Structure of the cuticle of the common house cricket with reference to the location of lipids

Cuticle segments from the thorax, abdomen, and jumping legs of the house cricket. Acheta domesticus, were examined using histological techniques for light microscopy, scanning and transmission electron microscopy, and direct examination of frozen-fractured cuticle. The surface of untreated cuticle is covered by a lipid film which obscures fine surface detail. Standard EM preparative procedures, as well as washing the cuticle with ethanol before examination, remove this film exposing previously covered openings to dermal gland ducts and wax canals. An epicuticle, exocuticle, mesocuticle, endocuticle, and a deposition layer were present in all transverse sections of cuticle. Light microscopy showed that the exocuticle and mesocuticle are heavily impregnated with lipids, whereas there is little lipid associated with the endocuticle. Frozen-fractured cuticle clearly shows the ‘plywood’ structure of the meso- and endocuticle, while the exocuticle fractures as if it were a solid sheet. The epicuticle is composed of a dense homogeneous layer, cuticulin, outer epicuticle, and the outer membrane. Superficial wax was detected only in cuticle samples prepared using vinylcyclohexane dioxide as a polar dehydrant. The results were used to construct a comprehensive model of the cuticle of A. domesticus.     

The structure of the wall plate in chthamalus depressus (poli)

The structure of the calcitic shell of extreme hypobiotic Chthamalus depressus (Poli) using untreated, treated, and polished material has been investigated by scanning electron microscopy, and supplemented by observations on normal forms and C. Stellatus (Poli). The laterale has been largely used. The plate is made up of prisms consisting of stacks of units ≈ 5 μm high; the prisms are separated by matrix and intraprismatic organic matter may also be present. The inner side of the plate is penetrated by holes. The structure of the wall plate is reflected in that of the sheath. Epicuticular lamina run across the wall plates separating the stacks of prisms. Attention is drawn to the possible implications with respect to the recent controversy regarding the form of chitin in crustacean endocuticle.

The various structures give the surface a ‘banded’ appearance. From the available data on growth rate, shape, and moulting frequency, estimates are made of the expected size of these bands; the results agree reasonably well with the observations.

The frequency of the smaller bands would seem to be endogenously determined by processes taking place within an intermoult period.     

Morphology and molecular phylogeny of the benthic dinoflagellates (Dinophyceae,Peridiniales) Amphidiniopsis crumena n. sp. and Amphidiniopsis nileribanjensis n. sp.

Amphidiniopsis is a benthic, heterotrophic and thecate dinoflagellate genus that has a smaller epitheca and larger hypotheca. The genus contains 24 described species, but is considered to be polyphyletic based on morphological characters and molecular phylogenetics. In this study, two new species were discovered from two distant sampling localities, Amphidiniopsis crumena sp. nov. from Japan, and Amphidiniopsis nileribanjensis sp. nov., from Australia. These species have a uniquely shaped, additional second postcingular plate. Both species are dorsoventrally flattened, an apical hook is present, and have six postcingular plates. The plate formula is: APC 4′ 3a 7″ ?C 4?S 6″′ 2″″. The cells of these species were examined with LM and SEM, and molecular phylogenic analyses were performed using 18S and 28S rDNA. These species are distinguished by the presence of spines on the hypotheca and touching of the sixth postcingular plate and the anterior sulcal plate. Their shape and disposition of several thecal plates also differ. Molecular phylogenetic analyses showed that the two new species formed a monophyletic clade and did not belong to any morphogroup proposed by previous studies. Considering the morphological features and the molecular phylogenetic results, a new morphogroup is proposed, Amphidiniopsis morphogroup VI (‘crumena group’).     

The female postabdomen and genitalia of the basal moth family Heterobathmiidae (Insecta: Lepidoptera): Structure and phylogenetic significance

