Feminization, altered gonadal development, and liver damage in least killifish (Heterandria formosa) exposed to sublethal concentrations of 17α-ethinylestradiol.

The widespread use of the synthetic estrogen 17 α-ethinylestradiol (EE2) has resulted in elevated levels in aquatic environments, where it is known to act as an endocrine disrupting chemical affecting fish and other aquatic organisms. Examining changes in the structure of the fish' gonads and liver has proven to be an effective approach for assessing these impacts. While changes have been reported for various fish species, it is not clear whether impacts are equally severe in live-bearing fishes. The present study looked at gonadal and liver development in EE2-exposed least killifish (Heterandria formosa), a live-bearing Poeciliid. Exposures to 0, 5, or 25 ng/L EE2 began within six days of birth and continued until fish became sexually mature 12-23 weeks later. Exposure to 5 ng/L EE2 resulted in severe intersex in fish with external male characteristics, a slowdown of spermatogenesis in these intersex fish and a slowdown of oogenesis in the female fish. Moreover, these fish had a variety of liver injuries. Fish exposed to 25 ng/L EE2 exhibited intersex but at a lower frequency than occurred at 5 ng/L. In contrast, liver damage and slowdown of both oogenesis and spermatogenesis exhibited the typical dose-dependence. These findings illustrate the importance of including histological analyses when assessing endocrine disruption in fish, demonstrate that the live-bearing mode of reproduction appears to provide limited protection from the effects of waterborne EE2, and provide further evidence that EE2 has multiple impacts on fish health and reproduction that are severe enough to potentially affect fish populations.

Larval aquatic and terrestrial mites infesting a temperate assemblage of mosquitoes.

We collected 22,769 adult female mosquitoes, representing 27 species, from light traps in Norfolk, Virginia (2006-2007) and examined them to assess infestation by larval mites. Mosquitoes were parasitized by two species of aquatic (Acari: Arrenuridae: Arrenurus) and three species of terrestrial mites (Acari: Erythraeidae). The prevalence of infestation varied from 0.55% (2006) to 0.17% (2007). The mean intensity of parasitism ranged from 3.6 mites per host (2006) to 1.8 mites per host (2007). The most common host species for aquatic mites was Culex erraticus, while the most common host for terrestrial mites was Anopheles quadrimaculatus. Relationships between biotic and abiotic factors were investigated in an attempt to provide insight into temporal, spatial, and interspecific variation in mite-mosquito interactions. Scanning electron microscopy was used to examine the mode of attachment for larval mites. While the prevalence of aquatic mite parasitism was correlated for Culex erraticus, the invasive mosquito, Aedes albopictus, was never parasitized through the duration of the study.

Crude oil toxicity to fiddler crabs (Uca longisignalis and Uca panacea) from the northern Gulf of Mexico: Impacts on bioturbation, oxidative stress, and histology of the hepatopancreas.

The intensive drilling and extraction of fossil fuels in the Gulf of Mexico result in a considerable risk of oil spills impacting its coastal ecosystems. Impacts are more likely to be far-reaching if the oil affects ecosystem engineers like fiddler crabs, whose activities modify biogeochemical processes in the sediment. The present study investigated effects of oil on the fiddler crabs Uca longisignalis and Uca panacea, which are important as ecosystem engineers and as prey for a wide variety of species. The present study used mesocosms and microcosms to investigate the effects of crude oil on fiddler crab burrowing and to assess cellular and tissue damage by the oil. Fiddler crabs were exposed for periods of 5 or 10 d to oil concentrations up to 55 mg/cm2 on the sediment surface. Their burrowing was delayed, their burrows were smaller, and they transported less sediment in the presence of oil. The hepatopancreas had elevated levels of oxidative stress and a higher abundance of blister cells, which play a role in secretory processes. Interspecific differences were observed; most effects were strongest in U. panacea, though burrowing was more strongly affected in U. longisignalis. The present study demonstrates that crude oil is likely to impact fiddler crabs and many species that depend on them for their diet or for the ecological changes that result from their burrowing. Environ Toxicol Chem 2018;37:491-500. © 2017 SETAC.

Eukaryotic Life Inhabits Rhodolith-forming Coralline Algae (Hapalidiales, Rhodophyta), Remarkable Marine Benthic Microhabitats.

