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At least 163 records · Page 9Linked to original sources
PubMed1999

Biomphalaria glabrata embryonic (Bge) cell line supports in vitro miracidial transformation and early larval development of the deer liver fluke, Fascioloides magna.

A Bge cell co-culture system, previously shown to support the in vitro production of daughter sporocysts from mother sporocysts of Schistosoma mansoni and S. japonicum, has proven capable of supporting the in vitro development of intramolluscan stages of the deer liver fluke, Fascioloides magna. Miracidia commenced transforming within 4 h of incubation with Bge cells, and had completely shed their epidermal plates within 18-24 h. Redial stages were visible inside in vitro-transformed mother sporocysts after 12-16 days of co-culture with Bge cells, and emerged as fully-developed larvae starting at 14-20 days post-cultivation. Rediae survived over 60 days of in vitro culture, and reached a maximum size of 150-170 microns. Although particulate material was visible in their cecae, rediae were not observed to actively feed on Bge cells. Bge cells did not attach to or encapsulate larval stages at any time throughout the incubation period. Unlike Schistosoma spp., in which a high percentage of miracidia spontaneously shed their ciliated epidermal plates and transformed into mother sporocysts in Chernin's balanced saline solution (CBSS), transformation of F. magna was dependent on Bge cell products. Less than 5% of F. magna miracidia transformed spontaneously in either CBSS or Bge medium with 10% fetal bovine serum (complete or C-Bge). However, incubation of miracidia in either Bge cell-conditioned C-Bge medium or a greater than 30 kDa fraction concentrated from conditioned CBSS increased transformation rates to 67 and 83%, respectively. This secretory Bge cell factor(s) appeared to be protein in nature since its activity was completely abrogated by heat or proteinase K treatments. Overall, these results demonstrate that Bge cells are required for stimulating in vitro miracidial transformation and supporting early larval development of a fasciolid trematode under culture conditions. This is the first report of in vitro development of rediae from miracidia for a digenetic trematode.

Animals↗
PubMed1995

The morphogenic features of otoconia during larval development of Cynops pyrrhogaster, the Japanese red-bellied newt.

Otoconia are calcified protein matrices within the gravity-sensing organs of the vertebrate vestibular system. Mammalian otoconia are barrel-shaped with triplanar facets at each end. Reptilian otoconia are commonly prismatic or fusiform in shape. Amphibians have all three otoconial morphologies, barrel-shaped otoconia within the utricle, with prismatic and fusiform otoconia in the saccule. Scanning electron microscopy revealed a sequential appearance of all three otoconial morphologies during larval development of the newt, Cynops pyrrhogaster. The first otoconia appear within a single, developing otolith, and some resemble adult barrel-shaped otoconia. As the larvae hatch, around stages 39-42, the single otolith divides into two anatomically separate regions, the utricle and saccule, and both contain otoconia similar to those seen in the single otolith. Throughout development, these otoconia may have variable morphologies, with serrated surfaces, or circumferential striations with either separated facets or adjacent facets in the triplanar end-regions. Small fusiform otoconia occur later, at stage 51, and only in the saccule. Prismatic otoconia appear later still, at stage 55, and again only in the saccule. Thus, although prismatic otoconia are the most numerous in adult newts, it is the last vestibular otoconial morphology to be expressed.

Animals↗
PubMed1990

[Evaluation of larval development of Anopheles darlingi (Diptera-Culicidae) raised in the laboratory on different diets].

Three diets for A. darlingi larvae were tested in order to arrive at the following parameters indicative of development in this phase: length of time, both for overall as for each stage of evolution and daily and total stage-survival. A methodology which combined two vital statistical methods of analysis, adjusted to the study of populations under laboratory conditions, was used for determining these parameters. The length of time for overall and for each stage of, evolution were graphically assessed on the basis of trend curves of colony median stages, in sequential surveys. Values for the total and the daily stage-survival were stimulated from survival tables. Results permitted the selection of the most adequate diet for the larval development as that composed of one part of fish flour to two parts of bread flour and two parts of a heat germ, giving an average length of 12.9 days between the first larval stage and the emergent adult. Total survival rate was of 95%.

Animals↗
PubMed2000

Temperature-dependent regulatory mechanism of larval development of the wax moth (Galleria mellonella).

