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PubMed1996

Sternopleural is a regulatory mutation of wingless with both dominant and recessive effects on larval development of Drosophila melanogaster.

The Drosophila wingless (wg) gene encodes a secreted signaling protein that is required for many separate patterning events in both embryonic and larval development. wg functions in the development of the adult structures have been studied using the conditional mutant wgts and also using regulatory mutations of wg that reduce larval functions. Here we present evidence that Sternopleural (Sp) is another regulatory allele of wg that affects a subset of larval functions. Sp has both a recessive loss-of-function component and a gain-of-function component. The loss-of-function component reflects a reduction of wg activity in the notum and in the antenna. The gain-of-function component apparently leads to ectopic wg activity in the dorsal first and second leg disc and thereby generates the dominant Sp phenotype. Sp and other wg alleles show a complex pattern of complementation. We present evidence that these genetic properties are due to transvection. These results have implications for the genetic definition of a null allele at loci subject to transvection.

Alleles↗
PubMed2001

An assessment of the feasibility of using image analysis in the oyster embryo-larval development test.

In this study the feasibility of using the latest image capture, processing, and analysis techniques in the oyster embryo-larval development (OEL) test was assessed. This initially involved determining whether the OEL test could be carried out in multiwell plates (which would assist in the application of the image analysis technique), based on data from tests with the reference toxicant zinc and industrial effluents. The study then ascertained which of the 31 image analysis parameters of the Image Pro Plus software used was most appropriate for differentiating between the D larvae and non-D larvae at the end of the test procedure in a manner similar to that of visual observations. On the basis of the zinc reference toxicant and effluent test data derived in this study, the OEL test can be effectively carried out in 24 chamber multiwell plates, which provides the opportunity to count objects with image analysis software. The use of the image analysis parameters area and size (length) in combination resulted in mean control abnormalities and EC50 values in zinc reference toxicant tests which were not significantly different statistically from corresponding values derived using visual observations. Discrimination using the area and length parameters may be improved by the inclusion of other parameters in a suite of measurements which would reduce interference from extraneous material or lighting artefacts. Furthermore, the use of multiwell plates and image analysis can eliminate the variability associated with sub-sampling and inter-operator differences in the counts of D larvae and non-D larvae which is evident with the current visual observation method.

Animals↗
PubMed2001

The vascular anatomy of the developing zebrafish: an atlas of embryonic and early larval development.

We have used confocal microangiography to examine and describe the vascular anatomy of the developing zebrafish, Danio rerio. This method and the profound optical clarity of zebrafish embryos make it possible to view the entire developing vasculature with unprecedented resolution. A staged series of three-dimensional images of the vascular system were collected beginning shortly after the onset of circulation at 1 day postfertilization through early- to midlarval stages at approximately 7 days postfertilization. Blood vessels in every region of the animal were imaged at each stage, and detailed "wiring patterns" were derived describing the interconnections between every major vessel. We present an overview of these data here in this paper and in an accompanying Web site "The interactive atlas of zebrafish vascular anatomy" online at (http://eclipse.nichd.nih.gov/nichd/lmg/redirect.html). We find a highly dynamic but also highly stereotypic pattern of vascular connections, with different sets of primitive embryonic vessels severing connections and rewiring in new configurations according to a reproducible plan. We also find that despite variation in the details of the vascular anatomy, the basic vascular plan of the developing zebrafish shows strong similarity to that of other vertebrates. This atlas will provide an invaluable foundation for future genetic and experimental studies of vascular development in the zebrafish.

Angiography↗
PubMed1983

Changes of pancreatic beta cell population during larval development of Rana pipiens.

The morphology and population size of immunohistochemically stained insulin-containing pancreatic beta cells are studied in Rana pipiens during larval development. These beta cells appear as single cells or form small clusters at early stages and gradually develop into large clusters arranged in cords surrounding the blood sinusoids in midlarval stages. The total quantity of these cells increases from stage II through midlarval stages, reaching maximum at stages XVIII and XIX. A significant decrease of total beta cell quantity is observed between stages XIX and XX. This decrease occurs slightly later than the onset of degeneration of exocrine tissue. Morphological indication of beta cell breakdown is also observed during this period. Although the population size of beta cells stays relatively constant from stages XXI to XXV, a further maturational change is observed in beta cell morphology between stages XXIV and XXV. During these stages, the polarization of stained immunoreactivity toward sinusoids is more obvious and there is a general decrease of staining intensity in the cytoplasm.

