Genetic diversity in the endangered Sicilian endemic Brassica rupestris: Proposals for a conservation strategy

Abstract

Brassica rupestris Raf. is a chasmophyte species that includes two subspecies, both endemic to Central-Western Sicily (Italy). Inter-Simple Sequence Repeat (ISSR) markers were used to detect genetic diversity within and among eight populations representative of the species' distribution range. High levels of genetic diversity were revealed both at the population (PPB = 53.88%, H _S = 0.212, Sh = 0.309) and at the species level (PPB = 96.55%, H _T = 0.307, Sh = 0.464). The correlation between genetic and geographical distances was negative (Mantel test, r = ?0.06, P < 0.95). The two subspecies of B. rupestris, subsp. rupestris and subsp. hispida, showed remarkable genetic similarity and molecular data did not unequivocally support their distinctness. The pattern of genetic variation revealed by our study bears important consequences for conservation management: It is desirable to preserve B. rupestris populations in situ with a “dynamic” strategy, while, ex situ conservation programmes might be improved to safeguard maximum genetic diversity.     

Lipid content of terrestrial arthropods in relation to body size,phylogeny, ontogeny and sex

Energy storage in arthropods has important implications for survival and reproduction. The lipid content of 276 species of adult arthropods with wet mass in the range 0.2–6.13 g is determined to assess how lipid mass scales with body mass. The relative contribution of lipids to total body mass is investigated with respect to phylogeny, ontogeny and sex. The lipid content of adult insects, arachnids, and arthropods in general shows an isometric scaling relationship with respect to body mass (M) (M_{arthropod lipid} = ?1.09 ×M_dry^1.01 and M_{arthropod lipid} = ?1.00 ×M_lean^0.98). However, lipid allocation varies between arthropod taxa, as well as with sex and developmental stage within arthropod taxa. Female insects and arachnids generally have higher lipid contents than males, and larval holometabolous insects and juvenile arachnids have higher lipid contents than adults.     

Effect of tower base painting on willow ptarmigan collision rates with wind turbines

1. Birds colliding with turbine rotor blades is a well‐known negative consequence of wind‐power plants. However, there has been far less attention to the risk of birds colliding with the turbine towers, and how to mitigate this risk.
2. Based on data from the Smøla wind‐power plant in Central Norway, it seems highly likely that willow ptarmigan (the only gallinaceous species found on the island) is prone to collide with turbine towers. By employing a BACI‐approach, we tested if painting the lower parts of turbine towers black would reduce the collision risk.
3. Overall, there was a 48% reduction in the number of recorded ptarmigan carcasses per search at painted turbines relative to neighboring control (unpainted) ones, with significant variation both within and between years.
4. Using contrast painting to the turbine towers resulted in significantly reduced number of ptarmigan carcasses found, emphasizing the effectiveness of such a relatively simple mitigation measure.

     

Rechargeable Dual‐Ion Batteries with Graphite as a Cathode: Key Challenges and Opportunities

Rechargeable graphite dual‐ion batteries (GDIBs) have attracted the attention of electrochemists and material scientists in recent years due to their low cost and high‐performance metrics, such as high power density (≈3–175 kW kg^?1), energy efficiency (≈80–90%), long cycling life, and high energy density (up to 200 Wh kg^?1), suited for grid‐level stationary storage of electricity. The key feature of GDIBs is the exploitation of the reversible oxidation of the graphite network with concomitant and highly efficient intercalation/deintercalation of bulky anionic species between graphene layers. In this review, historical and current research aspects of GDIBs are discussed, along with key challenges in their development and practical deployment. Specific emphasis is given to the operational mechanism of GDIBs and to unbiased and correct reporting of theoretical cell‐level energy densities.     

