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PubMed1990

Salinity tolerance of stable fly (Diptera: Muscidae).

Effects of salinity on the survival, growth, and development of stable fly, Stomoxys calcitrans (L.), were investigated in the laboratory. Larvae failed to develop to pupation when reared in media containing a salinity of 40 parts per thousand (ppt) sodium chloride (NaCl). Maximum salinity supporting larval development equaled the salinity of seawater (34 ppt); the larval LC90 was 24.2 ppt. Deleterious effects of high salinity decreased as larvae matured. Six-day-old larvae reared at a salinity of 34 ppt weighed 79% less than controls, compared with a 36% difference in 9-d-old larvae; by pupation, the difference was only 24%. Salinity did not influence the duration of larval, pupal, or adult stages. Survival of pupae was unimpaired despite a slight increase in number of pupal deformities, and normal adults emerged. Eggs were highly tolerant to saline. They hatched at salinity concentrations lethal to larvae; greater than 50% hatch occurred even when eggs were maintained at 80 ppt NaCl. Sensitivity of larvae to salinities close to that of seawater might be important for control of stable flies inhabiting marine areas.

Animals↗
PubMed1983

The influence of larval maturation on responses of Mamestra brassicae L. (Lepidoptera: Noctuidae) to nuclear polyhedrosis virus infection.

Responses of mature Mamestrae brassica larvae, in the fifth and sixth instars, to nuclear polyhedrosis virus (NPV) have been quantified. There was an 86 fold decrease in susceptibility to virus, related linearly to increasing body weight, for the larval weight range tested. Although the rate of decreasing response to weight was constant, three phases of susceptibility were identified by shifts in the positions of the regression line of log LD50 on log body weight. Larvae above 700 mg were proportionately less susceptible than those between 250 and 700 mg which were, in turn, proportionately less susceptible than those below 250 mg. LT50 responses were inversely related to virus dosage but increased with larval age. This was accompanied by an increase in the proportion of infected larvae that eventually died in the pupal stage. The ratio of LT50 to time remaining for larval development provided a good predictor of the time course of NPV infection for all larval stages. Extensive comparison with a previous study on responses of immature M. brassicae larvae to NPV infection (6) have been included.

Insect Viruses↗
PubMed2001

Genetic analysis of dPsa, the Drosophila orthologue of puromycin-sensitive aminopeptidase, suggests redundancy of aminopeptidases.

Abstract. The Drosophila genome contains a single orthologue of mammalian puromycin-sensitive aminopeptidases, dPsa. Even though dPsa was expressed in many tissues during development, animals lacking dPsa activity were viable. Ubiquitous overexpression of dPsa during embryonic or larval development resulted in lethality and overexpression in isolated tissues during development resulted in localized lesions. These results suggest that even though dPsa function was not essential for viability, dPsa expression must be tightly regulated for normal development. By screening the Drosophila genome we found 43 predicted aminopeptidases and generated a phylogenetic tree of aminopeptidases related to dPsa by sequence. We discuss possible functions of dPsa and the idea that other Drosophila aminopeptidases might perform redundant functions with dPsa for regulating protein turnover.

Amino Acid Sequence↗
PubMed1993

Origin and migration of trochlear, oculomotor and abducent motor neurons in Petromyzon marinus L.

The development of the ocular motor system was studied in 3- to 6-year old larval lampreys with two different retrograde tracers. Motor neurons of the oculomotor and trochlear nuclei are situated closely to one another in younger larvae. Cases in which only trochlear neurons were labelled revealed trochlear motor neurons scattered from the midbrain tegmentum through the anterior medullary velum. We believe this distribution reflects the place of final mitosis (midbrain tegmentum) and subsequent migration (anterior medullary velum) of lamprey trochlear motor neurons. Evidence is also presented for contralateral migration of oculomotor motor neurons and for ventrolateral migration of abducent motor neurons. The distances covered by migrating ocular motor neurons range from 100 to 150 microns in small larvae; these are distances that could be covered easily during the several years duration of larval development in lampreys.

Abducens Nerve↗
PubMed1997

The effect of dominant vestigial alleles upon vestigial-mediated wing patterning during development of Drosophila melanogaster.

