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Behavioral mechanisms of mammalian sperm guidance.

Perez-Cerezales S, Boryshpolets S, Eisenbach M - Asian J. Androl. (2015 Jul-Aug)

Bottom Line: In mammals, sperm guidance in the oviduct appears essential for successful sperm arrival at the oocyte.Hitherto, three different potential sperm guidance mechanisms have been recognized: thermotaxis, rheotaxis, and chemotaxis, each of them using specific stimuli - a temperature gradient, fluid flow, and a chemoattractant gradient, respectively.Here, we review sperm behavioral in these mechanisms and indicate commonalities and differences between them.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel.

ABSTRACT
In mammals, sperm guidance in the oviduct appears essential for successful sperm arrival at the oocyte. Hitherto, three different potential sperm guidance mechanisms have been recognized: thermotaxis, rheotaxis, and chemotaxis, each of them using specific stimuli - a temperature gradient, fluid flow, and a chemoattractant gradient, respectively. Here, we review sperm behavioral in these mechanisms and indicate commonalities and differences between them.

No MeSH data available.


Mammalian sperm chemotaxis. (a) Tracks showing different types of responses to photorelease of the chemoattractant progesterone from its caged compound. The arrows indicate the direction of swimming. The purple dot indicates the time of the flash. (b) A model for the behavior of human spermatozoa in a spatial chemoattractant gradient. The intensity of the background color represents the chemoattractant concentration (Taken with permission from Armon and Eisenbach26).
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Figure 1: Mammalian sperm chemotaxis. (a) Tracks showing different types of responses to photorelease of the chemoattractant progesterone from its caged compound. The arrows indicate the direction of swimming. The purple dot indicates the time of the flash. (b) A model for the behavior of human spermatozoa in a spatial chemoattractant gradient. The intensity of the background color represents the chemoattractant concentration (Taken with permission from Armon and Eisenbach26).

Mentions: The notion of hyperactivation events and turns being major factors in directing spermatozoa in a chemoattractant gradient was clearly demonstrated both in spatial and temporal gradients. Specifically, the fraction of human spermatozoa identified as hyperactivated (equivalent to the frequency of hyperactivation events) was found smaller when the cells were in a spatial gradient of the chemoattractant progesterone, suggesting that capacitated spermatozoa maintain their course of swimming once they find the right direction (up the gradient) and turn less frequently.26 The sperm response to a temporal chemoattractant gradient is more complex, but well consistent with the observed behavior in a spatial gradient. Specifically, photorelease of the chemoattractant progesterone from its caged compound, evenly distributed in the sperm suspension, resulted in turnings and hyperactivation events, always following a short delay period (Figure 1a).26 A similar behavior was observed when cAMP or cGMP was photoreleased from their caged compounds within spermatozoa, suggesting the involvement of these cyclic nucleotides in the chemotactic response.27 This means that the attractant response consists of two phases: a delay and a turn. On the basis of these results Armon and Eisenbach26 proposed a model for sperm behavior in a spatial chemoattractant gradient (Figure 1b). According to this model, when a capacitated spermatozoon swims up the chemoattractant concentration it is continuously stimulated. This means that before the second phase commences the cell is stimulated again and again. The outcome is that only the first phase of the response occurs, meaning swimming straight ahead without turns and hyperactivation events. This situation prevails until the spermatozoon stops sensing the gradient, in which case it would adapt and restore the unstimulated mode of swimming, consisting of rather linear swimming interrupted by occasional episodes of hyperactivation, or until it happens to swim down the gradient. In that case it would exhibit turns and hyperactivation episodes to modify its direction of swimming. If so, the behavioral response of human spermatozoa to a spatial chemoattractant gradient (but not to a temporal gradient) is very similar to that of E. coli. In both cases, an increasing concentration gradient of a chemoattractant would suppress turning events, whereas a decrease would increase the frequency of such events.


Behavioral mechanisms of mammalian sperm guidance.

Perez-Cerezales S, Boryshpolets S, Eisenbach M - Asian J. Androl. (2015 Jul-Aug)

Mammalian sperm chemotaxis. (a) Tracks showing different types of responses to photorelease of the chemoattractant progesterone from its caged compound. The arrows indicate the direction of swimming. The purple dot indicates the time of the flash. (b) A model for the behavior of human spermatozoa in a spatial chemoattractant gradient. The intensity of the background color represents the chemoattractant concentration (Taken with permission from Armon and Eisenbach26).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492055&req=5

Figure 1: Mammalian sperm chemotaxis. (a) Tracks showing different types of responses to photorelease of the chemoattractant progesterone from its caged compound. The arrows indicate the direction of swimming. The purple dot indicates the time of the flash. (b) A model for the behavior of human spermatozoa in a spatial chemoattractant gradient. The intensity of the background color represents the chemoattractant concentration (Taken with permission from Armon and Eisenbach26).
Mentions: The notion of hyperactivation events and turns being major factors in directing spermatozoa in a chemoattractant gradient was clearly demonstrated both in spatial and temporal gradients. Specifically, the fraction of human spermatozoa identified as hyperactivated (equivalent to the frequency of hyperactivation events) was found smaller when the cells were in a spatial gradient of the chemoattractant progesterone, suggesting that capacitated spermatozoa maintain their course of swimming once they find the right direction (up the gradient) and turn less frequently.26 The sperm response to a temporal chemoattractant gradient is more complex, but well consistent with the observed behavior in a spatial gradient. Specifically, photorelease of the chemoattractant progesterone from its caged compound, evenly distributed in the sperm suspension, resulted in turnings and hyperactivation events, always following a short delay period (Figure 1a).26 A similar behavior was observed when cAMP or cGMP was photoreleased from their caged compounds within spermatozoa, suggesting the involvement of these cyclic nucleotides in the chemotactic response.27 This means that the attractant response consists of two phases: a delay and a turn. On the basis of these results Armon and Eisenbach26 proposed a model for sperm behavior in a spatial chemoattractant gradient (Figure 1b). According to this model, when a capacitated spermatozoon swims up the chemoattractant concentration it is continuously stimulated. This means that before the second phase commences the cell is stimulated again and again. The outcome is that only the first phase of the response occurs, meaning swimming straight ahead without turns and hyperactivation events. This situation prevails until the spermatozoon stops sensing the gradient, in which case it would adapt and restore the unstimulated mode of swimming, consisting of rather linear swimming interrupted by occasional episodes of hyperactivation, or until it happens to swim down the gradient. In that case it would exhibit turns and hyperactivation episodes to modify its direction of swimming. If so, the behavioral response of human spermatozoa to a spatial chemoattractant gradient (but not to a temporal gradient) is very similar to that of E. coli. In both cases, an increasing concentration gradient of a chemoattractant would suppress turning events, whereas a decrease would increase the frequency of such events.

Bottom Line: In mammals, sperm guidance in the oviduct appears essential for successful sperm arrival at the oocyte.Hitherto, three different potential sperm guidance mechanisms have been recognized: thermotaxis, rheotaxis, and chemotaxis, each of them using specific stimuli - a temperature gradient, fluid flow, and a chemoattractant gradient, respectively.Here, we review sperm behavioral in these mechanisms and indicate commonalities and differences between them.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel.

ABSTRACT
In mammals, sperm guidance in the oviduct appears essential for successful sperm arrival at the oocyte. Hitherto, three different potential sperm guidance mechanisms have been recognized: thermotaxis, rheotaxis, and chemotaxis, each of them using specific stimuli - a temperature gradient, fluid flow, and a chemoattractant gradient, respectively. Here, we review sperm behavioral in these mechanisms and indicate commonalities and differences between them.

No MeSH data available.