Avian remains from the Upper Pleistocene (MIS3) site of Aguilón P-7, south of the Ebro River,Spain

Aves are represented by abundant fossil remains in Quaternary sites. Birds are well adapted to the environment they inhabit, so they make very good paleoenvironmental indicators for Quaternary sites. Here we analyse the avian remains from the Late Pleistocene (probably MIS3) site of Aguilón P-7 (AGP-7). The Pleistocene sediments fill up a shallow cave, which is located in the Zaragozan part of the Iberian Range, 55 km south of the city of Zaragoza. We have for the first time provided a taxonomic and taphonomic study of the avian assemblage of AGP-7, as well as a preliminary paleoenvironmental analysis based on these data. Nine avian taxa have been identified: Galliformes indet., Lagopus sp., Aquila chrysaetos, Gyps fulvus, Passeridae indet., Anthus sp., Prunella modularis,Sturnus cf. unicolor and Corvus monedula. The taphonomic analysis did not provide conclusive information. However, it suggests an accumulation of uneaten food remains by diurnal birds of prey. The identified taxa currently inhabit the Iberian Peninsula, populating woodland environments with rocky areas. They are found in areas with an oceanic climate, in contrast to the Mediterranean climate that now prevails in Aguilón.     

Arabidopsis glt1-T mutant defines a role for NADH-GOGAT in the non-photorespiratory ammonium assimilatory pathway

The physiological role of the NADH-dependent glutamine-2-oxoglutarate aminotransferase (NADH-GOGAT) enzyme was addressed in Arabidopsis using gene expression analysis and by the characterization of a knock-out T-DNA insertion mutant (glt1-T) in the single NADH-GOGAT GLT1 gene. The NADH-GOGAT GLT1 mRNA is expressed at higher levels in roots than in leaves. This expression pattern contrasts with GLU1, the major gene encoding Fd-GOGAT, which is most highly expressed in leaves and is involved in photorespiration. These distinct organ-specific expression patterns suggested a non-redundant physiological role for the NADH-GOGAT and Fd-GOGAT gene products. To test the in vivo function of NADH-GOGAT, we conducted molecular and physiological analysis of the glt1-T mutant, which is null for NADH-GOGAT, as judged by mRNA level and enzyme activity. Metabolic analysis showed that the glt1-T mutant has a specific defect in growth and glutamate biosynthesis when photorespiration was repressed by 1% CO2. Under these conditions, the glt1-T mutant displayed a 20% decrease in growth and a dramatic 70% reduction in glutamate levels. Herein, we discuss the significance of NADH-GOGAT in non-photorespiratory ammonium assimilation and in glutamate synthesis required for plant development.     

Mutagenesis at the ad-3A and ad-3B loci in haploid UV-sensitive strains of Neurospora crassa. IV. Comparison of dose-response curves for MNNG, 4NQO and ICR-170 induced inactivation and mutation-induction

The genetic effects of MNNG, 4NQO and ICR-170 have been compared on 5 different UV-sensitive strains and a standard wild-type strain of Neurospora crassa with regard to inactivation and the induction of forward-mutations at the ad-3A and ad-3B loci. Whereas all UV-sensitive strains (upr-1, uvs-2, uvs-3, uvs-5 and uvs-6) are more sensitive to inactivation by MNNG and ICR-170 than wild-type, only uvs-5 shows survival comparable to wild-type after 4NQO treatment, all other strains are more sensitive to 4NQO. In contrast to the effects on inactivation, a wide variety of effects were found for the induction of ad-3A and ad-3B mutations: higher forward-mutation frequencies than were found in wild-type were obtained after treatment with MNNG or 4NQO for upr-1 and uvs-2, no significant increase over the spontaneous mutation frequency was found with uvs-3 after MNNG, 4NQO or ICR-170 treatment; mutation frequencies comparable to that found in wild-type were obtained with uvs-6 after MNNG, 4NQO or ICR-170 treatment and with upr-1 after ICR-170 treatment. Lower forward-mutation frequencies than were found in wild-type were obtained with uvs-2 after ICR-170 treatment and with uvs-5 after MNNG, 4NQO or ICR-170 treatment. These data clearly show that the process of forward-mutation at the ad-3A and ad-3B loci is under genetic control by mutations at other loci (e.g. upr-1, uvs-2, uvs-3, uvs-5 and uvs-6) and that the effect is markedly mutagen-dependent.     

