Regional Amino Acid Concentration in the Brains of Rats Exposed to High Pressures

Regional amino acid concentrations were measured in rat brain fixed by microwave irradiation at three levels of elevated atmospheric pressure corresponding to different phases of the high-pressure neurological syndrome [20 atmospheres absolute (ATA), no clinical signs; 60 ATA, tremor; 85 ATA, severe tremor and myoclonic jerks]. No changes in amino acid content occurred at 20 or 60 ATA. At 85 ATA glutamine content increased in hippocampus, striatum, cerebellum, and substantia nigra, and gamma-aminobutyric acid content increased in hippocampus. It is suggested that enhanced glutamate release in various subcortical structures contributes to the myoclonic activity observed at 85 ATA.     

The response of tomato roots (Lycopersicon esculentum Mill.) to iron deficiency stress: alterations in the pattern of protein synthesis

Dicotyledon plants adapt to iron (Fe) deficiency through a seriesof reactions that increase the ability of the plant to assimilateFe and to increase the efficiency of Fe utilization. In an attemptto gain an insight into these adaptive processes, the specificchanges in protein synthesis associated with the onset of theFe deficiency response in tomato roots (Lycopersicon esculentumMill cv. Rutgers) have been investigated. Roots were grown underFe—sufficient and —deficient conditions, and thepattern of protein synthesis was analysed by in vitro translationof root mRNA and by in vivo labelling of root proteins. Polypeptideswere resolved by two—dimensional polyacrylamide gel elec—trophoresis.Seven polypeptides were identified by in vitro translation,whose synthesis was significantly increased during Fe deficiency.The increase was probably specific to Fe deficiency in thatthe polypep—tide synthesis was not increased during phosphatedeficiency stress, was less prominent following prolonged Fedeficiency and was decreased following re—supply of Feto the hydroponic medium. The pattern of in vitro translation of mRNA isolated from Fe—deficientroots was compared to the results obtainedin vivo followingradiolabelling of proteins. In these analyses, eight polypeptideswere identified, tentatively including the seven polypeptidespreviously identified by in vitro translation. All polypeptideswere characterized with regard to molecular mass and pl andtheir localization in the cell, whether being membrane boundor soluble. It is suggested that members of this group of polypeptidesare involved in the response of the root to Fe deficiency: althoughtheir functions remain to be identified. Key words: In vitro protein synthesis, iron, iron deficiency, root, 2-dimensional PAGE     

Life history patterns of parental and hybrid Daphnia differ between lakes

1. We investigated whether Daphnia galeata × hyalina hybrids of Lake Constance and Lake Greifensee show the same pattern of life history parameters as previously reported for D. galeata × cucullata hybrids and whether such a pattern is consistent between Daphnia populations from those two lakes. 2. Hybrids in Lake Constance were intermediate in size compared with the parental species. Hybrids in Lake Greifensee were smaller than D. galeata. The intrinsic growth rate (r) of hybrids from Lake Constance was not significantly different from the faster growing parental taxon D. galeata. However, r of hybrids from Lake Greifensee was significantly lower than that of D. galeata. 3. The observed juvenile body length differences between the taxa varied with the clutch number. The first clutch juvenile lengths of the three taxa did not differ for Lake Constance. First clutch juveniles of Lake Greifensee D. galeata were smaller than hybrid first clutch juveniles. The third clutch juvenile length did not differ between taxa from Lake Greifensee, but D. galeata juveniles from Lake Constance were bigger than those of D. hyalina. 4. The life history pattern found in Lake Constance corresponds to previous findings from other studies. The hybrids in this lake combine the faster population growth of one parental species with a relatively small size. In the case of Lake Greifensee hybrids, the relatively large size of first clutch juveniles and the small size of the adults could be interpreted as dual adaptations to invertebrate and fish predation. We speculate that the lower population growth rate of the hybrids is a trade‐off for this twofold protection.     

Lysophosphatidic acid is a bioactive mediator in ovarian cancer

Lysophosphatidic acid (LPA) is a naturally occurring phospholipid that exhibits pleiotrophic biological activities, ranging from rapid morphological changes to long-term cellular effects such as induction of gene expression and stimulation of cell proliferation and survival on a wide spectrum of cell types. LPA binds and activates distinct members of the Edg/LP subfamily of G protein-coupled receptors that link to multiple G proteins including Gi, Gq and G12/13 to elicit cellular responses. LPA plays a critical role as a general growth, survival and pro-angiogenic factor, in the regulation of physiological and pathophysiological processes in vivo and in vitro. Our previous work indicates that abnormalities in LPA metabolism and function in ovarian cancer patients may contribute to the initiation and progression of the disease. Thus, LPA could be a potential target for cancer therapy. This review summarizes evidence that implicates LPA in the pathophysiology of human ovarian cancer and likely other types of human malignancies.     

Enlarged processing window of plasticized wheat gluten using salicylic acid

The temperature window for the extrusion of glycerol-plasticized wheat gluten was increased by the use of salicylic acid, a known scorch retarder and radical scavenger. It was possible to extrude 30 wt % glycerol-wheat gluten films with a die-head temperature as high as 135 degrees C, rather than 95 degrees C, by incorporating only 1 wt % salicylic acid. Small effects of shear-induced heating during extrusion at the higher temperatures suggested that the acid acted as a lubricant and viscosity reducer. The latter was suggested to originate primarily from the salicylic-acid-induced reduction in the degree of protein aggregation/cross-linking, as indicated by size-exclusion high-performance liquid chromatography and chemiluminescence. Electron paramagnetic resonance spectroscopy on extruded films indicated that the beneficial effect of salicylic acid was due to its radical scavenging effect. Tensile tests on extrudates revealed that the materials produced at the substantially higher processing temperature were still ductile. The complex shear modulus increased more slowly with increasing salicylic acid content above 110-120 degrees C, indicating that the aggregation/cross-linking rate was slower with salicylic acid, that is, that it did have a scorch-retarding effect, besides yielding a lower final degree/complexity of aggregation.