The application of scanning electron microscopy to the systematics of the neotropical Peripatidae (Onychophora)

The taxonomy of the New World Peripatidae is poorly known both because of their rarity and difficulty in the determination of specimens. The distribution of papillae on the dorsal integument is an important taxonomic; character but is difficult to interpret under the light microscope. In this study the integument of a range of New World onychophoran species was studied using scanning electron microscopy. Twenty-one species were examined. Three species of Peripatopsidae were also studied for comparison. This technique revealed (a) the pattern of distribution of papillae on the integument, and (b) the morphology of the papillae. A pattern of three smaller papillae between two large was common to many species. Differences observed in some species were probably modifications of this basic pattern. There was interspecific variation in the number of scales in the apical and basal pieces of the papillae. The specimens examined fell into two main groups: (1) species with more than three scale ranks in the apical piece ( Oroperipatus and Peripatus ) and (2) species with three or fewer scale ranks ( Epiperipatus, Macroperipatus and others). The results thus support a distinction between Epiperipatus and Peripatus . However Macroperipatus is shown not to be a natural group. The relationships of some species which did not fit into this pattern are discussed. This paper shows scanning electron microscopy to be a potentially useful technique in a revision of the New World Peripatidae.     

Mode of infection of the corn earworm (Heliothis zea) by Beauveria bassiana as revealed by scanning electron microscopy

Conidia from highly pathogenic mutants of Beauveria bassiana germinate quickly (within 18 hr) on the surface of corn earworm larvae (Heliothis zea) and immediately begin penetration of the cuticle. Enzymes produced by the penetrating hyphae degrade the cuticle since holes are formed at the point of entry. Clustering of conidia around nodules of larvae is often seen, but penetration is not restricted to such areas. Direct evidence is presented to show that conidia can also germinate inside of spiracle openings and could invade larvae by this route. Once inside the hemocoel, the fungus multiplies extensively; however, larval death occurs with only minimal breakdown of internal tissues. During mummification, outgrowths of fungal hyphae occur first and most extensively in the intersegmental regions of larvae. Conidia from mutants exhibiting low levels of pathogenicity are either significantly delayed or do not germinate on larval surfaces. When germination does occur, hyphae from such mutants do not penetrate immediately; instead, extensive surface hyphal growth, with or without eventual penetration of the integument, is evident.     

Description of the larva of Lopesia spinosa Maia (Diptera,Cecidomyiidae) and new occurrences of the species

The hitherto unknown larva of Lopesia spinosa Maia (Diptera: Cecidomyiidae) is described and the geographical distribution of the species is extended in Brazil to Delfinópolis in Minas Gerais; Altinópolis and Jundiaí in São Paulo. Diagnostic characters of the species and illustration of the larva are presented.     

微红梢斑螟(鳞翅目:螟蛾科)成虫触角感器的扫描电镜观察

通过扫描电镜对微红梢斑螟雌、雄成虫触角的外部形态及感器进行观察,结果表明,微红梢斑螟雌、雄成虫触角共观察到10类感器.其中,毛形感器(Ⅰ、Ⅱ型)、刺形感器(Ⅰ、Ⅱ型)、耳性感器、腔锥形感器、Bǒhm氏鬃毛共7类感器在雌、雄虫触角上均有分布;而栓锥形感器仅在雌虫触角上被发现,钟形感器和鳞形感器这2类感器仅在雄虫触角上被发...     

Light microscopy and scanning electron microscopy studies on the reduction of the tongue microstructures in the white stork (Ciconia ciconia,Aves)

The structure of the tongue in the white stork (Ciconia ciconia) is observed macroscopically and under light and scanning electron microscopy. Our observations of the tongue reveal a rare terminal reduction of the size of the tongue and microstructures of the lingual mucosa among the investigations of birds published so far. The short, triangular tongue with a pointed tip is approximately 2.5 cm long in the adult and is situated in the caudal part of the oral cavity close to the laryngeal prominence. On the dorsal surface of the tongue, no typical mucosa microstructures like lingual papillae, median groove or lingual prominence are observed. The main structure of the tongue is composed of rostral part of hyoid apparatus, that is, entoglossal cartilage connects with basihyoid. Very thin mucosa is composed of fibrous connective tissue covered with orthokeratinized epithelium. No lingual glands and muscles are observed in the lamina propria of mucosa. Even though the triangular shape of the tongue in the white stork is typical for birds, the inner structure of the reduced organ is composed only of flat cartilagineous entoglossum of hyoid apparatus. During feeding behaviour of the white stork, the food transportation in oral cavity called cranio‐inertial transport is undoubtedly affected by structural reduction of the tongue.     

