Spermatozoa undergo a poorly understood activation process induced by bicarbonate and mediated by cyclic adenosine 3',5'-monophosphate (cAMP). It has been assumed that bicarbonate mediates its effects through changes in intracellular pH or membrane potential; however, we demonstrate here that bicarbonate directly stimulates mammalian soluble adenylyl cyclase (sAC) activity in vivo and in vitro in a pH-independent manner. sAC is most similar to adenylyl cyclases from cyanobacteria, and bicarbonate regulation of cyclase activity is conserved in these early forms of life. sAC is also expressed in other bicarbonate-responsive tissues, which suggests that bicarbonate regulation of cAMP signaling plays a fundamental role in many biological systems.

Soluble Adenylyl Cyclase as an Evolutionarily Conserved Bicarbonate Sensor

The genetic improvement of agriculturally important species and disease control are of fundamental importance to the success of a sustainable agri-food industry. In this sense, artificial insemination (AI) is arguably the most important tool contributing to the advancement of modern animal production. Through AI, 1 ejaculate from a genetically superior male can be used to impregnate multiple females to maximize the distribution of agriculturally favorable genes. As well, AI eliminates physical contact between animals, thus limiting the spread of sexually transmitted diseases. Successful semen cryopreservation enhances these advantages of AI over natural breeding. Long-term storage facilitates semen transport over distances, permits the quarantine of semen, and enables extended use of superior germplasm, even after the sire’s death. For agriculturally important animals, semen cryopreservation is an established industry worldwide, particularly for dairy cattle. Genome resource banking to preserve the biodiversity of endangered species or valuable transgenic lines also would benefit from sperm cryopreservation. For many mammals; however, effective semen cryopreservation is not a reality because a large number of sperm are apparently infertile following freezing and thawing. Compared to fresh, 8 times more cryopreserved bovine sperm were required to achieve equivalent fertilization rates in vivo (Shannon and Vishwanath, 1995). Although AI in pigs with fresh, cooled semen is increasingly popular, the fertility of cryopreserved semen remains about half that of fresh semen (Crabo, 1991). Following either transuterine or oviductal insemination of superovulated ewes, conception rates and percentage of fer-

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.2000.tb03268.x

Semen cryopreservation in domestic animals: a damaging and capacitating phenomenon.

http://xrm.phys.northwestern.edu/research/pdf_papers/2000/flesch_bba2000.pdf

Dynamics of the mammalian sperm plasma membrane in the process of fertilization.

Current status of sperm cryopreservation: why isn't it better?

Biotechnological applications of cyclodextrins

Cholesterol Efflux-mediated Signal Transduction in Mammalian Sperm β-CYCLODEXTRINS INITIATE TRANSMEMBRANE SIGNALING LEADING TO AN INCREASE IN PROTEIN TYROSINE PHOSPHORYLATION AND CAPACITATION

Cholesterol efflux-mediated signal transduction in mammalian sperm: cholesterol release signals an increase in protein tyrosine phosphorylation during mouse sperm capacitation.

Testicular sperm that have undergone spermatogeneis and spermiogenesis appear mature from a morphological standpoint but have acquired neither progressive motility nor the ability to fertilize a metaphase Il-arrested egg. In many species, progressive motility and fertilization competence are acquired during epididyma! transit, but complete fertilization capacity in vivo is only gained upon residence in the female reproductive tract for a finite period of time. The molecular and physiological events that confer on the sperm the ability to feftilize during residence in the female tract are collectively known as pacitation.” These maturational events can also be accomplished in vitro in defined media, the composition of which approximates the environment of the female reproductive tract. Although capacitation was discovered independently by Austin (1951, 1952) and Chang (1951, 1955) nearly one-half century ago, little is known to date about the molecular basis of this important event. This brief review will consider some of the recent findings made toward an understanding of capacitation using in vitro models. The purpose of this review is not to provide an exhaustive analysis of capacitation but is to offer an

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.1998.tb01994.x

XiaoPing Ning

Papers

Cholesterol Efflux-mediated Signal Transduction in Mammalian Sperm β-CYCLODEXTRINS INITIATE TRANSMEMBRANE SIGNALING LEADING TO AN INCREASE IN PROTEIN TYROSINE PHOSPHORYLATION AND CAPACITATION

Cholesterol efflux-mediated signal transduction in mammalian sperm: cholesterol release signals an increase in protein tyrosine phosphorylation during mouse sperm capacitation.

The molecular basis of sperm capacitation.