Body musculature of Beauchampiella eudactylota (Gosse, 1886) (Rotifera: Euchlanidae) with additional new data on its trophi and overall morphology

This study presents the results of confocal laser scanning microscopy and fluorescence‐labelled phalloidin used to visualize the system of body musculature in Beauchampiella eudactylota. Moreover, the poorly known trophi of B. eudactylota are described based on scanning electron microscopy. In total, four paired longitudinal muscles (musculi longitudinales I–IV) and three circular muscles (musculi circulares I–III) were identified. Among these are the musculus longitudinalis ventralis, the musculus longitudinalis dorsalis and the musculus circumpedalis as documented in previous studies for other rotifer species. Compared to other species, B. eudactylota is characterized by the low number of lateral longitudinal muscles and the absence of some longitudinal muscles (musculi longitudinales capitum) and circular muscles (corona sphincter, musculus pars coronalis). Moreover, scanning electron microscopic data on the trophi of B. eudactylota reveal a number of striking similarities to the trophi in some species of Epiphanidae. This suggests that either (1) these similarities represent plesiomorphic characters present both in Epiphanidae and B. eudactylota or (2) they are synapomorphic features of B. eudactylota and some species of Epiphanidae, which would question the monophyly of Euchlanidae.     

The musculature of Squatinella rostrum (Milne, 1886) (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology

Wilts, E.F., Wulfken, D., Ahlrichs, W.H. and Martínez Arbizu, P. 2012. The musculature of Squatinella rostrum (Milne, 1886) (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology.—Acta Zoologica (Stockholm) 93 : 14–27. The monogonont rotifer Squatinella rostrum was investigated with light, scanning electron and confocal laser scanning microscopy to reveal new morphological data on its inner and outer anatomy. In total, the visualized somatic musculature displays five paired longitudinal muscles (musculi longitudinales I–V) and nine circular muscles (musculi circulares I–IX). Compared to other species, S. rostrum is characterized by the absence of several longitudinal and circular muscles (e.g. musculus longitudinalis capitis, corona sphincter and pars coronalis). A reconstruction of the mastax musculature revealed a total number of seven paired and two unpaired mastax muscles. Possibly homologous somatic and mastax muscles in other, thus far investigated rotifers are discussed. Moreover, we provide a phylogenetic evaluation of the revealed morphological characters and suggest possible autapomorphic characters supporting Squatinella and Lepadellidae. Finally, we refer to some striking similarities in the morphology, ecology and way of movement of Squatinella and Bryceella that may indicate a closer relationship of both taxa.     

The neuromuscular system of the cyclostome bryozoan Crisia eburnea (Linnaeus, 1758)

The cyclostome bryozoans constitute an old and divergent group of bryozoans, whose muscle and nervous systems are poorly known. The entire neuromuscular system of the cyclostome Crisia eburnea is here mapped with phalloidin, DAPI and antibodies directed against acetylated α-tubulin and serotonin. Innervation of most muscles as well as the ganglion of C. eburnea is described, and several new details are reported, for example, on the additional and branched ectodermal muscles of the cystid, the presence of subtentacular muscles, the retractor muscles being distinctly striated and the presence of an additional pair of lateroabfrontal nerves in the proximal part of the tentacles. The serotonin-like immunoreactivity in the nervous system of C. eburnea shares many features with those of the other bryozoans studied so far, which probably reflects a common ancestry of the neural architecture. However, the nervous system shows somewhat less complexity compared to that of the sister clade, Eurystomata, and contains fewer cells and nerves compared to the cyclostome Cinctipora which has much larger zooids and more than eight tentacles. No interzooidal neural connections were found in C. eburnea, which is in agreement with the individual response of the zooids.     