The mechanisms underlying larval diapause in the wax moth (Galleria mellonella) is one of the most throughly studied aspects. At the low temperature of 18 degrees C, the last instar larvae did not pupate but transferred to 30 degrees C they initiated development and pupation in a circadian manner. Different types of surgical manipulations including head-ligation, nerve cord-severance, implantation of the brain, prothoracic glands, accompanied with ecdysteroid titre measurements indicated that diapausing arrest of larval development at 18 degrees C might be due to the nervous inhibition of their prothoracic glands.

Animals↗
PubMed2006

VHA-8, the E subunit of V-ATPase, is essential for pH homeostasis and larval development in C. elegans.

Vacuolar H+-ATPase (V-ATPase) is an ATP-dependent proton pump, which transports protons across the membrane. It is a multi-protein complex which is composed of at least 13 subunits. The Caenorhabditis elegans vha-8 encodes the E subunit of V-ATPase which is expressed in the hypodermis, intestine and H-shaped excretory cells. VHA-8 is necessary for proper intestinal function likely through its role in cellular acidification of intestinal cells. The null mutants of vha-8 show a larval lethal phenotype indicating that vha-8 is an essential gene for larval development in C. elegans. Interestingly, characteristics of necrotic cell death were observed in the hypodermis and intestine of the arrested larvae suggesting that pH homeostasis via the E subunit of V-ATPase is required for the cell survival in C. elegans.

Amino Acid Sequence↗
PubMed2006

Isolation of Atlantic halibut pituitary hormones by continuous-elution electrophoresis followed by fingerprint identification, and assessment of growth hormone content during larval development.

Continuous-elution electrophoresis (CEE) has been applied to separate putative hormones from adult Atlantic halibut pituitaries. Soluble proteins were separated by size and charge on Model 491 Prep Cell (Bio-Rad), where the homogenate runs through a cylindrical gel, and protein fractions are collected as they elute from the matrix. Protein fractions were assessed by SDS-PAGE and found to contain purified proteins of molecular size from 10 to 33 kDa. Fractions containing proteins with molecular weights of approximately 21, 24, 28 and 32 kDa, were identified as putative growth hormone (GH), prolactin, somatolactin and gonadotropins, respectively. These were analyzed further by mass spectrometry and identified with peptide mass protein fingerprinting. The CEE technique was used successfully for purification of halibut GH with a 5% yield, and appears generally well suited to purify species-specific proteins often needed for research in comparative endocrinology, including immunoassay work. Thus, the GH obtained was subsequently used as standards and iodination label in a homologous radioimmunoassay, applied to analyze GH content through larval development in normally and abnormally metamorphosing larvae. As GH is mainly found in the pituitary, GH contents were analyzed in tissue extracts from the heads only. The pituitary GH content increases proportionally to increased larval weight from first feeding to metamorphic climax. No difference in relative GH content was found between normal and abnormal larvae and it still remains to be established if GH has a direct role in metamorphosis.

Amino Acid Sequence↗
PubMed2005

Comparison of porewater and elutriate bivalve larval development toxicity testing in a sediment quality triad framework.

Concurrent porewater (PW) and elutriate (ELU) toxicity testing using newly fertilized larvae of the bivalve Mytilus galloprovincialis was conducted as part of sediment quality triad (SQT) investigations for urban harbor locations. PW samples were consistently more toxic to bivalve larvae than the corresponding ELU sample, including samples collected from uncontaminated reference locations. Ammonia was identified as the most likely toxic agent. EC(20) and EC(50) values of 0.028 and 0.036mg/L un-ionized N, respectively, were determined for M. galloprovincialis. The limitations of incorporating PW bivalve larval development toxicity tests using M. galloprovincialis for routine SQT investigations, as well as possible alternative methods, are discussed.

Ammonia↗
PubMed2005

Larval development of Neostrongylus linearis (Nematoda, Protostrongylidae) in the mollusc Cochlicella barbara infected and maintained in a subhumid area (north-west Spain) and its possible influence on the infection of small ruminants.

Twelve batches of 100 Cochlicella barbara (Mollusca, Helicidae) were deposited monthly, from January to December in plots (0.5 x 0.5 m) with faeces of sheep containing first-stage larvae of Neostrongylus linearis in order to be naturally infected, and another 12 batches acted as uninfected controls. Every 2 weeks dead molluscs were removed from the plots and three to five specimens were examined to study larval development in the snail. Infected and control snails did not differ in their mortality, which may be associated with the low rate of infection of snails. The highest number of molluscs that were infected and the maximum level of infection were observed in batches deposited in summer months. There was a positive correlation between the percentage of infected snails and temperature. Molluscs harboured higher number of infectious third-stage larvae (L3) from mid-spring to mid-autumn and especially in summer months; thus under these climatic conditions and periods small ruminants are more likely to get infected by N. linearis.

