Sperm of Doradidae (Teleostei: Siluriformes)

Spermatic characteristics were studied in 10 species representing several distinct groups within the catfish family Doradidae. Interestingly, different types of spermatogenesis, spermiogenesis and spermatozoa are correlated with intrafamilial groups previously proposed for Doradidae. Semi-cystic spermatogenesis, modified Type III spermiogenesis, and biflagellate sperm appear to be unique within Doradidae to the subfamily Astrodoradinae. Other doradid species have sperm with a single flagellum, cystic spermatogenesis, and spermiogenesis of Type I (Pterodoras granulosus, Rhinodoras dorbignyi), Type I modified (Oxydoras kneri), or Type III (Trachydoras paraguayensis). Doradids have an external mode of fertilization, and share a few spermatic characteristics, such as cystic spermatogenesis, Type I spermiogenesis and uniflagellate sperm, with its sister group Auchenipteridae, a family exhibiting sperm modifications associated with insemination and internal fertilization. Semi-cystic spermatogenesis and biflagellate spermatozoa are also found in Aspredinidae, and corroborate recent proposals that Aspredinidae and Doradoidea (Doradidae + Auchenipteridae) are sister groups and that Astrodoradinae occupies a basal position within Doradidae. The co-occurrence in various catfish families of semi-cystic spermatogenesis and either biflagellate spermatozoa (Aspredinidae, Cetopsidae, Doradidae, Malapturidae, Nematogenyidae) or uniflagellate sperm with two axonemes (Ariidae) reinforces the suggestion that such characteristics are correlated. Semi-cystic spermatogenesis and biflagellate sperm may represent ancestral conditions for Loricarioidei and Siluroidei of Siluriformes as they occur in putatively basal members of each suborder, Nematogenyidae and Cetopsidae, respectively. However, if semi-cystic spermatogenesis and biflagellate sperm are ancestral for Siluriformes, cystic spermatogenesis and uniflagellate sperm have arisen independently in multiple lineages including Diplomystidae, sister group to Siluroidei.     

Spermiogenesis and spermatozoal ultrastructure in Trichomycteridae (Teleostei: Ostariophysi: Siluriformes)

Spadella, M.A., Oliveira, C. and Quagio‐Grassiotto, I. 2009. Spermiogenesis and spermatozoal ultrastructure in Trichomycteridae (Teleostei: Ostariophysi: Siluriformes). —Acta Zoologica (Stockholm) 91 : 373–389. Siluriformes comprises the most diverse and widely distributed ostariophysan group, a fish assemblage that includes about three quarters of the freshwater fish of the world. In this study, the ultrastructural characterization of spermiogenesis and spermatozoa in specimens of Copionodontinae (the sister group to all other trichomycterids), Trichomycterinae (a derived trichomycterid group), and Ituglanis (a genus not assigned to any trichomycterid subfamily) is presented. The comparative analyses of the data show that trichomycterid species share six of seven analyzed spermiogenesis characters, reinforcing the monophyly of the group. Analyses of trichomycterid sperm ultrastructure showed that the species studied share the same character states for nine of seventeen characters analyzed. Copionodon orthiocarinatus and Ituglanis amazonicus each share more ultrastructural characters with species of Trichomycterus than with one another. Regarding the families of Loricarioidea, the species of Trichomycteridae share more characters of spermatogenesis, spermiogenesis, and sperm with representatives of the families Callichthyidae, Loricariidae, and Scoloplacidae than with Nematogenyidae, its hypothesized sister group. With the exception of the family Nematogenyidae, the character similarities observed reinforce the monophyly of the superfamily Loricarioidea.     