Dissecting the Conformational Dynamics of the Bile Acid Transporter Homologue ASBTNM

Apical sodium-dependent bile acid transporter (ASBT) catalyses uphill transport of bile acids using the electrochemical gradient of Na⁺ as the driving force. The crystal structures of two bacterial homologues ASBT_NM and ASBT_Yf have previously been determined, with the former showing an inward-facing conformation, and the latter adopting an outward-facing conformation accomplished by the substitution of the critical Na⁺-binding residue glutamate-254 with an alanine residue. While the two crystal structures suggested an elevator-like movement to afford alternating access to the substrate binding site, the mechanistic role of Na⁺ and substrate in the conformational isomerization remains unclear. In this study, we utilized site-directed alkylation monitored by in-gel fluorescence (SDAF) to probe the solvent accessibility of the residues lining the substrate permeation pathway of ASBT_NM under different Na⁺ and substrate conditions, and interpreted the conformational states inferred from the crystal structures. Unexpectedly, the crosslinking experiments demonstrated that ASBT_NM is a monomer protein, unlike the other elevator-type transporters, usually forming a homodimer or a homotrimer. The conformational dynamics observed by the biochemical experiments were further validated using DEER measuring the distance between the spin-labelled pairs. Our results revealed that Na⁺ ions shift the conformational equilibrium of ASBT_NM toward the inward-facing state thereby facilitating cytoplasmic uptake of substrate. The current findings provide a novel perspective on the conformational equilibrium of secondary active transporters.     

Promotion by phloroglucinol of micropropagation of Minuartia valentina, an endangered and endemic Spanish plant

Tissue culture techniques for the propagation and conservation of endemic or threatened plants can be used to complement the methods usually applied in ex situ conservation. Thus, Minuartia valentina (Caryophyllaceae), an endangered plant species endemic to the Valencia Community (Eastern Spain), was successfully regenerated through shoot proliferation from wild plants growing in their natural area. Nodal segments, 10~mm long, were cut from rametes of adult material, sterilised and established in vitro. Equally successful shoot multiplication was achieved on Murashige and Skoog (MS) medium with 80 mg l-1 phloroglucinol in combination with either 1 mg l-1 6-benzylaminopurine or 1 mg l-1 kinetin. Excised shoots were rooted in MS medium supplemented with an auxin (indole acetic acid, indole-3-butyric acid, or napththalene acetic acid). Shoots rooted well (96–100%) within three weeks in all auxin treatments. However, the use of napththalene acetic acid was discarded because this auxin delayed root differentiation, and induced adventitious root malformation. Rooted plantlets were transferred to pots and 85% of them acclimatized successfully four weeks after transfer to greenhouse conditions, where they exhibited normal morphology and growth.     

Microsecond Dynamics During the Binding-induced Folding of an Intrinsically Disordered Protein

Tau is an intrinsically disordered protein implicated in many neurodegenerative diseases. The repeat domain fragment of tau, tau-K18, is known to undergo a disorder to order transition in the presence of lipid micelles and vesicles, in which helices form in each of the repeat domains. Here, the mechanism of helical structure formation, induced by a phospholipid mimetic, sodium dodecyl sulfate (SDS) at sub-micellar concentrations, has been studied using multiple biophysical probes. A study of the conformational dynamics of the disordered state, using photoinduced electron transfer coupled to fluorescence correlation spectroscopy (PET-FCS) has indicated the presence of an intermediate state, I, in equilibrium with the unfolded state, U. The cooperative binding of the ligand (L), SDS, to I has been shown to induce the formation of a compact, helical intermediate (IL₅) within the dead time (∼37 µs) of a continuous flow mixer. Quantitative analysis of the PET-FCS data and the ensemble microsecond kinetic data, suggests that the mechanism of induction of helical structure can be described by a U ↔ I ↔ IL₅ ↔ FL₅ mechanism, in which the final helical state, FL₅, forms from IL₅ with a time constant of 50–200 µs. Finally, it has been shown that the helical conformation is an aggregation-competent state that can directly form amyloid fibrils.