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Sample records for larval development evaluacion

  1. The development of the Drosophila larval brain.

    PubMed

    Hartenstein, Volker; Spindler, Shana; Pereanu, Wayne; Fung, Siaumin

    2008-01-01

    In this chapter we will start out by describing in more detail the progenitors of the nervous system, the neuroblasts and ganglion mother cells. Subsequently we will survey the generic cell types that make up the developing Drosophila brain, namely neurons, glial cells and tracheal cells. Finally, we will attempt a synopsis of the neuronal connectivity of the larval brain that can be deduced from the analysis of neural lineages and their relationship to neuropile compartments. PMID:18683635

  2. Larval development of Evermannia zosterura (Perciformes: Gobiidae).

    PubMed

    González-Navarro, Enrique; Saldierna-Martínez, Ricardo Javier; Aceves-Medina, Gerardo

    2014-06-01

    Gobiidae is the most specious fish family in the world with almost 2 000 species, however only 11% of them have been described for their larval stages. The entire life cycle information is essential to understand the biology and ecology of this important fish group. Previous studies on zooplankton samples from Ensenada de La Paz, México, have shown the presence of several Gobiidae larvae and juveniles which were identified as Evermania zosterura. The main objective of this work was to describe the larval stages of this species, widely distributed in the Eastern tropical Pacific. The development of E. zosterura larvae was described based on 66 specimens. A total of 53 specimens were used to describe morphometrics and pigmentation patterns, while 13 specimens were cleared and stained, to obtain meristic characteristics. Cleared specimens had 30 to 31 total vertebrae; dorsal-fin elements: IV; 1, 13-14, anal-fin elements: 1, 13-14, and most had pterygiophore formula 4-111100. The combination of these characteristics confirmed these specimens as E. zosterura. The pigment pattern is similar throughout ontogeny. Larvae are characterized by having three to five dendritic melanophores along the post-anal ventral margin, four to nine smaller melanophores along the ventral margin between the isthmus and anus, and one on the midpoint of the dorsal margin of the tail. There is one small pigment spot on the angle of the jaw, and other on the tip of lower lip. There is an elongated internal pigment under the notochord, between the head and gas bladder. Notochord flexion starts near 3.5mm BL and ends at 4.6mm BL; transformalion to the juvenile stage is at about 13.6mm BL. Our conclusion is that the most useful characters to distinguish this species early-larval stages from those of similar species in the area, are the number of myomeres, the large melanophores (approximately uniformly in size) on the post anal ventral margin, and the elongate internal pigment under the notochord

  3. Phormidium animalis (Cyanobacteria: Oscillatoriaceae) supports larval development of Anopheles albimanus.

    PubMed

    Vázquez-Martínez, M Guadalupe; Rodríguez, Mario H; Arredondo-Jiménez, Juan I; Méndez-Sánchez, José D

    2003-06-01

    The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitats of Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated. First-stage larvae were reared under insectary conditions with P. animalis ad libitum and their development was compared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by wing length, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria. Nevertheless, these observations indicate that P. animalis is ingested and assimilated by larval An. albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidal toxins for malaria control in the region. PMID:12825668

  4. LARVAL DEVELOPMENT OF THE SPIDER CRAB, 'LIBINIA EMERGINATA' (MAJIDAE)

    EPA Science Inventory

    Larval development of the spider crab, Libinia emarginata, consists of two zoeal stages and megalopa. Laboratory-reared larvae (South Carolina and Rhode Island) are described and compared with planktonic larvae from Narragansett Bay, RI. No significant variations in morphology we...

  5. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

    NASA Technical Reports Server (NTRS)

    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-01-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

  6. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

    NASA Astrophysics Data System (ADS)

    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-08-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by intrduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spaceflight, and show that extensive degress of development can take place in this microgravity environment.

  7. Social coercion of larval development in an ant species

    NASA Astrophysics Data System (ADS)

    Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

    2016-04-01

    Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults.

  8. Social coercion of larval development in an ant species.

    PubMed

    Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

    2016-04-01

    Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults. PMID:26874941

  9. Development of Drosophila larval neuromuscular junctions: maintaining synaptic strength.

    PubMed

    Li, H; Peng, X; Cooper, R L

    2002-01-01

    In spite of the available information about the development of Drosophila neuromuscular junctions, the correlation between nerve terminal morphology and maintenance of synaptic strength has still not been systematically addressed throughout larval development. We characterized the growth of the abdominal longitudinal muscle 6 (m6) and the motor terminals Ib and Is that innervate it within segment 4. In addition, we measured the evoked excitatory junction potential (EJP) amplitudes while the Ib and Is axons were selectively recruited. Regression analysis with natural log transformation of response variables indicated that the developmental curves for m6 and the motor axons Ib and Is were best fitted as second order polynomial regressions during larval development. Initially Is terminals are longer and possess more synaptic varicosities at the first instar stage. The Is terminals also grow faster in subsequent developmental stages. The growth of nerve terminals and their target m6 are not proportional although tightly correlated. This results in a larger average muscle area innervated by a single varicosity as the animal develops. The amplitudes of the EJPs of Ib and Is neurons show no developmental difference in their amplitudes from the first to the late third larval instar. The Is axon consistently produced larger EJPs than the Ib axon at each developmental stage. The time constants for both rising and decay phases of EJPs increase exponentially throughout larval development. The results presented not only help in quantifying the normal development of Drosophila neuromuscular junctions, but also provide a framework for future investigations to properly interpret developmental abnormalities that may occur in various mutants. PMID:12421617

  10. Food selection in larval fruit flies: dynamics and effects on larval development

    NASA Astrophysics Data System (ADS)

    Schwarz, Sebastian; Durisko, Zachary; Dukas, Reuven

    2014-01-01

    Selecting food items and attaining a nutritionally balanced diet is an important challenge for all animals including humans. We aimed to establish fruit fly larvae ( Drosophila melanogaster) as a simple yet powerful model system for examining the mechanisms of specific hunger and diet selection. In two lab experiments with artificial diets, we found that larvae deprived of either sucrose or protein later selectively fed on a diet providing the missing nutrient. When allowed to freely move between two adjacent food patches, larvae surprisingly preferred to settle on one patch containing yeast and ignored the patch providing sucrose. Moreover, when allowed to move freely between three patches, which provided either yeast only, sucrose only or a balanced mixture of yeast and sucrose, the majority of larvae settled on the yeast-plus-sucrose patch and about one third chose to feed on the yeast only food. While protein (yeast) is essential for development, we also quantified larval success on diets with or without sucrose and show that larvae develop faster on diets containing sucrose. Our data suggest that fruit fly larvae can quickly assess major nutrients in food and seek a diet providing a missing nutrient. The larvae, however, probably prefer to quickly dig into a single food substrate for enhanced protection over achieving an optimal diet.

  11. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development

    PubMed Central

    Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A.; Weinstein, Philip; Foo, Dahlia; Allen, Geoff R.

    2015-01-01

    Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level). To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission. PMID:26558896

  12. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development.

    PubMed

    Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A; Weinstein, Philip; Foo, Dahlia; Allen, Geoff R

    2015-01-01

    Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level). To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission. PMID:26558896

  13. Proteomic analysis through larval development of Solea senegalensis flatfish.

    PubMed

    Chicano-Gálvez, Eduardo; Asensio, Esther; Cañavate, José Pedro; Alhama, José; López-Barea, Juan

    2015-12-01

    The post-embryonic development of the Senegalese sole, Solea senegalensis, a flatfish of growing interest in fisheries and aquaculture, is associated with drastic morpho-physiological changes during metamorphosis. Although in the last two decades knowledge on sole culture has notably increased, especially in Southern Europe, its progress was restricted due to lack of methods to control reproduction, improve larval quality and increase juvenile disease resistance. A limited knowledge of the physiological, molecular and genetic mechanisms involved is at the base of such limitation. A proteomic study was carried out to explore the molecular events that occur during S. senegalensis ontogenesis. Protein expression changes were monitored in larvae from 5 to 21 dph by combining 2DE and protein identification with de novo MS/MS sequencing. An average of 6177 ± 282 spots was resolved in 2DE gels. Hierarchical cluster analysis of the 705 selected spots grouped them in eight patterns. Thirty-four proteins were identified and assigned biological functions including structure, metabolism highlighting energy metabolism, transport, protein folding, stress response, chromatin organization and regulation of gene expression. These changes provide a sequential description of the molecular events associated with the biochemical and biological transformations that occur during sole larval development. PMID:26365915

  14. Development and plasticity of the Drosophila larval neuromuscular junction

    PubMed Central

    Menon, Kaushiki P.; Carrillo, Robert A.; Zinn, Kai

    2013-01-01

    The Drosophila larval neuromuscular system is relatively simple, containing only 32 motor neurons in each abdominal hemisegment, and its neuromuscular junctions (NMJs) are large, individually specified, and easy to visualize and record from. NMJ synapses exhibit developmental and functional plasticity while displaying stereotyped connectivity. Drosophila Type I NMJ synapses are glutamatergic, while the vertebrate NMJ uses acetylcholine as its primary neurotransmitter. The larval NMJ synapses use ionotropic glutamate receptors (GluRs) that are homologous to AMPA-type glutamate receptors in the mammalian brain, and they have postsynaptic scaffolds that resemble those found in mammalian postsynaptic densities. These features make the Drosophila neuromuscular system an excellent genetic model for the study of excitatory synapses in the mammalian central nervous system. The first section of the review presents an overview of NMJ development. The second section describes genes that regulate NMJ development, including: 1) genes that positively and negatively regulate growth of the NMJ; 2) genes required for maintenance of NMJ bouton structure; 3) genes that modulate neuronal activity and alter NMJ growth; 4) genes involved in trans-synaptic signaling at the NMJ. The third section describes genes that regulate acute plasticity, focusing on translational regulatory mechanisms. Since this review is intended for a developmental biology audience, it does not cover NMJ electrophysiology in detail, and does not review genes for which mutations produce only electrophysiological but no structural phenotypes. PMID:24014452

  15. Biased gene expression in early honeybee larval development

    PubMed Central

    2013-01-01

    Background Female larvae of the honeybee (Apis mellifera) develop into either queens or workers depending on nutrition. This nutritional stimulus triggers different developmental trajectories, resulting in adults that differ from each other in physiology, behaviour and life span. Results To understand how these trajectories are established we have generated a comprehensive atlas of gene expression throughout larval development. We found substantial differences in gene expression between worker and queen-destined larvae at 6 hours after hatching. Some of these early changes in gene expression are maintained throughout larval development, indicating that caste-specific developmental trajectories are established much earlier than previously thought. Within our gene expression data we identified processes that potentially underlie caste differentiation. Queen-destined larvae have higher expression of genes involved in transcription, translation and protein folding early in development with a later switch to genes involved in energy generation. Using RNA interference, we were able to demonstrate that one of these genes, hexamerin 70b, has a role in caste differentiation. Both queen and worker developmental trajectories are associated with the expression of genes that have alternative splice variants, although only a single variant of a gene tends to be differentially expressed in a given caste. Conclusions Our data, based on the biases in gene expression early in development together with published data, supports the idea that caste development in the honeybee consists of two phases; an initial biased phase of development, where larvae can still switch to the other caste by differential feeding, followed by commitment to a particular developmental trajectory. PMID:24350621

  16. Embryonic and larval development of Brycon amazonicus (SPIX & AGASSIZ, 1829).

    PubMed

    Nakauth, A C S Sampaio; Villacorta-Correa, M A; Figueiredo, M R; Bernardino, G; França, J M

    2016-02-01

    The objective of this study was to describe the embryonic and larval development of Brycon amazonicus, featuring the main events up to 50 hours after fertilization (AF). The material was provided by the Aquaculture Training, Technology and Production Center, Presidente Figueiredo (AM). The characterization was based on stereomicroscopic examination of the morphology of eggs, embryos and larvae and comparison with the literature. Matrinxã eggs are free, transparent, and spherical, with a perivitelline space of 0.56 ± 0.3 mm. The successive divisions give rise to cells with 64 blastomeres during the first hour AF. The gastrula stage, beginning 02 h 40 min AF, was characterized by progressive regression cells and the formation of the embryonic axis, leading to differentiation of the head and tail 05 h 30 min AF. From 06 to 09 h AF the somites, notochord, otic and optic vesicles and otoliths were observed, in addition to heart rate and the release of the tail. The larvae hatched at 10 h 30 min AF (29.9 °C), with a total length of 3.56 ± 0.46 mm. Between 19 and 30 h AF, we observed 1) pigmentation and gut formation, 2) branchial arches, 3) pectoral fins, 4) a mouth opening and 5) teeth. Cannibalism was initiated earlier (34 h AF) which was associated with rapid yolk absorption (more than 90% until 50 h AF), signaling the need for an exogenous nutritional source. The environmental conditions (especially temperature) influenced the time course of some events throughout the embryonic and larval development, suggesting the need for further studies on this subject. PMID:26909629

  17. Ascorbic Acid Influences the Development and Immunocompetence of Larval Heliothis virescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report that ascorbic acid, which is known to be a free radical scavenger, to be important not only in insect development but also in larval resistance to baculovirus infection. We sequentially elevated the ascorbic acid content in diet and evaluated the effect on larval H. virescens development ...

  18. Correlated Evolution between Mode of Larval Development and Habitat in Muricid Gastropods

    PubMed Central

    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Abstract Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids

  19. Correlated evolution between mode of larval development and habitat in muricid gastropods.

    PubMed

    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods

  20. Effects of Disinfectants on Larval Development of Ascaris suum Eggs.

    PubMed

    Oh, Ki-Seok; Kim, Geon-Tae; Ahn, Kyu-Sung; Shin, Sung-Shik

    2016-02-01

    The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at 25˚C in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely. PMID:26951988

  1. Effects of Disinfectants on Larval Development of Ascaris suum Eggs

    PubMed Central

    Oh, Ki-Seok; Kim, Geon-Tae; Ahn, Kyu-Sung; Shin, Sung-Shik

    2016-01-01

    The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at 25˚C in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely. PMID:26951988

  2. Elevated major ion concentrations inhibit larval mayfly growth and development.

    PubMed

    Johnson, Brent R; Weaver, Paul C; Nietch, Christopher T; Lazorchak, James M; Struewing, Katherine A; Funk, David H

    2015-01-01

    Anthropogenic disturbances, including those from developing energy resources, can alter stream chemistry significantly by elevating total dissolved solids. Field studies have indicated that mayflies (Order Ephemeroptera) are particularly sensitive to high total dissolved solids. In the present study, the authors measured 20-d growth and survivorship of larval Neocloeon triangulifer exposed to a gradient of brine salt (mixed NaCl and CaCl2 ) concentrations. Daily growth rates were reduced significantly in all salt concentrations above the control (363 µS cm(-1) ) and larvae in treatments with specific conductance >812 µS cm(-1) were in comparatively earlier developmental stages (instars) at the end of the experiment. Survivorship declined significantly when specific conductance was >1513 µS cm(-1) and the calculated 20-d 50% lethal concentration was 2866 µS cm(-1) . The present study's results provide strong experimental evidence that elevated ion concentrations similar to those observed in developing energy resources, such as oil and gas drilling or coal mining, can adversely affect sensitive aquatic insect species. PMID:25307284

  3. Larval development of Culex quinquefasciatus in water with low to moderate.

    PubMed

    Noori, Navideh; Lockaby, B Graeme; Kalin, Latif

    2015-12-01

    Population growth and urbanization have increased the potential habitats, and consequently the abundance of Culex quinquefasciatus, the southern house mosquito, a vector of West Nile Virus in urban areas. Water quality is critical in larval habitat distribution and in providing microbial food resources for larvae. A mesocosm experiment was designed to demonstrate which specific components of water chemistry are conducive to larval Culex mosquitoes. Dose-response relationships between larval development and NO3 , NH4 , and PO4 concentrations in stream water were developed through this experiment to describe the isolated effects of each nutrient on pre-adult development. The emergence pattern of Culex mosquitoes was found to be strongly related to certain nutrients, and results showed that breeding sites with higher PO4 or NO3 concentrations had higher larval survival rates. High NO3 concentrations favor the development of male mosquitoes and suppress the development of female mosquitoes, but those adult females that do emerge develop faster in containers with high NO3 levels compared to the reference group. The addition of PO4 in the absence of nitrogen sources to the larval habitat slowed larval development, however, it took fewer days for larvae to reach the pupal stage in containers with combinations of NO3 and PO4 or NH4 and PO4 nutrients. Results from this study may bolster efforts to control WNV in urban landscapes by exploring water quality conditions of Culex larval habitats that produce adult mosquitoes. PMID:26611953

  4. Effect of ace inhibitors and TMOF on growth, development, and trypsin activity of larval Spodoptera littoralis.

    PubMed

    Lemeire, Els; Borovsky, Dov; Van Camp, John; Smagghe, Guy

    2008-12-01

    Angiotensin converting enzyme (ACE) is a zinc metallopeptidase capable of cleaving dipeptide or dipeptideamide moieties at the C-terminal end of peptides. ACE is present in the hemolymph and reproductive tissues of insects. The presence of ACE in the hemolymph and its broad substrate specificity suggests an important role in processing of bioactive peptides. This study reports the effects of ACE inhibitors on larval growth in the cotton leafworm Spodoptera littoralis. Feeding ACE inhibitors ad lib decreased the growth rate, inhibited ACE activity in the larval hemolymph, and down-regulated trypsin activity in the larval gut. These results indicate that S. littoralis ACE may influence trypsin biosynthesis in the larval gut by interacting with a trypsin-modulating oostatic factor (TMOF). Injecting third instar larvae with a combination of Aea-TMOF and the ACE inhibitor captopril, down-regulated trypsin biosynthesis in the larval gut indicating that an Aea-TMOF gut receptor analogue could be present. Injecting captopril and enalapril into newly molted fifth instar larvae stopped larval feeding and decreased weight gain. Together, these results indicate that ACE inhibitors are efficacious in stunting larval growth and ACE plays an important role in larval growth and development. PMID:18949805

  5. Effect of three larval diets on larval development and male sexual performance of Anopheles gambiae s.s.

    PubMed

    Yahouédo, Gildas A; Djogbénou, Luc; Saïzonou, Jacques; Assogba, Bénoît S; Makoutodé, Michel; Gilles, Jeremie R L; Maïga, Hamidou; Mouline, Karine; Soukou, Bhonna K; Simard, Frédéric

    2014-04-01

    Population replacement/elimination strategies based on mass-release of sterile or otherwise genetically modified (male) mosquitoes are being considered in order to expand the malaria vector control arsenal on the way to eradication. A challenge in this context, is to produce male mosquitoes that will be able to compete and mate with wild females more efficiently than their wild counterparts, i.e. high fitness males. This study explored the effect of three larval food diets developed by the International Atomic Energy Agency on the overall fitness and mating performance of male Anopheles gambiae s.s. mosquitoes (Kisumu strain). Larval development (pupation and emergence rate, development time) was monitored, and adult wing length and energy reserves at emergence (i.e. lipids, sugars, glycogen and proteins) were measured. Male sexual performance was assessed through an insemination test whereby one male and 10 virgin females were maintained together in the same cage in order to record the number of inseminated females per 24h. Our results show that males reared on Diets 2 and 3 performed best during larval development. Males provided with treatment 2.2 had a shorter development time and performed best in insemination tests. However, these males had the lowest overall lifespan, suggesting a trade-off between longevity and sexual performances which needs to be taken into consideration when planning release. The results from this work were discussed in the context of sterile insect techniques or genetic control methods which is today one of the strategy in the overall mosquito control and elimination efforts. PMID:24291460

  6. La Evaluacion del Desarrollo de los Alumnos Preescolares (Assessing the Development of Preschoolers). ERIC Digest.

    ERIC Educational Resources Information Center

    Katz, Lilian G.

    To help parents address those aspects of their child's development which may need special encouragement, support, or intervention, this digest delineates 11 categories of behavior for assessment. Parents should not be alarmed if their children are having difficulty in only a few categories, and they should not judge their children's permanent…

  7. INFLUENCE OF AN INSECT GROWTH REGULATOR ON THE LARVAL DEVELOPMENT OF AN ESTUARINE SHRIMP

    EPA Science Inventory

    The influence of methoprene, an insect growth regulator used in mosquito control, on larval development of the estuarine grass shrimp (Palaemonetes pugio) was examined in the laboratory. o grass shrimp larvae successfully completed metamorphosis when continuously exposed to 1000 ...

  8. Larval development of the subantarctic king crabs Lithodes santolla and Paralomis granulosa reared in the laboratory

    NASA Astrophysics Data System (ADS)

    Calcagno, J. A.; Anger, K.; Lovrich, G. A.; Thatje, S.; Kaffenberger, A.

    2004-02-01

    The larval development and survival in the two subantarctic lithodid crabs Lithodes santolla (Jaquinot) and Paralomis granulosa (Molina) from the Argentine Beagle Channel were studied in laboratory cultures. In L. santolla, larval development lasted about 70 days, passing through three zoeal stages and the megalopa stage, with a duration of approximately 4, 7, 11 and 48 days, respectively. The larval development in P. granulosa is more abbreviated, comprising only two zoeal stages and the megalopa stage, with 6, 11 and 43 days' duration, respectively. In both species, we tested for effects of presence versus absence of food (Artemia nauplii) on larval development duration and survival rate. In P. granulosa, we also studied effects of different rearing conditions, such as individual versus mass cultures, as well as aerated versus unaerated cultures. No differences in larval development duration and survival were observed between animals subjected to those different rearing conditions. The lack of response to the presence or absence of potential food confirms, in both species, a complete lecithotrophic mode of larval development. Since lithodid crabs are of high economic importance in the artisanal fishery in the southernmost parts of South America, the knowledge of optimal rearing conditions for lithodid larvae is essential for future attempts at repopulating the collapsing natural stocks off Tierra del Fuego.

  9. Larval and metamorphic development of the foregut and proboscis in the caenogastropod Marsenina (Lamellaria) stearnsii.

    PubMed

    Page, L R

    2002-05-01

    The specialized, postmetamorphic feeding structures of predatory caenogastropods evolved by changes to an ancestral caenogastropod developmental program that generated a planktotrophic larval stage followed by a herbivorous postmetamorphic stage. As part of a program of comparative studies aimed at reconstructing these developmental changes, I studied the development of the postmetamorphic feeding system of Marsenina stearnsii using histological sections for light microscopy and scanning and transmission electron microscopy. The feeding system of this species has two very different designs during ontogeny. The larval system uses ciliary effectors to capture and ingest microalgae, whereas the juvenile/adult system includes a proboscis, jaws, and radular apparatus for predation on ascidian zooids. The postmetamorphic foregut begins to develop during the early larval phase, but the anlagen does not interfere with larval feeding because it develops as an increasingly elaborate outpocketing from the ventral wall of the larval esophagus. At metamorphosis, an opening is created in the anterior tip of the prospective, postmetamorphic buccal cavity and the margins of this opening anneal with the metamorphically remodeled lips of the larval mouth. This process exposes the jaws, which differentiate within the buccal cavity prior to metamorphosis. As a working hypothesis, I suggest that rupture of the buccal cavity to the outside at metamorphosis was selected as a mechanism to allow precocious development of jaws in species where jaws enhanced feeding performance by young juveniles. The larval esophagus of M. stearnsii appears to be completely destroyed at metamorphosis. Larval esophageal cells have distinctive apical characteristics (cilia, blebbed microvilli, stacks of lamellae within the glycocalyx) and no cells having this signature persist through metamorphosis. Development of the proboscis and proboscis sac, which begins prior to metamorphosis, conforms to previous

  10. Exploration of the "larval pool": development and ground-truthing of a larval transport model off leeward Hawai'i.

    PubMed

    Wren, Johanna L K; Kobayashi, Donald R

    2016-01-01

    Most adult reef fish show site fidelity thus dispersal is limited to the mobile larval stage of the fish, and effective management of such species requires an understanding of the patterns of larval dispersal. In this study, we assess larval reef fish distributions in the waters west of the Big Island of Hawai'i using both in situ and model data. Catches from Cobb midwater trawls off west Hawai'i show that reef fish larvae are most numerous in offshore waters deeper than 3,000 m and consist largely of pre-settlement Pomacanthids, Acanthurids and Chaetodontids. Utilizing a Lagrangian larval dispersal model, we were able to replicate the observed shore fish distributions from the trawl data and we identified the 100 m depth strata as the most likely depth of occupancy. Additionally, our model showed that for larval shore fish with a pelagic larval duration longer than 40 days there was no significant change in settlement success in our model. By creating a general additive model (GAM) incorporating lunar phase and angle we were able to explain 67.5% of the variance between modeled and in situ Acanthurid abundances. We took steps towards creating a predictive larval distribution model that will greatly aid in understanding the spatiotemporal nature of the larval pool in west Hawai'i, and the dispersal of larvae throughout the Hawaiian archipelago. PMID:26855873

  11. Muscle organizers in Drosophila: the role of persistent larval fibers in adult flight muscle development

    NASA Technical Reports Server (NTRS)

    Farrell, E. R.; Fernandes, J.; Keshishian, H.

    1996-01-01

    In many organisms muscle formation depends on specialized cells that prefigure the pattern of the musculature and serve as templates for myoblast organization and fusion. These include muscle pioneers in insects and muscle organizing cells in leech. In Drosophila, muscle founder cells have been proposed to play a similar role in organizing larval muscle development during embryogenesis. During metamorphosis in Drosophila, following histolysis of most of the larval musculature, there is a second round of myogenesis that gives rise to the adult muscles. It is not known whether muscle founder cells organize the development of these muscles. However, in the thorax specific larval muscle fibers do not histolyze at the onset of metamorphosis, but instead serve as templates for the formation of a subset of adult muscles, the dorsal longitudinal flight muscles (DLMs). Because these persistent larval muscle fibers appear to be functioning in many respects like muscle founder cells, we investigated whether they were necessary for DLM development by using a microbeam laser to ablate them singly and in combination. We found that, in the absence of the larval muscle fibers, DLMs nonetheless develop. Our results show that the persistent larval muscle fibers are not required to initiate myoblast fusion, to determine DLM identity, to locate the DLMs in the thorax, or to specify the total DLM fiber volume. However, they are required to regulate the number of DLM fibers generated. Thus, while the persistent larval muscle fibers are not obligatory for DLM fiber formation and differentiation, they are necessary to ensure the development of the correct number of fibers.

  12. Effects of ammonia on fertilization, development, and larval survival in the Northern Pacific asteroid, Asterias amurensis.

    PubMed

    Lee, Chang-Hoon; Sung, Chan-Gyoung; Moon, Seong-Dae; Lee, Jong-Hyeon

    2013-07-01

    For developing a complementary test organism to sea urchin during winter in Korea, sensitivities of sperm, embryo, and larvae of Asterias amurensis to un-ionized ammonia were evaluated. The EC₅₀s (Mean ± SD, n = 3) for fertilization and development were 169 ± 62 and 70 ± 19 μg/L, respectively. The 48, 72, and 96-h LC₅₀s for larval survival were 1,674 ± 583, 498 ± 221, and 336 ± 107 μg/L, respectively. The sensitivities of fertilization, development, and larval survival tests with A. amurensis are higher than or comparable to those of sea urchin and other taxonomic groups. Therefore, fertilization, development, and larval survival tests using A. amurensis are suitable for assessing pore water toxicity of marine sediments in Korea. PMID:23674221

  13. Modeling larval connectivity of the Atlantic surfclams within the Middle Atlantic Bight: Model development, larval dispersal and metapopulation connectivity

    NASA Astrophysics Data System (ADS)

    Zhang, Xinzhong; Haidvogel, Dale; Munroe, Daphne; Powell, Eric N.; Klinck, John; Mann, Roger; Castruccio, Frederic S.

    2015-02-01

    To study the primary larval transport pathways and inter-population connectivity patterns of the Atlantic surfclam, Spisula solidissima, a coupled modeling system combining a physical circulation model of the Middle Atlantic Bight (MAB), Georges Bank (GBK) and the Gulf of Maine (GoM), and an individual-based surfclam larval model was implemented, validated and applied. Model validation shows that the model can reproduce the observed physical circulation patterns and surface and bottom water temperature, and recreates the observed distributions of surfclam larvae during upwelling and downwelling events. The model results show a typical along-shore connectivity pattern from the northeast to the southwest among the surfclam populations distributed from Georges Bank west and south along the MAB shelf. Continuous surfclam larval input into regions off Delmarva (DMV) and New Jersey (NJ) suggests that insufficient larval supply is unlikely to be the factor causing the failure of the population to recover after the observed decline of the surfclam populations in DMV and NJ from 1997 to 2005. The GBK surfclam population is relatively more isolated than populations to the west and south in the MAB; model results suggest substantial inter-population connectivity from southern New England to the Delmarva region. Simulated surfclam larvae generally drift for over one hundred kilometers along the shelf, but the distance traveled is highly variable in space and over time. Surfclam larval growth and transport are strongly impacted by the physical environment. This suggests the need to further examine how the interaction between environment, behavior, and physiology affects inter-population connectivity. Larval vertical swimming and sinking behaviors have a significant net effect of increasing larval drifting distances when compared with a purely passive model, confirming the need to include larval behavior.