Animals↗
PubMed2006

In vitro activity of Peltophorum africanum Sond. (Fabaceae) extracts on the egg hatching and larval development of the parasitic nematode Trichostrongylus colubriformis.

Trichostrongylus colubriformis is an important cause of parasitic gastroenteritis in ruminants, where it causes protracted diarrhoea, rapid loss of weight, loss of production and death. The in vitro efficacy of extracts of Peltophorum africanum was determined against this parasitic nematode. Eggs and larvae of T. colubriformis were incubated at 23 degrees C in the extracts of the leaf, bark and root of P. africanum at concentrations of 0.008-25 mg ml-1 for 2 and 5 days, respectively. Thiabendazole and water were used as positive and negative controls, respectively. Inhibition of egg hatching and larval development increased significantly (P<0.05) with increasing concentrations of the extracts. Concentrations of 0.2-1.0 mg ml-1 of the extracts of leaf, stem bark, and root bark of P. africanum completely inhibited the hatching of eggs and development of larvae. No eggs and larvae of T. colubriformis could be observed in wells incubated with all the three extracts at concentrations of 5 and 25 mg ml-1. The in vitro model results support the traditional use of P. africanum against nematode parasites. Further research is required to isolate and structurally identify the active anthelmintic compounds, and to improve methods of plant extraction of the effective anthelmintic components that will be readily adaptable for use by rural communities against helminthosis.

Acetone↗
PubMed2005

Cloning of full-length zebrafish dcc and expression analysis during embryonic and early larval development.

Members of the DCC family play key roles in axon guidance in vertebrates as well as invertebrates. In zebrafish, only a short partial sequence of the dcc gene has been reported to date. Here, we report the cloning of full-length zebrafish dcc. Zebrafish DCC shares the typical structure of the DCC subgroup of the immunoglobulin superfamily, consisting of four immunoglobulin and six fibronectin-type III repeats in the extracellular domain, a single transmembrane domain, and an intracellular domain with three conserved motifs. As a first step toward studying the function of dcc, we analyzed its sequence and characterized its expression pattern during embryonic and larval development. dcc is expressed highly in brain and spinal cord, but distinct staining was also observed in developing pectoral fins, pancreas, intestine, and heart. Thus, dcc may play roles not only in axon guidance, but in morphogenesis and functioning of these organs as well.

Amino Acid Sequence↗
PubMed1988

Acidic intracellular pH shift during Caenorhabditis elegans larval development.

During recovery from the developmentally arrested, nonfeeding dauer stage of the nematode Caenorhabditis elegans, metabolic activation is accompanied by a decrease in intracellular pH (pHi). Phosphorus-31 nuclear magnetic resonance (31P NMR) analyses of perchloric acid extracts show that inorganic phosphate predominates in dauer larvae, whereas ATP and other high-energy metabolites are abundant within 6 hr after dauer larvae have been placed in food to initiate development. Although metabolic activation has been associated with an alkaline pHi shift in other organisms, in vivo 31P NMR analysis of recovering dauer larvae shows a pHi decrease from approximately 7.3 to approximately 6.3 within 3 hr after the animals encounter food. This shift occurs before feeding begins, and it coincides with, or soon follows, the developmental commitment to recover from the dauer stage, suggesting that control of pHi may be important in the regulation of larval development in nematodes.

Animals↗
PubMed1995

In situ hybridization analyses of Na, K-ATPase alpha-subunit expression during early larval development of Artemia franciscana.

The spatial pattern of expression of the mRNA encoded by the Na,K-ATPase alpha-subunit cDNA clone pArATNa136 was determined by in situ hybridization of first, second, and third instar Artemia franciscana larvae. This mRNA was expressed at high levels in the salt gland, the antennal gland, and the end of the midgut, which are the three main osmoregulatory organs in Artemia at these stages of development. The pattern of expression was similar at the three stages of development analyzed, although the level of expression increased during development, especially in the salt and antennal glands. The expression of the mRNA coding for another Na, K-ATPase alpha-subunit isoform, the proposed alpha 2-isoform, was also determined and was shown to be limited to the salt gland. These results suggest that the clone pArATNa136 codes for the biochemically defined alpha 1-isoform of the Na,K-ATPase alpha-subunit and reinforce the importance of this isoform in osmoregulation at the three larval stages studied. The alpha 2-isoform may also be involved in osmoregulation during the first stages of larval development.

