Both Hoxc13 orthologs are functionally important for zebrafish tail fin regeneration

Hox genes are re-expressed during regeneration in many species. Given their important role in body plan development, it has been assumed, but not directly shown, that they play a functional role in regeneration. In this paper we show that morpholino-mediated knockdown of either Hoxc13a or Hoxc13b during the process of zebrafish tail fin regeneration results in a significant reduction of regenerative outgrowth. Furthermore, cellular proliferation within the blastema is directly affected in both knockdowns. Hence, similar to the demonstration of unique functions of multiple Hox genes during limb formation, both Hoxc13 orthologs have distinct functions in regeneration.     

Stopping azithromycin mass drug administration for trachoma: A systematic review

The World Health Organization (WHO) recommends continuing azithromycin mass drug administration (MDA) for trachoma until endemic regions drop below 5% prevalence of active trachoma in children aged 1–9 years. Azithromycin targets the ocular strains of Chlamydia trachomatis that cause trachoma. Regions with low prevalence of active trachoma may have little if any ocular chlamydia, and, thus, may not benefit from azithromycin treatment. Understanding what happens to active trachoma and ocular chlamydia prevalence after stopping azithromycin MDA may improve future treatment decisions. We systematically reviewed published evidence for community prevalence of both active trachoma and ocular chlamydia after cessation of azithromycin distribution. We searched electronic databases for all peer-reviewed studies published before May 2020 that included at least 2 post-MDA surveillance surveys of ocular chlamydia and/or the active trachoma marker, trachomatous inflammation–follicular (TF) prevalence. We assessed trends in the prevalence of both indicators over time after stopping azithromycin MDA. Of 140 identified studies, 21 met inclusion criteria and were used for qualitative synthesis. Post-MDA, we found a gradual increase in ocular chlamydia infection prevalence over time, while TF prevalence generally gradually declined. Ocular chlamydia infection may be a better measurement tool compared to TF for detecting trachoma recrudescence in communities after stopping azithromycin MDA. These findings may guide future trachoma treatment and surveillance efforts.     

Clinal variation or validation of a subspecies? A case study of the Graptemys nigrinoda complex (Testudines: Emydidae)

Widely distributed species often display intraspecific morphological variation due to the abiotic and biotic gradients experienced across their ranges. Historically, in many vertebrate taxa, such as birds and reptiles, these morphological differences within a species were used to delimit subspecies. Graptemys nigrinoda is an aquatic turtle species endemic to the Mobile Bay Basin. Colour pattern and morphological variability were used to describe a subspecies (G. n. delticola) from the lower reaches of the system, although it and the nominate subspecies also reportedly intergrade over a large portion of the range. Other researchers have suggested that these morphological differences merely reflect clinal variation. Our molecular data (mtDNA) did not support the existence of the subspecies, as the haplotypes were differentiated by only a few base pairs and one haplotype was shared between the putative subspecies. While there were significant morphological and pattern differences among putative specimens of G. n. nigrinoda, G. n. delticola and G. n. nigrinoda × delticola, these differences probably represent clinal variation as they were also related to environmental variables [i.e. cumulative drainage area and drainage (categorical)]. Specimens occupying slow‐current, high‐turbidity river reaches (e.g. the Tensaw River) exhibited greater relative carapace heights and more dark pigmentation, while specimens occupying fast‐current, clearer rivers (e.g. the upper Alabama, Cahaba and Tallapoosa rivers) exhibited lower carapace heights and more yellow pigmentation. Given the absence of clear molecular and morphological differences that are related to drainage characteristics, we suggest that there is not sufficient evidence for the recognition of G. n. delticola as a distinct subspecies. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 810–822.     

The Macroecology of Airborne Pollen in Australian and New Zealand Urban Areas

The composition and relative abundance of airborne pollen in urban areas of Australia and New Zealand are strongly influenced by geographical location, climate and land use. There is mounting evidence that the diversity and quality of airborne pollen is substantially modified by climate change and land-use yet there are insufficient data to project the future nature of these changes. Our study highlights the need for long-term aerobiological monitoring in Australian and New Zealand urban areas in a systematic, standardised, and sustained way, and provides a framework for targeting the most clinically significant taxa in terms of abundance, allergenic effects and public health burden.     

The biological chemistry of lead

Recent biophysical studies on the interactions between lead and recombinant proteins and peptides that naturally bind zinc or calcium have provided unparalleled insights into the biological chemistry and molecular toxicology of lead. These studies lay the foundation for the rational design of improved methods for detecting and treating lead poisoning.     

An abundant tissue macrophage population in the adult murine heart with a distinct alternatively-activated macrophage profile

Cardiac tissue macrophages (cTMs) are a previously uncharacterised cell type that we have identified and characterise here as an abundant GFP(+) population within the adult Cx(3)cr1(GFP/+) knock-in mouse heart. They comprise the predominant myeloid cell population in the myocardium, and are found throughout myocardial interstitial spaces interacting directly with capillary endothelial cells and cardiomyocytes. Flow cytometry-based immunophenotyping shows that cTMs exhibit canonical macrophage markers. Gene expression analysis shows that cTMs (CD45(+)CD11b(+)GFP(+)) are distinct from mononuclear CD45(+)CD11b(+)GFP(+) cells sorted from the spleen and brain of adult Cx(3)cr1(GFP/+) mice. Gene expression profiling reveals that cTMs closely resemble alternatively-activated anti-inflammatory M2 macrophages, expressing a number of M2 markers, including Mrc1, CD163, and Lyve-1. While cTMs perform normal tissue macrophage homeostatic functions, they also exhibit a distinct phenotype, involving secretion of salutary factors (including IGF-1) and immune modulation. In summary, the characterisation of cTMs at the cellular and molecular level defines a potentially important role for these cells in cardiac homeostasis.     