  14. Circulation constrains the evolution of larval development modes and life histories in the coastal ocean.

    PubMed

    Pringle, James M; Byers, James E; Pappalardo, Paula; Wares, John P; Marshall, Dustin

    2014-04-01

    The evolutionary pressures that drive long larval planktonic durations in some coastal marine organisms, while allowing direct development in others, have been vigorously debated. We introduce into the argument the asymmetric dispersal of larvae by coastal currents and find that the strength of the currents helps determine which dispersal strategies are evolutionarily stable. In a spatially and temporally uniform coastal ocean of finite extent, direct development is always evolutionarily stable. For passively drifting larvae, long planktonic durations are stable when the ratio of mean to fluctuating currents is small and the rate at which larvae increase in size in the plankton is greater than the mortality rate (both in units of per time). However, larval behavior that reduces downstream larval dispersal for a given time in plankton will be selected for, consistent with widespread observations of behaviors that reduce dispersal of marine larvae. Larvae with long planktonic durations are shown to be favored not for the additional dispersal they allow, but for the additional fecundity that larval feeding in the plankton enables. We analyzed the spatial distribution of larval life histories in a large database of coastal marine benthic invertebrates and documented a link between ocean circulation and the frequency of planktotrophy in the coastal ocean. The spatial variation in the frequency of species with planktotrophic larvae is largely consistent with our theory; increases in mean currents lead to a decrease in the fraction of species with planktotrophic larvae over a broad range of temperatures. PMID:24933820

  15. Exploring Larval Development and Applications in Marine Fish Aquaculture Using Pink Snapper Embryos

    ERIC Educational Resources Information Center

    Tamaru, Clyde; Haverkort-Yeh, Roxanne D.; Gorospe, Kelvin D.; Rivera, Malia Ana J.

    2014-01-01

    This biology investigation on "Pristipomoides filamentosus" larval development, survival, and aquaculture research was developed with three educational objectives: to provide high school students with (1) a scientific background on the biology and science of fisheries as well as overfishing, its consequences, and possible mitigations;…

  16. Worker honey bee ovary development: seasonal variation and the influence of larval and adult nutrition.

    PubMed

    Hoover, Shelley E R; Higo, Heather A; Winston, Mark L

    2006-01-01

    We examined the effect of larval and adult nutrition on worker honey bee (Apis mellifera L.) ovary development. Workers were fed high or low-pollen diets as larvae, and high or low-protein diets as adults. Workers fed low-protein diets at both life stages had the lowest levels of ovary development, followed by those fed high-protein diets as larvae and low- quality diets as adults, and then those fed diets poor in protein as larvae but high as adults. Workers fed high-protein diets at both life stages had the highest levels of ovary development. The increases in ovary development due to improved dietary protein in the larval and adult life stages were additive. Adult diet also had an effect on body mass. The results demonstrate that both carry-over of larval reserves and nutrients acquired in the adult life stage are important to ovary development in worker honey bees. Carry-over from larval development, however, appears to be less important to adult fecundity than is adult nutrition. Seasonal trends in worker ovary development and mass were examined throughout the brood rearing season. Worker ovary development was lowest in spring, highest in mid-summer, and intermediate in fall. PMID:16228242

  17. A note on the population genetic consequences of delayed larval development in insects.

    PubMed

    de Salles, Marcos Mattoso; Otto, Paulo A

    2013-09-01

    Observations by Dobzhansky's group in the 1940s suggesting that the presence of recessive genotypes could account for lower larval developmental rates in Drosophila melanogaster were not confirmed at the time and all subsequent investigations on this subject focused on the analysis of ecological models based on competition among pre-adult individuals. However, a paper published in this journal in 1991 eventually confirmed the finding made by Dobzhansky and his co-workers. In this report, we provide a theoretical analysis of the population genetic effects of a delay in the rate of larval development produced by such a genetic mechanism. PMID:24130452

  18. Evolution and development of gastropod larval shell morphology: experimental evidence for mechanical defense and repair.

    PubMed

    Hickman, C S

    2001-01-01

    The structural diversity of gastropod veliger larvae offers an instructive counterpoint to the view of larval forms as conservative archetypes. Larval structure, function, and development are fine-tuned for survival in the plankton. Accordingly, the study of larval adaptation provides an important perspective for evolutionary-developmental biology as an integrated science. Patterns of breakage and repair in the field, as well as patterns of breakage in arranged encounters with zooplankton under laboratory conditions, are two powerful sources of data on the adaptive significance of morphological and microsculptural features of the gastropod larval shell. Shells of the planktonic veliger larvae of the caenogastropod Nassarius paupertus [GOULD] preserve multiple repaired breaks, attributed to unsuccessful zooplankton predators. In culture, larvae isolated from concentrated zooplankton samples rapidly repaired broken apertural margins and restored the "ideal" apertural form, in which an elaborate projection or "beak" covers the head of the swimming veliger. When individuals with repaired apertures were reintroduced to a concentrated mixture of potential zooplankton predators, the repaired margins were rapidly chipped and broken back. The projecting beak of the larval shell is the first line of mechanical defense, covering the larval head and mouth and potentially the most vulnerable part of the shell to breakage. Patterns of mechanical failure show that spiral ridges do reinforce the beak and retard breakage. The capacity for rapid shell repair and regeneration, and the evolution of features that resist or retard mechanical damage, may play a more prominent role than previously thought in enhancing the ability of larvae to survive in the plankton. PMID:11256430

  19. INFLUENCE OF AN INSECT GROWTH REGULATOR ON THE LARVAL DEVELOPMENT OF THE MUD CRAB RHITHOPANOPEUS HARRISSII

    EPA Science Inventory

    Effects of the juvenile hormone analogue (S)-methoprene on the larval development and survival of the estuarine mud crab hithropanopeus harrisii were examined in the laboratory. rablarvae continuously exposed to 1000 ug (S)-methoprene/liter did not survive beyond zoeal stage I. i...

  20. Development of a larval diet for the South American fruit fly Anastrepha fraterculus (Diptera:Tephritidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mass-rearing protocols must be developed. In particular, a cost-effective larval diet, to implement the sterile insect technique against Anastrepha fratercculus (Wiedemann). The key elements of this diet are the optimal nutrients and their concentrations, diet supports or bulking agents, and the pH ...

  1. Role of Bacillus thuringiensis Cry1 δ Endotoxin Binding in Determining Potency during Lepidopteran Larval Development

    PubMed Central

    Gilliland, Androulla; Chambers, Catherine E.; Bone, Eileen J.; Ellar, David J.

    2002-01-01

    Five economically important crop pests, Manduca sexta, Pieris brassicae, Mamestra brassicae, Spodoptera exigua, and Agrotis ipsilon, were tested at two stages of larval development for susceptibility to Bacillus thuringiensis toxins Cry1Ac, Cry1Ca, Cry1J, and Cry1Ba. Bioassay results for M. sexta showed that resistance to all four Cry toxins increased from the neonate stage to the third-instar stage; the increase in resistance was most dramatic for Cry1Ac, the potency of which decreased 37-fold. More subtle increases in resistance during larval development were seen in M. brassicae for Cry1Ca and in P. brassicae for Cry1Ac and Cry1J. By contrast, the sensitivity of S. exigua did not change during development. At both larval stages, A. ipsilon was resistant to all four toxins. Because aminopeptidase N (APN) is a putative Cry1 toxin binding protein, APN activity was measured in neonate and third-instar brush border membrane vesicles (BBMV). With the exception of S. exigua, APN activity was found to be significantly lower in neonates than in third-instar larvae and thus inversely correlated with increased resistance during larval development. The binding characteristics of iodinated Cry1 toxins were determined for neonate and third-instar BBMV. In M. sexta, the increased resistance to Cry1Ac and Cry1Ba during larval development was positively correlated with fewer binding sites in third-instar BBMV than in neonate BBMV. The other species-instar-toxin combinations did not reveal positive correlations between potency and binding characteristics. The correlation between binding and potency was inconsistent for the species-instar-toxin combinations used in this study, reaffirming the complex mode of action of Cry1 toxins. PMID:11916662

  2. Development of the Acoustically Evoked Behavioral Response in Larval Plainfin Midshipman Fish, Porichthys notatus

    PubMed Central

    Alderks, Peter W.; Sisneros, Joseph A.

    2013-01-01

    The ontogeny of hearing in fishes has become a major interest among bioacoustics researchers studying fish behavior and sensory ecology. Most fish begin to detect acoustic stimuli during the larval stage which can be important for navigation, predator avoidance and settlement, however relatively little is known about the hearing capabilities of larval fishes. We characterized the acoustically evoked behavioral response (AEBR) in the plainfin midshipman fish, Porichthys notatus, and used this innate startle-like response to characterize this species' auditory capability during larval development. Age and size of larval midshipman were highly correlated (r2 = 0.92). The AEBR was first observed in larvae at 1.4 cm TL. At a size ≥1.8 cm TL, all larvae responded to a broadband stimulus of 154 dB re1 µPa or −15.2 dB re 1 g (z-axis). Lowest AEBR thresholds were 140–150 dB re 1 µPa or −33 to −23 dB re 1 g for frequencies below 225 Hz. Larval fish with size ranges of 1.9–2.4 cm TL had significantly lower best evoked frequencies than the other tested size groups. We also investigated the development of the lateral line organ and its function in mediating the AEBR. The lateral line organ is likely involved in mediating the AEBR but not necessary to evoke the startle-like response. The midshipman auditory and lateral line systems are functional during early development when the larvae are in the nest and the auditory system appears to have similar tuning characteristics throughout all life history stages. PMID:24340003

  3. Cell position during larval development affects postdiapause development in Megachile rotundata (Hymenoptera: Megachilidae).

    PubMed

    Yocum, George D; Rinehart, Joseph P; Kemp, William P

    2014-08-01

    Megachile rotundata (F.) (Hymenoptera: Megachilidae) is the primary pollinator of alfalfa in the northwestern United States and western Canada and provides pollination services for onion, carrot, hybrid canola, various legumes, and other specialty crops. M. rotundata females are gregarious, nest in cavities either naturally occurring or in artificial nesting blocks, where they construct a linear series of brood cells. Because of the physical layout of the nest, the age of the larvae within the nest and the microenvironment the individual larvae experience will vary. These interacting factors along with other maternal inputs affect the resulting phenotypes of the nest mates. To further our understanding of in-nest physiology, gender and developmental rates were examined in relationship to cell position within the nest. Eighty-two percent of the females were located within the first three cells, those furthest from the nest entrance. For those individuals developing in cells located in the deepest half of the nest, the sex of the previous bee had a significant effect on the female decision of the gender of the following nest mate. Removing the prepupae from the nest and rearing them under identical conditions demonstrated that position within the nest during larval development had a significant effect on the postdiapause developmental rates, with males whose larval development occurred deeper in the nest developing more slowly than those toward the entrance. No positional effect on postdiapause developmental rates was noted for the females. The cell position effect on male postdiapause developmental rate demonstrates that postdiapause development is not a rigid physiological mechanism uniform in all individuals, but is a dynamic plastic process shaped by past environmental conditions. PMID:24914676

  4. Larval development and metamorphosis in Pleurobranchaea maculata, with a review of development in the notaspidea (Opisthobranchia).

    PubMed

    Gibson, Glenys D

    2003-10-01

    Pleurobranchaea maculata is a carnivorous notaspidean that is common in New Zealand. This species produces small eggs (diameter 100 microm) and planktotrophic veligers that hatch in 8 d and are planktonic for 3 weeks before settling on biofilmed surfaces (14 degrees C). Larval development is known in detail for only two other notaspidean species, P. japonica and Berthellina citrina. In all three species of pleurobranchids, mantle and shell growth show striking differences from veligers of other opisthobranch taxa. In young veligers of pleurobranchids, the shell is overgrown by the mantle, new shell is added by cells other than those of the mantle fold, and an operculum does not form. Thus some "adult" traits (e.g., notum differentiation, mechanism of shell growth, lack of operculum) are expressed early in larval development. This suggests that apomorphies characteristic of adult pleurobranchids evolved through heterochrony, with expression in larvae of traits typical of adults of other clades. The protoconch is dissolved post-settlement and not cast off as occurs in other opisthobranch orders, indicating that shell loss is apomorphic. P. maculata veligers are atypical of opisthobranchs in having a field of highly folded cells on the lower velar surface, a mouth that is posterior to the metatroch, and a richly glandular, possibly chemodefensive mantle. These data indicate that notaspidean larvae are highly derived in terms of the novel traits and the timing of morphogenic events. Phylogenetic analysis must consider embryological origins before assuming homology, as morphological similarities (e.g., shell loss) may have developed through distinct mechanisms. PMID:14583510

  5. Warmer winters reduce frog fecundity and shift breeding phenology, which consequently alters larval development and metamorphic timing.

    PubMed

    Benard, Michael F

    2015-03-01

    One widely documented phenological response to climate change is the earlier occurrence of spring-breeding events. While such climate change-driven shifts in phenology are common, their consequences for individuals and populations have rarely been investigated. I addressed this gap in our knowledge by using a multi-year observational study of six wood frog (Rana sylvatica) populations near the southern edge of their range. I tested first if winter temperature or precipitation affected the date of breeding and female fecundity, and second if timing of breeding affected subsequent larval development rate, mass at metamorphosis, date of metamorphosis, and survival. Warmer winters were associated with earlier breeding but reduced female fecundity. Winter precipitation did not affect breeding date, but was positively associated with female fecundity. There was no association between earlier breeding and larval survival or mass at metamorphosis, but earlier breeding was associated with delayed larval development. The delay in larval development was explained through a counterintuitive correlation between breeding date and temperature during larval development. Warmer winters led to earlier breeding, which in turn was associated with cooler post-breeding temperatures that slowed larval development. The delay in larval development did not fully compensate for the earlier breeding, such that for every 2 days earlier that breeding took place, the average date of metamorphosis was 1 day earlier. Other studies have found that earlier metamorphosis is associated with increased postmetamorphic growth and survival, suggesting that earlier breeding has beneficial effects on wood frog populations. PMID:25263760

  6. Energy metabolism during larval development of green and white abalone, Haliotis fulgens and H. sorenseni.

    PubMed

    Moran, Amy L; Manahan, Donal T

    2003-06-01

    An understanding of the biochemical and physiological energetics of lecithotrophic development is useful for interpreting patterns of larval development, dispersal potential, and life-history evolution. This study investigated the metabolic rates and use of biochemical reserves in two species of abalone, Haliotis fulgens (the green abalone) and H. sorenseni (the white abalone). Larvae of H. fulgens utilized triacylglycerol as a primary source of endogenous energy reserves for development ( approximately 50% depletion from egg to metamorphic competence). Amounts of phospholipid remained constant, and protein dropped by about 30%. After embryogenesis, larvae of H. fulgens had oxygen consumption rates of 81.7 +/- 5.9 (SE) pmol larva(-1) h(-1) at 15 degrees C through subsequent development. The loss of biochemical reserves fully met the needs of metabolism, as measured by oxygen consumption. Larvae of H. sorenseni were examined during later larval development and were metabolically and biochemically similar to H. fulgens larvae at a comparable stage. Metabolic rates of both species were very similar to previous data for a congener, H. rufescens, suggesting that larval metabolism and energy utilization may be conserved among closely related species that also share similar developmental morphology and feeding modes. PMID:12807704

  7. Influence of resources on Hermetia illucens (Diptera: Stratiomyidae) larval development.

    PubMed

    Nguyen, Trinh T X; Tomberlin, Jeffery K; Vanlaerhoven, Sherah

    2013-07-01

    Arthropod development can be used to determine the time of colonization of human remains to infer a minimum postmortem interval. The black soldier fly, Hermetia illucens L. (Diptera. Stratiomyidae) is native to North America and is unique in that its larvae can consume a wide range of decomposing organic material, including carrion. Larvae development was observed on six resources: control poultry feed, liver, manure, kitchen waste, fruits and vegetables, and fish rendering. Larvae fed manure were shorter, weighed less, and took longer to develop. Kitchen waste produced longer and heavier larvae, whereas larvae fed fish had almost 100% mortality. Black soldier flies can colonize human remains, which in many instances can coincide with food and organic wastes. Therefore, it is necessary to understand black soldier fly development on different food resources other than carrion tissue to properly estimate their age when recovered from human remains. PMID:23926790

  8. Larval Development of Two N. E. Pacific Pilidiophoran Nemerteans (Heteronemertea; Lineidae).

    PubMed

    Hiebert, Terra C; Maslakova, Svetlana A

    2015-12-01

    Unique to the phylum Nemertea, the pilidium is an unmistakable planktonic larva found in one group of nemerteans, the Pilidiophora. Inside the pilidium, the juvenile develops from a series of epidermal invaginations in the larval body, called imaginal discs. The discs grow and fuse around the larval gut over the course of weeks to months in the plankton. Once complete, the juvenile breaks free from the larval body in a catastrophic metamorphosis, and often devours the larva as its first meal. One third of nemertean species are expected to produce a pilidium, but the larvae are known for very few species; development from fertilization to metamorphosis has been described in only one species, Micrura alaskensis. Known pilidia include both planktotrophic and lecithotrophic forms, and otherwise exhibit great morphological diversity. Here, we describe the complete development in two lineiform species that are common to the northeast Pacific coast, Micrura wilsoni and Lineus sp. "red." Both species possess typical, cap-shaped planktotrophic pilidia, and the order of emergence of imaginal discs is similar to that which is described in M. alaskensis. The pilidium of Lineus sp. "red" resembles pilidia of several other species, such as Lineus flavescens, and potentially characterizes a pilidiophoran clade. M. wilsoni has relatively transparent oocytes and a pilidium with what appears to be a unique pattern of pigmentation. The adults of both species are more commonly observed in intertidal zones than their larvae are in the plankton. PMID:26695825

  9. Imaging neural development in embryonic and larval sea urchins.

    PubMed

    Krupke, Oliver; Yaguchi, Shunsuke; Yaguchi, Junko; Burke, Robert D

    2014-01-01

    Imaging is a critical tool in neuroscience, and our understanding of the structure and function of sea urchin nervous systems owes much to this approach. In particular, studies of neural development have been facilitated by methods that enable the accurate identification of specific types of neurons. Here we describe methods that have been successfully employed to study neural development in sea urchin embryos. Altering gene expression in part of an embryo is facilitated by injection of reagents into individual blastomeres, which enables studies of cell autonomous effects and single embryo rescue experiments. The simultaneous localization of an in situ RNA hybridization probe and a cell type specific antigen has enabled studies of gene expression in specific types of neurons. Fixatives and antibodies can be capricious; thus, we provide data on preservation of antigens with commonly used fixatives and buffers. PMID:24567212

  10. Individual and mixture effects of selected pharmaceuticals on larval development of the estuarine shrimp Palaemon longirostris.

    PubMed

    González-Ortegón, Enrique; Blasco, Julian; Nieto, Elena; Hampel, Miriam; Le Vay, Lewis; Giménez, Luis

    2016-01-01

    Few ecotoxicological studies incorporate within the experimental design environmental variability and mixture effects when assessing the impact of pollutants on organisms. We have studied the combined effects of selected pharmaceutical compounds and environmental variability in terms of salinity and temperature on survival, development and body mass of larvae of the estuarine shrimp Palaemon longirostris. Drug residues found in coastal waters occur as mixture, and the evaluation of combined effects of simultaneously occurring compounds is indispensable for their environmental risk assessment. All larval stages of P. longirostris were exposed to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium (DS: 40 and 750 μg L(-1)), the lipid regulator clofibric acid (CA: 17 and 361 μg L(-1)) and the fungicide clotrimazole (CLZ: 0.14 and 4 μg L(-1)). We observed no effect on larval survival of P. longirostris with the tested pharmaceuticals. However, and in contrast to previous studies on larvae of the related marine species Palaemon serratus, CA affected development through an increase in intermoult duration and reduced growth without affecting larval body mass. These developmental effects in P. longirostris larvae were similar to those observed in the mixture of DS and CA confirming the toxic effects of CA. In the case of CLZ, its effects were similar to those observed previously in P. serratus: high doses affected development altering intermoult duration, tended to reduce the number of larval instars and decreased significantly the growth rate. This study suggests that an inter-specific life histories approach should be taken into account to assess the effect of emergent compounds in coastal waters. PMID:26163379

  11. UV wavelengths experienced during development affect larval newt visual sensitivity and predation efficiency.

    PubMed

    Martin, Mélissa; Théry, Marc; Rodgers, Gwendolen; Goven, Delphine; Sourice, Stéphane; Mège, Pascal; Secondi, Jean

    2016-02-01

    We experimentally investigated the influence of developmental plasticity of ultraviolet (UV) visual sensitivity on predation efficiency of the larval smooth newt, Lissotriton vulgaris. We quantified expression of SWS1 opsin gene (UV-sensitive protein of photoreceptor cells) in the retinas of individuals who had developed in the presence (UV+) or absence (UV-) of UV light (developmental treatments), and tested their predation efficiency under UV+ and UV- light (testing treatments). We found that both SWS1 opsin expression and predation efficiency were significantly reduced in the UV- developmental group. Larvae in the UV- testing environment displayed consistently lower predation efficiency regardless of their developmental treatment. These results prove for the first time, we believe, functional UV vision and developmental plasticity of UV sensitivity in an amphibian at the larval stage. They also demonstrate that UV wavelengths enhance predation efficiency and suggest that the magnitude of the behavioural response depends on retinal properties induced by the developmental lighting environment. PMID:26843556

  12. Spawning, fertilization, and larval development of Potamocorbula amurensis (Mollusca: Bivalvia) from San Francisco Bay, California

    USGS Publications Warehouse

    Nicolini, M.H.; Penry, D.L.

    2000-01-01

    In Potamocorbula amurensis time for development to the straight-hinge larval stage is 48 hr at 15??C. Potamocorbula amurensis settles at a shell length of approximately 135 ??m 17 to 19 days after fertilization. Our observations of timing of larval devdlopment in P. amurensis support the hypothesis of earlier workers that its route of initial introduction to San Francisco Bay was as veliger larvae transported in ballast water by trans-Pacific cargo ships. The length of the larval period of P. amurensis relative to water mass residence times in San Francisco Bay suggests that it is sufficient to allow substantial dispersal from North Bay to South Bay populations in concordance with previous observations that genetic differentiation among populations of P. amurensis in San Francisco Bay is low. Potamocorbula amurensis is markedly euryhaline at all stages of development. Spawning and fertilization can occur at salinities from 5 to 25 psu, and eggs and sperms can each tolerance at least a 10-psu step increase or decrease in salinity. Embryos that are 2 hr old can tolerate the same range of salinities from (10 to 30 psu), and by the time they are 24 hr old they can tolerate the same range of salinities (2 to 30 psu) that adult clams can. The ability of P. amurensis larvae to tolerate substantial step changes in salinity suggests a strong potential to survive incomplete oceanic exchanges of ballast water and subsequent discharge into receiving waters across a broad range of salinities.

  13. Juvenile Green Frog (Rana clamitans) Predatory Ability not Affected by Exposure to Carbaryl at Different Times During Larval Development

    PubMed Central

    Davis, Melanie J.; Kleinhenz, Peter; Boone, Michelle D.

    2011-01-01

    Larval exposure to pesticides can occur at different times during development, and can negatively impact amphibian fitness. We examined the effects of larval green frog (Rana clamitans) exposure to carbaryl at 2, 4, 8, or 16 weeks of development on juvenile predatory ability. We did not find evidence that predatory ability was affected by exposure to carbaryl, which suggests that carbaryl does not have latent effects on the predatory performance of green frogs in subsequent life stages. PMID:21462236

  14. CCDC-55 is required for larval development and distal tip cell migration in Caenorhabditis elegans.

    PubMed

    Kovacevic, Ismar; Ho, Richard; Cram, Erin J

    2012-01-01

    The Caenorhabditis elegans distal tip cells (DTCs) are an in vivo model for the study of developmentally regulated cell migration. In this study, we characterize a novel role for CCDC-55, a conserved coiled-coil domain containing protein, in DTC migration and larval development in C. elegans. Although animals homozygous for a probable null allele, ccdc-55(ok2851), display an early larval arrest, RNAi depletion experiments allow the analysis of later phenotypes and suggest that CCDC-55 is needed within the DTC for migration to cease at the end of larval morphogenesis. The ccdc-55 gene is found in an operon with rnf-121 and rnf-5, E3 ubiquitin ligases that target cell migration genes such as the β-integrin PAT-3. Genetic interaction studies using RNAi depletion and the deletion alleles rnf-121(ok848) and rnf-5(tm794) indicate that CCDC-55 and the RNF genes act at least partially in parallel to promote termination of cell migration in the adult DTC. PMID:22285439

  15. CCDC-55 is required for larval development and distal tip cell migration in C. elegans

    PubMed Central

    Kovacevic, Ismar; Ho, Richard; Cram, Erin J.

    2012-01-01

    The C. elegans distal tip cells (DTCs) are an in vivo model for the study of developmentally regulated cell migration. In this study we characterize a novel role for CCDC-55, a conserved coiled-coil domain containing protein, in DTC migration and larval development in C. elegans. Although animals homozygous for a probable null allele, ccdc-55(ok2851), display an early larval arrest, RNAi depletion experiments allow the analysis of later phenotypes and suggest that CCDC-55 is needed within the DTC for migration to cease at the end of larval morphogenesis. The ccdc-55 gene is found in an operon with rnf-121 and rnf-5, E3 ubiquitin ligases that target cell migration genes such as the β-integrin PAT-3. Genetic interaction studies using RNAi depletion and the deletion alleles rnf-121(ok848) and rnf-5(tm794) indicate that CCDC-55 and the RNF genes act at least partially in parallel to promote termination of cell migration in the adult DTC. PMID:22285439

  16. Artificial substrates for oviposition and larval development of the pepper weevil (Coleoptera: Curculionidae).

    PubMed

    Addesso, K M; McAuslane, H J; Stansly, P A; Slansky, F; Schuster, D J

    2009-02-01

    The pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae), is a major pest of cultivated peppers (Capsicum spp.) and other cultivated and wild species within the family Solanaceae. Laboratory study of this insect, as well as its biological control agents, will be greatly facilitated by an artificial rearing system that does not rely on pepper fruit. An egg collection method and amendments to a standard larval diet were investigated for use in the rearing of this weevil. Spherical sachets made of Parafilm or netting enclosing leaves of pepper, American black nightshade, eggplant, tomato, potato, and jasmine tobacco induced oviposition. Tomato, potato, and jasmine tobacco leaves were accepted despite the fact that these are not oviposition hosts for pepper weevils in the wild. A standard larval diet formula was modified in an attempt to improve egg hatch, larval survival, developmental time, and adult mass. The diet formula was modified with the addition of freeze-dried jalapeño pepper powder, an additional lipid source, alternate protein sources, and the removal of methyl paraben. None of the aforementioned treatments resulted in a significant improvement over the standard diet. Egg hatch was greater when eggs were incubated on moist paper towels rather than in diet; thus, placement of neonates rather than eggs into diet improved production of adults. Suggestions for more efficient rearing of weevils on the currently available diet and future directions for the development of an artificial rearing system for pepper weevil are discussed. PMID:19253644

  17. amontillado, the Drosophila homolog of the prohormone processing protease PC2, is required during embryogenesis and early larval development.

