Seminal plasma ingredients are important for maintenance of sperm viability. This study focuses on the effect of boar seminal plasma exosomes on sperm function during long-term liquid storage. Boar seminal plasma exosomes had typical nano-structure morphology as measured by scanning electron microscopy (SEM) and molecular markers such as AWN, CD9 and CD63 by western blot analysis. The effect on sperm parameters of adding different ratio of boar seminal plasma exosomes to boar sperm preparations was analyzed. Compared to the diluent without exosomes, the diluent with four times or sixteen times exosomes compared to original semen had higher sperm motility, prolonged effective survival time, improved sperm plasma membrane integrity (p < 0.05), increased total antioxidant capacity (T-AOC) activity and decreased malondialdehyde (MDA) content. The diluent containing four times concentration of exosomes compared to original semen was determined to inhibit premature capacitation, but not to influence capacitation induced in vitro. Inhibition of premature capacitation is likely related to the concentration of exosomes which had been demonstrated to transfer proteins including AWN and PSP-1 into sperm. In addition, using fluorescence microscopy and scanning electron microscopy analysis, it was demonstrated that exosomes in diluent were directly binding to the membrane of sperm head which could improve sperm plasma membrane integrity.
We
report here the synthesis of poly(4-ketovalerolactone) (PKVL)
via ring-opening transesterification polymerization (ROTEP) of the
monomer 4-ketovalerolactone (KVL, two steps from levulinic acid).
The polymerization of KVL proceeds to high equilibrium monomer conversion
(up to 96% in the melt) to give the semicrystalline polyketoester
PKVL. PKVL displays glass transition temperatures of 7 °C and
two melting temperatures at 132 and 148 °C. This polyester can
be chemically recycled through hydrolytic degradation. Under aqueous
neutral or acidic conditions, the dominating pathway for polyester
hydrolysis is through backbiting from the chain end. Under basic conditions,
midchain cleavage, accelerated by the ketone carbonyl group in the
backbone, promotes the hydrolysis of nearby backbone ester bonds.
The final hydrolysis product is 5-hydroxylevulinic acid, the
ring-opened hydrolysis product of KVL. PKVL was also observed to degrade
under the action of a Brønsted acid to a bis-spirocyclic dilactone
natural product altaicadispirolactone, which is a dimer of KVL. This
constitutes a rare example of a one-step synthesis of a secondary
metabolite of nontrivial structure in which a polymer was the starting
material and the sole source of matter. Analogous ROTEP of the isomeric
four-membered lactone 4-acetyl-β-propiolactone (APL) was also
explored, although this chemistry was not as well-behaved as the KVL
to PKVL polymerization.
Sialic acid (SA), which usually occupies the terminal position of oligosaccharide chains in mammalian spermatozoa, has important functions in fertilization. Compared with other methods, such as lectin probing, boronic acid could recognize and bind SA with a higher affinity and specificity at pH 6.9. In this study, two boronic acid carriers, 3-aminophenylboronic acid-labeled fluorescent latex (CML-APBA) and magnetic beads (CMM-APBA were applied to explore surface sialylation profile and sialoglycoproteins of the boar sperm. There are three binding sections of CML-APBA on the head of ejaculated sperm: acrosomal region, equatorial segment and the head posterior, which are the major regions undergoing sialylation. After capacitation , two major binding patterns of CML-APBA exists on sperm head. On some spermatozoa, sialylation exists on the equatorial segment and the posterior head, whilst on other spermatozoa, sialylation occurs on the acrosomal region and equatorial segment. Flow cytometry analysis suggested that the level of sialylation on boar sperm membrane decreases after capacitation. Furthermore, using CMM-APBA, we pulled down sialylated proteins from spermatozoa. Among them, two decapacitation factors associating on sperm surface, AWN and PSP-1, were identified. The levels of the two proteins reduced during capacitation, which might contribute to the decrease of sialylation on boar sperm surface.
The stereoselective construction of the CDEFGH ring system of lancifodilactone G is described. The key steps in this synthesis are (i) ring-closing metathesis for formation of the oxa-bridged eight-membered ring; (ii) an intramolecular Pauson-Khand reaction for construction of the sterically congested F ring; and (iii) sequential cross-metathesis, hydrogenation, and lactonization reactions for installation of the anomerically stabilized bis-spiro ketal fragment of lancifodilactone G.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.