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As part of the effort to establish an archeointensity variation curve for Mesoamerica, 13 archeologically well-identified pottery samples belonging to the Ocozocoautla site (Chiapas) were studied. Analyzed samples consist of ‘ofrenda type’ pottery fragments found in several caves. Three archeological intervals are involved: 450-100 B.C., 200–550 A.D. and 550–900 A.D. The Thellier method in its modified form was applied to small fragments previously embedded in salt pellets. Raw intensity values were further corrected for cooling rate effects. The common time-consuming TRM anisotropy correction protocol was substituted by an alternative approach during the paleointensity experiments. Forty-two specimens, belonging to six samples, yielded high-quality Thellier determinations. The NRM fraction fused for paleointensity determination ranges between 0.42 to 0.99, and the quality factor q(Coe et al., 1978) varies from 4 to 59, being normally greater than 5. These results correspond to data of good quality. The mean archeointensity values per pottery fragments range from 14.6±1.5 to 59.5±13.8 μT, while the corresponding virtual axial dipole moments range from 2.5±0.3 to 10.0±2.4 × 1022A m2. These new data, although not numerous, are of high quality and definitively contribute to the Mesoamerican, still insipient, archeointensity database.

The expression of peroxidases (EC 1 11 1 7) during leaf development has been studied by horizontal discontinuous starch-gel electrophoresis in vegetative and flowering plants of Capsicum annuum (var annuum) to assess the nature, subcellular localization and gradients of the peroxidase isoenzymes that characterize the floral state determining the beginning of reproductive development. The results showed that the development of the leaves in both vegetative and flowering plants is accompanied by a significant increase in the level of the peroxidase isoenzyme group prx a, similar to that found along the aging axis of the stem and, therefore, non-organ-specific. An analysis of the subcellular localization of the peroxidase isoenzyme group prx a in flowering plants showed that this isoenzyme group is mainly located bound ionically to cell walls. These results differ from those obtained previously by isoelectric focusing, in which no peroxidase isoenzyme changes were found as a consequence of leaf development. These results, and the fact that ?-mannosidase increases in free spaces of the cell wall as a consequence of leaf development, suggest that the expression of the peroxidase isoenzyme group prx a may be caused by differences in the terminal ?-linked mannose residues of the previously existing peroxidase iso-glycoproteins. Gradients d'isoenzymes des peroxidases dans les feuilles de Capsicuum annuum et leur expression dans les plantes v?g?tatives et en fleurs. L'expression des peroxydases (EC 1 11 17) au cours du d?veloppement a ?t? ?tudi?e par ?lectrophor?se horizontale discontinue sur gel d'amidon chez des plantes ? l'?tat v?g?tatif et ? l'?tat reproducteur de Capsicum annuum (var annuum) pour ?valuer la nature, la localisation subcellulaire et les gradients des enzymes des peroxydases qui caract?risent l'?tat floral d?terminant le d?but du d?veloppement reproducteur. Les r?sultats montrent que le d?veloppement des feuilles est accompagn? tant chez les plantes v?g?tatives que chez celles qui fleurissent par une augmentation significative du groupe d'isoenzymes des peroxydase prx a, qui est analogue ? celui qu'on trouve le long de l'axe de la tige, donc non sp?cifique d'un organe. L'analyse de la localisation subcellulaire du groupe prx a d'isoenzymes des peroxydases chez les plantes fleuries montre que les enzymes de ce groupe sont principalement localis?es sous forme li?e aux parois cellulaires, probablement en ?quilibre avec celles qui circulent librement dans les espaces intercellulaires. Ces r?sultats sont diff?rents de ceux pr?c?demment obtenus par focalisation iso?lectrique, suivant lesquels il n'y avait pas de changement li? au d?veloppement des feuilles. Ces r?sultats, et le fait que la ?-mannosidase augmente dans les espaces intercellulaires, sugg?rent que l'expression des isoenzymes des peroxydases du groupe prx a peut ?tre due ? des diff?rences dans les r?sidus terminaux de mannose en liaison a des iso-glycoprot?ines peroxydases qui pr?-existaient.