    PubMed Central

    Rayburn, Lowell Y M; Gooding, Holly C; Choksi, Semil P; Maloney, Dhea; Kidd, Ambrose R; Siekhaus, Daria E; Bender, Michael

    2003-01-01

    Biosynthesis of most peptide hormones and neuropeptides requires proteolytic excision of the active peptide from inactive proprotein precursors, an activity carried out by subtilisin-like proprotein convertases (SPCs) in constitutive or regulated secretory pathways. The Drosophila amontillado (amon) gene encodes a homolog of the mammalian PC2 protein, an SPC that functions in the regulated secretory pathway in neuroendocrine tissues. We have identified amon mutants by isolating ethylmethanesulfonate (EMS)-induced lethal and visible mutations that define two complementation groups in the amon interval at 97D1 of the third chromosome. DNA sequencing identified the amon complementation group and the DNA sequence change for each of the nine amon alleles isolated. amon mutants display partial embryonic lethality, are defective in larval growth, and arrest during the first to second instar larval molt. Mutant larvae can be rescued by heat-shock-induced expression of the amon protein. Rescued larvae arrest at the subsequent larval molt, suggesting that amon is also required for the second to third instar larval molt. Our data indicate that the amon proprotein convertase is required during embryogenesis and larval development in Drosophila and support the hypothesis that AMON acts to proteolytically process peptide hormones that regulate hatching, larval growth, and larval ecdysis. PMID:12586710

  18. Suitability of monotypic and mixed diets for Anopheles hermsi larval development.

    PubMed

    Beasley, Donald A; Walton, William E

    2016-06-01

    The developmental time and survival to eclosion of Anopheles hermsi Barr & Guptavanij fed monotypic and mixed diets of ten food types were examined in laboratory studies. Larvae fed monotypic diets containing animal detritus (freeze-dried rotifers, freeze-dried Daphnia pulicaria, and TetraMin® fish food flakes) and the mixotrophic protistan Cryptomonas ovata developed faster and survived better than larvae that were fed other monotypic diets. Survival to adulthood of larvae fed several concentrations of the diatom Planothidium (=Achnanthes) lanceolatum was poor (<13%) and larval development time was approximately twice that of larvae fed TetraMin® fish food flakes, the standard laboratory diet. Larvae fed monotypic diets containing prokaryotes (bacteria [Bacillus cereus] and cyanobacteria [Oscillatoria prolifera]) and brewer's yeast (Saccharomyces cerevisiae) failed to survive beyond the 1(st) and 2(nd) instar, respectively. Larvae fed only chlorophytes, single-celled Chlamydomonas reinhardtii and filamentous Spirogyra communis, failed to complete larval development, regardless of the concentration tested. Cohorts fed a combination of food types (mixed diets) usually developed better than cohorts fed monotypic diets. Food types that failed to support complete development when fed alone often facilitated development to adulthood when fed in combination with food types containing >1% C20 polyunsaturated fatty acids as total fat, but regardless of essential fatty acid content, algae that produced mucilage and filaments that sank out of the feeding zone were poor quality diets. PMID:27232128

  19. Larval spicules, cilia, and symmetry as remnants of indirect development in the direct developing sea urchin Heliocidaris erythrogramma.

    PubMed

    Emlet, R B

    1995-02-01

    Nonfeeding larvae of the echinoid Heliocidaris erythrogramma were raised in culture and examined for expression of a larval skeleton and for the arrangement of the ciliated band. Opaque larvae were fixed, cleared, and examined under polarized light for evidence of calcification. By 35 hr after fertilization (at 22 degrees C), a pair of triradiate spicules was present at the posterior end of the larvae. Each member of this pair formed a fenestrated spicule as it grew laterally. This pair and another pair which formed subsequently, were arranged across a plane of bilateral symmetry orthagonal to the juvenile oral aboral axis. These paired larval spicules can be identified as reduced expressions of postoral and posterodorsal rods found in plutei, and their expression indicates that the juvenile rudiment of H. erythrogramma forms on the left side and that larval body axes are conserved in this modified larva. By 44 hr the ciliated band formed as an incomplete transverse loop of three segments at the posterior end and on the dorsal surface of the ovoid larva. Cilia in these segments grew to lengths of 45-50 microns, longer than other swimming and feeding cilia reported for echinoderm larvae. Band segments are interpreted as expressions of epaulettes (specialized swimming bands) rather than the feeding ciliated band of the pluteus. The ciliated band segments and the larval spicules are both bilaterally symmetrical with respect to the same plane and indicate conserved larval bilateral symmetry despite the major asymmetry of the fates of cells on either side of this plane in their contribution to juvenile development. PMID:7875367

  20. Urbanization Increases Aedes albopictus Larval Habitats and Accelerates Mosquito Development and Survivorship

    PubMed Central

    Li, Yiji; Kamara, Fatmata; Zhou, Guofa; Puthiyakunnon, Santhosh; Li, Chunyuan; Liu, Yanxia; Zhou, Yanhe; Yao, Lijie; Yan, Guiyun; Chen, Xiao-Guang

    2014-01-01

    Introduction Aedes albopictus is a very invasive and aggressive insect vector that causes outbreaks of dengue fever, chikungunya disease, and yellow fever in many countries. Vector ecology and disease epidemiology are strongly affected by environmental changes. Urbanization is a worldwide trend and is one of the most ecologically modifying phenomena. The purpose of this study is to determine how environmental changes due to urbanization affect the ecology of Aedes albopictus. Methods Aquatic habitats and Aedes albopictus larval population surveys were conducted from May to November 2013 in three areas representing rural, suburban, and urban settings in Guangzhou, China. Ae. albopictus adults were collected monthly using BG-Sentinel traps. Ae. albopictus larva and adult life-table experiments were conducted with 20 replicates in each of the three study areas. Results The urban area had the highest and the rural area had the lowest number of aquatic habitats that tested positive for Ae. albopictus larvae. Densities in the larval stages varied among the areas, but the urban area had almost two-fold higher densities in pupae and three-fold higher in adult populations compared with the suburban and rural areas. Larvae developed faster and the adult emergence rate was higher in the urban area than in suburban and rural areas. The survival time of adult mosquitoes was also longer in the urban area than it was in suburban and rural areas. Study regions, surface area, water depth, water clearance, surface type, and canopy coverage were important factors associated with the presence of Ae. albopictus larvae. Conclusions Urbanization substantially increased the density, larval development rate, and adult survival time of Ae. albopictus, which in turn potentially increased the vector capacity, and therefore, disease transmissibility. Mosquito ecology and its correlation with dengue virus transmission should be compared in different environmental settings. PMID:25393814

  1. Effect of Two Oil Dispersants on Larval Grass Shrimp (Palaemonetes pugio) Development.

    NASA Astrophysics Data System (ADS)

    Betancourt, P.; Key, P. B.; Chung, K. W.; DeLorenzo, M. E.

    2015-12-01

    The study focused on the effects that two oil dispersants, Corexit® EC9500A and Finasol® OSR52, have on the development of larval grass shrimp, (Palaemonetes pugio). The hypothesis was that Finasol would have a greater effect on larval grass shrimp development than Corexit. The experiment was conducted using 300 grass shrimp larvae that were 24 hours old. Each larva was exposed individually. In total, five sub-lethal concentrations were tested for each dispersant (control, 1.25, 2.50, 5.0,10.0 mg/L). The larvae were exposed for five days then transferred to clean seawater until metamorphosis into the juvenile stage. Key data measurements recorded included number of days to become juveniles, number of instars, length, dry weight, and mortality. Data from exposed shrimp was compared to the results of the control for each dispersant concentration. Corexit and Finasol exposure treatments of 5 mg/L and 10 mg/L showed significantly higher values for number of days and number of instars to reach juvenile status than values obtained from unexposed, control shrimp. Overall, mortality was higher in the Finasol treatments but the two dispersants did not respond significantly different from one another. Future studies are needed to determine the long term effects of dispersant exposure on all grass shrimp life stages and how any dispersant exposure impacts grass shrimp populations. Grass shrimp serve as excellent toxicity indicators of estuaries, and further studies will help to develop better oil spill mitigation techniques.

  2. Growth and development of larval green frogs (Rana clamitans) exposed to multiple doses of an insecticide

    USGS Publications Warehouse

    Boone, M.D.; Bridges, C.M.; Rothermel, B.B.

    2001-01-01

    Our objective was to determine how green frogs (Rana clamitans) are affected by multiple exposures to a sublethal level of the carbamate insecticide, carbaryl, in outdoor ponds. Tadpoles were added to 1,000-1 ponds at a low or high density which were exposed to carbaryl 0, 1, 2, or 3 times. Length of the larval period, mass, developmental stage, tadpole survival, and proportion metamorphosed were used to determine treatment effects. The frequency of dosing affected the proportion of green frogs that reached metamorphosis and the developmental stage of tadpoles. Generally, exposure to carbaryl increased rates of metamorphosis and development. The effect of the frequency of carbaryl exposure on development varied with the density treatment; the majority of metamorphs and the most developed tadpoles came from high-density ponds exposed to carbaryl 3 times. This interaction suggests that exposure to carbaryl later in the larval period stimulated metamorphosis, directly or indirectly, under high-density conditions. Our study indicates that exposure to a contaminant can lead to early initiation of metamorphosis and that natural biotic factors can mediate the effects of a contaminant in the environment.

  3. Aspects of Embryonic and Larval Development in Bighead Carp Hypophthalmichthys nobilis and Silver Carp Hypophthalmichthys molitrix

    PubMed Central

    George, Amy E.; Chapman, Duane C.

    2013-01-01

    As bighead carp Hypophthalmichthysnobilis and silver carp H. molitrix (the bigheaded carps) are poised to enter the Laurentian Great Lakes and potentially damage the region’s economically important fishery, information on developmental rates and behaviors of carps is critical to assessing their ability to establish sustainable populations within the Great Lakes basin. In laboratory experiments, the embryonic and larval developmental rates, size, and behaviors of bigheaded carp were tracked at two temperature treatments, one “cold” and one “warm”. Developmental rates were computed using previously described stages of development and the cumulative thermal unit method. Both species have similar thermal requirements, with a minimum developmental temperature for embryonic stages of 12.1° C for silver carp and 12.9° C for bighead carp, and 13.3° C for silver carp larval stages and 13.4° C for bighead carp larval stages. Egg size differed among species and temperature treatments, as egg size was larger in bighead carp, and “warm" temperature treatments. The larvae started robust upwards vertical swimming immediately after hatching, interspersed with intervals of sinking. Vertical swimming tubes were used to measure water column distribution, and ascent and descent rates of vertically swimming fish. Water column distribution and ascent and descent rates changed with ontogeny. Water column distribution also showed some diel periodicity. Developmental rates, size, and behaviors contribute to the drift distance needed to fulfill the early life history requirements of bigheaded carps and can be used in conjunction with transport information to assess invasibility of a river. PMID:23967350

  4. Aspects of embryonic and larval development in bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix

    USGS Publications Warehouse

    George, Amy E.; Chapman, Duane C.

    2013-01-01

    As bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix (the bigheaded carps) are poised to enter the Laurentian Great Lakes and potentially damage the region’s economically important fishery, information on developmental rates and behaviors of carps is critical to assessing their ability to establish sustainable populations within the Great Lakes basin. In laboratory experiments, the embryonic and larval developmental rates, size, and behaviors of bigheaded carp were tracked at two temperature treatments, one “cold” and one “warm”. Developmental rates were computed using previously described stages of development and the cumulative thermal unit method. Both species have similar thermal requirements, with a minimum developmental temperature for embryonic stages of 12.1° C for silver carp and 12.9° C for bighead carp, and 13.3° C for silver carp larval stages and 13.4° C for bighead carp larval stages. Egg size differed among species and temperature treatments, as egg size was larger in bighead carp, and “warm" temperature treatments. The larvae started robust upwards vertical swimming immediately after hatching, interspersed with intervals of sinking. Vertical swimming tubes were used to measure water column distribution, and ascent and descent rates of vertically swimming fish. Water column distribution and ascent and descent rates changed with ontogeny. Water column distribution also showed some diel periodicity. Developmental rates, size, and behaviors contribute to the drift distance needed to fulfill the early life history requirements of bigheaded carps and can be used in conjunction with transport information to assess invasibility of a river.

  5. Effect of condensed tannins on egg hatching and larval development of Trichostrongylus colubriformis in vitro.

    PubMed

    Molan, A L; Waghorn, G C; McNabb, W C

    2002-01-19

    The effects of condensed tannins extracted from seven forages on the viability of the eggs and first stage (L1) larvae of the sheep nematode Trichostrongylus colubriformis were evaluated in in vitro assays. The extracts of condensed tannins were obtained from Lotus pedunculatus (LP), Lotus corniculatus (LC), sulla (Hedysarum coronarium), sainfoin (Onobrychus viciifolia), Dorycnium pentaphylum (DP), Dorycnium rectum (DR) and dock (Rumex obtusifolius). Extracts containing 200 to 500 microg/ml reduced the proportion of eggs that hatched. The larval development assay was used to evaluate the effect of the extracts on the development of either eggs or L1 larvae to L3 infective larvae. Development was allowed to proceed for seven days by which time the larvae in control incubations had reached the infective L3 stage. Extracts containing 200 microg/ml from LP, DP, DR or dock prevented egg development, and only 11, 8 and 2 per cent of the eggs developed to L3 larvae with extracts from LC, sulla and sainfoin, respectively. When the concentration was 400 microg/ml no eggs developed to L3 larvae. The addition of the extracts after hatching also inhibited the development of L1 to L3 larvae; 200 microg/ml extracted from LP, LC, sulla, sainfoin, DP, DR and dock resulted in only 14, 18, 17, 15, 14, 16 and 4 per cent of L1 larvae developing to the L3 stage compared with 85 per cent for controls, and 400 microg/ml further reduced the development of L1 larvae. Statistical analyses showed that when the extracts were added before hatching they were significantly (P<0.001) more effective at inhibiting the larval development than when they were added after hatching. The condensed tannins from dock had the greatest inhibitory effect on egg development followed by the tannins from DR, sainfoin, DP, LP, sulla and LC. PMID:11837588

  6. Embryonic and larval development of the host sea anemones Entacmaea quadricolor and Heteractis crispa.

    PubMed

    Scott, Anna; Harrison, Peter L

    2007-10-01

    Little information is available on the sexual reproductive biology of anemones that provide essential habitat for anemonefish. Here we provide the first information on the surface ultrastructural and morphological changes during development of the embryos and planula larvae of Entacmaea quadricolor and Heteractis crispa, using light and scanning electron microscopy. Newly spawned eggs of E. quadricolor and H. crispa averaged 794 microm and 589 microm diameter, respectively, and were covered by many spires of microvilli that were evenly distributed over the egg surface, except for a single bare patch. Eggs of both species contained abundant zooxanthellae when spawned, indicating vertical transmission of symbionts. Fertilization was external, and the resulting embryos displayed superficial cleavage. As development continued, individual blastomeres became readily distinguishable and a round-to-ovoid blastula was formed, which flattened with further divisions. The edges of the blastula thickened, creating a concave-convex dish-shaped gastrula. The outer margins of the gastrula appeared to roll inward, leading to the formation of an oral pore and a ciliated planula larva. Larval motility and directional movement were first observed 36 h after spawning. E. quadricolor larval survival remained high during the first 4 d after spawning, then decreased rapidly. PMID:17928518

  7. Rearing Tenebrio molitor in BLSS: Dietary fiber affects larval growth, development, and respiration characteristics

    NASA Astrophysics Data System (ADS)

    Li, Leyuan; Stasiak, Michael; Li, Liang; Xie, Beizhen; Fu, Yuming; Gidzinski, Danuta; Dixon, Mike; Liu, Hong

    2016-01-01

    Rearing of yellow mealworm (Tenebrio molitor L.) will provide good animal nutrition for astronauts in a bioregenerative life support system. In this study, growth and biomass conversion data of T. molitor larvae were tested for calculating the stoichiometric equation of its growth. Result of a respiratory quotient test proved the validity of the equation. Fiber had the most reduction in mass during T. molitor‧s consumption, and thus it is speculated that fiber is an important factor affecting larval growth of T. molitor. In order to further confirm this hypothesis and find out a proper feed fiber content, T. molitor larvae were fed on diets with 4 levels of fiber. Larval growth, development and respiration in each group were compared and analyzed. Results showed that crude-fiber content of 5% had a significant promoting effect on larvae in early instars, and is beneficial for pupa eclosion. When fed on feed of 5-10% crude-fiber, larvae in later instars reached optimal levels in growth, development and respiration. Therefore, we suggest that crude fiber content in feed can be controlled within 5-10%, and with the consideration of food palatability, a crude fiber of 5% is advisable.

  8. Cloning of aquaporin-1 of the blue crab, Callinectes sapidus: its expression during the larval development in hyposalinity

    PubMed Central

    2012-01-01

    Background Ontogenetic variation in salinity adaptation has been noted for the blue crab, Callinectes sapidus, which uses the export strategy for larval development: females migrate from the estuaries to the coast to spawn, larvae develop in the ocean, and postlarvae (megalopae) colonize estuarine areas. We hypothesized that C. sapidus larvae may be stenohaline and have limited osmoregulatory capacity which compromises their ability to survive in lower salinity waters. We tested this hypothesis using hatchery-raised larvae that were traceable to specific life stages. In addition, we aimed to understand the possible involvement of AQP-1 in salinity adaptation during larval development and during exposure to hyposalinity. Results A full-length cDNA sequence of aquaporin (GenBank JQ970426) was isolated from the hypodermis of the blue crab, C. sapidus, using PCR with degenerate primers and 5′ and 3′ RACE. The open reading frame of CasAQP-1 consists of 238 amino acids containing six helical structures and two NPA motifs for the water pore. The expression pattern of CasAQP-1 was ubiquitous in cDNAs from all tissues examined, although higher in the hepatopancreas, thoracic ganglia, abdominal muscle, and hypodermis and lower in the antennal gland, heart, hemocytes, ovary, eyestalk, brain, hindgut, Y-organs, and gill. Callinectes larvae differed in their capacity to molt in hyposalinity, as those at earlier stages from Zoea (Z) 1 to Z4 had lower molting rates than those from Z5 onwards, as compared to controls kept in 30 ppt water. No difference was found in the survival of larvae held at 15 and 30 ppt. CasAQP-1 expression differed with ontogeny during larval development, with significantly higher expression at Z1-2, compared to other larval stages. The exposure to 15 ppt affected larval-stage dependent CasAQP-1 expression which was significantly higher in Z2- 6 stages than the other larval stages. Conclusions We report the ontogenetic variation in CasAQP-1

  9. Toxicity of endosulfan on embryo-larval development of the South American toad Rhinella arenarum.

    PubMed

    Svartz, Gabriela V; Wolkowicz, Ianina R Hutler; Coll, Cristina S Pérez

    2014-04-01

    Endosulfan is a widely used pesticide despite its extreme toxicity to a variety of taxa and its worldwide ban. The aim of the present study was to evaluate the acute and chronic toxicity of endosulfan on the embryonic-larval development of the common South American toad Rhinella arenarum. The results showed that lethal and sublethal effects increased with concentration and exposure time. The sensitivity to endosulfan increased during the larval period, the complete operculum stage (S.25) being the most sensitive (504-h median lethal concentration [LC50] = 0.01 mg endosulfan/L; 10% lethal concentration [LC10] = 0.004 mg endosulfan/L). Endosulfan exposure caused morphological abnormalities such as general underdevelopment, edema, gill malformations, and cellular dissociation as well as neurotoxicity. Our results also showed that larvae exposed to concentrations of 0.005 mg endosulfan/L and 0.01 mg endosulfan/L completed metamorphosis earlier than controls, but with underdevelopment. The 240-h teratogenic index was 6.13, implying a high risk for embryos to be malformed in the absence of significant embryonic lethality. Because the hazard quotients for chronic exposure were over 1, the level of concern value and toxicity endpoints obtained in the present study for R. arenarum occurred at concentrations lower than the levels of endosulfan reported in the environment, this pesticide should be considered a potential risk for this species. PMID:24375551

  10. Particle motion is broadly represented in the vestibular medulla of the bullfrog across larval development.

    PubMed

    Simmons, Andrea Megela; Flores, Victoria

    2012-04-01

    In their shallow-water habitats, bullfrog (Rana catesbeiana) tadpoles are exposed to both underwater and airborne sources of acoustic stimulation. We probed the representation of underwater particle motion throughout the tadpole's dorsal medulla to determine its spatial extent over larval life. Using neurobiotin-filled micropipettes, we recorded neural activity to z-axis particle motion (frequencies of 40-200 Hz) in the medial vestibular nucleus, lateral vestibular nucleus, dorsal medullary nucleus (DMN), and along the dorsal arcuate pathway. Sensitivity was comparable in the medial and lateral vestibular nuclei, with estimated thresholds between 0.016 and 12.5 μm displacement. Neither best responding frequency nor estimated threshold varied significantly over larval stage. Transport of neurobiotin from active recording sites was also stable over development. The DMN responded poorly to z-axis particle motion, but did respond to low-frequency pressure stimulation. These data suggest that particle motion is represented widely and stably in the tadpole's vestibular medulla. This is in marked contrast to the representation of pressure stimulation in the auditory midbrain, where a transient "deaf period" of non-responsiveness and decreased connectivity occurs immediately prior to metamorphic climax. We suggest that, in bullfrogs, sensitivity to particle motion and to pressure follows different developmental trajectories. PMID:22198742

  11. lin-35/Rb cooperates with the SWI/SNF complex to control Caenorhabditis elegans larval development.

    PubMed Central

    Cui, Mingxue; Fay, David S; Han, Min

    2004-01-01

    Null mutations in lin-35, the Caenorhabditis elegans ortholog of the mammalian Rb protein, cause no obvious morphological defects. Using a genetic approach to identify genes that may function redundantly with lin-35, we have isolated a mutation in the C. elegans psa-1 gene. lin-35; psa-1 double mutants display severe developmental defects leading to early larval arrest and adult sterility. The psa-1 gene has previously been shown to encode a C. elegans homolog of yeast SWI3, a critical component of the SWI/SNF complex, and has been shown to regulate asymmetric cell divisions during C. elegans development. We observed strong genetic interactions between psa-1 and lin-35 as well as a subset of the class B synMuv genes that include lin-37 and lin-9. Loss-of-function mutations in lin-35, lin-37, and lin-9 strongly enhanced the defects of asymmetric T cell division associated with a psa-1 mutation. Our results suggest that LIN-35/Rb and a certain class B synMuv proteins collaborate with the SWI/SNF protein complex to regulate the T cell division as well as other events essential for larval growth. PMID:15280233

  12. Effects of temperature on embryonic and early larval growth and development in the rough-skinned newt (Taricha granulosa).

    PubMed

    Smith, Geoffrey D; Hopkins, Gareth R; Mohammadi, Shabnam; M Skinner, Heather; Hansen, Tyler; Brodie, Edmund D; French, Susannah S

    2015-07-01

    We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the rough-skinned newt (Taricha granulosa). We assigned newt eggs to different temperatures (7, 14, or 21°C); after hatching, we re-assigned the newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development. PMID:25965021

  13. Changes in digestive enzyme activities during larval development of leopard grouper (Mycteroperca rosacea).

    PubMed

    Martínez-Lagos, R; Tovar-Ramírez, D; Gracia-López, V; Lazo, J P

    2014-06-01

    The leopard grouper is an endemic species of the Mexican Pacific with an important commercial fishery and good aquaculture potential. In order to assess the digestive capacity of this species during the larval period and aid in the formulation of adequate weaning diets, this study aimed to characterize the ontogeny of digestive enzymes during development of the digestive system. Digestive enzymes trypsin, chymotrypsin, acid protease, leucine-alanine peptidase, alkaline phosphatase, aminopeptidase N, lipase, amylase and maltase were quantified in larvae fed live prey and weaned onto a formulated microdiet at 31 days after hatching (DAH) and compared with fasting larvae. Enzyme activity for trypsin, lipase and amylase were detected before the opening of the mouth and the onset of exogenous feeding, indicating a precocious development of the digestive system that has been described in many fish species. The intracellular enzyme activity of leucine-alanine peptidase was high during the first days of development, with a tendency to decrease as larvae developed, reaching undetectable levels at the end of the experimental period. In contrast, activities of enzymes located in the intestinal brush border (i.e., aminopeptidase and alkaline phosphatase) were low at the start of exogenous feeding but progressively increased with larval development, indicating the gradual maturation of the digestive system. Based on our results, we conclude that leopard grouper larvae possess a functional digestive system at hatching and before the onset of exogenous feeding. The significant increase in the activity of trypsin, lipase, amylase and acid protease between 30 and 40 DAH suggests that larvae of this species can be successfully weaned onto microdiets during this period. PMID:24189829

  14. Anatomy and development of the larval nervous system in Echinococcus multilocularis

    PubMed Central

    2013-01-01

    Background The metacestode larva of Echinococcus multilocularis (Cestoda: Taeniidae) develops in the liver of intermediate hosts (typically rodents, or accidentally in humans) as a labyrinth of interconnected cysts that infiltrate the host tissue, causing the disease alveolar echinococcosis. Within the cysts, protoscoleces (the infective stage for the definitive canid host) arise by asexual multiplication. These consist of a scolex similar to that of the adult, invaginated within a small posterior body. Despite the importance of alveolar echinococcosis for human health, relatively little is known about the basic biology, anatomy and development of E. multilocularis larvae, particularly with regard to their nervous system. Results We describe the existence of a subtegumental nerve net in the metacestode cysts, which is immunoreactive for acetylated tubulin-α and contains small populations of nerve cells that are labeled by antibodies raised against several invertebrate neuropeptides. However, no evidence was found for the existence of cholinergic or serotoninergic elements in the cyst wall. Muscle fibers occur without any specific arrangement in the subtegumental layer, and accumulate during the invaginations of the cyst wall that form brood capsules, where protoscoleces develop. The nervous system of the protoscolex develops independently of that of the metacestode cyst, with an antero-posterior developmental gradient. The combination of antibodies against several nervous system markers resulted in a detailed description of the protoscolex nervous system, which is remarkably complex and already similar to that of the adult worm. Conclusions We provide evidence for the first time of the existence of a nervous system in the metacestode cyst wall, which is remarkable given the lack of motility of this larval stage, and the lack of serotoninergic and cholinergic elements. We propose that it could function as a neuroendocrine system, derived from the nervous system

  15. Effect of larval food amount on ovariole development in queens of Trigona spinipes (Hymenoptera, Apinae).

    PubMed

    Lisboa, L C O; Serrão, J E; Cruz-Landim, C; Campos, L A O

    2005-06-01

    Caste determination in Trigona spinipes Fabricius (Hymenoptera, Apidae, Meliponini) is trophogenic. Larvae that eat about 360 microl of food become queens, while those who consume 36 microl develop into workers. We studied the effect of larval nutrition on the number and length of ovarioles and on ovarian development in fifth instar larvae, white eyed, pink eyed and black-eyed pupae as well as newly emerged adults. All larvae have four ovarioles per ovary, while in queen pupae this number ranged from 8 to 15. Cyst formation, the cell death and other characteristics of ovary morphogenesis were the same regardless of the quantity of food consumed. These results are discussed in relation to caste differentiation in other bees. PMID:15929734

  16. Otolith Growth and macular Carbonic Anhydrase Reactivity in larval Fish after Development at simulated Microgravity

    NASA Astrophysics Data System (ADS)

    Baur, U.; Hilbig, R.; Anken, R.

    Otolith growth in terms of mineralisation mainly depends on the enzyme carbonic anhydrase (CA). CA is located in specialized, mitochondria-rich macular cells (ionocytes), which are involved in the endolymphatic ion exchange, and the enzyme is responsible for the provision of the pH-value necessary for otolithic calcium carbonate deposition. Since it has been shown earlier that hypergravity slows down inner ear otolith growth in developing fish via a down-regulation of CA reactivity, we were prompted to elucidate whether (simulated) microgravity would possibly yield opposite effects. Therefore, larval siblings of cichlid fish (Oreochromis mossambicus) were housed in a submersed, two-dimensional clinostat (tube) during their development. Subsequently, the "physical capacity" (i.e., size) of the otoliths was measured, CA was histochemically demonstrated in ionocytes, and enzyme reactivity was determined densitometrically. The respective data will be communicated at the meeting. Acknowledgement: This work was financially supported by the German Aerospace Center (DLR) (FKZ: 50 WB 9997).

  17. The behavior of larval zebrafish reveals stressor-mediated anorexia during early vertebrate development

    PubMed Central

    De Marco, Rodrigo J.; Groneberg, Antonia H.; Yeh, Chen-Min; Treviño, Mario; Ryu, Soojin

    2014-01-01

    The relationship between stress and food consumption has been well documented in adults but less so in developing vertebrates. Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish. Furthermore, we provide indication that food intake suppression cannot be accounted for by changes in locomotion, oxygen consumption and visual responses, as they remain unaffected after exposure to a potent stressor. We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established. The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging. PMID:25368561

  18. The behavior of larval zebrafish reveals stressor-mediated anorexia during early vertebrate development.

    PubMed

    De Marco, Rodrigo J; Groneberg, Antonia H; Yeh, Chen-Min; Treviño, Mario; Ryu, Soojin

    2014-01-01

    The relationship between stress and food consumption has been well documented in adults but less so in developing vertebrates. Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish. Furthermore, we provide indication that food intake suppression cannot be accounted for by changes in locomotion, oxygen consumption and visual responses, as they remain unaffected after exposure to a potent stressor. We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established. The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging. PMID:25368561

  19. Embryonic, Larval, and Early Juvenile Development of the Tropical Sea Urchin, Salmacis sphaeroides (Echinodermata: Echinoidea)

    PubMed Central

    Rahman, M. Aminur; Yusoff, Fatimah Md.; Arshad, A.; Shamsudin, Mariana Nor; Amin, S. M. N.

