Spermatic Cysts Research Articles

The sperm ultrastructure of Spermophagus kuesteri Schilsky, 1905 (Chrysomelidae, Bruchinae) and considerations on the relationships of Cucujiformia superfamilies

The sperm ultrastructure of the bean-weevil Spermophagus kuesteri (Bruchinae) was studied to verify the congruence of the new position of the subfamily within Chrysomelidae. The results indicated a positive answer to the question supporting a close relationship between Chrysomelidae and Curculionidae, a finding confirmed also by molecular data. Moreover, the sperm morphology of Divales cinctus, a member of Melyridae (Cleroidea) allowed to confirm the different sperm organization between members of this superfamily and Phytophaga (Chrysomeloidea + Curculionoidea). While studying the spermiogenesis of S. kuesteri, some sperm cysts showed aberrant cells provided with two flagella in the same plasma membrane. These aberrant sperm could be the result, during early spermiogenesis, of irregular processes involving the canal rings between spermatids.

Life-cycle traits in the demosponge Hymeniacidon perlevis in a land-based fish farm.

The demosponge Hymeniacidon perlevis is characterized by wide geographic distribution and great adaptability to numerous and highly variable climatic and hydrological conditions. Indeed, the species can colonize many different environments, including several unusual ones, such as concrete drainage conduits of a marine land-based fish farm plant. This research aimed to enhance existing knowledge on the reproductive cycle and growth performance of H. perlevis while also evaluating the impact of a controlled supply of trophic resources, wastewater flow and constant water temperature on these biological traits. Specimens included in this one-year study inhabited drainage conduits of a land-based fish farm. The approach included measurements of sponge biomass and occurrence and abundance of reproductive elements across different seasons and environmental parameters, such as fish biomass, trophic resources, and wastewater flow. Sponge growth and reproductive elements, including oocytes, spermatic cysts, and embryos, were measured monthly in sponges positioned in the drainage conduit, thus with different trophic resources but with constant water temperature. Finally, we used generalized additive models to describe variables that contribute the most to the growth of sponges. Growth performance showed marked variations during the study period. The highest increase in sponge volume was observed from August/September to January/March. The volume of sponges was principally determined by the reduction of reared fish biomass and the increase of pellet amount and wastewater flow. Sponge specimens exhibited an active state during the entire study, as proven by the occurrence of recruits. However, sexual elements were only sporadically observed, thus not permitting the recognition of a true sexual cycle. The results of the present study confirmed that H. perlevis exhibits high flexibility and adaptability to the differential, and somewhat extreme, environmental conditions. Indeed, this species can live, grow and reproduce in the drainage conduits of the fish farm, where the species face constant darkness, water temperature and continuous nutritional supply. In such conditions, H. perlevis display an active state during the entire year, while avoiding stages of decline and long dormancy usually observed in wild populations. It seems plausible that stable environmental conditions induce an almost continuous sexual phase, probably under the control of endogenous factors. No asexual elements were detected, although it was impossible to exclude the contribution of asexual reproduction in the origin of the newly settled sponges, which were repeatedly detected throughout the study. The growth performance seemed linked to the fish farm conditions, thus providing useful indications on the best maintenance conditions for H. perlevis in land-based integrated multitrophic systems, where the species could be used for wastewater treatment.

Cellular mechanisms of the lufenuron growth regulator in adults of Anthonomus grandis (Coleoptera: Curculionidae)

Abstract Growth-regulating insecticides are used for several cotton pests when immature, and although not registered for Anthonomus grandis, their use causes a satisfactory population reduction in adults. However, it is not known which mechanisms are involved in this reduction. Thus, we studied which tissue and cellular changes may be involved in this process. Adults were fed with flower buds treated with lufenuron (4 ml commercial product /l) for 24 h. Then, the histology of the gonads, oxidative stress and apoptosis were evaluated after periods of 24 h and 48 h. Our study revealed that lufenuron activates the oxidative stress pathway in A. grandis, causing significant changes at the cellular level. These changes may have been caused by stimulation of the production of oxygen ions, free radicals and hydrogen peroxides, resulting in an increase in lipid peroxidation 48 h after treatment. These effects were confirmed by the presence of histopathologies in the gonads of this pest such as disorganization of the follicular cell epithelium, reduction of the yolk, disappearance of the germinal vesicle, reduction of sperm bundles and cysts. Such alterations injured the gonads and impaired tissue homeostasis. It is concluded that together these factors lead to a desirable population reduction when it comes to managing the pest in the field, because the aim is to keep it below the control level. In addition to this desired effect, it is worth noting that lufenuron is safer when compared to other commonly used products, another feature that makes its use quite interesting.