Rhodoliths are benthic calcium carbonate nodules accreted by crustose coralline red algae which recently have been identified as useful indicators of biomineral changes resulting from global climate change and ocean acidification. This study highlights the discovery that the interior of rhodoliths are marine biodiversity hotspots that function as seedbanks and temporary reservoirs of previously unknown stages in the life history of ecologically important dinoflagellate and haptophyte microalgae. Whereas the studied rhodoliths originated from offshore deep bank pinnacles in the northwestern Gulf of Mexico, the present study opens the door to assess the universality of endolithic stages among bloom-forming microalgae spanning different phyla, some of public health concerns (Prorocentrum) in marine ecosystems worldwide.

Morphology and ultrastructure of the Malpighian tubules of the Chilean common tarantula (Araneae: Theraphosidae).

Relatively little is known about the morphology and ultrastructure of the Malpighian tubules of spiders (Arachnida: Araneae). Our study represents the first investigation of the Malpighian tubules of a theraphosid spider and is the only study to examine the living Malpighian tubules using confocal laser scanning microscopy. In theraphosid spiders, the Malpighian tubules originate from the stercoral pocket in the posterior portion of the opisthosoma and extend forward toward the prosoma in a dendritic pattern. There are three distinct segments (initial, main, and terminal), all dark brown in appearance. Each segment has distinctive ultrastructural features. Both the terminal and the main segment appear to be composed of at least two cell types with finger-like cytoplasmic protrusions associated with one of these types. The terminal segment, which is most proximal to the stercoral pocket, is the largest in diameter. It is composed of large, cuboidal cells containing many mitochondria and lipid inclusions. The main segment is intermediate in diameter with many mitochondria and secretory vesicles present. The initial segment is relatively thin in comparison to the other segments and is intimately associated with the digestive gland. The cells of the initial segment contain very little cytoplasm, fewer mitochondria, secretory vesicles, and prominent inclusions.

The harvestman tarsus and tarsal flexor system with notes on appendicular sensory structures in Laniatores.

The tarsal flexor system, a novel system of retinacular structures, is described for the first time based on morphological and ultrastructural examinations of several Neotropical harvestmen (Opiliones: Laniatores). The tarsal flexor system is made up of many individual pulleys that function to maintain close apposition between the tendon and internal ventral surface of the cuticle in the tarsus. Pulley cells are specialized tendinous cells that form the semi-circular, retinacular pulley system in the tarsus; these cells contain parallel arrays of microtubules that attach to cuticular fibers extending from deep within the cuticle (i.e., tonofibrillae). The tarsal flexor system is hypothesized to provide mechanical advantage for tarsal flexion and other movements of the tarsus. This system is discussed with regards to other lineages of Opiliones, especially those that exhibit prehensility of the tarsus (i.e., Eupnoi). Comparing tarsal morphology of laniatorid harvestmen to other well-studied arachnids, we review some literature that may indicate the presence of similar tarsal structures in several arachnid orders. The general internal organization of the tarsus is described, and ultrastructural data are presented for a number of tarsal structures, including sensilla chaetica and the tarsal perforated organ. Sensilla chaetica possess an internal lumen with dendritic processes in the center and exhibit micropores at the distal tip. With respect to the tarsal perforated organ, we found no ultrastructural evidence for a sensory or secretory function, and we argue that this structure is the result of a large pulley attachment site on the internal surface of the cuticle. A small, previously undocumented muscle located in the basitarsus is also reported.

Ultrastructure of the sexually dimorphic tarsal glands and tegumental glands in gonyleptoid harvestmen (Opiliones, Laniatores).

In at least four closely related families of the diverse harvestmen lineage Gonyleptoidea, males may possess sexually dimorphic tarsal glands in the swollen tarsomeres of the basitarsus and/or metatarsus of leg I. The first histological and ultrastructural examination of the sexually dimorphic tarsal glands in leg I focused only on Manaosbiidae. In this study, we examine the morphology and ultrastructure of the sexually dimorphic glands, and their associated glandular openings, found in the basitarsus and/or metatarsus of leg I of males representing Cosmetidae, Gonyleptidae, and Cranaidae (glandular openings only). In cosmetids and gonyleptids, the tarsal glands are made up of 20­60 glandular units that form distinct groups within the prolateral and retrolateral half of the tarsomere. Each glandular unit consists of a pair of terminal secretory cells, an intercalary cell wrapped around the receiving canal, and a canal cell tightly wrapped around the length of the conducting canal. Cosmetidae, Gonyleptidae, and Cranaidae exhibit remarkably similar tarsal glands and gland openings although the location of the glands in the leg differs slightly among them. Males of these three families exhibit markedly different glands and glandular openings compared to males of the family Manaosbiidae. The sexually dimorphic tarsal glands may provide an important morphological character for determining phylogenetic relationships among gonyleptoid families. Finally, we provide morphological and ultrastructural data for the common tegumental glands. These data indicate that the sexually dimorphic tarsal glands are strikingly similar to, and may possibly be derived from, the tegumental glands.

