Molecular structure of dynein and motility of a giant sperm axoneme provided with only the outer dynein arm

Abstract

The peculiar sperm axoneme of the dipteran Asphondylia ruebsaameni is characterized by an extraordinarily high number of microtubule doublets (up to 2,500) arranged in double parallel spirals. Doublets of the inner row of each spiral are tilted, so that their outer arms point towards the B-tubule of the next doublet in the outer row. Doublets are provided with only the outer arm, and no structure related to the central pair/radial spoke complex is present. When analyzed by quick-freeze, deep-etch electron microscopy, the structure of the dynein arms was shown to share the same organization described in other organisms; however, it appears to be somewhat more complex than that previously found in a related dipteran species, Monarthropalpus flavus, since the foot region of the arms displays a globular extra-domain that is intercalated between adjacent arms. Treatment of demembranated sperm with ATP and vanadate induced conformational changes in the dynein arms. SDS-page suggested the presence of a single dynein high molecular weight band or, in the gels with the best electrophoretic resolution, of two very closely spaced bands. This polypeptide positively reacted with a polyclonal antibody raised against a specific amino acid sequence located in the phosphate-binding loop of the dynein catalytic site. Dynein heavy chain-related DNA sequences corresponding to the catalytic phosphate-binding region were amplified by RT-PCR. Two distinct fragments (Asph-ax1 and Asph-ax2) encoding axonemal dynein sequences were identified. Southern blot analysis performed on genomic DNA using these sequences as a probe showed that they are part of different genes. An intron was identified in the Asph-ax1 fragment at a position corresponding to the site of a nucleotide deletion in the putative pseudogene of Monarthropalpus. Asphondylia spermatozoa exhibited in vivo a whirling movement both in the deferent duct and in the spermatheca, but they were unable to undergo processive movement in vitro. They propagated a three-dimensional wave only when constrained in a bent configuration by some mechanical means. The phylogenetic relationships between the two dipteran species, Monarthopalpus and Asphondylia, based on these biochemical and molecular data are also discussed.

Insect Sperm Motility

“…Despite missing the inner dynein arms, these spermatozoa are motile. Case studies of the Cecidomyiinaeans Monarthropalpus flavus (Schrank) (Lupetti et al , 1998) and Asphondylia ruebsaameni Kertesz (Mencarelli et al , 2001) revealed that spermatozoa stored within the male genital tract are folded into several turns. Folded spermatozoa are exhibiting a continuous train of bends running along the flagellum.…”

“…In normal flagella, the ability to generate regular flagellar bending resides with the central complex and the inner dynein arms which are crucial in the regulation and coordination of dynein function (Gardner et al , 1994). In the case of Monarthropalpus flavus and Asphondylia ruebsaameni spermatozoa it was suggested that dynein function is regulated by external mechanical stimuli which compensate for the lack of inner dynein arms (Lupetti et al 1998, Mencarelli et al , 2001). This is also true for insect spermatozoa with the conventional axoneme structure (see Section V.).…”

Exploitation of sperm‐Escherichia coli interaction at the receptor‐ligand level for the development of anti‐receptor antibodies as the vaginal contraceptive

“…This hydrolysis is being carried out by dyenin ATPase which is an Mg 2+ ‐dependent enzyme localized on the axoneme (Gibbons & Gibbons, ). The importance of these dyenin arms in motility has clearly been established in several experiments showing a direct correlation between the quantity of dyenin arms present on the axoneme and the sliding velocity (Mencarelli et al ., ). In this study, Mg 2+ ‐dependent ATPase activity decreased from 1580 ± 2.0 units in control to 1020 ± 0.53 ( p < 0.01) units upon incubation with anti‐SR antibodies.…”

The tailored sperm cell

“…2). From the 3 + 0 structure in the parasitic protozoan Diplauxis hatti to the giant axoneme of the dipteran Asphondylia ruebsaameni with 2,500 microtubule doublets (Mencarelli et al 2001), variations are rich.…”