Biopolymers Used for Receptor Immobilization for Nickel-Detection Biosensors in Food.

Food is humans' main source of nickel intake, which is responsible for the prevalence of allergic contact dermatitis and other pathological afflictions. While robust, the classical methods for nickel detection-atomic absorption spectrometry and inductively coupled plasma mass spectrometry-are expensive and laborious; in contrast, modern methods that utilize sensors-of which most are electrochemical-have rapid run times, are cost-effective, and are easily assembled. Here, we describe the use of four biopolymers (alginate, agar, chitosan, and carrageenan) for receptor immobilization on biosensors to detect nickel ions and use an optimization approach with three biopolymer concentrations to assay analytical performance profiles. We measured the total performance of screen-printed carbon electrodes immobilized with the biopolymer-sensor combinations using cyclic voltammetry (CV). Voltammetric behavior favored the carrageenan biosensor, based on performance characteristics measured using CV, with sensitivities of 2.68 (for 1% biopolymer concentration) and 2.08 (for 0.5% biopolymer concentration). Our results indicated that among the four biopolymer combinations, carrageenan with urease affixed to screen-printed electrodes was effective at coupling for nickel detection.

Global Challenges to Public Health Care Systems during the COVID-19 Pandemic: A Review of Pandemic Measures and Problems.

Beginning in December 2019, the world faced a critical new public health stressor with the emergence of SARS-CoV-2. Its spread was extraordinarily rapid, and in a matter of weeks countries across the world were affected, notably in their ability to manage health care needs. While many sectors of public structures were impacted by the pandemic, it particularly highlighted shortcomings in medical care infrastructures around the world that underscored the need to reorganize medical systems, as they were vastly unprepared and ill-equipped to manage a pandemic and simultaneously provide general and specialized medical care. This paper presents modalities in approaches to the pandemic by various countries, and the triaged reorganization of medical sections not considered first-line in the pandemic that was in many cases transformed into wards for treating COVID-19 cases. As new viruses and structural variants emerge, it is important to find solutions to streamline medical care in hospitals, which includes the expansion of digital network medicine (i.e., telemedicine and mobile health apps) for patients to continue to receive appropriate care without risking exposure to contagions. Mobile health app development continues to evolve with specialized diagnostics capabilities via external attachments that can provide rapid information sharing between patients and care providers while eliminating the need for office visits. Telemedicine, still in the early stages of adoption, especially in the developing world, can ensure access to medical information and contact with care providers, with the potential to release emergency rooms from excessive cases, and offer multidisciplinary access for patients and care providers that can also be a means to avoid contact during a pandemic. As this pandemic illustrated, an overhaul to streamline health care is essential, and a move towards greater use of mobile health and telemedicine will greatly benefit public health to control the spread of new variants and future outbreaks.

Development, Optimization, Characterization, and Application of Electrochemical Biosensors for Detecting Nickel Ions in Food.

Nickel is naturally present in drinking water and many dietary items, which expose the general population to nickel ingestion. This heavy metal can have a variety of harmful health effects, causing allergies and skin disorders (i.e., dermatitis), lung, cardiovascular, and kidney diseases, and even certain cancers; therefore, nickel detection is important for public health. Recent innovations in the development of biosensors have demonstrated they offer a powerful new approach over conventional analytical techniques for the identification and quantification of user-defined compounds, including heavy metals such as nickel. We optimized five candidate nickel-biosensing receptors, and tested each for efficiency of binding to immobilization elements on screen-printed electrodes (SPEs). We characterized the application of nickel-detecting biosensors with four different cultivated vegetables. We analyzed the efficiency of each nickel-detecting biosensor by potentiostat and atomic absorption spectrometry and compared the results from the sample analytes. We then analyzed the performance characteristics and responses of assembled biosensors, and show they are very effective at measuring nickel ions in food, especially with the urease-alginate biosensor affixed to silver SPEs, measured by cyclic voltammetry (sensitivity-2.1921 µA Mm-1 cm-2 and LOD-0.005 mg/L). Given the many advantages of biosensors, we describe an optimization pipeline approach to the application of different nickel-binding biosensors for public health, nutrition, and consumer safety, which are very promising.

