Singlet oxygen scavenging activity of tocopherol and plastochromanol in Arabidopsis thaliana: relevance to photooxidative stress

In the present study, singlet oxygen (¹O₂) scavenging activity of tocopherol and plastochromanol was examined in tocopherol cyclase‐deficient mutant (vte1) of Arabidopsis thaliana lacking both tocopherol and plastochromanol. It is demonstrated here that suppression of tocopherol and plastochromanol synthesis in chloroplasts isolated from vte1 Arabidopsis plants enhanced ¹O₂ formation under high light illumination as monitored by electron paramagnetic resonance spin‐trapping spectroscopy. The exposure of vte1 Arabidopsis plants to high light resulted in the formation of secondary lipid peroxidation product malondialdehyde as determined by high‐pressure liquid chromatography. Furthermore, it is shown here that the imaging of ultra‐weak photon emission known to reflect oxidation of lipids was unambiguously higher in vte1 Arabidopsis plants. Our results indicate that tocopherol and plastochromanol act as efficient ¹O₂ scavengers and protect effectively lipids against photooxidative damage in Arabidopsis plants.     

VIRTUE ETHICS AND THE SELECTION OF CHILDREN WITH IMPAIRMENTS: A REPLY TO ROSALIND MCDOUGALL

In ‘Parental Virtues: A New Way of Thinking about the Morality of Reproductive Actions’ Rosalind McDougall proposes a virtue‐based framework to assess the morality of child selection. Applying the virtue‐based account to the selection of children with impairments does not lead, according to McDougall, to an unequivocal answer to the morality of selecting impaired children. In ‘Impairment, Flourishing, and the Moral Nature of Parenthood,’ she also applies the virtue‐based account to the discussion of child selection, and claims that couples with an impairment are morally justified in selecting a child with the same impairment. This claim, she maintains, reveals that the flourishing of a child should be understood as requiring environment‐specific characteristics. I argue that McDougall's argument begs the question. More importantly, it does not do justice to virtue ethics. I also question to what extent a virtue ethics framework can be successfully applied to discussions about the moral permissibility of reproductive actions.     

Hydroxy‐plastochromanol and plastoquinone‐C as singlet oxygen products during photo‐oxidative stress in Arabidopsis

In the present study, we have shown that hydroxy‐plastochromanol and plastoquinone‐C, the hydroxy derivatives of plastochromanol and plastoquinone‐9, respectively, are specifically formed from the parent compounds upon action of singlet oxygen and can be regarded as stable, specific, natural products of singlet oxygen action during photo‐oxidative stress in vivo. The presented data indicate that plastoquinone‐C formation dominates mainly during relatively short periods of high light stress where efficient production of singlet oxygen takes place, whereas hydroxy‐plastochromanol is rather formed under conditions of long‐term, less pronounced generation of singlet oxygen. An interesting observation was that hydroxy‐plastochromanol is formed even at very low light conditions (5–10 μmol photons m^?2 s^?1), indicating that singlet oxygen is generated not only during high light stress but also its formation by photosystem II is inseparably connected with the functioning of this photosystem even at the lowest light intensities.     

Feeding response of the stable fly, Stomoxys calcitrant L., to blood fractions and adenine nucleotides

Abstract Feeding responses of the stable fly ( Stomoxys calcitrans L., Diptera: Muscidae) to blood fractions and saline-based diets were studied in an artificial feeding device. Flies fed equally on whole blood, plasma and erythrocyte fractions while resuspended platelets or the buffy layer did not stimulate feeding. Evidence from filtration studies indicates that plasma contains both less-than-5000D and greater-than-100,000D phagostimulatory components. ATP, ADP and AMP in saline stimulate feeding in this insect in a dose-dependent manner. cAMP also stimulates feeding in the range of concentrations tested. It is argued that the less-than-5000D phagostimulant may be one or more of these adenine nucleotides.     

