Capture efficiency of magnetic nanoparticles through the compaction effect of a microparticles column.

When a magnetic nanoparticle solution flows through a porous medium formed by iron microparticles packed in a microfluidic channel, the nanoparticles get trapped within the column in the presence of a magnet. A complex interplay between magnetic and fluid forces within the magnetized porous medium governs the trapping of nanoparticles. However, how does the packing state of the microparticles affect the trapping of nanoparticles? Will more nanoparticles be trapped on a loose or a tight packing? In this work, we present experiments that show that the capture of nanoparticles is determined by the total volume occupied by the column, independent of its packing density. We present a simple analytical model based on the competition of drag and magnetic forces that shows that our system can be useful to develop and test more complete and accurate models. We also developed a technique to measure the columns' minute mass and its packing density, which consists of injecting polydimethylsiloxane into the acrylic microfluidic device. Our work can help with the optimization of environmental and biomedical applications based on high-gradient magnetic nanoparticle separation.

Lucilia bufonivora, Not Lucilia silvarum (Diptera: Calliphoridae), Causes Myiasis in Anurans in North America With Notes About Lucilia elongata and Lucilia thatuna.

In North America, until recently, all cases of anuran myiasis were attributed to Lucilia silvarum (Meigen) or Lucilia elongata Shannon. The latter species is exceedingly rare and its life history is unknown, but L. silvarum is common and was thought to be capable of being either parasitic or saprophytic in North America. Until recently, the anuran parasite Lucilia bufonivora Moniez was thought to be strictly Palearctic, but a study in 2014 has determined this species is established throughout southern Canada. In 2019, a study demonstrated, with molecular and morphological evidence, that two adult flies formerly identified as L. silvarum and reared from amphibian myiasis cases from Canada, are actually L. bufonivora. Although the mentioned study detected relatively high genetic distances with European L. bufonivora, the lack of evident morphological differentiation suggest that they are the same species. The current study examined 12 adult males and eleven adult females morphologically from three additional North American studies. Specimens were examined which had been identified as L. silvarum or L. elongata, and they all proved to be L. bufonivora. We now suspect L. silvarum is strictly saprophagous in North America like they are in the Palearctic Region. We also provide evidence that the pattern of myiasis differs between European and North American specimens.

Ecological and geographical speciation in Lucilia bufonivora: The evolution of amphibian obligate parasitism.

Lucilia (Diptera: Calliphoridae) is a genus of blowflies comprised largely of saprophagous and facultative parasites of livestock. Lucilia bufonivora, however, exhibits a unique form of obligate parasitism of amphibians, typically affecting wild hosts. The evolutionary route by which amphibian myiasis arose, however, is not well understood due to the low phylogenetic resolution in existing nuclear DNA phylogenies. Furthermore, the timing of when specificity for amphibian hosts arose in L. bufonivora is also unknown. In addition, this species was recently reported for the first time in North America (Canada) and, to date, no molecular studies have analysed the evolutionary relationships between individuals from Eastern and Western hemispheres. To provide broader insights into the evolution of the amphibian parasitic life history trait and to estimate when the trait first arose, a time-scaled phylogeny was inferred from a concatenated data set comprising mtDNA, nDNA and non-coding rDNA (COX1, per and ITS2 respectively). Specimens from Canada, the UK, Poland, Switzerland, the Netherlands and Germany were analysed, as well as individuals from its sister taxa, the saprophage Lucilia silvarum and a Nearctic species also implicated in amphibian myiasis, Lucilia elongata. Obligate amphibian parasitism appears to have arisen ~4 mya, likely as a result of niche displacement of a saprophagous/facultative parasite ancestor. Consistent paraphyly of L. bufonivora with respect to L. elongata across single-gene phylogenies and high mtDNA genetic distances between Nearctic and Palearctic individuals suggest on-going cryptic speciation facilitated by geographical isolation. These findings suggest that recent reports of L. bufonivora in the Nearctic do not constitute a recent introduction, but instead suggest that it remained unrecorded due to taxonomic confusion and low abundance. This is the first study to confirm the involvement of L. bufonivora in amphibian myiasis in Canada using DNA-based identification methods.