A phylogenetic study of the neotropical catfish family Cetopsidae (Osteichthyes, Ostariophysi, Siluriformes), with a new classification

A hypothesis on the phylogenetic relationships of the neotropical catfish family Cetopsidae is proposed on the basis of the parsimony analysis of 127 morphological characters and most of the species currently recognized. The family and its two recognized subfamilies, the Cetopsinae and Helogeninae, are corroborated as monophyletic, in agreement with recent studies. Previously proposed classifications of the Cetopsinae, however, were found to be poorly representative of the phylogenetic relationships within the subfamily. Major generic rearrangements are implemented in order that the classification of the Cetopsinae reflects the phylogenetic hypothesis. Pseudocetopsis Bleeker (1862) was found to be polyphyletic and to include several disjunct lineages. One of these lineages, recently named as the genus Cetopsidium Vari, Ferraris, and de Pinna (2005), is the sister group to the rest of the Cetopsinae. Denticetopsis Ferraris (1996) is the next sister group to the remainder of the Cetopsinae. The remaining species of the Cetopsinae belong to one of two sister genera, Paracetopsis Bleeker (1862) and Cetopsis Spix and Agassiz (1829). The latter genus includes species formerly assigned to Hemicetopsis Bleeker (1862), Bathycetopsis Lundberg and Rapp Py‐Daniel (1994) and Pseudocetopsis Bleeker (1862). Continued recognition of Hemicetopsis and Bathycetopsis would have required the creation of several additional new genera for various species previously in Pseudocetopsis that form a series of sister groups to a clade composed of Cetopsis oliveirai (Lundberg and Rapp Py‐Daniel, 1994), C. coecutiens (Lichtenstein, 1819) and C. candiru (Spix and Agassiz, 1829). Cetopsis oliveirai is a highly paedomorphic species that displays surprising similarities with conditions in juvenile specimens of C. coecutiens, a species that attains a large body size. Such similarities are not evident in adult specimens of the latter species. A new classification is proposed, within which the subfamily Cetopsinae consists of three tribes, the Cetopsidiini, the Cetopsini and the Denticetopsini. The results of the study form the basis for a discussion of the phylogenetic position of the family within the Siluriformes, the phylogenetic biogeography of the Cetopsidae, paedomorphosis and gigantism in the family, and the effect of different semaphoronts on the intrafamilial phylogeny. Journal compilation © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 150 , 755–813. No claim to original US government works.     

Sperm ultrastructure and a new type of spermiogenesis in two species of Pimelodidae, with a comparative review of sperm ultrastructure in Siluriformes (Teleostei: Ostariophysi)

During spermiogenesis, the spermatids of the pimelodid species Pimelodus maculatus and Pseudoplatystoma fasciatum show a central flagellum development, no rotation of the nucleus, and no nuclear fossa formation, in contrast to all previously described spermatids of Teleostei. These characteristics are interpreted as belonging to a new type of spermiogenesis, named here type III, which is peculiar to the family Pimelodidae. In P. maculatus and P. fasciatum, spermatozoa possess a spherical head and no acrosome; their nucleus contains highly condensed, homogeneous chromatin with small electron-lucent areas; and a nuclear fossa is not present. The centriolar complex lies close to the nucleus. The midpiece is small, has no true cytoplasmic channel, and contains many elongate and interconnected vesicles. Several spherical to oblong mitochondria are located around the centriolar complex. The flagellum displays the classical axoneme (9+2) and no lateral fins. Only minor differences were observed among the pimelodid species and genera. Otherwise, spermiogenesis and spermatozoa in the two species of Pimelodidae studied exhibit many characteristics that are not found in other siluriform families, mainly the type III spermiogenesis.     

Spermiogenesis and spermatozoa ultrastructure in Salminus and Brycon, two primitive genera in Characidae (Teleostei: Ostariophysi: Characiformes)

In Salminus, spermiogenesis is cystic and gives origin to a type I aquasperm. Spermatid differentiation is characterized by chromatin condensed into thick fibres, nuclear rotation, nuclear fossa formation, cytoplasmic channel formation, mitochondrial fusion producing long and ramified mitochondria, and the presence of several membranous concentric rings around the plasma membrane that encircles the cytoplasmic channel. In Salminus and Brycon, spermatozoa are very similar. They exhibit a spherical nucleus and chromatin condensed into fibre clusters, and a deep nuclear fossa. They show a long midpiece with few elongate mitochondria at the initial region and a cytoplasmic channel completely encircled by one or two membranous concentric rings. The flagellar axis is perpendicular to the nucleus and exhibits the classic axoneme (9 + 2). The very strong similarity observed between Salminus and Brycon spermatozoa supports the hypothesis that these subfamilies are likely to have a monophyletic origin.     