    2012-01-01

    Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10−5 dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition. PMID:23055824

  20. Embryonic, larval, and early juvenile development of the tropical sea urchin, Salmacis sphaeroides (Echinodermata: Echinoidea).

    PubMed

    Rahman, M Aminur; Yusoff, Fatimah Md; Arshad, A; Shamsudin, Mariana Nor; Amin, S M N

    2012-01-01

    Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10(-5) dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition. PMID:23055824

  1. Proteomic Analysis of Oesophagostomum dentatum (Nematoda) during Larval Transition, and the Effects of Hydrolase Inhibitors on Development

    PubMed Central

    Ondrovics, Martina; Silbermayr, Katja; Mitreva, Makedonka; Young, Neil D.; Razzazi-Fazeli, Ebrahim; Gasser, Robin B.; Joachim, Anja

    2013-01-01

    In this study, in vitro drug testing was combined with proteomic and bioinformatic analyses to identify and characterize proteins involved in larval development of Oesophagostomum dentatum, an economically important parasitic nematode. Four hydrolase inhibitors ο-phenanthroline, sodium fluoride, iodoacetamide and 1,2-epoxy-3-(pnitrophenoxy)-propane (EPNP) significantly inhibited (≥90%) larval development. Comparison of the proteomic profiles of the development-inhibited larvae with those of uninhibited control larvae using two-dimensional gel electrophoresis, and subsequent MALDI-TOF mass spectrometric analysis identified a down-regulation of 12 proteins inferred to be involved in various larval developmental processes, including post-embryonic development and growth. Furthermore, three proteins (i.e. intermediate filament protein B, tropomyosin and peptidyl-prolyl cis-trans isomerase) inferred to be involved in the moulting process were down-regulated in moulting- and development-inhibited O. dentatum larvae. This first proteomic map of O. dentatum larvae provides insights in the protein profile of larval development in this parasitic nematode, and significantly improves our understanding of the fundamental biology of its development. The results and the approach used might assist in developing new interventions against parasitic nematodes by blocking or disrupting their key biological pathways. PMID:23717515

  2. Evaluation of growth and development of hatchery-reared larval black sea bass centropristis striata via image analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve the understanding of larval development and to refine hatchery production techniques for black sea bass Centropristis striata, digital photography and image analysis were employed to characterize growth and development of larvae from hatch through metamorphosis. Within 12 h after hatchin...

  3. Ocean warming ameliorates the negative effects of ocean acidification on Paracentrotus lividus larval development and settlement.

    PubMed

    García, Eliseba; Clemente, Sabrina; Hernández, José Carlos

    2015-09-01

    Ocean warming and acidification both impact marine ecosystems. All organisms have a limited body temperature range, outside of which they become functionally constrained. Beyond the absolute extremes of this range, they cannot survive. It is hypothesized that some stressors can present effects that interact with other environmental variables, such as ocean acidification (OA) that have the potential to narrow the thermal range where marine species are functional. An organism's response to ocean acidification can therefore be highly dependent on thermal conditions. This study evaluated the combined effects of predicted ocean warming conditions and acidification, on survival, development, and settlement, of the sea urchin Paracentrotus lividus. Nine combined treatments of temperature (19.0, 20.5 and 22.5 °C) and pH (8.1, 7.7 and 7.4 units) were carried out. All of the conditions tested were either within the current natural ranges of seawater pH and temperature or are within the ranges that have been predicted for the end of the century, in the sampling region (Canary Islands). Our results indicated that the negative effects of low pH on P. lividus larval development and settlement will be mitigated by a rise in seawater temperature, up to a thermotolerance threshold. Larval development and settlement performance of the sea urchin P. lividus was enhanced by a slight increase in temperature, even under lowered pH conditions. However, the species did show negative responses to the levels of ocean warming and acidification that have been predicted for the turn of the century. PMID:26275754

  4. Combined endosulfan and cypermethrin-induced toxicity to embryo-larval development of Rhinella arenarum.

    PubMed

    Svartz, Gabriela V; Aronzon, Carolina M; Pérez Coll, Cristina S

    2016-01-01

    The combined effects of two widely used pesticides, endosulfan and cypermethrin, on survival of embryo-larval development of the South American toad (Rhinella arenarum) were examined. The toxicity bioassays were performed according to the AMPHITOX test. Embryos and larvae were exposed to mixtures of these pesticides at equitoxic ratios from acute or chronic exposure to evaluate interaction effects. The results were analyzed using both Marking's additive index and combination index (CI)-isobologram methods. Acute (96-h) and intermediate (168-h) toxicity of endosulfan-cypermethrin mixtures remained almost constant for larvae and embryos, but when exposure duration was increased, there was a significant elevation in toxicity, obtaining chronic (240-h) no-observed-effect concentrations (NOEC) values of 0.045 and 0.16 mg/L for embryos and larvae, respectively. These are environmentally relevant concentrations that reflect a realistic risk of this pesticide mixture to this native amphibian species. The toxicity increment with the exposure duration was coincident with the central nervous system development on embryos reaching the larval period, the main target organ of these pesticides. The interactions of the pesticide mixtures at acute and chronic exposure were antagonistic for embryo development (CI > 1), and additive (CI = 1) for larvae, while chronic exposure interactions were synergistic (CI < 1) for both developmental periods. Data indicated that endosulfan-cypermethrin mixtures resulted in different interaction types depending on duration and developmental stage exposed. As a general pattern and considering conditions of overall developmental period and chronic exposure, this pesticide mixture usually applied in Argentine crop fields is synergistic with respect to toxicity for this native amphibian species. PMID:26914601

  5. [Embrionary and larval development of Lytechinus variegatus (Echinoidea: Toxopneustidae) in laboratory conditions at Isla de Margarita-Venezuela].

    PubMed

    Gómez, Olga; Gómez, Alfredo

    2005-12-01

    The sea urchin Lytechinus variegatus is a promissory species for aquaculture activities in tropical countries. In Venezuela, this species has some economical importance but their embryonic and larval development had not been studied. We collected specimens from seagrass beds in Margarita Island (Venezuela) and kept them in the laboratory, where they spawned naturally. With filtered sea water (temperature 28 degrees C, salinity 37 psu) and moderate aeration, the eggs and sperm were mixed (relation 1:100) and reached a 90% fertilization rate. The fertilization envelope was observed after two minutes, the first cellular division after 45 minutes and the prism larval stage after 13 hours. The echinopluteus larval stage was reached after 17 hours and metamorphosis after 18 days of planktonic life, when the larvae start their benthic phase. PMID:17469261

  6. Temperature, Larval Diet, and Density Effects on Development Rate and Survival of Aedes aegypti (Diptera: Culicidae)

    PubMed Central

    Couret, Jannelle; Dotson, Ellen; Benedict, Mark Q.

    2014-01-01

    Many environmental factors, biotic and abiotic interact to influence organismal development. Given the importance of Aedes aegypti as a vector of human pathogens including dengue and yellow fever, understanding the impact of environmental factors such as temperature, resource availability, and intraspecific competition during development is critical for population control purposes. Despite known associations between developmental traits and factors of diet and density, temperature has been considered the primary driver of development rate and survival. To determine the relative importance of these critical factors, wide gradients of conditions must be considered. We hypothesize that 1) diet and density, as well as temperature influence the variation in development rate and survival, 2) that these factors interact, and this interaction is also necessary to understand variation in developmental traits. Temperature, diet, density, and their two-way interactions are significant factors in explaining development rate variation of the larval stages of Ae. aegypti mosquitoes. These factors as well as two and three-way interactions are significantly associated with the development rate from hatch to emergence. Temperature, but not diet or density, significantly impacted juvenile mortality. Development time was heteroskedastic with the highest variation occurring at the extremes of diet and density conditions. All three factors significantly impacted survival curves of experimental larvae that died during development. Complex interactions may contribute to variation in development rate. To better predict variation in development rate and survival in Ae. aegypti, factors of resource availability and intraspecific density must be considered in addition, but never to the exclusion of temperature. PMID:24498328

  7. The formation of the nervous system during larval development in Triops cancriformis (Bosc) (crustacea, Branchiopoda): An immunohistochemical survey.

    PubMed

    Fritsch, Martin; Richter, Stefan

    2010-12-01

    We provide data of the development of thenervous system during the first five larval stages of Triops cancriformis. We use immunohistochemical labeling (against acetylated α-tubulin, serotonin, histamine, and FMRFamide), confocal laser scanning microscopy analysis, and 3D-reconstruction. The development of the nervous system corresponds with the general anamorphic development in T. cancriformis. In larval stage I (L I), all brain parts (proto-, deuto-, and tritocerebrum), the circumoral connectives, and the mandibular neuromere are already present. Also, the frontal filaments and the developing nauplius eye are already present. However, until stage L III, the nauplius eye only consists of three cups. Throughout larval development, the protocerebral network differentiates into distinct subdivisions. In the postnaupliar region, additional neuromeres and their commissures emerge in an anteroposterior gradient. The larval nervous system in L V consists of a differentiated protocerebrum including a central body, a nauplius eye comprising four cups, a circumoral nerve ring, mandibular- and postnaupliar neuromeres up to the seventh thoracic segment, each featuring an anterior and a posterior commissure, and two parallel connectives. The presence of a protocerebral bridge is questionable. The distribution of neurotransmitters in L I is restricted to the naupliar nervous system. Over the course of the five stages of development, neurotransmitter distribution also follows an anteroposterior gradient. Each neuromere is equipped with two ganglia innervating the locomotional appendages and possesses a specific neurotransmitter distribution pattern. We suggest a correlation between neurotransmitter expression and locomotion. PMID:20938985

  8. Exploration of the “larval pool”: development and ground-truthing of a larval transport model off leeward Hawai‘i

    PubMed Central

    Kobayashi, Donald R.

    2016-01-01

    Most adult reef fish show site fidelity thus dispersal is limited to the mobile larval stage of the fish, and effective management of such species requires an understanding of the patterns of larval dispersal. In this study, we assess larval reef fish distributions in the waters west of the Big Island of Hawai‘i using both in situ and model data. Catches from Cobb midwater trawls off west Hawai‘i show that reef fish larvae are most numerous in offshore waters deeper than 3,000 m and consist largely of pre-settlement Pomacanthids, Acanthurids and Chaetodontids. Utilizing a Lagrangian larval dispersal model, we were able to replicate the observed shore fish distributions from the trawl data and we identified the 100 m depth strata as the most likely depth of occupancy. Additionally, our model showed that for larval shore fish with a pelagic larval duration longer than 40 days there was no significant change in settlement success in our model. By creating a general additive model (GAM) incorporating lunar phase and angle we were able to explain 67.5% of the variance between modeled and in situ Acanthurid abundances. We took steps towards creating a predictive larval distribution model that will greatly aid in understanding the spatiotemporal nature of the larval pool in west Hawai‘i, and the dispersal of larvae throughout the Hawaiian archipelago. PMID:26855873

  9. Fine-scale temperature fluctuation and modulation of Dirofilaria immitis larval development in Aedes aegypti.

    PubMed

    Ledesma, Nicholas; Harrington, Laura

    2015-04-15

    We evaluated degree-day predictions of Dirofilaria immitis development (HDU) under constant and fluctuating temperature treatments of equal average daily temperature. Aedes aegypti mosquitoes were infected with D. immitis microfilariae and parasite development was recorded at set time points in dissected mosquitoes. Time to L3 development in Malpighian tubules and detection in mosquito heads was shorter for larvae experiencing a daily regime of 19±9°C than larvae at constant 19°C; larval development rate in Malpighian tubules was slower in fluctuating regimes maintained above the 14°C developmental threshold than larvae under constant temperatures. We showed that hourly temperature modeling more accurately predicted D. immitis development to infective L3 stage. Development time differed between fluctuating and constant temperature treatments spanning the 14°C development threshold, implicating a physiological basis for these discrepancies. We conclude that average daily temperature models underestimate L3 development-and consequently dog heartworm transmission risk-at colder temperatures, and spatiotemporal models of D. immitis transmission risk should use hourly temperature data when analyzing high daily temperature ranges spanning 14°C. PMID:25747489

  10. GROWTH AND CHANGES IN BIOCHEMICAL COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986

    EPA Science Inventory

    Larval development in Menippe adina was associated with changes in weight and biochemical composition. Larvae of the stone crab, M. adina, were mass-reared under laboratory conditions (28|C; 20o/ooS) from hatching to the megalopal stage. Growth in M. adina is exponential througho...

  11. Oviposition and larval development of a stem borer, Eoreuma loftini, on rice and non-crop grass hosts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A greenhouse study compared oviposition preference and larval development duration of a stem borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), on rice, Oryza sativa L. (cv. Cocodrie), and four primary non-crop hosts of Gulf Coast Texas rice agroecosystems. Rice and two perennials, johnsongrass...

  12. Embryonic and larval development in the caecilian Ichthyophis kohtaoensis (Amphibia, gymnophiona): a staging table.

    PubMed

    Dünker, N; Wake, M H; Olson, W M

    2000-01-01

    Little is known about the developmental biology of caecilians-tropical, elongate, limbless, mostly fossorial amphibians that are members of the Order Gymnophiona. Ichthyophis kohtaoensis (Family Ichthyophiidae; southeast Asia) is an oviparous species in which maternal care of the clutch is provided. The clutch is laid in a burrow on land, and the embryos develop in their egg membranes, curved around a large yolk mass. Larvae are aquatic and exhibit characteristic features that are not present in the terrestrial adults. Because accurate descriptions of ontogenies and the establishment of standardized stages of embryonic and larval development are useful for both experimental and comparative embryology, a staging table for I.kohtaoensis was developed based on external morphological features. Development from the end of neurulation to metamorphosis was divided into 20 stages. Principal diagnostic features include development of the lateral line organs, formation of three pairs of external gills, development of the eyes, changes in yolk structure, changes in the structure of the cloacal aperture and growth of the tail, including the formation and regression of the tail fin. This study provides a comparison with descriptions of embryonic stages of I.glutinosus and Hypogeophis rostratus and with a recent staging table for the aquatic, viviparous caecilian Typhlonectes compressicauda, the only other caecilians for which reasonably complete ontogenetic information exists in the literature. Comparisons with established staging tables for selected frogs and salamanders are also presented. PMID:10629095

  13. Effects of temperature and salinity on larval development of Elminius modestus (Crustacea, Cirripedia) from Helgoland (North Sea) and New Zealand

    NASA Astrophysics Data System (ADS)

    Harms, J.

    1986-12-01

    Larvae of Elminius modestus (Darwin) from four different populations (Portobello, Leigh, Doubtless Bay [New Zealand] and Helgoland [North Sea]) were reared at different salinity and temperature combinations. The larvae of E. modestus from Helgoland developed successfully at a wide range of temperature (6° to 24 °C) and salinity (20 to 50 ‰ S). Mortality was highest at 10 ‰ S; only at 12° and 18 °C did a small percentage develop to the cypris. The larvae from New Zealand were reared at a temperature range of 12° 24 °C at 20, 30 and 40 ‰ S; mortality increased in all populations at all salinities with decreasing temperature and was extremely high at 12 °C and 40 ‰ S. The temperature influence on larval duration could be described in all cases by a power function. No significant differences in temperature influences on developmental times between the tested salinities were found, except for the Portobello population at 20 ‰ S. Significant differences were found in the temperature influence on larval development between the populations from Helgoland and the North Island of New Zealand (Leigh, Doubtless Bay). No differences were found between the Helgoland and Portobello population. The pooled data for the temperature influence on the larval development of the three tested New Zealand populations at 20, 30 and 40 ‰ S and the pooled Helgoland data at 20, 30 and 40 ‰ S show highly significant differences. Larval size (stage VI) was influenced by experimental conditions. The larvae grew bigger at low temperatures and attained their maximum size at 30 ‰ S (Helgoland). There was a strong reduction in larval size at temperatures from 18° to 24 °C. The larvae of the New Zealand populations were smaller than those from Helgoland. The greatest difference in size existed between the larvae from Portobello and Helgoland.

  14. Persistent Activation of the Innate Immune Response in Adult Drosophila Following Radiation Exposure During Larval Development

    PubMed Central

    Sudmeier, Lisa J.; Samudrala, Sai-Suma; Howard, Steven P.; Ganetzky, Barry

    2015-01-01

    Cranial radiation therapy (CRT) is an effective treatment for pediatric central nervous system malignancies, but survivors often suffer from neurological and neurocognitive side effects that occur many years after radiation exposure. Although the biological mechanisms underlying these deleterious side effects are incompletely understood, radiation exposure triggers an acute inflammatory response that may evolve into chronic inflammation, offering one avenue of investigation. Recently, we developed a Drosophila model of the neurotoxic side effects of radiation exposure. Here we use this model to investigate the role of the innate immune system in response to radiation exposure. We show that the innate immune response and NF-ĸB target gene expression is activated in the adult Drosophila brain following radiation exposure during larval development, and that this response is sustained in adult flies weeks after radiation exposure. We also present preliminary data suggesting that innate immunity is radioprotective during Drosophila development. Together our data suggest that activation of the innate immune response may be beneficial initially for survival following radiation exposure but result in long-term deleterious consequences, with chronic inflammation leading to impaired neuronal function and viability at later stages. This work lays the foundation for future studies of how the innate immune response is triggered by radiation exposure and its role in mediating the biological responses to radiation. These studies may facilitate the development of strategies to reduce the deleterious side effects of CRT. PMID:26333838

  15. Evolution and plasticity of anuran larval development in response to desiccation. A comparative analysis.

    PubMed

    Richter-Boix, Alex; Tejedo, Miguel; Rezende, Enrico L

    2011-09-01

    Anurans breed in a variety of aquatic habitats with contrasting levels of desiccation risk, which may result in selection for faster development during larval stages. Previous studies suggest that species in ephemeral ponds reduce their developmental times to minimize desiccation risks, although it is not clear how variation in desiccation risk affects developmental strategies in different species. Employing a comparative phylogenetic approach including data from published and unpublished studies encompassing 62 observations across 30 species, we tested if species breeding in ephemeral ponds (High risk) develop faster than those from permanent ponds (Low risk) and/or show increased developmental plasticity in response to drying conditions. Our analyses support shorter developmental times in High risk, primarily by decreasing body mass at metamorphosis. Plasticity in developmental times was small and did not differ between groups. However, accelerated development in High risk species generally resulted in reduced sizes at metamorphosis, while some Low risk species were able compensate this effect by increasing mean growth rates. Taken together, our results suggest that plastic responses in species breeding in ephemeral ponds are constrained by a general trade-off between development and growth rates. PMID:22393479

  16. Developing a Novel Embryo-Larval Zebrafish Xenograft Assay to Prioritize Human Glioblastoma Therapeutics.

    PubMed

    Wehmas, Leah Christine; Tanguay, Robert L; Punnoose, Alex; Greenwood, Juliet A

    2016-08-01

    Glioblastoma is an aggressive brain cancer requiring improved treatments. Existing methods of drug discovery and development require years before new therapeutics become available to patients. Zebrafish xenograft models hold promise for prioritizing drug development. We have developed an embryo-larval zebrafish xenograft assay in which cancer cells are implanted in a brain microenvironment to discover and prioritize compounds that impact glioblastoma proliferation, migration, and invasion. We illustrate the utility of our assay by evaluating the well-studied, phosphatidylinositide 3-kinase inhibitor LY294002 and zinc oxide nanoparticles (ZnO NPs), which demonstrate selective cancer cytotoxicity in cell culture, but the in vivo effectiveness has not been established. Exposures of 3.125-6.25 μM LY294002 significantly decreased proliferation up to 34% with concentration-dependent trends. Exposure to 6.25 μM LY294002 significantly inhibited migration/invasion by ∼27% within the glioblastoma cell mass (0-80 μm) and by ∼32% in the next distance region (81-160 μm). Unexpectedly, ZnO enhanced glioblastoma proliferation by ∼19% and migration/invasion by ∼35% at the periphery of the cell mass (161+ μm); however, dissolution of these NPs make it difficult to discern whether this was a nano or ionic effect. These results demonstrate that we have a short, relevant, and sensitive zebrafish-based assay to aid glioblastoma therapeutic development. PMID:27158859

  17. Evolution of poecilogony from planktotrophy: cryptic speciation, phylogeography, and larval development in the gastropod genus Alderia.

    PubMed

    Ellingson, Ryan A; Krug, Patrick J

    2006-11-01

    Poecilogony, a rare phenomenon in marine invertebrates, occurs when alternative larval morphs differing in dispersal potential or trophic mode are produced from a single genome. Because both poecilogony and cryptic species are prevalent among sea slugs in the suborder Sacoglossa (Gastropoda: Opisthobranchia), molecular data are needed to confirm cases of variable development and to place them in a phylogenetic context. The nominal species Alderia modesta produces long-lived, feeding larvae throughout the North Atlantic and Pacific, but in California can also produce short-lived larvae that metamorphose without feeding. We collected morphological, developmental, and molecular data for Alderia from 17 sites spanning the eastern and western Pacific and North Atlantic. Estuaries south of Bodega Harbor, California, contained a cryptic species (hereafter Alderia sp.) with variable development, sister to the strictly planktotrophic A. modesta. The smaller Alderia sp. seasonally toggled between planktotrophy and lecithotrophy, with some individuals differing in development but sharing mitochondrial DNA haplotypes. The sibling species overlapped in Tomales Bay, California, but showed no evidence of hybridization; laboratory mating trials suggest postzygotic isolation has arisen. Intra- and interspecific divergence times were estimated using a molecular clock calibrated with geminate sacoglossans. Speciation occurred about 4.1 million years ago during a major marine radiation in the eastern Pacific, when large inland embayments in California may have isolated ancestral populations. Atlantic and Pacific A. modesta diverged about 1.7 million years ago, suggesting trans-Arctic gene flow was interrupted by Pleistocene glaciation. Both Alderia species showed evidence of late Pleistocene population expansion, but the southern Alderia sp. likely experienced a more pronounced bottleneck. Reduced body size may have incurred selection against obligate planktotrophy in Alderia sp. by

  18. INFLUENCE OF AN INSECT GROWTH REGULATOR ON LARVAL DEVELOPMENT OF A MARINE CRUSTACEAN

    EPA Science Inventory

    Larval survival, growth, and energy metabolism of an estuarine shrimp (Palaemonetes pugio) were altered by exposure to low micrograms/l concentrations of an insect growth regulator (the juvenile hormone analogue, methoprene). Larvae were several orders of magnitude more sensitive...

  19. VARIATION IN GROWTH, LIPID CLASS AND FATTY ACID COMPOSITION OF THE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) DURING LARVAL DEVELOPMENT FOLLOWING EXPOSURE TO AN INSECT JUVENILE HORMONE ANALOG (FENOXYCARB)

    EPA Science Inventory

    This study examines the effects of fenoxycarb?, an insect juvenile hormone analog, on larval growth, and lipid class and fatty acid composition in first crabs of the mud crab Rhithropanopeus harrisii reared through total larval development in nominal water concentrations from 1 ...

  20. Larval serum proteins of the gypsy moth, Lymantria dispar: Allometric changes during development suggest several functions for arylphorin and lipophorin

    SciTech Connect

    Karpells, S.T.

    1989-01-01

    Storage proteins are the major nutritive intermediates in insects and although the serum storage proteins are relatively well studied, definitive roles for many of them have yet to be established. To further characterize their roles in development and to establish quantitative baselines for future studies, two serum proteins, arylphorin (Ap) and lipophorin (Lp), of the gypsy moth, Lymantria dispar, were studied. Ap and Lp, isolated from larval hemolymph, were partially characterized biochemically and immunologically. Hemolymph concentrations throughout larval development were determined using quantitative immunoelectrophoresis and absolute hemolymph amounts of protein were determined by measuring hemolymph volume. Cyclic fluctuations in hemolymph concentrations of Ap in particular correlated with each molting cycle and an increase in Lp levels just prior to pupation suggest a metamorphic change in the role or demand for the protein. Sexual dimorphism in protein concentrations are explained in part by the sexual dimorphism in the number of larval instars. In fact, an additional instar of Ap accumulation in the female gypsy moth is suggested to compensate for the lack of a female-specific storage protein in this species. The last two days of each instar were found to be the optimum time to sample protein concentration with minimum variance. Allometric relationships among Ap accumulation, Lp accumulation and weight gain were uncovered. Ap labelled with ({sup 14}C)-N-ethylmaleimide was shown to be incorporated into newly synthesized cuticle and setae during a larval-larval molt. The antiserum developed against L. dispar Ap was used to identify the Ap of Trichoplusia in and study Ap titers in parasitized T. in larvae. The antiserum was also used to determine the immunological relatedness of 5 species of Lepidoptera.

  1. Influence of starvation on the larval development of Hyas araneus (Decapoda, Majidae)

    NASA Astrophysics Data System (ADS)

    Anger, K.; Dawirs, R. R.

    1981-09-01

    The influence of starvation on larval development of the spider crab Hyas araneus (L.) was studied in laboratory experiments. No larval stage suffering from continual lack of food had sufficient energy reserves to reach the next instar. Maximal survival times were observed at four different constant temperatures (2°, 6°, 12° and 18 °C). In general, starvation resistance decreased as temperatures increased: from 72 to 12days in the zoea-1, from 48 to 18 days in the zoea-2, and from 48 to 15 days in the megalopa stage. The length of maximal survival is of the same order of magnitude as the duration of each instar at a given temperature. “Sublethal limits” of early starvation periods were investigated at 12 °C: Zoea larvae must feed right from the beginning of their stage (at high food concentration) and for more than one fifth, approximately, of that stage to have at least some chance of surviving to the next instar, independent of further prey availability. The minimum time in which enough reserves are accumulated for successfully completing the instar without food is called “point-of-reserve-saturation” (PRS). If only this minimum period of essential initial feeding precedes starvation, development in both zoeal stages is delayed and mortality is greater, when compared to the fed control. Starvation periods beginning right after hatching of the first zoea cause a prolongation of this instar and, surprisingly, a slight shortening of the second stage. The delay in the zoea-1 increases proportionally to the length of the initial fasting period. If more than approximately 70 % of the maximum possible survival time has elapsed without food supply, the larvae become unable to recover and to moult to the second stage even when re-fed (“point-of-no-return”, PNR). The conclusion, based on own observations and on literature data, is that initial feeding is of paramount importance in the early development of planktotrophic decapod larvae. Taking into account

  2. Larval growth, development, and survival of laboratory-reared Aplysia californica: Effects of diet and veliger density*

    PubMed Central

    Capo, Thomas R.; Bardales, Ana T.; Gillette, Phillip R.; Lara, Monica R.; Schmale, Michael C.; Serafy, Joseph E.