Changes in Dietary Patterns and Clinical Health Outcomes in Different Countries during the SARS-CoV-2 Pandemic.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to an excess in community mortality across the globe. We review recent evidence on the clinical pathology of COVID-19, comorbidity factors, immune response to SARS-CoV-2 infection, and factors influencing infection outcomes. The latter specifically includes diet and lifestyle factors during pandemic restrictions. We also cover the possibility of SARS-CoV-2 transmission through food products and the food chain, as well as virus persistence on different surfaces and in different environmental conditions, which were major public concerns during the initial days of the pandemic, but have since waned in public attention. We discuss useful measures to avoid the risk of SARS-CoV-2 spread through food, and approaches that may reduce the risk of contamination with the highly contagious virus. While hygienic protocols are required in food supply sectors, cleaning, disinfection, avoidance of cross-contamination across food categories, and foodstuffs at different stages of the manufacturing process are still particularly relevant because the virus persists at length on inert materials such as food packaging. Moreover, personal hygiene (frequent washing and disinfection), wearing gloves, and proper use of masks, clothes, and footwear dedicated to maintaining hygiene, provide on-site protections for food sector employees as well as supply chain intermediates and consumers. Finally, we emphasize the importance of following a healthy diet and maintaining a lifestyle that promotes physical well-being and supports healthy immune system function, especially when government movement restrictions ("lockdowns") are implemented.

Opsin clines in butterflies suggest novel roles for insect photopigments.

Opsins are ancient molecules that enable animal vision by coupling to a vitamin-derived chromophore to form light-sensitive photopigments. The primary drivers of evolutionary diversification in opsins are thought to be visual tasks related to spectral sensitivity and color vision. Typically, only a few opsin amino acid sites affect photopigment spectral sensitivity. We show that opsin genes of the North American butterfly Limenitis arthemis have diversified along a latitudinal cline, consistent with natural selection due to environmental factors. We sequenced single nucleotide (SNP) polymorphisms in the coding regions of the ultraviolet (UVRh), blue (BRh), and long-wavelength (LWRh) opsin genes from ten butterfly populations along the eastern United States and found that a majority of opsin SNPs showed significant clinal variation. Outlier detection and analysis of molecular variance indicated that many SNPs are under balancing selection and show significant population structure. This contrasts with what we found by analysing SNPs in the wingless and EF-1 alpha loci, and from neutral amplified fragment length polymorphisms, which show no evidence of significant locus-specific or genome-wide structure among populations. Using a combination of functional genetic and physiological approaches, including expression in cell culture, transgenic Drosophila, UV-visible spectroscopy, and optophysiology, we show that key BRh opsin SNPs that vary clinally have almost no effect on spectral sensitivity. Our results suggest that opsin diversification in this butterfly is more consistent with natural selection unrelated to spectral tuning. Some of the clinally varying SNPs may instead play a role in regulating opsin gene expression levels or the thermostability of the opsin protein. Lastly, we discuss the possibility that insect opsins might have important, yet-to-be elucidated, adaptive functions in mediating animal responses to abiotic factors, such as temperature or photoperiod.

Ancient homology underlies adaptive mimetic diversity across butterflies.

Convergent evolution provides a rare, natural experiment with which to test the predictability of adaptation at the molecular level. Little is known about the molecular basis of convergence over macro-evolutionary timescales. Here we use a combination of positional cloning, population genomic resequencing, association mapping and developmental data to demonstrate that positionally orthologous nucleotide variants in the upstream region of the same gene, WntA, are responsible for parallel mimetic variation in two butterfly lineages that diverged >65 million years ago. Furthermore, characterization of spatial patterns of WntA expression during development suggests that alternative regulatory mechanisms underlie wing pattern variation in each system. Taken together, our results reveal a strikingly predictable molecular basis for phenotypic convergence over deep evolutionary time.

Rapid diversification and not clade age explains high diversity in neotropical Adelpha butterflies.