An assessment approach for application of spermatic data in phylogenetic analyses: within the genus Moenkhausia Eigenmann, 1903 (Characiformes: Characidae)

Spermiogenesis and sperm ultrastructure from 21 species of Moenkhausia and others related genera are described. To evaluate the phylogenetic signals, 18 unordered characters were utilized in implied weighting analysis through the program TNT 1.1. Four variations of spermiogenesis were found. In the earliest spermatids, the nucleus can be positioned lateral, eccentric, strongly eccentric or nearly medial in relation to the distal centriole. The nuclear rotation can be present or absent. These spermiogenesis processes are related or intermediate to Type I and Type III. Taking into account the degrees of nuclear rotation during the spermiogenesis and other characteristics, distinct forms of spermatozoa are observed among the species analyzed. The phylogenetic analysis yielded a single most parsimonious tree with fit value 2.70000 and the topology obtained founds Moenkhausia as non‐monophyletic. However, some hypothesis of relationships previously proposed viz the clade 20, which contains the type species Moenkhausia xinguensis, is recovered herein. This clade is supported by five synapomorphies, and it allows the supposition that these species constitute a monophyletic group. The whole topology is presented and discussed.     

Ultrastructure of spermiogenesis in the Cottonmouth,Agkistrodon piscivorus (Squamata: Viperidae: Crotalinae)

To date multiple studies exist that examine the morphology of spermatozoa. However, there are limited numbers of data detailing the ontogenic characters of spermiogenesis within squamates. Testicular tissues were collected from Cottonmouths (Agkistrodon piscivorus) and tissues from spermiogenically active months were analyzed ultrastructurally to detail the cellular changes that occur during spermiogenesis. The major events of spermiogenesis (acrosome formation, nuclear elongation/DNA condensation, and flagellar development) resemble that of other squamates; however, specific ultrastructural differences can be observed between Cottonmouths and other squamates studied to date. During acrosome formation vesicles from the Golgi apparatus fuse at the apical surface of the nuclear membrane prior to making nuclear contact. At this stage, the acrosome granule can be observed in a centralized location within the vesicle. As elongation commences the acrosome complex becomes highly compartmentalized and migrates laterally along the nucleus. Parallel and circum‐cylindrical microtubules (components of the manchette) are observed with parallel microtubules outnumbering the circum‐cylindrical microtubules. Flagella, displaying the conserved 9 + 2 microtubule arrangement, sit in nuclear fossae that have electron lucent shoulders juxtaposed on either side of the spermatids basal plates. This study aims to provide developmental characters for squamates in the subfamily Crotalinae, family Viperidae, which may be useful for histopathological studies on spermatogenesis in semi‐aquatic species exposed to pesticides. Furthermore, these data in the near future may provide morphological characters for spermiogenesis that can be added to morphological data matrices that may be used in phylogenetic analyses. J. Morphol. 2010. © 2009 Wiley‐Liss, Inc.     

Inhibition of Spermiogenesis of Eupyrene Spermatozoa by Elevated,Sublethal Temperatures During Pupal-Adult Development of the Bertha Armyworm,Mamestra con figurata Wlk. (Lepidoptera,Noctuidae)

Summary

Eupyrene spermiogenesis and spermatozoa production in Mamestra configurata Walker were inhibited by temperatures >24° C during a “critical period” of about 7 days during the first half of post-diapause pupal-adult development. The critical period coincided with the appearance of early-stage eupyrene spermatids. If temperatures >24° C occurred during the critical period, eupyrene spermatozoa production was reduced, the result of irreversible autolysis of the early- and mid-stage eupyrene spermatids. Each day of exposure to 25 or 27.5° C during the critical period reduced the number of eupyrene cysts with spermatozoa on average by 12 to 14%. There were no observable effects on eupyrene spermiogenesis and spermatozoa production of exposing post-diapausing pupae to 25 or 27.5° C before or after the critical period. Apyrene spermatogenesis was not affected by 25 or 27.5° C.