Gills of the medaka (Oryzias latipes): A scanning electron microscopy study

The general morphology and surface ultrastructure of the gills of adult and larvae medaka (Oryzias latipes) were studied in freshwater and seawater using scanning electron microscopy. The gills of all examined fish were structurally similar to those of other teleosts and consisted of four pairs of arches supporting (i) filaments bearing lamellae and (ii) rakers containing taste buds. Three cell types, specifically pavement cells, mitochondria‐rich cells (MRCs), and mucous cells, constituted the surface layer of the gill epithelium. Several distinctive characteristics of medaka gills were noted, including the presence of regularly distributed outgrowth on the lamellae, enlarged filament tips, the absence of microridges in most pavement cells in the filament and lamellae and the presence of MRCs in the arch at the filament base. A rapid mode of development was recorded in the gills of larval fish. At hatching, the larvae already had four arches with rudimentary filaments, rakers, and taste buds. The rudimentary lamellae appeared within 2 days after hatching. These results suggest the early involvement of larval gills in respiratory and osmoregulation activities. The responses of the macrostructures and microstructures of gills to seawater acclimation were similar in larvae and adult fish and included modification of the apical surface of MRCs, confirming the importance of these cells in osmoregulation. The potential roles of these peculiarities of the macrostructures and microstructures of medaka gills in the major functions of this organ, such as respiration and osmoregulation, are discussed.     

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.     

The tegumental surface of Phyllodistomum conostomum (Olsson, 1876) (Digenea), revealed by scanning electron microscopy

The external surface of P. conostomum is characterized by relatively large ridges encircling the anterior part of the worm at regular intervals. On the posterior part depressions on the ventral side at regular intervals and relatively small ridges on the dorsal side are present. Ventroposteriorally cobblestone-like protuberances observed are arranged in longitudinal rows. No corresponding arrangement was found dorsally. Only domed papillae (with and without a central knob) were observed, tentatively identified as sensory organs. The regular pattern of these papillae on the ventral and oral sucker is described, in addition to their arrangement ventrally and at the anterior end. A frontal pit anterior of oral suckers and a notch at the posterior end are figured and briefly described. No spines were observed on the body tegument.     

External sense receptors in microdrile oligochaetes (Annelida,Clitellata) as revealed by scanning electron microscopy: Typology and patterns of distribution in the main taxonomic groups

This work summarizes the observations on 30 species of microdriles belonging to the families Naididae (Rhyacodrilinae, Pristininae, Naidinae, Phallodrilinae, and Tubificinae), Phreodrilidae, Lumbriculidae, and Enchytraeidae using scanning electron microscopy. The lumbricid Eiseniella tetraedra, a megadrile species common in typical microdrile habitats, was used for comparison. Microdriles display external ciliate sense structures along the entire body; even at the clitellum and in budding and regeneration zones. According to the shape of the cilia, these sense structures can be divided into receptors of blunt cilia, receptors of sharp cilia, and composed receptors. Sense receptors can be morphologically unconspicuous or clearly defined on sensory buds or papillae. All microdriles studied have receptors of blunt cilia. Enchytraeids have characteristic receptors of short cilia. Pristina (Pristininae), Chaetogaster, Ophidonais, and Stylaria (Naidinae) have receptors of long blunt cilia. Composed receptors were found only in some microdriles and E. tetraedra. Receptors of sharp cilia have been found in most microdriles. Enchytraeids might be the only exception, but sharp cilia are probably present in the amphibiotic Cognettia sphagnetorum. Sensory cells with long sharp cilia might play a rheoreceptor role, and their presence in E. tetraedra and C. sphagnetorum would imply the reappearing of an ancient character that was probably lost with the transit from aquatic to terrestrial habitats. Some lumbriculids have ciliated fields. Anatomically, these structures appear as intermediate between the typical isolate sensory structures of microdriles and the sensillae of the hirudineans. The general pattern in microdriles is that uniciliate receptors and multiciliate receptors are separated, which supports the presumed aquatic origin of the clitellates. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