The vestigial gene product is required for the completion of wing development in Drosophila melanogaster. In the absence of vestigial gene expression, cells within the larval wing and haltere imaginal discs fail to proliferate normally thus producing adults with severely reduced wings. Of a large number of vestigial mutations that have been characterized, only two are currently known to exist, vestigial(U) and vestigial(W), which manifest a significant dominant phenotype. Both are associated with chromosomal inversions that fuse the majority of the vestigial coding regions to other genes; mastermind in vestigial(U) and invected in vestigial(W) Examination of vestigial expression in the presence of these dominant alleles shows alterations in the disc-specific expression of vestigial during later stages of larval development. These patterning disruptions are specific to cells of the wing imaginal disc, as significant suppression of total levels of vestigial expression within entire larvae could not be detected. This dominant interference of vestigial patterning appears to be mediated in part by the vestigial coding sequences that are within the gene fusions. Further evidence that the dominant phenotype is the result of disrupted vestigial patterning comes from observations that the dominant alleles can be partially suppressed by mutations within the Drosophila-epidermal growth factor receptor gene. Mutagenesis of vestigial(U) and vestigial(W) produced a series of alleles with partially dominant phenotypes that restored various amounts of the adult wing. These phenotypes can be correlated with alterations in specific portions of the vestigial sequences associated with the dominant alleles. In the presence of these partially dominant alleles, wing imaginal discs have significantly more cells which express vestigial compared with the number associated with the original dominant phenotype. Additionally, eliminating some of the dominant effect causes alterations in the patterns of early stage apoptotic cell death associated with dominant vestigial alleles. Utilizing these new vestigial alleles, it is possible to correlate the consequence of altered vestigial expression to subsequent changes in patterning of the wing disc.

Animals↗
PubMed1999

Anaphase aberrations in the embryos of the marine tubeworm Pomatoceros lamarckii (Polychaeta: Serpulidae): a new in vivo test assay for detecting aneugens and clastogens in the marine environment.

The marine environment receives a wide variety of chemical inputs, many of which have the potential to damage DNA or interfere with the process of cell division. Here we describe a new assay based on the early embryo and larval stages of a planktonic spawning, tube dwelling marine worm, Pomatoceros lamarckii, which for experimental purposes has the advantage of producing large numbers of ripe gametes throughout the majority of the year. One of the most promising end-points is the use of dividing cells to detect anaphase aberrations such as lagging chromosomes, tripolar anaphases, acentric fragments and chromosome bridges. Apart from the reference mutagens mitomycin C and cyclophosphamide and the well-documented spindle poison colchicine, we tested the fungicide carbendazim, a primary metabolite of the fungicide benomyl, and thiabendazole, a pesticide and antihelminthic drug; both of which are known to act as aneugens in other test systems. In addition we tested sodium hypochlorite, a widely used oxidizing agent and disinfectant, di-butylphthalate, a commercial plasticizer and suspected aneugen, and sodium chloride, a recognized non-genotoxin. Significant increases in the frequency of anaphase abnormalities occurred with most test compounds at relatively low concentrations, confirming the sensitivity of the new assay. Sodium chloride yielded a negative response except at the highest non-relevant concentrations, where some chromatid stickiness was observed. In addition, the developmental consequences of exposure to these compounds were assessed in 4-8 cell embryos and at 48 h once the embryos had metamorphosed into free swimming larvae. Mitotic inhibition and anaphase aberrations were found to be a more sensitive indicator of genotoxic exposure than larval development, although there was a suggestion of a possible mechanistic link between aneugenicity/clastogenicity and larval fitness. The new test assay provides a rapid and inexpensive method for screening chemicals and effluents destined for release into the marine environment for potential gamete effects.

Animals↗
PubMed1996

The Caenorhabditis elegans gene sem-4 controls neuronal and mesodermal cell development and encodes a zinc finger protein.

