Mitochondrial Derivatives Research Articles

Ultrastructure of male reproductive system of Eurydema ventrale Kolenati 1846 (Heteroptera: Pentatomidae).

The male reproductive system of Eurydema ventrale Kolenati 1846 is studied morphologically and histologically by using light, scanning and transmission electron microscopes. The reproductive system of the male E.ventrale consists of a pair of testis, a pair of vas deferens, a pair of seminal vesicles, accessory glands, a bulbus ejaculatorius, a pair of ectodermal sacs, and a ductus ejaculatorius. The testicular follicles have three different development zones (growth zone, maturation zone, and differentiation zone). The testes are connected to the seminal vesicles by the vas deferens that is a specialized in sperm storage. Sperm have an elongated head and a tail (flagellum) with an axonema and two mitochondrial derivatives. Vas deferens and seminal vesicles are fine, long, and cylindrical. The seminal vesicle is connected with bulbus ejaculatorius, which is balloon shaped and surrounded with accessory glands. The bulbus ejaculatorius is continuous with ductus ejaculatorius which is connected to the aedeagus.

The sperm ultrastructure and spermiogenesis of Tribolium castaneum (Coleoptera: Tenebrionidae) with evidence of cyst degeneration

Previous studies on the spermatogenesis of tenebrionid beetles showed the unusual formation of two antiparallel sperm bundles per cyst. In this work we reported this feature also in Tribolium castaneum using light and transmission electron microscopy. The sperm structure of T. castaneum, similar to other tenebrionids, consists of a three-layered acrosome, an elongated nucleus and a flagellum with a 9+9+2 axoneme, two accessory bodies and two asymmetric mitochondrial derivatives. The presence of two antiparallel sperm bundles per cyst also in Meloidae and Rhipiphoridae suggests that it is a strong trait synapomorphic for Tenebrionoidea. The huge degeneration of whole sperm cells in several cysts of testes during spermiogenesis is also described.

ULTRASTRUCTURE OF THE SPERM OF APLYSIA CALIFORNICA COOPER

The structure of the sperm of Aplysia californica was studied by both transmission and scanning electron microscopy. Aplysia californica, a species with internal fertilization, has the modified type of molluscan sperm structure. Spermatids had a glycogen helix spiraled about the flagellum, both enclosed by a common microtubular basket. A second vacuole helix was periodically seen only in spermatids and absent in spermatozoa. An additional basket of microtubules appeared to direct the elongation and spiraling of the nucleus about the flagellum/glycogen helix. A flat acrosome was present while the centriolar derivative was embedded in a deep nuclear fossa with strands of heterochromatin arranged nearly perpendicular to its long axis. The mitochondrial derivative consisted of small, frequently electron dense, closely spaced rods but individual mitochondria were also seen surrounding the axoneme of spermatids. The axoneme consisted of dense fibers that appeared to have a C shape substructure with a central dense fiber thus providing a 9+1 arrangement of singlet units; the typical 9+2 microtubule arrangement of flagella was absent. Flagella with two axonemes were frequently seen as well as an extra axoneme within the head of immature sperm.

Histological and Ultrastructural Analysis of Spermatogenesis in Gelastocoris flavus flavus (Heteroptera: Nepomorpha)

Studies on the ultrastructural aspects of spermatogenesis and, specifically, the structure of sperm in aquatic Heteroptera are scarce. Therefore, the objective of this study was to analyse of the histology and ultrastructure of spermatogenesis. Semi-fine sections of the testicles of adult male Gelastocoris flavus flavus were stained with toluidine blue or impregnated with silver ions, and ultra-fine sections were analysed by transmission electron microscopy. The ultrastructural features observed during spermatogenesis of the species showed the presence of several small mitochondria uniformly distributed in the cytoplasm of cells in prophase I. These mitochondria then came together to form fewer, larger structures, which converged and formed the mitochondrial complex. Later, this mitochondrial complex was divided into two structures, termed mitochondrial derivatives, which were arranged bilaterally to the axoneme. The axoneme showed a flagellar pattern of 9+9+2. A vesicle was observed that originated in the early stages of spermiogenesis and was composed of many argyrophilic granules that united to form a single structure. This vesicle contained some highly stained structures in its interior. Thus, this paper describes histological and ultrastructural characteristics during spermatogenesis, contributing to the reproductive knowledge of these aquatic Heteroptera

The sperm ultrastructure of Stictoleptura cordigera (Füssli, 1775) (Insecta, Coleoptera, Cerambycidae).

