Growth and chemotaxis of nematodes reduced upon exposure to Third Fork Creek surface water

Background Third Fork Creek is a historically impaired urban stream that flows through the city of Durham, North Carolina. Caenorhabditis elegans (C. elegans) are non-parasitic, soil and aquatic dwelling nematodes that have been used frequently as a biological and ecotoxicity model. We hypothesize that exposure to Third Fork Creek surface water will inhibit the growth and chemotaxis of C. elegans. Using our ring assay model, nematodes were enticed to cross the water samples to reach a bacterial food source which allowed observation of chemotaxis. The total number of nematodes found in the bacterial food source and the middle of the plate with the water source was recorded for 3 days. Results Our findings suggest a reduction in chemotaxis and growth on day three in nematodes exposed to Third Fork Creek water samples when compared to the control (p value < 0.05). These exploratory data provide meaningful insight to the quality of Third Fork Creek located near a Historically Black University. Conclusions Further studies are necessary to elucidate the concentrations of the water contaminants and implications for human health. The relevance of this study lies within the model C. elegans that has been used in a plethora of human diseases and exposure research but can be utilized as an environmental indicator of water quality impairment.

Modulation of sensory perception by hydrogen peroxide enables Caenorhabditis elegans to find a niche that provides both food and protection from hydrogen peroxide

Hydrogen peroxide (H2O2) is the most common chemical threat that organisms face. Here, we show that H2O2 alters the bacterial food preference of Caenorhabditis elegans, enabling the nematodes to find a safe environment with food. H2O2 induces the nematodes to leave food patches of laboratory and microbiome bacteria when those bacterial communities have insufficient H2O2-degrading capacity. The nematode’s behavior is directed by H2O2-sensing neurons that promote escape from H2O2 and by bacteria-sensing neurons that promote attraction to bacteria. However, the input for H2O2-sensing neurons is removed by bacterial H2O2-degrading enzymes and the bacteria-sensing neurons’ perception of bacteria is prevented by H2O2. The resulting cross-attenuation provides a general mechanism that ensures the nematode’s behavior is faithful to the lethal threat of hydrogen peroxide, increasing the nematode’s chances of finding a niche that provides both food and protection from hydrogen peroxide.

Modulation of sensory perception by hydrogen peroxide enables Caenorhabditis elegans to find a niche that provides both food and protection from hydrogen peroxide

SummaryHydrogen peroxide (H2O2) is the most common chemical threat that organisms face. Here, we show that H2O2 alters the bacterial food preference of Caenorhabditis elegans, enabling the nematodes to find a safe environment with food. H2O2 induces the nematodes to leave food patches of laboratory and microbiome bacteria when those bacterial communities have insufficient H2O2-degrading capacity. The nematode’s behavior is directed by H2O2-sensing neurons that promote escape from H2O2 and by bacteria-sensing neurons that promote attraction to bacteria. However, the input for H2O2-sensing neurons is removed by bacterial H2O2-degrading enzymes and the bacteria-sensing neurons’ perception of bacteria is prevented by H2O2. The resulting cross-attenuation provides a general mechanism that ensures the nematode’s behavior is faithful to the lethal threat of hydrogen peroxide, increasing the nematode’s chances of finding a niche that provides both food and protection from hydrogen peroxide.

Using Caenorhabditis Elegans As An Environmental Indicator for Impaired Urbanized Watersheds

Background Third Fork Creek is a historically impaired urban stream that flows through the city of Durham, North Carolina. Caenorhabditis elegans (C. elegans) are non-parasitic, soil and aquatic dwelling nematodes that have been used frequently as a biological and ecotoxicity model. We hypothesize that exposure to Third Fork Creek surface water will inhibit the reproduction and chemotaxis of C. elegans. Using our ring assay model, nematodes were enticed to cross the impaired water samples to reach a bacterial food source which allowed observation of chemotaxis. The total number of nematodes found in the bacterial food source and the middle of the plate with the impaired water source was recorded for three days. Results Our findings suggest a reduction in chemotaxis and reproduction on day three in nematodes exposed to Third Fork Creek water samples when compared to the control (pvalue<0.05). These exploratory data provide meaningful insight to the quality of Third Fork Creek located near a Historically Black University. Conclusions Further studies are necessary to elucidate the concentrations of the water contaminants and implications for human health. The relevance of this study lies within the model C. elegans, that has been used in a plethora of human diseases and exposure research but can be utilized as an environmental indicator of water quality impairment.

Rational design of hyperstable antibacterial peptides for food preservation

We describe the design of peptides with properties like thermostability, pH stability, and antibacterial activity against a few bacterial food pathogens. Insights obtained from classical structure-function analysis of natural peptides and their mutants through antimicrobial and enzymatic assays are used to rationally develop a set of peptides. pH and thermostability assays were performed to demonstrate robust antimicrobial activity post-treatment with high temperatures and at wide pH ranges. We have also investigated the mode of action of these hyperstable peptides using membrane permeability assays, electron microscopy, and molecular dynamics simulations. Notably, through mutational studies, we show that these peptides elicit their antibacterial action via both membrane destabilization and inhibition of intracellular trypsin—the two functions attributable to separate peptide segments. Finally, toxicity studies and food preservation assays demonstrate the safety and efficacy of the designed peptides for food preservation. Overall, the study provides a general ‘blueprint’ for the development of stable antimicrobial peptides (AMPs). Insights obtained from this work may also be combined with combinatorial methods in high-throughput studies for future development of antimicrobials for various applications.

