Extracellular lipid droplets promote hemozoin crystallization in the gut of the blood fluke Schistosoma mansoni

Hemozoin (Hz) is a heme crystal produced upon hemoglobin digestion as the main mechanism of heme disposal in several hematophagous organisms. Here, we show that, in the helminth Schistosoma mansoni, Hz formation occurs in extracellular lipid droplets (LDs). Transmission electron microscopy of adult worms revealed the presence of numerous electron-lucent round structures similar to LDs in gut lumen, where multicrystalline Hz assemblies were found associated to their surfaces. Female regurgitates promoted Hz formation in vitro in reactions partially inhibited by boiling. Fractionation of regurgitates showed that Hz crystallization activity was essentially concentrated on lower density fractions, which have small amounts of pre-formed Hz crystals, suggesting that hydrophilic-hydrophobic interfaces, and not Hz itself, play a key catalytic role in Hz formation in S. mansoni. Thus, these data demonstrate that LDs present in the gut lumen of S. mansoni support Hz formation possibly by allowing association of heme to the lipid-water interface of these structures.     

Toward molecular dissection of PrPC-PrPSc interactions

Direct interaction between endogenous cellular prion protein (PrP(C)) and misfolded, disease-associated (PrP(Sc)) conformers is a key event in prion propagation, which precedes templated conversion of PrP(C) into nascent PrP(Sc) and prion infectivity. Although almost none of the molecular details of this pivotal process are understood, the persistence of individual prion strains suggests that assembly of the prion replicative complex is mechanistically precise. To systematically map defined regions of PrP(C) sequence that bind tightly to PrP(Sc), we have generated a comprehensive panel of over 45 motif-grafted antibodies containing overlapping peptide grafts collectively spanning PrP residues 19-231. Grafted antibody binding experiments, performed under stringent conditions, clearly identified only three distinct and independent high affinity PrP(Sc) recognition motifs. The first of these binding motifs lies at the very N-terminal region of the mature PrP molecule within PrP-(23-33); the second motif lies within PrP-(98-110); and the third is contained within PrP-(136-158). Mutational analyses of these PrP(Sc)-binding regions revealed that reactivity of the 23-33 and 98-110 segments are largely dependent upon the presence of multiple positively charged amino acid residues. These studies yield new insight into critical peptidic components composing one side of the prion replicative interface.     

Short allele of serotonin transporter gene promoter is a risk factor for obesity in adolescents

Obesity and hypertension are increasing medical problems in adolescents. Serotonin transporter (5-HTT) is involved in mood and eating disturbances. Encoded by the gene SLC6A4, the promoter shows functional insertion/deletion alleles: long (L) and short (S). Because individuals who are carriers for the short version are known to be at risk for higher levels of anxiety, we hypothesized that this variant may be associated with overweight. Data and blood samples were collected from 172 adolescents out of a cross-sectional, population-based study of 934 high school students. To replicate the findings, we also included 119 outpatients from the Nutrition and Diabetes Section of the Children's County Hospital. We found that the S allele was associated with overweight (BMI > 85th percentile), being a risk factor for overweight independently of sex, age, and hypertension [odds ratio (OR): 1.85; 95% confidence interval (CI): 1.13, 3.05; p < 0.02]. Additionally, in the outpatient study, compared with the homozygous LL subjects, S allele carriers showed a higher BMI z-score (1.47 +/- 1.09 vs. 0.51 +/- 1.4; p < 0.002) and were more frequent in overweight children. In conclusion, the S allele of the SLC6A4 promoter variant is associated with overweight being an independent genetic risk factor for obesity.     

