Epidermal Oxidative Stress in Vitiligo

Epidermal levels of enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), vitamin E (Vit E), ubiquinol (CoQ₁₀H₂), and reduced glutathione (GSH), as well as polyunsaturated fatty acids of phospholipids (PL-PUFA), were evaluated in the affected epidermis of 15 patients with active vitiligo (AVP) and in the corresponding epidermis of 15 healthy phototype matched controls. The epidermal levels of CoQ₁₀H₂, Vit E, GSH, and CAT activity were significantly reduced in AVP and were associated with a marked increase of oxidized glutathione, whereas SODs and GSH-Px activities and ubiquinone concentration remained similar to control values. Antioxidant deficiency, in particular the decline of lipophilic antioxidants, i. e., CoQ₁₀H₂ and Vit E, accounts well for PL-PUFA reduction observed in vitiligo epidermis, mainly affecting C18: 3 n-3, C20: 3 n-6, C20: 4 n-6, and C22: 6 n-3 fatty acids and suggesting the occurrence of a lipoperoxidative process. In conclusion, both an imbalance of the intracellular redox status and a significant depletion of enzymatic and non-enzymatic antioxidants feature the epidermis of AVP, and represent a fingerprint of an abnormal oxidative stress leading to epidermal cell injury.     

Gagea tisoniana, a new species of Gagea Salisb. sect. Gagea (Liliaceae) from central Italy

Gagea tisoniana Peruzzi et al. sp. nov. is described and its taxonomic relationship is discussed. The new species, which appears to be endemic to central Italy, is close to G. pratensis (Pers.) Dumort., G. pusilla (F. W. Schmidt) Sweet, and other mainly poorly known [i.e. G. succedanea Griseb. et Schenk, G. transversalis Stev., and G. paczoskii (Zapal.) Grossh.] or as yet undescribed taxa from eastern Europe and the eastern Mediterranean area. The recognition of the new taxon G. tisoniana is claimed on the basis of anatomical, karyological, ecological, and phytogeographical data. Maps of the Italian distribution of G. pratensis (2 n  = 60), G. pusilla (2 n  = 24), and G. tisoniana (2 n  = 24) are presented, together with an analytical identification key. Finally, G. pratensis is recorded here for the first time in Tuscany (Monte Cetona).  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 337–347.     

Photosynthetic limitations and volatile and non‐volatile isoprenoids in the poikilochlorophyllous resurrection plant Xerophyta humilis during dehydration and rehydration

We investigated the photosynthetic limitations occurring during dehydration and rehydration of Xerophyta humilis, a poikilochlorophyllous resurrection plant, and whether volatile and non‐volatile isoprenoids might be involved in desiccation tolerance. Photosynthesis declined rapidly after dehydration below 85% relative water content (RWC). Raising intercellular CO₂ concentrations during desiccation suggest that the main photosynthetic limitation was photochemical, affecting energy‐dependent RuBP regeneration. Imaging fluorescence confirmed that both the number of photosystem II (PSII) functional reaction centres and their efficiency were impaired under progressive dehydration, and revealed the occurrence of heterogeneous photosynthesis during desiccation, being the basal leaf area more resistant to the stress. Full recovery in photosynthetic parameters occurred on rehydration, confirming that photosynthetic limitations were fully reversible and that no permanent damage occurred. During desiccation, zeaxanthin and lutein increased only when photosynthesis had ceased, implying that these isoprenoids do not directly scavenge reactive oxygen species, but rather protect photosynthetic membranes from damage and consequent denaturation. X. humilis was found to emit isoprene, a volatile isoprenoid that acts as a membrane strengthener in plants. Isoprene emission was stimulated by drought and peaked at 80% RWC. We surmise that isoprene and non‐volatile isoprenoids cooperate in reducing membrane damage in X. humilis, isoprene being effective when desiccation is moderate while non‐volatile isoprenoids operate when water deficit is more extreme.     

Land snail diversity in the monsoon tropics of Northern Australia: revision of the genus Exiligada Iredale, 1939 (Mollusca: Pulmonata: Camaenidae), with description of 13 new species