    2009-01-01

    Over the last three decades, the California sea hare, Aplysia californica, has played an increasingly important role as a model organism in the neurosciences. Since 1995, the National Resource for Aplysia has supported a growing research community by providing a consistent supply of laboratory-reared individuals of known age, reproductive status, and environmental history. The purpose of the present study was to resolve the key biological factors necessary for successful culture of large numbers of high quality larval Aplysia. Data from a sequence of five experiments demonstrated that algal diet, food concentration, and veliger density significantly affected growth, attainment of metamorphic competency, and survival of Aplysia larvae. The highest growth and survival were achieved with a mixed algal diet of 1:1 Isochrysis sp (TISO) and Chaetoceros muelleri (CHGRA) at a total concentration of 250 x 103 cells/mL and a larval density of 0.5 – 1.0 per mL. Rapid growth was always correlated with faster attainment of developmental milestones and increased survival, indicating that the more rapidly growing larvae were healthier. Trials conducted with our improved protocol resulted in larval growth rates of >14 μm/d, which yielded metamorphically competent animals within 21 days with survival rates in excess of 90%. These data indicate the important effects of biotic factors on the critical larval growth period in the laboratory and show the advantages of developing optimized protocols for culture of such marine invertebrates. PMID:19000779

  3. Embryonic and larval development in barfin flounder Verasper moseri (Jordan and Gilbert)

    NASA Astrophysics Data System (ADS)

    Du, Rongbin; Wang, Yongqiang; Jiang, Haibin; Liu, Liming; Wang, Maojian; Li, Tianbao; Zhang, Shubao

    2010-01-01

    Broodstock of Verasper moseri (Jordan and Gilbert) aged 3-4 years old were selected, and reinforced cultivation was conducted to promote maturation under controlled water temperature and photoperiod conditions. Fertilized eggs were obtained by artificial fertilization, and the development of embryos, larvae and juveniles was observed continuously. The results showed that the fertilized eggs of V. moseri were spherical, with transparent yolk and homogeneous bioplasm, and had no oil globule inside. The average diameter of the eggs was 1.77±0.02 mm. The eggs of V. moseri were buoyant in water with salinity above 35. The cleavage type was typical discoidal. Young pigment cells appeared when olfactory plates began to form. Hatching occurred at 187 h after fertilization at a water temperature of 8.5°C. The newly hatched larvae, floating on the water surface, were transparent with an average total length of 4.69±0.15 mm. During the cultivation period, when the water temperature was raised from 9 to 14.5°C, 4-day old larvae showed more melanophores on the body surface, making the larvae gray in color. The pectoral fins began to develop, which enabled the larvae to swim horizontally and in a lively manner. On days 7-8, the digestive duct formed. The yolk sac was small and black. The yolk sac was absorbed on day 11. Larvae took food actively, and body length and body height clearly increased. The rudiments of dorsal and anal fin pterygiophores were discernible and caudal fin ray elements formed on day 19. On day 24, the larval notochord flexed upwards, and the rays of unpaired fins began to differentiate. Pigment cells converged on the dorsal and anal fin rays, and the mastoid teeth on the mandible appeared. On day 29, the left eyes of juveniles began to move upwards. Depigmentation began in some juveniles and they became sandy brown in color on day 37. Most juveniles began to settle on the bottom of the tank. The left eyes of juveniles migrated completely to the right

  4. Laboratory observation on spawning, fecundity and larval development of amphioxus ( Branchiostoma belcheri Tsingtaunese)

    NASA Astrophysics Data System (ADS)

    Wu, Xian-Han; Zhang, Shi-Cui; Wang, Yong-Yuan; Zhang, Bao-Lu; Qu, Yan-Mei; Jiang, Xin-Ji

    1994-12-01

    Although amphioxus is widespread in temperate and tropical seas, its population is diminishing because of environmental pollution. To keep the population of this evolutionarily important animal from diminishing, study on its reproduction and development is necessary. The main findings in this study on the spawning and fecundity of the amphioxus reared in laboratory and its larval development are as follows. 1. Water temperature markedly affected the spawning. It spawned only when water temperature reached 21°C. 2. Spawning of the amphioxus in laboratory was markedly extended. Initially, the amphioxus spawned at about 7:00 PM, but spawning time was postponed as spawning days went on. 3. The number of eggs produced by a female ranged from 1400 to 12800, average of 5800. This also represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time. 4. During the first few months of life of the amphioxus, its growth rate changed seasonally. The growth rate in summer and fall was greater than that in winter. 5. The pelagic larva became a benthic adult after 50 days. 6. The amphioxus reared in laboratory from fertilized eggs could produce fertile eggs and sperms. These findings can be a foundation for measures to address the problem of diminishing amphioxus population.

  5. Acidic intracellular pH shift during Caenorhabditis elegans larval development

    SciTech Connect

    Wadsworth, W.G.; Riddle, D.L. )

    1988-11-01

    During recovery from the developmentally arrested, nonfeeding dauer stage of the nemotode Caenorhabditis elegans, metabolic activation is accompanied by a decrease in intracellular pH (pH{sub i}). Phosphorus-31 nuclear magnetic resonance ({sup 31}P 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 pH{sub i} shift in other organisms, in vivo {sup 31}P NMR analysis of recovering dauer larvae shows a pH{sub i} decrease from {approx} 7.3 to {approx} 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 pH{sub i} may be important in the regulation of larval development in nematodes.

  6. The development of the digestive tract in larval European catfish (Silurus glanis L.).

    PubMed

    Kozarić, Z; Kuzir, S; Petrinec, Z; Gjurcević, E; Bozić, M

    2008-04-01

    The European catfish, Silurus glanis L., has become an important aqua cultural fish in Croatia, and it is cultivated extensively in ponds in polyculture with carps. The development of the digestive tract in S. glanis was studied with the aim of improving intensive fish production. Research was carried out on S. glanis larval stadium from 1- to 19-day post-hatching (DPH). The main histological methods used were: haematoxylin and eosin staining, periodic acid Schiff staining (PAS), Alcian blue (AB) and toluidin blue staining (TB). A yolk sac was present during the first 5 days (1-5-DPH). During the initial 3-DPH period, there was no trace PAS and AB activity in the digestive tract. Differentiation of the digestive tract began at 3- to 5-DPH. The oesophagus was positive for AB at 5-DPH, PAS and TB after 7-DPH. Differentiation of enterocytes began at 5-DPG and the intestines were complete at 11-DPH. Development of liver and pancreas was also studied. The analysis of data obtained in this study suggests that after 5-DPH catfish larvae have morphologically completed digestive tracts. PMID:18333856

  7. Early embryo and larval development of inviable intergeneric hybrids derived from Crassostrea angulata and Saccostrea cucullata

    NASA Astrophysics Data System (ADS)

    Su, Jiaqi; Wang, Zhaoping; Zhang, Yuehuan; Yan, Xiwu; Li, Qiongzhen; Yu, Ruihai

    2016-06-01

    To detect the intergeneric hybridization between the oyster Crassostrea angulata and Saccostrea cucullata coexisting along the southern coast of China, reciprocal crosses were conducted between the two species. Barriers for sperm recognizing, binding, penetrating the egg, and forming the pronucleus were detected by fluorescence staining. From the results, although fertilization success was observed in hybrid crosses, the overall fertilization rate was lower than that of intraspecific crosses. A large number of hybrid larvae died at 6-8 d after hatching, and those survived could not complete metamorphosis. C. angulata ♀× S. cucullata ♂ larvae had a growth rate similar to that of the maternal species, whereas S. cucullata ♀ × C. angulata ♂ larvae grew the slowest among all crosses. Molecular genetics analysis revealed that hybrid progeny were amphimixis hybrids. This study demonstrated that hybrid embryos generated by crossing C. angulata and S. cucullata could develop normally to the larval state, but could not complete metamorphosis and then develop to the spat stage. Thus, there is a post-reproductive isolation between C. angulata and S. cucullata.

  8. Development of the GABA-ergic signaling system and its role in larval swimming in sea urchin.

    PubMed

    Katow, Hideki; Abe, Kouki; Katow, Tomoko; Zamani, Alemeh; Abe, Hirokazu

    2013-05-01

    The present study aimed to elucidate the development and γ-amino butyric acid (GABA)-ergic regulation of larval swimming in the sea urchin Hemicentrotus pulcherrimus by cloning glutamate decarboxylase (Hp-gad), GABAA receptor (Hp-gabrA) and GABAA receptor-associated protein (Hp-gabarap), and by performing immunohistochemistry. The regulation of larval swimming was increasingly dependent on the GABAergic system, which was active from the 2 days post-fertilization (d.p.f.) pluteus stage onwards. GABA-immunoreactive cells were detected as a subpopulation of secondary mesenchyme cells during gastrulation and eventually constituted the ciliary band and a subpopulation of blastocoelar cells during the pluteus stage. Hp-gad transcription was detected by RT-PCR during the period when Hp-Gad-positive cells were seen as a subpopulation of blastocoelar cells and on the apical side of the ciliary band from the 2 d.p.f. pluteus stage. Consistent with these observations, inhibition of GAD with 3-mercaptopropioninc acid inhibited GABA immunoreactivity and larval swimming dose dependently. Hp-gabrA amplimers were detected weakly in unfertilized eggs and 4 d.p.f. plutei but strongly from fertilized eggs to 2 d.p.f. plutei, and Hp-GabrA, together with GABA, was localized at the ciliary band in association with dopamine receptor D1 from the two-arm pluteus stage. Hp-gabarap transcription and protein expression were detected from the swimming blastula stage. Inhibition of the GABAA receptor by bicuculline inhibited larval swimming dose dependently. Inhibition of larval swimming by either 3-mercaptopropionic acid or bicuculline was more severe in older larvae (17 and 34 d.p.f. plutei) than in younger ones (1 d.p.f. prism larvae). PMID:23307803

  9. Megalodicopia hians in the Monterey submarine canyon: Distribution, larval development, and culture

    NASA Astrophysics Data System (ADS)

    Havenhand, Jon. N.; Matsumoto, George I.; Seidel, Ed

    2006-02-01

    The exclusively deep-sea ascidian family Octacnemidae comprises several genera in which the oral siphon has hypertrophied to form two large lips which create an "oral hood" capable of capturing motile prey. Megalodicopia hians is typical of this carnivorous family and has been reported to prey upon small epibenthic crustaceans. Distribution of M. hians in the Monterey Canyon system (36°45'N, 122°00'W) (California) was determined with remotely operated vehicles. M. hians was found sparsely to depths of at least 3800 m throughout the canyon; however, abundance was greatest within the oxygen-minimum zone (400-800 m). Eggs, sperm, and recently fertilized embryos were obtained repeatedly from adults returned to the laboratory in vivo, indicating that this species free-spawns routinely. Overall egg diameter (ovum plus chorion, plus follicle cells) was 175-190 μm—considerably smaller than previously reported for this species. Embryonic development at temperature and oxygen concentrations equivalent to the oxygen-minimum zone was 2-4 d and, embryos gave rise to typical phlebobranch "simple" tadpole larvae. Larval period was extremely variable, and settlement/metamorphosis occurred up to 3 months post-hatching. These results are discussed within the context of settlement-site selection and fertilization ecology of the species.

  10. Larval development of Angiostrongylus vasorum in the land snail Helix aspersa.

    PubMed

    Di Cesare, Angela; Crisi, Paolo Emidio; Bartolini, Roberto; Iorio, Raffaella; Talone, Tonino; Filippi, Laura; Traversa, Donato

    2015-10-01

    The metastrongyloid nematode Angiostrongylus vasorum affects the heart and pulmonary arteries of dogs and wild animals. Over the recent years, dog angiostrongylosis has gained great attention in the veterinary community for the expansion of its geographic range and for a rise in the number of clinical cases. Global warming, changes in phenology of mollusc intermediate hosts and movements of wild reservoirs have been evocated in the spreading of mollusc-borne parasites, including A. vasorum. The land snail Helix aspersa, a vector of other respiratory metastrongyloids, is endemic in most regions of the World, where it is a pest outside its native Mediterranean range. In the present study, the susceptibility and suitability of H. aspersa as an intermediate host of A. vasorum were investigated along with the characteristics of larval recovery and development following two different ways of inoculation, i.e. experimental (group A) vs natural infection (group B). After infections, the snails were kept at environmental conditions for 2 months. Five snails from groups A and B were randomly selected, digested and examined at 15-day intervals for 2 months. L1s, L2s and L3s were microscopically identified based on key morphological and morphometric characteristics and their identity was genetically confirmed. The results showed that A. vasorum may reach the infective stage in H. aspersa and that uptake of larvae and parasitic burden within the snails depend on the grazing capability of the molluscs. Biological and epidemiological implications are discussed. PMID:26122991

  11. Inner Ear Otolith Growth in larval Fish after Development at simulated Microgravity

    NASA Astrophysics Data System (ADS)

    Baur, U.; Hilbig, R.; Anken, R.

    It has been shown earlier that hypergravity slows down inner ear otolith growth in developing fish via a down-regulation of carbonic anhydrase reactivity as an adaptation towards altered environmental gravity We were thus prompted to elucidate whether clinorotation would possibly yield opposite effects Therefore larval siblings of cichlid fish Oreochromis mossambicus were housed in a submersed two-dimensional clinostat Two tubes with different diameters were used 10 5 mm large tube LT and 3 5 mm small tube ST experimental time-span 10 and 7 days respectively After the experiments otoliths were dissected and their size area grown during the experiments was determined planimetrically In case of the LT-clinorotated fish both utricular and saccular otoliths lapilli and sagittae respectively were significantly smaller than those of the 1g-controls In contrast ST-maintenance resulted in significantly larger otoliths lapilli only no statistical significant difference regarding sagittae observed The results from LT-clinorotation therefore indicate that the animals had in fact received hypergravity whereas the ST-data are to be interpreted as being effected by simulated microgravity conditions In conclusion otolith growth is affected by the gravitational vector in a dose-dependent manner Acknowledgement This work was financially supported by the German Aerospace Center DLR FKZ 50 WB 9997

  12. Bt Maize Seed Mixtures for Helicoverpa zea (Lepidoptera: Noctuidae): Larval Movement, Development, and Survival on Non-transgenic Maize.

    PubMed

    Burkness, Eric C; Cira, T M; Moser, S E; Hutchison, W D

    2015-12-01

    In 2012 and 2013, field trials were conducted near Rosemount, MN, to assess the movement and development of Helicoverpa zea (Boddie) larvae on non-Bt refuge corn plants within a seed mixture of non-Bt and Bt corn. The Bt corn hybrid expressed three Bt toxins-Cry1Ab, Cry1F, and Vip3A. As the use of seed mixtures for insect resistance management (IRM) continues to be implemented, it is necessary to further characterize how this IRM approach impacts resistance development in ear-feeding Lepidopteran pests. The potential for Bt pollen movement and cross pollination of the non-Bt ears in a seed mixture may lead to Bt toxin exposure to larvae developing on those refuge ears. Larval movement and development by H. zea, feeding on non-Bt refuge plants adjacent to either transgenic Bt or non-Bt plants, were measured to investigate the potential for unintended Bt exposure. Non-Bt plants were infested with H. zea eggs and subplots were destructively sampled twice per week within each treatment to assess larval development, location, and kernel injury. Results indicate that H. zea larval movement between plants is relatively low, ranging from 2-16% of larvae, and occurs mainly after reaching the second instar. Refuge plants in seed mixtures did not produce equivalent numbers of H. zea larvae, kernel injury, and larval development differed as compared with a pure stand of non-Bt plants. This suggests that there may be costs to larvae developing on refuge plants within seed mixtures and additional studies are warranted to define potential impacts. PMID:26318006

  13. Ocean acidification boosts larval fish development but reduces the window of opportunity for successful settlement.

    PubMed

    Rossi, Tullio; Nagelkerken, Ivan; Simpson, Stephen D; Pistevos, Jennifer C A; Watson, Sue-Ann; Merillet, Laurene; Fraser, Peter; Munday, Philip L; Connell, Sean D

    2015-12-22

    Locating appropriate settlement habitat is a crucial step in the life cycle of most benthic marine animals. In marine fish, this step involves the use of multiple senses, including audition, olfaction and vision. To date, most investigations of larval fish audition focus on the hearing thresholds to various frequencies of sounds without testing an ecological response to such sounds. Identifying responses to biologically relevant sounds at the development stage in which orientation is most relevant is fundamental. We tested for the existence of ontogenetic windows of reception to sounds that could act as orientation cues with a focus on vulnerability to alteration by human impacts. Here we show that larvae of a catadromous fish species (barramundi, Lates calcarifer) were attracted towards sounds from settlement habitat during a surprisingly short ontogenetic window of approximately 3 days. Yet, this auditory preference was reversed in larvae reared under end-of-century levels of elevated CO2, such that larvae are repelled from cues of settlement habitat. These future conditions also reduced the swimming speeds and heightened the anxiety levels of barramundi. Unexpectedly, an acceleration of development and onset of metamorphosis caused by elevated CO2 were not accompanied by the earlier onset of attraction towards habitat sounds. This mismatch between ontogenetic development and the timing of orientation behaviour may reduce the ability of larvae to locate habitat or lead to settlement in unsuitable habitats. The misinterpretation of key orientation cues can have implications for population replenishment, which are only exacerbated when ontogenetic development decouples from the specific behaviours required for location of settlement habitats. PMID:26674946

  14. Investigation of the effects of estrogen on skeletal gene expression during zebrafish larval head development

    PubMed Central

    Walker, Benjamin S.; Lassiter, Christopher S.; Jónsson, Zophonías O.

    2016-01-01

    The development of craniofacial skeletal structures requires well-orchestrated tissue interactions controlled by distinct molecular signals. Disruptions in normal function of these molecular signals have been associated with a wide range of craniofacial malformations. A pathway mediated by estrogens is one of those molecular signals that plays role in formation of bone and cartilage including craniofacial skeletogenesis. Studies in zebrafish have shown that while higher concentrations of 17-β estradiol (E2) cause severe craniofacial defects, treatment with lower concentrations result in subtle changes in head morphology characterized with shorter snouts and flatter faces. The molecular basis for these morphological changes, particularly the subtle skeletal effects mediated by lower E2 concentrations, remains unexplored. In the present study we address these effects at a molecular level by quantitative expression analysis of sets of candidate genes in developing heads of zebrafish larvae treated with two different E2 concentrations. To this end, we first validated three suitable reference genes, ppia2, rpl8 and tbp, to permit sensitive quantitative real-time PCR analysis. Next, we profiled the expression of 28 skeletogenesis-associated genes that potentially respond to estrogen signals and play role in craniofacial development. We found E2 mediated differential expression of genes involved in extracellular matrix (ECM) remodelling, mmp2/9/13, sparc and timp2a, as well as components of skeletogenic pathways, bmp2a, erf, ptch1/2, rankl, rarab and sfrp1a. Furthermore, we identified a co-expressed network of genes, including cpn1, dnajc3, esr1, lman1, rrbp1a, ssr1 and tram1 with a stronger inductive response to a lower dose of E2 during larval head development. PMID:27069811

  15. Investigation of the effects of estrogen on skeletal gene expression during zebrafish larval head development.

    PubMed

    Pashay Ahi, Ehsan; Walker, Benjamin S; Lassiter, Christopher S; Jónsson, Zophonías O

    2016-01-01

    The development of craniofacial skeletal structures requires well-orchestrated tissue interactions controlled by distinct molecular signals. Disruptions in normal function of these molecular signals have been associated with a wide range of craniofacial malformations. A pathway mediated by estrogens is one of those molecular signals that plays role in formation of bone and cartilage including craniofacial skeletogenesis. Studies in zebrafish have shown that while higher concentrations of 17-β estradiol (E 2) cause severe craniofacial defects, treatment with lower concentrations result in subtle changes in head morphology characterized with shorter snouts and flatter faces. The molecular basis for these morphological changes, particularly the subtle skeletal effects mediated by lower E 2 concentrations, remains unexplored. In the present study we address these effects at a molecular level by quantitative expression analysis of sets of candidate genes in developing heads of zebrafish larvae treated with two different E 2 concentrations. To this end, we first validated three suitable reference genes, ppia2, rpl8 and tbp, to permit sensitive quantitative real-time PCR analysis. Next, we profiled the expression of 28 skeletogenesis-associated genes that potentially respond to estrogen signals and play role in craniofacial development. We found E 2 mediated differential expression of genes involved in extracellular matrix (ECM) remodelling, mmp2/9/13, sparc and timp2a, as well as components of skeletogenic pathways, bmp2a, erf, ptch1/2, rankl, rarab and sfrp1a. Furthermore, we identified a co-expressed network of genes, including cpn1, dnajc3, esr1, lman1, rrbp1a, ssr1 and tram1 with a stronger inductive response to a lower dose of E 2 during larval head development. PMID:27069811

  16. Ethanol Affects the Development of Sensory Hair Cells in Larval Zebrafish (Danio rerio)

    PubMed Central

    Matsui, Jonathan I.

    2013-01-01

    Children born to mothers with substantial alcohol consumption during pregnancy can present a number of morphological, cognitive, and sensory abnormalities, including hearing deficits, collectively known as fetal alcohol syndrome (FAS). The goal of this study was to determine if the zebrafish lateral line could be used to study sensory hair cell abnormalities caused by exposure to ethanol during embryogenesis. Some lateral line sensory hair cells are present at 2 days post-fertilization (dpf) and are functional by 5 dpf. Zebrafish embryos were raised in fish water supplemented with varying concentrations of ethanol (0.75%–1.75% by volume) from 2 dpf through 5 dpf. Ethanol treatment during development resulted in many physical abnormalities characteristic of FAS in humans. Also, the number of sensory hair cells decreased as the concentration of ethanol increased in a dose-dependent manner. The dye FM 1-43FX was used to detect the presence of functional mechanotransduction channels. The percentage of FM 1-43-labeled hair cells decreased as the concentration of ethanol increased. Methanol treatment did not affect the development of hair cells. The cell cycle markers proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU) demonstrated that ethanol reduced the number of sensory hair cells, as a consequence of decreased cellular proliferation. There was also a significant increase in the rate of apoptosis, as determined by TUNEL-labeling, in neuromasts following ethanol treatment during larval development. Therefore, zebrafish are a useful animal model to study the effects of hair cell developmental disorders associated with FAS. PMID:24324841

  17. Proteome analysis of hemolymph changes during the larval to pupal development stages of honeybee workers (Apis mellifera ligustica).

    PubMed

    Woltedji, Dereje; Fang, Yu; Han, Bin; Feng, Mao; Li, Rongli; Lu, Xiaoshan; Li, Jianke

    2013-11-01

    Hemolymph is vital for the flow and transportation of nutrients, ions, and hormones in the honey bee and plays role in innate immune defense. The proteome of the hemolymph changes over the life of a honey bee, but many of these changes are not well characterized, including changes during the life cycle transition from the larval to pupal stages of workers. We used two-dimensional gel electrophoresis, mass spectrometry, bioinformatics, and Western blot to analyze the proteome changes of the honeybee hemolymph during the transition from newly hatched larvae to five-day-old pupae. Of the 49 nonredundant proteins that changed in abundance (identified by 80 protein spots), 29 (59.2%) and 20 (40.8%) were strongly expressed in the larvae and the pupae, respectively. The larval hemolymph had high expressions of major royal jelly proteins and proteins related to metabolism of carbohydrates and energy, folding activities, development, and the cytoskeleton and antioxidant systems. Proteins involved in food storage and the metabolism of fatty acids and amino acids were abundantly expressed during the late larval to pupal development stages. The proteins expressed by the young larvae are used to enhance their development process and as a temporal innate immune protection mechanism until they gain immunity with age development. The pupae use more energy storage related proteins as they prepare for their non-diet-driven pupation. Our data provide new evidence that changes in the hemolymph at the proteome level match the processes during life transitions in the honeybee. PMID:24006915

  18. Reproduction and development in Halocaridina rubra Holthuis, 1963 (Crustacea: Atyidae) clarifies larval ecology in the Hawaiian anchialine ecosystem.

    PubMed

    Havird, Justin C; Vaught, Rebecca C; Weese, David A; Santos, Scott R

    2015-10-01

    Larvae in aquatic habitats often develop in environments different from those they inhabit as adults. Shrimp in the Atyidae exemplify this trend, as larvae of many species require salt or brackish water for development, while adults are freshwater-adapted. An exception within the Atyidae family is the "anchialine clade," which are euryhaline as adults and endemic to habitats with subterranean fresh and marine water influences. Although the Hawaiian anchialine atyid Halocaridina rubra is a strong osmoregulator, its larvae have never been observed in nature. Moreover, larval development in anchialine species is poorly studied. Here, reproductive trends in laboratory colonies over a 5-y period are presented from seven genetic lineages and one mixed population of H. rubra; larval survivorship under varying salinities is also discussed. The presence and number of larvae differed significantly among lineages, with the mixed population being the most prolific. Statistical differences in reproduction attributable to seasonality also were identified. Larval survivorship was lowest (12% settlement rate) at a salinity approaching fresh water and significantly higher in brackish and seawater (88% and 72%, respectively). Correlated with this finding, identifiable gills capable of ion transport did not develop until metamorphosis into juveniles. Thus, early life stages of H. rubra are apparently excluded from surface waters, which are characterized by lower and fluctuating salinities. Instead, these stages are restricted to the subterranean (where there is higher and more stable salinity) portion of Hawaii's anchialine habitats due to their inability to tolerate low salinities. Taken together, these data contribute to the understudied area of larval ecology in the anchialine ecosystem. PMID:26504154

  19. Yolk-sac larval development of the substrate-brooding cichlid Archocentrus nigrofasciatus in relation to temperature.

    PubMed

    Vlahos, Nikolaos; Vasilopoulos, Michael; Mente, Eleni; Hotos, George; Katselis, George; Vidalis, Kosmas

    2015-09-01

    In order to conserve and culture the cichlid fish Archocentrus nigrofasciatus, more information about its reproductive biology and its larval behavior and morphogenesis is necessary. Currently, temperatures ranging from 21 to 27 °C are used in ornamental aquaculture hatcheries. Lower temperatures are preferred to reduce the costs of water heating, and 23 °C is usually the selected temperature. However, there is limited information on culturing protocols for ornamental species and most of the information generated on this topic remains scarce. Thus, the present study examines the morphological development of Archocentrus nigrofasciatus during the yolk-sac period up to the age of 100 h post-hatching in relation to 2 temperature regimes used in ornamental aquaculture: a temperature of 27 °C (thermal optimum) and a decreased temperature of 23 °C (thermal tolerance). The results of this study suggest that the 27 °C temperature generates intense morphological changes in yolk-sac development in a shorter period. This has advantages as it reduces the time of yolk-sac larval development, and, thus, minimizes the transition phase to exogenous feeding and maximizes the efficiency at which yolk is converted into body tissues. The present paper provides necessary information to produce freshwater ornamental fish with better practices so as to increase larval survival and capitalize on time for growth. PMID:26201370

  20. Inbreeding Effects in Families of Ostrinia nubilalis (Lepidoptera: Crambidae): Larval Development in Laboratory Bioassays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inbreeding depression of laboratory-reared insects has the potential to affect their larval performance and reproductive output. Two studies of laboratory-reared colonies of Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae) were conducted to assess whether inbreeding affected a laboratory bioass...

  1. Gonadosomatic mosaicism for lethal mutations in Drosophila lethal mutations disturbing larval development

    SciTech Connect

    Ivanov, A.I.; Sakharova, N.Yu.

    1988-11-01

    Phenogenetic analysis of autonomous lethal mutations obtained by the method of gonadosomatic mosaicism which manifested during larval stages, established that the nuclei of hypodermal cells, salivary glands suprapharyngeal ganglion, pharynx, esophagus, gizzard, and hindgut are the derivatives of the same nucleus (from the first two nuclei of cleavage) as the nuclei of the cells of the imaginal-somatic tissues.

  2. Efficacy and longevity of the newly developed catnip oil microcapsules against stable fly oviposition larval growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is one of the most important pests of cattle and costs U.S. cattle producers billions of dollars in losses annually. In this study, the efficacy of catnip oil encapsulated in gelatin in oviposition deterrence and larval growth inhibition in st...

  3. Efficacy and longevity of newly developed catnip oil microcapsules against stable fly oviposition and larval growth.

    PubMed

    Zhu, J J; Wienhold, B J; Wehrle, J; Davis, D; Chen, H; Taylor, D; Friesen, K; Zurek, L

    2014-06-01

    The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is one of the most important pests of cattle and costs U.S. cattle producers billions of dollars in losses annually. In this study, the efficacy of catnip oil encapsulated in gelatin in oviposition deterrence and larval growth inhibition in stable flies was examined under laboratory conditions. More than 98% inhibition of stable fly larval growth and female oviposition was observed in larval and oviposition media treated with encapsulated catnip oil (0.5 g). Further, dose-response tests showed that as little as 0.1 g of encapsulated catnip oil provided > 85% oviposition deterrence. The release of nepetalactones from the capsules was more rapid when the capsules were placed on a moist substrate rather than a dry substrate. Encapsulated catnip oil also exhibited antibacterial activity, supporting the hypothesis that its inhibition of larval growth may be based on its killing of the bacteria on which larvae feed. The use of encapsulated catnip oil can provide an alternative control strategy for stable fly management. PMID:24111783

  4. Dispersal of stable flies (Diptera: Muscidae) from larval development sites in a Nebraska landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven mark recapture studies of stable flies wer conducted in a mixed agricultural environment in northeastern Nebraska. Larval developmental sites were marked by dusting the surface with fluorescent pigments and stable flies were recaptured with grids of Alsynite sticky traps. Recaptured flies were...

  5. Development of a recombinant protein-based ELISA for diagnosis of larval cyathostomin infection.

    PubMed

    Mitchell, Mairi C; Tzelos, Thomas; Handel, Ian; McWilliam, Hamish E G; Hodgkinson, Jane E; Nisbet, Alasdair J; Kharchenko, Vitaliy O; Burgess, Stewart T G; Matthews, Jacqueline B

    2016-07-01

    Cyathostomins are ubiquitous nematodes of horses. Once ingested, they can spend a substantial time as encysted larvae in the intestinal wall. The larvae can comprise up to 90% of the total burden, with up to several million worms reported in individuals. These stages can emerge in large numbers to cause life-threatening colitis. Direct methods for detection of encysted larval burdens in live horses do not exist. Previously, two antigen complexes were identified as promising markers for infection. A component of these, cyathostomin gut associated larval antigen-1 (Cy-GALA-1), was identified following immunoscreening of a complementary DNA library. Serum immunoglobulin G(T) (IgG(T)) responses to Cy-GALA-1 were shown to inform on larval infection. Sequence analysis of polymerase chain reaction products amplified from individual worms indicated that Cy-GALA-1 was derived from Cyathostomum pateratum. As cyathostomin infections always comprise multiple species, a diagnostic test must account for this. Here, segments of the Cy-gala gene were isolated from four common species, Cyathostomum catinatum, Cylicocyclus ashworthi, Cylicostephanus goldi and Cylicostephanus longibursatus, and the associated proteins expressed in recombinant form. The specificity and immunogenicity of each protein was confirmed. Each protein was assessed by enzyme linked immuno sorbent assay (ELISA) for its ability for informing on the presence of encysted larval infection and the level of burden. PMID:27174468

  6. Control of larval and egg development in Aedes aegypti with RNA interference against juvenile hormone acid methyl transferase.