Female Heterobathmia have the segments behind VIII forming a compact ‘terminal unit’ with a large saddle-shaped dorsal plate and a membranous ventroposterior surface bearing the separate gonopore and anus. While females of most of the nine known species are overall similar, Heterobathmia valvifer is unique amongst lepidopterans in possessing paired ventral appendages (‘ovipositor valves’) arising from the intersegmental groove following segment VIII; evidence from musculature contradicts an interpretation of these appendages structures as ‘true’ ovipositor valves. The ventroposterior wall of the terminal unit in H. valvifer bears paired sclerites, possible homologues of the ‘ventral rods’ in basal Lepidoptera-Glossata. In Heterobathmia megadecella sclerites on paired longitudinal elevations in comparable positions probably are/include homologues of these sclerites. Their similarity with paired sclerotizations in the corresponding region of hydrobiosid caddisflies is noted. A prominent frame-like sclerotization in the genital chamber, located in front of the spermathecal duct origin, is present only in H. megadecella.Putative heterobathmiid autapomorphies include an enlarged ‘subgenital plate’ on venter VIII, absence of apophyses on segment VIII, shortened apophyses on the terminal unit, multilobed accessory glands (but their ‘type 1’ secretory epithelium is plesiomorphic at this level), a conspicuous papilla in the chamber cuticle bearing the opening of the ductus bursae on its apex, and inwards-pointing spines in the ductus bursae. A variably developed thickening of the anterior genital chamber intima is another putative family autapomorphy, while an extreme thickening of the posterior intima seen in Heterobathmia pseuderiocrania is not of general occurrence in heterobathmiids. A sistergroup relationship between Heterobathmiidae and Glossata is supported by their fully developed ‘2-compartment section’ of the spermathecal duct and losses of some likely lepidopteran groundplan muscles.     

Structural heterogeneity of the plasmalemma of the yeast,Schwanniomyces occidentalis,induced by substrate

The growth of the yeast Schwanniomyces occidentalis on hydrocarbons (C₁₂?C₂₀) is followed by the formation of spherical invaginations. They are inwardly directed and border the ‘canals’ of the cell wall forming with them a single complex. The invaginations differ from the rest (smooth) part of the plasmalemma in the density of intramembrane particles. There is also a significant difference in the distribution of intramembrane particles in the plasmalemma of S. occidentalis grown on hydrocarbons and glucose. Invaginations and ‘canals’ are considered as a manifestation of the structural heterogeneity of the yeast cell envelope induced by a hydrocarbon substrate and, evidently, conditioned by adaptive processes.     

Linking hyperelastic theoretical models and experimental data of vaginal tissue through histological data

Mechanical characterization of living tissues and computer-based simulations related to medical issues, has become increasingly important to improve diagnostic processes and treatments evaluation. This work proposes a link between the mechanical testing and the material model predictions through histological data of vaginal tissue. Histological data was used to link tensile testing experiments with material-dependent parameters; the approach was adequate to capture the nonlinear response of ovine vaginal tissue over a large strain range.The experimental data obtained on a previous study, has two main components: tensile testing and histological analysis of the ovine vaginal tissue. Uniaxial tensile test data and histological data were collected from three sheep groups: virgins, pregnant and parous. The distal part of vaginal wall was selected since it is prone to tears induced by vaginal delivery.The HGO (Holzapfel-Gasser-Ogden) model parameters were fitted using a stochastic approach, namely the Simple Genetic Algorithm (SGA). The SGA was able to fit the experimental data successfully (R² > 0.986). The dimensionless coefficient ξ, was highly correlated with histological data. The ratio was seen to increase linearly with increasing collagen content.Coefficient ξ brings a new way of interpreting and understanding experimental data; it connects the nonlinear mechanical behaviour (tensile test) with tissue’s morphology (histology). It can be used as an ‘inverse’ (approximate) method to estimate the mechanical properties without direct experimental measurements, through basic histology.In this context, the proposed methodology appears very promising in estimating the response of the tissue via histological information.     

Distribution of calcium phosphate in the exoskeleton of larval Exeretonevra angustifrons Hardy (Diptera: Xylophagidae)

Distribution and organisation of the mineral, amorphous calcium phosphate (ACP), has been investigated in the exoskeleton of the xylophagid fly larva Exeretonevra angustifrons Hardy. While head capsule and anal plate are smooth with a thin epicuticle, the epicuticle of the body is thicker and shows unusual micro-architecture comprised of minute hemispherical (dome-shaped) protrusions. Electron microprobe analysis and energy dispersive spectroscopy revealed heterogeneity of mineral elements across body cuticle and a concentration of ACP in the epicuticle, especially associated with the hemispherical structures. Further imaging and analysis showed the bulk of the ACP to be present in nano-sized granules. It is hypothesised that the specific distribution of ACP may enhance cuticular hardness or durability without reducing flexibility.     

Cleaner Wrasses Keep Track of the ‘When’ and ‘What’ in a Foraging Task1

In recent years evidence has accumulated that at least some animals can remember the ‘what’, ‘where’ and ‘when’ of personal experiences. Currently, evidence for such ability is taxonomically restricted to birds and mammals. Here, we demonstrate for the first time that cleaner wrasses Labroides dimidiatus are able to remember when they interacted with what after a single event. In nature, cleaners remove ectoparasites from other reef fishes, so‐called clients. Clients are depleted, non‐stationary food patches at the end of an interaction and replenished only after a delay. In our experiments, we presented twelve cleaners every 2.5 min, a choice between two of a total of four plates with different colours and patterns. One plate was always accessible but contained a non‐preferred food item while the other three contained a preferred food item, but allowed a next feeding event only after 5, 10 or 15 min. Thus, to maximise food intake, cleaners had to remember for each choice when they had last interacted with which plate. When confronted with two plates offering preferred food, cleaners showed an overall significant preference for the plate that allowed access during the trial. For six cleaners, the preference was significant. Also, on trials involving the always accessible plate, cleaners discriminated between trials in which they had to eat the non‐preferred food and trials on which they could eat the preferred food. In conclusion, cleaners are able to track the ‘when’ and ‘what’ (or possibly ‘who’) within a biologically meaningful time period.     

