Origin of the invasive Arundo donax (Poaceae): a trans-Asian expedition in herbaria

Background and Aims

The hypothesis of an ancient introduction, i.e. archaeophyte origin, is one of the most challenging questions in phylogeography. Arundo donax (Poaceae) is currently considered to be one of the worst invasive species globally, but it has also been widely utilzed by man across Eurasia for millennia. Despite a lack of phylogenetic data, recent literature has often speculated on its introduction to the Mediterranean region.

Methods

This study tests the hypothesis of its ancient introduction from Asia to the Mediterranean by using plastid DNA sequencing and morphometric analysis on 127 herbarium specimens collected across sub-tropical Eurasia. In addition, a bioclimatic species distribution model calibrated on 1221 Mediterranean localities was used to identify similar ecological niches in Asia.

Key Results

Despite analysis of several plastid DNA hypervariable sites and the identification of 13 haplotypes, A. donax was represented by a single haplotype from the Mediterranean to the Middle East. This haplotype is shared with invasive samples worldwide, and its nearest phylogenetic relatives are located in the Middle East. Morphometric data characterized this invasive clone by a robust morphotype distinguishable from all other Asian samples. The ecological niche modelling designated the southern Caspian Sea, southern Iran and the Indus Valley as the most suitable regions of origin in Asia for the invasive clone of A. donax.

Conclusions

Using an integrative approach, an ancient dispersion of this robust, polyploid and non-fruiting clone is hypothesized from the Middle East to the west, leading to its invasion throughout the Mediterranean Basin.     

Trends in Condom Use and Risk Behaviours after Sexual Exposure to HIV: A Seven-Year Observational Study

Objective

We aimed to determine the trends in numbers and percentages of sexually exposed persons to HIV (SE) consulting an ED for post-exposure prophylaxis (PEP), as well as predictors of condom use.

Study Design

We conducted a prospective-observational study.

Methods

We included all SE attendances in our Emergency Department (ED) during a seven-year study-period (2006–2012). Trends were analyzed using time-series analysis. Logistic Regression was used to define indicators of condom use.

Results

We enrolled 1851 SE: 45.7% reported intercourse without condom-use and 12.2% with an HIV-infected partner. Significant (p<0.01) rising trends were observed in the overall number of SE visits (+75%), notably among men having sex with men (MSM) (+126%). There were rising trends in the number and percentage of those reporting intercourse without condom-use in the entire population +91% (p<0.001) and +1% (p>0.05), in MSM +228% (p<0.001) and +49% (p<0.001), in Heterosexuals +68% (p<0.001) and +10% (p = 0.08). Among MSM, significant rising trends were found in those reporting high-risk behaviours: anal receptive (+450% and +76%) and anal insertive (+l33% and +70%) intercourses. In a multivariate logistic regression analysis, heterosexuals, vaginal intercourse, visit during the night-shift and short time delay between SE and ED visit, were significantly associated with condom-use.

Conclusion

We report an increasing trend in the number of SE, mainly among MSM, and rising trends in high-risk behaviours and unprotected sexual intercourses among MSM. Our results indicate that SE should be considered as a high-risk population for HIV and sexually transmitted diseases.     

Draft genome sequence of marine alphaproteobacterial strain HIMB11, the first cultivated representative of a unique lineage within the Roseobacter clade possessing an unusually small genome

Strain HIMB11 is a planktonic marine bacterium isolated from coastal seawater in Kaneohe Bay, Oahu, Hawaii belonging to the ubiquitous and versatile Roseobacter clade of the alphaproteobacterial family Rhodobacteraceae. Here we describe the preliminary characteristics of strain HIMB11, including annotation of the draft genome sequence and comparative genomic analysis with other members of the Roseobacter lineage. The 3,098,747 bp draft genome is arranged in 34 contigs and contains 3,183 protein-coding genes and 54 RNA genes. Phylogenomic and 16S rRNA gene analyses indicate that HIMB11 represents a unique sublineage within the Roseobacter clade. Comparison with other publicly available genome sequences from members of the Roseobacter lineage reveals that strain HIMB11 has the genomic potential to utilize a wide variety of energy sources (e.g. organic matter, reduced inorganic sulfur, light, carbon monoxide), while possessing a reduced number of substrate transporters.     

