Marked sperm dimorphism in the ground beetleScarites terricola: a novel type of insect sperm polymorphism

Although there have been numerous studies concerning the morphogenetic changes accompanying the maturation of insect sperm, only a few deal with the sperm differentiation in the dragonflies. In two recent electron microscopic studies Kessel, has comprehensively treated the erlationship of microtubules to the nucleus and mid-piece structures during spermiogenesis in the dragonfly. The purpose of this study is to follow the sequential nuclear and cytoplasmic changes which accompany the differentiation of spermatogonium into a mature sperm during spermatogenesis in the dragonfly (Aeschna sp.).The dragonfly spermatogonia are characterized by large round nuclei. Loosely organized chromatin is usually unevenly distributed within the spermatogonial nuclei. The scant cytoplasm surrounding the nucleus contains mitochondria, the Golgi apparatus, elements of endoplasmic reticulum and numerous ribosomes (Fig. 1).

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Protein of insect sperm mitochondrial crystals. Crystallomitin.

The Journal of Cell Biology ◽

10.1083/jcb.73.3.594 ◽

1977 ◽

Vol 73 (3) ◽

pp. 594-600 ◽

Cited By ~ 36

Author(s):

B Baccetti ◽

R Dallai ◽

V Pallini ◽

F Rosati ◽

B A Afzelius

Keyword(s):

Sodium Dodecyl Sulfate ◽

Sodium Dodecyl ◽

Dodecyl Sulfate ◽

Filament Bundles ◽

Cross Links ◽

Insect Sperm ◽

Main Period ◽

20 Nm ◽

Derivatives Of

Mitochondrial derivatives of insect sperm usually contain a crystalline protein that shows a 45-nm main period, made up of 20-nm subperiods, determined by the coiling of filament bundles. Filaments are 2 nm thick and have a globular appearance. The crystals contain two main polypeptides, 52,000 and 55,000 daltons. These polypeptides are closely related, contain a high percentage of proline, and are insoluble in sodium dodecyl sulfate due to disulfide cross links. We suggest for this class of protein the name crystallomitin.

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Ultrastructural evidence of sperm dimorphism in Deladenus sp. (Tylenchomorpha: Sphaerularioidea: Allantonematidae)

Nematology ◽

10.1163/156854107781352043 ◽

2007 ◽

Vol 9 (3) ◽

pp. 397-404 ◽

Cited By ~ 5

Author(s):

Hajime Kosaka ◽

Manabu Kusunoki ◽

Vladimir Yushin

Keyword(s):

Electron Microscope ◽

Parasitic Nematode ◽

Spermatogenic Cells ◽

Ultrastructural Evidence ◽

Transmission Electron ◽

Parallel Fibres ◽

Sperm Dimorphism ◽

Whole Life Cycle ◽

First Time ◽

Spherical Vesicles

AbstractThe dimorphic spermatozoa of the insect-parasitic nematode Deladenus sp. (Tylenchomorpha: Sphaerularioidea: Allantonematidae) were studied for the first time with a transmission electron microscope (TEM). The immature spermatozoa from the testis of mycetophagous males are 10-12 μm diam. and 4-5 μm long unpolarised cells with a centrally located nucleus without a nuclear envelope. The cytoplasm contains mitochondria and specific components, membranous organelles (MO) and fibrous bodies (FB). The MO are spherical vesicles with an internal system of finger-like invaginations of the membrane; the spindle-shaped FB consist of tightly packed parallel fibres. Spermatozoa from the uteri of infective females of Deladenus sp. are vastly different in size being tiny cells ca 2 μm diam. with a spherical or oval nucleus. Each cell contains several mitochondria and MO. Although each individual of Deladenus sp. contains only monomorphic spermatozoa, sperm dimorphism was revealed after analysis of the whole life cycle. Despite a difference in size the cytological characters of both types of spermatozoa conform to the typical rhabditid pattern. The presence of both MO and FB in sphaerularioidid spermatozoa differentiates the superfamily Sphaerularioidea from Tylenchoidea whose representatives lack MO in the spermatogenic cells.

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