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PubMed2003

Neuronal expression of tachykinin-related peptides and gene transcript during postembryonic development of Drosophila.

The gene Dtk, encoding the prohormone of tachykinin-related peptides (TRPs), has been identified from Drosophila. This gene encodes five putative tachykinin-related peptides (DTK-1 to 5) that share the C-terminal sequence FXGXRamide (where X represents variable residues) as well as an extended peptide (DTK-6) with the C-terminus FVAVRamide). By mass spectrometry (MALDI-TOF-MS), we identified ion signals with masses identical to those of DTK-1 to 5 in specific brain regions. We have analyzed the distribution of the Dtk transcript and peptides, by in situ hybridization and immunocytochemistry during postembryonic development of the central nervous system (CNS) of Drosophila. Antiserum against a cockroach TRP that cross-reacts with the DTKs was used for immunocytochemistry. Expression of transcript and peptides was detected from first to third instar larvae, through metamorphosis to adult flies. Throughout postembryonic development, we were able to follow the strong expression of TRPs in a pair of large descending neurons with cell bodies in the brain. The number of TRP-expressing neuronal cell bodies in the brain and ventral nerve cord increases during larval development. In the early pupa (stage P8), the number of TRP-expressing cell bodies is lower than in the third instar larvae. The number drastically increases during later pupal development, and in the adult fly about 200 TRP-expressing neurons can be seen in the CNS. The continuous expression of TRPs in neurons throughout postembryonic development suggests specific functional roles in both larval and imaginal flies and possibly also in some neurons during pupal development.

Animals↗
PubMed2000

Developmentally and regionally regulated participation of epidermal cells in the formation of collagen lamella of anuran tadpole skin.

We investigated the cellular mechanism of formation of subepidermal thick bundles of collagen (collagen lamella) during larval development of the bullfrog, Rana catesbeiana, using cDNA of alpha1(I) collagen as a probe. The originally bilayered larval epidermis contains basal skein cells and apical cells, and the collagen lamella is directly attached to the basement membrane. The basal skein cells above the collagen lamella and fibroblasts beneath it intensively expressed the alpha1(I) gene. As the skin developed, suprabasal skein cells ceased expression of the gene. Concomitantly, the fibroblasts started to outwardly migrate, penetrated into the lamella and formed connective tissue between the epidermis and the lamella. These fibroblasts intensively expressed the gene. As the connective tissue developed, the basal skein cells ceased to express the gene and were replaced by larval basal cells that did not express the gene. These dynamic changes took place first in a lateral region of the body skin and proceeded to all other regions except the tail. Isolated cultured skein cells expressed the gene and extracellularly deposited its protein as the type I collagen fibrils. Thus, it is concluded that anuran larval epidermal cells can autonomously and intrinsically synthesize type I collagen.

Animals↗
PubMed2004

Identification of 315 genes essential for early zebrafish development.

We completed a large insertional mutagenesis screen in zebrafish to identify genes essential for embryonic and early larval development. We isolated 525 mutants, representing lesions in approximately 390 different genes, and we cloned the majority of these. Here we describe 315 mutants and the corresponding genes. Our data suggest that there are roughly 1,400 embryonic-essential genes in the fish. Thus, we have mutations in approximately 25% of these genes and have cloned approximately 22% of them. Re-screens of our collection to identify mutants with specific developmental defects suggest that approximately 50 genes are essential for the development of some individual organs or cell types. Seventy-two percent of the embryonic-essential fish genes have homologues in yeast, 93% have homologues in invertebrates (fly or worm), and 99% have homologues in human. Yeast and worm orthologues of genes that are essential for early zebrafish development have a strong tendency to be essential for viability in yeast and for embryonic development in the worm. Thus, the trait of being a genetically essential gene is conserved in evolution. This mutant collection should be a valuable resource for diverse studies of cell and developmental biology.

Animals↗
PubMed1991

Spatial distribution of posttranslationally modified tubulins in polarized cells of developing Artemia.