New Host and Locality Records for the Ixodes Auritulus (Acari: Ixodidae) Species Group, with a Review of Host Relationships and Distribution in the Neotropical Zoogeographic Region

New Neotropical records are presented for ticks belonging to the Ixodes auritulus Neumann, 1904, species group, together with a review of hosts and localities from which members of this complex have previously been collected. The range of the I. auritulus species group is now understood to include Colombia, and 15 bird species are listed as new hosts. From Guatemala to southern Argentina and Chile, specimens of the I. auritulus group have been found on birds belonging to the orders Ciconiiformes, Columbiformes, Falconiformes, Galliformes, Passeriformes, Piciformes, Procellariiformes and Tinamiformes. Passeriform birds are probably the principal hosts, sustaining tick populations throughout the Neotropics. Collection data have yielded four areas – southern South America (from 56° S to 51° S), southern Brazil (25° S–22° S), south-central Peru (14° S–10° S) and Central America (10° N–15° N) – where the I. auritulus group appears to commonly parasitize birds, but additional collections may show that the range of this complex is less discontinuous than currently perceived. Several morphological differences are described for ticks within and among these areas, but it is still unclear whether the I. auritulus group comprises more than one species.     

Light microscopy and scanning electron microscopy of the In vitro evagination process of Echinococcus multilocularis protoscolices

Marchiondo A. A. and Andersen F. L. 1984. Light microscopy and scanning electron microscopy of the in vitro evagination process of Echinococcus multilocularis protoscolices. International Journal for Parasitotogy14:151–157. During histogenesis of the protoscolices of Echinococcus multilocularis, the apical portion of the protoscolex consisting of the suckers, rostellum and hook region develops as an introversion and invagination within the tissue of the basal portion. In vitro incubation of protoscolices in evagination fluid stimulates the emergence of the apical portion. The initiation of evagination is first detected by a surface change in the basal portion. The smooth contour of this surface which lacks microtriches becomes transformed into tegumental indentations that form transverse and longitudinal furrows within the basal tegument as the protoscolices contract and expand, respectively. An orifice formed at the site or junction where the apical portion is invaginated begins to expand laterally in order to allow emergence of the suckers. The hooks are arranged within the invaginated protoscolex with blades directed towards the basal orifice, the handles directed towards the peduncle and the guards directed laterally. This arrangement persists throughout the evagination of the suckers and rostellum until the apical dome of the hook region emerges, thereby rotating the blades laterally in the direction of the peduncle and rotating the handles and guards medially to assume a coronal arrangement. Evagination is an asynchronous event and therefore allows observation of individual protoscolices in various stages of emergence.     

A benign approach to the preparation of freshwater bryozoan statoblasts for scanning electron microscopy (SEM) imaging

Abstract

Several different species of freshwater Bryozoa, belonging to the genera Plumatella, Rumarcanella and Fredericella, were detected within the Northern Mallee Pipeline (NMP) system in Victoria, Australia, that required definitive identification. These organisms produce asexual buds called statoblasts, with valves composed of sclerotised chitin that bear minute micro-ornamentations of considerable taxonomical significance. Imaging and analysis of these distinctive micro-ornamentations using scanning electron microscopy (SEM) is often employed for species identification. Meticulous preparation of statoblast samples is therefore required that necessitates the removal of adhering debris, dehydration and drying—whilst mitigating specimen damage and distortion. This technical note describes an approach whereby each of these three steps have been individually designed to be as benign as possible, using mild detergent/sonication to remove debris, a gradual and gentle dehydration procedure using ethanol, and critical point drying. For the overall process, these methods are chosen to optimise control and to minimise the use of harsh and hazardous chemicals.     