Antiviral activity of recombinant ankyrin targeted to the capsid domain of HIV-1 Gag polyprotein

Background

Ankyrins are cellular mediators of a number of essential protein-protein interactions. Unlike intrabodies, ankyrins are composed of highly structured repeat modules characterized by disulfide bridge-independent folding. Artificial ankyrin molecules, designed to target viral components, might act as intracellular antiviral agents and contribute to the cellular immunity against viral pathogens such as HIV-1.

Results

A phage-displayed library of artificial ankyrins was constructed, and screened on a polyprotein made of the fused matrix and capsid domains (MA-CA) of the HIV-1 Gag precursor. An ankyrin with three modules named Ank^GAG1D4 (16.5 kDa) was isolated. Ank^GAG1D4 and MA-CA formed a protein complex with a stoichiometry of 1:1 and a dissociation constant of K _d ~ 1 ??M, and the Ank^GAG1D4 binding site was mapped to the N-terminal domain of the CA, within residues 1-110. HIV-1 production in SupT1 cells stably expressing Ank^GAG1D4 in both N-myristoylated and non-N-myristoylated versions was significantly reduced compared to control cells. Ank^GAG1D4 expression also reduced the production of MLV, a phylogenetically distant retrovirus. The Ank^GAG1D4-mediated antiviral effect on HIV-1 was found to occur at post-integration steps, but did not involve the Gag precursor processing or cellular trafficking. Our data suggested that the lower HIV-1 progeny yields resulted from the negative interference of Ank^GAG1D4-CA with the Gag assembly and budding pathway.

Conclusions

The resistance of Ank^GAG1D4-expressing cells to HIV-1 suggested that the CA-targeted ankyrin Ank^GAG1D4 could serve as a protein platform for the design of a novel class of intracellular inhibitors of HIV-1 assembly based on ankyrin-repeat modules.     

Small molecule inhibitors of the Yersinia type III secretion system impair the development of Chlamydia after entry into host cells

Background  

Chlamydiae are obligate intracellular pathogens that possess a type III secretion system to deliver proteins into the host cell during infection. Small molecule inhibitors of type III secretion in Yersinia, termed INPs (Innate Pharmaceuticals AB) were reported to strongly inhibit Chlamydia growth in epithelial cells. In this study we have analyzed the effect of these drugs on bacterial invasiveness.     

Clonal structure through space and time: High stability in the holothurian Stichopus chloronotus (Echinodermata)

Sea cucumbers are increasingly exploited for human consumption and for their curative properties, and many wild populations are now depleted or in danger of extinction. While aquaculture is seen as an alternative to fisheries and as a mean to restore wild populations, more knowledge is needed on their reproductive strategies to render this practice efficient, notably for fissiparous holothurians, which are some of the mobile animals able of asexual reproduction by transverse fission. Little information is available on their population genetic diversity and structure. Here, the clonal structure of populations of the fissiparous sea cucumber Stichopus chloronotus has been investigated using nine microsatellite loci and a random sampling, at different spatial (intra‐reef and inter‐reef) and temporal (inter‐season and inter‐year) scales. Our findings highlight the importance of asexual reproduction in maintaining these populations, and the prevalence of the “initial seedling recruitment” strategy (ISR), leading to a high stability of clonal composition over seasons and years. It also seemed that clonal propagation was limited to the reef scale (<10 km) while reefs were connected by sexual dispersal. This is the first time that clonal structure in sea cucumbers has been studied at such a fine scale, with a specific sampling strategy. It provides key findings on the genetic diversity and structure of fissiparous sea cucumbers, which will be useful for the management of wild populations and aquaculture.     

