Genes involved in melanin production directly impact insect pigmentation and can affect diverse physiology and behaviours. The role these genes have on sex behaviour, however, is unclear. In the present study, the crucial melanin pigment gene black was functionally characterised in an urban pest, the German cockroach, Blattella germanica. RNAi knockdown of B. germanica black (Bgblack) had no effect on survival, but did result in black pigmentation of the thoraxes, abdomens, heads, wings, legs, antennae, and cerci due to cuticular accumulation of melanin. Sex-specific variation in the pigmentation pattern was apparent, with females exhibiting darker coloration on the abdomen and thorax than males. Bgblack knockdown also resulted in wing deformation and negatively impacted the contact sex pheromone-based courtship behaviour of males. This study provides evidence for black function in multiple aspects of B. germanica biology and opens new avenues of exploration for novel pest control strategies.

Fourteen tomato genotypes, eastern black nightshade, and 35 Lycopersicon accessions were screened for tolerance to acifluorfen. Tolerant and susceptible genotypes occurred in most species. Fifteen genotypes were chosen for further study depending on their fresh weight after acifluorfen treatment Over all 15 genotypes, there was no correlation between trichome density and acifluorfen tolerance; however, in L. esculentum, cultivars with the most trichomes were the most tolerant There was an inverse relationship between stomata density and tolerance. Amount and composition of epicuticular wax and cuticle thickness did not correlate to acifluorfen tolerance.

The effect of ammonium sulfate (AMS) on efficacy and on absorption and translocation of sethoxydim in wild oats and barley was investigated under controlled environmental conditions. Increases in efficacy in the presence of AMS were relatively small. The rate of sethoxydim required to reduce dry weight 50% was reduced from 0.08 kg a.i. ha−1, for both species, to 0.07 and 0.06 kg ha−1 for wild oats and barley, respectively, in the presence of added AMS. In short-term experiments, uptake of 14C from 14C-labeled sethoxydim 0.5 and 1 h after application was increased approximately twofold with the addition of AMS. AMS had little effect on sethoxydim absorption beyond 1 h after application. Translocation at 1 h after application was unaffected by AMS. However, translocation 12 and 24 h after application was increased with AMS. It is postulated that the translocation increase results indirectly from the increase in absorption. The observed increase in absorption with the addition of AMS is evident only when crop oil concentrate (COC) is also present In model systems, the addition of AMS enhanced sorption of sethoxydim into Isolated cuticles but had no effect on movement into excised roots.

Aglaspidid euarthropods are usually preserved as flattened carapaces. We here describe a new species and genus, Gogglops ensifer, from the Ordovician Shaanxi Province, China, which shows the best three-dimensional (3D) preservation yet discovered. We show that the cuticle was originally composed of calcium carbonate, except for the visual surfaces of the eyes which were probably originally organic but have been selectively phosphatized. A review is given of the problems pertaining to the original nature of the aglaspidid cuticle. Gogglops is probably closely related to certain poorly known aglaspidid genera from Ordovician deposits of the Siberian Platform. Phylogenetic analysis indicates that the new genus is closely related to Aglaspis itself, and securely nested within the clade Aglaspidida.

Greenhouse and laboratory experiments were conducted to investigate mechanisms of glyphosate resistance in horseweed populations from Mississippi, Arkansas, Delaware, and Tennessee. A nondestructive leaf-dip bioassay was developed to confirm resistance and susceptibility in individual test plants. A single leaf was excised from each plant, and the petiole and bottom one-fourth of leaf was dipped in a 600 mg ae L−1 glyphosate solution for 2 d followed by visually estimating the injury on a scale of 0 to 10. Plants were classified as resistant (R) if the score was 2 to 3 and susceptible (S) if the score was 5 to 6. 14C-glyphosate solution was applied on the adaxial surface of a fully expanded leaf of the second whorl of four-whorl rosette plants. Plants were harvested 48 h after treatment and radioactivity was determined in treated leaf, other leaves, crown, and roots. Absorption of 14C-glyphosate was similar (47 to 54%) between R and S plants from within and among the four states, suggesting absorption is not involved in glyphosate resistance. The amount of radioactivity translocated from the treated leaf was reduced in R plants compared with S plants. The reduction in translocation of 14C-glyphosate ranged from 28% in Mississippi-R biotype to 48% in Delaware-R biotype compared with their respective S biotypes. Epicuticular wax mass ranged from 6 to 80 μg cm−2 among horseweed biotypes, with no differences between R and S biotypes within each state. Treating two leaves with glyphosate solution at the field use rate (0.84 kg ae ha−1) killed S plants but not R plants (38 to 58% control) regardless of state origin. These results suggest that a simple bioassay can be used to screen biotypes for suspected resistance and that reduced translocation of glyphosate plays a major role in glyphosate resistance in R biotypes of horseweed.