Green Biosynthesized Selenium Nanoparticles by Cinnamon Extract and Their Antimicrobial Activity and Application as Edible Coatings with Nano-Chitosan

Bioactive nanocomposites were constructed, containing chitosan (Cht), extracted from shrimps’ wastes, and transformed into nanoparticles (NPs) using ionic-gelation. Selenium NPs (Se-NPs) were phytosynthesized using cinnamon (Cinnamomum zeylanicum) bark extract (CIE), characterized and evaluated with Cht-NPs as antimicrobial composites against bacterial food-borne pathogens “Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes” and as potential edible coating (EC) basements. The CIE-phytosynthesized Se-NPs had well-distributed and spherical shapes with 23.2 nm mean diameter. The CIE, CIE/Se-NPs, and innovative CIE/Se/Cht-NP composites exhibited distinguished antibacterial actions toward the entire screened pathogens; CIE/Se/Cht-NP composite was significantly the most potent. The formulated ECs from CIE/Se/Cht-NP nanocomposites had matching antibacterial manner, which was strengthened with CIE/Se-NP percentage increments. Scanning micrographs indicated the attachment of CIE/Se-NPs to bacterial cells to cause their complete lysis and death after 10 h of exposure. CIE/Se/Cht-NP composites are proposed as effectual control agents toward food-borne pathogens using efficient biological carriers and eco-friendly phytosynthesis protocol.

Distinct foraging strategies generated by single-action behavioural flexibility

Animals respond to a changing environment by adjusting their behaviour. This behavioural flexibility often involves choosing between multiple potential actions. However, little is known about how a single action can be used to achieve strategically distinct functions. Here we show that the omnivorous nematode, Pristionchus pacificus, optimizes its mixed-resource diet by prioritizing either predatory or territorial outcomes of biting the bacterivorous nematode, Caenorhabditis elegans. To determine biting incentive, P. pacificus assesses success probabilities and net energetic gains of treating C. elegans as prey, and alternatively as a competitor for bacterial food. Considering both predatory and territorial biting outcomes enables P. pacificus to pivot to territorial aggression when predation is difficult. In addition to using these outcomes to valuate biting incentive, P. pacificus designates the more lucrative outcome as its objective for biting. This biting subgoal then recruits a search subgoal that specifically promotes predatory or territorial biting, thereby unifying behaviour towards a singular foraging strategy. Furthermore, we identified the invertebrate norepinephrine analogue, octopamine, as critical for switching between predatory and territorial strategies. Collectively, our results demonstrate that behavioural flexibility on the single-action level is achieved by a hierarchy of goals and subgoals that valuate and choose from various outcome choices.

Results of Hygiene Education of Kitchen Cutting Board by using ATP Inspection - Comparison of Vegetable Cutting Board and Meat Cutting Board

Since bacteria grow in high temperature and high humidity, bacterial food poisoning frequently occurs from the rainy season to summer. In Japan, the number of food poisoning cases is high from June to October. Maintaining a hygienic environment in the kitchen is very important for preventing food poisoning. In particular, cutting boards on which various foods are places may cause secondary pollution. Therefore, to avoid food poisoning, this study compared the ATP value of the cutting board before and after the hygiene education using the ATP wiping test and investigated the educational effect. Before hygiene education, the inspector conducted an ATP wiping test on the cutting boards for vegetables and meat that washed before and after cooking and notified the cooks of the values. The inspector conducted hygiene education while showing the cook how to clean the cutting board. The cutting board washed with detergent and sponge, rinsed with running water for 30 seconds or more, then this process was repeated twice.

Results of Hygiene Education of Kitchen Knife by using ATP Inspection - Comparison of Handle and Blade

In Japan, the number of food poisoning cases and the number of patients have been gradually decreasing in the last ten years. However, from the Japanese Ministry of Health, Labor and Welfare, the number of bacterial food poisoning cases has been approximately 41% of the total number in the past five years, which is still high. Therefore, in this study, to prevent food poisoning, we conducted hygiene education using the ATP test and confirmed the educational effect by comparing before and after education. ATP luminescence kit (Lumitester PD-10, LuciPac Pen) manufactured by Kikkoman Corporation used for the microbiological test. Before the hygiene education, the ATP of the knife handle, and the ATP of the knife blade measured before and after cooking. Twelve knives for vegetables and 12 knives for meat targeted. Before the hygiene education, the handle and the blade of the meat knife measured of ATP, that before cooking and washed after cooking. Further, the handle and blade of the kitchen knife for vegetables were also measured for ATP in the same manner as the knife for meat.