Exposure of pupae to 25°or 27.5° C during diapause had no apparent effect on eupyrene spermiogenesis and spermatozoa production. Meiosis usually was not detected among the eupyrene cysts with lalje primary spermatocytes until after diapause, indicating that meiosis is suppressed during diapause. By providing a meiotic block, diapause governs the time of onset of the temperature-sensitive critical period of spermiogenesis. In nature, male pupae of M. configurata in diapause are protected from sterilizing temperatures in the soil during August and post-diapause developing pupae pass through the critical period of spermiogenesis in spring (April to June) when soil temperatures throughout the range of M. configurata in Canada are well below 25° C. The distribution of M. configurata in the northern region of the temperate zone may in part be attributable to the sensitivity of spermatogenesis to relatively mild temperatures.     

Differential staining and microchromosomal variation in karyotypes of four Brazilian species of Tupinambinae lizards (Squamata: Teiidae)

Kayotypes of four neotropical teiid lizard species (Tupinambinae) were herein studied after conventional as well as silver staining and CBG-banding: Crocodilurus amazonicus (2n = 34), Tupinambis teguixin (2n = 36), Tupinambis merianae and Tupinambis quadrilineatus (2n = 38). The karyological data for T. quadrilineatus as well as those obtained using differential staining for all species were unknown until now. The karyotypes of all species presented 12 macrochromosomes identical in morphology, but differed in the number of microchromosomes: 22 in C. amazonicus, 24 in T. teguixin and 26 in T. quadrilineatus and T. merianae. The Ag-NOR located at the secondary constriction at the distal end of pair 2 is shared by all species, contrasting with the variability observed for this character in species of the related Teiinae. CBG-banding revealed a species-specific pattern in T. quadrilineatus with conspicuous interstitial C-blocks at the proximal region of the long arm of pair 4 and the whole heterochromatic short arm of pair 6. The karyological data reported here corroborates the relationship hypothesis obtained for Tupinambis based on molecular characters. T. teguixin presents the putative ancestral karyotype for the genus with 2n = 36 whereas T. merianae and T. quadrilineatus exhibit 2n = 38, due to an additional pair of microchromosomes.     

Structure and ultrastructure of spermatozoa and spermiogenesis in three species of Lucilia Robineau‐desvoidy, 1830 (Diptera: Calliphoridae)

Morphology of male internal reproductive organs, spermatozoa, and spermiogenesis of the blow‐flies Lucilia cuprina, Lucilia eximia, and Lucilia peruviana is first described here, using light and transmission electron microscopy. Spermiogenesis follows the characteristics described for others insect species. The spermatozoa of L. cuprina are similar to those described for other Brachycera. However, in L. eximia and L. peruviana, some differences were found. In L. cuprina and L. eximia species, the spermatozoa are long and thin, measuring about 211 μm and 146 μm in length, of which the head region measures approximately 19 μm and 17 μm, respectively. A polymorphism was observed in L. cuprina and L. eximia spermatozoa. In all three species, the head includes a monolayered acrosome with electron‐lucent material. The shape of the nucleus, in cross sections, varies from circular to oval with completely condensed chromatin. Implantation of the axoneme was observed in the middle region of the nucleus, known as the “peg” region. In the next region, the beginning of two mitochondrial derivatives of similar diameter and different lengths in L. cuprina and only one in L. eximia and L. peruviana was observed. In the overlap region, the following structures were observed: nucleus, centriolar adjunct, mitochondrial derivatives, and axoneme. The axoneme is of a conventional insectan type with a 9 + 9 + 2 microtubular arrangement. The male internal reproductive tract consists of testis, deferent ducts, a strongly developed seminal vesicle, accessory glands, and ejaculatory duct. These features are consistent with the structural diversity of the dipteran reproductive tract and spermatozoa, comprising an essential tool for understanding the complex variations found in the Diptera. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.     