A new species of Tetranchyroderma, T. garraffonii, is described from sublittoral sediments off the coast of Florida, USA. The new species possesses mixed scale types in the form of feathered biancres – a novel discovery for the genus – as well as feathered triancres and ordinary triancres. Biancres consist of a round scale base, a pair of ancre shafts that arise individually from a v-shaped cuticular ridge on the scale, and feathered ancres. Triancres are similar in appearance but have a different ridge pattern. Ordinary triancres occurred in two forms on the lateral sides of the body: a bowl-shaped ancre and a ‘pitchfork’ shaped ancre. Other distinguishing characteristics of the new species include the presence of cephalic tentacles, a papillated fringe to the oral hood, and a single pair of lateral and dorsolateral adhesive tubes at the posterior end. Confocal microscopy verified the presence of a muscular caudal organ and partly muscular vas deferens.

We present a new species of Meliaceae, Cedrela ngobe Köcke, T.D.Penn. & Muellner, from Panama and Costa Rica. A detailed description with illustrations and a distribution map are provided. Based on distribution data and climatic niche modelling, the species is classified as Vulnerable according to IUCN Red List categories.

Nematodes represent one of the most abundant and species-rich groups of animals on the planet, with parasitic species causing chronic, debilitating infections in both livestock and humans worldwide. The prevalence and success of the nematodes is a direct consequence of the exceptionally protective properties of their cuticle. The synthesis of this cuticle is a complex multi-step process, which is repeated 4 times from hatchling to adult and has been investigated in detail in the free-living nematode, Caenorhabditis elegans. This process is known as moulting and involves numerous enzymes in the synthesis and degradation of the collagenous matrix. The nas-36 and nas-37 genes in C. elegans encode functionally conserved enzymes of the astacin metalloprotease family which, when mutated, result in a phenotype associated with the late-stage moulting defects, namely the inability to remove the preceding cuticle. Extensive genome searches in the gastrointestinal nematode of sheep, Haemonchus contortus, and in the filarial nematode of humans, Brugia malayi, identified NAS-36 but not NAS-37 homologues†. Significantly, the nas-36 gene from B. malayi could successfully complement the moult defects associated with C. elegans nas-36, nas-37 and nas-36/nas-37 double mutants, suggesting a conserved function for NAS-36 between these diverse nematode species. This conservation between species was further indicated when the recombinant enzymes demonstrated a similar range of inhibitable metalloprotease activities.

Helminth immunology is a field which has changed beyond recognition in the past 30 years, transformed not only by new technologies from cDNA cloning to flow cytometry, but also conceptually as our definition of host immune pathways has matured. The molecular revolution defined key nematode surface and secreted antigens, and identified candidate immunomodulators that are likely to underpin parasites' success in eluding immune attack. The immunological advances in defining cytokine networks, lymphocyte subsets and innate cell recognition have also made a huge impact on our understanding of helminth infections. Most recently, the ideas of regulatory immune cells, in particular the regulatory T cell, have again overturned older thinking, but also may explain immune hyporesponsiveness observed in chronic helminth diseases, as well as the link to reduced allergic reactions observed in human and animal infections. The review concludes with a forward look to where we may make future advances towards the final eradication of helminth diseases.

The surface of the cuticle of adult Nippostrongylus brasiliensis has been studied by means of the freeze-fracture technique and by transmission electron microscopy. Some of the surface coat appears to have been shed from the surface of the cuticle of adults fixed in situ in the intestine of its host and from the surface of individuals removed from the intestine and freeze-fractured. Freeze-fracturing the cuticle of individuals removed from the host has shown that this surface coat varies in thickness from 30 to 90 nm. The epicuticle is about 20 nm thick and cleaves readily to expose E- and P-faces. The P-face of the epicuticle possesses a small number of particles, similar to intra-membranous particles, whilst the E-face possesses a few, widely scattered depressions. Despite the presence of these particles the epicuticle is not considered to be a true membrane. Freeze-fracturing the remainder of the cuticle has confirmed its structure as described by conventional transmission electron microscopy. Clusters of particles on the P-face of the outer epidermal (hypodermal) membrane and corresponding depressions on the E-face of the membrane are thought to be associated with points of attachment of the cuticle to the epidermis (hypodermis). No differences in appearance of the cuticle and its surface layers were observed in individuals taken from 7-, 10-, 13- and 15-day infections.

