Evaluation of Viral Inactivation on Dry Surface by High Peak Power Microwave (HPPM) Exposure

Previous research has shown that virus infectivity can be dramatically reduced by radio frequency exposure in the gigahertz (GHz) frequency range. Given the worldwide SARS-CoV-2 pandemic, which has caused over 1 million deaths and has had a profound global economic impact, there is a need for a noninvasive technology that can reduce the transmission of virus among humans. RF is a potential wide area-of-effect viral decontamination technology that could be used in hospital rooms where patients are expelling virus, in grocery and convenience stores where local populations mix, and in first responder settings where rapid medical response spans many potentially infected locations within hours. In this study, we used bovine coronavirus (BCoV) as a surrogate of SARS-CoV-2 and exposed it to high peak power microwave (HPPM) pulses at four narrowband frequencies: 2.8, 5.6, 8.5, and 9.3 GHz. Exposures consisted of 2 µs pulses delivered at 500 Hz, with pulse counts varied by decades between 1 and 10,000. The peak field intensities (i.e. the instantaneous power density of each pulse) ranged between 0.6 and 6.5 MW/m², depending on the microwave frequency. The HPPM exposures were delivered to plastic coverslips containing BCoV dried on the surface. Hemagglutination (HA) and cytopathic effect analyses were performed 6 days after inoculation of host cells to assess viral infectivity. No change in viral infectivity was seen with increasing dose (pulse number) across the tested frequencies. Under all conditions tested, exposure did not reduce infectivity more than 1.0 log_10. For the conditions studied, high peak power pulsed RF exposures in the 2–10 GHz range appear ineffective as a virucidal approach for hard surface decontamination. © 2023 Bioelectromagnetics Society.     

French naiad (Bivalvia: Margaritiferidae,Unionidae) species distribution models: prediction maps as tools for conservation

The aim of this study was to determine whether juvenile scalloped hammerhead sharks (Sphyrna lewini) use the south-eastern Gulf of California as a nursery and feeding area. This information could help lay the groundwork required for the conservation of this endangered species. To address this, we carried out stable isotope (δ¹⁵N and δ¹³C) and stomach content analyses of sharks caught between 2000 and 2004 in Mazatlan, Mexico. Stomach contents and δ¹³C values indicated that S. lewini is a predator that feeds on benthic prey near the coast. Differences in δ¹⁵N average values between sizes classes (<100 vs. >100 cm) suggest that there was an ontogenetic change in this shark’s feeding habits and also in their living environment (from benthic areas to pelagic areas). The trophic position indicated that S. lewini is a tertiary consumer, but with a high degree of trophic plasticity, and thus, different trophic roles, highlighting the importance of this predator as a regulator of prey populations. Finally, the linear isotopic relationship between S. lewini and its prey indicates a long residency within the Mazatlan area. Our results demonstrate that the south-eastern Gulf of California is a nursery area that offers abundant food for juvenile scalloped hammerhead sharks.     

Spontaneous inflammatory cytokine gene expression in normal human peripheral blood mononuclear cells

Cytokines regulate cellular immune activity and are produced by a variety of cells, especially lymphocytes, monocytes, and macrophages. Measurement of cytokine levels has yielded useful information on the pathological process of different diseases such as AIDS, endotoxic shock, sepsis, asthma, and cancer. It may also be of use in the monitoring of disease progression and/or inflammation. To determine spontaneous cytokine gene expression in whole blood and PBMCs, whole blood was obtained from healthy volunteers and total mRNA was isolated from PBMCs. The kinetics of response were determined by sequential testing of cytokine gene expression by RT-PCR analysis. Our results demonstrated that isolated and incubated PBMCs expressed TNF-alpha and high levels of IL-1beta, IL-6, IL-8, and IL-10. In contrast, WB only expressed the mRNA cytokines of TNF-alpha and IL-8 (p < 0.05). These results suggest that spontaneous myriad mRNA cytokine expression can be avoided with the use of WB incubation and the rapid collection of PBMCs. Furthermore, this method should be employed in all cases where the levels of cytokine gene expression can be evaluated.     

