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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOPHOTONICS - THE APPLICATION OF NOVEL IMAGING METHODOLOGIES TO LIVESTOCK PRODUCTION RESEARCH

Location: Warmwater Aquaculture Research Unit

Title: Application of quantum dot nanoparticles for potential non-invasive bio-imaging of mammalian spermatozoa

Authors
item Feugang, J -
item Youngblood, R -
item Greene, J -
item Fahad, A -
item Monroe, W -
item Willard, S -
item Ryan, P -

Submitted to: Reproductive Biology and Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2012
Publication Date: December 14, 2013
Citation: Feugang, J.M., Youngblood, R.C., Greene, J.M., Fahad, A.S., Monroe, W.A., Willard, S.T., Ryan, P.L. 2013. Application of quantum dot nanoparticles for potential non-invasive bio-imaging of mammalian spermatozoa. Reproductive Biology and Endocrinology. 10:45-53.

Interpretive Summary: Various obstacles are encountered by mammalian spermatozoa during their journey through the female genital tract, and only few or none will reach the site of fertilization. Currently, there are limited technical approaches for non-invasive investigation of spermatozoa migration after insemination. As the knowledge surrounding sperm behavior throughout the female genital tract still remains elusive, the recent development of self-illuminating quantum dot nanoparticles may present a potential means for real-time in vitro and in vivo monitoring of spermatozoa. Here, we show the ability of boar spermatozoa to harmlessly interact and incorporate bioluminescent quantum dot nanoparticles. Our results demonstrate that pig spermatozoa can incorporate nanoparticles without affecting their motility and capacity to interact with the oocyte when used at an appropriated balance. We anticipate that our study will enable in-depth exploration of the male components of in vivo migration, fertilization, and embryonic development at the molecular level using this novel approach. This research has applications for gene delivery and for tracking spermatozoa in the reproductive tract which may have relevance to enhancing fertilization in livestock.

Technical Abstract: Various obstacles are encountered by mammalian spermatozoa during their journey through the female genital tract, and only few or none will reach the site of fertilization. Currently, there are limited technical approaches for non-invasive investigation of spermatozoa migration after insemination. As the knowledge surrounding sperm behavior throughout the female genital tract still remains elusive, the recent development of self-illuminating quantum dot nanoparticles may present a potential means for real-time in vitro and in vivo monitoring of spermatozoa. Here, we show the ability of boar spermatozoa to harmlessly interact and incorporate bioluminescent resonance energy transfer-conjugated quantum dot (BRET-QD) nanoparticles. The confocal microscope revealed in situ fluorescence of BRET-QD in the entire spermatozoon, while the ultra-structural analysis using the transmission electron microscope indicated BRET-QD localization on the sperm plasma membrane and intracellular compartment. In controlled-in vitro assays, bioluminescent imaging demonstrated that spermatozoa incubated with BRET-QD and luciferase substrate (coelenterazine) emit light (photons/sec) above the background, which confirmed the in situ fluorescence imaging. Most importantly, sperm motility, viability, and fertilizing potential were not affected by the BRET-QD incorporation when used at an appropriated ratio. Our results demonstrate that pig spermatozoa can incorporate BRET-QD nanoparticles without affecting their motility and capacity to interact with the oocyte when used at an appropriated balance. We anticipate that our study will enable in-depth exploration of the male components of in vivo migration, fertilization, and embryonic development at the molecular level using this novel approach.

Last Modified: 9/10/2014
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