The spermatozoa of the longhorn beetles Stictoleptura cordigera were ultrastructurally described in this paper. They have an apical bilayered acrosome, an elongated nucleus, a centriole with star-shape links, two asymmetric mitochondrial derivatives partially crystallized and a 9+9+2 flagellar axoneme with accessory tubules provided with 16 protofilaments in their wall. A centriole adjunct is present and gives rise to two thick laminae as accessory bodies, also asymmetrical, to which two relatively small puff-like structures of different size are connected. These features were previously found in the sperm of the cerambycid Morimus asper. The strict similarity of the cerambycid sperm characters with those of curculionoids indicates a clear phylogenetic relationship between Chrysomeloidea and Curculionoidea.

The intermediate sperm type and genitalia of Zorotypus shannoni Gurney: evidence supporting infraordinal lineages in Zoraptera (Insecta)

The sperm ultrastructure and the male and female genital apparatus of Zorotypus shannoni were examined and documented in detail, mainly using transmission electron microscopy micrographs. The findings suggest an evolutionary trend shared with Z. hubbardi and Z. impolitus. The three species are characterized by enlarged mitochondrial derivatives and related modifications. Giant sperm are probably a synapomorphy of Z. hubbardi and Z. impolitus, whereas an intermediate condition of this feature is found in Z. shannoni. The monophyletic origin of Z. caudelli, Z. magnicaudelli, Z. huxleyi and Z. weidneri is suggested by characteristically modified axonemes. The presence of extra-acrosomal material is also an unusual feature for Zoraptera, but this condition also occurs in the majority of polyneopteran groups. The long and convoluted female spermathecal duct with secretory and duct-forming cells is a constant feature in Zoraptera. The enlarged seminal receptacle suggests an evolutionary link between the male genital structures and the sperm size on one hand, and the size of the female spermatheca on the other. The small and otherwise uniform group Zoraptera exhibits a remarkable variation of sperm types and genital structures, suggesting the impact of different types of selection. It is likely that cryptic female choice plays a major role in shaping the genital apparatus.

Ultrastructure of the spermatozoa of Psammotettix striatus (Linnaeus) and Exitianus nanus (Distant) (Hemiptera: Auchenorrhyncha: Cicadellidae: Deltocephalinae)

Previous studies of insect spermatozoa indicate that these specialized cells have undergone significant morphological evolution and exhibit traits useful for reconstructing phylogenetic relationships. Although leafhoppers (Cicadellidae) are among the largest and most economically important insect families, few comparative studies of their spermatozoa have been published. Here, the ultrastructure of mature spermatozoa of two leafhoppers Psammotettix striatus (Linnaeus) and Exitianus nanus (Distant), representing two different tribes of the largest leafhopper subfamily, Deltocephalinae, was examined by light and transmission electron microscopy. The shape and ultrastructure of spermatozoa of the two species are very similar to those of other Cicadellidae as well as other Auchenorrhyncha, comprising a conical acrosome invaginated to form a subacrosomal space, a filiform homogeneously condensed nucleus, a lamellate centriolar adjunct connecting the nucleus with the mid-piece/flagellum, a long flagellum with a 9 + 9 + 2 axoneme pattern and two symmetrical mitochondrial derivatives with an orderly array of peripheral cristae, and two drop-shaped accessory bodies. They may be distinguished by the size of the sperm, and the shape of the nucleus, accessory bodies, and paracrystalline region of mitochondrial derivatives. The fine morphology and ultrastructure of spermatozoon in P. striatus and E. nanus are illustrated, along with a brief discussion of the implications for classification and phylogenetic analyses of the subfamily.

