High-resolution in situ hybridization and TUNEL staining with free-floating brain sections.

We applied in situ hybridization and the TUNEL technique to free-floating (vibratomed) sections of embryonic and postnatal mouse CNS. Full-length cDNAs specific for oligodendrocyte- or astrocyte-specific genes were labeled with digoxigenin using the random primer method. With paraformaldehyde-fixed sections, the nonradioactive in situ hybridization method provides detection of individual, very small glial progenitor cells in embryonic development. Small, isolated cells expressing oligodendrocyte specific messages can be detected in the neuroepithelium at embryonic and postnatal stages. The technique can be completed within 3 days and is as sensitive as the radioactive method. Likewise, the TUNEL method using DAB as the chromogen on free-floating sections provides excellent resolution. These DAB-stained sections can be embedded in plastic and thin-sectioned to visualize the ultrastructure of apoptotic cells. Both in situ hybridization and TUNEL methods can be applied to the same section, the tissue embedded in plastic, and semithin sections cut. The high resolution obtained with this combined procedure makes it possible to determine whether brain cells expressing glia-specific messages are undergoing apoptosis.     

Erratum to: Rumen-protected conjugated linoleic acid supplementation to dairy cows in late pregnancy and early lactation: effects on milk composition,milk yield,blood metabolites and gene expression in liver

Background  

Conjugated linoleic acid (CLA) is a collective term for isomers of octadecadienoic acid with conjugated double-bond system. Thus, it was the objective to investigate whether milk composition and metabolic key parameters are affected by adding CLA to the diet of dairy cows in the first four weeks of lactation.     

PTC and PROP behave differently in tests of discrimination from their solvents

Better discrimination was possible between phenylthiocarbamide (PTC) solutions and the pure solvent when the solvent was a tasteless low- concentration NaCl solution to which the subject had adapted than when the solvent was purified water. The reverse was true for 6-n- propylthiouracil (PROP). The differences in discrimination for PROP and PTC in the different solvents were caused by differences in the intensity and persistence of aftertastes, rather than a more intense perception of the PTC and PROP tastes per se. This has consequences for traditional approaches to measuring taste sensitivity, as well as indicating that PTC and PROP are not necessarily equivalent indicators of 'taster' versus 'non-taster' status.