The respiratory response to heat shock in Neurospora crassa

A sharp decrease in oxygen uptake occurred in Neurospora crassa cells that were transferred from 30 degrees C to 45 degrees C, and the respiration that resumed later at 45 degrees C was cyanide-insensitive. Energization of mitochondria, measured in vivo with fluorescence microscopy and a carbocyanine dye, also declined sharply in cells at 45 degrees C. Electron microscopy showed no changes in mitochondrial complexity; however, the cytoplasm of heat-shocked cells was deficient in glycogen granules.     

Africa goes Europe: The complete phylogeography of the marbled white butterfly species complex Melanargia galathea/M. lachesis (Lepidoptera: Satyridae)

Climatic oscillations influence the distribution of species in time. Thermophilic species survived the ice ages in refugia around the Mediterranean. Northern Africa is one of the possibly important refugia. In this study we test the genetic differentiation between northern African and European populations, using the marbled white butterfly species complex, Melanargia galathea/M. lachesis, as a model. We studied 18 allozyme loci in 876 individuals from 23 populations representing a major part of Europe (northern Spain to Romania) and the western part of northern Africa (Atlas Mountains). The African populations resemble the European ones in allelic richness; their genetic diversity is higher than in Europe. Cluster analysis discriminated five European genetic groups: M. lachesis, a western European lineage, and three eastern European lineages. However, the African samples did not form a separate cluster within this phenogram, but clustered randomly within the Balkan/southeastern European groups. The genetic differentiation among the African populations (F_ST 8.8%) was higher than that within any of the European lineages (F_ST 2.6–5.5%). The high genetic diversity and the relatively strong differentiation of the four African populations sampled in a comparatively limited area of the Atlas Mountains indicate that the most probable origin of M. galathea is northern Africa, with its sibling species, M. lachesis, evolving in parallel in Iberia. Most probably, M. galathea colonised Europe first during the Eem interglacial, some 130 ky ago. Since M. lachesis must have existed on the Iberian peninsula during that period already, M. galathea should have reached Europe via Italy. The genetic differentiation to distinct groups in Europe most probably evolved during the following Würm glacial period.     

Just beautiful?! What determines butterfly species for nature conservation

Prioritization is crucial in nature conservation, as land and financial resources are limited. Selection procedures must follow objective criteria, and not primarily subjective aspects, such as charisma. In this study, we assessed the level of charisma for all European butterflies. Based on these data, we analysed the charisma values of the species listed on the annexes of the EU Habitats Directive and of the species being of conservation priority according to criteria derived by three objective criteria: Species ecological specialisation, distribution, and threat. The mean level of charisma was higher for species of the EU Habitats Directive than for species of conservation priority and for not-listed species. Five of the twenty most charismatic species were also listed on the EU Habitats Directive, but none occurred on the list of species being of conservation priority. A trait space analysis revealed remarkable differences between the different species assortments: The species listed on the EU Habitats Directive covered a large trait space and included many species with high charismatic value, but low ecological and biogeographical relevance, while species of high conservation priority covered a restricted trait space and did not overlap with charismatic species. According to our findings, the selection of species for nature conservation still follows a mix of being aesthetic combined with some ecological criteria.

     

Free radicals act as effectors in the growth inhibition and apoptosis of iron-treated Burkitt's lymphoma cells

The addition of ferric citrate to Burkitt's lymphoma (BL) cell lines inhibits growth, leads to the accumulation of cells in the phase G₂/M of the cell cycle and to the modulation of translocated c-myc expression. The increase in the labile iron pool (LIP) of iron-treated BL cells leads to cytotoxicity. Indeed, intracellular free iron catalyzes the formation of highly reactive compounds such as hydroxyl radicals and nitric oxide (NO) that damages macromolecular components of cells, eventually resulting in apoptosis. In this report, we have investigated the possible involvement of free radicals in the response of Ramos cells to iron. When added to Ramos cells, iron increased the intracellular levels of peroxide/peroxynitrite and NO. Moreover, the addition of free radicals scavengers (TROLOX^® and Carboxy-PTIO) neutralized the effects of iron on Ramos cells while addition of an NO donor or hydrogen peroxide (H₂O₂) to cells generated effects which partially mimicked those induced by iron addition. Collectively, our results suggest the involvement of free radicals as effectors in the iron specific growth inhibition of BL cells observed in vitro.     