Ultrastructure of spermiogenesis in Plagioscion squamosissimus (Teleostei, Perciformes, Sciaenidae)

Spermiogenesis in Plagioscion squamosissimus occurs in cysts. It involves a gradual differentiation process of spermatids that is characterized mainly by chromatin compaction in the nucleus and formation of the flagellum, resulting in the spermatozoa, the smallest germ cells. At the end of spermiogenesis, the cysts open and release the newly formed spermatozoa into the lumen of the seminiferous tubules. The spermatozoa do not have an acrosome and are divided into head, midpiece, and tail or flagellum. The spermatozoa of P. squamosissimus are of perciform type with the flagellum parallel to the nucleus and the centrioles located outside the nuclear notch.     

Comparative morphology of the reproductive system of seven species of ostariophysan fishes from the upper Das Velhas River,Brazil

The success of fishes in different environments is related with the variation of reproductive strategies developed by the systematic group, which is reflected in the morphology of the reproductive system and can have ecological and evolutionary implications. This study comparatively analyzed the morphological characteristics of the male and female reproductive systems of ostariophysan fish species from the upper Das Velhas River in the São Francisco River basin, Brazil. In order to accomplish this, 393 specimens belonging to seven fish species were sampled between April 2010 and June 2015 for histological, ultrastructural, histochemical, and morphometric analyses. All the species examined have anastomosing tubular testes with unrestricted distribution of spermatogonia. Astyanax bimaculatus , A. fasciatus , A. scabripinnis , and Harttia torrenticola had their spermatozoa embedded in a glycoprotein secretion within the tubule lumen. Most species had type I spermiogenesis, whereas Rhamdia quelen had type III spermiogenesis. While all females examined had asynchronous oocyte development, there were remarkable morphological, histochemical, and morphometric differences in the ovarian follicles and enveloping layers. Hoplias malabaricus and H. torrenticola , which exhibit parental care behaviour, had a significantly larger diameter of vitellogenic oocytes and larger spermatozoa nuclei. Apareiodon ibitiensis , H. torrenticola , and A. scabripinnis , species that have rheophilic preferences, exhibited a thicker zona radiata than the other species examined. The follicular cells of R. quelen and H. torrenticola were columnar and produced a jelly coat and mucosubstances, respectively. The females of the seven fish species studied show a correlation of the reproductive strategies with the reproductive system morphology, while males retained more similar morphological characteristics between species. J. Morphol. 278:170–181, 2017. © 2016 Wiley Periodicals,Inc.     

Spermiogenesis in the spider,Pisaurina Sp.: A fine structure study

A fine structure study of spermatids and spermatozoa of the spider, Pisaurina sp. demonstrates that early spermiogenesis is similar to other flagellate spermatozoa. An acrosome forms from a Golgi-derived, acrosomal vesicle, a perforatorium indents acromosome and nucleus, a flagellum with a three-plus-nine tubule substructure is formed and nuclear chromatin condenses during spermiogenesis. Divergence from typical spermatozoa includes the presence of a three-tubule substructure of the central flagellar shaft, progressive rounding-up of late spermatids with concomitant incorporation of previously formed flagellum. This evidence is presented in terms of its possible functional significance in fertilization and gamete fusion in spiders.     

Spermiogenesis in three species of cicadas (Hemiptera: Cicadidae)

Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero‐lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante‐acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.     