Beetle species’ responses suggest that microclimate mediates fragmentation effects in tropical Australian rainforest

Abstract Despite the enormous contribution of invertebrates to global biodiversity and ecosystem function, the patterns and causes of insect responses to tropical rainforest destruction and fragmentation remain poorly understood. We studied the responses of beetles to these factors in a fragmented upland rainforest landscape in north‐east Queensland, Australia. Beetles were sampled using flight interception traps from six replicate sites in rainforest interior, rainforest edge, small rainforest remnants and pasture, interspersed across about 600 km². Beetles from 10 family/subfamily groups were sorted to species. There were three major findings. First, converting rainforest into pasture has a very strong negative effect on beetle diversity and species composition. Very few beetle species were present in pasture and none of the most abundant species was more abundant in pasture than rainforest. Second, beetle assemblages appeared to respond to climate. Beetle species composition in drier rainforest habitats was different from that of moister rainforest and there were species unique to each rainforest type. Third, beetle species composition differed between small remnants and interior rainforest: drier‐associated species were more abundant in small remnants, whereas wetter‐associated species were more abundant in interiors. Edges tended to be intermediate. We argue that this pattern can be attributed to a fragmentation effect mediated by differences in microclimate rather than by floristic, structural, or area and isolation effects.     

A morphological classification capturing functional variation in phytoplankton

1. A logical way of distinguishing functional groups of phytoplankton is to cluster species according to their functional traits, such as growth rate and nutrient assimilation constants. However, data for such an approach are lacking for the vast majority of the species. 2. In this study, we show that a classification based on simple morphological traits may capture much of the variability in functional properties among the phytoplankton. We used information on more than 700 freshwater species, from more than 200 lakes situated in climate zones ranging from subpolar to tropical. 3. Morphological characteristics correlated well with functional properties, such as growth rate and sinking rate, and also with the population size and biomass attained in the field. This suggests that morphology is a good predictor of the functional characteristics of species. 4. Cluster analysis was used to define seven species groups based on morphology. Although some of the clusters are taxonomically homogeneous, others include species of several separate divisions. Functional traits (not used for the classification) differed significantly among the clusters, suggesting that the clusters may indeed represent meaningful functional groups. 5. Advantages of our morphological approach to classification include its objectivity, its independence from taxonomic affiliations, and the relative ease of its application to the majority of species for which physiological traits are unknown and are not readily determined.     

Cladistic analysis of Omalodini Kryzhanovskij (Coleoptera: Histeridae: Histerinae)

According to the current Histeridae classification, Omalodini is composed of 100 species described in 12 genera distributed in the Neotropical, Afrotropical, Afrotemperate and Oriental regions: Asolenus Lewis; Atribalus Bickhardt; Blypotehus Vienna, Ebonius Lewis; Lewisister Bickhardt; Notolister Lewis; Omalodes Erichson, divided in Omalodes (Omalodes), O. (Diplogrammicus) Lewis and O. (Cornillus) Lewis; Perfidolenus Vienna; Rhypochares Marseul; Scapomegas Lacordaire; Sphyracus Marseul; Theropatina Mazur. Our aims were to test the monophyly of Omalodini, using cladistic analysis, and propose a hypothesis of the phylogeny of the tribe. The matrix was composed of 49 terminal taxa (34 from the ingroup and 15 from the outgroup) and 131 characters of the adult morphology. The data were analysed under equal weights and implied weights. In both analyses, Omalodini represents a polyphyletic group and the trees obtained from equal weights analysis (two most parsimonious trees) were chosen in order to recover the tribe's monophyly. We recognize three lineages in Omalodini: Ebonius, undescribed genus and Omalodes, being supported by six transformations (Ebonius + (undescribed genus + Omalodes)). The sister group of Omalodini was defined as a clade composed of Histerini, Platysomatini and Hololeptini. The subgenera of Omalodes were not resolved consistently under different implied weight analyses. It is necessary to emphasize that Omalodes (Omalodes) comprises the largest group of Omalodini and requires an analysis with better sampling for more precise resolution of the internal phylogeny of the genus. The groups excluded a posteriori from Omalodini, Theropatina, Asolenus, Atribalus, Blypotehus, Lewisister, Notolister, Perfidolenus, Rhypochares, Sphyracus and Scapomegas, could not be allocated to any of the existing tribes of Histerinae.