Ecosystem functions in natural and anthropogenic ecosystems across the East African coastal forest landscape

Habitat identity and landscape configuration significantly shape species communities and affect ecosystem functions. The conservation of natural ecosystems is of particular relevance in regions where landscapes have already been largely transformed into farmland and where habitats suffer under resource exploitation. The spillover of ecosystem functions from natural ecosystems into farmland may positively influence agricultural productivity and human livelihood quality. We measured three proxies of ecosystem functioning: Pollinator diversity (using pan traps), seed dispersal (with a seed removal experiment), and predation (using dummy caterpillars). We assessed these ecosystem functions in three forest types of the East African dry coastal forest (Brachystegia forest, Cynometra forest, and mixed forest), as well as in adjoining farmland and in plantations of exotic trees (Eucalyptus mainly). We measured ecosystem functions at 20 plots for each habitat type, and along gradients ranging from the forest into farmland. We also recorded various environmental parameters for each study plot. We did not find significant differences of ecosystem functions when combining all proxies assessed, neither among the three natural forest types, nor between natural forest and plantations. However, we found trends for single ecosystem functions. We identified highest pollinator diversity along the forest margin and in farmlands. Vegetation cover and blossom density affected the level of predation positively. Based on our findings, we suggest that flowering gardens around housings and woodlots across farmland areas support ecosystem functioning and thus improve human livelihood quality. We conclude that levels of overall ecosystem functions are affected by entire landscapes, and high landscape heterogeneity, as found in our case, might blur potential negative effects and trends arising from habitat destruction and degradation.     

Influence of acute tryptophan depletion on verbal declarative episodic memory in young adult females

Diminished synthesis of the neurotransmitter serotonin (5-HT) in the brain has been linked to disturbed memory processes. The present study investigated the effects of diminished central nervous 5-HT synthesis as achieved by an acute dietary tryptophan depletion (ATD) on verbal declarative episodic memory in young women while controlling for the effects of female sex hormones. Eighteen healthy females (aged 20–31 years) participated in a within-subject repeated measures study, with two separate days of assessment spaced at least one individual menstrual cycle apart. On one day, participants were subjected to ATD, thus lowering central nervous 5-HT synthesis. The other day participants received a tryptophan-balanced amino acid load (BAL = control condition). The study was randomized, counterbalanced and double blind in terms of ATD/BAL administration. Measurements took place in the early follicular phase of the participants’ menstrual cycle. Estrogen, FSH and LH levels were assessed at baseline. Verbal declarative episodic memory was assessed using a structured word-learning task. Short-term memory, as indexed by immediate recall, was reduced after ATD intake, whereas delayed recall and recognition after a 25-min delay did not show any differences after intake of ATD or BAL. In young women, verbal short-term memory function was more vulnerable to ATD than consolidation processes. In light of the possible interplay between female sex hormones and 5-HT, further studies comparing different menstrual cycle phases are needed.     

Food security versus biodiversity protection: an example of land-sharing from East Africa

The recent controversial debate on land-sharing versus land-sparing is clearly exemplified in the East African mountains, one of the most diverse biodiversity hotspots on our planet. In these areas, species richness is particularly concentrated in the mountain cloud forests which are surrounded by a sea of dry lowland savannas heavily encroached on by local communities. Sustainable land use practices in the lowlands, however, are necessary to safeguard the natural capital at higher elevations. The interdependence between sustainable land-use and conservation of biodiversity hotspots was underlined during a workshop held in the rural areas of Kenya, East Africa, early spring 2013. It was concluded that close links between livelihoods, natural capital and poverty remains a fundamental challenge in East Africa’s forest conservation efforts.     

DCC Expression by Neurons Regulates Synaptic Plasticity in the Adult Brain

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Highlights? DCC and netrin-1 are enriched at synapses in the adult mouse forebrain ? DCC is enriched in the PSD and regulates dendritic spine morphology ? LTP induction and memory formation require DCC expression by neurons ? DCC activation of Src is required for NMDAR-dependent LTP in adult CNS     

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.     

Exploring Sources of Emotional Distress among People Living with Scleroderma: A Focus Group Study

Background

Systemic sclerosis, or scleroderma, is a chronic and rare connective tissue disease with negative physical and psychological implications. Sources of emotional distress and the impact they have on the lives of people with scleroderma are not well understood.

Objectives

To gain an in-depth understanding of the emotional experiences and sources of emotional distress for women and men living with scleroderma through focus group discussions.

Methods

Three semi-structured focus group discussions were conducted (two in English, one in French) with a total of 22 people with scleroderma recruited through the Scleroderma Society of Ontario in Hamilton, Ontario and a scleroderma clinic in Montreal, Canada. Interviews were recorded, transcribed, and then coded for emerging themes using thematic inductive analysis.

Results

Core themes representing sources of emotional distress were identified, including: (a) facing a new reality; (b) the daily struggle of living with scleroderma; (c) handling work, employment and general financial burden; (d) changing family roles; (e) social interactions; and (f) navigating the health care system. Collectively, these themes refer to the stressful journey of living with scleroderma including the obstacles faced and the emotional experiences beginning prior to receiving a diagnosis and continuing throughout the participants’ lives.

Conclusion

Scleroderma was portrayed as being an unpredictable and overwhelming disease, resulting in many individuals experiencing multiple sources of emotional distress. Interventions and supportive resources need to be developed to help individuals with scleroderma and people close to them manage and cope with the emotional aspects of the disease.