The toad fly Lucilia bufonivora: its evolutionary status and molecular identification.

The blow fly genus Lucilia is composed largely of saprophages and facultative myasis agents, including the economically important species Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) and Lucilia sericata (Meigen). Only one species is generally recognized as an obligate agent of myiasis, Lucilia bufonivora Moniez, and this is an obligate parasite of toads. Lucilia silvarum (Meigen), a sister species, behaves mainly as a carrion breeder; however, it has also been reported as a facultative parasite of amphibians. Morphologically, these species are almost identical, and historically this has led to misidentification, taxonomic ambiguity and a paucity of studies of L. bufonivora. In this study, dipterous larvae were analysed from toad myiasis cases from the U.K., The Netherlands and Switzerland, together with adult specimens of fly species implicated in amphibian parasitism: L. bufonivora, L. silvarum and Lucilia elongata Shannon (from North America). Partial sequences of two genes, cox1 and ef1α, were amplified. Seven additional blow fly species were analysed as outgroups. Bayesian inference trees of cox1, ef1α and a combined-gene dataset were constructed. All larvae isolated from toads were identified as L. bufonivora and no specimens of L. silvarum were implicated in amphibian myiasis. This study confirms L. silvarum and L. bufonivora as distinct sister species and provides unambiguous molecular identification of L. bufonivora.

Spatial and temporal habitat partitioning by calliphorid blowflies.

Calliphorid blowflies perform an essential ecosystem service in the consumption, recycling and dispersion of carrion nutrients and are considered amongst the most important functional groups in an ecosystem. Some species are of economic importance as facultative agents of livestock myiasis. The interspecific ecological differences that facilitate coexistence within the blowfly community are not fully understood. The aim of this work was to quantify differences in habitat use by calliphorid species. Thirty traps were distributed among three habitats at two sites in southwest England for collections made during March-August 2016. A total of 17 246 specimens were caught, of which 2427 were Lucilia sericata, 51 Lucilia richardsi, 6580 Lucilia caesar, 307 Lucilia ampullacea, 4881 Calliphora vicina and 2959 Calliphora vomitoria (all: Diptera: Calliphoridae). Lucilia sericata was the dominant species in open habitats, whereas L. caesar was the most abundant species in shaded habitats. Calliphora specimens were more abundant in the cooler months. These findings suggest that Calliphora and Lucilia species show strong temporal segregation mediated by temperature, and that species of the genus Lucilia show differences in the use of habitats that are likely to be driven by differences in humidity tolerance and light intensity. These factors in combination result in effective niche partitioning.

Morphological reassessment and molecular phylogenetic analyses of Amauroderma s.lat. raised new perspectives in the generic classification of the Ganodermataceae family.

Ganodermataceae is a remarkable group of polypore fungi, mainly characterized by particular double-walled basidiospores with a coloured endosporium ornamented with columns or crests, and a hyaline smooth exosporium. In order to establish an integrative morphological and molecular phylogenetic approach to clarify relationship of Neotropical Amauroderma s.lat. within the Ganodermataceae family, morphological analyses, including scanning electron microscopy, as well as a molecular phylogenetic approach based on one (ITS) and four loci (ITS-5.8S, LSU, TEF-1α and RPB1), were carried out. Ultrastructural analyses raised up a new character for Ganodermataceae systematics, i.e., the presence of perforation in the exosporium with holes that are connected with hollow columns of the endosporium. This character is considered as a synapomorphy in Foraminispora, a new genus proposed here to accommodate Porothelium rugosum (≡ Amauroderma sprucei). Furtadoa is proposed to accommodate species with monomitic context: F. biseptata, F. brasiliensis and F. corneri. Molecular phylogenetic analyses confirm that both genera grouped as strongly supported distinct lineages out of the Amauroderma s.str. clade.

Flow-mediated coupling on projectiles falling within a superlight granular medium.

