Patterns of short-term amino acid accumulation and loss in the root-zone of liquid-cultured forage rape (Brassica napus L.)

Amino acid release from roots of sterile and non-sterile, solution-grown, 7-, 21- and 60-days-old forage rape plants (Brassica napus L.), was measured over periods of up to 6 hours. With sterile plants, release of amino acids into a fixed volume of collection medium (6, 12, 70 mL) was concentration-limited, giving rise to similar convex accumulation profiles for individual acids. In contrast, amino acid accumulation in continuously circulating collection medium was not concentration limited, giving a linear accumulation pattern. The compositions of accumulating amino acids, which were similar to those measured in root extracts, did not change significantly. However, the proportions of ALA, GABA, GLU and ILE in both root extracts and root-derived amino acids increased as plants aged. Older plants released more amino acids per plant, while younger plants released more amino acids g^-1 root DW. Using non-sterile plants, the patterns of change in amino acid concentration and composition in the collection medium were completely different from those determined with sterile plants. In general, with 7-days-old plants, and 60-days-old plants that had recently become non-sterile, an initial rise in the concentration of all acids was followed by a fall to low levels. The loss of amino acids was apparently due to microbial consumption. Individual amino acids attained maximum concentration at different times during the collection process. This is attributed mainly to concentration-dependent differential assimilation of amino acids, since those with the highest initial concentrations, the major components of the mixtures released from roots, declined the earliest. When calculated rates of amino acid release from roots (R_r) and microbial consumption of amino acids (R_c) were compared (for 7-days-old plants), the highest ratios of R_c/R_r were found for ASN, ARG, GLU, GLN, and LYS. This suggests a degree of selectivity for glutamate and nitrogen-rich acids on the part of the consuming micro-organisms. With 21-days old plants and 60-days old plants grown entirely under non-sterile conditions, fluctuations in amino acid concentration were similar for all acids.     

cDNA cloning and expression of a potato (Solanum tuberosum) invertase

A cDNA clone encoding an invertase isoenzyme has been isolated from a potato leaf cDNA library. The deduced amino acid sequence shows significant similarities to previously characterised invertases. The highest degree of overall similarity, including the signal peptide sequence, is to carrot cell wall invertase, suggesting that the potato gene encodes an apoplastic enzyme. Expression of the gene, as determined by RT-PCR, is detected in stem and leaf tissue, and at lower levels in tuber, but is absent from roots.     

Two novel microsatellite markers for prenatal prediction of spinal muscular atrophy (SMA)

Autosomal recessive spinal muscular atrophy (SMA) has been mapped to a 6-cM interval on chromosome 5q12–13.3, flanked proximally by locus D5S6 and distally by locus D5S112. In this study we describe the isolation of two new microsatellite markers (EF1/2a and EF13/14) near locus D5S125, which lies 2 cM distal to D5S6. We show by linkage analysis and the study of the recombinants in 55 SMA pedigrees that the disease lies in the 4-cM interval between EF1/2a and D5S112. Fluorescence in situ analysis of cosmids from D5S6, EF1/2a and D5S112 confirms the genetic order and relative distance of markers. The microsatellites EF1/2a and EF13/14 are the first highly polymorphic PCR based proximal markers in SMA to be described, and will be of value in prental prediction of the disorder.     

Crystallization and preliminary X-ray analysis of nonglycosylated tissue inhibitor of metalloproteinases-1, N30QN78Q TIMP-1

A nonglycosylated (N₃₀QN₇₈Q) form of the human tissue inhibitor of metalloproteinases, TIMP-1, has been prepared and crystallized in a form suitable for X-ray diffraction analysis. Small single crystals have been grown using sodium tartrate as a precipitant. The crystals are in space group P2₁, with cell dimensions a = 35.28, b = 53.95, c = 48.56, and β = 96.0°. There is a single molecule of TIMP-1 in the asymmetric unit. The crystals diffract to at least 2.3 Å resolution. Complete data have been collected to 2.9 Å and a search for heavymetal derivatives is in progress. © 1993 Wiley-Liss, Inc.     

Malignant cerebral glioma--I: Survival,disability, and morbidity after radiotherapy.

OBJECTIVE: To describe survival, disability, and morbidity after radiotherapy for malignant glioma. DESIGN: Two year prospective study with home interviews with patients and relatives. SETTING: Seven neurosurgical and radiotherapy centres in London. SUBJECTS: 105 patients aged 21 to 75: 59 had biopsy; 46 had partial macroscopic resection; 92 received radiotherapy; and 13 received steroids alone. MAIN OUTCOME MEASURES: Survival, time free from disability, and changes in disability after treatment. RESULTS: Six and 12 month survival for radiotherapy patients was 70% and 39%, respectively. Age, World Health Organisation clinical performance status, extent of surgery, and history of seizures before diagnosis each influenced survival. The Medical Research Council prognostic index was also significantly related to survival. Multivariate analysis showed that initial clinical performance status was the most important component of the index. Most (80%; 49/61) patients with a clinical performance status of 0, 1, or 2 lived at least six months before becoming permanently disabled. Most patients who had initially had a good clinical performance status (0-2) and who were alive six months after radiotherapy (68%; 36/52), however, had experienced either clinical deterioration or severe tiredness after treatment. In 17% (9/52) of these some permanent loss of function remained. These adverse effects were associated with increasing radiotherapy dose. Severely disabled patients (clinical performance status 3 or 4) gained little benefit. CONCLUSION: Severely disabled patients gain little physical benefit from radiotherapy, whereas those not so disabled may experience considerable adverse effects.