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Many arthropodes are found in close contact with soil and other material contaminated by mycobacteria. In order to clear up their importance as potential carriers of germs of the MAIS complex (Mycobacterium avium, intracellulare, scrofulaceum), we investigated 835 samples of arthropodes taken from different biotopes. Following a treatment according to the cultural method developed by us (Beerwerth, 1967), we isolated 606 strains of mycobacteria from 302 (36.0%) out of 835 samples. Incubation at room temperature was more effective than incubation at 37 degrees C. 96 (15.8%) in 606 strains did not grow at 37 degrees C. In arthropodes taken from pasture-ground we mainly found mycobacteria of group II according to Runyon, while in arthropodes from arable land, stables and saw mills mycobacteria of group III predominated. Samples of arthropodes taken from forests, moorland and waters showed a comparatively similar spectrum of species. Strains of the MAIS complex - M. avium, intracellulare, scrofulaceum - were frequent in areas of saw mills (80 = 20.5% in 356 strains), but rarely found amongst the remaining biotopes (11 = 4.4% in 250 species). Mycobacteria were chiefly isolated from larvae and imagines living in permanent contact with soil and less from winged shapes. The epidemiological importance of arthropodes spreading pathogenic mycobacteria should not be overvalued.
Insects and other arthropods have bead-like structures in Golgi complexes from all cell types. They are arranged in rings at the base of transition vesicles located near the smooth surface of the rough endoplasmic reticulum making the forming face of the Golgi complex and are only seen easily after staining in bismuth salts. Procedures used to demonstrate the beads in arthropod Golgi complexes do not selectively stain any structures where they would be expected to occur in several mouse and tadpole tissues. However, a faint pattern similar to the arthropod GC beads can be made out in the large GCs concerned in the formation of acrosomes during mouse spermatogenesis. Uranyl staining shows particles of about the same size and spacing as the beads of arthropod GCs. We conclude that vertebrate GCs may have beads that differ from arthropods in their staining properties.
The hemocyanins from molluscs and from arthropods differ in the size of their polypeptide chains. A variety of physical techniques including sodium dodecyl sulfate polyacrylamide gel electrophoresis and column chromatography in sodium dodecyl sulfate and guanidine HCl indicate that the polypeptide chain of mollusc hemocyanin has a molecular weight of 290,000. These results were corroborated by quantitative end group analyses. Several experiments designed to count the number of tryptophan and methionine-containing peptides in the hemocyanin from the whelk Busycon canaliculatum indicate that sequence homology within the polypeptide chain of the mollusc hemocyanins accounts for their large size. Digestion of the native protein with subtilisin produces a 50,000-dalton fragment in high yield which corresponds to one binding site for oxygen. On the other hand, the polypeptide chain molecular weight of lobster hemocyanin is 76,000 to 78,000 and this seems to be a general property of all arthropod hemocyanins. The pigment from lobster consists of two very similar polypeptide chains which are not present in equal amount. Analysis of the cysteine-containing and of the tryptophan-containing tryptic peptides confirms the value of the molecular weight. However, separation of fragments which contain methionine indicates that there is sequence homology withing the polypeptide chain of this protein. It is concluded that the mollusc and arthropod hemocyanins have little structural similarity.
Spirals are often seen in sections transverse to the axes of bumped structures in arthropod cuticle. (Sections through arthropod cornea or exocones yield excellent examples.) As arthropod cuticle has a helicoidal architecture (Bouligand, 1965), it might be expected that the spirals are a simple consequence of that structure. According to a symmetry argument, the spirals thus predicted must be double spirals. In contrast, the observed spirals are usually single. We propose that the single spirals result from an interaction between the microtome knife and the cuticle architecture. The direction of knife travel defines an orientation within the cuticle, subverting the symmetry arguments that require double spirals. Bouligand (1972) presented a model for the interaction of the knife with the cuticle. However, we offer arguments and observations show that Bouligand's model is incorrect. We argue from detailed observations of the single spiral that it is indeed a knifing artifact and that its explanation probably lies within a certain class of models. Two related models based on relative movements of cuticle components are examined via computer techniques.
