Point-of-care impedimetric aptasensor to detect the luteinizing hormone.

Luteinizing hormone (LH) is a useful biomarker for identifying ovulation events in the cows to predict the time of ovulation to achieve a high success rate of conception following artificial insemination. Although antibody-based radioimmunoassay and enzyme-linked immunosorbent assay are being used for LH measurement, these techniques are expensive, time-consuming, and require expertise and sophisticated laboratory facilities. So, there is a need for a field-applicable, affordable, easy-to-use method for LH detection. For developing such a specific, quantitative, and inexpensive system, an aptamer-based smartphone-enabled aptasensor has been investigated. The aptamer was used instead of the antibody as a biorecognition element due to its comparative stability at ambient temperature, ease of synthesis, and cost-effectiveness. Electrochemical impedance spectroscopy has been used to obtain label-free detection of LH within 20 min in ~ 20 µL sample volume. The screen-printed gold electrode is compatible with a smartphone-enabled miniaturized device (Sensit Smart; Palmsens BV, The Netherlands) and was fabricated with the aptamer to detect LH in biological fluids (limit of detection 0.80 and 0.61 ng/mL in buffer and undiluted/unprocessed serum, respectively, with the dynamic range of detection of 0.01 to 50 ng/mL). All the data were obtained in the 10 kHz to 0.10 Hz frequency range at a bias potential of 0.30 V with an alternating potential of 10 mV. The clinical relevance of the sensor was evaluated in 10 serum samples collected from dairy animals which established a high correlation with standard LH-ELISA (κ > 0.87). The aptasensor can be stored at room temperature for 30 days without any significant loss in electrochemical sensing ability.

Identification of potential pheromone source in sows.

Pheromones play a pivotal role in intra-species communication for reproduction and social behavior in a variety of mammals, such as boars. For boars, saliva is a rich source of pheromones, however, the identification of additional sources and relative abundance of pheromones in various body fluids of sows is also essential to understand the reproductive behaviors of pigs. The present study was designed to identify the source(s) of pheromones in sows. We collected urine, feces, saliva and cervical mucus/vaginal wash samples from sows at pre-estrus, estrus and post-estrus phases, and from gilts and exposed boars to each of these potential sources of pheromones. All the boars tested spent more time sniffing and hyper-salivating in response to urine from sows in estrus than that from sows not in estrus. The sniffing behavior of boars towards estrus samples differed from that towards the samples from non-estrus sows (P < 0.005) and gilts (P < 0.001). Further, hypersalivation behavior of boars differed between estrus samples and gilt samples (P < 0.05) and estrus samples compared to pre-estrus samples (P < 0.05). This is an indication that pheromones are abundant in the estrus samples. We conclude that urine of estrus sows can be a rich source of pheromones and the same can be used to identify, purify and characterize novel pheromone molecules.