Tee, L. F. | bioRxiv Science

bioRxiv2021

Electric shock causes fear-like persistent behavioral response in the nematode Caenorhabditis elegans

Behavioral persistency reflects internal brain states, which are the foundations of multiple brain functions. However, experimental paradigms that enable genetic analyses of behavioral persistency and its associated brain functions have been limited. Here we report novel persistent behavioral responses caused by electric stimuli in the nematode Caenorhabditis elegans. When the animals on bacterial food are stimulated by alternating current, their movement speed suddenly increases more than 2-fold, which persists for minutes even after the electric stimulation is terminated. Genetic analyses reveal that multiple types of voltage-gated channels are required for the response, possibly as the sensors, and neuropeptide signaling regulates the duration of the persistent response. Additional behavioral analyses indicate that the animals response to electric shock is scalable and has a negative valence. These properties, along with persistence, have been recently regarded as essential features of emotion, suggesting that the animals response to electric shock may express a form of emotion, such as fear.

neuroscience↗

bioRxiv2017

Rapid Detection of Sepsis using CESDA: the Caenorabditis elegans Sepsis Detection Assay

Sepsis is a life-threatening condition which could be alleviated by rapid diagnosis and appropriate antibiotic administration. However, currently available laboratory tests for sepsis diagnosis lacks sensitivity and specificity; they also have long turn-around times. In this proof-of-concept study, the nematode Caenorhabditis elegans was used as a biological sensor to detect urine of sepsis patients in an assay designated as the C. elegans Sepsis Detection Assay (CESDA). From January to June 2016, 45 patients who were admitted to the Emergency Department of a university hospital due to suspected sepsis were included into the study. Urine samples were obtained from these patients and healthy controls and spotted onto CESDA assay plates. Subsequently, C. elegans were aliquoted onto the centre of the plates and allowed to migrate freely. Number of worms found in either spots or quadrants of the plates containing control or suspected sepsis samples were scored in 10 minute intervals in a 60-minute duration. The CESDA index was then calculated for each sample, where an index near +1 represented attraction of the worms towards the sample, while an index near -1 signified repulsion. Confirmatory diagnosis for suspected sepsis samples was determined using a combination of clinical criteria assessment and standard laboratory protocols. All patients who were positive for sepsis were found to have a CESDA index of > 0.1 (positive predictive value, PPV [≥]87%). In addition, the worms were able to differentiate urine of sepsis patients from control as early as 20 minutes (p=0.012). Interestingly, the assay was also able to identify infection within 40 minutes of the test (AUROC = 0.80, p= 0.016). The rapidity of CESDA in sepsis and infection identification as well as the usability of urine samples which are non-invasive towards the patient in this method makes it an interesting protocol to be further explored for sepsis diagnosis.

microbiology↗