STUDY QUESTION What is the behavioral mechanism underlying the response of human spermatozoa to a temperature gradient in thermotaxis? SUMMARY ANSWER Human spermatozoa swim up a temperature gradient by modulating their speed and frequencies of hyperactivation events and turns. WHAT IS KNOWN ALREADY Capacitated human spermatozoa are capable of thermotactically responding to a temperature gra...

Background: Spermatozoa are able to sense an attractant molecule gradient and as a consequence, orient their movement towards the source of the attractant. This mechanism is known as sperm chemotaxis. In recent years, our laboratory contributed to the knowledge of several features of mammalian sperm chemotaxis. These include the size and physiological state of the chemotactic sperm population, ...

There is a fundamental body of evidence suggesting that activated apoptosis signaling in ejaculated human sperm negatively influences their fertilization potential. However, it is still controversial whether this apoptotic signaling is a relic of an abortive apoptosis related to spermatogenesis or if it should be regarded as a functional preformed pathway in mature sperm leading to stereotypica...

This chapter will discuss the various sperm preparation and selection techniques used to process sperm for use with assisted reproductive techniques: swim-down, swim-up, migrationsedimentation, density gradient centrifugation, magnetic activated cell sorting, and glass wool filtration. It will also explain the procedures used to prepare viscous semen samples as well as when to obtain and prepar...

The Caenorhabditis elegans anteroposterior axis is established in response to fertilization by sperm. Here we present evidence that RhoA, the guanine nucleotide-exchange factor ECT-2, and the Rho guanosine triphosphatase-activating protein CYK-4 modulate myosin light-chain activity to create a gradient of actomyosin, which establishes the anterior domain. CYK-4 is enriched within sperm, and pat...

Sperm cells were isolated from corn (Zea mays L.) tricellular pollen grains. They were released using a light osmotic chock, and separated from pollen contaminants (especially starch grains) by a Percoll gradient centrifugation. Isolated sperm cells (3 x 10(6) per milliliter) show a high viability score (90%) as demonstrated with the fluorochromatic reaction. They appeared as spherical cells wh...

BACKGROUND There are no studies relating the apoptotic marker caspase-3 in human sperm to different degrees of abnormal sperm concentration, morphology and rapid progressive motility. METHODS Semen from 67 males with abnormal semen analyses (n = 61) and normozoospermia (n = 6) were used. In each case, sperm from the neat semen (semen fraction) and after gradient centrifugation and swim-up (sw...

When females mate promiscuously, female sperm storage provides scope to bias the fertilization success towards particular males via the non-random acceptance and utilization of sperm. The difficulties observing post-copulatory processes within the female reproductive tract mean that the mechanisms underlying cryptic female choice remain poorly understood. Here, we use zebra finches Taeniopygia ...

Sperm competition affects sexual selection intensity on males, but models suggest it cannot affect the relative intensity of sexual selection on males compared to females. However, if sperm competition depresses the payoff for male multiple mating, it could affect the relative intensity of sexual selection and even cause sexual selection to be more intense on females than males (reversal of typ...