Thermodynamic and structural characterization of amino acid-linked dialkyl lipids

Using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), we determined some thermodynamic and structural parameters for a series of amino acid-linked dialkyl lipids containing a glutamic acid-succinate headgroup and di-alkyl chains: C12, C14, C16 and C18 in CHES buffer, pH 10. Upon heating, DSC shows that the C12, C14 and annealed C16 lipids undergo a single transition which XRD shows is from a lamellar, chain ordered subgel phase to a fluid phase. This single transition splits into two transitions for C18, and FTIR shows that the upper main transition is predominantly the melting of the hydrocarbon chains whereas the lower transition involves changes in the headgroup ordering as well as changes in the lateral packing of the chains. For short incubation times at low temperature, the C16 lipid appears to behave like the C18 lipid, but appropriate annealing at low temperatures indicates that its true equilibrium behavior is like the shorter chain lipids. XRD shows that the C12 lipid readily converts into a highly ordered subgel phase upon cooling and suggests a model with untilted, interdigitated chains and an area of 77.2A(2)/4 chains, with a distorted orthorhombic unit subcell, a=9.0A, b=4.3A and beta=92.7 degrees . As the chain length n increases, subgel formation is slowed, but untilted, interdigitated chains prevail.     

An annotated catalogue of salivary gland transcripts in the adult female mosquito, Ædes ægypti*

Background

The number of completely sequenced plastid genomes available is growing rapidly. This array of sequences presents new opportunities to perform comParative analyses. In comParative studies, it is often useful to compare across wide phylogenetic spans and, within angiosperms, to include representatives from basally diverging lineages such as the genomes reported here: Nuphar advena (from a basal-most lineage) and Ranunculus macranthus (a basal eudicot). We report these two new plastid genome sequences and make comparisons (within angiosperms, seed plants, or all photosynthetic lineages) to evaluate features such as the status of ycf15 and ycf68 as protein coding genes, the distribution of simple sequence repeats (SSRs) and longer dispersed repeats (SDR), and patterns of nucleotide composition.

Results

The Nuphar [GenBank:NC_008788] and Ranunculus [GenBank:NC_008796] plastid genomes share characteristics of gene content and organization with many other chloroplast genomes. Like other plastid genomes, these genomes are A+T-rich, except for rRNA and tRNA genes. Detailed comparisons of Nuphar with Nymphaea, another Nymphaeaceae, show that more than two-thirds of these genomes exhibit at least 95% sequence identity and that most SSRs are shared. In broader comparisons, SSRs vary among genomes in s of abundance and length and most contain repeat motifs based on A and T nucleotides.

Conclusion

SSR and SDR abundance varies by genome and, for SSRs, is proportional to genome size. Long SDRs are rare in the genomes assessed. SSRs occur less frequently than predicted and, although the majority of the repeat motifs do include A and T nucleotides, the A+T bias in SSRs is less than that predicted from the underlying genomic nucleotide composition. In codon usage third positions show an A+T bias, however variation in codon usage does not correlate with differences in A+T-richness. Thus, although plastome nucleotide composition shows "A+T richness", an A+T bias is not apparent upon more in-depth analysis, at least in these aspects. The pattern of evolution in the sequences identified as ycf15 and ycf68 is not consistent with them being protein-coding genes. In fact, these regions show no evidence of sequence conservation beyond what is normal for non-coding regions of the IR.     

Ultrasound imaging in an experimental model of fatty liver disease and cirrhosis in rats

Background

Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.

Results

This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.

Conclusions

Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage.     

Combined use of leaf size and economics traits allows direct comparison of hydrophyte and terrestrial herbaceous adaptive strategies

Background and Aims

Hydrophytes generally exhibit highly acquisitive leaf economics. However, a range of growth forms is evident, from small, free-floating and rapidly growing Lemniden to large, broad-leaved Nymphaeiden, denoting variability in adaptive strategies. Traits used to classify adaptive strategies in terrestrial species, such as canopy height, are not applicable to hydrophytes. We hypothesize that hydrophyte leaf size traits and economics exhibit sufficient overlap with terrestrial species to allow a common classification of plant functional types, sensu Grime''s CSR theory.

Methods

Leaf morpho-functional traits were measured for 61 species from 47 water bodies in lowland continental, sub-alpine and alpine bioclimatic zones in southern Europe and compared against the full leaf economics spectrum and leaf size range of terrestrial herbs, and between hydrophyte growth forms.

Key Results

Hydrophytes differed in the ranges and mean values of traits compared with herbs, but principal components analysis (PCA) demonstrated that both groups shared axes of trait variability: PCA1 encompassed size variation (area and mass), and PCA2 ranged from relatively dense, carbon-rich leaves to nitrogen-rich leaves of high specific leaf area (SLA). Most growth forms exhibited trait syndromes directly equivalent to herbs classified as R adapted, although Nymphaeiden ranged between C and SR adaptation.