The sperm ultrastructure of members of basal Tenebrionoidea (Coleoptera)

The sperm ultrastructure of some beetles of Tenebrionoidea was studied with particular attention to those of the Ripiphoridae, Mordellidae, and Meloidae. These three groups are often thought to form a clade, which is the sister group of the remaining Tenebrionoidea. The testes of the two former families have thinner but longer spermatic cysts containing fewer and longer sperm. Within each cyst all sperm cells have the same orientation, but cross sections showed that the orientation of the axonemes alternate between adjacent cysts, possibly due to the cysts bending on themselves. In both families the sperm has a bilayered acrosome and the flagellum, which shows mitochondrial derivatives starting laterally to the nuclear base, has a typical 9 + 9+2 axoneme with accessory tubules provided with 16 protofilaments in their wall, and well-structured triangular shaped accessory bodies. In Mordellistena sp (Mordellidae) sperm, both mitochondrial derivatives and accessory bodies are somewhat asymmetrical. Moreover, the flagellum shows a very thin and long tail end provided with only accessory tubules. Meloidae species have testes with thicker sperm cysts containing numerous shorter sperm. Within the individual cysts the sperm flagella exhibit an alternating orientation of their axonemes as consequence of a peculiar spermatogenetic process. The flagellar structure is similar to that of the above-mentioned species, but the accessory bodies are not well defined and constituted by fuzzy material. In Mylabris hieracii (Meloidae) sperm, the acrosome is flat with a conspicuous perforatorium and its nucleus has a peculiar quadrangular section. Berberomeloe majalis sperm has a large acrosome with an unusual pentagonal perforatorium. The centriolar structure of Mylabris variabilis shows a complex of dense radial links connecting the microtubular structures to the plasma membrane. These results suggest that Ripiphoridae have a closer relationship with Mordellidae than with Meloidae. These findings are in agreement with results obtained with molecular data.

Late maturity and evidence for female biennial spawning in the sea pen Pennatula aculeata (Anthozoa, Pennatulacea) in eastern Canada

AbstractLittle is known about reproduction of the sea pen Pennatula aculeata, which is found at high densities and constitutes vulnerable habitat in the Gulf of St. Lawrence, Canada. Sex ratio, size at maturity, and reproductive status were investigated for colonies collected in May, August, and October 2015 along the Gaspé Peninsula. Reproductive status was assessed by histological determination of gamete sex and maturity and by stereomicroscope measurement of the diameters of the leading cohort of oocytes (LCO) or sperm cysts of histologically mature colonies. Colonies were gonochoric, with a sex ratio of 1:1. Based on the distribution of gamete diameters in May, three groups of female and a single group of male colonies were identified. Female colonies classified in the group of LCO with the smallest diameter (0.10–0.39 mm) were shorter in total length (TL < 130 mm) than females in the other two groups of LCOs with larger diameters, and very few spawned from May to October. A major reduction in the proportion of large female colonies (TL ≥ 130 mm) belonging to the group with the largest diameter (≥0.55 mm) and of mature male colonies between May and August indicated one annual spawning event. Persistence of histologically mature (vitellogenic) female colonies classified in the two smaller oocyte diameter groups after spawning is indicative of prolonged oogenesis (at least 24 months). The fact that only approximately half of the large female colonies had ripe oocytes (diameter ≥0.55 mm) in May prior to spawning, while the other half had vitellogenic oocytes of much smaller diameter which persisted after the spawning period, suggests that they reproduce only every other year. Estimated size and age at which 50% of colonies spawned were greater in females (148 mm TL, 11–14 years) than in males (101 mm TL, 8–11 years). These reproductive characteristics may reduce resilience of P. aculeata to various anthropic stressors.

How can environmental variables affect the sexual reproduction of a tropical symbiotic sponge?