    PubMed

    Van Ekert, Evelien; Powell, Charles A; Shatters, Robert G; Borovsky, Dov

    2014-11-01

    RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including mosquitoes and many other insects. Little has been done, however, to harness this approach in order to control adult and larval mosquitoes. Juvenile hormone (JH) plays a pivotal role in the control of reproduction in adults and metamorphism in larval mosquitoes. This report describes an approach to control Aedes aegypti using RNAi against JH acid methyl transferase (AeaJHAMT), the ultimate enzyme in the biosynthetic pathway of JH III that converts JH acid III (JHA III) into JH III. In female A. aegypti that were injected or fed jmtA dsRNA targeting the AeaJHAMT gene (jmtA) transcript, egg development was inhibited in 50% of the treated females. In mosquito larvae that were fed transgenic Pichia pastoris cells expressing long hair pin (LHP) RNA, adult eclosion was delayed by 3 weeks causing high mortality. Northern blot analyses and qPCR studies show that jmtA dsRNA causes inhibition of jmtA transcript in adults and larvae, which is consistent with the observed inhibition of egg maturation and larval development. Taken together, these results suggest that jmtA LHP RNA expressed in heat inactivated genetically modified P. pastoris cells could be used to control mosquito populations in the marsh. PMID:25111689

  7. Effect of CO2-related acidification on aspects of the larval development of the European lobster, Homarus gammarus (L.)

    NASA Astrophysics Data System (ADS)

    Arnold, K. E.; Findlay, H. S.; Spicer, J. I.; Daniels, C. L.; Boothroyd, D.

    2009-03-01

    Oceanic uptake of anthropogenic CO2 results in a reduction in pH termed "Ocean Acidification" (OA). Comparatively little attention has been given to the effect of OA on the early life history stages of marine animals. Consequently, we investigated the effect of culture in CO2-acidified sea water (approx. 1200 ppm, i.e. average values predicted using IPCC 2007 A1F1 emissions scenarios for year 2100) on early larval stages of an economically important crustacean, the European lobster Homarus gammarus. Culture in CO2-acidified sea water did not significantly affect carapace length or development of H. gammarus. However, there was a reduction in carapace mass during the final stage of larval development in CO2-acidified sea water. This co-occurred with a reduction in exoskeletal mineral (calcium and magnesium) content of the carapace. As the control and high CO2 treatments were not undersaturated with respect to any of the calcium carbonate polymorphs measured, the physiological alterations we record are most likely the result of acidosis or hypercapnia interfering with normal homeostatic function, and not a direct impact on the carbonate supply-side of calcification per se. Thus despite there being no observed effect on survival, carapace length, or zoeal progression, OA related (indirect) disruption of calcification and carapace mass might still adversely affect the competitive fitness and recruitment success of larval lobsters with serious consequences for population dynamics and marine ecosystem function.

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

    SciTech Connect

    Neumann, C.J.; Cohen, S.M.

    1996-04-01

    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 wg{sup ts} 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. 31 refs., 6 figs., 1 tab.

  9. The Implications of Temperature-Mediated Plasticity in Larval Instar Number for Development within a Marine Invertebrate, the Shrimp Palaemonetes varians

    PubMed Central

    Oliphant, Andrew; Hauton, Chris; Thatje, Sven

    2013-01-01

    Variations in larval instar number are common among arthropods. Here, we assess the implications of temperature-mediated variations in larval instar number for larval development time, larval growth rates, and juvenile dry weight within the palaemonid shrimp, Palaemonetes varians. In contrast with previous literature, which focuses on terrestrial arthropods, particularly model and pest species often of laboratory lines, we use wild shrimp, which differ in their life history from previous models. Newly-hatched P. varians larvae were first reared at 5, 10, 17, 25, and 30°C to assess their thermal scope for development. Larvae developed at 17, 25, and 30°C. At higher temperatures, larvae developed through fewer larval instars. Two dominant developmental pathways were observed; a short pathway of four instars and a long pathway of five instars. Longer developmental pathways of six to seven instars were rarely observed (mostly at lower temperatures) and consisted of additional instars as ‘repeat’ instars; i.e. little developmental advance over the preceding instar. To assess the implications of temperature-mediated variation in larval instar number, newly-hatched larvae were then reared at 15, 20, and 25°C. Again, the proportion of larvae developing through four instars increased with temperature. At all temperatures, larval development time and juvenile dry weight were greater for larvae developing through five instars. Importantly, because of the increasing proportion of larvae developing through four instars with increasing temperature, larval traits associated with this pathway (reduced development time and juvenile dry weight) became more dominant. As a consequence of increasing growth rate with temperature, and the shift in the proportion of larvae developing through four instars, juvenile dry weight was greatest at intermediate temperatures (20°C). We conclude that at settlement P. varians juveniles do not follow the temperature-size rule; this is of

  10. Regional immune responses with stage-specific antigen recognition profiles develop in lymph nodes of pigs following Ascaris suum larval migration.

    PubMed

    Jungersen, G; Eriksen, L; Nansen, P; Lind, P; Rasmussen, T; Meeusen, E N

    2001-04-01

    The early life-cycle of the pig round worm, Ascaris suum, involves well-defined larval development in the liver, lungs and finally the small intestine. Distinct regional immune responses to larval antigens of A. suum were observed in the draining lymph nodes of immunized and challenged pigs during larval migration. This was reflected in a transient enlargement of the stimulated lymph nodes, due to increases in numbers of B cells and CD4 T cells, and the production of A. suum-specific antibody by antibody secreting cell (ASC) cultures. Larval antigen recognition pattern of antibodies in serum, bile and draining lymph node ASC culture supernatant (ASC-probes) was examined by immunoblotting. This revealed distinct organ-specific recognition patterns of larval-specific antigens by the draining lymph nodes at different times after challenge. In particular, an early larval 42 kDa antigen was recognized specifically by ASC-probes of the liver lymph nodes at 7 but not 14 days postchallenge (pc) which was not detected in other lymph nodes, serum or bile of the same pig. Similarly, a late larval antigen of 34 kDa was uniquely detected by lung and jejunal ASC-probes at 14 days pc. These observations demonstrate how development of distinct regional immune responses in tissues with different antigen stimulation can be monitored with ASC-probes and flow cytometry. PMID:11298295

  11. Phosphoproteome analysis during larval development and metamorphosis in the spionid polychaete Pseudopolydora vexillosa

    PubMed Central

    2011-01-01

    Background The metamorphosis of the spionid polychaete Pseudopolydora vexillosa includes spontaneous settlement onto soft-bottom habitats and morphogenesis that can be completed in a very short time. A previous study on the total changes to the proteome during the various developmental stages of P. vexillosa suggested that little or no de novo protein synthesis occurs during metamorphosis. In this study, we used multicolor fluorescence detection of proteins in 2-D gels for differential analysis of proteins and phosphoproteins to reveal the dynamics of post-translational modification proteins in this species. A combination of affinity chromatography, 2D-PAGE, and mass spectrometry was used to identify the phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles. Results We reproducibly detected 210, 492, and 172 phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles, respectively. The highest percentage of phosphorylation was observed during the competent larval stage. About 64 stage-specific phosphoprotein spots were detected in the competent stage, and 32 phosphoproteins were found to be significantly differentially expressed in the three stages. We identified 38 phosphoproteins, 10 of which were differentially expressed during metamorphosis. These phosphoproteins belonged to six categories of biological processes: (1) development, (2) cell differentiation and integrity, (3) transcription and translation, (4) metabolism, (5) protein-protein interaction and proteolysis, and (6) receptors and enzymes. Conclusion This is the first study to report changes in phosphoprotein expression patterns during the metamorphosis of the marine polychaete P. vexillosa. The higher degree of phosphorylation during the process of attaining competence to settle and metamorphose may be due to fast morphological transitions regulated by various mechanisms. Our data are consistent with previous studies showing a

  12. Interactions of temperature and steroids on larval growth, development, and metamorphosis in a toad (Bufo boreas).

    PubMed

    Hayes, T; Chan, R; Licht, P

    1993-07-01

    The effects of temperature and steroids [testosterone (T), estradiol (E2), and corticosterone (B)] on premetamorphic growth and development were investigated in the toad (Bufo boreas). The effects of steroids were both temperature and age dependent. In the first experiment, steroids (1.1-1.4 microM) were administered by dissolving them in the water beginning 1 day after hatching at 22 degrees C or 27 degrees C. At 22 degrees C, B inhibited growth (P < 0.001) but had no significant effect on development. Forelegs never emerged in B-treated animals and all died before complete tail resorption. Discontinuation of B treatment allowed normal growth and metamorphosis, but the resulting post-metamorphic animals were significantly shorter (snout-vent length, P < 0.001) than after other treatments. At 22 degrees C, T and E2 had no effect on larval growth and development or size at metamorphosis (P > 0.05), but T induced early foreleg emergence (FLE) (P < 0.005). At 27 degrees C, B was fatal after 2 weeks of treatment, and T and E2 inhibited growth (P < 0.001) and development (P < 0.001), but did not affect time to FLE. In a second experiment at 27 degrees C, treatment with 1.1 microM B starting 15 days after hatching induced early metamorphic events (P < 0.001), such as tail resorption and emergence of the left foreleg (but not the right), but jaw and head restructuring failed to occur. All B-treated animals died before complete tail resorption. In a third experiment, 0.275 and 1.11 microM B, starting at day 43 (stage 43), induced early FLE (P < 0.05) and decreased snout-vent length at tail resorption (P < 0.005) without a dose effect. A higher dose of B (4.44 microM) decreased snout-vent length at tail resorption and time to FLE (P < 0.05) but did not affect body weight at metamorphosis (P > 0.05). Animals in this experiment survived to complete tail resorption and transformed normally. The actions of B in these experiments closely resemble those observed with

  13. Mosquito larval habitat mapping using remote sensing and GIS: Implications of coalbed methane development and West Nile virus

    SciTech Connect

    Zou, L.; Miller, S.N.; Schmidtmann, E.T.

    2006-09-15

    Potential larval habitats of the mosquito Culex tarsalis (Coquillett), implicated as a primary vector of West Nile virus in Wyoming, were identified using integrated remote sensing and geographic information system (GIS) analyses. The study area is in the Powder River Basin of north central Wyoming, an area that has been undergoing a significant increase in coalbed methane gas extractions since the late 1990s. Large volumes of water are discharged, impounded, and released during the extraction of methane gas, creating aquatic habitats that have the potential to support immature mosquito development. Landsat TM and ETM + data were initially classified into spectrally distinct water and vegetation classes, which were in turn used to identify suitable larval habitat sites. This initial habitat classification was refined using knowledge-based GIS techniques requiring spatial data layers for topography, streams, and soils to reduce the potential for overestimation of habitat. Accuracy assessment was carried out using field data and high-resolution aerial photography commensurate with one of the Landsat images. The classifier can identify likely habitat for ponds larger than 0.8 ha (2 acres) with generally satisfactory results (72.1%) with a lower detection limit of approximate to 0.4 ha (1 acre). Results show a 75% increase in potential larval habitats from 1999 to 2004 in the study area, primarily because of the large increase in small coalbed methane water discharge ponds. These results may facilitate mosquito abatement programs in the Powder River Basin with the potential for application throughout the state and region.

  14. Effect of CO2-related acidification on aspects of the larval development of the European lobster, Homarus gammarus (L.)

    NASA Astrophysics Data System (ADS)

    Arnold, K. E.; Findlay, H. S.; Spicer, J. I.; Daniels, C. L.; Boothroyd, D.

    2009-08-01

    Oceanic uptake of anthropogenic CO2 results in a reduction in pH termed "Ocean Acidification" (OA). Comparatively little attention has been given to the effect of OA on the early life history stages of marine animals. Consequently, we investigated the effect of culture in CO2-acidified sea water (approx. 1200 ppm, i.e. average values predicted using IPCC 2007 A1F1 emissions scenarios for year 2100) on early larval stages of an economically important crustacean, the European lobster Homarus gammarus. Culture in CO2-acidified sea water did not significantly affect carapace length of H. gammarus. However, there was a reduction in carapace mass during the final stage of larval development in CO2-acidified sea water. This co-occurred with a reduction in exoskeletal mineral (calcium and magnesium) content of the carapace. As the control and high CO2 treatments were not undersaturated with respect to any of the calcium carbonate polymorphs measured, the physiological alterations we record are most likely the result of acidosis or hypercapnia interfering with normal homeostatic function, and not a direct impact on the carbonate supply-side of calcification per se. Thus despite there being no observed effect on survival, carapace length, or zoeal progression, OA related (indirect) disruption of calcification and carapace mass might still adversely affect the competitive fitness and recruitment success of larval lobsters with serious consequences for population dynamics and marine ecosystem function.

  15. Development and organization of the larval nervous system in Phoronopsis harmeri: new insights into phoronid phylogeny

    PubMed Central

    2014-01-01

    Background The organization and development of the nervous system has traditionally been used as an important character for establishing the relationships among large groups of animals. According to this criterion, phoronids were initially regarded as deuterostomian but have more recently been regarded as protostomian. The resolving of this conflict requires detailed information from poorly investigated members of phoronids, such as Phoronopsis harmeri. Results The serotonin-like immunoreactive part of the P. harmeri nervous system changes during larval development. These changes mostly concern the nervous system of the hood and correlate with the appearance of the median and two marginal neurite bundles, the frontal organ, and the sensory field. The apical organ has bilateral symmetry. The tentacular neurite bundle passes under the tentacles, contains several types of perikarya, and gives rise to intertentacular bundles, which branch in the tentacle base and penetrate into adjacent tentacles by two lateroabfrontal bundles. There are two groups of dorsolateral perikarya, which exhibit serotonin-like immunoreactivity, contact the tentacular neurite bundle, and are located near the youngest tentacles. Larvae have a minor nerve ring, which originates from the posterior marginal neurite bundle of the hood, passes above the tentacle base, and gives rise to the mediofrontal neurite bundle in each tentacle. Paired laterofrontal neurite bundles of tentacles form a continuous nerve tract that conducts to the postoral ciliated band. Discussion The organization of the nervous system differs among the planktotrophic larvae of phoronid species. These differences may correlate with differences in phoronid biology. Data concerning the innervation of tentacles in different phoronid larvae are conflicting and require careful reinvestigation. The overall organization of the nervous system in phoronid larvae has more in common with the deuterostomian than with the protostomian

  16. Developing methods based on light sheet fluorescence microscopy for biophysical investigations of larval zebrafish

    NASA Astrophysics Data System (ADS)

    Taormina, Michael J.

    Adapting the tools of optical microscopy to the large-scale dynamic systems encountered in the development of multicellular organisms provides a path toward understanding the physical processes necessary for complex life to form and function. Obtaining quantitatively meaningful results from such systems has been challenging due to difficulty spanning the spatial and temporal scales representative of the whole, while also observing the many individual members from which complex and collective behavior emerges. A three-dimensional imaging technique known as light sheet fluorescence microscopy provides a number of significant benefits for surmounting these challenges and studying developmental systems. A thin plane of fluorescence excitation light is produced such that it coincides with the focal plane of an imaging system, providing rapid acquisition of optically sectioned images that can be used to construct a three-dimensional rendition of a sample. I discuss the implementation of this technique for use in larva of the model vertebrate Danio rerio (zebrafish). The nature of light sheet imaging makes it especially well suited to the study of large systems while maintaining good spatial resolution and minimizing damage to the specimen from excessive exposure to excitation light. I show the results from a comparative study that demonstrates the ability to image certain developmental processes non-destructively, while in contrast confocal microscopy results in abnormal growth due to phototoxicity. I develop the application of light sheet microscopy to the study of a previously inaccessible system: the bacterial colonization of a host organism. Using the technique, we are able to obtain a survey of the intestinal tract of a larval zebrafish and observe the location of microbes as they grow and establish a stable population in an initially germ free fish. Finally, I describe a new technique to measure the fluid viscosity of this intestinal environment in vivo using

  17. The Impact of Seawater Saturation State on Early Skeletal Development in Larval Corals: Insights into Scleractinian Biomineralization

    NASA Astrophysics Data System (ADS)

    Cohen, A. L.; McCorkle, D. C.; de Putron, S.

    2007-12-01

    contrast to the fine, closed, densely packed spherulitic bundles accreted in the control system, larvae in the lower Omega treatments produced a disorganized conglomerate of large, highly faceted crystals, consistent with slow growth under low saturation state conditions. Our results suggest that the coral calcification response to changes in seawater saturation state is linked to a physiological limitation on the organism's ability to elevate the saturation state of seawater within the calcifying space. Further, our data indicate that ocean acidification due to fossil fuel CO2 emissions will likely have a strong negative effect on the recruitment and early skeletal development of larval corals over the next several decades.

  18. Stage-Specific Changes in Physiological and Life-History Responses to Elevated Temperature and Pco2 during the Larval Development of the European Lobster Homarus gammarus (L.).

    PubMed

    Small, Daniel P; Calosi, Piero; Boothroyd, Dominic; Widdicombe, Steve; Spicer, John I

    2015-01-01

    An organism's physiological processes form the link between its life-history traits and the prevailing environmental conditions, especially in species with complex life cycles. Understanding how these processes respond to changing environmental conditions, thereby affecting organismal development, is critical if we are to predict the biological implications of current and future global climate change. However, much of our knowledge is derived from adults or single developmental stages. Consequently, we investigated the metabolic rate, organic content, carapace mineralization, growth, and survival across each larval stage of the European lobster Homarus gammarus, reared under current and predicted future ocean warming and acidification scenarios. Larvae exhibited stage-specific changes in the temperature sensitivity of their metabolic rate. Elevated Pco2 increased C∶N ratios and interacted with elevated temperature to affect carapace mineralization. These changes were linked to concomitant changes in survivorship and growth, from which it was concluded that bottlenecks were evident during H. gammarus larval development in stages I and IV, the transition phases between the embryonic and pelagic larval stages and between the larval and megalopa stages, respectively. We therefore suggest that natural changes in optimum temperature during ontogeny will be key to larvae survival in a future warmer ocean. The interactions of these natural changes with elevated temperature and Pco2 significantly alter physiological condition and body size of the last larval stage before the transition from a planktonic to a benthic life style. Thus, living and growing in warm, hypercapnic waters could compromise larval lobster growth, development, and recruitment. PMID:26658247

  19. Effect of benserazid and 6-hydroxydopamine on the development of the last larval instar of the house cricket, Acheta domestica L.

    PubMed

    Rózsa, K S; Chudakova, I V; Hiripi, L

    1986-01-01

    The effect of benserazid and 6-OHDA on the duration of the last larval instar and development of wings with intact corpora allata and following allatectomy on Acheta domestica L. was studied. 6-OHDA failed to alter the duration of the last larval instar in the nymphs with intact corpora allata but prolonged it in the allatectomized crickets. Introduction of 6-OHDA in the second phase of the last larval instar caused a deformation of the wings both in allatectomized and intact crickets. Injection of benserazid to the nymphs of the last larval instar prolonged the duration of this phase only in the presence of the corpora allata. The effect of benserazid can be connected to elimination of central inhibition of the corpora allata involving dopaminergic neurons of the brain. PMID:2869911

  20. Expression profile of heat shock response factors during hookworm larval activation and parasitic development.

    PubMed

    Gelmedin, Verena; Delaney, Angela; Jennelle, Lucas; Hawdon, John M

    2015-07-01

    protein expression, slightly down regulated both genes under similar conditions. Both modulators inhibited activation-associated feeding, but neither had an effect on hsp-1 levels in activated L3 at 16h. Both celastrol and KNK437 prevent the up-regulation of daf-21 and hsf-1 seen in non-activated control larvae during activation, and significantly down regulated expression of the HSF-1 negative regulator Aca-hsb-1 in activated larvae. Expression levels of heat shock response factors were examined in developing Ancylostoma ceylanicum larvae recovered from infected hosts and found to differ significantly from the expression profile of activated L3, suggesting that feeding during in vitro activation is regulated differently than parasitic development. Our results indicate that a classical heat shock response is not induced at host temperature and is suppressed during larval recovery and parasitic development in the host, but a partial heat shock response is induced after extended incubation at host temperature in the absence of a developmental signal, possibly to protect against heat stress. PMID:26296769

  1. Experimental study of Lucilia sericata (Diptera Calliphoridae) larval development on rat cadavers: Effects of climate and chemical contamination.

    PubMed

    Aubernon, Cindy; Charabidzé, Damien; Devigne, Cédric; Delannoy, Yann; Gosset, Didier

    2015-08-01

    Household products such as bleach, gasoline or hydrochloric acid have been used to mask the presence of a cadaver or to prevent the colonization of insects. These types of chemicals affect insect development and alter the forensic entomology analysis. This study was designed to test the effects of six household products (bleach, mosquito repellent, perfume, caustic soda, insecticide and unleaded gasoline) on blowfly (Lucilia sericata, Diptera: Calliphoridae) larval development. Furthermore, the effects of climate (rain or dry conditions) on larval development were analyzed. For each replication, 100 first instars were placed on a rat cadaver on which one household product was spilled. We observed a decrease in the survival rates of the larvae but no significant effect on their development times or the adult size. The same trends were observed under rainy conditions. However, the rain altered the effects of some tested household products, especially gasoline. These results demonstrate for the first time the successful development of necrophagous larvae on chemically contaminated cadavers, and provide evidence for the range of possible effects to expect. PMID:26123620

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

    PubMed

    Isogai, S; Horiguchi, M; Weinstein, B M

    2001-02-15

    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. PMID:11161578

  3. Effect of mercuric chloride on fertilization and larval development in the River Frog, Rana heckscheri (Wright) (Anura: Ranidae)

    SciTech Connect

    Punzo, F. )

    1993-10-01

    Previous investigations have indicated that heavy metals such as copper, cadmium, lead and mercury can act as systemic toxicants in many species of wildlife. Although numerous studies have emphasized the effects of metals and pesticides on metabolism, growth, survivorship, neural processes and reproduction in a number of taxa, little information is available on the effects of sublethal concentrations of metals on the reproductive physiology of amphibians. Industrial processes and mining activities can release substantial concentrations of heavy metals such as mercury into aquatic habitats. Since most amphibians have obligate aquatic larval stages, they are exposed to pollutants discharged into the aquatic environment. Amphibians can act as accumulators of heavy metals and their larval stages are useful indicators of pollution levels in the field. What little data are available, indicate that metals can significantly reduce viability in amphibians through their actions on metabolism, development and gametogenesis. The recent concerns over worldwide declines in amphibian populations and the susceptibility of amphibian populations to environmental toxicants, led me to assess the effect of mercuric chloride, one of the most common and persistent toxicants in aquatic environments, on fertilization and larval development in the river frog, Rana heckscheri (Wright). Although there is some information on fish, very little data are available on the effects of mercury on fertilization in amphibians generally, and no published data exist for R. heckscheri. This species is a conspicuous component of the aquatic fauna of parts of the southeastern United States where mercury levels have increased significantly over the last two decades. 22 refs., 2 tabs.

  4. Patterns of growth and tract formation during the early development of secondary lineages in the Drosophila larval brain.

    PubMed

    Lovick, Jennifer K; Kong, Angel; Omoto, Jaison J; Ngo, Kathy T; Younossi-Hartenstein, Amelia; Hartenstein, Volker

    2016-04-01

    The Drosophila brain consists of a relatively small number of invariant, genetically determined lineages which provide a model to study the relationship between gene function and neuronal architecture. In following this long-term goal, we reconstruct the morphology (projection pattern and connectivity) and gene expression patterns of brain lineages throughout development. In this article, we focus on the secondary phase of lineage morphogenesis, from the reactivation of neuroblast proliferation in the first larval instar to the time when proliferation ends and secondary axon tracts have fully extended in the late third larval instar. We have reconstructed the location and projection of secondary lineages at close (4 h) intervals and produced a detailed map in the form of confocal z-projections and digital three-dimensional models of all lineages at successive larval stages. Based on these reconstructions, we could compare the spatio-temporal pattern of axon formation and morphogenetic movements of different lineages in normal brain development. In addition to wild type, we reconstructed lineage morphology in two mutant conditions. (1) Expressing the construct UAS-p35 which rescues programmed cell death we could systematically determine which lineages normally lose hemilineages to apoptosis. (2) so-Gal4-driven expression of dominant-negative EGFR ablated the optic lobe, which allowed us to conclude that the global centrifugal movement normally affecting the cell bodies of lateral lineages in the late larva is causally related to the expansion of the optic lobe, and that the central pattern of axonal projections of these lineages is independent of the presence or absence of the optic lobe. PMID:26178322

  5. Transcription factor broad suppresses precocious development of adult structures during larval-pupal metamorphosis in the red flour beetle, Tribolium castaneum.

    PubMed

    Parthasarathy, R; Tan, A; Bai, H; Palli, Subba R

    2008-01-01

    Broad (br), a transcription factor containing the Broad-Tramtrack-Bric-a-brac (BTB) and zinc finger domains was shown to mediate 20-hydroxyecdysone (20E) action and pupal development in Drosophila melanogaster and Manduca sexta. We determined the key roles of br during larval-pupal metamorphosis using RNA interference (RNAi) in a coleopteran insect, Tribolium castaneum. Two major peaks of T. castaneum broad (Tcbr) mRNA, one peak at the end of feeding stage prior to the larvae entering the quiescent stage and another peak during the quiescent stage were detected in the whole body and midgut tissue dissected from staged insects. Expression of br during the final instar larval stage is essential for successful larval-pupal metamorphosis, because, RNAi-mediated knock-down of Tcbr during this stage derailed larval-pupal metamorphosis and produced insects that showed larval, pupal and adult structures. Tcbr dsRNA injected into the final instar larvae caused reduction in the mRNA levels of genes known to be involved in 20E action (EcRA, E74 and E75B). Tcbr dsRNA injected into the final instar larvae also caused an increase in the mRNA levels of JH-response genes (JHE and Kr-h1b). Knock-down of Tcbr expression also affected 20E-mediated remodeling of midgut during larval-pupal metamorphosis. These data suggest that the expression of Tcbr during the final instar larval stage promotes pupal program while suppressing the larval and adult programs ensuring a transitory pupal stage in holometabolous insects. PMID:18083350

  6. Overcrowding-mediated stress alters cell proliferation in key neuroendocrine areas during larval development in Rhinella arenarum.

    PubMed

    Distler, Mijal J; Jungblut, Lucas D; Ceballos, Nora R; Paz, Dante A; Pozzi, Andrea G

    2016-02-01

    Exposure to adverse environmental conditions can elicit a stress response, which results in an increase in endogenous corticosterone levels. In early life stages, it has been thoroughly demonstrated that amphibian larval growth and development is altered as a consequence of chronic stress by interfering with the metamorphic process, however, the underlying mechanisms involved have only been partially disentangled. We examined the effect of intraspecific competition on corticosterone levels during larval development of the toad Rhinella arenarum and its ultimate effects on cell proliferation in particular brain areas as well as the pituitary gland. While overcrowding altered the number of proliferating cells in the pituitary gland, hypothalamus, and third ventricle of the brain, no differences were observed in areas which are less associated with neuroendocrine processes, such as the first ventricle of the brain. Apoptosis was increased in hypothalamic regions but not in the pituitary. With regards to pituitary cell populations, thyrotrophs but not somatoatrophs and corticotrophs showed a decrease in the cell number in overcrowded larvae. Our study shows that alterations in growth and development, produced by stress, results from an imbalance in the neuroendocrine systems implicated in orchestrating the timing of metamorphosis. J. Exp. Zool. 9999A:XX-XX, 2016. © 2016 Wiley Periodicals, Inc. PMID:26817921

  7. Patterns of Cranial Development in Larval Rana macrocnemis: Chondrocranial Size and Shape Relationship With Pelophylax bedriagae (Anura: Ranidae).

