Effect of Exogenous Nitrate on Anaerobic Metabolism in Excised Rice Roots: I. NITRATE REDUCTION AND PYRIDINE NUCLEOTIDE POOLS

Reggiani, R., Brambilla, I. and Bertani, A. 1985. Effect ofexogenous nitrate on anaerobic metabolism in excised rice roots.I. Nitrate reduction and pyridine nucleotide pools.— J.exp.Bot 36:1193-1199. In apical segments of sterile rice roots, reduction of nitratein the absence of oxygen is promoted by the presence of exogenousnitrate in the growth medium in the first 3 h of oxygen deficiency.Anaerobic treatment also increased the concentration of NADH.When nitrate was made available for reduction, smaller accumulationsof NADH were observed. Oxidation of reduced nudeotides associatedwith the conversion of nitrate to nitrite is suggested as beingresponsible for this behaviour. Key words: Anaerobiosis, nitrate, pyridine nucleotides     

Life in harsh environments: carabid and spider trait types and functional diversity on a debris‐covered glacier and along its foreland

1. Patterns of species richness and species assemblage composition of ground‐dwelling arthropods in primary successions along glacier forelands are traditionally described using a taxonomic approach. On the other hand, the functional trait approach could ensure a better characterisation of their colonisation strategies in these types of habitat. 2. The functional trait approach was applied to investigate patterns of functional diversity and life‐history traits of ground beetles and spiders on an alpine debris‐covered glacier and along its forefield in order to describe their colonisation strategies. 3. Ground beetles and spiders were sampled at different successional stages, representing five stages of deglaciation. 4. The results show that the studied glacier hosts ground beetle and spider assemblages that are mainly characterised by the following traits: walking colonisers, ground hunters and small‐sized species. These traits are typical of species living in cold, wet, and gravelly habitats. The diversity of functional traits in spiders increased along the succession, and in both carabids and spiders, life‐history traits follow the ‘addition and persistence model’. Accordingly, there is no turnover but there is an addition of new traits and a variation in their proportion within each species assemblage along the succession. The distribution of ground beetles and spiders along the glacier foreland and on the glacier seems to be driven by dispersal ability and foraging strategy. 5. The proposed functional approach improves knowledge of the adaptive strategies of ground‐dwelling arthropods colonising glacier surfaces and recently deglaciated terrains, which represent landforms quickly changing due to global warming.     

Historical isolation and Quaternary range expansion of divergent lineages in wild grapevine

Vitis vinifera subsp. silvestris, the wild subspecies of Vitis vinifera L., is a unique and valuable genetic resource for cultivated grapevines. At present, this wild form is rare and is spread from the Southern Atlantic coast of Europe to the Western Himalayas. In the present study, six nuclear microsatellite DNAs were analysed in 301 wild grape samples, using factorial correspondence analysis and the Bayesian model. The aim was to detect the distribution of genetic variability and admixture proportions and thus to identify the main routes of recolonization after the quaternary glaciation, as well as signals of secondary contacts in Europe. The results obtained show that some Caucasus and Italian areas played key roles as refugial areas. Moreover, the data suggest the existence of two main migration routes through central Europe during the post‐glacial or the inter‐glacial periods. The first started from Southern Italy and moved northward, whereas the second originated from refugia possibly located in eastern areas and migrated westwards. This scenario is most likely associated with the population expansion that followed the European Quaternary glaciations. In accordance with this assumption, central Europe is proposed as an admixture confluence of migration routes radiating from separate grapevine refugia. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 611–619.     

Effect of Exogenous Nitrate on Anaerobic Metabolism in Excised Rice Roots: II. FERMENTATIVE ACTIVITY AND ADENYLIC ENERGY CHARGE

Reggiani, R., Brambilla, I. and Bertani, A. 1985. Effect ofexogenous nitrate on anaerobic metabolism in excised rice roots.II Fermentative activity and adenylic energy charge.—J.exp. Bot 36: 1698–1704. The presence of nitrate in the culture medium of excised sterilerice roots stimulated CO₂ and ethanol evolution and, to a smallerextent, alanine accumulation. The increased anaerobic carbohydrateconsumption observed in roots grown on nitrate is consistentwith the constantly higher level of adenylic energy charge.An hypothesis serving to explain the evidence concerning theeffect of nitrate on anaerobically grown rice roots is proposed. Key words: Anaerobiosis, ethanol, nitrate, alanine, adenylic energy charge