In many differentiated cells, posttranslationally modified tubulins exhibit restricted subcellular distribution, leading to the proposal that they are required for the production and maintenance of polarity. To study this possibility, we used immunological approaches to examine tubulin isoforms in developing Artemia larvae and to determine their location in several types of cells within the organism. The amount of tubulin in relation to total protein remained relatively constant during early larval development while detyrosinated tubulin increased, an event correlated with the differentiation of larval gut muscle cells. Except for epidermal cells of the developing thorax, each type of cell within the Artemia larvae exhibited characteristic staining patterns which were very similar for each antitubulin antibody. Within epidermal cells, microtubules containing acetylated tubulin appeared patchy or punctate in their distribution, an image not seen with the other antibodies. In most polarized cells, staining for tubulin and actin colocalized in discrete areas, demonstrating enrichment of both proteins within the same cellular compartment and suggesting functional interactions. Mitotic figures were stained with qualitatively equal intensity by all of the antitubulin antibodies, but asters were not observed. Midbodies were intensely stained with phalloidin as well as the antibodies to tubulin. It was clear that microtubules exhibited a preferential localization in cells of Artemia but in no case was a tubulin isoform found exclusively in one area of a cell. The results support the contention that microtubules influence the organization of polarized cell structure and function but they do not permit the conclusion that this capability is dependent on the localization of posttranslationally modified tubulins to restricted subcellular positions.

Actins↗
PubMed2004

Ovipositional response, developmental effects and toxicity of hexavalent chromium to Megaselia scalaris, a terrestrial detritivore.

The effects of hexavalent chromium (Cr VI) on ovipositional response, development, and survival of a common terrestrial detritivore, Megaselia scalaris (Diptera: Phoridae), were assessed in the laboratory. Ovipositing females did not discriminate between substrates containing 0, 50, 500, or 1000 microg/g, indicating a lack of avoidance behavior. Eggs placed on artificial diets containing up to 1000 microg/g either did not absorb Cr VI or were unaffected as measured by eclosion rates. However, development and survival of larvae were significantly reduced at the higher concentrations tested. Concentrations of 500 microg/g in their food increased larval development times by nearly 65%. At 1000 microg/g, larval developmental times doubled. The time required from onset to completion of pupariation was not significantly different regardless of Cr VI concentration. Although males eclosed before females, there was no significant difference between the sexes in the time required for adult eclosion. In addition, there were no significant differences in the percentage of males and females emerging from any of the treatments. At concentrations of 500 or 1000 microg/g, Cr VI decreased larval survival. Survival was reduced by 44.3% at 500 microg/g as compared with the controls. There was no additional mortality from the onset of the puparial stage to adult eclosion for larvae fed diets containing 500 microg/g Cr VI. At 1000 microg/g Cr VI, larval survival decreased by 86.6%. An additional 7.4% mortality was recorded in the puparial stage, for a decrease in total survival (larval plus puparial stages) of 94%. Thus, nearly all of the observed mortality occurred during the larval stage rather than the puparial stage. The population level implications of lack of avoidance of contaminated food and the effects of increased developmental times and reduced survivorship are discussed.

Animals↗
PubMedDate not supplied

Enhanced development in nature of larval Anopheles arabiensis mosquitoes feeding on maize pollen.

To determine whether pollen produced by maize (Zea m. mays) may contribute to the development of larval Anopheles gambiae complex mosquitoes, the main African vectors of malaria, we correlated duration of larval development, pupation success, and size of the resulting adults with degree of access to this potential nutriment. Maize pollen is abundant during the wet season on the surface of water near maize plantings in a malaria-endemic region of Ethiopia, and larval Anopheles arabiensis readily ingest these particles in nature. Larvae develop to the pupal stage more rapidly, more frequently, and produce larger adults where maize pollen is abundant than do those that have little access to this food. The force of transmission of malaria in sub-Saharan Africa might be reduced if maize plantings were excluded from the immediate vicinity of homes or, perhaps, if pollen of such maize were to express entomotoxins.