Animals↗
PubMed2005

Larval development assay for detection of anthelmintic resistance in cyathostomins of Swedish horses.

The aim of this study was to investigate the suitability of a larval development assay (LDA) for the determination of anthelmintic resistance in cyathostomin nematode populations of the horse. In addition, comparison of results between geographic regions, types of horse establishment, and the use of anthelmintics in Sweden, was established. Seventy horse herds from different parts of Sweden were sampled, and strongyle eggs from the faeces of 54 of those were investigated by an LDA (DrenchRite). The following anthelmintics were tested: thiabendazole (TBZ), levamisole (LEV), ivermectin monosaccharide (IVM-MS), ivermectin aglycone (IVM-AG) and pyrantel (PYR). The LC50 values for TBZ and LEV were generally lower than those previously reported in other LDA studies on horse nematodes. This could be related to the infrequent use of these compounds for the past 20 years in Sweden. In this study, there was a great variation within and between assay plates that could not be explained. Still the LC50 values differed significantly between the regions for all anthelmintics, except for pyrantel. The highest LC50s were observed in parasite populations from the south of Sweden. There were no significant differences between riding schools and studs. Limitations of this technique exist, namely the lack of established cut-off values for susceptible and resistant populations and interpretation problems related to multi-species infections. Although there are advantages with LDA such as the possibility of testing several compounds simultaneously without interference with the deworming programmes on the farms, we conclude that LDA currently is not a reliable alternative to the faecal egg count reduction test (FECRT).

Animals↗
PubMed1978

Purification and properties of a ribonuclease induced during the early larval development of Artemia salina.

Dormant gastrulae and developing embryos of the brine shrimp Artemia salina contain very low levels of nuclease activity. During early larval development, there is an induction of ribonuclease which has been partially purified and characterized. The enzyme catalyzes an endonucleolytic cleavage of RNA and has no detectable activity on native or denatured DNA. Among a series of synthetic polynucleotides, poly(U) is hydrolyzed with the highest efficiency and poly(G) is not cleaved by the enzyme. The activity on poly(U) is 100 times higher than on RNA. The enzyme requires Mg2+ or Mn2+ and in inactivated by treatment with chelating agent. The inactive preparations can be reactivated by Ca2+ and Mn2+ but not by Mg2+. The ribonuclease is thermosensitive and has maximal activity at pH 7.5. These properties distinguish the Artemia salina ribonuclease from other eukaryotic ribonucleases already reported. The high activity and specificity of this ribonuclease on poly(U) may suggest a role for this enzyme in the processing of the messenger RNA.

Animals↗
PubMed2004

A novel nuclear receptor/coregulator complex controls C. elegans lipid metabolism, larval development, and aging.

Environmental cues transduced by an endocrine network converge on Caenorhabditis elegans nuclear receptor DAF-12 to mediate arrest at dauer diapause or continuous larval development. In adults, DAF-12 selects long-lived or short-lived modes. How these organismal choices are molecularly specified is unknown. Here we show that coregulator DIN-1 and DAF-12 physically and genetically interact to instruct organismal fates. Homologous to human corepressor SHARP, DIN-1 comes in long (L) and short (S) isoforms, which are nuclear localized but have distinct functions. DIN-1L has embryonic and larval developmental roles. DIN-1S, along with DAF-12, regulates lipid metabolism, larval stage-specific programs, diapause, and longevity. Epistasis experiments reveal that din-1S acts in the dauer pathways downstream of lipophilic hormone, insulin/IGF, and TGFbeta signaling, the same point as daf-12. We propose that the DIN-1S/DAF-12 complex serves as a molecular switch that implements slow life history alternatives in response to diminished hormonal signals.

Aging↗
PubMed1975

Influence on allograft rejection of thymectomy at different stages of larval development in urodele amphibian Pleurodeles waltlii Michah. (Salamandridae).

