Reproduction Abstracts

Introduction: Mammalian cell based biosensor consists of biological entity which can be whole mammalian cell, i.e. gametic or somatic cells that interacts with an analyte and produces a signal which can be measured fluorimetrically, colorimetrically, etc. Mammalian cell based biosensor not only helps in the detection but also detect physiological changes Spermatozoa based biosensor rapidly interpret the inherent interaction of spermatozoa with cereulide in a physiologically relevant manner. Use of ejaculated spermatozoa for studying the toxic effects of mitochondrial toxins provide several advantages over other in vitro systems due to their highly active and sensitive mitochondria. Cereulide, a dodecadepsipeptide produced by B. cereus which is an opportunistic pathogen belongs to hazardous group 2. Cereulide toxin is highly resistant to pH, temperature, radiations, etc. Milk powder is mainly contaminated with this toxin.

Material and methods: Different B. cereus cultures purchased from MTCC were screened for cereulide production. Certified milk powder was inoculated with viable counts of B. cereus (10³–10⁴) and cereulide was purified using HPLC using valinomycin as standard. Different concentrations of cereulide was prepared and examined by spermatozoa motility assay. EC₅₀ value was calculated which was also validated with five different milk powders.

Results and discussion: This bioassay is non-laborious and can be executed with equipments present in most of the laboratories. Cereulide has potassium ionophoric action which inhibit transmembrane potential and mitochondrial activity and easily detected through spermatozoa. EC₅₀ value calculated was 5 ng/ml, i.e. the lowest concentration of cereulide extracted from milk powder which inhibit the motility of 50% of buffalo spermatozoa.