Arthropoda form the most diversified and multitudinous phyllum of the animal kingdom. In this "arthropod world", the authors give the respective position of the arthropoda: a) detrimental to crops, b) venomous and noxious for human being, but mainly those who are vectors of human diseases, say about a hundred species. Biological, ecological and environmental main features of the most important arthropod vectors of human tropical diseases are reviewed. Various factors acting on the relation between pathological agent and vector and between vector and man are considered. Importance and complexity of entomological surveys are emphasized with, as a consequence, the necessity of specialized medical entomologists to manage them.
Insect declines are of global concern, yet no long-term ecological studies (LTER) have confirmed this trend on islands. This study utilises the first available LTER data on island arthropods, targeting epigeal and canopy species from the Azores Archipelago (Portugal), and covering over 20 years in three distinct sampling events from 30 standard sites. We investigate changes in abundance, biomass, and species richness within native forest arthropod communities, focusing on the proportions of endemic and introduced species, and temporal patterns among single-island endemics and forest-dependent endemics. Results reveal significant temporal variability, but overall abundance, biomass, and species richness remain stable across endemic and native non-endemic taxa. Among the species studied, 28% declined, 17% increased, and 55% showed no significant differences. Exotic invasions and related extinctions appear minimal. Forest-dependent endemic species declined below anticipated levels, suggesting that the extinction debt for these species may be less severe than initially expected. Nonetheless, some forest specialists have declined significantly, and seven species, not seen over 20 years, are considered to be extinct. The three-decade-long conservation of Azorean native forests may have contributed to the stability of some populations, thus these findings underscore the need for continued and enhanced conservation efforts of insular forest-associated diversity.
Intertropical Africa is the first area in the world for the frequency of arthropod born human diseases, such as malaria, trypanosomiasis, viral infections (f.i.yellow fever), various filariasis and chiefly onchocerciasis. Control of arthropod vectors is very important indeed in this area. It requires a closed collaboration between entomologists, biologists, hygienists and tropical physicians. Chemical control is still preponderant but it must be associated, as often as possible, with physical, biological and genetic means of control.
The blood feeding habit, especially among opportunist feeders such as tabanids and Stomoxys is known to result in transmission of diseases for which the vectors are not the obligate or alternate hosts. Thus, mechanical transmission of trypanosomes such as T. vivax can occur in cattle herds outside tsetse fly areas where tabanids are actively feeding. In the case of Yaws, mechanical transmission of the spirochaetes by eye flies (Hippelates pallipes) in the West Indies is thought to be most likely. The spirochaetes remain motile in the pharynx and oesophageal diverticula for several hours but are apparently immobilised in the midgut (Kumm & Turner, 1936). There is apparently no development ofspirochaetes in the fly. They have been shown to pass through houseflies, but in mechanical transmission, biochemical transformation or adaptation of the pathogen is not implied. Virus transmission is common among arthropods and transovarial transmission to succeeding generations is frequent in mites and ticks. Although Yellow Fever virus is not transovarially transmitted by its vector Aedes aegypti, the mosquito only becomes infective some time after ingesting an infected blood meal (Chandler, 1955). Thus, metabolic or biochemical changes or adaptations in the virus or in the vector are in some way implicated, as they must also be in transovarially transmitted viruses. However, the causal relationships between virus infectivity and vector physiology are poorly understood. As with virus infections, those disease organisms possessing a cyclical host/vector relationship will possess a variable infectivity potential which is not necessarily related to the abundance of any of the organisms in the cycle. Clearly, feeding behavior and host preferences of the vector are important in determining the rate and extent of disease transmission, and such parameters can be quantified in epidemiological studies. However, a complete understanding of the factors concerned in cyclical disease transmission also depends on a knowledge of the physiology of the organisms involved, and particularly of the interdependence of their physiologies. The subject is vast, and it is proposed to illustrate the problems involved and the progress made, by reference largely to trypanosome transmission by tsetse flies (Glossina spp.).
It is assumed that "dark channels" determine a permanent dark conductance of the arthropod visual cell membrane. The light stimulus causes a transient opening of "light channels". The ion selectivity of dark channels and light channels is roughly described. Factors influencing the activation of light channels, as membrane energy metabolism, membrane potential and adjusted calcium ion concentration are specified. The mechanism of the action of calcium ions on the conductance of the visual cell membrane is discussed.