Latitudinal gradients in species richness are among the most well-known biogeographic patterns in nature, and yet there remains much debate and little consensus over the ecological and evolutionary causes of these gradients. Here, we evaluated whether two prominent alternative hypotheses (namely differences in diversification rate or clade age) could account for the latitudinal diversity gradient in one of the most speciose neotropical butterfly genera (Adelpha) and its close relatives. We generated a multilocus phylogeny of a diverse group of butterflies in the containing tribe Limenitidini, which has both temperate and tropical representatives. Our results suggest there is no relationship between clade age and species richness that could account for the diversity gradient, but that instead it could be explained by a significantly higher diversification rate within the predominantly tropical genus Adelpha. An apparent early larval host-plant shift to Rubiaceae and other plant families suggests that the availability of new potential host plants probably contributed to an increase in diversification of Adelpha in the lowland Neotropics. Collectively, our results support the hypothesis that the equatorial peak in species richness observed within Adelpha is the result of increased diversification rate in the last 10-15 Myr rather than a function of clade age, perhaps reflecting adaptive divergence in response to the dramatic host-plant diversity found within neotropical ecosystems.

Landscape genetics of alpine Sierra Nevada salamanders reveal extreme population subdivision in space and time.

Quantifying the influence of the landscape on the genetic structure of natural populations remains an important empirical challenge, particularly for poorly studied, ecologically cryptic species. We conducted an extensive microsatellite analysis to examine the population genetics of the southern long-toed salamander (Ambystoma macrodactylum sigillatum) in a naturally complex landscape. Using spatially explicit modelling, we investigated the influence of the Sierra Nevada topography on potential dispersal corridors between sampled populations. Our results indicate very high-genetic divergence among populations, high within-deme relatedness, and little evidence of recent migration or population admixture. We also discovered unexpectedly high between-year genetic differentiation (F(ST)) for breeding sites, suggesting that breeding groups vary over localized space and time. While environmental factors associated with high-elevation montane habitats apparently play an important role in shaping population differentiation, additional, species-specific biological processes must also be operating to account for observed deviations from temporal, among-year panmixia. Our study emphasizes the population-level insights that can be gained from high-density sampling in space and time, and the highly substructured population biology that may characterize amphibians in extreme montane habitats.

Range-wide genetic differentiation among North American great gray owls (Strix nebulosa) reveals a distinct lineage restricted to the Sierra Nevada, California.

Investigations of regional genetic differentiation are essential for describing phylogeographic patterns and informing management efforts for species of conservation concern. In this context, we investigated genetic diversity and evolutionary relationships among great gray owl (Strix nebulosa) populations in western North America, which includes an allopatric range in the southern Sierra Nevada in California. Based on a total dataset consisting of 30 nuclear microsatellite DNA loci and 1938-base pairs of mitochondrial DNA, we found that Pacific Northwest sampling groups were recovered by frequency and Bayesian analyses of microsatellite data and each population sampled, except for western Canada, showed evidence of recent population bottlenecks and low effective sizes. Bayesian and maximum likelihood phylogenetic analyses of sequence data indicated that the allopatric Sierra Nevada population is also a distinct lineage with respect to the larger species range in North America; we suggest a subspecies designation for this lineage should be considered (Strix nebulosa yosemitensis). Our study underscores the importance of phylogeographic studies for identifying lineages of conservation concern, as well as the important role of Pleistocene glaciation events in driving genetic differentiation of avian fauna.

Landscape genetics and least-cost path analysis reveal unexpected dispersal routes in the California tiger salamander (Ambystoma californiense).

