Genotoxicity and Cytotoxicity Evaluation of the Neolignan Analogue 2-(4-Nitrophenoxy)-1Phenylethanone and its Protective Effect Against DNA Damage

Neolignans are secondary metabolites found in various groups of Angiosperms. They belong to a class of natural compounds with great diversity of chemical structures and pharmacological activities. These compounds are formed by linking two phenylpropanoid units. Several compounds that have ability to prevent genetic damage have been isolated from plants, and can be used to prevent or delay the development of tumor cells. Genetic toxicology evaluation is widely used in risk assessment of new drugs in preclinical screening tests. In this study, we evaluated the genotoxicity and cytotoxicity of the neolignan analogue 2-(4-nitrophenoxy)-1-phenylethanone (4NF) and its protective effect against DNA damage using the mouse bone marrow micronucleus test and the comet assay in mouse peripheral blood. Our results showed that this neolignan analogue had no genotoxic activity and was able to reduce induced damage both in mouse bone marrow and peripheral blood. Although the neolignan analogue 4NF was cytotoxic, it reduced cyclophosphamide-induced cytotoxicity. In conclusion, it showed no genotoxic action, but exhibited cytotoxic, antigenotoxic, and anticytotoxic activities.     

Within-host competition between Borrelia afzelii ospC strains in wild hosts as revealed by massively parallel amplicon sequencing

Infections frequently consist of more than one strain of a given pathogen. Experiments have shown that co-infecting strains often compete, so that the infection intensity of each strain in mixed infections is lower than in single strain infections. Such within-host competition can have important epidemiological and evolutionary consequences. However, the extent of competition has rarely been investigated in wild, naturally infected hosts, where there is noise in the form of varying inoculation doses, asynchronous infections and host heterogeneity, which can potentially alleviate or eliminate competition. Here, we investigated the extent of competition between Borrelia afzelii strains (as determined by ospC genotype) in three host species sampled in the wild. For this purpose, we developed a protocol for 454 amplicon sequencing of ospC, which allows both detection and quantification of each individual strain in an infection. Each host individual was infected with one to six ospC strains. The infection intensity of each strain was lower in mixed infections than in single ones, showing that there was competition. Rank-abundance plots revealed that there was typically one dominant strain, but that the evenness of the relative infection intensity of the different strains in an infection increased with the multiplicity of infection. We conclude that within-host competition can play an important role under natural conditions despite many potential sources of noise, and that quantification by next-generation amplicon sequencing offers new possibilities to dissect within-host interactions in naturally infected hosts.     

Frequency‐dependent fitness in gynodioecious Lobelia siphilitica

Selection is frequency dependent when an individual's fitness depends on the frequency of its phenotype. Frequency‐dependent selection should be common in gynodioecious plants, where individuals are female or hermaphroditic; if the fitness of females is limited by the availability of pollen to fertilize their ovules, then they should have higher fitness when rare than when common. To test whether the fitness of females is frequency dependent, we manipulated the sex ratio in arrays of gynodioecious Lobelia siphilitica. To test whether fitness was frequency dependent because of variation in pollen availability, we compared open‐pollinated and supplemental hand‐pollinated plants. Open‐pollinated females produced more seeds when they were rare than when they were common, as expected if fitness is negatively frequency dependent. However, hand‐pollinated females also produced more seeds when they were rare, indicating that variation in pollen availability was not the cause of frequency‐dependent fitness. Instead, fitness was frequency dependent because both hand‐ and open‐pollinated females opened more flowers when they were rare than when they were common. This plasticity in the rate of anthesis could cause fitness to be frequency dependent even when reproduction is not pollen limited, and thus expand the conditions under which frequency‐dependent selection operates in gynodioecious species.     

Escape of Sgs1 from Rad9 inhibition reduces the requirement for Sae2 and functional MRX in DNA end resection

Homologous recombination requires nucleolytic degradation (resection) of DNA double‐strand break (DSB) ends. In Saccharomyces cerevisiae, the MRX complex and Sae2 are involved in the onset of DSB resection, whereas extensive resection requires Exo1 and the concerted action of Dna2 and Sgs1. Here, we show that the checkpoint protein Rad9 limits the action of Sgs1/Dna2 in DSB resection by inhibiting Sgs1 binding/persistence at the DSB ends. When inhibition by Rad9 is abolished by the Sgs1‐ss mutant variant or by deletion of RAD9, the requirement for Sae2 and functional MRX in DSB resection is reduced. These results provide new insights into how early and long‐range resection is coordinated.     