Animals↗
PubMed1996

Ecdysteroid mediated muscle actin synthesis during the larval development of rice moth, Corcyra cephalonica.

Protein fractions from the whole body homogenates were separated on SDS-PAGE and the muscle actin band was identified by western blotting, using commercial antibody raised against chick back muscle actin (Sigma Chemical Co., USA). The antibody was found to be specific for muscle actin, as it did not cross react with cytoplasmic actin of the nervous system. The molecular weight of the muscle actin in Corcyra was found to be around 46 kDa. The concentration of actin was found to be more or less the same in penultimate and early-last instar larvae and it increased during mid and late-last instar development. Thereafter, it has dropped to its minimum during the pupal stage. But, once again it increased to its maximum in adults. Thorax-ligation in early and late-last instar larvae resulted in decreased synthesis of muscle actin and this was more pronounced after 48 h of ligation. Injection of 20-hydroxyecdysone to insects which were thorax-ligated for 24 and 48 h was found to significantly increase the concentration of actin, suggesting that the ecdysteroids mediate the muscle actin synthesis during the larval development of Corcyra.

Actins↗
PubMed2006

Gene-breaking transposon mutagenesis reveals an essential role for histone H2afza in zebrafish larval development.

We report a novel gene tagging, identification and mutagenicity ('gene-breaking') method for the zebrafish, Danio rerio. This modular approach consists of two distinct and separable molecular cassettes. The first is a gene-finding cassette. In this study, we employed a 3' gene-tagging approach that selectively 'traps' transcripts regardless of expression status, and we show that this cassette identifies both known and novel endogenous transcripts in transgenic zebrafish. The second is a transcriptional termination mutagenicity cassette assembled from a combination of a splice acceptor and polyadenylation signal to disrupt tagged transcripts upon integration into intronic sequence. We identified both novel and conserved loci as linked phenotypic mutations using this gene-breaking strategy, generating molecularly null mutations in both larval lethal and adult viable loci. We show that the Histone 2a family member z (H2afza) variant is essential for larval development through the generation of a lethal locus with a truncation of conserved carboxy-terminal residues in the protein. In principle this gene-breaking strategy is scalable for functional genomics screens and can be used in Sleeping Beauty transposon and other gene delivery systems in the zebrafish.

Animals↗
PubMed1984

Retinal ganglion cell terminals change their projection sites during larval development of Rana pipiens.

Interconnecting neuronal populations in the vertebrate CNS are typically not well matched in their overall topographic patterns of histogenesis and differentiation during development. One striking example of this mismatch is the retinotectal system of the frog, where the retina grows in concentric annuli, while the optic tectum, a major retinal target, adds new neurons at only the caudo-medial border. The retinal ganglion cell (RGC) terminals nevertheless form an organized map in the tectum during the period when the two structures are undergoing such disparate modes of growth. This led Gaze et al. (Gaze, R. M., M. J. Keating, and S. H. Chung (1974) Proc. R. Soc. Lond. (Biol.) 185: 301-330) to propose that the terminals must shift caudally during development. In the present study, we have directly tested the hypothesis of "shifting connections" by selectively labeling an identified population of RGC terminals, those at the optic nerve head (ONH), and determining their tectal projection site relative to a particular group of [3H]thymidine-labeled tectal neurons. With this double-label technique, we have found that RGC terminals from cells at the ONH move from a position rostral to the [3H]thymidine-labeled tectal cells to a position caudal to these same cells during the latter half of larval development. This represents a movement of approximately 1.4 mm across the tectal surface between stages T&K XII and T&K XXV. In addition, we have used electron microscopy and electrophysiology to demonstrate that the RGC terminals make functional synaptic connections during this period. This indicates that RGC terminals continually change the tectal neurons with which they form functional synapses during the development of the retinotectal system. We propose that such moving, but highly ordered connections can best be explained by a two stage mechanism for map formation, in which graded selective adhesions between cells in appropriate regions of retina and tectum provide the overall gross retinotopy of the projection, while competitive interactions between RGC terminals are responsible for the refinement of the precision in this system.

Animals↗
PubMedDate not supplied

Effect of the nematophagous fungus, Duddingtonia flagrans, on the larval development of goat parasitic nematodes: a plot study.