Effects of Silicon-Limitation on Growth and Morphology of Triparma laevis NIES-2565 (Parmales,Heterokontophyta)

The order Parmales (Heterokontophyta) is a group of small-sized unicellular marine phytoplankton, which is distributed widely from tropical to polar waters. The cells of Parmales are surrounded by a distinctive cell wall, which consists of several siliceous plates fitting edge to edge. Phylogenetic and morphological analyses suggest that Parmales is one of the key organisms for elucidating the evolutionary origin of Bacillariophyceae (diatoms), the most successful heterokontophyta. The effects of silicon-limitation on growth and morphogenesis of plates were studied using a strain of Triparma laevis NIES-2565, which was cultured for the first time in artificial sea water. The cells of T. laevis were surrounded by eight plates when grown with sufficient silicon. However, plate formation became incomplete when cells were cultured in a medium containing low silicate (ca. <10 µM). Cells finally lost almost all plates in a medium containing silicate concentrations lower than ca. 1 µM. However, silicon-limitation did not affect growth rate; cells continued to divide without changing their growth rate, even after all plates were lost. Loss of plates was reversible; when cells without plates were transferred to a medium containing sufficient silicate, regeneration of shield and ventral plates was followed by the formation of girdle and triradiate plates. The results indicate that the response to silicon-limitation of T. laevis is different from that of diatoms, where cell division becomes inhibited under such conditions.     

Morphological differentiation of the central visual cells R7/8 in various regions of the blowfly eye

The central rhabdomeres in the retina of the blowfly Calliphora erythrocephala and the house fly Musca domestica are not structurally uniform. In Calliphora, four classes of central rhabdomeres were found; they are formed by a total of seven types of central visual cells, clearly distinguished by the following structural features: length of the rhabdomeres R7 or R8, position of the nucleus, rhabdomere twist, fine structure in the R7/R8 transition region, and cross-sectional area of the rhabdomeres. In the lateral part of the eye only the most common central-rhabdomere class, ‘sl.’ is present, whereas in the frontal and dorsal parts classes ‘sl’ and ‘ls’ are found in a particular numerical ratio. Near the frontal eye margin the rare class ‘per’ also appears, with two separate rhabdomeres, R7per and R8s; the morphological properties of R7per are midway between those of peripheral and central visual cells. The special ommatidia at the dorsal margin of the eye are characterized by the central rhabdomeres ‘marg’. The known functional properties of the visual cells in the fly eye can be readily assigned to these classes (Table 1, Fig. 12). The non-uniform distribution of the various kinds of central rhabdomeres suggests functional differentiation of the eye region.     

The subependyma of the primate, slow loris (Nycticebus coucang coucang)

The subependymal plate of the primate slow loris (Nycticebus coucang coucang) has been studied by electron microscopy. It is composed of a mixed population of several cell types in which the subependymal cells preponderate. Free subependymal cells are found in the ‘border area’ near the corpus callosum or the neuropile of the caudate nucleus. In common with the subependymal cells they show a scanty cytoplasm containing mostly free ribosomes. Typical neuroglial cells namely, microglia, astrocytes and oligodendrocytes are also identified in this region. Among the various cell types mentioned there are present also a few occasional cells which have features bearing a resemblance to the subependymal cell on the one hand and to the microglia on the other. The morphological evidence suggests that in parallel with the macroglia the microglia could be derived by stepwise transformation of the subependymal cells.     

