Polyester Wadding for Specimen Orientation During Embedding in Methacrylates

Polyester fibers are not dissolved by either glycol methacrylate or methyl methacrylate. Commercial polyester wadding is consequently an advantageous material to use in getting precise orientation of tissue specimens during embedding in methacrylate.     

Permanent Preservation of Whole Alizarin Red S Skeletons by Clearing and Embedding in Polyester Resins

A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method.     

Permanent preservation of whole alizarin red S skeletons by clearing and embedding in polyester resins

A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method.     

Chemical accessibility of the 4.5S RNA in spinach chloroplast ribosomes.

We have examined the accessibility to diethylpyrocarbonate of spinach chloroplast 4.5S ribosomal RNA when free and when it is part of the ribosomal structure. The modifications in free 4.5S RNA were found mostly in single-stranded regions of the secondary structure model proposed in our previous paper (Kumagai, I. et al. (1982) J.B.C. 257, 12924-28): adenines at positions 17, 19, 33, 36, 54, 55, 60, 64, 68, 72, 77, 86 and 87 were identified as the reactive residues. On the other hand, in 4.5S RNA in 70S ribosomes or 50S subunits, adenine 33 was exclusively modified, and its reactivity was much higher than in free 4.5S RNA. This highly accessible A33 of spinach 4.5S RNA is located within a characteristic seven nucleotide sequence, which is found in the 4.5S rRNAs from spinach, tobacco and a fern but deleted in 4.5S RNAs from maize and wheat.     

Tryptophan-dependent indoleacetic-acid biosynthesis from indole,demonstrated by double-labelling experiments

Summary ³H-serine+¹⁴C-indole were administered to tips of sterily-grown pea seedlings and of non-sterile oat coleoptiles. The Try and IAA produced were extracted and purified by paper chromatography, and their ³H/¹⁴C ratios were determined. The ³H/¹⁴C ratio of IAA was lower than the ³H/¹⁴C ratio of Try. However, the same decrease of the IAA ³H/¹⁴C ratio was found when ³H, ¹⁴C-Try was supplied instead of ³H-serine+¹⁴C-indole. This result supports the view that Try is the native IAA precursor and that no significant bypass from indole to IAA exists in the plant material used.Abbreviations IAA indole-3-acetic acid - IPyA indole-3-pyruvic acid - Try tryptophan     

IL-1 and IL-4 modulate IL-1 receptor expression in a murine T cell line

The combination of IL-1 and IL-4 stimulates the proliferation of certain murine T cell populations. Although this effect has been best characterized for a number of murine type 2 Th cell (Th2) clones, the mechanism(s) by which these cytokines effect this response is unclear. We have examined the effects of IL-1 and IL-4 on IL-1R expression by MD10 cells, and IL-1-responsive murine T cell line. These cells bear specific IL-1R, which bind human and murine IL-1 alpha and -beta. The measured apparent IL-1R dissociation constant ranged from 41 to 255 pM using 125I-HrIL-1 alpha. Cross-linking studies demonstrated two different 125I-HrIL-1 alpha binding complexes having Mr of 70,000 and 130,000 to 156,000. When removed from passage conditions and placed in non-growth factor-supplemented media, MD10 IL-1R expression spontaneously increased two- to fourfold over the first 11 to 12 h of culture followed by a decline. This phenomenon is partially inhibitable by cycloheximide suggesting that protein synthesis is involved. In agreement with other reports, HrIL-1 alpha down-regulated the expression of its own receptor with an ED50 of between 1 and 10 pM HrIL-1 alpha for this effect. In most experiments, low amounts of HrIL-1 alpha (1.0, 0.1 pM) significantly augmented IL-1R expression. Scatchard analysis of data obtained with all HrIL-1 alpha treatment conditions showed that the effects were due to a change in receptor number, not affinity. Significantly, purified murine IL-4 (MpIL-4) augmented MD10 IL-1R expression in both a time- and dose-dependent fashion. In the presence of 50 U/ml MpIL-4, MD10 IL-1R expression increased two- to threefold after 24 h without a change in receptor affinity. When MpIL-4 (50 U/ml) and various amounts of HrIL-1 alpha (.01-1000 pM) were co-added, the down-regulatory effect of high levels of HrIL-1 alpha was significantly antagonized. When added to cultures after 24 h of HrIL-1 alpha (100 pM) treatment, MpIL-4 reversed the IL-1R down-regulatory effect induced by high levels of HrIL-1 alpha. Finally, when combined in MD10 proliferation assays, MpIL-4 synergistically enhanced the proliferation of MD10 cells treated with suboptimal levels of HrIL-1 alpha.(ABSTRACT TRUNCATED AT 400 WORDS)     

Crystallographic studies of 3-ketoacylCoA thiolase from yeast Saccharomyces cerevisiae

Good diffracting crystals of 3-ketoacylCoA thiolase (EC 2.3.1.16) from yeast Saccharomyces cerevisiae have been obtained. The crystals diffract to at least 2.4 A. The space group of these crystals is P2(1)2(1)2(1), with cell dimensions a = 71.8 A, b = 93.8 A and c = 119.9 A. There is one dimer per asymmetric unit.