Biomimetic hydroxyapatite nanocrystals are an active carrier for Salmonella bacteriophages

open access articlePurpose: The use of bacteriophages represents a valid alternative to conventional antimicrobial treatments, overcoming the widespread bacterial antibiotic resistance phenomenon. In this work, we evaluated whether biomimetic hydroxyapatite (HA) nanocrystals are able to enhance some properties of bacteriophages. The final goal of this study was to demonstrate that biomimetic HA nanocrystals can be used for bacteriophage delivery in the context of bacterial infections, and contribute – at the same time – to enhance some of the biological properties of the same bacteriophages such as stability, preservation, antimicrobial activity, and so on. Materials and methods: Phage isolation and characterization were carried out by using Mitomycin C and following double-layer agar technique. The biomimetic HA water suspension was synthesized in order to obtain nanocrystals with plate-like morphology and nanometric dimensions. The interaction of phages with the HA was investigated by dynamic light scattering and Zeta potential analyses. The cytotoxicity and intracellular killing activities of the phage–HA complex were evaluated in human hepatocellular carcinoma HepG2 cells. The bacterial inhibition capacity of the complex was assessed on chicken minced meat samples infected with Salmonella Rissen. Results: Our data highlighted that the biomimetic HA nanocrystal–bacteriophage complex was more stable and more effective than phages alone in all tested experimental conditions. Conclusion: Our results evidenced the important contribution of biomimetic HA nanocrystals: they act as an excellent carrier for bacteriophage delivery and enhance its biological characteristics. This study confirmed the significant role of the mineral HA when it is complexed with biological entities like bacteriophages, as it has been shown for molecules such as lactoferrin

African genomes illuminate the early history and transition to selfing in Arabidopsis thaliana

Over the past 20 y, many studies have examined the history of the plant ecological and molecular model, Arabidopsis thaliana, in Europe and North America. Although these studies informed us about the recent history of the species, the early history has remained elusive. In a large-scale genomic analysis of African A. thaliana, we sequenced the genomes of 78 modern and herbarium samples from Africa and analyzed these together with over 1,000 previously sequenced Eurasian samples. In striking contrast to expectations, we find that all African individuals sampled are native to this continent, including those from sub-Saharan Africa. Moreover, we show that Africa harbors the greatest variation and represents the deepest history in the A. thaliana lineage. Our results also reveal evidence that selfing, a major defining characteristic of the species, evolved in a single geographic region, best represented today within Africa. Demographic inference supports a model in which the ancestral A. thaliana population began to split by 120-90 kya, during the last interglacial and Abbassia pluvial, and Eurasian populations subsequently separated from one another at around 40 kya. This bears striking similarities to the patterns observed for diverse species, including humans, implying a key role for climatic events during interglacial and pluvial periods in shaping the histories and current distributions of a wide range of species.Peer Reviewe

The Union is Strength: The Synergic Action of Long Fatty Acids and a Bacteriophage against Xanthomonas campestris Biofilm

Xanthomonas campestris pv. campestris is known as the causative agent of black rot disease, which attacks mainly crucifers, severely lowering their global productivity. One of the main virulence factors of this pathogen is its capability to penetrate and form biofilm structures in the xylem vessels. The discovery of novel approaches to crop disease management is urgent and a possible treatment could be aimed at the eradication of biofilm, although anti-biofilm approaches in agricultural microbiology are still rare. Considering the multifactorial nature of biofilm, an effective approach against Xanthomonas campestris implies the use of a multi-targeted or combinatorial strategy. In this paper, an anti-biofilm strategy based on the use of fatty acids and the bacteriophage (Xccφ1)-hydroxyapatite complex was optimized against Xanthomonas campestris mature biofilm. The synergic action of these elements was demonstrated and the efficient removal of Xanthomonas campestris mature biofilm was also proven in a flow cell system, making the proposed approach an effective solution to enhance plant survival in Xanthomonas campestris infections. Moreover, the molecular mechanisms responsible for the efficacy of the proposed treatment were explored

A two-step adaptive walk rewires nutrient transport in a challenging edaphic environment

Most well-characterized cases of adaptation involve single genetic loci. Theory suggests that multilocus adaptive walks should be common, but these are challenging to identify in natural populations. Here, we combine trait mapping with population genetic modeling to show that a two-step process rewired nutrient homeostasis in a population of Arabidopsis as it colonized the base of an active stratovolcano characterized by extremely low soil manganese (Mn). First, a variant that disrupted the primary iron (Fe) uptake transporter gene (IRT1) swept quickly to fixation in a hard selective sweep, increasing Mn but limiting Fe in the leaves. Second, multiple independent tandem duplications occurred at NRAMP1 and together rose to near fixation in the island population, compensating the loss of IRT1 by improving Fe homeostasis. This study provides a clear case of a multilocus adaptive walk and reveals how genetic variants reshaped a phenotype and spread over space and time

Italian Guidelines in diagnosis and treatment of alopecia areata

Alopecia areata (AA) is an organ-specific autoimmune disorder that targets anagen phase hair follicles. The course is unpredictable and current available treatments have variable efficacy. Nowadays, there is relatively little evidence on treatment of AA from well-designed clinical trials. Moreover, none of the treatments or devices commonly used to treat AA are specifically approved by the Food and Drug Administration. The Italian Study Group for Cutaneous Annexial Disease of the Italian Society of dermatology proposes these Italian guidelines for diagnosis and treatment of Alopecia Areata deeming useful for the daily management of the disease. This article summarizes evidence-based treatment associated with expert-based recommendations

Ancient pigs reveal a near-complete genomic turnover following their introduction to Europe