Laccase activity in melanin-producing strains of Sinorhizobium meliloti

Laccase-like activity was detected in melanin-producing strains of Sinorhizobium meliloti mainly in cells at the stationary growth phase when copper was added to the medium. The laccase showed both syringaldazine and ABTS (2,2'-azino-bis-ethylbenzthiazoline-6-sulfonic acid) oxidase activities and was activated by the addition of 1.7 mM sodium dodecyl sulfate. Activity was totally inhibited by the addition of 1.0 mM EDTA, suggesting that the enzyme is a metal-dependent one. The enzyme was found to be cytosolic having an optimum pH of 5.0, an estimated molecular mass of 95 kDa and a K(m) of 4 microM for syringaldazine. Both laccase and tyrosinase activities were detected in melanin-producing S. meliloti strains. Plant growth-promoting (PGP) effect in rice by a laccase-producing S. meliloti strain when co-inoculated with Azospirillum brasilense Cd was observed. PGP effect by co-inoculation significantly increased plant yield compared to A. brasilense by itself. To the best of our knowledge this is the first report on laccase production in rhizobia and cooperation between Azospirillum and Sinorhizobium in rice.     

Analysis of K-ras and p53 mutations in mesotheliomas from humans and rats exposed to asbestos

Malignant mesothelioma is known to be associated with asbestos exposure. However, the mechanism of mesothelial carcinogenesis in relation to the activation of proto-oncogenes or inactivation of tumor suppressor genes remains unclear. In this study, the PCR-Primer Introduced Restriction Site (PCR-PIRS) assay was employed to examine mutations in the K-ras proto-oncogene in mesothelioma tissues from workers exposed to asbestos and from rats treated with asbestos. Mutations in exons 5-8 of the p53 tumor suppressor gene were determined by direct DNA sequence analysis. Results of the PCR-PIRS analysis revealed no mutations in codons 12, 13 or 61 of the K-ras gene in any of the 17 human or 22 rat mesothelioma tissue samples. These results were confirmed by direct DNA sequence analysis. No mutations were found in exons 5-8 of the p53 gene in any of the mesothelioma tissue samples analyzed. These results and the results reported by others indicate that the K-ras proto-oncogene and p53 tumor suppressor gene may not play a critical role in the induction of mesothelioma by asbestos either in humans or in rats.     

Characterization of an apoplastic basic thaumatin-like protein from recalcitrant chestnut seeds

Mature chestnut seeds, with one of the highest moisture contents described to date, accumulate certain defensive proteins at unusually elevated levels. In this work a major 23-kDa thaumatin-like protein, termed CsTL1, has been purified from mature chestnut ( Castanea sativa ) cotyledons. Amino acid sequencing and characterization of its full-length cDNA indicate that CsTL1 is synthesized as a preprotein with a signal peptide 22 amino acids in length. The mature protein contains 16 conserved cysteine residues presumably involved in disulfide bonding and has a high isoelectric point (ca. 9). Unlike most basic pathogenesis-related (PR) proteins, mature CsTL1 is localized to the extracellular matrix, as revealed by immunoelectron microscopy studies of cotyledonary cells. The isolated protein has in vitro antifungal activity against Trichoderma viride and Fusarium oxysporum and shows strong synergistic effects with CsCh1, the most abundant chestnut cotyledon endochitinase. Moreover, both CsTL1 and CsCh1 appear to be regulated in the same manner during seed development and germination. These observations, along with the recent finding of endoglucanase activity for some TL proteins, support the notion that CsTL1 and CsCh1 are part of a complex seed defensive system against microbial growth. Another possibility is that these, and probably other seed PR proteins, have antifreeze activity. Both functions would be particularly relevant for chestnut seeds given their remarkable moisture content at maturity.     

31P and19F NMR studies of glycophorin-reconstituted membranes: Preferential interaction of glycophorin with phosphatidylserine

Summary Glycophorin A, a major glycoprotein of the erythrocyte membrane, has been incorporated into small unilamellar vesicles composed of a variety of pure and mixed phospholipids. Nuclear spin labels including³¹P and¹⁹F have been used at natural abundance or have been synthetically incorporated in lipids to act as probes of lipid-protein interaction. Interactions produce broadening of resonances in several cases and it can be used to demonstrate preferential interaction of certain lipids with glycophorin.³¹P and¹⁹F probes show a strong preferential interaction of glycophorin with phosphatidylserine over phosphatidylcholine. There is some evidence that interactions are more pronounced at the inner surface of the bilayer and these results are rationalized in terms of the asymmetric distribution of protein and lipid.