The metareticulate pollen morphology of Alternanthera Forssk. (Gomphrenoideae,Amaranthaceae) and its taxonomic implications

Alternanthera (Amaranthaceae) is a diverse genus largely restricted to the American Tropics that belongs to the alternantheroid clade containing C₄ and C₃–C₄ intermediate species. This research focuses on the study of pollen characters by studying 13 species, representatives of the two major clades and subclades of Alternanthera. General palynological comparisons were conducted with light microscopy (LM), scanning electron microscopy (SEM) and with confocal laser scanning microscopy (CLSM) for exine ultrastructure. Twenty-five characters were measured and described for Alternanthera and among these, 14 pollen characters were used to discriminate pollen groups using cluster analysis and canonical analysis of principal coordinates (CAP). Pollen form and ornamentation, pores number, spines length, number of ektexinous bodies and nanospines on the ektexinous bodies on pore membranes, arrangement of nanopores and spines on structural elements, and metareticula form were taxonomically important and therefore used to construct the first palynological key to the alternantheroid clade species. Our study indicates that the seemingly subtle morphological variation of pollen is useful for recognising three main pollen types within Alternanthera. The much needed palynological terminology for describing the mesoporium in the metareticulate pollen of Amaranthaceae is provided.     

The quest for four-dimensional imaging in plant cell biology: it's just a matter of time

BACKGROUND: Analysis of plant cell dynamics over time, or four-dimensional imaging (4-DI), represents a major goal of plant science. The ability to resolve structures in the third dimension within the cell or tissue during developmental events or in response to environmental or experimental stresses (i.e. 4-DI) is critical to our understanding of gene expression, post-expression modulations of macromolecules and sub-cellular system interactions. SCOPE: Microscopy-based technologies have been profoundly integral to this type of investigation, and new and refined microscopy technologies now allow for the visualization of cell dynamics with unprecedented resolution, contrast and experimental versatility. However, certain realities of light and electron microscopy, choice of specimen and specimen preparation techniques limit the scope of readily attaining 4-DI. Today, the plant microscopist must use a combinatorial strategy whereby multiple microscopy-based investigations are used. Modern fluorescence, confocal laser scanning, transmission electron and scanning electron microscopy provide effective conduits for synthesizing data detailing live cell dynamics and highly resolved snapshots of specific cell structures that will ultimately lead to 4-DI. This review provides a synopsis of such technologies available.     

Characteristics of the Infection of Tilletia laevis Kühn (syn. Tilletia foetida (Wallr.) Liro.) in Compatible Wheat

Tilletia laevis Kühn (syn. Tilletia foetida (Wallr.) Liro.) causes wheat common bunt, which is one of the most devastating plant diseases in the world. Common bunt can result in a reduction of 80% or even a total loss of wheat production. In this study, the characteristics of T. laevis infection in compatible wheat plants were defined based on the combination of scanning electron microscopy, transmission electron microscopy and laser scanning confocal microscopy. We found T. laevis could lead to the abnormal growth of wheat tissues and cells, such as leakage of chloroplasts, deformities, disordered arrangements of mesophyll cells and also thickening of the cell wall of mesophyll cells in leaf tissue. What’s more, T. laevis teliospores were found in the roots, stems, flag leaves, and glumes of infected wheat plants instead of just in the ovaries, as previously reported. The abnormal characteristics caused by T. laevis may be used for early detection of this pathogen instead of molecular markers in addition to providing theoretical insights into T. laevis and wheat interactions for breeding of common bunt resistance.     

Morphology and ultrastructure of spiracles in phlebotomine sandfly larvae

The morphology and ultrastructure of the larval spiracle system of three phlebotomine sandfly species, Phlebotomus perniciosus, P. perfiliewi and P. papatasi, were examined by scanning (SEM) and transmission (TEM) electron microscopy and by confocal scanning laser microscopy (CSLM). During larval development, thoracic and abdominal spiracles show considerable modifications. In fourth instar larvae, the spiracles consist of a plate with a sclerotized central portion and a peripheral circle of papillae. The latter is distinctive in the larvae of P. papatasi, which are readily distinguished from the other species. Opening clefts across the papillae communicate with an internal chamber that encircles an electrondense plug. Many cylindrical projections cross the chamber, uniting the central plug with the larval body, forming an air filter. Spiracular development in successive larval instars has both a taxonomic and adaptive value.     

The larval attachment organ of the tropical gar Atractosteus tropicus Gill, 1863 (Lepisosteiformes: Lepisosteidae)

Larval attachment organs (LAOs) are unicellular or multicellular organs that allow larvae to adhere to a substrate before yolk-sac absorption and the free-swimming stage. This study documents the LAO of tropical gar, Atractosteus tropicus, using a combination of scanning electron microscopy and light microscopy. It is shown that the LAO of A. tropicus is a super-organ surrounded by a wall and containing at its centre many smaller multicellular organ units, each comprised of attachment and support cells. Attachment cells are secretory and house large vacuoles filled with a glycoprotein. At hatching, the super-organ is well developed and occupies almost the entire anteroventral surface of the head. During subsequent development, the smaller individual units begin to regress, until at 6 days post-hatching the super-organ and its individual units are no longer visible.     