Morphology of the male reproductive system, sperm ultrastructure and γ-irradiation of the red palm weevil Rhynchophorus ferrugineus Oliv. (Coleoptera: Dryophthoridae).

In the present study we describe the morphology of the male reproductive apparatus and sperm ultrastructure of the red palm weevil - an invasive pest of several palm tree species - as well as the most important steps of spermatogenesis. The reproductive apparatus consists of a pair of testes (each formed by two lobes) a long tube-like accessory gland, a prostate gland and a small accessory gland. Characteristic features of the sperm are 90-100 μm total length, 10 μm nucleus, two mitochondrial derivatives, two accessory bodies, one well-developed puff-like structure and a typical insect 9+9+2 flagellar axoneme. One of the methods used for the biological control of pests is the Sterile Insect Technique (SIT), for the evaluation of which we make a preliminary comparison of the sperm ultrastructure of non-irradiated and irradiated weevils (at a dose of 80 Gray).

Paternal Mitochondrial Destruction after Fertilization Is Mediated by a Common Endocytic and Autophagic Pathway in Drosophila

Almost all animals contain mitochondria of maternal origin only, but the exact mechanisms underlying this phenomenon are still vague. We investigated the fate of Drosophila paternal mitochondria after fertilization. We demonstrate that the sperm mitochondrial derivative (MD) is rapidly eliminated in a stereotypical process dubbed paternal mitochondrial destruction (PMD). PMD is initiated by a network of vesicles resembling multivesicular bodies and displaying common features of the endocytic and autophagic pathways. These vesicles associate with the sperm tail and mediate the disintegration of its plasma membrane. Subsequently, the MD separates from the axoneme and breaks into smaller fragments, which are then sequestered by autophagosomes for degradation in lysosomes. We further provide evidence for the involvement of the ubiquitin pathway and the autophagy receptor p62 in this process. Finally, we show that the ubiquitin ligase Parkin is not involved in PMD, implying a divergence from the autophagic pathway of damaged mitochondria.

Comparative morphology of spermatozoa and reproductive systems of zorapteran species from different world regions (Insecta, Zoraptera)

The male and female reproductive apparatus of Zorotypus magnicaudelli (Malaysia), Zorotypus huxleyi (Ecuador) and Zorotypus weidneri (Brazil) were examined and documented in detail. The genital apparatus and sperm of the three species show only minor differences. The testes are larger in Z. magnicaudelli. Z. huxleyi lacks the helical appendage in the accessory glands. A long cuticular flagellum is present in Z. magnicaudelli and in the previously studied Zorotypus caudelli like in several other species, whereas it is absent in Z. weidneri, Z. huxleyi, Zorotypus hubbardi, Zorotypus impolitus and Zorotypus guineensis. Characteristic features of the very similar sperm are the presence of: a) two dense arches above the axoneme; b) a 9 + 9+2 axoneme with detached subtubules A and B of doublets 1 and 6; c) the axonemal end degenerating with enlarging accessory tubules; d) accessory tubules with 17 protofilaments; e) three accessory bodies beneath the axoneme; and f) two mitochondrial derivatives of equal shape. The first characteristic (a) is unknown outside of Zoraptera and possibly autapomorphic. The sperm structure differs distinctly in Z. impolitus and Z. hubbardi, which produce giant sperm and possess a huge spermatheca. The presence of the same sperm type in species either provided with a sclerotized coiled flagellum in males or lacking this structure indicates that a different organization of the genital apparatus does not necessarily affect the sperm structure. The flagellum and its pouch has probably evolved within Zoraptera, but it cannot be excluded that it is a groundplan feature and was reduced several times. The fossil evidence and our findings suggest that distinct modifications in the genital apparatus occurred before the fragmentation of the Gondwanan landmass in the middle Cretaceous.