Scanning electron microscopy of taxonomic diagnostic criteria of the freshwater sponge,Heteromeyenia tubisperma (Potts, 1881) (Porifera : Spongillidae)

Taxonomic diagnostic criteria of the spongillid freshwater sponge, Heteromeyenia tubisperma (Potts, 1881) were examined using scanning electron microscopy. The species is characterized by a gemmule which bears an unusually long, prominent porous tube. The application of SEM to the systematic studies of the freshwater sponges provides diagnostic capabilities not available with the light microscope. It is desirable that a key, coupled with a reference atlas of scanning electron micrographs illustrating taxonomic diagnostic criteria of freshwater sponge species, particularly utilizing type specimens, be developed.     

Analysis of Vero cell growth behavior on microcarrier by means of environmental scanning electron microscopy

By using environmental scanning electron microscopy, the morphological changes of Vero cells attached to and grown on the microcarrier Cytodex-3 were observed, and their behavior of adhesion, spreading and proliferation was analyzed. The effect of exogenous fibronectin/ laminin on adhesion and spreading of MCC/Vero cell was studied. The images of ESEM showed that expansion of cell growth was directed toward vacancy space. The growth curve and cell concentration change during the whole culture process were obtained from the statistical counting method based on ESEM images and the crystal violet method. The growth rate of Vero cells increases with increasing the concentration of cell inoculation, that is, the specific growth rate increases quickly with increasing the concentration of cell inoculation. When serum concentration in medium #199 ranged from 5% to 10%, experimental results indicated that serum concentration is one of the important factors influencing cell growth, particularly in the cell adhesio     

Ixodid ticks feeding on humans in South Africa: with notes on preferred hosts,geographic distribution,seasonal occurrence and transmission of pathogens

This paper records the identities of 558 ixodid ticks feeding on 194 humans in South Africa. These ticks belonged to 20 species in six genera and those most frequently encountered were Amblyomma hebraeum, Haemaphysalis leachi, Hyalomma marginatum rufipes, Hyalomma truncatum, Rhipicephalus appendiculatus, Rhipicephalus gertrudae and Rhipicephalus simus. With the exception of the larvae of R. appendiculatus, the incidents of these ticks feeding on humans correlated well with their seasonal occurrences on preferred hosts. Ticks were also collected at monthly intervals, for 14 consecutive months, from the clothing of a game-guard providing protection for field-workers engaged in the collection, by means of flannel strips, of free-living ticks from the vegetation of four localities in the southern region of the Kruger National Park. In addition, with the exception of 3 months when the particular worker was absent, ticks that fed on one of the field-workers were collected over the same 14-month period. A total of 54,429 free-living ticks belonging to 14 species and six genera were collected from the vegetation at the four localities during this time and 3751 ticks belonging to 11 species and six genera from the clothing of the game-guard. The larvae of A. hebraeum and Boophilus decoloratus were the most numerous of the immature ticks, and H. leachi and R. simus of the adults on both the vegetation and the guard’s clothing. Ticks fed on the field-worker on six occasions and 14 were collected, all of which were A. hebraeum larvae. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antigens and glycoproteins of larvae, nymphs and adults of the tick Ixodes ricinus

Abstract Protein components of homogenates of unfed larvae and nymphs of Ixodes ricinus (L.), and of ovary, haemolymph, Malpighian tubules, rectal ampulla, fat body, integument, salivary glands and midgut of partially fed adult females were studied for their antigenicity and carbohydrate moieties using immunoblotting and lectin affinity blotting (LAB) techniques. Comparing the individual anti-larval, anti-nymphal and anti-adult immune sera for their capacity to recognize the specific and trans-stadially cross-reactive antigenic proteins, larval feeding induced the most effective humoral response. The majority of immunogens recognized by rabbit anti-tick immune sera are glycoproteins. Most of the glycosylated antigens were modified with N-type glycans; however, O-type glycans were also demonstrated in some antigens. The correlation of the type of glycosylation with antigenicity, and the sharing of common antigenic epitopes by various tissues, are discussed.