Male MRL/MpJ mice appear to possess an intrinsic ability to 'regenerate' articular cartilage. Understanding the biochemical and genetic basis for articular cartilage regeneration may open up new treatment options for traumatic articular cartilage defects.

2-Methylbutanoate esters, especially ethyl 2-methylbutanoate, are key contributors to fruit aroma. The biosynthetic origins and interconversions of 2-methylbutyl and 2-methylbutanoate esters in Red Delicious and Granny Smith apples were determined by feeding deuterium-labeled substrates with GC-MS identification of the deuterated aroma volatiles produced. Deuterium-labeled isoleucine was fed to apple peel, and 2-methylbutanoic-d 3 acid, 2-methylbutanol-d 3 , and ethyl 2-methylbutanoate-d 3 were fed as vapor to whole apples. An array of labeled 2-methylbutyl and 2-methylbutanoate esters was produced from each substrate with significant differences in products and product distributions between the two apple cultivars. Novel 2-methyl-(2E)-butenyl esters were identified as biosynthetic products in the aroma of Red Delicious but not Granny Smith apples.

Biosynthesis of straight-chain ester volatiles by Granny Smith and Red Delicious apples was investigated using deuterium-labeled fatty acids, C-6 aldehydes, and alcohols. Perdeuterated saturated and monounsaturated fatty acids were metabolized to hexyl-d(11), hexanoate-d(11), heptanoate-d(13), and octanoate-d(15) esters, whereas perdeuterated linoleic acid produced only hexyl-d(11) and hexanoate-d(11) esters. Exposure of fruit to vapors of deuterated 3Z-hexenal, 2E-hexenal, and hexanal identified the following biosynthetic processes: (1) isomerization between 3E, 3Z, and 2E-hexenals; (2) reduction to 3E, 3Z, and 2E-hexenyl esters; (3) reduction to hexanol and hexyl esters; (4) oxidation to hexanoic acid and formation of hexanoate esters; (5) beta-oxidation of hexanoic acid leading to butyl and butanoate esters; and (6) alpha-oxidation of hexanoic acid leading to pentyl and pentanoate esters. Unsaturated straight-chain ester volatiles appear to arise only by the lipoxygenase pathway and may be useful indicators of lipoxygenase activity in fruit.

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Achnatherum inebrians (drunken horse grass) causes symptoms in sheep and horses reminiscent of ergot alkaloid intoxication. Microscopical examination of seed and leaf tissues revealed the presence of an endophytic fungus that did not produce spores when grown in culture and which was serologically related to endophytic Acremonium species of the Albo-lanosa section Morgan-Jones & Gams. ELISA indicated the presence of high concentrations of ergot alkaloids. Ergonovine and lysergic acid amide were identified by HPLCat levels up to 2500 and 400 mg kg-1, respectivelyas the major ergot alkaloids by their retention times and their UV and fluorescence scans. Their identities were confirmed by HPLC analysis of epimerized extracts, and the identity of ergonovine was further confirmed by high-resolution FAB-MS and HPLC−FAB-MS. These are the highest levels of ergonovine and lysergic acid amide so far reported in an endophyte-infected grass, and the similarity of many of the symptoms of A. inebrians intoxication to those previously reported for ergonovine and lysergic acid amide implicates these alkaloids as causative agents of the toxicosis. Endophyte-free A. inebrians did not contain detectable levels of ergot alkaloids and may therefore be useful for stock fodder. A. inebrians was also examined for the presence of other alkaloids that are commonly found in endophyte−grass associations. N-Acetylloline and N-formylloline were not detected by GC, and peramine was not detected by HPLC, in endophyte-infected A. inebrians. However, ELISA and HPLC analyses were consistent with the presence of low levels of analogues of the indole−diterpenoids paxilline and lolitrem B. Keywords: Achnatherum inebrians; Stipa inebrians; Acremonium; endophyte; ergonovine; ergonovinine; lysergic acid amide; isolysergic acid amide

Because ascorbate potentiates chemotaxis of normal leukocytes, we examined the effect of ascorbate on polymorphonuclear leukocytes from a patient with the Chediak-Higashi syndrome. Chemotactic migration was 104+/-16 leukocytes per 10 fields (mean+/-S.D.) initially and 258+/-44 (P less than 0.001) after ascorbate, as compared to 182+/-10 in controls. There was no bactericidal activity by 40 minutes in the patient's untreated leukocytes. After ascorbate bactericidal activity of patient and untreated control cells was the same. The addition of ascorbate reduced cAMP levels in the patient's cells from a mean of 34.5 pmoles per 10(7) polymorphonuclear leukocytes to 5.9, as compared to a control value of 3.1+/-1.4. The association of elevated cAMP and impaired function in the polymorphonuclear leukocytes of patients with the Chediak-Higashi syndrome may be related to abnormal microtubular assembly.

It is a long-held belief in evolutionary biology that the rate of molecular evolution for a given DNA sequence is inversely related to the level of functional constraint. This belief holds true for the protein-coding homeotic (Hox) genes originally discovered in Drosophila melanogaster. Expression of the Hox genes in Drosophila embryos is essential for body patterning and is controlled by an extensive array of cis-regulatory modules (CRMs). How the regulatory modules functionally evolve in different species is not clear. A comparison of the CRMs for the Abdominal-B gene from different Drosophila species reveals relatively low levels of overall sequence conservation. However, embryonic enhancer CRMs from other Drosophila species direct transgenic reporter gene expression in the same spatial and temporal patterns during development as their D. melanogaster orthologs. Bioinformatic analysis reveals the presence of short conserved sequences within defined CRMs, representing gap and pair-rule transcription factor binding sites. One predicted binding site for the gap transcription factor KRUPPEL in the IAB5 CRM was found to be altered in Superabdominal (Sab) mutations. In Sab mutant flies, the third abdominal segment is transformed into a copy of the fifth abdominal segment. A model for KRUPPEL-mediated repression at this binding site is presented. These findings challenge our current understanding of the relationship between sequence evolution at the molecular level and functional activity of a CRM. While the overall sequence conservation at Drosophila CRMs is not distinctive from neighboring genomic regions, functionally critical transcription factor binding sites within embryonic enhancer CRMs are highly conserved. These results have implications for understanding mechanisms of gene expression during embryonic development, enhancer function, and the molecular evolution of eukaryotic regulatory modules.

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