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41.
42.
Sara Bobone Gianfranco Bocchinfuso Yoonkyung Park Antonio Palleschi Kyung‐Soo Hahm Lorenzo Stella 《Journal of peptide science》2013,19(12):758-769
Antimicrobial peptides (AMPs) are promising compounds for developing new antibiotic drugs against drug‐resistant bacteria. Many of them kill bacteria by perturbing their membranes but exhibit no significant toxicity towards eukaryotic cells. The identification of the features responsible for this selectivity is essential for their pharmacological development. AMPs exhibit few conserved features, but a statistical analysis of an AMP sequence database indicated that many α‐helical AMPs surprisingly have a helix‐breaking Pro residue in the middle of their sequence. To discriminate among the different possible hypotheses for the functional role of this feature, we designed an analogue of the antimicrobial peptide P5, in which the central Pro was deleted (analogue P5Del). Pro removal resulted in a dramatic increase of toxicity. This was explained by the observation that P5Del binds both charged and neutral membranes, whereas P5 has no appreciable affinity towards neutral bilayers. CD and simulative data provided a rationalization of this behavior. In solution P5, due to the presence of Pro, attains compact conformations, in which its apolar residues are partially shielded from the solvent, whereas P5Del is more helical. These structural differences reduce the hydrophobic driving force for association of P5 to neutral membranes, whereas its binding to anionic bilayers can still take place because of electrostatic attraction. After membrane binding, the Pro residue does not preclude the attainment of a membrane‐active amphiphilic helical conformation. These findings shed light on the role of Pro residues in the selectivity of AMPs and provide hints for the design of new, highly selective compounds. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
43.
Juri Battilana Silvia Lorenzi Flavia M. Moreira Paula Moreno-Sanz Osvaldo Failla Francesco Emanuelli M. Stella Grando 《Molecular biotechnology》2013,54(3):1031-1037
Cultivars used for wine and table grape have self-fertile hermaphrodite flowers whereas wild European vines and American and Asian species are dioecious, having either male or female flowers. Consistent with previous studies, the flower sex trait was mapped as a single major locus on chromosome 2 based on a pure Vitis vinifera population segregating for hermaphrodite and female progeny, and a hybrid population producing all three flower sex types. The sex locus was placed between the same SSR and SNP markers on both genetic maps, although abnormal segregation hampered to fine map the genomic region. From a total of 55 possible haplotypes inferred for three SSR markers around the sex locus, in a population of 132 V. sylvestris accessions and 171 V. vinifera cultivars, one of them accounted for 66 % of the hermaphrodite individuals and may be the result of domestication. Specific size variants of the VVIB23 microsatellite sequence within the 3′-UTR of a putative YABBY1 gene were found to be statistically significantly associated with the sex alleles M, H and f; these markers can provide assistance in defining the status of wild grapevine germplasm. 相似文献
44.
The East Aegean (East Aegean Islands, Greece and West Anatolia, Turkey) is a biogeographically transitional region, where biodiversity elements from Europe and Asia join. However, affinities in the region were until recently scarcely explored. We assess biogeographical affinities in the East Aegean focusing on distribution patterns of Lamiaceae plants in Chios Island and its adjacent Çe?me–Karaburun Peninsula. Detailed in-situ record was acquired for 48 native species. These were grouped based on their habitat and geological substrate preference, their distribution was mapped in grid cells and distribution patterns were analysed in relation to species groupings. In both Chios and Çe?me–Karaburun, species follow five distribution patterns: widespread, locally widespread, locally restricted, sporadic and rare. Fifty to 62% of the species exhibit similar distribution patterns, trends in habitat and geological substrate preference in Chios and Çe?me–Karaburun, results complying with previous evidence of close biogeographical affinities of the East Aegean Islands and neighbouring Anatolia. Differences observed between the two regions may be attributed to insularity effects, human impact and the melange, an old rock matrix known for its key role in elucidating regional geodynamic evolution. Distributions of widespread and locally widespread species in Chios give evidence of density compensation and niche shifts responses, however, the actual occurrence of these phenomena in island plant populations is still to be elucidated. Overall, the species distribution patterns, particularly those of rare ones, reflect the complex geological history, palaeogeography and human influence in the Aegean region. 相似文献
45.