Conclusions

Our findings support the hypothesis that hydrophyte adaptive strategy variation reflects fundamental trade-offs in economics and size that govern all plants, and that hydrophyte adaptive strategies can be directly compared with terrestrial species by combining leaf economics and size traits.     

SAR study and conformational analysis of a series of novel peptide G protein‐coupled receptor kinase 2 inhibitors

G protein‐coupled receptor kinase 2 (GRK2) plays a central role in the cellular transduction network. In particular, during chronic heart failure GRK2 is upregulated and believed to contribute to disease progression. Thereby, its inhibition offers a potential therapeutic solution to several pathological conditions. In the present study, we performed a SAR study and a NMR conformational analysis of peptides derived from HJ loop of GRK2 and able to selectively inhibit GRK2. From Ala‐scan and d ‐Ala point replacement, we found that Arg residues don't affect the inhibitory properties, while a d ‐amino acid at position 5 is key to the activity. Conformational analysis identified two β‐turns that involve N‐terminal residues, followed by a short extended region. These information can help the design of peptides and peptido‐mimetics with enhanced GRK2 inhibition properties. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 121–128, 2014.     

Essential oils as vespid wasp repellents: Implications for their use as a management strategy

Recently, plant‐based repellents have been proposed as a potential alternative to classic pesticides against pest wasps, in certain scenarios. Here, the repellent effect of Dysphania multifida essential oil and one of its main terpenoid components, α‐terpinene, were tested under field conditions with natural populations of wasps in Patagonia Argentina. D. multifida essential oil (paico), as well as α‐terpinene, repelled V. germanica wasps in the field. A strong avoidance of food baits treated with the essential oil or α‐terpinene was observed in choice and no‐choice tests. In no‐choice tests, the time it took wasps to arrive at the bait was significantly greater in treated baits than in control baits. Also, the total number of arriving wasps in 30 min was significantly greater in untreated baits in comparison with treated baits, under similar environmental conditions and wasp density. As the wasps’ flight season progressed, wasp density and motivation for proteinaceous food sources increased. This was evidenced by a greater total number of wasps in untreated baits with time. On the contrary, the number of wasps in treated baits remained low throughout the peak season. Both the paico essential oil and the α‐terpinene act as powerful repellents for V. germanica wasps, generating an avoidance response to treated food sources. Thus, these compounds have potential to be used as repellents to prevent wasps’ approaches and foraging, when applied in close proximity to a food source.     

A Combination of Fertility Signals and Aggression Regulates Reproduction in the Ant <Emphasis Type="Italic">Gnamptogenys striatula</Emphasis>

Approximately 150 ant species are facultatively or obligately queenless whereby mated workers assume the role of the queen. In many of these species a reproductive dominance hierarchy is established by way of aggressive interactions. Top-ranking workers, which are typically the most fecund, acquire a characteristic cuticular hydrocarbon profile. We studied the temporal dynamics of this chemical change and associated interplay with observed aggressive interactions in an experimentally orphaned colony of the facultatively queenless ant Gnamptogenys striatula. Our observations and chemical analyses demonstrate that chemical fertility signals played a major role in the establishment of a dominance hierarchy and aggression settled dominance relationships only when ants had identical hydrocarbon profiles. Moreover, individuals with a higher potential fertility, in this experiment reflected in a higher ovariole number, are shown to have a better chance of becoming a reproductive.     

Secondary Forests on Anthropogenic Soils of the Middle Madeira River: Valuation,Local Knowledge,and Landscape Domestication in Brazilian Amazonia

Secondary Forests on Anthropogenic Soils of the Middle Madeira River: Valuation, Local Knowledge, and Landscape Domestication in Brazilian Amazonia. Anthropogenic forests and soils are widespread throughout Amazonia and are the product of the landscape domestication process carried out by Amazonian societies since pre-Colombian times. Areas of Terra Preta de índio (TPI, Amazonian Dark Earths) are recognized by local rural residents and associated with specific forms of use and management of these soils and associated secondary forests. We used a quantitative approach to investigate how secondary forests on TPI are recognized and used by local residents along the middle Madeira River, Central Amazonia. Sixty-two residents were interviewed in three riverside communities and listed the ethnospecies and their uses in secondary forests on TPI and on non-anthropogenic soils (NAS). Local residents mentioned more ethnospecies on TPI (mean ± standard deviation: 19.5 ± 8.9) than on NAS (17.4 ± 8.5), and the use value of the environment to the informants (UVia) was higher on TPI (19 ± 5.7) than on NAS (16.2 ± 6.0). Eleven ethnospecies were classified as anthropogenic soil indicators, among which three intensively used palms are widely recognized as indicators of anthropogenic areas and two are domesticated to some degree. The intimate and lasting interactions between humans and TPI have favored the maintenance of secondary forests in these domesticated landscapes with a diverse assemblage of useful and domesticated species. Rural residents in Amazonia recognize these forests as an important source of food and other resources. The use, management, and traditional knowledge related to these domesticated landscapes may provide useful information for the understanding of Amazonian historical ecology and for the design of more efficient biodiversity management and conservation plans.