Non-junctional intramembranous particle arrays in the form of ridges, bracelets or rectilinear assemblies have been found by freeze-fracturing in the cytoplasmic half or P face of the plasma membrane in a variety of arthropod tissues. These tissues include both excitable cells, nerve and muscle, and such other cells as those from the intestinal tract, the tracheal system and the connective tissue. The intramembranous ridges are short rows of fused particles about 10 nm in diameter; comparable particles comprise the bracelets and the rectilinear aggregates, although the former are of lower profile. In cells sending out cytoplasmic projections during migration and development, for example, axons in embryonic, newly hatched or pupal tissues, tracheoles or fibroblasts, the intramembranous ridges are always aligned parallel to the longitudinal axis of the cellular process. The physiological significance of these may be that they play some role in recognition during development, perhaps by contact guidance. The ridges and rectilinear arrays found in the gut could also be involved in recognition and/or adhesion. In muscle, bead-like ridges are intimately associated with the transverse tubular system and may have a receptor function. Irregular and circular low-profile ridges occur in the tissues of the horseshoe crab, Limulus, and 'bracelet' forms are found in the inner membrane of insect pupal tracheae. The latter may play a part in the initiation and development of small tracheoles.
DNA-based biodiversity surveys result in massive-scale data, including up to millions of species-of which, most are rare. Making the most of such data for inference and prediction requires modeling approaches that can relate species occurrences to environmental and spatial predictors, while incorporating information about their taxonomic or phylogenetic placement. Even if the scalability of joint species distribution models to large communities has greatly advanced, incorporating hundreds of thousands of species has not been feasible to date, leading to compromised analyses. Here we present a 'common to rare transfer learning' (CORAL) approach, based on borrowing information from the common species to enable statistically and computationally efficient modeling of both common and rare species. We illustrate that CORAL leads to much improved prediction and inference in the context of DNA metabarcoding data from Madagascar, comprising 255,188 arthropod species detected in 2,874 samples.
Arthropod central nervous tissue is fixed for 1 hr at 20 C in 8% pure formic acid in 1:1 n-butanol/n-propanol prepared immediately before use (FBP), then washed for 15-30 min in 90% ethanol, and embedded in paraffin wax. Impregnation is by modified Ungewitter techniques in which the silver bath is preceded by mercury/cobalt mordanting, or by modified Holmes' methods following similar mordanting procedures. The methods yield high resolution of axons with minimal background staining, while the staining of neuronal somata is suppressed. They succeed with brains of crustacea and Odonata and other difficult materials. Tissues fixed in FBP are hard and require care in sectioning.
A review of the present means of control of arthropod vectors in which the authors consider:--individual means aimed at the prevention of bites by utilizing clothes, repellents, mosquito nets and insecticide sprays,--collective means which are either physical, biological or chemical. Physical means are specially used for water control either in "peridomestic actions" or in large scale campaign's related to rural or industrial development scheme. Actually biological means are represented only by larvivorous fishes. The chemical control is the most important, its various requisites, and techniques are given.
Insecticides are still nowadays our main way of control of arthropod vectors. Their use raises many important question, resistance of the vectors, toxicity, risks of pollution and costs of spraying campaigns. These various drawbacks are considered with special regard to the problem of resistance its world wide spreading, its mechanisms, its meaning. The various types of toxicity are also detailed.
The increased incidence during the last years of viral hepatitis demands a new approach to the various eventual possibilities of contamination. The author discusses the transmission of serum hepatitis by mosquitoes, especially in warm climates, and the recent results obtained in investigations on the mechanical or biological transmission by haematophage arthropods.
Limulus thin filaments confer calcium sensitivity on calcium-independent myosins and contain in addition to actin and tropomyosin, three troponin components. The molar ratio of actin:tropomyosin:troponin sub-unit T (TN-T): troponin sub-unit C (TN-C) is approximately 7:1:1:1, as in vertebrates, but twice the amount of the troponin sub-unit I (TN-I) may be present. Arthropod troponin binds approximately 1 mole Ca/mol troponin, a significantly smaller amount than bound by vertebrate troponin.