Caratteristiche della fosfo-gluco-isomerasi di una pianta superiore

Abstract

PHOSPHOGLUCOISOMERASE FROM PEA COTYLEDONS. — 6-P-glucose iso-merase has been purified from pea cotyledons. A 70-fold purification has been obtained by means of acetone fractionation and two absorption-elution steps on calcium phosphate gel. The partially purified enzyme is free of interfering activities.

KM values of 2.5×10^?4 and 10^?4 been measured for glucose-6-P and fructose-6-P respectively. reaction, measured at pH 7.8 and 30° C., is 3.7 (Gl-6-PIFr-6-P).

The enzyme is not inhibited by p-chloro-mercurybenzoate up to 10^?3 M. Besides the substances already known to inhibit competitively the isomerase from animal tissues, the pea enzyme has been found to be competitively inhibited by ribose-5-P and by triosespho-sphates, the K₁, being respectively 7×10^?4 and 2.5×10^?4.

The properties of the pea enzyme are compared to those of animal tissues isomerase. The possible physiological significance of these properties is discussed.     

AZione Della Luce Sull'Assorbimento Salino Da Parte Di Tessuti Clorofilliani In Ambiente Privo Di CO2

Abstract

Effect of light on uptake by photosynthetic tissues in the absence of co₂. — The effect of light and of CO₂ on the uptake of ⁸⁶Rb and ^-32P by isolated leaves of Elodea canadensis has been studied. The uptake of both these ions is strongly stimulated by light both in the presence and in the absence of CO₂. In the case of phosphate, light stimulates uptake and inhibits the leakage of the ion from the tissues.

These results which confirm and extend the results of other Authors, support the conclusion that the stimulation by light of active uptake of solutes by green tissues is physiologically relevant. Furthermore, they suggest that the utilization of light energy for active uptake does not depend on CO₂ fixation and assimilation.     

A Tenebrionid beetle’s dataset (Coleoptera,Tenebrionidae) from Peninsula Valdés (Chubut,?Argentina)

The Natural Protected Area Peninsula Valdés, located in Northeastern Patagonia, is one of the largest conservation units of arid lands in Argentina. Although this area has been in the UNESCO World Heritage List since 1999, it has been continually exposed to sheep grazing and cattle farming for more than a century which have had a negative impact on the local environment. Our aim is to describe the first dataset of tenebrionid beetle species living in Peninsula Valdés and their relationship to sheep grazing. The dataset contains 118 records on 11 species and 198 adult individuals collected. Beetles were collected using pitfall traps in the two major environmental units of Peninsula Valdés, taking into account grazing intensities over a three year time frame from 2005–2007. The Data quality was enhanced following the best practices suggested in the literature during the digitalization and geo-referencing processes. Moreover, identification of specimens and current accurate spelling of scientific names were reviewed. Finally, post-validation processes using DarwinTest software were applied. Specimens have been deposited at Entomological Collection of the Centro Nacional Patagónico (CENPAT-CONICET). The dataset is part of the database of this collection and has been published on the internet through GBIF Integrated Publishing Toolkit (IPT) (http://data.gbif.org/datasets/resource/14669/). Furthermore, it is the first dataset for tenebrionid beetles of arid Patagonia available in GBIF database, and it is the first one based on a previously designed and standardized sampling to assess the interaction between these beetles and grazing in the area. The main purposes of this dataset are to ensure accessibility to data associated with Tenebrionidae specimens from Peninsula Valdés (Chubut, Argentina), also to contribute to GBIF with primary data about Patagonian tenebrionids and finally, to promote the Entomological Collection of Centro Nacional Patagónico (CENPAT-CONICET) and its associated biodiversity data. For these reasons, we believe that this information will certainly be useful for future faunistic, ecological, conservational and biogeographical studies.     

Culture studies on early development of Lessonia trabeculata (Phaeophyceae,Laminariales): Seasonality and acclimation to light and temperature

Lessonia trabeculata is an important economic and ecological algal resource of Chile. Due to intense use in abalone and alginate industries, severe problems of over‐harvesting are emerging. We compared sporophyte‐initiation and ‐growth in two populations from northern and southern Chile (Bahía Inglesa and Maicolpué) under laboratory conditions. Irradiance and temperature were the most important factors affecting gametophyte development. Meiospores harvested in spring exhibited maximum reproductive and growth potential, while spores released during autumn were moribund, and died within a few days. In both study sites, we found evidence for acclimation: Meiospores collected in summer required higher levels of irradiance and temperature for maximum development than winter spores. Juvenile sporophytes from both localities responded similarly to temperature and/or irradiance. The best conditions for recruitment of sporophytes from both localities were 15°C and white fluorescent light of 40–70 μmol m^?2 s^?1. Although due to its low growth potential L. trabeculata is not a good candidate for mariculture, our results provide the necessary knowledge for laboratory‐based seedling production, which is needed for restoration and repopulation projects in damaged areas.