We report the isolation, by RT‐PCR, of partial cDNAs encoding the rat peroxisome proliferator‐activated receptor (PPAR) isoforms PPARα, PPARβ, and PPARγ and the rat retinoid X receptor (RXR) isoforms RXRα, RXRβ, and RXRγ. These cDNAs were used to generate antisense RNA probes to permit analysis, by the highly sensitive and discriminatory RNase protection assay, of the corresponding mRNAs in rat brain regions during development. PPARα, PPARβ, RXRα, and RXRβ mRNAs are ubiquitously present in different brain regions during development, PPARγ mRNA is essentially undetectable, and RXRγ mRNA is principally localised to cortex. We demonstrate, for the first time, the presence of PPAR and RXR mRNAs in primary cultures of neonatal meningeal fibroblasts, cerebellar granule neurons (CGNs), and cortical and cerebellar astrocytes and in primary cultures of adult cortical astrocytes. PPARα, PPARβ, RXRα, and RXRβ mRNAs are present in all cell types, albeit that PPARα and RXRα mRNAs are at levels near the limit of detection in CGNs. PPARγ mRNA is expressed at low levels in most cell types but is present at levels similar to those of PPARα mRNA in adult astrocytes. RXRγ mRNA is present either at low levels, or below the level of detection of the assay, for all cell types studied.

A small number of cellular proteins accumulate to high levels in cells infected with Herpes Simplex Virus (HSV) despite a generalised repression of most host cell bio-synthesis. An antibody to one such protein has been used to screen a lambda gt11 library and for polysome immunoprecipitation in order to isolate cDNA clones derived from the corresponding gene. The cDNA clones have been used in dot blot and nuclear run-off assays to show that HSV, like other DNA tumour viruses can transcriptionally induce a cellular gene. The mechanism of this effect which is dependent on viral protein synthesis and its possible significance in transformation by HSV are discussed.

Treating kraft pulps with the crude xylanase from Streptomyces roseiscleroticus followed by alkali extraction reduces the kappa number in a linear manner with enzyme doses up to about 3 IU/gm of oven-dry pulp. The enzyme complex consists of four isoenzymes designated Xyll, Xyl2, Xyl3 and Xyl4. Each can release chromophores when used alone and each can facilitate alkali extraction to reduce the kappa number, but their relative abilities are different. Of the four isozymes, Xyl4 releases the least color and 237-nm-absorbing material whereas Xyl3 releases the most. Xyl4 best enhances the ability of alkali to reduce the kappa number. The UV absorption spectrum of the material released by alkali extraction differs significantly from the spectral characteristics of that released during enzyme treatment. The alkali-solubilized material has a maximum absorptivity at 265 nm and relatively little absorptivity at 237 nm. The material released during enzyme treatment • absorbs strongly at 205 and 237 nm. UV/VIS spectroscopy of the enzyme-or alkali-released material does not show a characteristic lignin peak at 280 nm, nor does it reveal any notable peaks in the visible region. Analysis of the material released by enzyme treatment revealed more than 40 product peaks after fractionation by reversed-phase HPLC. We observed many products with strong UV absorption. These were relatively hydrophilic. Fewer products absorbed in the visible region. These were more hydrophobic. All four isoenzymes exhibit endo-action patterns; none forms xylose from oatspelt xylan. The action patterns fell into two groups: endo-1 enzymes (Xyll and Xyl3) formed xylotriose (X3) and other lower oligosaccharides as the predominant products; endo-2 enzymes (Xyl2 and Xyl4)formed roughly equimolar amounts of X3, xylotetraose (X4), and xylopentaose (Xs), and tended to leave larger amounts of undigested higher oligosaccharides.

Streptomyces roseiscleroticus produces extracellular xylanases when cultured on a liquid xylan medium. Purified xylanases are used to facilitate bleaching of kraft pulps in the pulp and paper industry. Downstream processing and purification of xylanases from S. roseiscleroticus is difficult unless red pigments produced by the bacterium are removed. We report that the bioprocessing agent, Biocryl BPA-1000, removes these pigments allowing purification of four xylanases by HPLC employing cation exchange, hydrophobic interaction, and gel filtration. The xylanases have been named Xyl1, Xyl2, Xyl3, and Xyl4 according to their order of elution from the cation exchange column. The purified xylanases have been characterized according to their molecular weights, pH and temperature stabilities, N-terminal amino acid sequences, and hydrolysis action patterns on oat spelt xylan. The molecular weights by mass spectroscopy for Xyl1-Xyl4 are 33,647, 33,655, 21,070, and 46,855, respectively. All four xylanases exhibit pH optima between 5.0 and 7.0 and temperature optima between 50 and 60 degrees C. The N-terminal amino acid sequences are compared to sequences from Streptomyces lividans, Streptomyces 36A, and a Chainia sp. The N-terminal amino acid sequence of Xyl1 appears to be unique, but sequences from Xyl2, 3, and 4 bear strong homology to xylanases cloned from S. lividans. Xyl3 is also homologous to xylanases from Streptomyces 36A, and a Chainia sp. Predominant products of arabinoxylan hydrolysis by the purified xylanases included xylotriose, tetraose, and pentaose. None of the xylanases purified from S. roseiscleroticus produced xylose.

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