Interesting collective motion emerges when several heavy intruder disks fall in a loose packed, quasi-two-dimensional granular bed of extremely light grains [F. Pacheco-Vázquez and J. C. Ruiz-Suárez, Nat. Commun. 1, 123 (2010)]. In particular, when two disks impact side by side, they initially repel and then they attract each other until they finally stop. Here we perform experiments and discrete-element soft-particle simulations to determine the range of action and the origin of these attractive and repulsive flow-mediated forces. We find that (1) the drag force on the disks fluctuate with a characteristic length linked to force chains that build up and break; (2) the repulsive force is present when the separation of the intruder disks is less than 6 times the size of the grains of the granular bed, which is the size of an aperture that allows a continuous discharge flow from a container; (3) the attractive force has a range of action between 5 and 6 times the size of the intruder disks; and (4) attraction exists only when intruders move faster than 1 m/s. These results suggest that repulsion originates from jamming of grains between intruders, and it supports the idea that attraction could be due to a "granular pressure" drop in the region between intruders caused by a high flow velocity of grains: a Bernoulli-like effect. However, our results do not rule out other mechanisms of interaction, like fluctuation-induced forces.

Infinite penetration of a projectile into a granular medium.

An object falling in a fluid reaches a terminal velocity when the drag force and its weight are balanced. Contrastingly, an object impacting into a granular medium rapidly dissipates all its energy and comes to rest always at a shallow depth. Here we study, experimentally and theoretically, the penetration dynamics of a projectile in a very long silo filled with expanded polystyrene particles. We discovered that, above a critical mass, the projectile reaches a terminal velocity and, therefore, an endless penetration.

Association study of ghrelin receptor gene polymorphisms in rheumatoid arthritis.

OBJECTIVES: Ghrelin is a newly characterised growth hormone (GH) releasing peptide widely distributed that may play an important role in the regulation of metabolic balance in inflammatory diseases such as rheumatoid arthritis (RA) by decreasing the pro-inflammatory Th1 responses. In this study we investigated the possible contribution of several polymorphisms in the functional Ghrelin receptor to RA susceptibility. METHODS: A screening of 3 single nucleotide polymorphisms (SNPs) was performed in a total of 950 RA patients and 990 healthy controls of Spanish Caucasian origin. Genotyping of all 3 SNPs was performed by real-time polymerase chain reaction technology, using the TaqMan 5'-allele discrimination assay. RESULTS: We observed no statistically significant deviation between RA patients and controls for the GHSR SNPs analysed. In addition, we performed a haplotype analysis that did not reveal an association with RA susceptibility. The stratification analysis for the presence of shared epitope (SE), rheumatoid factor (RF) or antibodies anti cyclic citrullinated peptide (anti-CCP) did not detect significant association of the GHSR polymorphisms with RA. CONCLUSIONS: These findings suggest that the GHSR gene polymorphisms do not appear to play a major role in RA genetic predisposition in our population.

Rheology of a sonofluidized granular packing.

We report experimental measurements on the rheology of a dry granular material under a weak level of vibration generated by sound injection. First, we measure the drag force exerted on a wire moving in the bulk. We show that when the driving vibration energy is increased, the effective rheology changes drastically: going from a non-linear dynamical friction behavior --weakly increasing with the velocity-- up to a linear force-velocity regime. We present a simple heuristic model to account for the vanishing of the stress dynamical threshold at a finite vibration intensity and the onset of a linear force-velocity behavior. Second, we measure the drag force on spherical intruders when the dragging velocity, the vibration energy, and the diameters are varied. We evidence a so-called "geometrical hardening" effect for smaller-size intruders and a logarithmic hardening effect for the velocity dependence. We show that this last effect is only weakly dependent on the vibration intensity.

Species relations among wild Arachis species with the A genome as revealed by FISH mapping of rDNA loci and heterochromatin detection.