In the tropics, the marine sponge Dysidea janiae lives in obligatory symbiosis with the red macroalga Jania adhaerens. However, how this symbiosis is achieved, and how it influences the reproduction of the sponge is still unknown. We analysed the influence of environmental variables on the gametogenesis and embryogenesis of the sponge. We also investigated the histology of the reproductive propagules of the sponge over 3 years, aiming to understand how this symbiosis is established. Dysidea janiae is viviparous and gonochoristic, with a continuous but small reproductive effort. The reproductive dynamics of gametes and embryos were explained by different sets of environmental variables. Although the temperature was not directly related to the reproduction of the sponge in general, there was an increase in the density of spermatic cysts during the year when the El Nino occurred. The day length was related to the embryo dynamics, which were interpreted as an indirect effect of the increase in photosynthetic rates of the symbiont on the energetic budget of the sponge. As no algal propagules were found associated with the eggs or larvae of the sponge, the acquisition of the algae by the sponge is probably a ‘trial-and-error’ relationship after larval release. We propose that the symbiosis increases the fitness of the adult sponge, forcing the larvae to seek new macroalgae to settle on and start a new symbiosis all over again.

Reproductive Biology of Geodia Species (Porifera, Tetractinellida) From Boreo-Arctic North-Atlantic Deep-Sea Sponge Grounds

Boreo-arctic sponge grounds are essential deep-sea structural habitats that provide important services for the ecosystem. These large sponge aggregations are dominated by demosponges of the genus Geodia (order Tetractinellida, family Geodiidae). However, little is known about the basic biological features of these species, such as their life cycle and dispersal capabilities. Here, we surveyed five deep-sea species of Geodia from the North-Atlantic Ocean and studied their reproductive cycle and strategy using light and electron microscopy. The five species were oviparous and gonochoristic. Synchronous development was observed at individual and population level in most of the species. Oocytes had diameters ranging from 8 μm in previtellogenic stage to 103 μm in vitellogenic stage. At vitellogenic stages, oocytes had high content of lipid yolk entirely acquired by autosynthesis, with no participation of nurse cells. Intense vertical transmission of bacterial symbionts to the oocytes by phagocytosis through pseudopodia was observed, especially in late stages of oogenesis. The density of oocytes within the sponge tissue was on average 10 oocytes/mm2 across all species, higher than that of most temperate and tropical oviparous species studied elsewhere. Spermatic cysts were widespread over the tissue during early stages, or fused in larger cysts, around the canals in later stages, and occupying between 1.5 and 12% of the tissue in males. The reproductive season spanned similar periods for all Geodia spp.: from late spring to early autumn. During the reproductive peak of each species, between 60 and 90% of the population was engaged in reproduction for most species. Given the present hazards that threaten the boreo-arctic tetractinellid sponge grounds, it becomes crucial to understand the processes behind the maintenance and regeneration of populations of keystone deep-sea species in order to predict the magnitude of human impacts and estimate their ability to recover. The information provided in this study will be useful for developing adequate conservation strategies for these vulnerable deep-sea habitats.

Testicular structure and development of germ cells of Hypophthalmus marginatus Valenciennes 1840 (Siluriformes: Pimelodidae)

The present study was conducted to assess the testicular structure and germ cell ultrastructure of Hypophthalmus marginatus during spermatogenesis. Semen and sections of the mid-region of the testis were collected, processed, and analyzed using optical and electron microscopy. Macroscopically, the testes of H. marginatus were filiform, and the testicular parenchyma was composed of spermatogenic cells that proliferated, organized within spermatic cysts. During spermiogenesis, spermatids had no nuclear rotation. The proximal centriole was perpendicular to the distal centriole, characteristic of type III spermiogenesis. Spermatozoa were released into the lumen of the seminiferous tubules and had an ovoid head without an acrosome, condensed nucleus, and shallow nuclear fossa. The midpiece was short, with a single long flagellum. The flagellum had the typical axoneme structure, with nine pairs of peripheral and a central pair of microtubules. The thin end piece comprised only peripheral microtubules. Spermatogenesis in H. marginatus features filiform testes, cystic spermatogenesis, and type III spermiogenesis.

Spermiogenesis of the hangingfly Terrobittacus implicatus (Huang and Hua) (Mecoptera: Bittacidae).