Ultrastructural studies on the epithelia of the olfactory organ of cyprinodonts (teleostei,cyprinodontoidea)

Summary The epithelia of the olfactory organ of two cyprinodontoid fish species were studied both by transmission and scanning electron microscopy. The relatively flat floor of the organ is covered by sensory and nonsensory epithelia. The latter is distributed in the form of bands or ridges separating distinct areas of sensory epithelium. Differences between the olfactory organs of the two species investigated related only to the topography and quantitative distribution of the epithelia. Their ultrastructural features are very similar. The nonsensory stratified squamous epithelium contains numerous goblet cells and surface cells provided with microridges. A hypothetical function of the microridges is discussed. The sensory epithelium consists mainly of basal, supporting, and two types of sensory cells, i.e., ciliated and microvillous receptor cells. The cilia exhibit a predominant 9+0 microtubule pattern. Both epithelia are covered by a mucus layer in which all surface structures seem to be embedded. The possible nature, origin, and movement mechanisms of the mucus are discussed.This work was supported by the Deutsche ForschungsgemeinschaftDedicated to Prof. Dr. med. W. Bargmann on the occasion of his 70th birthday     

Equine zona protein synthesis and ZP structure during folliculogenesis, oocyte maturation, and embryogenesis

In the equine, the zona pellucida (ZP) is the major barrier to successful in vitro fertilization. Therefore the aim of our studies was to analyze species-specific features of the equine ZP in regard to structure and glycoprotein ZPB and ZPC expression sites during oocyte development and embryogenesis. The equine ZP revealed high immunological cross-reactivity to porcine ZPB and ZPC. In the ovary, the distribution of ZPB and ZPC was co-localized and correlated with the developmental stage of the follicle. ZPB and ZPC expression started in the oocyte of the late primordial and primary follicle. In the secondary follicle, both the oocyte and the cumulus cells contributed to ZPB and ZPC synthesis. After in vivo maturation the oocyte stopped ZPB and ZPC production whereas the cumulus cells continued synthesis. Contrary, in vitro matured (IVM) cumulus-oocyte-complexes (COCs) revealed a reverse expression pattern. This was correlated to alterations in the distribution, number, and size of pores in the ZP. In the zona, N-acetylglucosamine residues were co-localized with ZPC. The acellular glycoprotein capsule surrounding early equine embryos was negative for ZPB and ZPC. Our results imply that in the horse ZPB and ZPC glycoprotein expression is differentially regulated during folliculogenesis, oocyte maturation, and embryogenesis. Contrary to the bovine and porcine, zona protein synthesis during in vivo maturation is completely overtaken by the cumulus cells implying that in the horse these cells are crucial for zona integrity. During IVM, the cumulus cells lose their ability to synthesize glycoproteins leading to alterations in the zona structure.     

Muscle fibers in the central nervous system of nemerteans: Spatial organization and functional role

The system of muscle fibers associated with the brain and lateral nerve cords is present in all major groups of enoplan nemerteans. Unfortunately, very little is known about the functional role and spatial arrangement of these muscles of the central nervous system. This article examines the architecture of the musculature of the central nervous system in two species of monostiliferous nemerteans (Emplectonema gracile and Tetrastemma cf. candidum) using phalloidin staining and confocal microscopy. The article also briefly discusses the body‐wall musculature and the muscles of the cephalic region. In both species, the lateral nerve cords possess two pairs of cardinal muscles that run the length of the nerve cords and pass through the ventral cerebral ganglia. A system of peripheral muscles forms a meshwork around the lateral nerve cords in E. gracile. The actin‐rich processes that ramify within the nerve cords in E. gracile (transverse fibers) might represent a separate population of glia‐like cells or sarcoplasmic projections of the peripheral muscles of the central nervous system. The lateral nerve cords in T. cf. candidum lack peripheral muscles but have muscles similar in their position and orientation to the transverse fibers. The musculature of the central nervous system is hypothesized to function as a support system for the lateral nerve cords and brain, preventing rupturing and herniation of the nervous tissue during locomotion. The occurrence of muscles of the central nervous system in nemerteans and other groups and their possible relevance in taxonomy are discussed. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Functional morphology of amplexus (clasping) in spinicaudatan clam shrimps (Crustacea,Branchiopoda) and its evolution in bivalved branchiopods: A video‐based analysis