Thymectomy was performed on the urodele amphibian Pleurodeles waltlii Michah. from the 5th to the 20th week of larval development. Thymectomized animals were allografted at 7 months of age. The results obtained are as follows: (1) Pleurodeles thymectomized before 10 weeks always tolerated allografts: (2) Pleurodeles thymectomized within 11 to 13 weeks generally rejected allografts in a chronic manner, but sometimes tolerated them; (3) normal rejections occurred in Pleurodeles thymectomized at 14 weeks, or later. Stage 52 of the developmental table (10 weeks of age) is a critical "end stage" for the efficiency of thymectomy. The results are confirmed by the fate of second set allografts performed in all these animals.

Age Factors↗
PubMed1988

The life cycle and larval development of Fibricola seoulensis (Trematoda: Diplostomatidae).

The life cycle of Fibricola seoulensis was studied in the laboratory and in the field, with special interests in the larval developments within the eggs and in the intermediate hosts. The first emergence of miracidia after incubation of eggs in 26C water began on the ninth day. The miracidia, elongate and cylindrical shape, had epidermal plates in the formula of 6, 9, 4 and 3, with two pairs of flame cells and lateral processes. A kind of fresh water snail, Hippeutis (H.) cantori, was found to shed furcocercous cercariae from the 13th day after experimental challenge with miracidia while Physa acuta failed to shed. The same kind of snail collected from the field also shed the same cercariae. The cercariae were equipped with 2 pairs of penetration glands and 5 pairs of flame cells. The tadpoles of Rana nigromaculata were found susceptible to experimental infection with the cercariae. The same kind of tadpoles collected from various areas were also found naturally infected. The metacercariae in the tadpoles which were infected experimentally became infective to the definitive host in 21 days. The metacercariae were located free in the body cavity of tadpoles, and attained sexual maturity in rats in 7 days. The present study successfully followed the complete life cycle of F. seoulenis and found that it is possible to maintain the life cycle in the laboratory.

Journal Article↗
PubMed2005

Cloning of the growth hormone cDNA of alligator gar Atractosteus spatula and its expression through larval development.

The alligator gar (Atractosteus spatula) is the largest freshwater fish inhabiting rivers draining into the Gulf of Mexico. This primitive fish shows a fast growth rate since its early larval stages. This is attributed to the action of growth hormone (GH), an anterior pituitary gland hormone responsible for linear growth in vertebrates that can also be expressed in extrapituitary adult tissues and in fish embryos. The present research was aimed at obtaining the GH coding sequence of the alligator gar and studying its expression through larval development. A cDNA was obtained by RT-PCR, cloned and sequenced. The alligator gar GH cDNA sequence shares 98% nucleotide similarity with that reported for Lepisosteus osseus, indicating a very slow evolution of the GH within the primitive fish, in contrast with the burst of changes observed in euteleosts. Using RT-PCR and RNA nuclease protection assays, GH transcripts were detected at very high levels in eggs, embryos and in several larval stages. These data suggest that the GH may play an important role during embryogenesis in fish. The better understanding of alligator gar larval physiology will facilitate the culture of larvae and juvenile gar and consequently may allow the restoration of their natural populations.

Alligators and Crocodiles↗
PubMed2005

Larval development and post-settlement metamorphosis of the barnacle Balanus albicostatus Pilsbry and the serpulid polychaete Pomatoleios kraussii Baird: Impact of a commonly used antifouling biocide, Irgarol 1051.

