Biogeography and species delimitation of the rheophilic suckermouth catfish genus Pseudolithoxus (Siluriformes: Loricariidae), with the description of a new species from the Brazilian Amazon

The rapids-dwelling suckermouth catfish genus Pseudolithoxus was previously only known from the Guiana-Shield-draining Orinoco and Casiquiare river systems of Colombia and Venezuela, but new records have expanded this range considerably further into the Amazon basin of Brazil, and include occurrences from rivers draining the northern Brazilian Shield. These highly disjunct records are now placed in an evolutionary and phylogeographic context using a dated species tree constructed from mitochondrial (Cytb) and nuclear (RAG1) gene sequence data. Due to mito-nuclear discordance, we also delimit the putative species using statistical coalescent models and a range of additional metrics. We infer that at least two species of Pseudolithoxus are present in the Amazon basin: P. nicoi, previously only recorded from the río Casiquiare, but now also reported from the upper rio Negro, and a new species, which we describe herein from south-draining Guiana Shield and north-draining Brazilian Shield. Our data reject a simple model of Miocene vicariance in the group following uplift of the Uaupés Arch separating the Orinoco and Amazon systems, and instead suggest more complex dispersal scenarios through palaeo-connections in the Pliocene and also via the contemporary rio Negro and rio Madeira in the late Pleistocene.

www.zoobank.org/urn:lsid:zoobank.org:pub:46A6BEC1-1A1B-4244-80-A6-FD9CF8DA0384.     

Pollen load diversity and foraging niche overlap in a pollinator community of the rare <Emphasis Type="Italic">Dictamnus albus</Emphasis> L.

Bees collect pollen as an important resource for offspring development while acting as pollen vectors for the plants visited. Foraging preferences of pollinators together with plant species availability shape the web of interactions at the local scale. In this study, we focused on the bee pollinator community of a population of the rare protected perennial herb Dictamnus albus, with the aim to characterise the pollen preferences and the foraging niche overlap among species through time. Bees were sampled during four consecutive years in a natural population of D. albus, throughout the blooming period of the plant species. We performed an analysis of insect pollen loads to investigate the interactions with the study species and the co-flowering plants in the area, and to evaluate the degree of foraging overlap among pollinators. Over the study years, all bee species showed a high fidelity to D. albus (60–80%), even if some taxa preferentially collected pollen from other flowering species. The foraging niche overlap in the pollinator community decreased together with an increased diversity of co-flowering plant species. The results obtained indicate that bees preferentially forage on D. albus in the studied area, but that co-flowering species contribute to complement their diet and likely reduce competition for foraging resources. It appears therefore important to maintain a high diversity of co-flowering plants to preserve the diversity in the studied pollinator community of D. albus.     

Quantifying compartment‐associated variations of protein abundance in proteomics data

Quantitative mass spectrometry enables to monitor the abundance of thousands of proteins across biological conditions. Currently, most data analysis approaches rely on the assumption that the majority of the observed proteins remain unchanged across compared samples. Thus, gross morphological differences between cell states, deriving from, e.g., differences in size or number of organelles, are often not taken into account. Here, we analyzed multiple published datasets and frequently observed that proteins associated with a particular cellular compartment collectively increase or decrease in their abundance between conditions tested. We show that such effects, arising from underlying morphological differences, can skew the outcome of differential expression analysis. We propose a method to detect and normalize morphological effects underlying proteomics data. We demonstrate the applicability of our method to different datasets and biological questions including the analysis of sub‐cellular proteomes in the context of Caenorhabditis elegans aging. Our method provides a complementary perspective to classical differential expression analysis and enables to uncouple overall abundance changes from stoichiometric variations within defined group of proteins.     

Spheroids from adipose‐derived stem cells exhibit an miRNA profile of highly undifferentiated cells

Two‐dimensional (2D) cell cultures have been extensively used to investigate stem cell biology, but new insights show that the 2D model may not properly represent the potential of the tissue of origin. Conversely, three‐dimensional cultures exhibit protein expression patterns and intercellular junctions that are more representative of their in vivo condition. Multiclonal cells that grow in suspension are defined as “spheroids,” and we have previously demonstrated that spheroids from adipose‐derived stem cells (S‐ASCs) displayed enhanced regenerative capability. With the current study, we further characterized S‐ASCs to further understand the molecular mechanisms underlying their stemness properties. Recent studies have shown that microRNAs (miRNAs) are involved in many cellular mechanisms, including stemness maintenance and proliferation, and adipose stem cell differentiation. Most studies have been conducted to identify a specific miRNA profile on adherent adipose stem cells, although little is still known about S‐ASCs. In this study, we investigate for the first time the miRNA expression pattern in S‐ASCs compared to that of ASCs, demonstrating that cell lines cultured in suspension show a typical miRNA expression profile that is closer to the one reported in induced pluripotent stem cells. Moreover, we have analyzed miRNAs that are specifically involved in two distinct moments of each differentiation, namely early and late stages of osteogenic, adipogenic, and chondrogenic lineages during long‐term in vitro culture. The data reported in the current study suggest that S‐ASCs have superior stemness features than the ASCs and they represent the true upstream stem cell fraction present in adipose tissue, relegating their adherent counterparts.     