Cuticular adaptations in two parasitic copepods in relation to their modes of life

The structure, histochemistry, and possible functional properties of the cuticle in two parasitic copepods Pennella elegans Gnanamuthu and Caligus savala Gnanamuthu have been studied: the former is partially embedded in the host while the latter is an ectoparasite capable of free swimming.In Pennella elegans the cuticle of the embedded anterior region of the body is soft, colourless, and lacks an outer epicuticle while that of the posterior exposed part is pigmented and hard. Conspicuous in the cuticle of the ventral region of the head are pore canals which, though not chitinized, are functional even in the intermoult stage: these canals may be involved in the transport of nutrient materials from the host. The horns, which serve to fix the parasite firmly in the host tissues, are covered by cuticle in which the epicuticle and outer layers of the procuticle are hardened by formation of disulphide linkages. The cuticle of the neck region is not hardened and the procuticle in this region shows transverse regions of dense and light zones probably related to the coiling of the neck during penetration. The epicuticle is two layered in the cuticle of the exposed posterior region, the inner epicuticle and outer region of the procuticle being partially hardened by phenolic tanning so confer rigidity and resistance. The cuticle of the plumes is soft and devoid of an outer lipid epicuticle and so possibly adapted for a respiratory function.In Caligus savala, the epicuticle is two layered, and the procuticle has pigmented, calcified, and uncalcified layers. The cuticle is hardened by phenolic tanning as well as by calcification thus recalling the cuticular organization of decapod crustaceans.     

Incorporation of [14C]cinnamate into hydrolase-resistant components of the primary cell wall of spinach

[¹⁴C]Cinnamate was taken up very rapidly by cultured spinach cells and completely incorporated into low-MW conjugates within 20 min. The ¹⁴C-labelled products were similar whether the [¹⁴C]cinnamate was supplied continuously over a period of hours via a peristaltic pump or instantaneously. Radioactivity was slowly recruited from the low-MW pool into aromatic components of the cell-wall fraction. Saponification of the radioactive wall fraction yielded, in addition to radioactive ferulate and p-coumarate, large amounts of ethyl acetate-soluble radioactive material with the properties of oxidatively coupled phenols. The coupled material was associated with the most highly ‘Driselase’-resistant fractions of the cell wall. In contrast, ‘Driselase’ released most of the wall's ferulate and p-coumarate on disaccharide fragments. It is suggested that the oxidatively coupled phenols are formed from simpler phenols by peroxidase and that they cross-link the polysaccharides to which they are attached, making these polysaccharides relatively ‘Driselase’-resistant.     

Cell wall synthesis in cotton roots after infection with Fusarium oxysporum

Fusarium oxysporum f. sp. vasinfectum penetration hyphae infect living cells in the meristematic zone of cotton (Gossypium barbadense L.) roots. We characterized wall modifications induced by the fungus during infection of the protodermis using antibodies against callose, arabinogalactan-proteins, xyloglucan, pectin, polygalacturonic acid and rhamnogalacturonan I in high-pressure frozen, freeze-substituted root tissue. Using quantitative immunogold labelling we compared the cell walls before and after hyphal contact, cell plates with plasmodesmata during cytokinesis, and wall appositions induced by fungal contact. In the already-existing wall, fungal contact induced only minor modifications such as an increase of xyloglucan epitopes. Wall appositions mostly exhibited epitopes similar to the cell plate except that wall appositions had a much higher callose content. This study shows that wall appositions induced by Fusarium oxysporum hyphae are the result of normal cell wall synthesis and the addition of large amounts of callose. The appositions do not stop fungal growth.     

Structure of the Cuticle of Metadasynemoides cristatus (Chromadorida: Ceramonematidae)

Structure of the cuticle of Metadasynemoides cristatus (Chromadorida: Ceramonematidae) is examined by light, scanning, and transmission electron microscopy. The nematode has more than 600 annuli, and each annulus has eight cuticular plates. Eight longitudinal ridges, beginning on the cephalic capsule, extend the whole length of the body. Where a ridge traverses an annulus, it forms a complicated articulating structure of overlapping vanes. Within the electron-dense cortical layer, from which the cuticular plates are formed, there are spaces crossed by fine fibrillae, forming what have been termed "vacuoles" by light microscopists. There is an epicuticle and a continuous lucent basal layer. There appears to be no median layer. The cuticle lining of the esophagus and that forming the circum-oral ridge is of much simpler construction.     

The validity of the Middle Devonian camerate crinoid species Hexacrinites hieroglyphicus (Goldfuss, 1839) and H. marginatus (Schultze, 1866)

The camerate crinoids Hexacrinites hieroglyphicus (Goldfuss, 1839) and H. marginatus (Schultze, 1866) are valid species known from the Lower Givetian of the synclines of Gerolstein and Hillesheim, Eifel Hills (westernmost Germany). As shown by the refigured holotypes and new material, they are mostly separated by the expressed ornamentation of radials and basals. The radials of H. hieroglyphicus are characterized by prominent, variously formed bulges, stretching preferably in a radiate pattern across most of the plates. They do not reach the low plate boundaries. Vice versa, H. marginatus shows expressed depressions in the central part of the plates, but raised plate margins. The first known crowns of H. marginatus are described; one of them is proposed as neotype for the lost original.