AbstractThe impact of a commonly-used antifouling algicide, Irgarol 1051, on the larval development and post-settlement metamorphosis of the barnacle, Balanus albicostatus Pilsbry (Crustacea: Cirripedia), and the larval metamorphosis of a serpulid polycheate, Pomatoleios kraussii Baird, was evaluated. In the case of B. albicostatus, larval mortality increased with an increase in the concentration of Irgarol 1051, and there was a shift in the larval stage targeted from advanced instars to early instars. Nauplii that survived to the cyprid instar stage when reared in the presence of Irgarol 1051 showed prolonged instar and total naupliar duration when compared to the controls. The post-settlement metamorphosis of cyprids significantly varied with Irgarol concentration and also with biofilm age. One and 2-d-old untreated biofilms showed higher metamorphosis when compared to 5-d-old biofilms. However, when the biofilms that promoted cyprid metamorphosis were treated with Irgarol 1051 at low concentrations, metamorphosis rates decreased. Cyprids were prevented from metamorphosing completely by biofilms treated at the highest concentration of Irgarol 1051. Inhibition of metamorphosis was also observed in the case of competent polychaete larvae when exposed to Irgarol 1051 compared to those exposed to metamorphosis inducers such as 3-iso-butyl-1-methylxanthine (IBMX) and natural biofilms. Identification of the pathway(s) that caused the promotory biofilms to become toxic when exposed to Irgarol 1051 is discussed.

1-Methyl-3-isobutylxanthine↗
PubMed2005

Early post-larval development of the endoparasitic platyhelminth Mesocestoides corti: trypsin provokes reversible tegumental damage leading to serum-induced cell proliferation and growth.

Mesocestoides corti is a suitable in vitro model for studying the development of human endoparasitic platyhelminthes. Treatment with trypsin, supplemented with fetal bovine serum (FBS), induces M. corti development from larvae (tetrathyridia) to segmented adult worm; however, the role of this protease and of FBS in post-larval development induction remains unknown. To characterize the participation of trypsin enzymatic activity and of FBS in the induction of tetrathyridia growth and development, both stimuli were added to the larvae either together or sequentially. Additionally, specific inhibition of trypsin activity was also monitored. Finally, the effect of the enzyme on the parasite tegument as well as the proliferative activity and location of proliferating cells after induction of tetrathyridia development were also studied. We conclude that trypsin-induced tetrathyridia development to adult worm is FBS-dependent and that the effect of serum factors is dependent upon a previous trypsin-induced reversible damage to the larva tegument. In dividing and non-dividing tetrathyridia, proliferative activity of cells is mainly located within the apical massif in the anterior region and nerve cords of larvae, respectively. In tetrathyridia stimulated to develop to adult worms, an intense proliferative activity is evident along the nerve cords. Our results suggest that in natural infections the tetrathyridia tegument is temporally made permeable to growth factors by proteolytic enzyme activity in the intestine juice of the definitive host, thus leading to development to adult worms.

Animals↗
PubMed2004

Hormonal influence on amylase gene expression during Seabass (Lates calcarifer) larval development.

alpha-Amylase gene expression was detected in newly hatched seabass (Lates calcarifer) larvae and peaked at around first feeding. This suggests a greater importance of carbohydrates during early larval development than might be expected for carnivorous fishes. In vivo cortisol and triiodothyronine (T(3)) treatment of seabass larvae upregulated alpha-amylase gene expression. The identification of a functional glucocorticoid-response element (GRE) on the amylase gene promoter indicates that cortisol (glucocorticoid) stimulation of amylase gene expression is direct via GRE. However no TRE (thyroid-response element) was found on the amylase gene and its promoter, and various concentrations of T(3) (1nM-10microM) also did not induce alpha-amylase gene promoter activity in rat AR42-J cells transfected with the promoter construct, unlike dexamethasone treatment. This suggests that T(3) stimulation of amylase gene expression in vivo was indirect, probably secondary to its promotion of one or more developmental processes.

Amylases↗
PubMed2006

Hox gene expression in larval development of the polychaetes Nereis virens and Platynereis dumerilii (Annelida, Lophotrochozoa).