Stella Manta Vanessa Parmenopoulou Christos Kiritsis Athina Dimopoulou Nikolaos Kollatos Ioannis Papasotiriou 《Nucleosides, nucleotides & nucleic acids》2013,32(7):522-535
This article describes the synthesis of (3 ′S) and (3 ′R)-3 ′-amino-3 ′-deoxy pyranonucleosides and their precursors (3 ′S) and (3 ′R)-3 ′-azido-3 ′-deoxy pyranonucleosides. Azidation of 1,2:5,6-di-O-isopropylidene-3-O-toluenesulfonyl-α-D-allofuranose followed by hydrolysis and subsequent acetylation afforded 3-azido-3-deoxy-1,2,4,6-tetra-O-acetyl-D-glucopyranose, which upon coupling with the proper silylated bases, deacetylation, and catalytic hydrogenation, obtained the target 3 ′-amino-3 ′-deoxy-β-D-glucopyranonucleosides. The desired 1-(3 ′-amino-3 ′-deoxy-β-D-allopyranosyl)5-fluorouracil was readily prepared from the suitable imidazylate sugar after azidation followed by a protection/deprotection sequence and reduction of the unprotected azido precursor. No antiviral activity was observed for the novel nucleosides. Moderate cytostatic activity was recorded for the 5-fluorouracil derivatives. 相似文献
46.
47.
Background
In various species mating exerts direct and indirect effects on female demographic traits ranging from life span shortening to behavioural shifts. A wealth of data regarding effects of nutrition on longevity and reproduction output also exists. Nonetheless, little is known regarding the interaction between the age of mating and nutrition on female fitness.Methodology
We studied, the effects of protein deprivation and age of mating on female fitness traits, using a wild population of the Mediterranean fruit fly (medfly). We tested the hypotheses that (a) protein availability increases female lifespan and fecundity, (b) female longevity and egg production are independent of mating and the age of mating, and (c) female mating behaviour is independent of their age and nutritional status. Thus, we recorded the mating success and the copulation characteristics, as well as the egg production and survival of females mated at young or at old age and fed a full or a protein-deprived diet.Results
Mating boosts egg production and reduces longevity of protein-fed females. On the contrary, mating increases the longevity of protein-deprived females. Mortality responses (negative or positive) to mating are expressed after a long lag phase. Old females are more receptive and less selective than young females regardless of the food regime.Conclusions
Our findings suggest that condition (nutritional status and age) defines the positive or negative output of mating in female medflies. These results contribute towards understanding the effects of mating, aging, resource allocation and their interactions on survival and female reproduction. 相似文献48.
49.
Robert Bronstein Luisa Torres Jillian C. Nissen Stella E. Tsirka 《Journal of visualized experiments : JoVE》2013,(78)
Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and pathological processes such as CNS maturation in development, multiple sclerosis, and spinal cord injury. Microglia can be activated and recruited to action by neuronal injury or stimulation, such as axonal damage seen in MS or ischemic brain trauma resulting from stroke. These immunocompetent members of the CNS are also thought to have roles in synaptic plasticity under non-pathological conditions. We employ protocols for culturing microglia from the neonatal and adult tissues that are aimed to maximize the viable cell numbers while minimizing confounding variables, such as the presence of other CNS cell types and cell culture debris. We utilize large and easily discernable CNS components (e.g. cortex, spinal cord segments), which makes the entire process feasible and reproducible. The use of adult cells is a suitable alternative to the use of neonatal brain microglia, as many pathologies studied mainly affect the postnatal spinal cord. These culture systems are also useful for directly testing the effect of compounds that may either inhibit or promote microglial activation. Since microglial activation can shape the outcomes of disease in the adult CNS, there is a need for in vitro systems in which neonatal and adult microglia can be cultured and studied. 相似文献
50.
Hui Chen Alisha Dorrigan Sonia Saad Dominic J. Hare Michael B. Cortie Stella M. Valenzuela 《PloS one》2013,8(2)