Animals↗
PubMed1990

Patterns of appearance of serotonin and proctolin immunoreactivities in the developing nervous system of the American lobster.

Serotonin (5-HT) and proctolin, neurohormones widely distributed in the lobster nervous system, have been implicated in a variety of behaviors and also are known to coexist in large pairs of identified neurons in the fifth thoracic (T5) and first abdominal ganglia (A1) of adults (Siwicki, Beltz, and Kravitz, 1987). Earlier studies also have shown that these paired neurons already contain 5-HT in embryos approximately halfway through development, whereas proctolin immunoreactivity does not appear in these cells until near the time of hatching (Beltz and Kravitz, 1987a). In the current studies, the brain and ventral nerve cord have been screened for the appearance of serotonin and proctolin immunoreactivities using immunocytochemical and biochemical methods, in order to determine whether the late appearance of proctolin in the paired T5 and A1 cells is a general feature of development in other neurons as well. In embryos approximately halfway through development, the adult complement of 5-HT-staining cells is already present. In several cases, embryonic serotonin cells are proportionally very large and prominent, suggesting possible developmental roles. In contrast to serotonin, fewer than 10% of the proctolin-staining neurons of juvenile animals are seen in embryos halfway through development. The number of immunoreactive cells gradually increases, but even by the sixth larval stage only half the number of cells that will eventually stain for proctolin are observed. Therefore, the developmental appearance of proctolin in lobster neurons, assayed using immunocytochemical methods, is relatively late and protracted compared to the appearance of serotonin. Quantitative measurements for 5-HT in lobster larvae were performed using high pressure liquid chromatography (HPLC) with dual electrochemical detection and for proctolin using radioimmunoassay. A gradual, probably growth-related increase in the amounts of serotonin and proctolin were seen during larval development. The implications of the biochemical data, in light of the immunocytochemical studies, are discussed.

Animals↗
PubMed1995

Evolution of the fibropellin gene family and patterns of fibropellin gene expression in sea urchin phylogeny.

This study documents evolutionary modifications in the expression patterns of the sea urchin EGF I and EGF III genes, which encode a family of extracellular matrix proteins, the fibropellins. We show that the sea urchin apical lamina, a macromolecular extracellular matrix that surrounds the sea urchin embryo and is made up of the fibropellins, has been conserved through at least 250 million years of echinoid evolution. The contribution of different fibropellin family members to this structure has, however, changed over the course of sea urchin phylogeny, and between two congeneric species that exhibit different developmental modes. Mapping the evolutionary history of the EGF genes on a cladogram of relationships among sea urchins reveals that EGF I is present in all echinoids examined, while EGF III appears to have arisen by duplication and divergence from EGF I during the radiation of a suborder of the camarodont sea urchins some 35-45 million years ago. Alterations in the temporal expression patterns of these genes as well as the loss of one of the two EGF I transcripts and encoded protein are coincident with the evolution of a direct-developing larval form in Heliocidaris erythrogramma. H. erythrogramma and its congener Heliocidaris tuberculata, which develops via a typical echinopluteus larva, shared a common ancestor about 10 million years ago. The differences in fibropellin representation within the apical lamina of the various taxa indicate that a homologous embryonic structure can undergo substantial changes in composition during its evolutionary history.

Animals↗
PubMed2006

Cardiac development in crayfish: ontogeny of cardiac physiology and aerobic metabolism in the red swamp crayfish Procambarus clarkii.

The cardiovascular system performs key physiological functions even as it develops and grows. The ontogeny of cardiac physiology was studied throughout embryonic and larval development in the red swamp crayfish Procambarus clarkii using videomicroscopic dimensional analysis. The heart begins to contract by day 13 of development (at 25 degrees C, 20 kPa O2). Prior to eclosion, heart rate (fH) decreases significantly. Previous data suggests that the decrease in cardiac parameters prior to hatching may be due to an oxygen limitation of the embryo. Throughout development, metabolizing mass and embryonic oxygen consumption primarily increased while egg surface area remains constant. The limited area for gas exchange of the egg membrane, in combination with the increasing oxygen demand of the embryo could result in an inadequate diffusive supply of oxygen to developing tissues. To determine if the decrease in cardiac function was the result of an internal hypoxia experienced during late embryonic development, early and late stage embryos were exposed to hyperoxic water (PO2 = 40 kPa O2). The fH in late stage embryos increased significantly over control values when exposed to hyperoxic water suggesting that the suppression in cardiac function observed in late stage embryos is likely due to a limited oxygen supply.