The bilaterian animals are divided into three great branches: the Deuterostomia, Ecdysozoa, and Lophotrochozoa. The evolution of developmental mechanisms is less studied in the Lophotrochozoa than in the other two clades. We have studied the expression of Hox genes during larval development of two lophotrochozoans, the polychaete annelids Nereis virens and Platynereis dumerilii. As reported previously, the Hox cluster of N. virens consists of at least 11 genes (de Rosa R, Grenier JK, Andreeva T, Cook CE, Adoutte A, Akam M, Carroll SB, Balavoine G, Nature, 399:772-776, 1999; Andreeva TF, Cook C, Korchagina NM, Akam M, Dondua AK, Ontogenez 32:225-233, 2001); we have also cloned nine Hox genes of P. dumerilii. Hox genes are mainly expressed in the descendants of the 2d blastomere, which form the integument of segments, ventral neural ganglia, pre-pygidial growth zone, and the pygidial lobe. Patterns of expression are similar for orthologous genes of both nereids. In Nereis, Hox2, and Hox3 are activated before the blastopore closure, while Hox1 and Hox4 are activated just after this. Hox5 and Post2 are first active during the metatrochophore stage, and Hox7, Lox4, and Lox2 at the late nectochaete stage only. During larval stages, Hox genes are expressed in staggered domains in the developing segments and pygidial lobe. The pattern of expression of Hox cluster genes suggests their involvement in the vectorial regionalization of the larval body along the antero-posterior axis. Hox gene expression in nereids conforms to the canonical patterns postulated for the two other evolutionary branches of the Bilateria, the Ecdysozoa and the Deuterostomia, thus supporting the evolutionary conservatism of the function of Hox genes in development.

Animals↗
PubMed1998

The relationship between faecal egg count reduction and the lethal dose 50% in the egg hatch assay and larval development assay.

The relationship between resistance detected in the faecal egg count reduction test (FECRT) and the lethal dose 50% (LD50) in the egg hatch assay (EHA) for benzimidazoles (BZs) and a larval development assay (LDA) for BZs, levamisole (LEV) and ivermectin (IVM) was examined on 13 sheep farms and 12 goat farms in Denmark. Out of 10 farms where resistance to BZs was detected according to the FECRT, nine (90%) had LD50 values above 0.5 microM thiabendazole (TBZ) (0.1 microg TBZ/ml) in the EHA, indicating resistance to BZs. However, four out of the 12 isolates susceptible to BZs in the FECRT had LD50 values higher than 0.5 microM TBZ in the EHA. For all isolates examined, LD50 values for TBZ in the LDA were lower than in the EHA. Four out of 11 and five out of 12 farms with worm populations resistant to BZs according to the FECRT and EHA respectively, had LD50 values lower than 0.5 microM TBZ in the LDA. Using the same cut-off point for resistant isolates in the LDA as in the EHA (0.5 microM TBZ), these isolates would be considered susceptible to BZs. All 10 isolates susceptible to BZs according to the FECRT and EHA and two isolates with suspect BZ resistance had LD50 values lower than 0.5 microM TBZ in the LDA. The above results indicated fairly good agreement in the detection of BZ resistance between the FECRT, EHA and the LDA. Groups of farms where resistance to LEV was detected according to the FECRT had higher mean LD50 values compared to those with LEV-susceptible or suspected resistant isolates. However, only four out of 12 farms having isolates resistant to LEV had LD50 values higher than 1.2 microM LEV (0.28 microg LEV/ml) recorded previously for a LEV-susceptible strain of Ostertagia circumcincta. This indicated discrepancies in declaring resistance to LEV between the FECRT and the LDA. Isolates from four farms where resistance to IVM was detected in the FECRT had LD50 values higher than the susceptible isolates. These were 2.5 to 7.5 times higher than those recorded previously for IVM-susceptible strains.

Animals↗
PubMed2003

Purification and characterization of an N-acetylglucosamine-binding lectin from Koelreuteria paniculata seeds and its effect on the larval development of Callosobruchus maculatus (Coleoptera: Bruchidae) and Anagasta kuehniella (Lepidoptera: Pyralidae).

This study describes the purification of an N-acetylglucosamine-binding lectin from Koelreuteria paniculata seeds and its effects on the larval development of Callobruchus maculatus and Anagasta kuehniella. The lectin (KpLec) was characterized and isolated by gel filtration, affinity column, and reverse phase chromatography. SDS-PAGE indicated that this lectin is a dimer composed of subunits of 22 and 44 kDa. The N terminus exhibited 40% similarity with Urtiga dioica agglutinin. KpLec was tested for anti-insect activity against C. maculatus and A. kuehniella. With regard to C. maculatus, an artificial diet containing 0.7 and 1% KpLec produced LD(50) and ED(50) value, respectively. However, for A. kuenhiella, an artificial diet containing 0.65% KpLec produced an LD(50), whereas 0.2% KpLec produced an ED(50). The transformation of genes coding for this lectin could be useful in the development of insect resistance in important agricultural crops.