The structure of spermatozoa is able to provide valuable characters in resolving phylogenic relationships in Metazoa, especially in insects. Such data, however, are greatly deficient in Mecoptera. Here, we studied the spermiogenesis and ultrastructure of sperm in the hangingfly Terrobittacus implicatus (Huang and Hua) using transmission electron microscopy. The results show that the spermatogenesis of T. implicatus occurs within sperm cysts, following a pattern commonly found in insects. The microtubular doublets of spermatid axoneme exhibit a hooklike projection from the B-subtubule in the early period, but the projectiondisappears in the mature stage. The mature spermatozoon of T. implicatus is a filiform cell that is pronouncedly elongated and has a bi-layered acrosome, a nucleus with two lateral longitudinal grooves, a neck region with the centriole adjunct, a flagellum with a simple 9 + 2 axoneme, two extra-axonemal accessory structures, two accessory bodies, and two mitochondrial derivatives of unequal size, and a prominent glycocalyx. The basic structure of spermatozoa of T. implicatus is similar to that of other Mecoptera studied. However, this species shows characteristics unique in Bittacidae, such as the reniform appearance of the centriole adjunct, two triangular accessory bodies with granular materials, and two asymmetric mitochondrial derivatives with a circular profile in cross-section. The potential utilization of the sperm ultrastructure for understanding the phylogeny of Bittacidae is briefly discussed.

The histomorphological structure of the male reproductive system of maize leaf weevil Tanymecus dilaticollis Gyllenhal, 1834 (Coleoptera: Curculionidae).

The histomorphology of the reproductive system and the germ cells has been useful to establish phylogenetic relationships in many insects. However, these elements remain little known in the Curculionidae. In this study, histomorphological structure of the male reproductive system of Tanymecus dilaticollis, which is economically important, is described, illustrated using stereomicroscopy, light microscopy, and scanning electron microscopy techniques, and discussed in relation to other Coleoptera species. Results showed that distinctive features of the male reproductive system of T. dilaticollis consist of a pair of yellowish testes, a pair of seminal vesicles, a pair of vasa deferentia, an ejaculatory duct, accessory glands, prostate glands, and aedeagus. Each testis is subdivided into two testicular follicles, enclosed by a peritoneal sheath. Each follicle of the mature testes is full sperm cysts with germ cells at various stages development of spermatogenesis. The testes have four types of germ cells (spermatogonia, spermatocytes, spermatids, and spermatozoa). They are occupied by the growth zone containing spermatogonia and spermatocytes, the maturation zone containing spermatids, while differentiation zone containing spermatozoa. There is a seminal vesicle at the center of each testis. Most mature sperms are stored in the seminal vesicle. Each testis is attached to the vas deferens by a stalk-like seminal vesicle. In the distal part, vasa deferentia fuse with the ejaculatory duct. It is linked to the aedeagus. The provided results will contribute to the understanding of the reproductive cell biology of Curculionidae.

Comparative ultrastructure of the spermatogenesis of three species of Poecilosclerida (Porifera, Demospongiae)

The spermatogenesis of Porifera is still relatively poorly understood. In the past, it was accepted that all species presented a primitive-type spermatozoon, lacking special structures and acrosome. Nonetheless, a very peculiar spermatogenesis resulting in a sophisticated V-shaped spermatozoon with an acrosome was found in Poecilosclerida. This finding called into question the diversity and evolution of sperm cells in Poecilosclerida and in Porifera, as a whole. Is this sophisticated spermatozoon widespread in the group? We investigated here the ultrastructure of the spermatogenesis of three different species of Poecilosclerida (Demospongiae): Iophon proximum, I. piceum, and Tedania ignis. In all three species, spermatogenesis was synchronized within the spermatic cysts. Iophon proximum and T. ignis presented elongated sperm cells, but in I. piceum, their shape was oblong. A structure resembling an acrosome was only found in T. ignis. All three species presented modified spermatozoa, as in the majority of poecilosclerids investigated so far. Therefore, we are proposing that the elongated shape (modified type) of spermatozoon is the ancestral state based in the current phylogeny of Poecilosclerida and that the V-shaped sperm is only found in Crambeidae.

Male reproductive system and spermatogenesis of Limodromus assimilis (Paykull 1790).