Toxocara canis infective larvae are known to produce abundant glycosylated molecules which may be found associated with the surface or secreted into their environment. Using a range of fluorescein-conjugated and gold-conjugated lectins, the localization of particular carbohydrates was defined on the surface of live parasites, and internally at the ultrastructural level. Surface exposure of N-acetyl galactosamine and N-acetyl glucosamine was deduced by binding of FITC-conjugated Helix pomatia (HPA) and wheat-germ agglutinins (WGA). These sugars appear to be associated with a densely staining surface coat as conventional immuno-electron microscopy procedures dissipate this coat and reveal no surface binding site for these lectins. However, by using cryo-immuno-electron microscopical (C-IEM) techniques, the surface coat is retained and can be shown to bind WGA. The fluorescent lectins also revealed strong WGA binding to the secretory and amphidial pores, while the buccal opening and the cuticular alae bound HPA. Corresponding results were obtained at the ultrastructural level. Thus, HPA bound to the electron-dense area of the cuticle, areas of local cuticular thickening such as the alae and buccal labia, as well as to the oesophageal lumen. WGA also bound to the thickened cuticle of the alae and the buccal opening, but showed no reaction to either the electron-dense layer of the cuticle or the oesophageal lumen. Unlike HPA, WGA did bind specifically to the secretory column contents and the electron-dense regions of the lips associated with the chemosensory amphids. The compartmentalization of the sugars N-acetyl galactosamine and N-acetyl glucosamine, their sources and routes of surface expression and the possible association with the TES glycoprotein antigens are discussed.

The cuticle of adult forms of Strongyloides venezuelensis was studied by routine transmission electron microscopy, conventional freeze-fracture and also using quick-freeze and deep-etch techniques. In routine thin sections the cuticle of S. venezuelensis comprises 7 layers: epicuticle, outer cortical, inner corticcal, external medial, internal medial, fibrous and basal. Observation of replicas of specimens fractured across the thickness of the body wall, revealed at the epicuticle an ordered array of particles accompanying the cuticular annulations. At the level of the cortical and medial layers we observed few scattered particles embedded in an amorphous matrix without a particular arrangement. The fibrous layer was represented by several parallel lines of ordered particles of similar size. In tangentially fractured specimens, the epicuticle cleaves readily exposing 2 faces, one exhibiting intramembranous particles without any particular arrangement, immersed in a smooth matrix (P face), and the other showing depressions and very few particles (E face). In replicas of fractures submitted to etching, we observed at the level of the cortical, medial fibrous and basal layers an interconnecting fibrous and globous structure which was organized in a different direction at the fibrous layer. The association of freeze-fracture to deep-etch technique revealed the internal structural organization of the cuticle layers showing details that were not seen before using conventional freeze–fracture technique.

Monoclonal antibody 2A6 binds to the surface of the Dictyocaulus viviparus L3 sheath and identifies a molecule which is highly antigenic in both infected and vaccinated cattle. Immunogold electron microscopy reveals that the antibody binds to a highly stable surface coat overlying the epicuticle of the L3 sheath. The binding to the cuticular surface is stage specific, being restricted to the surface of the L3 sheath, although the antigen can be detected on Western blots of parasite homogenates from the L1 stage. Immunofluorescence on live parasites demonstrates that the antibodies also bind to the L3 sheath surface of many other strongylid nematodes. The antigen detected by 2A6 differs in molecular weight between the species; in D. viviparus the antigen is poorly resolved between 29 and 40 kDa by SDS-PAGE whereas in nematodes from the family Trichostrongyloidea a single band or doublet of approximately 20 kDa is detected, suggesting that a related molecule is present in these species. Although infection and vaccination with D. viviparus elicits a strong immune response to the L3 sheath antigen this does not appear to be the case following infection with other strongylid nematodes.

The cuticle of filarial nematodes is a specialized extracellular matrix that covers the parasite and protects it from adverse conditions of the environment. As a surface structure it is in direct contact with the host defence mechanisms and therefore plays an important role in the molecular host-parasite relationship. Using polyclonal antisera raised against the insoluble components of the cuticle of the adult filarial parasite Brugia pahangi, we have isolated cDNA clones encoding collagen molecules of the cuticle. The protein domain structure of cDNA clone Bpcol-1 was compared with the known structures of cuticular collagens of the nematodes Brugia malayi, Caenorhabditis elegans, Ascaris suum and Haemonchus contortus, confirming interspecies similarities. Using affinity-purified anti-Bpcol-1 antibodies we identified Bpcol-1 antigenic determinants in different nematode extracts, and determined the localization of such epitopes within the cuticle of B. pahangi.