Neuronal and mesodermal cell types are generated in separate cell lineages during the larval development of Caenorhabditis elegans. Here we demonstrate that the gene sem-4 is required in both types of lineages for the normal development of neuronal and mesodermal cell types. The sem-4 gene encodes a protein containing seven zinc finger motifs of the C2H2 class, four of which are arranged in two pairs widely separated in the primary sequence of the protein. These pairs of zinc fingers are similar to pairs of zinc fingers in the protein encoded by the Drosophila homeotic gene spalt and in the human transcription factor PRDII-BF1. Analysis of sem-4 alleles suggests that different zinc fingers in the SEM-4 protein may function differentially in neuronal and mesodermal cell types. We propose that sem-4 interacts with different transcription factors in different cell types to control the transcription of genes that function in the processes of neuronal and mesodermal cell development.

Alleles↗
PubMed1993

Prophylactic activity of tetracycline against Brugia pahangi infection in jirds (Meriones unguiculatus).

The ability of oral tetracycline to inhibit the development of third-stage infective larvae (L3) of Brugia pahangi to adult worms in jirds was studied using 2 experimental protocols. Jirds treated with 1.4% tetracycline in drinking water for a period beginning 30 days before inoculation of L3 until 30 days post-inoculation (DPI) had 97% reduction in adult worm recovery compared to untreated controls. Jirds that received 1.2% tetracycline in drinking water beginning 1 day before until either 12 or 26 DPI had adult worm recoveries of 11% and < 1%, respectively. Untreated jirds and those given tetracycline beginning at or later than 13 DPI had similar adult worm recovery (27-29%). Prepatent periods were prolonged, and circulating microfilariae were reduced in jirds given tetracycline from 27 to 54 DPI compared to controls. These data indicate that tetracycline administered to jirds in drinking water inhibits B. pahangi development from L3 to adult worms and suggest that this effect occurs during early larval development. Tetracycline administered to infected jirds prior to and continuing through the onset of patency can also affect development of microfilaremia.

Administration, Oral↗
PubMed1997

Effects of 3,4-methylenedioxymethamphetamine in decomposing tissues on the development of Parasarcophaga ruficornis (Diptera:Sarcophagidae) and detection of the drug in postmortem blood, liver tissue, larvae, and puparia.

Larvae of Parasarcophaga ruficornis (Fabricius) (Diptera: Sarcophagidae) were reared on tissues from rabbits administered different dosages of 3,4-methylenedioxymethamphetamine to study the effects of this drug on the development of this insect species. The rabbits were given 11, 22.5, and 67 mg of the drug via ear vein infusion. These dosages correspond to a 0.5, 1.0, and 2.0 median lethal dose. Larvae from colonies fed on tissues from the rabbit receiving 67 mg and the control developed more rapidly from hours 24 through 114. The period required for completion of larval development was significantly shorter for the larvae from the colony fed on liver tissues from the rabbit receiving the 67 mg dosage. This colony also had the lowest total mortality rate during development. No significant differences were observed among the colonies in the duration of the puparial period. Analyses by liquid chromatography/mass spectrometry of the larvae and empty puparial cases following base extraction detected the drug in quantities directly related to the dosage of the drug administered to the rabbits serving as a food source. These results have implications for the determination of time since death when gauged by the development of this insect species.

Animals↗
PubMedDate not supplied

[The relationship between the population count of black fly larvae and pupae (Simuliidae) in bodies of water and the number of attacking females].

Species of black flies, which develop in abundance in water bodies of Lower Priamurje and are potentially capable of bloodsucking, have not been registered near the blood donors. Only a few number of species developing in water attack for bloodsucking that apparently depends on unfavourable conditions of the larval development. A part of emerging females do not possess sufficient nourishing resources for completion of their gonotrophic cycle and need an additional bloodsucking. Of 35 registered species (27 of them possess morphological devices for bloodsucking) only 11 species attack. 4 species (Byssodon maculata ussuriana, Gnus malyshevi albipes, G. pavlovskii, Prosimulium ex gr. hirtipes) are mass bloodsuckers.

Animals↗
PubMed2002

Heterogeneity of chondroitin sulfate glycosaminoglycan localization during early development of the striped bass (Morone saxatilis).