New 2,6,9-trisubstituted adenines as adenosine receptor antagonists: a preliminary SAR profile

A new series of 2,6,9-trisubstituted adenines (5–14) have been prepared and evaluated in radioligand binding studies for their affinity at the human A₁, A_2A and A₃ adenosine receptors and in adenylyl cyclase experiments for their potency at the human A_2B subtype. From this preliminary study the conclusion can be drawn that introduction of bulky chains at the N ⁶ position of 9-propyladenine significantly increased binding affinity at the human A₁ and A₃ adenosine receptors, while the presence of a chlorine atom at the 2 position resulted in a not univocal effect, depending on the receptor subtype and/or on the substituent present in the N ⁶ position. However, in all cases, the presence in the 2 position of a chlorine atom favoured the interaction with the A_2A subtype. These results demonstrated that, although the synthesized compounds were found to be quite inactive at the human A_2B subtype, adenine is a useful template for further development of simplified adenosine receptor antagonists with distinct receptor selectivity profiles.     

Identification andin silico characterisation of putative conjugative transfer genes onGeobacillus stearothermophilus plasmids

We repor the first data demonstrating the presence of putative conjugative transfer genes on plasmids of the speciesGeobacillus stearothermophilus. Partial sequence analysis of the plasmid pGS18 fromG. stearothermophilus 18 was determined. It contained eleven complete open reading frames. Five of them encoded proteins which are homologous toBacillus megaterium pBM300 Mob/TraA,Lactococcus lactis pMRC01 TrsD and TrsE,Staphylococcus aureus pGO1 TrsG andS. aureus subsp.aureus pUSA03 TraL, the proteins that are associated with conjugative plasmid transfer. Southern hybridizations were performed on two other plasmids isolated fromG. stearothermophilus 3 andG. stearothermophilus 19 strains using the most homologous parts of those five genes as probes. Data from different hybridization patterns show a close homology of putative conjugative transfer genes between pGS18 and pGS3 hypothesizing a similar molecular organization of putative conjugative plasmid transfer region of both plasmids.     

Independently evolving species in asexual bdelloid rotifers

Asexuals are an important test case for theories of why species exist. If asexual clades displayed the same pattern of discrete variation as sexual clades, this would challenge the traditional view that sex is necessary for diversification into species. However, critical evidence has been lacking: all putative examples have involved organisms with recent or ongoing histories of recombination and have relied on visual interpretation of patterns of genetic and phenotypic variation rather than on formal tests of alternative evolutionary scenarios. Here we show that a classic asexual clade, the bdelloid rotifers, has diversified into distinct evolutionary species. Intensive sampling of the genus Rotaria reveals the presence of well-separated genetic clusters indicative of independent evolution. Moreover, combined genetic and morphological analyses reveal divergent selection in feeding morphology, indicative of niche divergence. Some of the morphologically coherent groups experiencing divergent selection contain several genetic clusters, in common with findings of cryptic species in sexual organisms. Our results show that the main causes of speciation in sexual organisms, population isolation and divergent selection, have the same qualitative effects in an asexual clade. The study also demonstrates how combined molecular and morphological analyses can shed new light on the evolutionary nature of species.     

Insect pest management in the age of synthetic biology

Arthropod crop pests are responsible for 20% of global annual crop losses, a figure predicted to increase in a changing climate where the ranges of numerous species are projected to expand. At the same time, many insect species are beneficial, acting as pollinators and predators of pest species. For thousands of years, humans have used increasingly sophisticated chemical formulations to control insect pests but, as the scale of agriculture expanded to meet the needs of the global population, concerns about the negative impacts of agricultural practices on biodiversity have grown. While biological solutions, such as biological control agents and pheromones, have previously had relatively minor roles in pest management, biotechnology has opened the door to numerous new approaches for controlling insect pests. In this review, we look at how advances in synthetic biology and biotechnology are providing new options for pest control. We discuss emerging technologies for engineering resistant crops and insect populations and examine advances in biomanufacturing that are enabling the production of new products for pest control.     

A novel in vitro propagation system for West Indian elm [Guazuma ulmifolia Lam. (Malvaceae)]: a valuable medicinal woody species

In Vitro Cellular & Developmental Biology - Plant - The aim of this study was to establish a system of in vitro germination and propagation of Guazuma ulmifolia Lam. microcuttings (Malvaceae)....