Spores of the bacterium Pasteuria penetrans adhered to second-stage juveniles of both Meloidogyne incognita and M. arenaria, but in standard attachment assays far fewer adhered to the latter species. Similarly, a polyclonal antibody was shown not to recognize the surface coat of M. arenaria but did recognize the surface coat of M. incognita. Although the incubation of whole, intact 2nd-stage juveniles of M. incognita in a series of detergents and protein-denaturing agents at room temperature did not reduce the number of spores adhering after exposure to the bacterium, incubation in buffer (PBS) alone at 100 °C for 2 min did. Immunoblotting of cuticle extracts onto nitrocellulose and probing the blots with antibody showed that the antibody recognized a large protein of Mr 80 kDa and a series of smaller proteins of approximately 43 kDa on M. incognita which were not recognized in extracts from M. arenaria. As incubation of the 2nd-stage juveniles in antibody prohibited spore attachment it is suggested that these proteins may be involved in spore adhesion. Large differences exist between M. incognita and M. arenaria in the amounts of surface-associated proteins on the 2nd-stage juvenile cuticle.

Pasteuria penetrans is a bacterium with the potential to control plant-parasitic nematode populations; the mechanism of spore adhesion, however, is poorly understood. Attachment assays were performed in media supplemented with various concentrations of fibronectin and in the presence and absence of KSCN which modulates hydrophobic interactions. A reduction in the strength of the hydrophobic effect prevented spores from binding to the cuticle as did 20 μg/ml fibronectin. It was also shown directly utilizing a newly-developed technique which utilizes 3-hexadecanoyl-7-hydro-coumarin as an indicator of the fibronectin binding to the spore surface that the presence of KSCN prohibited binding. This effect was interpreted to indicate that the reduction of binding was the direct result of the influence of hydrophobic interactions between the fibronectin and the spore surface. Western blot analysis of cuticle extracts of Meloidogyne incognita and Caenorhabditis elegans revealed small amounts of fibronectin to be present. Fibronectin, or a similar receptor, present in the cuticle could be responsible for the adhesion of P. penetrans by hydrophobic interactions.

Ultrastructural changes associated with exsheathment of the infective juveniles of Haemonchus contortus are described. Hyaline ring formation occurs associated with annulations 10 and 20 and consists of the dissolution of the basal zone and the inner electron-dense layer resulting in the rupture of the sheath. These changes are consistent with the action of a protease-exsheathing enzyme. There is a significant reduction associated with exsheathment in the size of the excretory cells and the number of excretory granules contained within them. No changes in the oesophagus were observed associated with exsheathment. These, and the observations of earlier workers, suggest that it is the excretory cells and not the oesophagus which are the source of exsheathing fluid during exsheathment.

Secretions of plant-parasitic nematodes which are released into plant tissue may play critical roles in plant-nematode interactions. The identification and characterization of these molecules are of fundamental importance and may help to facilitate the development of novel strategies to interfere with nematode infection of plants and thereby decrease nematode-induced damage to crops. An antibody-based approach was used to isolate molecules present on the nematode surface and in nematode secretions. Monoclonal antibodies (MAbs) were produced to secretions and to whole Heterodera avenue 2nd-stage juveniles; several of these MAbs recognized molecules present in nematode secretions produced in vitro. Three of these molecules have been partly characterized in H. avenae, Globodera rostochiensis, G. pallida and Meloidogyne incognita. A MAb reacting with the surfaces of these nematodes recognized antigens of different molecular weight in each of the species tested. This difference in antigenicity might be related to specific functions in these nematodes. Preliminary results show that this antibody also localized the antigen in root cells surrounding the feeding site induced by M. incognita in Arabidopsis thaliana.

The phylogenetic interpretation of the nematode cuticle ultrastructure is reviewed within the framework of recent DNA-sequence data. In particular, the structure of the median and basal zones is discussed. Several structural elements of the cuticle seem to have arisen independently several times within the Nematoda and thus are highly homoplasious (e.g. the cortical or basal radial striae, spiral fibre layers and a fluid matrix with struts). Moreover, identifying the homology of the nematode cuticle ultrastructures is often very difficult at deep taxonomic levels. Hence, the cuticle appears to be unreliable regarding resolution of deep-level relationships in the Nematoda. However, at less inclusive taxonomic levels (e.g. families, genera, …) the cuticle seems to be a more reliable phylogenetic marker.

Quantification of calcium in the cuticle of the fly larva Exeretonevra angustifrons was undertaken at the micron scale using wavelength dispersive X-ray microanalysis, analytical standards, and a full matrix correction. Calcium and phosphorus were found to be present in the exoskeleton in a ratio that indicates amorphous calcium phosphate. This was confirmed through electron diffraction of the calcium-containing tissue. Due to the pragmatic difficulties of measuring light elements, it is not uncommon in the field of entomology to neglect the use of matrix corrections when performing microanalysis of bulk insect specimens. To determine, firstly, whether such a strategy affects the outcome and secondly, which matrix correction is preferable, phi-rho (z) and ZAF matrix corrections were contrasted with each other and without matrix correction. The best estimate of the mineral phase was found to be given by using the phi-rho (z) correction. When no correction was made, the ratio of Ca to P fell outside the range for amorphous calcium phosphate, possibly leading to flawed interpretation of the mineral form when used on its own.