A major goal of landscape genetics is to understand how landscapes structure genetic variation in natural populations. However, landscape genetics still lacks a framework for quantifying the effects of landscape features, such as habitat type, on realized gene flow. Here, we present a methodology for identifying the costs of dispersal through different habitats for the California tiger salamander (Ambystoma californiense), an endangered species restricted to grassland/vernal pool habitat mosaics. We sampled larvae from all 16 breeding ponds in a geographically restricted area of vernal pool habitat at the Fort Ord Natural Reserve, Monterey County, California. We estimated between-pond gene flow using 13 polymorphic microsatellite loci and constructed GIS data layers of habitat types in our study area. We then used least-cost path analysis to determine the relative costs of movement through each habitat that best match rates of gene flow measured by our genetic data. We identified four measurable rates of gene flow between pairs of ponds, with between 10.5% and 19.9% of larvae having immigrant ancestry. Although A. californiense is typically associated with breeding ponds in grassland habitat, we found that dispersal through grassland is nearly twice as costly as dispersal through chaparral and that oak woodland is by far the most costly habitat to traverse. With the increasing availability of molecular resources and GIS data, we anticipate that these methods could be applied to a broad range of study systems, particularly those with cryptic life histories that make direct observation of movement challenging.

A single origin of Batesian mimicry among hybridizing populations of admiral butterflies (Limenitis arthemis) rejects an evolutionary reversion to the ancestral phenotype.

Batesian mimicry is a fundamental example of adaptive phenotypic evolution driven by strong natural selection. Given the potentially dramatic impacts of selection on individual fitness, it is important to understand the conditions under which mimicry is maintained versus lost. Although much empirical and theoretical work has been devoted to the maintenance of Batesian mimicry, there are no conclusive examples of its loss in natural populations. Recently, it has been proposed that non-mimetic populations of the polytypic Limenitis arthemis species complex represent an evolutionary loss of Batesian mimicry, and a reversion to the ancestral phenotype. Here, we evaluate this conclusion using segregating amplified fragment length polymorphism markers to investigate the history and fate of mimicry among forms of the L. arthemis complex and closely related Nearctic Limenitis species. In contrast to the previous finding, our results support a single origin of mimicry within the L. arthemis complex and the retention of the ancestral white-banded form in non-mimetic populations. Our finding is based on a genome-wide sampling approach to phylogeny reconstruction that highlights the challenges associated with inferring the evolutionary relationships among recently diverged species or populations (i.e. incomplete lineage sorting, introgressive hybridization and/or selection).

Historical isolation, range expansion, and secondary contact of two highly divergent mitochondrial lineages in spotted salamanders (Ambystoma maculatum).

The high species diversity of aquatic and terrestrial faunas in eastern North America has been attributed to range reductions and allopatric diversification resulting from historical climate change. The role these processes may have played in speciation is still a matter of considerable debate; however, their impacts on intraspecific genetic structure have been well documented. We use mitochondrial DNA sequences to reconstruct an intraspecific phylogeny of the widespread North American spotted salamander, Ambystoma maculatum, and test whether phylogenetic patterns conform to regional biogeographical hypotheses about the origins of diversity in eastern North America. Specifically, we address the number and locations of historical refugia, the extent and patterns of postglacial colonization by divergent lineages, and the origin and affinities of populations in the Interior Highland region. Despite apparent morphological uniformity, genetic discontinuities throughout the range of this species suggest that populations were historically fragmented in at least two refugia in the southern Appalachian Mountains. The ranges of these two highly divergent clades expanded northward, resulting in two widely distributed lineages that are sympatric in regions previously proposed as suture zones for other taxa. The evolutionary history of spotted salamander populations underscores the generality of biogeographical processes in eastern North America: despite differences in population size, glacial refugia, and vagility, similar signatures of differentiation are evident among and within widespread taxa.

Lethal and sublethal effects of polychlorinated biphenyls on Rana sylvatica tadpoles.

In static experiments, we exposed tadpoles of the wood frog (Rana sylvatica) to sediment collected from a riverine wetland in the St. Lawrence River basin that is highly contaminated with polychlorinated biphenyls (PCBs). Significant mortality occurred early in the experiment and was not explained by a simple dose-dependent relationship. Direct sediment contact resulted in higher tadpole mortality compared with tadpoles suspended in mesh containers above the sediment. Sublethal effects of exposure were also apparent, characterized by behavioral abnormalities, including reduced activity levels and swimming speed, that differed depending on whether tadpoles were in contact with or suspended above the sediment. We demonstrate in this experiment that PCB-contaminated sediment induced significant mortality and behavioral dysfunction in early development, but the effects on natural populations existing in the contaminated region is not known.