Characterization of Pallid Sturgeon (Scaphirhynchus albus) Spawning Habitat in the Lower Missouri River

Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species’ range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The objective of this study was to determine spawning locations and describe habitat characteristics and environmental conditions (depth, water velocity, substrate, discharge, temperature, and turbidity) on the Lower Missouri River. We measured habitat characteristics for spawning events of ten telemetry-tagged female pallid sturgeon from 2008–2013 that occurred in discrete reaches distributed over hundreds of kilometers. These results show pallid sturgeon select deep and fast areas in or near the navigation channel along outside revetted banks for spawning. These habitats are deeper and faster than nearby river habitats within the surrounding river reach. Spawning patches have a mean depth of 6.6 m and a mean depth-averaged water-column velocity of 1.4 m per second. Substrates in spawning patches consist of coarse bank revetment, gravel, sand, and bedrock. Results indicate habitat used by pallid sturgeon for spawning is more common and widespread in the present-day channelized Lower Missouri River relative to the sparse and disperse coarse substrates available prior to channelization. Understanding the spawning habitats currently utilized on the Lower Missouri River and if they are functioning properly is important for improving habitat remediation measures aimed at increasing reproductive success. Recovery efforts for pallid sturgeon on the Missouri River, if successful, can provide guidance to sturgeon recovery on other river systems; particularly large, regulated, and channelized rivers.     

Translational control of coronaviruses

Coronaviruses represent a large family of enveloped RNA viruses that infect a large spectrum of animals. In humans, the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic and is genetically related to SARS-CoV and Middle East respiratory syndrome-related coronavirus (MERS-CoV), which caused outbreaks in 2002 and 2012, respectively. All viruses described to date entirely rely on the protein synthesis machinery of the host cells to produce proteins required for their replication and spread. As such, virus often need to control the cellular translational apparatus to avoid the first line of the cellular defense intended to limit the viral propagation. Thus, coronaviruses have developed remarkable strategies to hijack the host translational machinery in order to favor viral protein production. In this review, we will describe some of these strategies and will highlight the role of viral proteins and RNAs in this process.     

Improvement in cyst recovery and molecular detection of Giardia duodenalis from stool samples

Molecular Biology Reports - Molecular detection of Giardia duodenalis by polymerase chain reaction (PCR) is difficult in faecal samples due to inhibitors that contaminate DNA preparations, or due...     

Mediator subunit MED1 modulates intranuclear dynamics of the thyroid hormone receptor

The thyroid hormone receptors (TRs) mediate thyroid hormone (T₃)-dependent gene expression. The nuclear import and export signals that direct TR shuttling are well characterized, but little is known about factors modulating nuclear retention. We used fluorescence-based nucleocytoplasmic scoring and fluorescence recovery after photobleaching in transfected cells to investigate whether Mediator subunits MED1 and MED13 play a role in nuclear retention of TR. When MED1 was overexpressed, there was a striking shift towards a greater nuclear localization of TRβ1 and the oncoprotein v-ErbA, subtypes with cytosolic populations at steady-state, and TRβ1 intranuclear mobility was reduced. For TRα1, there was no observable change in its predominantly nuclear distribution pattern or mobility. Consistent with a role for MED1 in nuclear retention, the cytosolic TRα1 and TRβ1 population were significantly greater in MED1^−/− cells, compared with MED1^+/+ cells. Exposure to T₃ and epidermal growth factor, which induces MED1 phosphorylation, also altered TR intranuclear dynamics. Overexpression of miR-208a, which downregulates MED13, led to a more cytosolic distribution of nuclear-localized TRα1; however, overexpression of MED13 had no effect on TRβ1 localization. The known binding site of MED1 overlaps with a transactivation domain and nuclear export signal in helix 12 of TR's ligand-binding domain (LBD). Coimmunoprecipitation assays demonstrated that TR's LBD interacts directly with exportins 5 and 7, suggesting that binding of exportins and MED1 to TR may be mutually exclusive. Collectively, our data provide evidence that MED1 promotes nuclear retention of TR, and highlight the dual functionality of helix 12 in TR transactivation and nuclear export.     

Programmable assembly of 2D crystalline protein arrays into covalently stacked 3D bionanomaterials

Rational embellishment of self-assembling two-dimensional (2D) proteins make it possible to build 3D nanomaterials with novel catalytic, optoelectronic and mechanical properties. However, introducing multiple sites of embellishment into 2D protein arrays without affecting the self-assembly is challenging, limiting the ability to program in additional functionality and new 3D configurations. Here we introduce two orthogonal covalent linkages at multiple sites in a 2D crystalline-forming protein without affecting its self-assembly. We first engineered the surface-layer protein SbsB from Geobacillus stearothermophilus pV72/p2 to display isopeptide bond-forming protein conjugation pairs, SpyTag or SnoopTag, at four positions spaced 5.7-10.5 nm apart laterally and 3 nm axially. The C-terminal and two newly-identified locations within SbsB monomer accommodated the short SpyTag or SnoopTag peptide tags without affecting the 2D lattice structure. Introducing tags at distinct locations enabled orthogonal and covalent binding of SpyCatcher- or SnoopCatcher-protein fusions to micron-sized 2D nanosheets. By introducing different types of bifunctional cross-linkers, the dual-functionalized nanosheets were programmed to self-assemble into different 3D stacks, all of which retain their nanoscale order. Thus, our work creates a modular protein platform that is easy to program to create dual-functionalized 2D and lamellar 3D nanomaterials with new catalytic, optoelectronic, and mechanical properties.     

A Case of Relapsed Chromoblastomycosis Due to Fonsecaea monophora: Antifungal Susceptibility and Phylogenetic Analysis

Chromoblastomycosis is a chronic cutaneous and subcutaneous mycosis. The management of this infection continues to be challenging because there is no consensus on the therapeutic regimen. We report here a case of a 69-year-old male patient with cauliflower-like lesions on his left leg and foot. He had already been treated with itraconazole at a dose of 200 mg/day for 5 months, with mycological cure for all the affected areas. However, the lesions relapsed at both sites, and treatment with itraconazole was resumed at the dose previously used. Initially, direct mycological examination, cultural, and microculture slide observation were performed. Afterward, sequencing of the ITS1-5.8S rDNA-ITS2 region of the fungal DNA and evaluation of its susceptibility to antifungal agents alone and in combination were performed. In direct mycological examination, the presence of sclerotic cells was verified, and the fungus was identified as Fonsecaea based on cultural and microscopic examinations. Identification as Fonsecaea monophora was confirmed after sequencing of the ITS region and phylogenetic analysis. The isolate was susceptible to itraconazole and terbinafine. The combinations of amphotericin B and terbinafine and terbinafine and voriconazole were synergistic. The use of drugs for which the causative agent is susceptible to singly or in combination may be an alternative for the treatment of mycosis. Furthermore, the identification of the agent by molecular techniques is important for epidemiological purposes. To the best of our knowledge, this is the first case of relapsed chromoblastomycosis caused by F. monophora in Brazil.