Acetylglucosamine↗
PubMed2006

Metabolic scaling associated with unusual size changes during larval development of the frog, Pseudis paradoxus.

The early larvae of P. paradoxus grow large but metamorphose into relatively small frogs, the diminished post-metamorphic growth producing a marked contrast between maximum larval size and adult. Thus, O(2) uptake does not appear to limit the energy expenditure on growth processes, and unlike in other anuran larvae, may not be a surface area-related function in P. paradoxus larvae. The resting rates of metabolism (M(O(2))) and partitioning between aquatic (Mw(O(2))) and aerial O(2) uptake (Ma(O(2))) were measured on tadpoles and froglets by closed system respirometry, using water of P(O(2)) ranging from 145 to 40 mmHg. Correlative changes in body glycogen and lactate were examined by standard enzyme assays. Scaling patterns in the growth and degrowth stages were analysed on whole-body, log-transformed data using linear regressions. In normoxia, M(O(2)) was 2.1-2.5 mumol g(-1) h(-1) in the early larvae, increasing more than twofold on forelimb emergence and decreasing sharply in the froglets; M(O(2)) varies in strict proportion to body mass (M(b)), both in the growth (b=1.02) and degrowth (b=0.97) phases, according to the equation M(O(2))=aM(b)(b), where b is the scaling coefficient. Mw(O(2)) constitutes >90% of total uptake in the growth stages, increasing with b=1.02 while Ma(O(2)) increases with b=1.13; during degrowth there is a change in the pattern related to intensification of metamorphosis. Hypoxic water did not affect M(O(2)); however, in all larval stages Mw(O(2)) and Ma(O(2)) changed with a decrease in P(O(2)). At 60 mmHg, rates are more severely affected in the largest tadpoles, causing the b values for Mw(O(2)) and Ma(O(2)) to change to 0.11 and 1.44, respectively, in the growth phase. Glycogen and lactate levels increase out of proportion with body mass increase (b=2.05 and 1.47, respectively) in the growth stages, and increase anaerobic capacity in late metamorphosis. In hypoxic water, glycogen levels decrease in the growth stages and the largest tadpoles accumulate surplus lactate, possibly related to surfacing activity. Our results may reveal the consequences of size on energy demand at the tissue level in P. paradoxus larvae, indicating that air breathing must subsidise energy expenditure during larval development.

Animals↗
PubMed1991

Differential regulation of insect globin and actin mRNAs during larval development in Chironomus thummi.

S1 nuclease protection assays were used to measure changes in the steady-state levels of six different globin (Gb) mRNAs in the midge, Chironomus thummi thummi (C. thummi, Diptera) during larval development. Two distinct patterns of change were observed. GbI, IV, VIIB-4 and VIIB-5 transcripts were present in 3rd instar larvae, rose from low levels immediately post-moult to peak levels by day 2-3 of the 4th instar, and then declined, reaching near-basal levels by day 7-8. In contrast, transcripts of GbIII (known from previous studies to be 4th instar-specific) and VI, which were undetectable in the 3rd instar, rose to high levels by day 2 of the 4th instar, but remained elevated thereafter. Our data further showed that closely linked Gb genes were not necessarily expressed in a coordinate manner. Unlike the Gb mRNAs, actin (Act) mRNA levels (measured by slot-blot hybridization to a heterologous probe) increased progressively as a proportion of total RNA during 4th instar development. Therefore, the regulation of C. thummi Gb transcript levels is specific, differing from that of Act and among the Gb mRNAs themselves. Elevated 20-hydroxyecdysone (HE) titer at the 3rd-4th instar moult correlates with the low steady-state levels of Gb mRNAs immediately post-moult. However, other aspects of Gb mRNA profiles cannot be explained on the basis of a direct repressive effect by HE on Gb gene transcription.

Actins↗