H-Ferritin-Regulated MicroRNAs Modulate Gene Expression in K562 Cells

In a previous study, we showed that the silencing of the heavy subunit (FHC) offerritin, the central iron storage molecule in the cell, is accompanied by a modification in global gene expression. In this work, we explored whether different FHC amounts might modulate miRNA expression levels in K562 cells and studied the impact of miRNAs in gene expression profile modifications. To this aim, we performed a miRNA-mRNA integrative analysis in K562 silenced for FHC (K562^shFHC) comparing it with K562 transduced with scrambled RNA (K562^shRNA). Four miRNAs, namely hsa-let-7g, hsa-let-7f, hsa-let-7i and hsa-miR-125b, were significantly up-regulated in silenced cells. The remarkable down-regulation of these miRNAs, following FHC expression rescue, supports a specific relation between FHC silencing and miRNA-modulation. The integration of target predictions with miRNA and gene expression profiles led to the identification of a regulatory network which includes the miRNAs up-regulated by FHC silencing, as well as91 down-regulated putative target genes. These genes were further classified in 9 networks; the highest scoring network, “Cell Death and Survival, Hematological System Development and Function, Hematopoiesis”, is composed by 18 focus molecules including RAF1 and ERK1/2. We confirmed that, following FHC silencing, ERK1/2 phosphorylation is severely impaired and that RAF1 mRNA is significantly down-regulated. Taken all together, our data indicate that, in our experimental model, FHC silencing may affect RAF1/pERK1/2 levels through the modulation of a specific set of miRNAs and add new insights in to the relationship among iron homeostasis and miRNAs.     

Is That Me or My Twin? Lack of Self-Face Recognition Advantage in Identical Twins

Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One’s own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin’s face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multisensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment.     

Increased T Regulatory Cells Are Associated with Adverse Clinical Features and Predict Progression in Multiple Myeloma

Background

Regulatory T (Treg) cells play an important role in the maintenance of immune system homeostasis. Multiple myeloma (MM) is a plasma cell disorder frequently associated with impaired immune cell numbers and functions.

Methods

We analyzed Treg cells in peripheral blood (n = 207) and bone marrow (n = 202) of pre-malignant and malignant MM patients using flow cytometry. Treg cells and their subsets from MM patients and healthy volunteers were functionally evaluated for their suppressive property. A cohort of 25 patients was analyzed for lymphocytes, CD4 T cells and Treg cells before and after treatment with cyclophosphamide, thalidomide plus dexamethasone (CTD).

Results

We found elevated frequencies of Treg cells in newly diagnosed (P<0.01) and relapsed MM patients (P<0.0001) compared to healthy volunteers. Also, Treg subsets including naïve (P = 0.015) and activated (P = 0.036) Treg cells were significantly increased in MM patients compared to healthy volunteers. Functional studies showed that Treg cells and their subsets from both MM and healthy volunteers were similar in their inhibitory function. Significantly increased frequencies of Treg cells were found in MM patients with adverse clinical features such as hypercalcemia (>10 mg/dL), decreased normal plasma cell (≤5%) count and IgA myeloma subtype. We also showed that MM patients with ≥5% of Treg cells had inferior time to progression (TTP) (13 months vs. median not reached; P = 0.013). Furthermore, we demonstrated the prognostic value of Treg cells in prediction of TTP by Cox regression analysis (P = 0.045). CTD treatment significantly reduced frequencies of CD4 T cells (P = 0.001) and Treg cells (P = 0.018) but not Treg cells/CD4 T cells ratio compared to pre-treatment.

Conclusions

Our study showed immune deregulation in MM patients which is evidenced by elevated level of functionally active Treg cells and patients with increased Treg cells have higher risk of progression.     

A New Real-Time PCR for the Detection of Plasmodium ovale wallikeri

It has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasites: P. ovale curtisi and P. ovale wallikeri. We have extended and optimized a Real-time PCR assay targeting the parasite’s small subunit ribosomal RNA (ssrRNA) gene to detect both these species. When the assay was applied to 31 archival blood samples from patients diagnosed with P. ovale, it was found that the infection in 20 was due to P. ovale curtisi and in the remaining 11 to P. ovale wallikeri. Thus, this assay provides a useful tool that can be applied to epidemiological investigations of the two newly recognized distinct P. ovale species, that might reveal if these species also differ in their clinical manifestation, drugs susceptibility and relapse periodicity. The results presented confirm that P. ovale wallikeri is not confined to Southeast Asia, since the majority of the patients analyzed in this study had acquired their P. ovale infection in African countries, mostly situated in West Africa.