Aerobiosis↗
PubMed1997

Development and organization of the retinal dopaminergic system of Ichthyophis kohtaoensis (Amphibia; Gymnophiona).

Ichthyophis kohtaoensis, a member of the limbless Gymnophiona, has a specialized subterranean burrowing mode of life and a predominantly olfactory-guided orientation. The only visually guided behavior seems to be negative phototaxis. As these animals possess extremely small eyes (only 540 microm in diameter in adults), functional investigations of single retinal cells by electrophysiological methods have so far failed. Therefore, the content and distribution of retinal transmitters have been investigated as indications for a functioning sense organ in an animal that is supposed to be blind. In this study, the organization and development of the dopaminergic system have been examined in the retinae of embryonic, larval, and adult I. kohtaoensis, by using an antiserum against tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine synthetic pathway, and an antiserum against dopamine itself. Labeled somata are situated in the inner nuclear layer and in the ganglion cell layer. Dopamine-positive fibers form a dense diffuse plexus, that covers the whole inner plexiform layer, whereas tyrosine hydroxylase-immunoreactive processes show a tendency to arborize in a stratified manner. Tyrosine-hydroxylase-immunolabeled fibers can occasionally be observed in the optic nerve head of larval stages. During ontogenesis and larval development, the distribution of transmitter-expressing cells changes and their number decreases, but no general degeneration of the visual system is detectable. Adult Ichthyophis still have retinal transmitters, indicating that the eyes, although obviously playing a minor role in a subterranean ecological niche, retain all the elements of functioning sense organs.

Amphibians↗
PubMed1998

Development of an indicator to evaluate the impact, on a community-based Aedes aegypti control intervention, of improved cleaning of water-storage containers by householders.

Householders in a community-based programme to control dengue in El Progreso, Honduras, are being encouraged to improve the cleaning of the water-storage containers in which many of the vectors thrive. The objective of the present study was to develop an indicator of the change occurring in human behaviour. Traditional Aedes aegypti larval indices do not differentiate between containers in which all the immature stages are present and those which hold only first- and second-instar larvae. However, it is not essential to prevent all larval development to limit transmission of pathogens by the adults; if the Ae. aegypti in the containers only manage to develop to young larvae before the containers are cleaned, then control of the vector in these containers will be effective. In field trials, sampling of third- and fourth-instar larvae in washbasins by taking five dips (quick immersions to a standard depth) with a hand-held net was found to be sufficient for estimating the true population size of that same cohort. This sampling method was then included in a large-scale survey of households, conducted for programme monitoring. An index was then developed as a summary measure of the degree of infestation of a washbasin by Ae. aegypti. This index was the sum of four variables assessed in the survey: presence of any immature stages (larvae and/or pupae); presence of pupae; detection of third-fourth-instar larvae in a five-dip sample; and a log-transformation of the number of larvae recovered. Based on this new index, the 884 washbasins encountered in the survey were classified as infestation-free (76.2%), or with low-(6.7%), medium-(14.9%) or high-level (2.2%) infestation. Application of the same procedure to 240 drums encountered in the survey showed that 66.3% were infestation-free and 9.2%, 17.1% and 7.4% had low-, medium- and high-level infestations, respectively. Compared with the traditional indices, this new index should be more sensitive to changes in human behaviour resulting from a control programme exposure than a simple, dichotomous variable (i.e. positive/negative for presence of immature stages). The use of such an index could make the control programme more efficient, allowing the greatest efforts to be targeted at households that have medium-high levels of infestation.

