Germ-cell hub position in a heteropteran testis correlates with the sequence and location of spermatogenesis and production of elaborate sperm bundles.

In insects, spermatogonial cells undergo several mitotic divisions with incomplete cytokinesis, and then proceed through meiosis and spermatogenesis in synchrony. The cells derived from a single spermatogonial cell are referred to as a cyst. In the water strider Aquarius remigis, spermiogenesis occurs within two bi-lobed testes.

Waveform generation is controlled by phosphorylation and swimming direction is controlled by Ca2+ in sperm from the mosquito Culex quinquefasciatus.

Most animal sperm are quiescent in the male reproductive tract and become activated after mixing with accessory secretions from the male and/or female reproductive tract. Sperm from the mosquito Culex quinquefasciatus initiate flagellar motility after mixing with male accessory gland components, and the sperm flagellum displays three distinct motility patterns over time: a low amplitude, a long wavelength form (Wave A), a double waveform consisting of two superimposed waveforms over the length of the flagellum (Wave B), and finally, a single helical waveform that propels the sperm at high velocity (Wave C). This flagellar behavior is replicated by treating quiescent sperm with trypsin.

Protease activation and the signal transduction pathway regulating motility in sperm from the water strider Aquarius remigis.

Many motile processes are regulated such that movement occurs only upon activation of a signaling cascade. Sperm from a variety of species are initially quiescent and must be activated prior to beating. The signaling events leading to the activation and regulation of sperm motility are not well characterized.

Dynein, dynactin, and kinesin II's interaction with microtubules is regulated during bidirectional organelle transport.

The microtubule motors, cytoplasmic dynein and kinesin II, drive pigmented organelles in opposite directions in Xenopus melanophores, but the mechanism by which these or other motors are regulated to control the direction of organelle transport has not been previously elucidated. We find that cytoplasmic dynein, dynactin, and kinesin II remain on pigment granules during aggregation and dispersion in melanophores, indicating that control of direction is not mediated by a cyclic association of motors with these organelles. However, the ability of dynein, dynactin, and kinesin II to bind to microtubules varies as a function of the state of aggregation or dispersion of the pigment in the cells from which these molecules are isolated.