Recent studies have suggested important functions for proteoglycan-associated chondroitin sulfate glycosaminoglycans (GAGs) during embryonic and larval development in numerous organisms, including the teleost. Little is known, however, about the specific distribution of different chondroitin sulfate GAGs during early development. The present study utilized immunohistochemistry to localize chondroitin sulfate GAG antigens during development of the striped bass (Morone saxatilis). Immunoreagents utilized were monoclonal antibodies (MAbs) TC2, d1C4, and CS-56, which recognize, respectively, native epitopes on glycosaminoglycan chains enriched in chondroitin-4-, chondroitin-6-, and both chondroitin-4- and -6-sulfate. Little or no immunoreactivity was observed in gastrulating embryos at 18 hr postfertilization with any MAb tested. By 24 hr (8 somites), the CS-56 epitope was localized around the notochord. At hatching (48 hr) and early larval (72 hr) stages, d1C4 and CS-56 antigens codistributed in some sites (e.g., the notochord and myosepta), but a striking heterogeneity of chondroitin sulfate GAG localization was observed in other developing tissues, including the eye and specific subsets of basement membrane. At these latter time points, TC2 reacted primarily with the extracellular matrix of the developing heart, particularly the ventricular and conotruncal segments. Heterogeneous patterning of these chondroitin sulfate GAG epitopes suggests dynamic regulation of proteoglycan function during critical morphogenetic events in early development of the striped bass.

Animals↗
PubMed1993

Dynamic life table model for Aedes aegypti (diptera: Culicidae): simulation results and validation.

The container-inhabiting mosquito simulation model (CIMSiM) is a weather-driven, dynamic life table simulation model of Aedes aegypti (L.) and similar nondiapausing Aedes mosquitoes that inhabit artificial and natural containers. This paper presents a validation of CIMSiM simulating Ae. aegypti using several independent series of data that were not used in model development. Validation data sets include laboratory work designed to elucidate the role of diet on fecundity and rates of larval development and survival. Comparisons are made with four field studies conducted in Bangkok, Thailand, on seasonal changes in population dynamics and with a field study in New Orleans, LA, on larval habitat. Finally, predicted ovipositional activity of Ae. aegypti in seven cities in the southeastern United States for the period 1981-1985 is compared with a data set developed by the U.S. Public Health Service. On the basis of these comparisons, we believe that, for stated design goals, CIMSiM adequately simulates the population dynamics of Ae. aegypti in response to specific information on weather and immature habitat. We anticipate that it will be useful in simulation studies concerning the development and optimization of control strategies and that, with further field validation, can provide entomological inputs for a dengue virus transmission model.

Aedes↗
PubMed2003

Biological targets of neurotoxic pesticides analysed by alteration of developmental events in the Mediterranean sea urchin, Paracentrotus lividus.

Biological effects of neurotoxic insecticides widely used for agricultural purposes were studied using the early development of the Mediterranean sea urchin Paracentrotus lividus as a model. These compounds, dispersed as aerosols or powders in agricultural regions near to the coast, may affect the health of organisms in the marine environment. The biological effects of Basudin (an organophosphate compound containing 20% Diazinon), Diazinon (Dzn, a thionophosphate), Carbaryl and Pirimicarb (carbamates) on the early phases of sea urchin development were thus investigated. Morphological, biochemical, histochemical and immuno histochemical analyses were performed both during embryo and larval development. For the morphological effects on fertilisation and first cleavages, the effective concentration of insecticides was found to be 10(-4) M, while for further stages concentrations between 10(-5) and 10(-7) M were effective: 10(-3) M of any of these insecticides totally arrested development. During embryonic development, the treatment with organophosphates slowed the rate of early mitotic cycles down, affected nuclear and cytoskeletal status as well as DNA synthesis. From the gastrulation stage onwards, the main effects were exerted on the rate of primary mesenchyme cells migration, larval size, perioral arm length, and acetylcholinesterase activity distribution, thus deregulating the cholinergic system, which modulates cell-to-cell communication mediated by the signal molecule acetylcholine.

Acetylcholinesterase↗
PubMed1993

Expression of the Drosophila optomotor-blind gene transcript in neuronal and glial cells of the developing nervous system.

