercial alloy. This endodontic procedure was a quick, practical one-step method for permanently disarming nonhuman primates.     

Fusing VE-Cadherin to α-Catenin Impairs Fetal Liver Hematopoiesis and Lymph but Not Blood Vessel Formation

We have recently shown that genetic replacement of VE-cadherin by a VE-cadherin–α-catenin fusion construct strongly impairs opening of endothelial cell contacts during leukocyte extravasation and induction of vascular permeability in adult mice. Here we show that this mutation leads to lethality at midgestation on a clean C57BL/6 background. Investigating the reasons for embryonic lethality, we observed a lack of fetal liver hematopoiesis and severe lymphedema but no detectable defects in blood vessel formation and remodeling. As for the hematopoiesis defect, VE-cadherin–α-catenin affected neither the generation of hematopoietic stem and progenitor cells (HSPCs) from hemogenic endothelium nor their differentiation into multiple hematopoietic lineages. Instead, HSPCs accumulated in the fetal circulation, suggesting that their entry into the fetal liver was blocked. Edema formation was caused by disturbed lymphatic vessel development. Lymphatic progenitor cells of VE-cadherin–α-catenin-expressing embryos were able to leave the cardinal vein and migrate to the site of the first lymphatic vessel formation, yet subsequently, these cells failed to form large lumenized lymphatic vessels. Thus, stabilizing endothelial cell contacts by a covalent link between VE-cadherin and α-catenin affects recruitment of hematopoietic progenitors into the fetal liver and the development of lymph but not blood vessels.     

Effects of captivity,diet, and relocation on the gut bacterial communities of white‐footed mice

Microbes can have important impacts on their host's survival. Captive breeding programs for endangered species include periods of captivity that can ultimately have an impact on reintroduction success. No study to date has investigated the impacts of captive diet on the gut microbiota during the relocation process of generalist species. This study simulated a captive breeding program with white‐footed mice (Peromyscus leucopus) to describe the variability in gut microbial community structure and composition during captivity and relocation in their natural habitat, and compared it to wild individuals. Mice born in captivity were fed two different diets, a control with dry standardized pellets and a treatment with nonprocessed components that reflect a version of their wild diet that could be provided in captivity. The mice from the two groups were then relocated to their natural habitat. Relocated mice that had the treatment diet had more phylotypes in common with the wild‐host microbiota than mice under the control diet or mice kept in captivity. These results have broad implications for our understanding of microbial community dynamics and the effects of captivity on reintroduced animals, including the potential impact on the survival of endangered species. This study demonstrates that ex situ conservation actions should consider a more holistic perspective of an animal's biology including its microbes.