Ultrastructure of the sexually dimorphic basitarsal glands of leg I in manaosbiid harvestmen (Opiliones, Laniatores).

Chemical communication is an important aspect of arthropod biology especially for those arthropods with limited abilities to detect visual and acoustic signals. Sexually dimorphic glands are often associated with the production of pheromones, which play a role in reproductive processes. In the family Manaosbiidae (Opiliones: Laniatores), males exhibit an enlarged, swollen, often fused, and spindle-like basitarsus on leg I. In this study, we provide a novel description of the morphology and ultrastructure of the glandular structures found in the proximal swollen tarsomeres of the male manaosbiid Rhopalocranaus albilineatus Roewer, 1932 and compare the external leg I morphology with that of two other manaosbiid harvestmen (Barrona williamsi Goodnight and Goodnight, 1942 and Cranellus montgomeryi Goodnight and Goodnight, 1947). The two proximal tarsomeres of the male R. albilineatus leg I contain two large, paired, acinar glands consisting of many glandular cells. Cells empty their secretory products into a large, branched epicuticular duct, which exits the leg via a pore on the ventral region. Thus, a total of four glandular structures are present within the two swollen tarsomeres and each possesses a conducting canal and pore. Finally, we discuss possible roles of these basitarsal glands in manaosbiid reproductive biology based on the present understanding of sexually dimorphic glands in other terrestrial arthropods (i.e., insects and spiders).

Morphological changes during postembryonic development in two species of neotropical harvestmen (Opiliones, Laniatores, Cranaidae).

Morphological changes during postembryonic development in the Cranaidae are described on the basis of the examination of an incomplete series of larvae, nymphs, and adults of Phareicranaus calcariferus and Santinezia serratotibialis. The life histories of these species are hypothesized to consist of six nymphal stages, featuring the appearance of secondary male sexual characteristics in the antepenultimate nymph (N5). Color and body shape change dramatically during development. Growth rates for nymphs based upon leg measurements were similar for both species. In S. serratotibialis, the greatest increase in leg size occurred from larva to 1st nymph. The tarsomeres of legs I-IV varied by 1-2 segments per leg for each nymph stage, with the number of tarsal segments increased by 1-2 segments at each stage. Adults had nearly twice as many tarsomeres on leg II than other legs. Ontogenetic changes were observed in the armature of the proximal cheliceral segment, ocularium, pedipalp, opisthosoma, distitarsus III and IV, and leg IV. Morphological changes in postembryonic development in cranaid harvestmen are similar to those reported for other Laniatores.

Ultrastructure and functional morphology of glandular setae and distal claws of cephalic appendages of Speleonectes tanumekes (Crustacea: Remipedia).

Terminal pores on crustacean setae are commonly associated with chemoreception. In this study we present an exception to that association with the description of glandular setae on maxillulary and maxillary endites of the remipede Speleonectes tanumekes. This introduces a function associated with crustacean setae beyond the general functions currently assigned to crustacean setae: sensory functions, mechanical functions, or a combination of these two. Even though the functions of the secretory products are unclear, we suggest means by which these may contribute to feeding behaviors. In addition, we describe glandular features of maxillary and maxillipedal distal claws of the same remipede species. Glandular setae and distal claws appear to share several morphological homologies.

Excretion in the house cricket Acheta domesticus: Effects of diuretics on the structure of the mid-tubule.

Most structural studies of insect Malpighian tubules focus on freshly dissected tissue, which is in fact stimulated by diuretic factors. In this study, we examine tubules from the house cricket Acheta domesticus in four discrete secretory states: control (freshly dissected); unstimulated (held in vitro for 90 min prior to fixation); corpus cardiacum-stimulated (held in vitro for 60 min, then stimulated with corpus cardiacum homogenates for 30 min prior to fixation); and cAMP-stimulated (held in vitro for 60 min, then stimulated with dibutyryl cAMP for 30 min prior to fixation). In unstimulated tubules, we see a reduction in vacuolization and a near-complete collapse of the basolateral infolds. Stimulated tubules show several major structural shifts: mitochondria are darkly stained with well-defined cristae, there is extensive vacuolization of the tissue and expansion of the basolateral spaces, and the CaPO4 spherites appear to be ejected into the lumen. cAMP-stimulated tubules showed the most pronounced structural changes, including the presence of a newly reported ultrastructural feature for A. domesticus Malpighian tubules, referred to here as paracrystalline arrays, which appear as stacks of membrane localized in the perinuclear region. © 1996 Wiley-Liss, Inc.