Site-specific PEGylation at histidine tags

The efficacy of protein-based medicines can be compromised by their rapid clearance from the blood circulatory system. Achieving optimal pharmacokinetics is a key requirement for the successful development of safe protein-based medicines. Protein PEGylation is a clinically proven strategy to increase the circulation half-life of protein-based medicines. One limitation of PEGylation is that there are few strategies that achieve site-specific conjugation of PEG to the protein. Here, we describe the covalent conjugation of PEG site-specifically to a polyhistidine tag (His-tag) on a protein. His-tag site-specific PEGylation was achieved with a domain antibody (dAb) that had a 6-histidine His-tag on the C-terminus (dAb-His(6)) and interferon α-2a (IFN) that had an 8-histidine His-tag on the N-terminus (His(8)-IFN). The site of PEGylation at the His-tag for both dAb-His(6)-PEG and PEG-His(8)-IFN was confirmed by digestion, chromatographic, and mass-spectral studies. A methionine was also inserted directly after the N-terminal His-tag in IFN to give His(8)Met-IFN. Cyanogen bromide digestion studies of PEG-His(8)Met-IFN were also consistent with PEGylation at the His-tag. By using increased stoichiometries of the PEGylation reagent, it was possible to conjugate two separate PEG molecules to the His-tag of both the dAb and IFN proteins. Stability studies followed by in vitro evaluation confirmed that these PEGylated proteins retained their biological activity. In vivo PK studies showed that all of the His-tag PEGylated samples displayed extended circulation half-lives. Together, our results indicate that site-specific, covalent PEG conjugation at a His-tag can be achieved and biological activity maintained with therapeutically relevant proteins.     

A recombinant courtship pheromone affects sexual receptivity in a plethodontid salamander

Pheromones are important chemical signals for many vertebrates, particularly during reproductive interactions. In the terrestrial salamander Plethodon shermani, a male delivers proteinaceous pheromones to the female as part of their ritualistic courtship behavior. These pheromones increase the female's receptivity to mating, as shown by a reduction in courtship duration. One pheromone component in particular is plethodontid receptivity factor (PRF), a 22-kDa protein with multiple isoforms. This protein alone can act as a courtship pheromone that causes the female to be more receptive. We used a bacterial expression system to synthesize a single recombinant isoform of PRF. The recombinant protein was identical to the native PRF, based on mass spectrometry, circular dichroism spectra, and a behavioral bioassay that tested the effects of recombinant PRF (rPRF) on female receptivity (21% reduction in courtship duration). The rPRF appears to mimic the activity of a mixture of PRF isoforms, as well as a mixture of multiple different proteins that comprise the male courtship gland extract. Pheromones that are peptides have been characterized for some vertebrates; to date, however, rPRF is one of only 2 synthesized vertebrate proteins to retain full biological activity.     

Oxidation of glucose by syntrophic association between <Emphasis Type="Italic">Geobacter</Emphasis> and hydrogenotrophic methanogens in microbial fuel cell

Objective

To investigate a syntrophic interaction between Geobacter sulfurreducens and hydrogenotrophic methanogens in sludge-inoculated microbial fuel cell (MFC) systems running on glucose with an improved electron recovery at the anode.

Results

The presence of archaea in MFC reduces Coulombic efficiency (CE) due to their electron scavenging capability but, here, we demonstrate that a syntrophic interaction can occur between G. sulfurreducens and hydrogenotrophic methanogens via interspecies H₂ transfer with improvement in CE and power density. The addition of the methanogenesis inhibitor, 2-bromoethanesulfonate (BES), resulted in the reduction in power density from 5.29 to 2 W/m³, and then gradually increased to the peak value of 5.5 W/m³ when BES addition was stopped.

Conclusion

Reduction of H₂ partial pressure by archaea is an efficient approach in improving power output in a glucose-fed MFC system using Geobacter sp. as an inoculum.

     

Reclamation and habitat‐disturbance effects on landbird abundance and productivity indices in the oil sands region of northeastern Alberta,Canada

The pace and scale of reclamation in Alberta's oil sands region are increasing, and techniques to measure and validate the ecological function of developing habitats are needed. In Alberta, achievement of equivalent land capability to that present before disturbance is a regulatory requirement of reclamation certification. We compared landbird abundance and productivity indices from mist‐netting data collected in 2011–2013 using the Monitoring Avian Productivity and Survivorship (MAPS) protocol with local habitat covariates at 35 monitoring stations in natural, reclaimed, and disturbed habitats. Principal component analysis of habitat covariates explained 83% of the variation in 20 habitat‐structure variables. We found significant relationships between habitat covariates and captures of adult birds, young birds, and/or the probability of capturing a young bird (productivity) for 12 landbird species; in some cases, capture responses contrasted with productivity responses to habitat variables. Responses to reclamation age were as expected, given habitat preferences of our target species. Positive responses to reclamation age from obligate forest‐dwelling species take more years to become evident than those for species preferring successional‐stage habitats, while one species that prefers open, grassland habitats appeared to decline with reclamation age, presumably due to habitat succession. Application of the MAPS protocol as a tool to evaluate and track the performance of reclaimed and disturbed habitats is demonstrated, with landbird abundance and productivity indices in natural habitats being useful indicators of equivalent land capability.