Sperm ultrastructure of Panorpodes kuandianensis (Mecoptera: Panorpodidae)

The sperm ultrastructure of the short-faced scorpionfly Panorpodes kuandianensis Zhong et al. was investigated using transmission electron microscopy. The spermatozoon is composed of a short head containing a bilayered acrosome and an elongate nucleus, a neck transition region, and a long flagellum. The acrosome consists of an acrosomal vesicle and a central perforatorium. The nucleus has two deep, U-shaped lateral grooves and its chromatin contains a series of parallel, regularly arrayed nuclear fibers. The barrel-shaped centriolar adjunct occupies the most volume of the neck region. The flagellum is helical for its whole length and is formed by an axoneme, two mitochondrial derivatives, a pair of accessory bodies, and peculiar accessory structures. The axoneme has nine accessory microtubules at the anterior flagellum region, displaying a 9 + 9 + 2 microtubular pattern, but the accessory microtubules are short and disappear quickly. The two mitochondrial derivatives differ in length and diameter. In the more posterior region, the remaining anchor-shaped mitochondrial derivative has a circular crystalline region, differing from other mecopteran species. The filiform materials are peculiar and lie beside the nucleus and in the flagellum region. Sperm ultrastructural comparison of P. kuandianensis with other families supports a close affinity of Panorpodidae with Panorpidae. In addition, the occurrence of the nine accessory microtubules in the sperm axoneme of Panorpodes indicates that the 9 + 9 + 2 axonemal pattern might be a symplesiomorphy of the Mecoptera.

Sperm Bundles in the Seminal Vesicle of the Crematogaster victima (Smith) Adult Males (Hymenoptera: Formicidae).

This study establishes the presence of spermatodesm in the seminal vesicles of sexually mature males of Crematogaster victima (Smith). In this species, the spermatozoa are maintained together by an extracellular matrix in which the acrosomal regions are embedded. This characteristic has not yet been observed in any other Aculeata. However, the sperm morphology in this species is similar to that described for other ants. The spermatozoa measure on average 100μm in length, and the number of sperm per bundle is up to 256. They are composed of a head formed by the acrosome and nucleus; this is followed by the flagellum, which is formed by the centriolar adjunct, an axoneme with a 9 + 9 + 2 microtubule pattern, two mitochondrial derivatives, and two accessory bodies. The acrosome is formed by the acrosomal vesicle and perforatorium. The nucleus is filled with compact chromatin with many areas of thick and non-compacted filaments. Both mitochondrial derivatives have the same shape and diameters. The presence of sperm bundles in sexually mature males differentiates C. victima from other ants; however, the similarities in the sperm ultrastructure support the monophyly of this insect group.

Spermatozoon ultrastructure of hangingflies, Bittacus strigosus and Bittacus stigmaterus.

In the present study, spermatozoon ultrastructure was documented in two species of hangingflies, Bittacus strigosus Hagen (Mecoptera: Bittacidae) and B. stigmaterus Say. Structures considered important to phylogenetic assessment that were observed in B. strigosus and B. stigmaterus included a short bilayered acrosome, elongated nucleus, tube-like glycocalyx, centriole adjunct material, accessory bodies, two mitochondrial derivatives, extra axonemal rods, globular units, and 9+2 arrangement of microtubules in the axoneme. Comparisons were made to Bittacus planus Cheng, which was previously examined by electron microscopy ( Xie and Hua 2010 ). Similarities among the ultrastructural characteristics of the three Bittacus species support the monophyly of this genus. Displacement of a mitochondrial derivative by an accessory body was documented for the first time. This paper includes clarifications on differences between accessory bodies and extra axonemal rods, which are issues important to phylogenetic placement.

Spermatozoon Ultrastructure of Hangingflies,Bittacus strigosusandBittacus stigmaterus

In the present study, spermatozoon ultrastructure was documented in two species of hangingflies, Bittacus strigosus Hagen (Mecoptera: Bittacidae) and B. stigmaterus Say. Structures considered important to phylogenetic assessment that were observed in B. strigosus and B. stigmaterus included a short bilayered acrosome, elongated nucleus, tube-like glycocalyx, centriole adjunct material, accessory bodies, two mitochondrial derivatives, extra axonemal rods, globular units, and 9 2 arrangement of microtubules in the axoneme. Comparisons were made to Bittacus planus Cheng, which was previously examined by electron microscopy (Xie and Hua 2010). Similarities among the ultrastructural characteristics of the three Bittacus species support the monophyly of this genus. Displacement of a mitochondrial derivative by an accessory body was documented for the first time. This paper includes clarifications on differences between accessory bodies and extra axonemal rods, which are issues important to phylogenetic placement.