    PubMed

    Yildirim, Elıf; Kaya, Uğur

    2016-06-01

    Notwithstanding the abundance of amphibians, there are few descriptions about ranid cranial development. Herein, larval chondrocranial development of Uludağ frog, Rana macrocnemis (Boulenger, 1885), is described on cleared and double-stained specimens. Descriptions are related with the ontogeny of the chondrocranium and osteogenesis of the cranial skeleton. The larval chondrocranial development of R. macrocnemis is compared to those of Rana and Pelophylax larvae (Pelophylax bedriagae, Rana pipiens, R. palustris, R. sphenocephala, R. catesbeiana, R. clamitans and R. sylvatica). In R. macrocnemis, the first bones to ossify are the parasphenoid and exoccipital (Stage 33), followed by the frontoparietal and prootic (stages 35 and 40, respectively). The major reconstruction of the chondrocranium begins at Stage 41. The ossification sequence of R. macrocnemis is distinguished from other ranids. Adult cranial osteology of R. macrocnemis is compared to that of P. bedriagae. Osteologically, R. macrocnemis is different from P. bedriagae by the shape and size of the vomer and number of teeth. Additionally, geometric morphometric methods are used to analyze chondrocranial size and shape changes of ranid larva of R. macrocnemis and P. bedriagae. Anat Rec, 299:711-721, 2016. © 2016 Wiley Periodicals, Inc. PMID:26950267

  8. Chronic effects of strobilurin fungicides on development, growth, and mortality of larval Great Plains toads (Bufo cognatus).

    PubMed

    Hartman, Emily A H; Belden, Jason B; Smith, Loren M; McMurry, Scott T

    2014-04-01

    Agricultural fungicide application has increased tenfold since 2005 in the United States. Active ingredients and formulations of strobilurin fungicides at environmentally relevant concentrations cause mortality to larval and metamorph amphibians; however, little is known about chronic exposure effects in amphibians. We exposed larval amphibians (Bufo cognatus) throughout metamorphosis to the common fungicide formulations Headline(®), Stratego(®), Quilt(®), and a control to determine effects on development and growth. Formulations were tested at 1.7, 50, and 400 μg/L of the active strobilurin ingredient for Headline(®), Stratego(®), and Quilt(®), respectively. Fungicide exposure did not affect body mass or snout-vent length at metamorphosis. However, exposure to Headline(®) at 1.7 μg/L increased the development rate of tadpoles by approximately 5 days compared to the control, an effect not observed for Stratego(®) and Quilt(®). Stratego(®) also caused approximately 35 % cumulative mortality. Results from the experiment suggest that chronic effects of strobilurin fungicides on development, growth, and mortality to B. cognatus are apparent at environmentally relevant concentrations. PMID:24522617

  9. Combined effects of pollutants and salinity on embryo-larval development of the Pacific oyster, Crassostrea gigas.

    PubMed

    Gamain, Perrine; Gonzalez, Patrice; Cachot, Jérôme; Pardon, Patrick; Tapie, Nathalie; Gourves, Pierre Yves; Budzinski, Hélène; Morin, Bénédicte

    2016-02-01

    For several years, low larval recruitment has been observed in Arcachon Bay, in southwest France. Exposure to pollutants could partly account for the reduction of early life stages of the Pacific oyster. This study evaluated the effects of copper and S-metolachlor in combination with salinity on the early life stages of Crassostrea gigas. Embryos were exposed to concentrations of copper (1, 10 and 50 μg L(-1)) or S-metolachlor (10, 100 and 1000 ng L(-1)) and six salinities (18, 21, 24, 27, 30 and 33 u.s.i). Embryotoxicity was measured by considering both the percentage of abnormalities and arrested development in D-shaped larvae. Embryo-larval development was only affected at salinities ≤24 u.s.i, which have never been observed during C. gigas reproduction period in Arcachon Bay. Both contaminants had an effect at environmental concentrations. Our results suggest that copper and metolachlor toxicity was enhanced with decreasing salinity. PMID:26583531

  10. The effects of the amphibian chytrid fungus, insecticide exposure, and temperature on larval anuran development and survival.

    PubMed

    Rumschlag, Samantha L; Boone, Michelle D; Fellers, Gary

    2014-11-01

    Chytridiomycosis, a disease caused by Batrachochytrium dendrobatidis (Bd), has been implicated as a cause of amphibian declines. Susceptibility may be influenced by environmental factors that suppress the immune response. The authors conducted a laboratory study to examine the effect of temperature, insecticide exposure, and Bd exposure during larval anuran development. The authors examined the consequences of exposure to Bd, an insecticide (carbaryl or malathion), and static or fluctuating temperature (15 °C, 20 °C, 25 °C, or 15 °C to 25 °C 72-h flux) on larval development through metamorphosis of the Pacific treefrog (Pseudacris regilla). High and fluctuating temperature had negative effects on survival in the presence of Bd. Insecticides inhibited the effects of Bd; time to tail resorption of Pacific treefrogs decreased when tadpoles were exposed to carbaryl. The present study indicates that abiotic factors may play a role in the host-pathogen interactions in this system. PMID:25098758

  11. Larval development of the Chinese mitten crab Eriocheir sinensis H. Milne-Edwards (Decapoda: Grapsidae) reared in the laboratory

    NASA Astrophysics Data System (ADS)

    Montú, M.; Anger, K.; de Bakker, C.

    1996-06-01

    Larvae of the Chinese mitten crab Eriocheir sinensis were reared in the laboratory from the time of hatching and through metamorphosis. Development normally consists of a Prezoea, 5 Zoea stages, and a Megalopa. Occasionally, an additional (stage VI) Zoea and, in one case, an additional Megalopa (transitional to the first crab stage) were observed. Detailed morphological descriptions of all larval and the first two juvenile instars are given, and larval morphology is compared with that of two closely related species, Eriocheir japonicus and Eriocheir rectus, descriptions of which have recently become available. The zoeal stages of these species can be distinguished by their different number of aesthetascs and setae on the antennules, and different setation of maxillipeds 1 and 2. The Megalopa shows differences in the shape of the rostrum and again in the morphology of the antennule. These and other morphological differences (mainly in setation and spinulation of the zoeal carapace) between E. sinensis and E. japonicus larvae suggest that they may be very closely related but separate species; this contradicts a recent study of adult morphometrics and molecular genetics (Li et al., 1993), suggesting that they are only varieties of a single species.

  12. Embryonic, Larval, and Juvenile Development of the Sea Biscuit Clypeaster subdepressus (Echinodermata: Clypeasteroida)

    PubMed Central

    Vellutini, Bruno C.; Migotto, Alvaro E.

    2010-01-01

    Sea biscuits and sand dollars diverged from other irregular echinoids approximately 55 million years ago and rapidly dispersed to oceans worldwide. A series of morphological changes were associated with the occupation of sand beds such as flattening of the body, shortening of primary spines, multiplication of podia, and retention of the lantern of Aristotle into adulthood. To investigate the developmental basis of such morphological changes we documented the ontogeny of Clypeaster subdepressus. We obtained gametes from adult specimens by KCl injection and raised the embryos at 26C. Ciliated blastulae hatched 7.5 h after sperm entry. During gastrulation the archenteron elongated continuously while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larvae began to feed in 3 d and were 20 d old at metamorphosis; starved larvae died 17 d after fertilization. Postlarval juveniles had neither mouth nor anus nor plates on the aboral side, except for the remnants of larval spicules, but their bilateral symmetry became evident after the resorption of larval tissues. Ossicles of the lantern were present and organized in 5 groups. Each group had 1 tooth, 2 demipyramids, and 2 epiphyses with a rotula in between. Early appendages consisted of 15 spines, 15 podia (2 types), and 5 sphaeridia. Podial types were distributed in accordance to Lovén's rule and the first podium of each ambulacrum was not encircled by the skeleton. Seven days after metamorphosis juveniles began to feed by rasping sand grains with the lantern. Juveniles survived in laboratory cultures for 9 months and died with wide, a single open sphaeridium per ambulacrum, aboral anus, and no differentiated food grooves or petaloids. Tracking the morphogenesis of early juveniles is a necessary step to elucidate the developmental mechanisms of echinoid growth and important groundwork to clarify homologies between irregular urchins. PMID:20339592

  13. [Embrionary-larval development of the tropical fish Hemirhamphus brasiliensis (Beloniformes: Hemirhamphidae) from eggs collected in the wild].

    PubMed

    Rosas, Jesús; Mata, Ernesto; Velásquez, Aidé; Cabrera, Tomas

    2008-09-01

    The embryo formation and larval development of Hemirhamphus brasiliensis Linnaeus, 1758 (Pisces: Hemirhamphidae) is described from morula stage eggs collected on Sargassum sp. Thalii in the field (10 degrees 50'55.2" N y 64 degrees 09'467" W). The eggs were spherical, 1 923.54 +/- 72.35 microm diameter with several corionic filaments, and are striated. During the first 48 h the embryo developed cephalic vesicle, miomers, and a heart located on the external body surface, beating strongly and circulating colorless blood which became pigmented red later. Before hatching, the larva developed kidney, gut tract, liver and biliar vesicle, pectoral fins, four pairs of gill arches and the mouth. The larva hatched at 114 h, the body was torpedo-shaped, yellow-green, with several dendriform melanophores; the pelvic fin was observed 72 h post hatching. At 240 hours the metamorphoses was completed. When the larvae hatched they could ingest Artemia metanauplii. PMID:19419056

  14. Isolation of intact larval haemoglobin from the brine shrimp Artemia salina. Prevention of degradation in vitro by proteases induced during larval development.

    PubMed

    Mansfield, B C; Krissansen, G W; Smith, M G; Tate, W P

    1980-05-29

    Haemoglobin induced in the larval stage of the brine shrimp, Artemia salina is extensively degraded when isolated from the later developmental stages of the larvae. Alkaline proteases appear in the organism a few hours after the induction of haemoglobin and cause the observed degradation. Addition of 2.6 mM phenylmethylsulphonyl fluoride or 20 micrograms/ml soybean trypsin inhibitor to the extraction buffer used for haemoglobin isolation prevents most of this degradation. Discrete haem proteins are found in extracts of the brine shrimp larvae isolated before induction of the proteases, and the major species has a molecular weight of over 200,000. This is believed to be the native haemoglobin. A spread of lower molecular weight haem-containing polypeptides is found in extracts of larvae isolated after induction of the proteases. These products are believed to result from degradation of the discrete haem proteins present in protease-free extracts. PMID:6990994

  15. Chitosan/siRNA nanoparticle targeting demonstrates a requirement for single-minded during larval and pupal olfactory system development of the vector mosquito Aedes aegypti

    PubMed Central

    2014-01-01

    Background Essentially nothing is known about the genetic regulation of olfactory system development in vector mosquitoes, which use olfactory cues to detect blood meal hosts. Studies in Drosophila melanogaster have identified a regulatory matrix of transcription factors that controls pupal/adult odorant receptor (OR) gene expression in olfactory receptor neurons (ORNs). However, it is unclear if transcription factors that function in the D. melanogaster regulatory matrix are required for OR expression in mosquitoes. Furthermore, the regulation of OR expression during development of the larval olfactory system, which is far less complex than that of pupae/adults, is not well understood in any insect, including D. melanogaster. Here, we examine the regulation of OR expression in the developing larval olfactory system of Aedes aegypti, the dengue vector mosquito. Results A. aegypti bears orthologs of eight transcription factors that regulate OR expression in D. melanogaster pupae/adults. These transcription factors are expressed in A. aegypti larval antennal sensory neurons, and consensus binding sites for these transcription factors reside in the 5’ flanking regions of A. aegypti OR genes. Consensus binding sites for Single-minded (Sim) are located adjacent to over half the A. aegypti OR genes, suggesting that this transcription factor functions as a major regulator of mosquito OR expression. To functionally test this hypothesis, chitosan/siRNA nanoparticles were used to target sim during larval olfactory development. These experiments demonstrated that Sim positively regulates expression of a large subset of OR genes, including orco, the obligate co-receptor in the assembly and function of heteromeric OR/Orco complexes. Decreased innervation of the antennal lobe was also noted in sim knockdown larvae. These OR expression and antennal lobe defects correlated with a larval odorant tracking behavioral defect. OR expression and antennal lobe defects were also

  16. Looming detection by identified visual interneurons during larval development of the locust Locusta migratoria.

    PubMed

    Simmons, Peter J; Sztarker, Julieta; Rind, F Claire

    2013-06-15

    Insect larvae clearly react to visual stimuli, but the ability of any visual neuron in a newly hatched insect to respond selectively to particular stimuli has not been directly tested. We characterised a pair of neurons in locust larvae that have been extensively studied in adults, where they are known to respond selectively to objects approaching on a collision course: the lobula giant motion detector (LGMD) and its postsynaptic partner, the descending contralateral motion detector (DCMD). Our physiological recordings of DCMD axon spikes reveal that at the time of hatching, the neurons already respond selectively to objects approaching the locust and they discriminate between stimulus approach speeds with differences in spike frequency. For a particular approaching stimulus, both the number and peak frequency of spikes increase with instar. In contrast, the number of spikes in responses to receding stimuli decreases with instar, so performance in discriminating approaching from receding stimuli improves as the locust goes through successive moults. In all instars, visual movement over one part of the visual field suppresses a response to movement over another part. Electron microscopy demonstrates that the anatomical substrate for the selective response to approaching stimuli is present in all larval instars: small neuronal processes carrying information from the eye make synapses both onto LGMD dendrites and with each other, providing pathways for lateral inhibition that shape selectivity for approaching objects. PMID:23531812

  17. Mitochondrial fusion but not fission regulates larval growth and synaptic development through steroid hormone production

    PubMed Central

    Sandoval, Hector; Yao, Chi-Kuang; Chen, Kuchuan; Jaiswal, Manish; Donti, Taraka; Lin, Yong Qi; Bayat, Vafa; Xiong, Bo; Zhang, Ke; David, Gabriela; Charng, Wu-Lin; Yamamoto, Shinya; Duraine, Lita; Graham, Brett H; Bellen, Hugo J

    2014-01-01

    Mitochondrial fusion and fission affect the distribution and quality control of mitochondria. We show that Marf (Mitochondrial associated regulatory factor), is required for mitochondrial fusion and transport in long axons. Moreover, loss of Marf leads to a severe depletion of mitochondria in neuromuscular junctions (NMJs). Marf mutants also fail to maintain proper synaptic transmission at NMJs upon repetitive stimulation, similar to Drp1 fission mutants. However, unlike Drp1, loss of Marf leads to NMJ morphology defects and extended larval lifespan. Marf is required to form contacts between the endoplasmic reticulum and/or lipid droplets (LDs) and for proper storage of cholesterol and ecdysone synthesis in ring glands. Interestingly, human Mitofusin-2 rescues the loss of LD but both Mitofusin-1 and Mitofusin-2 are required for steroid-hormone synthesis. Our data show that Marf and Mitofusins share an evolutionarily conserved role in mitochondrial transport, cholesterol ester storage and steroid-hormone synthesis. DOI: http://dx.doi.org/10.7554/eLife.03558.001 PMID:25313867

  18. Post-embryonic larval development and metamorphosis of the hydroid Eudendrium racemosum (Cavolini) (Hydrozoa, Cnidaria)

    NASA Astrophysics Data System (ADS)

    Sommer, C.

    1990-09-01

    The morphology and histology of the planula larva of Eudendrium racemosum (Cavolini) and its metamorphosis into the primary polyp are described from light microscopic observations. The planula hatches as a differentiated gastrula. During the lecithotrophic larval period, large ectodermal mucous cells, embedded between epitheliomuscular cells, secrete a sticky slime. Two granulated cell types occur in the ectoderm that are interpreted as secretory and sensorynervous cells, but might also be representatives of only one cell type with a multiple function. The entoderm consists of yolk-storing gastrodermal cells, digestive gland cells, interstitial cells, cnidoblasts, and premature cnidocytes. The larva starts metamorphosis by affixing its blunt aboral pole to a substratum. While the planula flattens down, the mucous cells penetrate the mesolamella and migrate through the entoderm into the gastral cavity where they are lysed. Subsequently, interstitial cells, cnidoblasts, and premature cnidocytes migrate in the opposite direction, i.e. from entoderm to ectoderm. Then, the polypoid body organization, comprising head (hydranth), stem and foot, all covered by peridermal secretion, becomes recognisable. An oral constriction divides the hypostomal portion of the gastral cavity from the stomachic portion. Within the hypostomal entoderm, cells containing secretory granules differentiate. Following growth and the multiplication of tentacles, the head periderm disappears. A ring of gland cells differentiates at the hydranth's base. The positioning of cnidae in the tentacle ectoderm, penetration of the mouth opening and the multiplication of digestive gland cells enable the polyp to change from lecithotrophic to planktotrophic nutrition.

  19. Drosophila cortex and neuropile glia influence secondary axon tract growth, pathfinding, and fasciculation in the developing larval brain.

    PubMed

    Spindler, Shana R; Ortiz, Irma; Fung, Siaumin; Takashima, Shigeo; Hartenstein, Volker

    2009-10-15

    Glial cells play important roles in the developing brain during axon fasciculation, growth cone guidance, and neuron survival. In the Drosophila brain, three main classes of glia have been identified including surface, cortex, and neuropile glia. While surface glia ensheaths the brain and is involved in the formation of the blood-brain-barrier and the control of neuroblast proliferation, the range of functions for cortex and neuropile glia is less well understood. In this study, we use the nirvana2-GAL4 driver to visualize the association of cortex and neuropile glia with axon tracts formed by different brain lineages and selectively eliminate these glial populations via induced apoptosis. The larval central brain consists of approximately 100 lineages. Each lineage forms a cohesive axon bundle, the secondary axon tract (SAT). While entering and traversing the brain neuropile, SATs interact in a characteristic way with glial cells. Some SATs are completely invested with glial processes; others show no particular association with glia, and most fall somewhere in between these extremes. Our results demonstrate that the elimination of glia results in abnormalities in SAT fasciculation and trajectory. The most prevalent phenotype is truncation or misguidance of axon tracts, or abnormal fasciculation of tracts that normally form separate pathways. Importantly, the degree of glial association with a given lineage is positively correlated with the severity of the phenotype resulting from glial ablation. Previous studies have focused on the embryonic nerve cord or adult-specific compartments to establish the role of glia. Our study provides, for the first time, an analysis of glial function in the brain during axon formation and growth in larval development. PMID:19646433

  20. Drosophila cortex and neuropile glia influence secondary axon tract growth, pathfinding, and fasciculation in the developing larval brain

    PubMed Central

    Spindler, Shana R; Ortiz, Irma; Fung, Siaumin; Takashima, Shigeo; Hartenstein, Volker

    2009-01-01

    Glial cells play important roles in the developing brain during axon fasciculation, growth cone guidance, and neuron survival. In the Drosophila brain, three main classes of glia have been identified including surface, cortex, and neuropile glia. While surface glia ensheaths the brain and is involved in the formation of the blood-brain-barrier and the control of neuroblast proliferation, the range of functions for cortex and neuropile glia is less well understood. In this study, we use the nirvana2-GAL4 driver to visualize the association of cortex and neuropile glia with axon tracts formed by different brain lineages and selectively eliminate these glial populations via induced apoptosis. The larval central brain consists of approximately 100 lineages. Each lineage forms a cohesive axon bundle, the secondary axon tract (SAT). While entering and traversing the brain neuropile, SATs interact in a characteristic way with glial cells. Some SATs are completely invested with glial processes; others show no particular association with glia, and most fall somewhere in between these extremes. Our results demonstrate that the elimination of glia results in abnormalities in SAT fasciculation and trajectory. The most prevalent phenotype is truncation or misguidance of axon tracts, or abnormal fasciculation of tracts that normally form separate pathways. Importantly, the degree of glial association with a given lineage is positively correlated with the severity of the phenotype resulting from glial ablation. Previous studies have focused on the embryonic nerve cord or adult specific compartments to establish the role of glia. Our study provides, for the first time, an analysis of glial function in the brain during axon formation and growth in larval development. PMID:19646433

  1. She’s a femme fatale: low-density larval development produces good disease vectors

    PubMed Central

    Juliano, Steven A; Ribeiro, Gabriel Sylvestre; Maciel-de-Freitas, Rafael; Castro, Márcia G; Codeço, Claudia; Lourenço-de-Oliveira, Ricardo; Lounibos, L Philip

    2014-01-01

    Two hypotheses for how conditions for larval mosquitoes affect vectorial capacity make opposite predictions about the relationship of adult size and frequency of infection with vector-borne pathogens. Competition among larvae produces small adult females. The competition-susceptibility hypothesis postulates that small females are more susceptible to infection and predicts frequency of infection should decrease with size. The competition-longevity hypothesis postulates that small females have lower longevity and lower probability of becoming competent to transmit the pathogen and thus predicts frequency of infection should increase with size. We tested these hypotheses for Aedes aegypti in Rio de Janeiro, Brazil, during a dengue outbreak. In the laboratory, longevity increases with size, then decreases at the largest sizes. For field-collected females, generalised linear mixed model comparisons showed that a model with a linear increase of frequency of dengue with size produced the best Akaike’s information criterion with a correction for small sample sizes (AICc). Consensus prediction of three competing models indicated that frequency of infection increases monotonically with female size, consistent with the competition-longevity hypothesis. Site frequency of infection was not significantly related to site mean size of females. Thus, our data indicate that uncrowded, low competition conditions for larvae produce the females that are most likely to be important vectors of dengue. More generally, ecological conditions, particularly crowding and intraspecific competition among larvae, are likely to affect vector-borne pathogen transmission in nature, in this case via effects on longevity of resulting adults. Heterogeneity among individual vectors in likelihood of infection is a generally important outcome of ecological conditions impacting vectors as larvae. PMID:25591112

  2. Involvement of a putative allatostatin in regulation of juvenile hormone titer and the larval development in Leptinotarsa decemlineata (Say).

    PubMed

    Meng, Qing-Wei; Liu, Xin-Ping; Lü, Feng-Gong; Fu, Kai-Yun; Guo, Wen-Chao; Li, Guo-Qing

    2015-01-01

    Juvenile hormone III (JH III) plays primary roles in regulation of metamorphosis, reproduction and diapause in Leptinotarsa decemlineata, a notorious defoliator of potato. The neurosecretory cell-borne substance(s) negatively affects the final two steps in JH biosynthesis, catalyzed respectively by an epoxidase CYP15A1 and a juvenile hormone acid methyltransferase (JHAMT). In a few insect species other than L. decemlineata, the inhibitory substance is allatostatin (AS) neuropeptide. In this study, two putative AS genes encoding LdAS-C and LdAS-B precursors were cloned. Both LdAS-C and LdAS-B were expressed in the egg, larvae, pupae and adults, and highly expressed in the brain and the gut. Dietary introduction of double-stranded RNAs (dsRNAs) targeting LdAS-C and LdAS-B successfully knocked down respective target genes. Ingestion during 3 and 6 consecutive days of dsLdAS-C significantly increased the LdJHAMT mRNA levels by 3.8 and 9.9 fold respectively. In contrast, ingestion of dsLdAS-B only slightly increased the LdJHAMT expression level by 1.1 and 1.7 fold. Moreover, after one, two and three days' ingestion of dsLdAS-C, the relative JH levels in the hemolymph of treated larvae were 2.5, 4.2 and 1.9 fold higher than those in control beetles. Furthermore, ingestion of dsLdAS-C and dsLdAS-B significantly affected larval growth and delayed larval development. Thus, we provide a line of experimental evidence in L. decemlineata to support the concept that AS-C acts as an allatostatin and inhibit JH biosynthesis. PMID:25452193

  3. The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve

    NASA Astrophysics Data System (ADS)

    Li, Jiaqi; Jiang, Zengjie; Zhang, Jihong; Mao, Yuze; Bian, Dapeng; Fang, Jianguang

    2014-11-01

    We evaluated the effect of pH on larval development in larval Pacific oyster ( Crassostrea gigas) and blood cockle ( Arca inflata Reeve). The larvae were reared at pH 8.2 (control), 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.

  4. Development of liquid larval diet with modified rearing system for Bactrocera dorsalis (Hendel) (Diptera:Tephritidae) for the application of sterile insect technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A liquid larval diet and its rearing system have been developed for mass rearing of Bactrocera dorsalis (Hendel) in Hawaii. Rearing facility in Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Dhaka, Bangladesh, modified protein source from brewer's yeast to a combinat...

  5. GROWTH AND VARIATIONS IN LIPID CLASS AND FATTY ACID COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986

    EPA Science Inventory

    Larval development in decapod crustaceans is marked by variable growth patterns and changes in weight and biochemical composition. Larvae of the stone crab, Menippe adina, were mass-reared under laboratory conditions (28|C; 20o/ooS) from hatching to the megalopal stage. Growth in...

  6. EFFECTS OF SOLUBLE FRACTIONS OF USED LIGHT-WEIGHT LIGNOSULFONATE TYPE MUD AND HEXAVALENT CHROMIUM ON THE COMPLETE LARVAL DEVELOPMENT OF THE CRABS, 'RHITHROPANOPEUS HARRISII' AND 'CALLINECTES SAPIDUS'

    EPA Science Inventory

    The mud aqueous fractions (MAF) and suspended particulate phase (SPP) of lignosulfonate type mud were nontoxic to the complete larval development of Rhithropanopeus harrisii. Five percent MAF and SPP were not toxic to Callinectes sapidus. Differential survival of C. sapidus larva...

  7. Complete larval development of Thor amboinensis (De Man, 1888) Decapoda: Thoridae) described from laboratory-reared material
    and identified by DNA barcoding.

    PubMed

    Bartilotti, Cátia; Salabert, Joana; Santos, Antonina Dos

    2016-01-01

    Of the 12 species of Thor described until present date, only three (25%) have their complete larval development known. Present work describes the complete larval development of Thor amboinensis, based on laboratory-reared material. The spent females were identified through the analysis of the partial sequences of the mitochondrial DNA barcode, also used for the reconstruction of the phylogenetic relationships within the recently resurrected and recognized family Thoridae Kingsley, 1879. Eight zoeal stages and one decapodid complete this species larval development. In the genus Thor, the number of zoeal stages varies greatly from two (T. dobkini) to eight (T. amboinensis and T. floridanus). The larvae of T. ambionensis and T. floridanus are readily distinguished from each other by the ornamentation of the ventral margin of the carapace and the pereiopods development. The first zoeal stage of T. amboinensis described by Yang & Okuno (2004) and the one described in present study are very similar. A brief discussion on the morphological characters and on the number of zoeal stages of the genus, as well as of the previous larval descriptions is made. The phylogenetic analysis suggest cryptic speciation for geographical separated populations of T. amboinensis, paraphyly of the genus Eualus, and the reassignment of E. cranchii to a different genus. PMID:27395843

  8. GROWTH AND VARIATIONS IN LIPID CLASS AND FATTY ACID COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986.

    EPA Science Inventory

    Larval development in decapod crustaceans is marked by variable growth patterns and changes in weight and biochemical composition. Larvae of the stone crab, Menippe adina, were mass-reared under laboratory conditions (28?C; 20o/ooS) from hatching to the megalopa stage. Growth in...

  9. Abbreviation of larval development and extension of brood care as key features of the evolution of freshwater Decapoda.

    PubMed

    Vogt, Günter

    2013-02-01

    The transition from marine to freshwater habitats is one of the major steps in the evolution of life. In the decapod crustaceans, four groups have colonized fresh water at different geological times since the Triassic, the freshwater shrimps, freshwater crayfish, freshwater crabs and freshwater anomurans. Some families have even colonized terrestrial habitats via the freshwater route or directly via the sea shore. Since none of these taxa has ever reinvaded its environment of origin the Decapoda appear particularly suitable to investigate life-history adaptations to fresh water. Evolutionary comparison of marine, freshwater and terrestrial decapods suggests that the reduction of egg number, abbreviation of larval development, extension of brood care and lecithotrophy of the first posthatching life stages are key adaptations to fresh water. Marine decapods usually have high numbers of small eggs and develop through a prolonged planktonic larval cycle, whereas the production of small numbers of large eggs, direct development and extended brood care until the juvenile stage is the rule in freshwater crayfish, primary freshwater crabs and aeglid anomurans. The amphidromous freshwater shrimp and freshwater crab species and all terrestrial decapods that invaded land via the sea shore have retained ocean-type planktonic development. Abbreviation of larval development and extension of brood care are interpreted as adaptations to the particularly strong variations of hydrodynamic parameters, physico-chemical factors and phytoplankton availability in freshwater habitats. These life-history changes increase fitness of the offspring and are obviously favoured by natural selection, explaining their multiple origins in fresh water. There is no evidence for their early evolution in the marine ancestors of the extant freshwater groups and a preadaptive role for the conquest of fresh water. The costs of the shift from relative r- to K-strategy in freshwater decapods are traded

  10. Transcriptomic Analysis of Differentially Expressed Genes During Larval Development of Rapana venosa by Digital Gene Expression Profiling

    PubMed Central

    Song, Hao; Yu, Zheng-Lin; Sun, Li-Na; Xue, Dong-Xiu; Zhang, Tao; Wang, Hai-Yan

    2016-01-01

    During the life cycle of shellfish, larval development, especially metamorphosis, has a vital influence on the dynamics, distribution, and recruitment of natural populations, as well as seed breeding. Rapana venosa, a carnivorous gastropod, is an important commercial shellfish in China, and is an ecological invader in the United States, Argentina, and France. However, information about the mechanism of its early development is still limited, because research in this area has long suffered from a lack of genomic resources. In this study, 15 digital gene expression (DGE) libraries from five developmental stages of R. venosa were constructed and sequenced on the IIIumina Hi-Sequation 2500 platform. Bioinformaticsanalysis identified numerous differentially and specifically expressed genes, which revealed that genes associated with growth, nervous system, digestive system, immune system, and apoptosis participate in important developmental processes. The functional analysis of differentially expressed genes was further implemented by gene ontology, and Kyoto encyclopedia of genes and genomes enrichment. DGE profiling provided a general picture of the transcriptomic activities during the early development of R. venosa, which may provide interesting hints for further study. Our data represent the first comparative transcriptomic information available for the early development of R. venosa, which is a prerequisite for a better understanding of the physiological traits controlling development. PMID:27194808

  11. Transcriptomic Analysis of Differentially Expressed Genes During Larval Development of Rapana venosa by Digital Gene Expression Profiling.