Based on advanced light and electron microscopy, we describe the male reproductive system and sperm development of Limodromus assimilis. The genital tract consists of pairs of uni-follicular testes, spermatic ducts with diverticula regions, seminal vesicles, accessory glands, an unpaired ejaculatory duct and an aedeagus containing an internal sac equipped with sclerotic scales. Based on their morphology, we draw conclusions about their functions. After spermatogenesis within the follicle, the spermatozoa become released from the sperm cysts. The single spermatozoa move into the diverticula of the vasa deferentia I. Here, they become attached to central rods (spermatostyles), forming secondary conjugates (spermiozeugmata). The coordinated flagella movement of the conjugates possibly improves sperm velocity. Using super-resolution microscopy, we identified highly condensed reticulate chromatin in the lancet-shaped spermatozoa heads and the mitochondrial derivates of the flagella, likely formed by genomic and mitochondrial DNA, respectively. The results show, for the first time, sperm bundle formation in a Platynini species mainly corresponding to that found in Pterostichini species.

X chromosome drive in a widespread Palearctic woodland fly, Drosophila testacea.

Selfish genes that bias their own transmission during meiosis can spread rapidly in populations, even if they contribute negatively to the fitness of their host. Driving X chromosomes provide a clear example of this type of selfish propagation. These chromosomes have important evolutionary and ecological consequences, and can be found in a broad range of taxa including plants, mammals and insects. Here, we report a new case of X chromosome drive (X drive) in a widespread woodland fly, Drosophila testacea. We show that males carrying the driving X (SR males) sire 80-100% female offspring and possess a diagnostic X chromosome haplotype that is perfectly associated with the sex ratio distortion phenotype. We find that the majority of sons produced by SR males are sterile and appear to lack a Y chromosome, suggesting that meiotic defects involving the Y chromosome may underlie X drive in this species. Abnormalities in sperm cysts of SR males reflect that some spermatids are failing to develop properly, confirming that drive is acting during gametogenesis. By screening wild-caught flies using progeny sex ratios and a diagnostic marker, we demonstrate that the driving X is present in wild populations at a frequency of ~10% and that suppressors of drive are segregating in the same population. The testacea species group appears to be a hot spot for X drive, and D.testacea is a promising model to compare driving X chromosomes in closely related species, some of which may even be younger than the chromosomes themselves.

Effects of endocrine disruptors on reproduction in viviparous teleosts with intraluminal gestation

Many water systems worldwide are affected by pollutants, including potential endocrine disruptors (EDs). Most studies on the effects of EDs on fish reproduction have focused on oviparous species. However, some important groups of fishes are not oviparous and there is scarce information about how EDs affect species with alternative reproductive modes. Goodeinae is a viviparous matrotrophic subfamily with intraluminal gestation (IG), where transfer of nutrients occurs and embryos develop inside the ovarian cavity. Goodeinae is endemic to the Mexican Central Plateau, an area affected by potential EDs, including 2,4-dichlorophenoxyacetic acid (2,4-D). This review synthesizes the available information about EDs in viviparous teleosts with IG and performs a case study on the effects of 2,4-D on gonadal structure of two Goodeinae species. We hypothesized that individuals exposed to 2,4-D might show altered gonadal structure. The available information included effects on gene expression, sexual differentiation, gametogenesis, secondary sexual characteristics, and sexual behavior. Knowledge gaps persisted on the effects of EDs on viviparous teleosts with IG. Holistic approaches are needed to understand the mechanisms underlying endocrine disruption effects. Field studies are needed to evaluate the consequences of EDs on wild populations. The case study revealed histological alterations in oocytes, spermatogonia, and sperm cysts in fishes exposed to 2,4-D. Ultrastructurally, gonads exhibited alterations in oocyte mitochondrial and nuclear membranes, and in spermatid mitochondria. The observed changes could be related to 2,4-D exposure, which may affect species reproduction in their natural environment. Matrotrophic viviparous teleosts with IG may serve as models to explore endocrine disruption.

Gonadal Morphology and Gametogenesis in Japanese Red Coral Corallium japonicum (Octocorallia: Alcyonacea) Collected off Cape Ashizuri, Japan.