Section Arachis of the homonymous genus includes 29 wild diploid species and two allotetraploids (A. monticola and the domesticated peanut, A. hypogaea L.). Although, three different genomes (A, B and D) have been proposed for diploid species with x = 10, they are still not well characterized. Moreover, neither the relationships among species within each genome group nor between diploids and tetraploids (AABB) are completely resolved. To tackle these issues, particularly within the A genome, in this study the rRNA genes (5S and 18S-26S) and heterochromatic bands were physically mapped using fluorescent in situ hybridization (FISH) in 13 species of Arachis. These molecular cytogenetic landmarks have allowed individual identification of a set of chromosomes and were used to construct detailed FISH-based karyotypes for each species. The bulk of the chromosome markers mapped revealed that, although the A genome species have a common karyotype structure, the species can be arranged in three groups (La Plata River Basin, Chiquitano, and Pantanal) on the basis of the variability observed in the heterochromatin and 18S-26S rRNA loci. Notably, these groups are consistent with the geographical co-distribution of the species. This coincidence is discussed on the basis of the particular reproductive traits of the species such as autogamy and geocarpy. Combined with geographic distribution of the taxa, the cytogenetic data provide evidence that A. duranensis is the most probable A genome ancestor of tetraploid species. It is expected that the groups of diploid species established, and their relation with the cultigen, may aid to rationally select wild species with agronomic traits desirable for peanut breeding programs.

Effect of zinc upon human and murine cell viability and differentiation.

Most zinc studies show its benefits or changes that coincide with its deficiency, but some have reported damages by supplements. In this work, the effects of zinc in different cell lines (U-937, human monocytes, and murine bone marrow cells) were analyzed. The cells were put in their specific culture medium either alone or with a stimulant [1-phorbol 12-myristate 13-acetate (PMA) for U-937 and monocytes, granulocyte macrophage colony stimulating factor (GM-CSF) for bone marrow cells]. These preparations, with or without zinc (0.05 to 1.0 mM), were incubated and microscopically analyzed on days 3, 9, and 11. The viability of all cells cultivated with 0.05 and 0.1 mM of zinc was similar to that of the controls without zinc (90%). With 1.0 mM of zinc, the viability diminished (p < 0.005) to 80% in U-937 and to 50% in monocytes and bone marrow cells; the number of cells increased in the three lines, but there was no differentiation. We conclude that the effects observed with different doses of zinc vary not only among the different species but also according to the time the cells were exposed to the metal. The same doses of zinc can have either a stimulatory or an inhibitory effect.

Association study of PTPN22 C1858T polymorphism in Trypanosoma cruzi infection.

In this study we investigated a possible role for the single nucleotide polymorphism C1858T of the PTPN22 (protein tyrosine phosphatase nonreceptor 22) gene in determining the susceptibility to Trypanosoma cruzi infection, as well as in development of chagasic heart disease. This study included 316 patients with Chagas' disease and 520 healthy individuals from Colombia and Peru. Genotyping of PTPN22 was performed by the real-time polymerase chain reaction technology, using the TaqMan 5' allelic discrimination assay. No statistically significant differences in the frequency of PTPN22 C1858T gene polymorphism between chagasic patients and controls or between asymptomatic and cardiomyopathic individuals were observed. Our findings suggest that the PTPN22 polymorphism analyzed does not play a major role in the development of Chagas' disease in the Colombian and Peruvian populations.

Contribution of MHC class I region to genetic susceptibility for giant cell arteritis.