Male clam shrimps (Crustacea: Branchiopoda: Laevicaudata, Spinicaudata, and Cyclestherida) have their first one or two trunk limb pairs modified as “claspers,” which are used to hold the female during mating and mate guarding. Clasper morphology has traditionally been important for clam shrimp taxonomy and classification, but little is known about how the males actually use the claspers during amplexus (clasping). Homologies of the various clasper parts (“movable finger,” “large palp,” “palm,” “gripping area,” and “small palp”) have long been discussed between the three clam shrimp taxa, and studies have shown that only some structures are homologous while others are convergent (“partial homology”). We studied the clasper functionality in four spinicaudatan species using video recordings and scanning electron microscopy, and compared our results with other clam shrimp groups. General mating behavior and carapace morphology was also studied. Generally, spinicaudatan and laevicaudatan claspers function similarly despite some parts being nonhomologous. We mapped clasper morphology and functionality aspects on a branchiopod phylogeny. We suggest that the claspers of the three groups were adapted from an original, simpler clasper, each for a “stronger” grip on the female's carapace margin: 1) Spinicaudata have two clasper pairs bearing an elongated apical club/gripping area with one setal type; 2); Cyclestherida have one clasper pair with clusters of molariform setae on the gripping area and at the movable finger apex; and 3) Laevicaudata have one clasper pair, but have incorporated an additional limb portion into the clasper palm and bear a diverse set of setae. J. Morphol. 278:523–546, 2017. © 2017 Wiley Periodicals, Inc.     

Ultrastructure and distribution of sensilla on the maxillary and labial palps of Chlorophorus caragana (Coleoptera: Cerambycidae)

Chlorophorus caragana is a species of long‐horned beetle that damages Caragana davazamcii Sancz. (Fabales: Papilionaceae) bushes in desert areas in China. The beetles cause substantial damage to local forestry plantations and the environment. Sensilla on the maxillary and labial palps of coleopterans a allow the insects to recognize their host plants. We used scanning and transmission electron microscopy to study the ultrastructure, distribution, and abundance of various sensilla on the maxillary and labial palps of C. caragana. We found four types of sensilla including ten subtypes: one of Böhm's bristles, three of sensilla chaetica, one of digitiform sensilla, and five of sensilla twig basiconica. The types and distribution of the sensilla on the maxillary and labial palps were highly similar between males and females. Finally, this article discusses the functions of the sensilla of related species in recognizing hosts and the significance of gustation studies in the context of the control of C. caragana.     

Placental morphology in two sympatric Andean lizards of the genus Liolaemus (Reptilia: Liolaemidae)

Viviparity is a remarkable feature in squamate sauropsids and it has evolved multiple times in parallel with the formation of a placenta. One example of this repeated evolution of viviparity and placentation occurs in the species‐rich South American genus Liolaemus with at least six independent origins of viviparity. However, evolutionary studies of placentation in this genus are limited by a lack of data on placental morphology. The aim of this study is to describe and compare the microanatomy and vessel diameter (Dv, a function of blood flow) of the placenta using scanning electron microscopy (SEM) and confocal laser scanning microscopy (cLSM) in two sympatric Andean viviparous but highly divergent species, Liolaemus robustus and Liolaemus walkeri. We found interspecific differences in cell types in the chorion, allantois, and omphalopleure that may be explained by divergent phylogenetic history. Time elapsed since divergence may also explain the pronounced interspecific differences in vessel diameter, and within each species, there are strong differences in Dv between tissue locations. Both species show features to improve gas exchange in the chorioallantoic placenta including absence of eggshell, large Dv in the allantois (L. robustus) or embryonic side of the uterus (L. walkeri), and when present, microvillous cells in the allantois (L. walkeri). Both species also show features that suggest transfer of nutrients or water in the omphaloplacenta, including an almost complete reduction of the eggshell, secretive material (L. robustus), or vesicles (L. walkeri) on cell surface uterus, and when present specialized cells in the omphalopleure (L. walkeri). No statistical differences in Dv were found among stages 32–39 in each species, suggesting that a different mechanism, other than enhanced blood flow, might satisfy the increased oxygen demand of the developing embryos in the hypoxic environments of the high Andes. J. Morphol. 276:1205–1217, 2015. © 2015 Wiley Periodicals, Inc.     