Ultrastructural Characteristics of Spermiogenesis inRhynchophorus ferrugineus(Coleoptera: Curculionidae)

Abstract The red palm weevil (RPW), Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae), is a pest that is rapidly spreading across the globe. Here, the ultrastructure of R. ferrugineus spermatogenesis and sperm are described. The histology of the testis, sperm ultrastructure, and spermiogenesis were investigated using light and transmission electron microscopy. The differentiation of spermatids was observed to occur within spermiogenetic cysts. Inside each cyst, the spermatids were at the same stage of maturation. During early stages, mitochondria aggregated, fused, and elongated beside the growing flagellar axoneme, while the proacrosome transformed into a triple-layered acrosome, with a perforatorium, acrosomal vesicle, and extra-acrosomal layer. The centriolar adjunct was present in early spermatids but was absent from later spermatid stages and sperm. The sperm's tail displayed a typical axoneme with a 9 + 9 + 2 microtubule arrangement, 2 mitochondrial derivatives of unequal size, and 2 acc...

Giant spermatozoa and a huge spermatheca: A case of coevolution of male and female reproductive organs in the ground louse Zorotypus impolitus (Insecta, Zoraptera)

The male and female genital apparatus of the recently discovered ground louse Zorotypus impolitus were examined using light and electron microscopy. The rounded testes and a large seminal vesicle are connected with a complex of four accessory glands by a long tapering ejaculatory duct. Two accessory glands have the same whitish coloration, whereas the third one is pale blue, and the elongated and cylindrical fourth one translucent. The sperm are the largest known in Hexapoda, 3mm long and 3μm wide, with a volume of ca. 21,000μm3; the ratio between the diameter of the axoneme and the width of the main body of the sperm ranges between 1:10 and 1:13. The exceptional width of the spermatozoa is due to an extreme enlargement of the mitochondrial derivatives and accessory bodies. A single sperm is contained in a small globular spermatophore (100μm). The highly unusual external transfer correlates with an atypical mating behavior. The male produces several to many spermatophores during the mating process. As in other zorapterans the ovaries are panoistic and the eggs bear two micropyles. An exceptionally large apical spermathecal receptacle is present; it is connected with the vagina by a long spermathecal duct, which varies structurally along its course. A correlation between the sperm size and the size of the spermatheca is likely. Ultrastructural features of different species support two strikingly different models of male and female reproductive apparatus in the small order Zoraptera. This is in stark contrast to the extreme uniformity of their external morphology. It is likely that sexual selection played a decisive role in the evolution of the reproductive system.

The spermatozoon of Mengenilla moldrzyki (Strepsiptera, Mengenillidae): Ultrastructure and phylogenetic considerations

Even though the spermatozoa of several strepsipteran species were described earlier, no data were available for the basal family Mengenillidae. Well-fixed material of the recently described Tunisian species Mengenilla moldrzyki was used for a detailed examination of the sperm ultrastructure. The total length is c. 30 μm. The head region contains a conical acrosome vesicle (0.3-0.35 μm) and an elongated nucleus (7.3 μm) with dense chromatin. Some granular material along with a uniformely dense centriole adjunct and two mitochondrial derivatives are visible at the posterior end of the nucleus. The material of the centriole adjunct does not extend along the flagellum and accessory bodies are absent. The mitochondrial derivatives are elongated structures crossed by a longitudinal crista but lacking parallel transverse cristae and paracrystalline material in the dense matrix. The mitochondrial derivatives gradually reduce their size and end at the most posterior tail region. The flagellar axoneme has a 9 + 9 + 2 pattern and originates beneath the nucleus. In the terminal tail region the axoneme gradually disintegrates. Despite the extreme specialization of the endoparasitc group, strepsipteran spermatozoa are mostly characterized by plesiomorphies. The pattern within the order is largely uniform, but Mengenilla displays several apomorphic features compared to the presumptive strepsipteran groundplan (e.g., absence of crystallizations and cristae in the mitochondrial derivatives). The subdivision of the intertubular material into two compartments with a dense beak-like structure adhering to the tubular wall supports a clade Coleopterida ( = Strepsiptera + Coleoptera) + Neuropterida.