Effective alternatives to anthelmintic treatment against nematode parasites of goats are required because of the high prevalence of benzimidazole resistance. Towards this objective, the nematophagous fungus, Duddingtonia flagrans (Df), was used in a plot study against two main parasitic nematode species of goats, Teladorsagia circumcincta (Tcir) and Trichostrongylus colubriformis (Tcol). Worm-free, culled goats were experimentally infected with strains of Tcir and Tcol to constitute donors. Half of the animals were periodically given Df chlamydospores at a daily dose of 2.5 x 10(5) spores/kg BW while the remaining animals were kept as controls. At 5 time periods i.e. March, May, July, September and November 2001, corresponding to the main grazing season in France for goats, faeces were collected from the 6th day of fungus administration for the following 2 days to obtain approximately 1 kg of faeces from each group of animals: Tcir/Control, Tcol/Control, Tcir/Fungus, Tcol/Fungus. For each period and each group, the faeces were deposited on a 1 m2 grass plot and the grass was cut (3 replicates) on weeks 2, 4, 6, 8,12 after deposition, for infective larval recovery. Larvae were counted and the results were expressed as a ratio of larvae/eggs deposited. On the plots with the control faeces deposited in March, July and September, the grass infectivity due to Tcir and Tcol was similar and the maximum number occurred between 2 and 4 weeks post deposition. In May, the maximum numbers of larvae were not recorded until 8 weeks after deposition, due to high daily temperatures and dryness. In November, larval development took place only for Tcir. On the plots with the fungus treated faeces, a significant reduction in grass infectivity occurred for both nematodes and ranged from 50-60% in May, July and November deposits to 80-90% in the September deposit. On the contrary to these findings, no difference was recorded between the fungus and control plots for the March deposit. In conclusion, D. flagrans is suitable for reducing the number of infective larvae in the herbage during the main part of the grazing period for the most important digestive nematodes of goats.

Animals↗
PubMed1995

Cardiac output and peripheral resistance during larval development in the anuran amphibian Xenopus laevis.

Stroke volume (SV) and cardiac output (CO) were measured in anesthetized larvae of Xenopus laevis from hatching (3 mg) to the end of metamorphosis (approximately 1 g). CO and SV were calculated from videotaped images of the intact beating heart. SV increased from 2.4 x 10(-3) microliters at 3 mg body mass to 7.6 microliters at 1 g. CO increased from 0.25 microliter/min at 3 mg to 623 microliters/min at 1 g. With use of CO, along with arterial pressures from another study [P.-C. L. Hou and W. W. Burggren. Am. J. Physiol. 269 (Regulatory Integrative Comp. Physiol. 38): R1120-R1125, 1995], peripheral resistance and cardiac work were also calculated. Resistance decreased rapidly from 701 peripheral resistance units (PRU, mmHg.s.mm-3) at 3 mg body mass to 79 PRU at 20 mg and gradually declined toward 0.9 PRU at 1 g. Cardiac work increased from 0.06 dyn.mm at 3 mg body mass to 1.27 dyn.mm at 20 mg and then climbed sharply to 717 dyn.mm at 1 g. The general pattern of change in hemodynamic variables (except heart rate) during larval development is similar in Xenopus laevis and chick embryos, suggesting a common pattern for hemodynamic development in vertebrate embryos/larvae.

Animals↗
PubMed1998

Characterization of the C. elegans gap-2 gene encoding a novel Ras-GTPase activating protein and its possible role in larval development.

BACKGROUND: The Ras signalling pathway plays several important roles in the development of the nematode Caenorhabditis elegans. So far, two types of Ras-GTPase activating proteins (Ras-GAPs) have been identified in this organism. To aid the study of the regulation and function of the Ras pathway, we set out to isolate a new GAP gene from C. elegans by transcomplementation of the fission yeast gap1 mutant. RESULTS: We isolated a C. elegans cDNA that encoded a protein which was similar to, but not exactly homologous with mammalian p120 Ras-GAP. This gene, named gap-2, generated at least nine distinct mRNA species through transcription from different promoters and subsequent alternative splicing involving 25 exons. These isoforms were differentially expressed among tissues. A deletion of gap-2 caused no obvious phenotype by itself, but a loss of gap-2 function could suppress larval lethality in both let-23 and let-60 reduction-of-function mutants, in which the Ras activity was lowered. CONCLUSIONS: C. elegans gap-2 encodes a novel Ras-GAP, which is similar to vertebrate p120 but which may constitute a new GAP subfamily. gap-2 mRNA isoforms arise by an unusually extensive variation in initiation sites and associated alternative splicing, and each isoform may play a distinct role in specific tissues. GAP-2 appears to function as a negative regulator of LET-60 Ras during larval development.

Alternative Splicing↗