Colonies of the Japanese red coral Corallium japonicum Kishinouye, 1903 collected off Cape Ashizuri, Japan were gonochoric and produced gonads in siphonozooids annually, mainly during the spring season. Polyp anatomy, gonadal morphology and gametogenesis in this species were revealed by light and electron microscopy. A siphonozooid had a pharynx with a prominent siphonoglyph and eight mesenteries: two sulcal, two asulcal, and four lateral. A rudimentary retractor was found on one side of each mesoglea of these mesenteries. The retractor arrangement in the siphonozooid was reverse of what was described in the autozooids of octocorals. Gonads initiated as small protrusions on the mesenteries, except in the asulcal ones, and even at an incipient stage they were covered with a sac-shaped thin layer of mesoglea, which was continuous with the mesoglea of mesenteries. Gastrodermis enveloped the complete outer surface of the thin layer of mesoglea throughout gametogenesis in both oocytes and sperm cysts. Oocytes produced many microvilli on their cortical surfaces beneath the thin layer of mesoglea concomitantly with the accumulation of lipid globules in the cells, whereas in sperm cysts spermatocytes and spermatids increased in number without microvilli production, followed by synchronous spermiogenesis involving remarkable changes in the shape and position of organelles. Based on the comparison of patterns in gonadal development between octocorals including C. japonicum, hexacorals and scyphozoans, octocoral and stauromedusa species may be characterized by the fact that gametogenesis never occurs in the matrix of mesoglea, but rather exclusively within the thin sac of mesoglea surrounded by gastrodermis.

Seasonality and lunar periodicity in the sexual reproduction of the coral-killing sponge, Terpios hoshinota

Sexual reproduction of the cyanobacteriosponge, Terpios hoshinota, was studied at Lyudao (Green Island), Taiwan, from 2011 to 2013 through histological examinations, electron microscopy, and in situ observations of larval release. Histological examinations identified five reproductive structures: oocytes, sperm cysts, cell masses, early-stage embryos, and mature embryos. These reproductive structures were often observed in the same specimens, indicating that T. hoshinota is a hermaphroditic brooder. No cyanobacteria were seen in the gametes, and transmission of symbiotic cyanobacteria from parental tissues to larvae likely occurred during embryogenesis. The cell mass, a loose aggregate of numerous symbiotic cyanobacteria and maternal sponge cells, appeared to be eventually incorporated and constitutes the inner part of pre-hatching larvae, suggesting that the larval type is pseudoblastula instead of parenchymella as previously suggested. A clear lunar periodicity was seen in the reproductive cycle; larvae were released mostly around the full moon and occasionally around the new moon. Reproductive activity declined during months with low temperatures (January–April). The larvae were characterized by negative buoyancy and limited mobility, suggesting a larval dispersal distance on a scale of meters under calm weather. However, long-distance dispersal of larvae could still be possible through occasional strong currents during bad weather, such as typhoons, if the larvae survived during the dispersal period by accessing extra energy from the symbiotic cyanobacteria through their photosynthates and/or consuming the cyanobacteria as a source of nutrients. This study showed that T. hoshinota has high fecundity, with a monthly release of numerous larvae over a long reproductive season. This high fecundity, along with local larval dispersal and rapid post-settlement growth, enables rapid population expansion of T. hoshinota.

FERTILIDAD Y FECUNDIDAD DE MONTASTRAEA ANNULARIS EN UN ARRECIFE DEGRADADO

This study determined the gametogenic cycle, fecundity and fertility of Montastraea annularis, in the Isla Grande coral reef, Archipelago of Nuestra Señora del Rosario, one of the most degraded reefs in the Colombian Caribbean. The surveyed population is currently characterized by medium size colonies (ca. 3379 cm2), with 27 % of the ramets showing partial mortality and 10 % with total mortality. Colonies present high number of small sized ramets formed by !ssion (76 %, smaller than 50 cm2). Based on the above mentioned population structure characteristics, the aim of this research was to explain the low recruitment rate reported for this reef through the reproductive response of a population dominated by small ramets. Between September 2003-2004, tissue fragments were collected and histological slides were made to detail the development of oocytes and spermaries and to estimate fecundity. Additionally during September of 2003 and 2004, in situ spawned eggs were collected to quantify fecundity. Results showed that oogenesis occurred between May and September and the spermatogenesis between July and September. Fertility was low (35 % and 40 %, in situ and histology, respectively) as well as fecundity (20 and 11 eggs/cm2/year-1, in situ and histology, respectively). Of the 33 % of ramets that showed spermaries, only 3 % of the mesenteries presented male gametes and in these, the presence of sperm cysts was also scarce (4 espermaries/gonad). Although the size of the ramets did not show a statistical relationship with fertility or fecundity, ramets between 50 and 100 cm2 were found more fecund than smaller (<50 cm2) or larger ramets (>200 cm2). The poor reproductive effort found can, in part, explain the low number of small colonies in the studied population, which in turn is expected in degraded sites and in populations with high !ssion rates. The results suggest that the viability of the population of M. annularis at Isla Grande is de!ned by the low number of fertile ramets and the low fecundity, but especially by low production of male gametes.