Aedes↗
PubMed2005

Multidrug resistance-associated protein MRP-1 regulates dauer diapause by its export activity in Caenorhabditis elegans.

Multidrug resistance-associated proteins (MRPs), when overexpressed, confer drug resistance to cancer cells by exporting anti-cancer agents through the cell membrane, but their role in animal development has not been elucidated. Here we show that an MRP homolog regulates larval development in the nematode Caenorhabditis elegans. C. elegans forms a special third-stage larva called a dauer larva under conditions inappropriate for growth. By contrast, we found that mutants in mrp-1, an MRP homolog gene, form dauer larvae even under conditions appropriate for growth, in the background of certain mutations that partially block the insulin signaling pathway. A functional mrp-1::GFP gene was shown to be expressed in many tissues, and the wild-type mrp-1 gene must be expressed in multiple tissues for a wild-type phenotype. Human MRP1 could substitute for C. elegans MRP-1 in dauer larva regulation, and an inhibitor of the human MRP1 transport activity impaired this function, showing that export activity is required for normal dauer larva regulation. Epistasis studies revealed that MRP-1 acts in neither the TGF-beta nor the cGMP signaling pathway. mrp-1 mutations enhanced the dauer-constitutive phenotype of mutants in the insulin signaling pathway more strongly than that in other pathways. Thus, MRP-1, through its export activity, supports the induction of the normal (non-dauer) life cycle by the insulin signaling pathway.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Laboratory and field studies on oribatid mites as intermediate host of Moniezia expansa infecting Egytptian sheep.

Three species of oribatid mites, Scheloribates zaherii, Zygoribatula tadrosi and Z. sayedi from pure colonies were experimentally exposed to infection by allowing them to feed on stool sheep infected with Moniezia expansa. The mites were followed up to the development of the infective cysticercoids. M. expansa was able to achieve sucessfully its larval development in the three species of oribatid mites under laboratory conditions. These were demonstrated after 84, 73 & 69 days post infection, respectively. Z. tadrosi is recorded as inter-mediate host for the first time in Egypt. Six species of oribatid mites, Oppiella nova, S. laevigatus, S. zaherii, Xylobates souchiensis, Epilohmannia pallida aegyptiaca and Z. sayedi, recovered from the sheep infested farm soil, were found naturally infected with different developmental stages of M. expansa.

Animals↗
PubMed2006

Field infestation, life history and demographic parameters of the fruit fly Bactrocera invadens (Diptera: Tephritidae) in Africa.

Field infestation rates of an invasive fruit fly species, Bactrocera invadens Drew Tsuruta & White on mango was determined at different localities in Kenya. At most of the locations and especially at low elevations, B. invadens frequently shared the same fruit with the indigenous fruit fly species Ceratitis cosyra (Walker) but often occurred at higher numbers than C. cosyra. The level of infestation varied with location ranging from 3.0 to 97.2 flies per kg of fruit. There was a significant inverse relationship between numbers of flies per kg of fruit and elevation at which fruit was collected, suggesting that B. invadens is a predominantly lowland pest. On an artificial diet, development of B. invadens immatures lasted 25 days; egg incubation required 1.2 days, larval development 11.1 days and puparia-adult development 12.4 days. About 55% of eggs developed to the adult stage. Life expectancy at pupal eclosion was 75.1 days in females and 86.4 days in males. Average net fecundity and net fertility were 794.6 and 608.1 eggs, respectively, while average daily oviposition was 18.2 eggs. Daily population increase was 11% and mean generation time was 31 days. Results are discussed in relation to the biology and ecology of the insect and in the development of mass rearing and control measures for B. invadens.

Animals↗
PubMedDate not supplied

[Effect of air temperature and relative humidity on the preimaginal development of Ctenophthalmus teres fleas (Siphonaptera)].