Reproductive biology,multiple paternity and polyandry of the bull shark Carcharhinus leucas

To improve understanding of bull shark Carcharhinus leucas reproductive biology, we analysed reproductive traits from 118 bull sharks caught along Reunion Island coasts (Western Indian Ocean), including 16 gravid females. Specific microsatellite loci were used to investigate the frequency of multiple paternity. Males and females reached maturity at c. 234 cm and 257 cm total length (L_T), respectively, and litter sizes ranged from 5 to 14 embryos. Analysis of the 16 litters collected in various months of the year indicated that parturition occurs between October and December, with a size at birth c. 60–80 cm L_T and that the gestation period is probably c. 12 months. Assuming a 1 year resting period and a period of sperm storage (4–5 months) between mating (in June–September) and fertilisation, the reproductive cycle of bull sharks at Reunion Island would be biennial. At least 56.25% of the litters investigated were polyandrous, sired by 2–5 males. Several males that each sired several litters conceived during the same or distinct mating seasons were detected, suggesting both a seasonal aggregation of sharks to mate and some male fidelity to mating site. Altogether, these findings provide valuable information for both shark risk management and conservation of the species in the Western Indian Ocean.     

Genetic and pathogenic diversity of Ralstonia solanacearum species complex strains isolated in Burkina Faso

Bacterial wilt caused by the Ralstonia solanacearum species complex (RSSC) is a disease that negatively affects the cultivation of Solanaceae crops in Burkina Faso. Knowledge of the pathogen diversity is essential to deploy locally adapted control methods. In this study, diseased plants showing typical bacterial wilt symptoms were collected in the three main agroclimatic zones of Burkina Faso for the detection of RSSC isolates. Strain characterization was achieved through a phylogenetic and pathogenicity diversity assessment. A total of 102 isolates were sampled, and Phylotype I (Ralstonia pseudosolanacearum) was predominant (n = 101; sequevars 14, 31, 34, and 46). The remaining isolate was characterized as Phylotype IIA-35 (Ralstonia solanacearum). Phylotypes I-31 and I-46 were predominant and both characterized as the most the aggressive group of strains amongst a subset of 33 representative isolates. Our findings provide valuable information as regard RSSC diversity that breeders and resistance programme should target in order to fight this pathogen in Burkina Faso and around the world.     

Purification and Characterization of the NAD-Dependent Glutamate Dehydrogenase in the Ectomycorrhizal FungusLaccaria bicolor(Maire) Orton

The NAD-dependent glutamate dehydrogenase (GDH) (EC 1.4.1.2) fromLaccaria bicolorwas purified 410-fold to apparent electrophoretic homogeneity with a 40% recovery through a three-step procedure involving ammonium sulfate precipitation, anion-exchange chromatography on DEAE–Trisacryl, and gel filtration. The molecular weight of the native enzyme determined by gel filtration was 470 kDa, whereas sodium dodecyl sulfate–polyacrylamide gel electrophoresis gave rise to a single band of 116 kDa, suggesting that the enzyme is composed of four identical subunits. The enzyme was specific for NAD(H). The pH optima were 7.4 and 8.8 for the amination and deamination reactions, respectively. The enzyme was found to be highly unstable, with virtually no activity after 20 days at −75°C, 4 days at 4°C, and 1 h at 50°C. The addition of ammonium sulfate improved greatly the stability of the enzyme and full activity was still observed after several months at −75°C. NAD-GDH activity was stimulated by Ca²⁺and Mg²⁺but strongly inhibited by Cu²⁺and slightly by the nucleotides AMP, ADP, and ATP. The Michaelis constants for NAD, NADH, 2-oxoglutarate, and ammonium were 282 μM, 89 μM, 1.35 mM, and 37 mM, respectively. The enzyme had a negative cooperativity for glutamate (Hill number of 0.3), and itsK_mvalue increased from 0.24 to 3.6 mM when the glutamate concentration exceeded 1 mM. These affinity constants of the substrates, compared with those of the NADP-GDH of the fungus, suggest that the NAD-GDH is mainly involved in the catabolism of glutamate, while the NADP-GDH is involved in the catalysis of this amino acid.