Sexual reproduction of the potentially cultivable sponge Mycale phyllophila (Porifera, Demospongiae)

Sponges of the Mycale genus are an important source of several bioactive metabolites. The raw materials for studies on this genus mainly come from the wild populations. However, the scarce biomass of sponges in the wild has become an obstacle to the better investigation of the active substances. To establish aquaculture methods based on the sexual reproduction of the demosponge Mycale phyllophila and solve the sponge shortage problems, the sexual reproductive cycle of this species was studied. Our investigation is the first to report the sexual reproduction of the Mycale species in the coastal waters of China. We collected the sponge specimens from Dongshan Bay (Fujian, China) monthly from June 2012 to January 2014. Small samples of approximately 8 cm3 in volume were cut from 15 sponges (10 tagged individuals and five random individuals) with surgical scissors for histological analysis. The results indicated that M. phyllophila is a hermaphroditic and viviparous species. The primary oocytes measured 30–50 μm in diameter, while mature oocytes reached 300–400 µm by engulfing nearby nurse cells. Spermatic cysts containing asynchronous cells were found throughout the mesohyl, especially adjacent to the oscula. Macromeres in the middle and micromeres in the periphery were observed as the cleavage progressed. The reproductive activity of M. phyllophila lasted for 5–6 months and peaked when the average water temperature was above 25°C. This suggests that water temperature is an important environmental factor influencing the sexual reproduction cycle.

Asynchronous reproduction and multi-spawning in the coral-excavating sponge Cliona delitrix

Cliona delitrix is one of the most abundant and destructive coral-excavating sponges on Caribbean reefs. However, basic aspects of its reproductive biology, which largely determine the species propagation potential, remain unknown. A 2-year study (October 2009 to September 2011) was conducted to determine the reproductive cycle and gametogenesis of a C. delitrix population located in a shallow reef in Florida, USA. Mesohyl tissue collected from randomly chosen and tagged sponge individuals was sampled one to several times a month, and analysed by light and transmission electron microscopy (TEM). Cliona delitrix is oviparous and gonochoric, except for a few simultaneous hermaphroditic individuals. The C. delitrix reproductive cycle in Florida is from April to December, and is triggered by an increase in seawater temperature to 25°C. Oogenesis and spermatogenesis were asynchronous among individuals; with different cohorts of oocytes co-occurring in females, and spermatic cysts in males. Granulose cells acted as nurse cells, contributing to the growth and maturation of both female and male gametes. Spawning of gametes was not always synchronized with full moon phase. Unlike most other oviparous sponges, the reproductive cycle of C. delitrix is versatile and includes multiple spawning events during the summer of each year. This characteristic maximizes sponge propagation on coral reefs during the warmer months of the year, particularly when thermal stress induces coral mortality. This aspect, combined with its success on polluted areas, make C. delitrix a suitable bioindicator of coral reef health.

Male reproductive maturity and diapause termination in the leaf beetle Gastrophysa atrocyanea

AbstractMale reproductive potential and growth of testes are studied in the leaf beetle Gastrophysa atrocyanea Motschulsky (Coleoptera: Chrysomelidae) that is exposed to mild temperatures after imaginal ecdysis. Continuous administration of the Juvenile Hormone (JH) in artificial diet is highly effective with respect to stimulating testes growth and mating behaviour. Female reproductive diapause can be induced under standard rearing conditions, although optimum reproductive maturity of males is achieved at 15 °C. Treatment of males with a JH analogue accelerates testes development up to the stage of spermiogenesis (the bundling of spermatozoa) but does not promote the formation of cysts with mature sperm. Treatment with 20‐hydroxyecdysone has no influence on diapause termination and testes function. These results suggest that male reproductive maturation in G. atrocyanea is independent of JH, and moderate temperatures may induce an unknown factor that is responsible for the maturation of sperm cysts.