The duration of the development and survival of preimaginal stages of fleas at a temperature of 5 to 30 degrees and relative humidity of 60 to 90% was studied. Minimal average duration of the development an the highest survival rate at all stages were registered at a temperature of 20 to 25 degrees and humidity of 85 to 90%. Under these conditions the whole cycle from egg to image lasts on an average 23 days. The threshold of the development for different stages falls within the limits of 3 to 6 degrees. The duration of the development of all stages was distinctly affected by temperature while the duration of larval development was affected as well by humidity. The survival of larvae was found to be affected by humidity while the survival of individuals in cocoons was considerably affected by temperature.

Animals↗
PubMed2002

Leaf litter decay process and the growth performance of Aedes albopictus larvae (Diptera: Culicidae).

Larvae of the mosquito Ae. albopictus typically develop in small aquatic sites such as tree holes and artificial containers. Organic detritus, in particular decaying leaves, is therefore their major carbon source. Here we demonstrate the importance of leaf characteristics, and in particular their rates of decay, in determining the development and survivorship of larvae. We compared the effects of a rapidly decaying leaf, the maple Acer buergerianum (Angiospermae: Aceraceae) and a slowly decaying leaf, the camphor Cinnamomum japonicum (Angiospermae: Lauraceae), on the larval development of Ae. albopictus at different larval densities in laboratory microcosms. Overall, the maple leaves provided a better substrate and the observed growth patterns could be explained on the basis of a difference in nutritive and chemical contents of the two leaf types. At the highest population density, the duration of the larval period was much shorter in maple litter microcosms. Larval mortality gradually increased with population density in the camphor treatment. In contrast in the rapidly decaying leaf litter microcosms, mortality remained low even as densities increased. Mean pupal size was greater in the individuals fed on the rapidly decaying leaf litter as well as at lower density. Size is likely to be correlated with fitness in the field. In general, rapidly decaying leaf litter will favor mosquito growth resulting in quicker development and higher population sizes. This work emphasizes the importance of the local environment on the development of vector mosquitoes and has important implications for control.

Aedes↗
PubMed2002

Digestive proteases during development of larvae of red palm weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Curculionidae).

The evolution of digestive proteases during larval development of Rhynchophorus ferrugineus (Olivier, 1790) has been studied. A progressive increase of protease activity has been found. The optimum pH for proteolytic activity against azocasein was determined. Caseinograms revealed an active complex of alkaline proteases from the early stages of the development. From the apparent molecular masses, three groups of proteases have been found - high molecular-mass proteases, medium molecular-mass proteases, and low molecular-mass proteases. Studies using specific protease inhibitors showed the major presence of serine proteases in gut extracts. The results obtained from larvae reared on different substrates have made possible a comparative assessment of the influence of diet on the development of the digestive enzymatic system. Larvae fed on an artificial diet showed a complete pattern of digestive proteases. Data suggest that this diet seems to be suitable for future research with this insect pest.

Animals↗
PubMed2001

Correlating differences in larval survival and development of bollworm (Lepidoptera: Noctuidae) and fall armyworm (Lepidoptera: Noctuidae) to differential expression of Cry1A(c) delta-endotoxin in various plant parts among commercial cultivars of transgenic Bacillus thuringiensis cotton.

Differences in larval survival and development of bollworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith), respectively, were found to exist among commercially available Cry1A(c) transgenic Bacillus thuringiensis Berliner (Bt) varieties. Using a quantification assay (ELISA) to measure the levels of delta-endotoxin in two of these varieties ('DP 451B/RR' and 'NuCOTN 33B'), differences in the amount of delta-endotoxin present in various plant parts was correlated with larval survival of bollworms and larval development of fall armyworms throughout the growing season. Larvae that were fed on DP 451B/RR completed development faster and exhibited better survivorship than those larvae fed NuCOTN 33B, whereas lower levels of delta-endotoxin were generally detected in plant parts from DP 451B/RR compared with NuCOTN 33B. These differences may impact population dynamics of these pests which may be a critical factor in managing resistance to Bt. Furthermore, the utility of using this system for providing information to the grower concerning varietal choices may be more common in the future.

Animals↗