How Nucleus Mechanics and ECM Microstructure Influence the Invasion of Single Cells and Multicellular Aggregates

In order to move in a three-dimensional extracellular matrix, the nucleus of a cell must squeeze through the narrow spacing among the fibers and, by adhering to them, the cell needs to exert sufficiently strong traction forces. If the nucleus is too stiff, the spacing too narrow, or traction forces too weak, the cell is not able to penetrate the network. In this article, we formulate a mathematical model based on an energetic approach, for cells entering cylindrical channels composed of extracellular matrix fibers. Treating the nucleus as an elastic body covered by an elastic membrane, the energetic balance leads to the definition of a necessary criterion for cells to pass through the regular network of fibers, depending on the traction forces exerted by the cells (or possibly passive stresses), the stretchability of the nuclear membrane, the stiffness of the nucleus, and the ratio of the pore size within the extracellular matrix with respect to the nucleus diameter. The results obtained highlight the importance of the interplay between mechanical properties of the cell and microscopic geometric characteristics of the extracellular matrix and give an estimate for a critical value of the pore size that represents the physical limit of migration and can be used in tumor growth models to predict their invasive potential in thick regions of ECM.     

Changing the site energy of per-614 in the Peridinin-chlorophyll a-protein does not alter its capability of chlorophyll triplet quenching

The peridinin–chlorophyll-a protein (PCP) is a water-soluble light harvesting protein of the dinoflagellate Amphidinium carterae, employing peridinin (Per) as the main carotenoid to fulfil light harvesting and photo-protective functions. Per molecules bound to the protein experience specific molecular surroundings which lead to different electronic and spectral properties. In the refolded N89?L variant PCP (N89?L-RFPCP) a significant part of the intensity on the long wavelength side of the absorption spectrum is shifted to shorter wavelengths due to a significant change in the Per-614 site energy. Since Per-614 has been shown to be the main chlorophyll (Chl) triplet quencher in the protein, and the relative geometry of pigments is not affected by the mutation as verified by X-ray crystallography, this variant is ideally suited to study the dependence of the triplet-triplet energy transfer (TTET) mechanism on the pigment site energy. By using a combination of Optically Detected Magnetic Resonance (ODMR), pulse Electron Paramagnetic Resonance (EPR) and Electron Nuclear DOuble Resonance (ENDOR) we found that PCP maintains the efficient Per-614-to-Chl-a TTET despite the change of Per-614 local energy. This shows the robustness of the photoprotective site, which is very important for the protection of the system.     

Fatal primary diffuse large B‐cell lymphoma of the maxillary sinus initially treated as an infectious disease in an elderly patient: A clinicopathologic report

Objective

To report a case of primary diffuse large B‐cell lymphoma (DLBCL) of the maxillary sinus in an 82‐year‐old Caucasian woman.

Background

Diffuse large B‐cell lymphoma of the maxillary sinus has non‐specific signs and symptoms that may be confused with benign inflammatory conditions and upper respiratory infections.

Methods

An incisional biopsy was performed. CD20⁺/CD3^–/Ki‐67: 95% cells were observed.

Conclusion

A good medical history, clinical and imaging evaluations and immunohistochemical reactions are crucial to establish a correct and early diagnosis of DLBCL.     

Moral Publics: Human Trafficking,Video Films and the Responsibility of the Postcolonial Subject

This article analyzes the ways in which a Nigerian video film about human trafficking is received by Nigerian women who have themselves experienced trafficking in their migration to Italy. This contextualized case study is used as a methodological “lockpick” to open up new lines of enquiry into the relationship that southern Nigerian video films create with their audiences. The essay argues that, by virtue of their specific “addressivity,” the genre of Nigerian video films that focus on female migration and prostitution participates in the creation of moral publics that are concerned with the definition of the postcolonial subject’s responsibility in shaping his/her own destiny.