Morphology and ultrastructure of Siberian sturgeon (Acipenser baerii) spermatozoa using scanning and transmission electron microscopy

BACKGROUND INFORMATION: Available data concerning the sperm morphology of teleost fishes demonstrate wide variation. In the present study, the spermatozoa of Siberian sturgeon (Acipenser baerii Brandt, 1869), a chondrostean fish, was investigated. In contrast with teleost fish, chondrostean spermatozoa have a head with a distinct acrosome, whereas other structures, such as a midpiece and a single flagellum, are present in spermatozoa of most species. RESULTS: The average length of the head including the acrosome and the midpiece was 7.01+/-0.83 microm. Ten posterolateral projections derived from the acrosome were present on a subacrosomal region, with mean lengths of 0.94+/-0.15 microm and widths of 0.93+/-0.11 microm. The nucleus consisted of electrodense homogeneous nuclear chromatin. Three intertwining endonuclear canals, bound by membranes, traversed the nucleus longitudinally from the acrosomal end to the basal nuclear fossa region. There were between three and six mitochondria, two types of centrioles (proximal and distal) in the midpiece and two vacuoles composed of lipid droplets. The flagellum (44.75+/-4.93 microm in length), originating from the centriolar apparatus, had a typical 9+2 eukaryotic flagellar organization. In addition, there was an extracellular cytoplasm canal between the cytoplasmic sheath and the flagellum. CONCLUSIONS: A principal components analysis explained the individual morphological variation fairly well. Of the total accumulated variance, 41.45% was accounted for by parameters related to the head and midpiece of the sperm and the length of the flagellum. Comparing the present study with previous studies of morphology of sturgeon spermatozoa, there were large inter- or intra-specific differences that could be valuable taxonomically.     

纤毛虫念珠异列虫射出胞器的超微结构观察

应用扫描电镜术和透射电镜术显示,纤毛虫念珠异列虫(Anteholosticha monilata)的射出胞器早期发生在细胞质深处,附近有不同类型的囊泡结构。成熟后射出胞器向表膜迁移,结构由不同电子密度片层的体部、结晶状的中心轴杆部和多层膜的帽部组成。受外界刺激时胞器冲破皮层射出,形态呈"蘑菇"状。据上述观察结果推测:该射出胞器具有防御作用,它可能起源于高尔基体活动产生的小泡;在亲缘关系较近的纤毛虫中,其射出胞器可能具有相似的分化特征。     

Microscopic analysis and seasonality of gemma production in the freshwater red alga Hildenbrandia angolensis (Hildenbrandiales, Rhodophyta)

The development and release of the unique vegetative propagules of the freshwater encrusting alga Hildenbrandia angolensis Welwitsch ex West et West, gemmae, were studied using several different microscopic and histochemical techniques. In addition, the seasonality of gemma production was monitored bimonthly over a 12‐month period in two spring‐fed streams in Texas, USA. Gemmae differentiate within the thallus and are subsequently released from the surface of the crust. Release of the gemmae most likely occurs by digestion of surrounding cells, as suggested by the presence of starch granules and lipid globules in the region between the released gemma and the thallus. The initial separation of the gemmae from the thallus occurs from the sides of the gemma or the bottom, or possibly simultaneously. Contrary to previous studies, we have observed that gemma production occurs endogenously within the thallus of freshwater Hildenbrandia, rather than on the surface of the crust in raised structures. Histochemical tests and electron microscopic examination indicate that the cells of the gemmae contain a large amount of floridean starch. The starch granules frequently form rings surrounding the nuclei of both gemma and thallus cells; a feature infrequently reported for florideophyte red algae. Our seasonality investigations indicate that large fluctuations in gemma production occur over 1 year, but at least some gemma production continues year‐round in the streams examined.