OBJECTIVE: The aim of this study was to assess the potential contribution of HLA-class I MICA and HLA-B gene polymorphisms towards the pathogenesis of giant cell arteritis (GCA). METHODS: Ninety-eight biopsy-proven GCA patients and 225 ethnically matched controls from Lugo, Northwest Spain, were genotyped for the MICA-TM microsatellite polymorphism using a polymerase chain reaction (PCR)-based method. Genotyping of HLA-B was performed using PCR and detection with a reverse sequence-specific oligonucleotide (SSO) probes system. RESULTS: A significant difference in the distribution of the alleles of MICA between patient and control groups (P = 0.005) was found. This was due to an increased frequency of the MICA A5 allele in GCA patients compared with controls (26 vs 13.6%; P = 0.0001; P(C) = 0.0005; OR 2.2, 95% CI 1.4-3.4). In addition, the HLA-B*15 allele showed a higher frequency in GCA patients compared with controls (P = 0.004; P(C) = 0.04; OR 2.7, 95% CI 1.3-5.7). Interestingly, the association observed with the MICA A5 allele seems to be independent of linkage disequilibrium with HLA-B, as well as independent of that previously described with HLA-DRB1*04. Remarkably, simultaneous presence of MICA A5 and HLA-B*15 or HLA-DRB1*04 genetic markers leads to an increase in the OR obtained for each individual genetic marker (MICA A5 + B*15 OR 3.2; MICA A5 + DRB1*04 OR 5.8). CONCLUSIONS: Our results provide the first evidence that the MICA and HLA-B genes are independently associated with the genetic susceptibility to GCA, and suggest that several genes within the MHC might have independent effects in the susceptibility to this systemic vasculitis.

Novel method for aroma recovery from the bioconversion of lutein to beta-ionone by Trichosporon asahii using a mesoporous silicate material.

In this work, we report on the synthesis and ability of the mesoporous material MCM-41 to adsorb the norisoprenoid beta-ionone. This compound, with a violet aroma note, can be produced from lutein by the yeast Trichosporon asahii through a bioconversion process. We found that beta-ionone inhibited the yeast growth and constrained aroma formation. Growth inhibition was overcome using silicate MCM-41 as sorbent device in a fermentation system that allowed product removal from the culture medium by headspace manipulation. Compared to a commercial silica gel, the mesoporous material exhibited a 4.5-fold higher beta-ionone adsorption. Contrasting to cultures without the sorbent device, the presence of MCM-41 allowed a marked increase (14-fold) in beta-ionone production. Our results suggested that confinement of the norisoprenoid into the sorbent material bypassed its toxicity which allowed a better beta-ionone production. This study represents the first report on the use of MCM-41 to recover an aroma produced by fermentation and therefore, a novel application for a mesoporous material.

The mitogen-activated protein kinase pathway can inhibit TRAIL-induced apoptosis by prohibiting association of truncated Bid with mitochondria.

Breast cancer cells often show increased activity of the mitogen-activated protein kinase (MAPK) pathway. We report here that this pathway reduces their sensitivity to death ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and present the underlying mechanism. Activation of protein kinase C (PKC) inhibited TRAIL-induced apoptosis in a protein synthesis-independent manner. Deliberate activation of MAPK was also inhibitory. In digitonin-permeabilized cells, PKC activation interfered with the capacity of recombinant truncated (t)Bid to release cytochrome c from mitochondria. MAPK activation did not affect TRAIL or tumor necrosis factor (TNF)alpha-induced Bid cleavage. However, it did inhibit translocation of (t)Bid to mitochondria as determined both by subcellular fractionation analysis and confocal microscopy. Steady state tBid mitochondrial localization was prohibited by activation of the MAPK pathway, also when the Bcl-2 homology domain 3 (BH3) domain of tBid was disrupted. We conclude that the MAPK pathway inhibits TRAIL-induced apoptosis in MCF-7 cells by prohibiting anchoring of tBid to the mitochondrial membrane. This anchoring is independent of its interaction with resident Bcl-2 family members.

Production of tobacco aroma from lutein. Specific role of the microorganisms involved in the process.

A mixed culture formed by Bacillus sp. and Geotrichum sp. produced tobacco aroma compounds from the carotenoid lutein through the formation of the intermediate beta-ionone. Both microorganisms can grow independently in a medium supplemented with lutein, but only Geotrichum produces beta-ionone. This intermediate was incorporated by the bacilli, converted to aroma and this product excreted to the culture medium. Bacillus sp. did not utilize beta-ionone for growth but modified it. We conclude that, in the bioconversion of lutein to products with tobacco aroma, Geotrichum sp. is involved in carotenoid oxidation to produce beta-ionone and Bacillus sp. is responsible for the norisoprenoid reduction to produce 7,8-dihydro-beta-ionone and 7,8-dihydro-beta-ionol.