Gallardo Bolanos J.M.,Avd Of La University S N |
Balao Da Silva C.M.,Avd Of La University S N |
Martin Munoz P.,Avd Of La University S N |
Morillo Rodriguez A.,Avd Of La University S N |
And 6 more authors.
Reproduction | Year: 2014
AKT, also referred to as protein kinase B (PKB or RAC), plays a critical role in controlling cell survival and apoptosis. To gain insights into the mechanisms regulating sperm survival after ejaculation, the role of AKT was investigated in stallion spermatozoa using a specific inhibitor and a phosphoflow approach. Stallion spermatozoa were washed and incubated in Biggers-Whitten-Whittingham medium, supplemented with 1% polyvinyl alcohol (PVA) in the presence of 0 (vehicle), 10, 20 or 30 μM SH5, an AKT inhibitor. SH5 treatment reduced the percentage of sperm displaying AKT phosphorylation, with inhibition reaching a maximum after 1 h of incubation. This decrease in phosphorylation was attributable to either dephosphorylation or suppression of the active phosphorylation pathway. Stallion spermatozoa spontaneously dephosphorylated during in vitro incubation, resulting in a lack of a difference in AKT phosphorylation between the SH5-treated sperm and the control after 4 h of incubation. AKT inhibition decreased the proportion of motile spermatozoa (total and progressive) and the sperm velocity. Similarly, AKT inhibition reduced membrane integrity, leading to increased membrane permeability and reduced the mitochondrial membrane potential concomitantly with activation of caspases 3 and 7. However, the percentage of spermatozoa exhibiting oxidative stress, the production of mitochondrial superoxide radicals, DNA oxidation and DNA fragmentation were not affected by AKT inhibition. It is concluded that AKT maintains the membrane integrity of ejaculated stallion spermatozoa, presumably by inhibiting caspases 3 and 7, which prevents the progression of spermatozoa to an incomplete form of apoptosis.
Kilders E.S.,Avd Of La University S N |
Meller R.,MPS |
Jimenez A.L.,IAA CSIC |
Hirzberger J.,MPS |
And 10 more authors.
Proceedings of 2016 ESA Workshop on Aerospace EMC, Aerospace EMC 2016 | Year: 2016
EMC requirements for scientific satellites are usually very stringent and much more demanding than terrestrial standards, mainly because ad-hoc scientific instruments developed for the mission require very quiet electromagnetic environments to perform their science. These requirements will assure the compatibility of all instruments on board and with the platform. The electromagnetic noise generated by the DC/DC converter of the PHI instrument, to be flown on board Solar Orbiter, has been drastically reduced applying several different techniques. One technique has been to change the grounding strategy from a single point grounding to a distributed grounding. Two additional techniques were needed to reach the required noise floor. Experimental measurements show the improvements achieved with each technique. © 2016 ESA.