Ultrastructure of the semicystic spermatogenesis in the South American freshwater characid Hemigrammus marginatus (Teleostei,Characiformes)

Semicystic, a rare type of spermatogenesis, was detected in the characid Hemigrammus marginatus and characterized by cysts hatching during the spermatid phase and maturation of the spermatozoa being completed at the lumen of the anastomosed seminiferous tubules. Primary spermatogonia, or type A, are distributed along the entire length of the seminiferous tubules, in an unrestricted spermatogonial pattern. H. marginatus spermiogenesis is included in type I, mainly characterized by presence of nucleus rotation. During this process, a vesicle resembling the acrosomal vesicle is visualized at the anterior region close to the nucleus of the early spermatids, however this structure did not remain in the spermatozoa. In H. marginatus, the spermatozoon is uniflagellated, primitive, type I aquasperm, with a rounded head, a short midpiece and a long flagellum with the axoneme in a 9 + 2 microtubules arrangement and no lateral fins. Residual spermatozoa are reabsorbed by Sertoli cells. Unusual biflagellate spermatozoa with three long cytoplasmatic projections originating in the midpiece are rarely observed and have not been registered in other characiforms. Ultrastructural characteristics of the spermatogenesis and spermatozoa observed in the present work provide important subsidies to systematic and phylogeny studies of Characidae fishes included in Incertae sedis groups, such as H. marginatus.     

A novel function for the presenilin family member <Emphasis Type="Italic">spe-4</Emphasis>: inhibition of spermatid activation in <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>.

Background  

Sperm cells must regulate the timing and location of activation to maximize the likelihood of fertilization. Sperm from most species, including the nematode Caenorhabditis elegans, activate upon encountering an external signal. Activation for C. elegans sperm occurs as spermatids undergo spermiogenesis, a profound cellular reorganization that produces a pseudopod. Spermiogenesis is initiated by an activation signal that is transduced through a series of gene products. It is now clear that an inhibitory pathway also operates in spermatids, preventing their premature progression to spermatozoa and resulting in fine-scale control over the timing of activation. Here, we describe the involvement of a newly assigned member of the inhibitory pathway: spe-4, a homolog of the human presenilin gene PS1. The spe-4(hc196) allele investigated here was isolated as a suppressor of sterility of mutations in the spermiogenesis signal transduction gene spe-27.     

Spermiogenesis and spermatozoon ultrastructure of the cestode Mosgovoyia ctenoides (Cyclophyllidea: Anoplocephalidae), an intestinal parasite of Oryctolagus cuniculus (Lagomorpha: Leporidae)

Ultrastructural characters in spermiogenesis and spermatozoa are considered important tools to elucidate the phylogenetic relationships within the Platyhelminthes. In the Anoplocephalidae, ultrastructural data refer to the spermatozoon of 14 species, whereas data on spermiogenesis refer to only 7 species. The present study focused on the spermiogenesis and spermatozoon of the anoplocephalid cestode Mosgovoyia ctenoides, as revealed by transmission electron microscopy. Type IV spermiogenesis was detected, beginning with the formation of a differentiation zone containing 2 centrioles, with a centriolar adjunct and vestigial striated rootlets. Different forms of the latter character have been described in other anoplocephalids. This study supports spermiogenesis of type IV as the most frequent in the Anoplocephalidae and confirms the presence of a centriolar adjunct in yet another type IV spermiogenesis species. The spermatozoon of M. ctenoides possesses 1 axoneme of the 9+ '1' trepaxonematan type, 2 crestlike bodies, dense plates, and granules of electron-dense cytoplasmic material, nucleus, and twisted cortical microtubules. It was again confirmed that the presence of granular material and the absence of both a periaxonemal sheath and intracytoplasmic walls are constant characters in the spermatozoa of all the Anoplocephalinae.     

Cetopsis varii,a new species of whale catfish (Siluriformes: Cetopsidae) from the Meta Basin,Colombia

Cetopsis varii sp. nov. Cetopsidae (Cetopsinae) is described from the Río Meta basin in eastern Colombia, at middle portions of the Río Orinoco basin. The new species differs from congeners by a combination of features: the absence of a humeral spot, presence of eye, conical teeth on vomer and dentary and rounded posterior nares, along with details of body, dorsal and caudal‐fin pigmentation. The osteology of the new species is investigated through high‐resolution X‐ray computed tomography and cleared and stained specimens. Data thus obtained are used to code the new species for character states utilized in a previous phylogenetic analysis of Cetopsidae. Analysis of the expanded matrix shows that C. varii is the sister group to C. orinoco.