Mutations in the complex gene locus optomotor-blind (omb) can lead to defects in the development of both the optic lobes and external features of the adult fly. We describe here the expression of omb in the developing and adult nervous system using in situ hybridization. During embryogenesis, omb expression is first observed in the optic lobe anlagen. It later expands to a larger part of the developing larval brain and to the gnathal lobes. Cells in the ventral and peripheral nervous systems begin to express omb after completion of germ band extension. Later in embryonic development, expression declines and only persists in the antennomaxillary complex and in part of the brain hemispheres. During the larval and pupal stages, omb expression in the brain is confined to the developing optic lobes and contiguous regions of the central brain. At these stages, only a few cells show expression in the ventral ganglion. In the eye imaginal disc, transcript accumulation is most conspicuous in a group of presumptive glia precursor cells posterior to the morphogenetic furrow and in the optic stalk. In the adult brain, expression is prominent in several regions of the optic lobe cortex and along the border between central brain and optic lobes. In the mutation In(1)ombH31, 40 kb of regulatory DNA, downstream from the transcription unit, are removed from the omb gene. In(1)ombH31 is characterized by the lack of a set of giant interneurons from the lobula plate of the adult optic lobes. We find that, already during embryogenesis, there is a drastic difference between wild type and In(1)ombH31 in the level of the omb transcript in the optic lobe primordia. The adult mutant phenotype may thus be caused by omb misexpression during embryonic development.

Animals↗
PubMed1994

Notch1 is essential for postimplantation development in mice.

The Notch gene of Drosophila encodes a large transmembrane protein involved in cell fate determination during embryonic and larval development. This gene is evolutionarily conserved, and Notch homologs have been cloned from several vertebrate species. To examine the in vivo role of the Notch1 gene, a mouse homolog of Notch, a mutation was introduced by targeted disruption in embryonic stem cells, and these cells were used to generate mutant mice. Intercrosses of animals heterozygous for the Notch1 mutation yielded no live-born homozygous mutant offspring. Homozygous mutant embryos died before 11.5 days of gestation. Morphological and histological analysis of the homozygous mutant embryos indicated that pattern formation through the first nine days of gestation appeared largely normal. However, histological analysis of mutant embryos subsequent to this stage revealed widespread cell death. Death of mutant embryos did not appear to be attributable to defects in placentation or vascularization. Examination of the RNA expression pattern of the Notch2 gene, another Notch gene family member, indicated that it partially overlapped the Notch1 expression pattern. Genetic analysis of the Notch1 mutation also demonstrated that it was not allelic to a mouse mutation described previously, Danforth's short tail (Sd). These results demonstrate that the Notch1 gene plays a vital role during early postimplantation development in mice.

Animals↗
PubMed1997

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

Journal Article↗
PubMed1985

Alternative processing and developmental control of the transcripts of the Drosophila abl oncogene homologue.

Drosophila sequences homologous to the abl oncogene are located near the 5' end of a gene (Dash). The Dash gene is transcribed to give long RNAs (5-6 kb) and short RNAs (3.0 kb) that lack some of the internal exons of the gene including some of the sequences coding for the protein kinase domain. The gene is composed of at least five short exons and a long 3' exon. The 3' exon is processed in several alternative ways. It contains an intronic sequence which is spliced out in approximately 50% of the transcripts. S1 mapping shows the existence of five different 3' ends, presumed polyadenylation sites, differing by up to 1 kb. Three of these are maternal-specific while the other two are utilised during development. Dash RNA is most abundant in eggs and early embryos, becomes very rare during larval development and returns in a burst of activity in early pupae.

Animals↗
PubMed1996

Developmental switching in the parasitic nematode Strongyloides ratti.

Strongyloides ratti is a nematode parasite of rats. It is able to undergo two types of development outside the host: heterogonic (free-living adults and sexual reproduction) and homogonic (direct larval development). Homogonic development has a number of similarities with the development of the dauer stage of free-living nematodes, including Caenorhabditis elegans. Using isofemale lines of the parasite, factors that control this developmental choice have been investigated. Isofemale lines can be selected for both heterogonic and homogonic development, but are still able to respond to environmental conditions. By using temperature shift experiments it has been possible to determine when larvae become developmentally committed. All larvae are developmentally committed after 24 h at 19 degrees C.

Animals↗