Genes that encode botulism neurotoxins A, B, E and F in neotropical bee honey identified with the polymerase chain reaction

Honey can be used for the treatment of wounds, sores and skin bums, but it might be contaminated with Clostridium botulinum spores. In order to evaluate Costa Rican raw honey samples, the detection of neurotoxin gene sequences (corresponding to the bacterium) C. botulinum A, B, E and F was done with the polymerase chain reaction. A total of 64 raw honey samples, coming from different Costa Rican sites were analyzed. Reference C. botulinum strains type A (ATCC 19397), type B (ATCC 7949), type E (ATCC 17786) and type F (ATCC 25764) were used as templates for testing the effectivity of the method. The process consisted in culturing the honey samples in prereduced triptose-peptone-glucose-yeast extract media (TGPY) for 5 days. After this, the bacteria lysate obtained was used for PCR. The amplicons, product of the reaction, were visualized using agarose gel 2%. From the 64 honey samples analyzed, none produced positive results in the PCR, since no amplicons were obtained. Even though, all the reference C. botulinum strains used as controls were visualized and showed the effectivity of the extraction method and of the PCR used. The results obtained show promising therapeutic uses for honey from Costa Rica, but further evaluations shall be done in order to be sure of the safety of the product.     

SNaPaer: A Practical Single Nucleotide Polymorphism Multiplex Assay for Genotyping of Pseudomonas aeruginosa

Multilocus sequence typing (MLST) represents the gold standard genotyping method in studies concerning microbial population structure, being particularly helpful in the detection of clonal relatedness. However, its applicability on large-scale genotyping is limited due to the high cost and time spent on the task. The selection of the most informative nucleotide positions simplifies genomic characterization of bacteria. A simple and informative multiplex, SNaPaer assay, was developed and genotyping of Pseudomonas aeruginosa was obtained after a single reaction of multiplex PCR amplification and mini-sequencing. This cost-effective technique allowed the analysis of a Portuguese set of isolates (n = 111) collected from three distinct hospitals and the genotyping data could be obtained in less than six hours. Point mutations were shown to be the most frequent event responsible for diversification of the Portuguese population sample. The Portuguese isolates corroborated the epidemic hypothesis for P. aeruginosa population. SNaPaer genotyping assay provided a discriminatory power of 0.9993 for P. aeruginosa, by testing in silico several hundreds of MLST profiles available online. The newly proposed assay targets less than 0.01% of the total MLST length and guarantees reproducibility, unambiguous analysis and the possibility of comparing and transferring data between different laboratories. The plasticity of the method still supports the addition of extra molecular markers targeting specific purposes/populations. SNaPaer can be of great value to clinical laboratories by facilitating routine genotyping of P. aeruginosa.     

Genetic prediction of complex traits: integrating infinitesimal and marked genetic effects

Genetic prediction for complex traits is usually based on models including individual (infinitesimal) or marker effects. Here, we concentrate on models including both the individual and the marker effects. In particular, we develop a “Mendelian segregation” model combining infinitesimal effects for base individuals and realized Mendelian sampling in descendants described by the available DNA data. The model is illustrated with an example and the analyses of a public simulated data file. Further, the potential contribution of such models is assessed by simulation. Accuracy, measured as the correlation between true (simulated) and predicted genetic values, was similar for all models compared under different genetic backgrounds. As expected, the segregation model is worthwhile when markers capture a low fraction of total genetic variance.     

Molecular characterization of a novel Na+/H+ antiporter cDNA from Eucalyptus globulus

Environmental stress factors such as salt, drought and heat are known to affect plant productivity. However, high salinity is spreading throughout the world, currently affecting more than 45 million ha. One of the mechanisms that allow plants to withstand salt stress consists on vacuolar sequestration of Na⁺, through a Na⁺/H⁺ antiporter. We isolated a new vacuolar Na⁺/H⁺ antiporter from Eucalyptus globulus from a cDNA library. The cDNA had a 1626 bp open reading frame encoding a predicted protein of 542 amino acids with a deduced molecular weight of 59.1 KDa. Phylogenetic and bioinformatic analyses indicated that EgNHX1 localized in the vacuole. To assess its role in Na⁺ exchange, we performed complementation studies using the Na⁺ sensitive yeast mutant strain Δnhx1. The results showed that EgNHX1 partially restored the salt sensitive phenotype of the yeast Δnhx1 strain. However, its overexpression in transgenic Arabidopsis confers tolerance in the presence of increasing NaCl concentrations while the wild type plants exhibited growth retardation. Expression profiles of Eucalyptus seedlings subjected to salt, drought, heat and ABA treatment were established. The results revealed that Egnhx1 was induced significantly only by drought. Together, these results suggest that the product of Egnhx1 from E. globulus is a functional vacuolar Na⁺/H⁺ antiporter.