Characterization of a novel glycine-rich protein from the cell wall of maize silk tissues.

The isolation, characterization and regulation of expression of a maize silk-specific gene is described. zmgrp5 (Zea mays glycine-rich protein 5) encodes a 187 amino acid glycine-rich protein that displays developmentally regulated silk-specific expression. Northern, Western, in situ mRNA hybridization and transient gene expression analyses indicate that zmgrp5 is expressed in silk hair and in cells of the vascular bundle and pollen tube transmitting tissue elements. The protein is secreted into the extracellular matrix and is localized in the cell wall fraction mainly through interactions mediated by covalent disulphide bridges. Taken together, these results suggest that the protein may play a role in maintaining silk structure during development. This is the first documented isolation of a stigma-specific gene from maize, an important agronomic member of the Poaceae family.

The human Hsp70B gene at the HSPA7 locus of chromosome 1 is transcribed but non-functional.

The human heat-inducible Hsp70B and Hsp70B' genes were co-localized to 1q23.1 by in situ hybridization. However, though transcripts from Hsp70B could be detected in heat-shocked cells, DNA sequence analyses of both the gene and cDNA copies of the mRNA indicate the gene is non-functional. Moreover, mouse homologues of Hsp70B/B' were not detected by Southern blot analysis, suggesting Hsp70B/B' arose from either Hsp70-1or Hsp70-2 after the divergence of mice and humans.

Serial propagation of mammalian cells on gelatin-coated microcarriers.

The ability to serially propagate mammalian cells in microcarrier cultures is essential for large-scale operation. The success of such serial propagation depends on viable dissociation of cells from microcarriers and the normal growth and product formation after subsequent reinoculation. The high pH treatment developed for dissociating cells from DEAE-derivatized microcarriers was not as effective for a number of cell strains cultivated on gelatin-coated microcarriers. By prewashing the cell-laden microcarriers with buffer containing a chelating agent, bovine kidney cells, BK, human embryonic foreskin fibroblasts, FS-4, and continuous human kidney cells, TCL-598 which produces prourokinase, were viably dissociated from commercially available gelatin-coated microcarriers, Cytodex-3. Cells dissociated from microcarriers reattached and grew on micro-carriers subsequent to inoculation into subcultures. However, after subculturing, cells may attach at different rates to newly added beads and to conditioned microcarriers which cells had previously grown. It resulted in an uneven cell distribution on microcarriers and inferior growth kinetics. This effect was more profound for BK and FS-4 cells which are propagated with a low multiplication ratio. Specifically, BK cells attach to conditioned beads at a faster rate than to new beads, while FS-4 cells attach to new beads faster than to conditioned beads. Thus, for these two cell strains, a separator was used to separate the microcarriers from the suspension of dissociated cells before subsequent inoculation. For TCL-598 cells, which are propagated at a high multiplication ratio, this dissociation technique can be applied directly without the separation of dissociated cells and conditioned microcarriers. All the three cell lines tested exhibit normal growth kinetics in serial propagation on microcarriers. Furthermore, the production of prourokinase by TCL598 cells serially propagated on microcarriers was comparable to that inoculated from roller bottles.

Dissociation of hepatic messenger ribonucleic acidS14 levels and nuclear transcriptional rates in suckling rats.

The messenger RNA (mRNA) coding for the rat hepatic protein spot 14(S14) (mol wt 17,000; pI 4.9) is rapidly responsive to T3 and carbohydrate administration in the adult animal. In 15-day-old suckling rats, the level of expression is 200-fold less than in 60-day-old chow-fed animals. However, the relative transcriptional activity of the S14 gene is only 30% higher in the 60-day-old rat than in the 15-day-old animal. Although T3 induces a 100-fold increase in mRNAS14 in 15-day-old animals, there was only a 17% increase in the S14 gene transcriptional activity. These results indicate that the hormonal and developmental regulation of the S14 gene in liver appears to be predominantly directed at the posttranscriptional level.

Laser wavelength selection.

The advent of multiwavelength lasers has stimulated considerable interest in wavelength selection, i.e., methods of selecting for various applications one or more of the available wavelengths from a given laser. This paper describes a technique for parallel wavelength separation or recombination of laser beams external to laser cavities. The device used is based on the optical activity of quartz crystals and on the polarization dependent reflection of birefringent calcite crystals.