The cuticular scales of Lynx spiders (Araneae, Oxyopidae).

An examination of the cuticular scales of the lynx spiders Oxyopes aglossus, O. salticus, and Peucetia viridans using scanning electron microscopy revealed that scales in these spiders are morphologically distinct, yet similar to the scales of the jumping spiders Eris militaris and Hentzia mitrata. Like the cuticular scales of jumping spiders, the cuticular scales of lynx spiders exhibit morphological differentiation in regard to location of occurrence on the body, with scales near the eyes tending to have more numerous and larger spines on the superior surface than scales on other regions of the prosoma and opisthosoma. The functional significance of this differentiation in scale morphology is unknown. Sexual dimorphism and ontogenetic variation in scale morphology and color were observed in the genus Oxyopes,but not in Peucetia. In addition, the scales of P. viridans were distinguishable from the scales of Oxyopes spp. on the basis of the number of apical spines (1 in P. viridans instead of 3-7 in Oxyopesspp.) and on the presence of spines on the inferior surface (many in P. viridans and none in Oxyopesspp.). J. Morphol. 236:223-231, 1998. © 1998 Wiley-Liss, Inc.

Ultrastructure of the cuticular scales of lynx spiders (Araneae, Oxyopidae) and jumping spiders (Araneae, Salticidae).

The cuticular scales of spiders are flattened setae that may occur in a diverse array of colors and shapes on the dorsal and lateral surfaces of the prosoma, opisthosoma, and walking legs. In this study, we used transmission electron microscopy (of both sections and wholemounts) and scanning electron microscopy (in concert with paraffin carving) to examine the internal anatomy and ultrastructure of the cuticular scales of several species of lynx spiders (Oxyopidae) and jumping spiders (Salticidae). We also examined iridescent and noniridescent pigmented scales for species in both families. In addition to discovering intra- and interspecific and sexual differences in scale ultrastructure, the results of our research also indicate that the ultrastructure of the scales of these spiders varies directly with coloration. For iridescent scales, we found a general absence of trabeculae, a lack of pigment granules, and an almost complete fusion of the the upper and lower laminae. For noniridescent scales, we observed granules, well-formed trabeculae, and a complex internal structure consisting of internal elements within the lumen of the scale. Our examination of the scales of these spiders represents the first complete description of the ultrastructure of the cuticular scales of any species of spider. J. Morphol. 240:77-92, 1999. © 1999 Wiley-Liss, Inc.

Fluid-phase endocytosis does not contribute to rapid fluid secretion in the malpighian tubules of the house cricket, Acheta domesticus.

When the Malpighian tubules (Mt) of the house cricket (Acheta domesticus) are treated with dibutyryl adenosine 3', 5'-cyclic monophosphate (db-cAMP; 1 mM), which causes a doubling in secretion rate, more than 50% of the cell volume is occupied by vesicles within 420 sec of exposure. In view of the fact that the increase in vesiculation occurs concomitantly with stimulated fluid transport, we set out to determine whether the vesicles are formed as a result of fluid-phase endocytosis (pinocytosis) and subsequently used to transport fluid to the lumen as one means of increasing transport rate. We used fluorescent fluid-phase markers (Lucifer Yellow Carbohydrazide [LYCH] and Alexa 488 hydrazide) and an electron dense marker (cationized ferritin) to elucidate the degree of endocytosis that occurred with db-cAMP stimulation. We found that, although some fluid is taken into the cells of the mid-tubule via endocytosis, it does not coincide with the level of vacuolation present in stimulated tubules. The amount of LYCH transported into the primary urine by the db-cAMP-stimulated Mt decreased by 40% as compared to the unstimulated transport, and the rate of transport of LYCH was only 30% of the unstimulated tubules. In summary, our findings do not support the theory that the majority of the vesicles or vacuoles comprise intracellular, endocytotic compartments formed via a basolateral endocytotic pathway. We also found no evidence to support the functioning of vesicles or vacuoles as transcellular "shuttling" mechanisms to move fluid from the basal region to the apical membrane and into the lumen.