Vast parts of the monsoon tropics of Australia feature semi‐arid habitats, which are generally thought to harbour a depauperate land snail fauna as compared to the mesic continental fringes, in particular the Australian wet tropics. However, our knowledge of land snails inhabiting these often remote environments is still very patchy. In order to improve the understanding of land snail diversity in the monsoon tropics, we revised the camaenid land snail genus Exiligada based on comprehensive collections, undertaken by use of helicopters on remote limestone outcrops in the Northern Territory and in Western Australia. Based on comparative analyses of shell and genital morphology and patterns of molecular differentiation, we recognize 15 species within Exiligada, 13 of which are newly described. In addition, we suggest a revised delimitation of the type species Exiligada negriensis, as compared to the latest available revision, by removing Exiligada qualis from its synonymy and recognizing it as a distinct species. A key for species identification is also provided. Molecular phylogenetic analyses strongly supported the monophyly of Exiligada with respect to other confamilial genera known to occur in the same geographical region. Most Exiligada species are narrowly endemic to restricted limestone outcrops that cover areas with a diameter of about 20 to 150 km. Within the distributional range of Exiligada, the ranges of up to seven species overlap but we never found more than three species to occur in sympatry at a given sampling site. We propose that species originated by allopatric differentiation, followed by secondary range expansion, leading to sympatric distributions. Our study confirms that less complex rock habitats in more xeric environments support no more than three sympatric species, this being likely to be a result of ecological exclusion. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 689–722.     

Migration distance rather than migration rate explains genetic diversity in human patrilocal groups

In patrilocal groups, females preferentially move to join their mate’s paternal relatives. The gender‐biased gene flow generated by this cultural practice is expected to affect genetic diversity across human populations. Greater female than male migration is predicted to result in a larger decrease in between‐group differentiation for mitochondrial DNA (mtDNA) than for the non‐recombining part of the Y chromosome (NRY). We address the question of how patrilocality affects the distribution of genetic variation in human populations controlling for confounding factors such as ethno‐linguistic heterogeneity and geographic distance which possibly explain the contradictory results observed in previous studies. By combining genetic and bio‐demographic data from Lesotho and Spain, we show that preferential female migration over short distances appears to minimize the impact of a generally higher female migration rate in patrilocal communities, suggesting patrilocality might influence genetic variation only at short ranges.     

The use of low [CO2] to estimate diffusional and non-diffusional limitations of photosynthetic capacity of salt-stressed olive saplings

In this study it has been shown that increased diffusional resistances caused by salt stress may be fully overcome by exposing attached leaves to very low [CO₂] (～ 50 µmol mol^?1), and, thus a non‐destructive‐in vivo method to correctly estimate photosynthetic capacity in stressed plants is reported. Diffusional (i.e. stomatal conductance, g_s, and mesophyll conductance to CO₂, g_m) and biochemical limitations to photosynthesis (A) were measured in two 1‐year‐old Greek olive cultivars (Chalkidikis and Kerkiras) subjected to salt stress by adding 200 mm NaCl to the irrigation water. Two sets of A–C_i curves were measured. A first set of standard A–C_i curves (i.e. without pre‐conditioning plants at low [CO₂]), were generated for salt‐stressed plants. A second set of A–C_i curves were measured, on both control and salt‐stressed plants, after pre‐conditioning leaves at [CO₂] of ～ 50 µmol mol^?1 for about 1.5 h to force stomatal opening. This forced stomata to be wide open, and g_s increased to similar values in control and salt‐stressed plants of both cultivars. After g_s had approached the maximum value, the A–C_i response was again measured. The analysis of the photosynthetic capacity of the salt‐stressed plants based on the standard A–C_i curves, showed low values of the J_max (maximum rate of electron transport) to V_cmax (RuBP‐saturated rate of Rubisco) ratio (1.06), that would implicate a reduced rate of RuBP regeneration, and, thus, a metabolic impairment. However, the analysis of the A–C_i curves made on pre‐conditioned leaves, showed that the estimates of the photosynthetic capacity parameters were much higher than in the standard A–C_i responses. Moreover, these values were similar in magnitude to the average values reported by Wullschleger (Journal of Experimental Botany 44, 907–920, 1993) in a survey of 109 C₃ species. These findings clearly indicates that: (1) salt stress did affect g_s and g_m but not the biochemical capacity to assimilate CO₂ and therefore, in these conditions, the sum of the diffusional resistances set the limit to photosynthesis rates; (2) there was a linear relationship (r² = 0.68) between g_m and g_s, and, thus, changes of g_m can be as fast as those of g_s; (3) the estimates of photosynthetic capacity based on A–C_i curves made without removing diffusional limitations are artificially low and lead to incorrect interpretations of the actual limitations of photosynthesis; and (4) the analysis of the photosynthetic properties in terms of stomatal and non‐stomatal limitations should be replaced by the analysis of diffusional and non‐diffusional limitations of photosynthesis. Finally, the C₃ photosynthesis model parameterization using in vitro‐measured and in vivo‐measured kinetics parameters was compared. Applying the in vivo‐measured Rubisco kinetics parameters resulted in a better parameterization of the photosynthesis model.     

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.