Sperm morphology of Trichospilus diatraeae and Palmistichus elaeisis (Hymenoptera: Chalcidoidea: Eulophidae)

In this study, the sperm morphology of the parasitoids Trichospilus diatraeae and Palmistichus elaeisis (Eulophidae) was investigated using light and transmission electron microscopy. In the two species, the sperm are spiral along their entire length and measure about 130μm and 195μm in length, respectively. The head region consists of the acrosome and nucleus. The acrosome is composed of an acrosomal vesicle and, in P. elaeisis, a perforatorium. In both species, an extracellular layer in which several filaments are radiated covers the acrosome and the anterior nuclear region. The nuclei are filled with homogeneous and compact chromatin and measure about 50μm in length in P. elaeisis and 20μm in T. diatraeae. The flagellum consists of an axoneme with the 9+9+2 microtubule arrangement spiraled in a long helix, two mitochondrial derivatives coiling around the axoneme and, in P. elaeisis, two accessory bodies. In T. diatraeae were observed transverse striations throughout the central region of the axoneme, whereas the central pair of microtubules was rarely observed. In the final flagellar region in T. diatraeae, different from P. elaeisis, one mitochondrial derivative ends well before the other and both end before the axoneme. The sperm of these two species exhibit features that discriminate one species from each other, as well as characteristics suggest that Eulophidae is closely related to Trichogrammatidae and both of these families are more similar to Eurytomidae than Agaonidae.

Sperm morphology and phylogeny of lagriids (Coleoptera, Tenebrionidae)

The systematics of tenebrionids remain unclear, principally at the subfamily level, as is the case of the Lagriinae. Considering that sperm morphology has contributed to the various insect group phylogenies, in this work we describe the structure and ultrastructure of these cells in Lagria villosa. Sperm in this species exhibit a strong morphological similarity to those of Tenebrio molitor and Tribolium castaneum, the only two species of Tenebrionidae with previously described sperm. In tenebrionids, the flagellar components offer good diagnostic characters, e.g. the symmetry of mitochondrial derivatives in L. villosa differentiates sperm of this species from those of Te. molitor and Tr. castaneum. However, the lateral association of the nucleus with flagellar components, the form of accessory bodies, and the presence of material connecting the axoneme to the accessory bodies and mitochondrial derivatives indicate that the three species form a sister group. Therefore, the sperm morphology of L. villosa support lagriid beetles as a subfamily (Lagriinae) of Tenebrionidae.

Morphology of the male reproductive system and sperm ultrastructure of the egg parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera, Platygastridae)

Gryon pennsylvanicum is a platygastrid hymenopteran that has lately received increasing attention in Europe due to its possible use in biological control of the conifer seed bug pest Leptoglossus occidentalis. Here the male reproductive system and the spermatogenesis of this species, along with those of Gryon muscaeformis, are examined ultrastructurally for the first time. The male genital system is formed by a pair of testes, each containing only one follicle, a pair of accessory glands and deferent ducts connected to a single ejaculatory duct. All the stages of spermatogenesis are described in detail. Characteristic features of the Gryon spp. sperm, which are 100 μm long, are the presence of a polygonal nucleus, only one mitochondrial derivative, the occurrence of the centriole adjunct and a typical insect 9 + 9 + 2 flagellar axoneme. The single derivative, however, results from a process in which one of the two mitochondria is lost during spermiogenesis. Unlike in other insects, two centrioles occur in spermatids as a consequence of the ameiotic parthenogenesis. These characteristics stand as a valuable tool for phylogenetic inferences. Furthermore this study suggests a useful strategy for laboratory mass rearing.