Archaeological evidence indicates that pig domestication had begun by ~10,500 y before the present (BP) in the Near East, and mitochondrial DNA (mtDNA) suggests that pigs arrived in Europe alongside farmers ~8,500 y BP. A few thousand years after the introduction of Near Eastern pigs into Europe, however, their characteristic mtDNA signature disappeared and was replaced by haplotypes associated with European wild boars. This turnover could be accounted for by substantial gene flow from local Euro-pean wild boars, although it is also possible that European wild boars were domesticated independently without any genetic con-tribution from the Near East. To test these hypotheses, we obtained mtDNA sequences from 2,099 modern and ancient pig samples and 63 nuclear ancient genomes from Near Eastern and European pigs. Our analyses revealed that European domestic pigs dating from 7,100 to 6,000 y BP possessed both Near Eastern and European nuclear ancestry, while later pigs possessed no more than 4% Near Eastern ancestry, indicating that gene flow from European wild boars resulted in a near-complete disappearance of Near East ancestry. In addition, we demonstrate that a variant at a locus encoding black coat color likely originated in the Near East and persisted in European pigs. Altogether, our results indicate that while pigs were not independently domesticated in Europe, the vast majority of human-mediated selection over the past 5,000 y focused on the genomic fraction derived from the European wild boars, and not on the fraction that was selected by early Neolithic farmers over the first 2,500 y of the domestication process

LACTOFERRIN ADSORBED ONTO BIOMIMETIC HYDROXYAPATITE: A MULTIFUNCTIONAL ANTIMICROBIAL MOLECULE

Lactoferrin (LF), is an iron-binding protein, belonging to transferrin family. It is found in the mucosal secretions (tears, saliva, milk, and colostrums) of the majority of mammalian species, including humans. LF is a multitask molecule: it partecipates to iron absorption and distribution, but also displays anti-inflammatory, antioxidant, anticarcinogenic, and antimicrobial properties. Hydroxyapatite (HA) plays an important role in the formation of the bony skeleton and bone remodeling. Alteration of HA metabolism can cause serious clinical consequences, such as arterial calcification, chronic kidney disease or osteoporosis. HA is also used in numerous bioengineering and biomedical applications - due to its bioactivity and osteoconductivity – and also as vehicle for drug targeting, bone scaffolds and implant coating materials, filler in polymeric matrices. In this project, the biological properties (such as antimicrobial, immunomodulatory and antioxidant activities) of lactoferrin adsorbed onto biomimetic hydroxyapatatite nanocrystals (LF-HA) were evaluated. After the biological characterization, the complex was embedded in an active packaging system (on a cling film) - by electrodeposition - to estimate the antioxidant property of this active packaging system. Packaging protects food from external pathogen contamination and environmental factors (oxygen, moisture and heat), providing longer product shelf life and avoiding the quality decay. Shelf life prolongation is possible by controlling enzymatic and microbial activities through the control of temperature, addition of salt, or by removing oxygen. In recent years, foods preserved with natural additives have become very popular due to the great consumer awareness and concern regarding synthetic chemical additives. The tests carried out showed the antimicrobial and antioxidant efficacy of LF-HA versus the lactoferrin alone, when tested at the same concentrations, and the effectiveness of this molecule embedded in a food packaging system. The results obtained permit to conclude that the chemical manipulation of the lactoferrin significantly improved the antimicrobial and antioxidant activities of the native molecule. The main characteristics of the food packaging system obtained by electrodeposition of LF-HA on cling film are: uniform coating with LF-HA obtained throughout a new method of electrodeposition; long lasting stability, when stored for six months or longer at room temperature before being used to protect the food; stable to deep freezing, for six months or more

Phage therapy: a crosslink between human and plants bacterial infection.

Bacteria are under constant attack by bacteriophages (phages), the most abundant life forms in the biosphere. This work describes how the phage therapy is an efficient way to contrast the bacterial infection regardless the host. Here we describe the activity of phage in both plant and chicken meat. All the experiment carried out are with phage complex whit the hydroxyapatite, since many years, hydroxyapatite is being explored as vehicle for drug targeting, transfection, bone scaffolds and implant coating materials and, for these reasons we evaluated the effect of this mineral for the bacteriophage therapy. At first, we validated the antimicrobial activity of the phage and its possible direct administration into the plant xylem. We next performed both in vivo and in vitro experiments to assess the activity of the bacteriophage in association whit hydroxyapatite; seconds, we demonstrate that the hydroxyapatite/bacteriophage complex was able to reduce the bacterial load of Salmonella Rissen in previously infected minced meat, respect to bacteriophage or hydroxyapatite alone

Salmonella Rissen Φ1: a molecular switch

Introduction: Bacteria develop resistance against phages by losing the phage receptor or reducing its binding specificity or by a temporary change of phage receptor specificity. Here we describe the phage resistance mechanism adopted by S. Rissen which acts through a molecular switch. Material & Methods: Phage was isolated from the S. Rissen strain (RW) and used to select the phage resistant strain RRϕ1+. We evaluate both the differences in bacterial morphology and the genetic variations between the two strains by biochemical and comparative genomic analyses. Results: Biochemical analyses showed that the presence of the phage influences biofilm production, phage resistance and the switch of the O-antigen from smooth to rough, Genomic analysis showed that the sensitive and resistant strains differ by 10 genes. Only the phosphomannomutase_1 and 2 genes, involved in mannose synthesis pathway, showed different expression levels. The SNP of the two genes are located near HTs known to regulate phase variation. We used S rissen to see whether a character under strong selection pressure- such as phage resistance is repeatable. In four independent experiment phage resistance was acquired by the same molecular mechanism. Conclusion: S. rissen uses the same and evolutionary flexible tool (phase variation) to control several characters: biofilm production, phage resistance, and O-antigen structure