    PubMed

    Song, Hao; Yu, Zheng-Lin; Sun, Li-Na; Xue, Dong-Xiu; Zhang, Tao; Wang, Hai-Yan

    2016-01-01

    During the life cycle of shellfish, larval development, especially metamorphosis, has a vital influence on the dynamics, distribution, and recruitment of natural populations, as well as seed breeding. Rapana venosa, a carnivorous gastropod, is an important commercial shellfish in China, and is an ecological invader in the United States, Argentina, and France. However, information about the mechanism of its early development is still limited, because research in this area has long suffered from a lack of genomic resources. In this study, 15 digital gene expression (DGE) libraries from five developmental stages of R. venosa were constructed and sequenced on the IIIumina Hi-Sequation 2500 platform. Bioinformaticsanalysis identified numerous differentially and specifically expressed genes, which revealed that genes associated with growth, nervous system, digestive system, immune system, and apoptosis participate in important developmental processes. The functional analysis of differentially expressed genes was further implemented by gene ontology, and Kyoto encyclopedia of genes and genomes enrichment. DGE profiling provided a general picture of the transcriptomic activities during the early development of R. venosa, which may provide interesting hints for further study. Our data represent the first comparative transcriptomic information available for the early development of R. venosa, which is a prerequisite for a better understanding of the physiological traits controlling development. PMID:27194808

  12. Same but different: Larval development and gall-inducing process of a non-pollinating fig wasp compared to that of pollinating fig-wasps

    NASA Astrophysics Data System (ADS)

    Jansen-González, Sergio; Teixeira, Simone de Padua; Kjellberg, Finn; Pereira, Rodrigo A. Santinelo

    2014-05-01

    The receptacles of fig trees (Ficus spp.) can harbor a highly diversified and complex community of chalcid wasps. Functional groups of fig wasps (e.g. gallers, cleptoparasites and parasitoids) oviposit into the fig at different developmental stages, reflecting different feeding regimes for these insect larvae. There are few direct data available on larval feeding regimes and access to resources. We studied the gall induction and larval feeding strategy of an Idarnes (group flavicollis) species, a non-pollinating fig wasp (NPFW) associated to Ficus citrifolia P. Miller in Brazil. This Idarnes species shares with the pollinator characteristics such as time of oviposition, ovipositor insertion through flower and location of the egg inside plant ovaries. Nevertheless, we show that the gall induction differs considerably from that of the pollinating species. This Idarnes species relies on the induction of nucellus cell proliferation for gall formation and as the main larval resource. This strategy enables it to develop in both pollinated and unpollinated figs. The large differences between this NPFW and other fig wasps in how ovules are galled suggest that there are different ways to be a galler. A functional analysis of NPFW community structure may require descriptions of the histological processes associated with larval development.

  13. Effects of temperature and salinity on larval survival and development in the invasive shrimp Palaemon macrodactylus (Caridea: Palaemonidae) along the reproductive season

    NASA Astrophysics Data System (ADS)

    Guadalupe Vázquez, M.; Bas, Claudia C.; Kittlein, Marcelo; Spivak, Eduardo D.

    2015-05-01

    The invasive shrimp Palaemon macrodactylus is associated mainly with brackish waters. Previous studies raised the question if tolerance to low salinities differs between larvae and adults. To answer this question, the combined effects of two temperatures (20 and 25 °C) and four salinities (5, 12, 23 and 34 psu) on survival and development of larvae that hatched at the beginning, in the midpoint and near the end of a reproductive season (denoted early, middle season and late larvae respectively) were examined. The three types of larvae were able to survive and reach juvenile phase at salinities between 12 and 34 psu and at both temperatures. At 5 psu all larvae died, but 45% molted at least once. Temperature and salinity to a lesser extent, had effects on the duration of development and on the number of larval stages in all larval types. Development was longer at the lower temperature, especially in middle season and late larvae. Most early larvae reached the juvenile phase through 5 larval stages; the number of larval stages of middle season and late larvae was higher at 20 °C and in late larvae also low salinity produced extra stages. Low salinity (12 psu) and, in early and middle season larvae, low temperature produced lighter and smaller individuals. Response of larvae to environmental factors seems to be related in part to the previous conditions (maternal effects and/or embryo development conditions). The narrower salinity tolerance of larvae compared to adults and the ability of zoea I to survive at least some days at 5 psu may be related with an export larval strategy.

  14. VARIATION IN GROWTH, LIPID CLASS AND FATTY ACID COMPOSITION OF THE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) DURING LARVAL DEVELOPMENT FOLLOWING EXPOSURE TO AN INSECT JUVENILE HORMONE ANALOG (FENOXYCARB(R))

    EPA Science Inventory

    This study examines the effects of fenoxycarb?, an insect juvenile hormone (JH) analog, on larval growth, and lipid class and fatty acid composition in first crabs of the mud crab Rhithropanopeus harrisii reared through total larval development in nominal water concentrations fr...

  15. ParaHox gene expression in larval and postlarval development of the polychaete Nereis virens (Annelida, Lophotrochozoa)

    PubMed Central

    Kulakova, Milana A; Cook, Charles E; Andreeva, Tatiana F

    2008-01-01

    Background Transcription factors that encode ANTP-class homeobox genes play crucial roles in determining the body plan organization and specification of different organs and tissues in bilaterian animals. The three-gene ParaHox family descends from an ancestral gene cluster that existed before the evolution of the Bilateria. All three ParaHox genes are reported from deuterostomes and lophotrochozoans, but not to date from any ecdysozoan taxa, and there is evidence that the ParaHox genes, like the related Hox genes, were ancestrally a single chromosomal cluster. However, unlike the Hox genes, there is as yet no strong evidence that the ParaHox genes are expressed in spatial and temporal order during embryogenesis. Results We isolated fragments of the three Nereis virens ParaHox genes, then used these as probes for whole-mount in situ hybridization in larval and postlarval worms. In Nereis virens the ParaHox genes participate in antero-posterior patterning of ectodermal and endodermal regions of the digestive tract and are expressed in some cells in the segment ganglia. The expression of these genes occurs in larval development in accordance with the position of these cells along the main body axis and in postlarval development in accordance with the position of cells in ganglia along the antero-posterior axis of each segment. In none of these tissues does expression of the three ParaHox genes follow the rule of temporal collinearity. Conclusion In Nereis virens the ParaHox genes are expressed during antero-posterior patterning of the digestive system (ectodermal foregut and hindgut, and endodermal midgut) of Nereis virens. These genes are also expressed during axial specification of ventral neuroectodermal cell domains, where the expression domains of each gene are re-iterated in each neuromere except for the first parapodial segment. These expression domains are probably predetermined and may be directed on the antero-posterior axis by the Hox genes, whose

  16. Effect of flavan-3-ols on in vitro egg hatching, larval development and viability of infective larvae of Trichostrongylus colubriformis.

    PubMed

    Molan, A L; Meagher, L P; Spencer, P A; Sivakumaran, S

    2003-12-01

    The effects of flavan-3-ols (the monomer units of condensed tannins (CT)) and their galloyl derivatives on the viability of eggs, the development of first stage (L1) larvae, and the viability of the infective larvae of Trichostrongylus colubriformis were investigated under in vitro conditions. Each of the flavan-3-ol gallates showed some inhibition of egg hatching at 100 microg/ml, and 100% inhibition at 1000 microg/ml, with epigallocatechin gallate being the most effective in the egg hatch (EH) assay. In contrast, none of the flavan-3-ols were able to completely inhibit egg hatching. The flavan-3-ols and galloyl derivatives dose-dependently inhibited the development of infective larvae as assessed by the larval development (LD) assay. A larval migration inhibition (LMI) assay was used to assess the effect of flavan-3-ols and their galloyl derivatives on the motility of the infective third-stage (L3) larvae of T. colubriformis. In general, the flavan-3-ol gallates were more effective than the flavan-3-ols at immobilising the infective larvae as evidenced by their ability to inhibit more (P<0.05-0.01) larvae from passing through the LMI sieves. At 500 microg/ml, epigallocatechin gallate inhibited significantly more (P<0.1) larvae from passing through the sieves than did catechin gallate, epicatechin gallate, or gallocatechin gallate. Comparisons were made between the flavan-3-ols and their galloyl derivatives with the in vitro effects of CT extracts from several forage legumes, which have exhibited effects on parasites in vivo. The forage legumes tested at 200-500 microg/ml reduced the proportion of eggs that hatch, with comparable results to those obtained using the flavan-3-ols. The activities may be influenced by the prodelphinidin: procyanidin (PD:PC) ratios: CT extracts from Lotus pendunculatus and sainfoin have PD:PC ratios of 70:30 and 77:23, respectively, whereas the less active CT extract from Lotus corniculatus has a PD:PC ratio of 27:73. The active CT

  17. In vitro development of Strongylus edentatus to the fourth larval stage with notes on Strongylus vulgaris and Strongylus equinus.

    PubMed

    Farrar, R G; Klei, T R

    1985-08-01

    Strongylus edentatus was successfully cultured in vitro to the fourth larval stage (L4). Some growth continued for periods of 40-50 days at which time reductions in viability were observed in some of the culture systems tested. Various combinations of media, sera, buffers and organ explant cultures were tested. All cultures were incubated at 37 C in an atmosphere of 95% air and 5% CO2. Larvae underwent growth and differentiation to the L4 in all medium-serum combinations with and without organ explant cultures. Development and growth did occur but viability was reduced to insignificant levels in media without serum or cells. Optimal growth, differentiation, and longevity were observed in bicarbonate buffered RPMI-1640 containing 10% fetal calf serum and gerbil (Meriones unguiculatus) cecum explant cultures. Observations indicated that Strongylus vulgaris and Strongylus equinus also developed to the L4 stage using similar techniques. However, viability of S. vulgaris L4 was markedly limited. Specific morphological changes marked phases of development of S. edentatus, categorized as early, middle and late third stage, third molt and early fourth stage. Strongylus equinus appeared to follow the same developmental pattern in vitro as S. edentatus. Distinct differences in morphological features during differentiation were observed between S. edentatus and S. vulgaris. PMID:4032151

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

    NASA Technical Reports Server (NTRS)

    Steyger, P. S.; Wiederhold, M. L.; Batten, J.

    1995-01-01

    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.

  19. Heterochrony in mandible development of larval shrimp (Decapoda: Caridea)--a comparative morphological SEM study of two carideans.

    PubMed

    Batel, Annika; Melzer, Roland R; Anger, Klaus; Geiselbrecht, Hannes

    2014-11-01

    Mandible development in the larval stages I-V of two palaemonid shrimp species, Palaemon elegans and Macrobrachium amazonicum, was analyzed using scanning electron microscopy, light microscopy, and confocal laser scanning microscopy. In contrast to the zoea I of P. elegans, first-stage larvae of M. amazonicum are nonfeeding. At hatching, the morphology of the mandibles is fully expressed in P. elegans, while it appears underdeveloped in M. amazonicum, presenting only small precursors of typical caridean features. In successive zoeal stages, both species show similar developmental changes, but the mandibular characters of the larvae in M. amazonicum were delayed compared to the equivalent stages in P. elegans, especially in the development of submarginal setae and mandible size. In conclusion, our results indicate heterochrony (postdisplacement) of mandible development in M. amazonicum compared to that in P. elegans, which is related to initial lack of mandible functionality or planktivorous feeding at hatching, respectively. This conclusion is supported by comparison with other palaemonid zoeae exhibiting different feeding modes. Our data suggest that an evolutionary ground pattern of mandible morphology is present even in species with nonfeeding first-stage larvae. PMID:24888760

  20. Eukaryotic translation initiation factor 5B activity regulates larval growth rate and germline development in Caenorhabditis elegans.

    PubMed

    Yu, Xiang; Vought, Valarie E; Conradt, Barbara; Maine, Eleanor M

    2006-09-01

    In C. elegans, a population of proliferating germ cells is maintained via GLP-1/Notch signaling; in the absence of GLP-1 signaling, germ cells prematurely enter meiosis and differentiate. We previously identified ego (enhancer of glp-1) genes that promote germline proliferation and interact genetically with the GLP-1 signaling pathway. Here, we report that iffb-1 (initiation factor five B) is an ego gene. iffb-1 encodes the sole C. elegans isoform of eukaryotic translation initiation factor 5B, a protein essential for translation. We have used RNA interference and a deletion mutation to determine the developmental consequences of reduced iffb-1 activity. Our data indicate that maternal iffb-1 gene expression is sufficient for embryogenesis, and zygotic iffb-1 expression is required for development beyond late L1/early L2 stage. Partial reduction in iffb-1 expression delays larval development and can severely disrupt proliferation and differentiation of germ cells. We hypothesize that germline development is particularly sensitive to iffb-1 expression level. PMID:16937415

  1. Effects of a fungicide formulation on embryo-larval development, metamorphosis, and gonadogenesis of the South American toad Rhinella arenarum.

    PubMed

    Svartz, Gabriela; Meijide, Fernando; Pérez Coll, Cristina

    2016-07-01

    Sublethal toxicity of the formulated fungicide Maxim(®) XL on embryonic, larval and juvenile development of Rhinella arenarum was evaluated by means of standardized bioassays. Maxim(®) XL, one of the most used fungicides in Argentina, is based on a mixture of two active ingredients: Fludioxonil and Metalaxyl-M. Maxim(®) XL exposure induced severe sublethal effects on the embryos, expressed as general underdevelopment, axial flexures, microcephaly, cellular dissociation, abnormal pigmentation, underdeveloped gills, marked edema and wavy tail. As the embryo development advanced, alterations in behavior as spasmodic contractions, general weakness and inanition were observed. Maxim(®) XL did not affect neither the time required to complete metamorphosis nor sex proportions, but gonadal development and differentiation were impaired. Gross gonadal analysis revealed a significant proportion of exposed individuals with underdevelopment of one or both gonads. Histological analysis confirmed that 18% and 10% of the individuals exposed to 0.25 and 2mg/L Maxim(®) XL, respectively, exhibited undifferentiated gonads characterized by a reduced number (or absence) of germ cells. Taking into account the risk evaluation performed by means of Hazard Quotients, this fungicide could be a threat to R. arenarum populations under chronic exposure. This study represents the first evidence of toxic effects exerted by Maxim(®) XL on amphibians. Finally, our findings highlight the properties of this fungicide that might jeopardize non-target living species exposed to it in agricultural environments. PMID:27214195

  2. Transgenerational Effects of Parental Larval Diet on Offspring Development Time, Adult Body Size and Pathogen Resistance in Drosophila melanogaster

    PubMed Central

    Valtonen, Terhi M.; Kangassalo, Katariina; Pölkki, Mari; Rantala, Markus J.

    2012-01-01

    Environmental conditions experienced by parents are increasingly recognized to affect offspring performance. We set out to investigate the effect of parental larval diet on offspring development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. Flies for the parental generation were raised on either poor or standard diet and then mated in the four possible sex-by-parental diet crosses. Females that were raised on poor food produced larger offspring than females that were raised on standard food. Furthermore, male progeny sired by fathers that were raised on poor food were larger than male progeny sired by males raised on standard food. Development times were shortest for offspring whose one parent (mother or the father) was raised on standard and the other parent on poor food and longest for offspring whose parents both were raised on poor food. No evidence for transgenerational effects of parental diet on offspring disease resistance was found. Although paternal effects have been previously demonstrated in D. melanogaster, no earlier studies have investigated male-mediated transgenerational effects of diet in this species. The results highlight the importance of not only considering the relative contribution each parental sex has on progeny performance but also the combined effects that the two sexes may have on offspring performance. PMID:22359607

  3. Effects of juvenile hormone (JH) analog insecticides on larval development and JH esterase activity in two spodopterans.

    PubMed

    El-Sheikh, El-Sayed A; Kamita, Shizuo G; Hammock, Bruce D

    2016-03-01

    Juvenile hormone analog (JHA) insecticides are biological and structural mimics of JH, a key insect developmental hormone. Toxic and anti-developmental effects of the JHA insecticides methoprene, fenoxycarb, and pyriproxyfen were investigated on the larval and pupal stages of Spodoptera littoralis and Spodoptera frugiperda. Bioassays showed that fenoxycarb has the highest toxicity and fastest speed of kill in 2nd instar S. littoralis. All three JHAs affected the development of 6th instar (i.e., final instar) and pupal S. frugiperda. JH esterase (JHE) is a critical enzyme that helps to regulate JH levels during insect development. JHE activity in the last instar S. littoralis and S. frugiperda was 11 and 23 nmol min(-1) ml(-1) hemolymph, respectively. Methoprene and pyriproxyfen showed poor inhibition of JHE activity from these insects, whereas fenoxycarb showed stronger inhibition. The inhibitory activity of fenoxycarb, however, was more than 1000-fold lower than that of OTFP, a highly potent inhibitor of JHEs. Surprisingly, topical application of methoprene, fenoxycarb or pyriproxyfen on 6th instars of S. littoralis and S. frugiperda prevented the dramatic reduction in JHE activity that was found in control insects. Our findings suggest that JHAs may function as JH agonists that play a disruptive role or a hormonal replacement role in S. littoralis and S. frugiperda. PMID:26969437

  4. Impacts of regular and random noise on the behaviour, growth and development of larval Atlantic cod (Gadus morhua)

    PubMed Central

    Nedelec, Sophie L.; Simpson, Stephen D.; Morley, Erica L.; Nedelec, Brendan; Radford, Andrew N.

    2015-01-01

    Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod (Gadus morhua). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width–length ratios. Larvae with lower body width–length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures. PMID:26468248

  5. Impacts of regular and random noise on the behaviour, growth and development of larval Atlantic cod (Gadus morhua).

    PubMed

    Nedelec, Sophie L; Simpson, Stephen D; Morley, Erica L; Nedelec, Brendan; Radford, Andrew N

    2015-10-22

    Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod (Gadus morhua). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width-length ratios. Larvae with lower body width-length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures. PMID:26468248

  6. Starvation stress during larval development facilitates an adaptive response in adult worker honey bees (Apis mellifera L.).

    PubMed

    Wang, Ying; Kaftanoglu, Osman; Brent, Colin S; Page, Robert E; Amdam, Gro V

    2016-04-01

    Most organisms are constantly faced with environmental changes and stressors. In diverse organisms, there is an anticipatory mechanism during development that can program adult phenotypes. The adult phenotype would be adapted to the predicted environment that occurred during organism maturation. However, whether this anticipatory mechanism is present in eusocial species is questionable because eusocial organisms are largely shielded from exogenous conditions by their stable nest environment. In this study, we tested whether food deprivation during development of the honey bee (Apis mellifera), a eusocial insect model, can shift adult phenotypes to better cope with nutritional stress. After subjecting fifth instar worker larvae to short-term starvation, we measured nutrition-related morphology, starvation resistance, physiology, endocrinology and behavior in the adults. We found that the larval starvation caused adult honey bees to become more resilient toward starvation. Moreover, the adult bees were characterized by reduced ovary size, elevated glycogen stores and juvenile hormone (JH) titers, and decreased sugar sensitivity. These changes, in general, can help adult insects survive and reproduce in food-poor environments. Overall, we found for the first time support for an anticipatory mechanism in a eusocial species, the honey bee. Our results suggest that this mechanism may play a role in honey bee queen-worker differentiation and worker division of labor, both of which are related to the responses to nutritional stress. PMID:27030775

  7. Effects of proteinase inhibitor from Adenanthera pavonina seeds on short- and long term larval development of Aedes aegypti.

    PubMed

    Sasaki, Daniele Yumi; Jacobowski, Ana Cristina; de Souza, Antônio Pancrácio; Cardoso, Marlon Henrique; Franco, Octávio Luiz; Macedo, Maria Lígia Rodrigues

    2015-05-01

    Currently, one of the major global public health concerns is related to the transmission of dengue/yellow fever virus by the vector Aedes aegypti. The most abundant digestive enzymes in Ae. aegypti midgut larvae are trypsin and chymotrypsin. Since protease inhibitors have the capacity to bind to and inhibit the action of insect digestive proteinases, we investigated the short- and long-term effects of Adenanthera pavonina seed proteinase inhibitor (ApTI) on Ae. aegypti larvae, as well as a possible mechanism of adaptation. ApTI had a significant effect on Ae. aegypti larvae exposed to a non-lethal concentration of ApTI during short- and long-duration assays, decreasing survival, weight and proteinase activities of midgut extracts of larvae. The zymographic profile of ApTI demonstrated seven bands; three bands apparently have trypsin-like activity. Moreover, the peritrophic membrane was not disrupted. The enzymes of ApTI-fed larvae were found to be sensitive to ApTI and to have a normal feedback mechanism; also, the larval digestive enzymes were not able to degrade the inhibitor. In addition, ApTI delayed larval development time. Histological studies demonstrated a degeneration of the microvilli of the posterior midgut region epithelium cells, hypertrophy of the gastric caeca cells and an augmented ectoperitrophic space in larvae. Moreover, Ae. aegypti larvae were incapable of overcoming the negative effects of ApTI, indicating that this inhibitor might be used as a promising agent against Ae. aegypti. In addition, molecular modeling and molecular docking studies were also performed in order to construct three-dimensional theoretical models for ApTI, trypsin and chymotrypsin from Ae. aegypti, as well as to predict the possible interactions and affinity values for the complexes ApTI/trypsin and ApTI/chymotrypsin. In this context, this study broadens the base of our understanding about the modes of action of proteinase inhibitors in insects, as well as the way insects

  8. The effects of food shortage during larval development on adult body size, body mass, physiology and developmental time in a tropical damselfly.

    PubMed

    Jiménez-Cortés, J Guillermo; Serrano-Meneses, Martín Alejandro; Córdoba-Aguilar, Alex

    2012-03-01

    Few studies have looked jointly at the effects of larval stressors on life history and physiology across metamorphosis, especially in tropical insects. Here we investigated how the variation of food availability during the larval stage of the tropical and territorial American rubyspot damselfly (Hetaerina americana) affects adult body size and body mass, and two physiological indicators of condition--phenoloxidase activity (an indicator of immune ability) and protein concentration. We also investigated whether larval developmental time is prolonged when food is scarce, an expected situation for tropical species whose larval time is less constrained, compared to temperate species. Second instar larvae were collected from their natural environments and reared in one of two diet regimes: (i) "rich" provided with five Artemia salina prey every day, and (ii) "poor" provided with two A. salina prey every day. In order to compare how distinct our treatments were from natural conditions, a second set of last-instar larvae were also collected and allowed to emerge. Only body size and phenoloxidase increased in the rich regime, possibly to prioritize investment on sexually selected traits (which increase mating opportunities), and immune ability, given pathogen pressure. The sexes did not differ in body size in relation to food regimes but they did differ in body mass and protein concentration; this can be explained on the basis of the energetically demanding territorial activities by males (for the case of body mass), and female allocation to egg production (for the case of protein). Finally, animals delayed larval development when food was scarce, which is coherent for tropical environments. These findings provide key insights in the role of food availability in a tropical species. PMID:22085821

  9. Release of hyaluronidase during in vitro development of Ascaris suum from the third to fourth larval stage.

    PubMed

    Rhoads, M L; Fetterer, R H; Urban, J F

    2001-09-01

    An enzyme that degraded glycosaminoglycan hyaluronic acid was released during in vitro development of Ascaris suum L3 to L4. The enzyme did not hydrolyze glycosaminoglycan chondroitin sulfate A. One molecular form of hyaluronidase was detected, with a molecular weight estimated at 47.8 +/- 8.6 kDa by sucrose density gradient centrifugation and at 55.0 +/- 1.3 kDa by substrate SDS-PAGE zymography. Activity of the enzyme was optimal between pH 5.0 and 6.0, and was present at neutral pH. Hyaluronidase activity was not affected by 5 mM concentrations of cupric sulfate, zinc chloride, calcium chloride, manganese chloride or EDTA. In addition, NaCl had no effect on enzyme activity at concentrations of 0.2-1.0 M. The highest level of hyaluronidase was present in culture fluid collected between days 4 and 6 of in vitro culture, and this period corresponded with that of the highest rate of increase in the percentage of L4. The presence or absence of hyaluronic acid plays a key role in basic developmental processes of vertebrates and is regulated, in part, by hyaluronidases. Developmental processes occurring during the transition of A. suum L3 to L4 may likewise depend on hyaluronidase. In addition, the infection process of a number of organisms, including some nematodes, depends on hyaluronidase. A. suum may likewise utilize hyaluronidase to facilitate larval migration within the host. PMID:11570551

  10. Pigeonpea genotypes influence parasitization preference and survival and development of the Helicoverpa armigera larval parasitoid, Campoletis chlorideae.

    PubMed

    Hugar, Shiddalingappa V; Sharma, Hari C; Basavan Goud, Kondikallu

    2014-01-01

    Studies were undertaken to identify pigeonpea, Cajanus cajan (L.) Millspaugh and the wild relative of pigeonpea, Cajanus scarabaeoides (L.) (accession ICPW 125,) genotypes that are hospitable to the pod borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larval parasitoid, Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) for the management of this pest in pigeonpea based cropping systems. Percentage parasitization of the H. armigera larvae by the C. chlorideae females was greater under no-choice conditions than under multi-choice conditions because of forced parasitization under no-choice conditions. Lowest parasitization was recorded on the wild relative, ICPW 125, which may be due to long nonglandular hairs and low survival of H. armigera larvae. Parasitization of H. armigera larvae was greater under no-choice, dual-choice and/or multi-choice conditions on ICPL 87, ICPL 87119 and ICPL 87091, which are susceptible to H. armigera, than on the pod borer-resistant genotypes ICPL 332WR, ICPL 84060 and ICPB 2042; while survival and development of the parasitoid was better on H. armigera larvae fed on ICPL 87, ICPL 87119, LRG 41, ICP 7035 and ICPL 87091 than on ICPL 332WR, ICPL 84060, ICPB 2042 and ICPW 125. The genotypes ICPL 87, ICPL 87119, LRG 42 and ICPL 87091 that are hospitable to C. chloridae, are better suited for use in integrated pest management to minimize the losses due to H. armigera in pigeonpea. PMID:25110629

  11. A detailed staging scheme for late larval development in Strongylocentrotus purpuratus focused on readily-visible juvenile structures within the rudiment

    PubMed Central

    2014-01-01

    Background The purple sea urchin, Strongylocentrotus purpuratus, has long been the focus of developmental and ecological studies, and its recently-sequenced genome has spawned a diversity of functional genomics approaches. S. purpuratus has an indirect developmental mode with a pluteus larva that transforms after 1–3 months in the plankton into a juvenile urchin. Compared to insects and frogs, mechanisms underlying the correspondingly dramatic metamorphosis in sea urchins remain poorly understood. In order to take advantage of modern techniques to further our understanding of juvenile morphogenesis, organ formation, metamorphosis and the evolution of the pentameral sea urchin body plan, it is critical to assess developmental progression and rate during the late larval phase. This requires a staging scheme that describes developmental landmarks that can quickly and consistently be used to identify the stage of individual living larvae, and can be tracked during the final two weeks of larval development, as the juvenile is forming. Results Notable structures that are easily observable in developing urchin larvae are the developing spines, test and tube feet within the juvenile rudiment that constitute much of the oral portion of the adult body plan. Here we present a detailed staging scheme of rudiment development in the purple urchin using soft structures of the rudiment and the primordia of these juvenile skeletal elements. We provide evidence that this scheme is robust and applicable across a range of temperature and feeding regimes. Conclusions Our proposed staging scheme provides both a useful method to study late larval development in the purple urchin, and a framework for developing similar staging schemes across echinoderms. Such efforts will have a high impact on evolutionary developmental studies and larval ecology, and facilitate research on this important deuterostome group. PMID:24886415

  12. Temporal changes in the bacterial community of animal feces and their correlation with stable fly oviposition, larval development, and adult fitness

    PubMed Central

    Albuquerque, Thais A.; Zurek, Ludek

    2014-01-01

    Stable flies are blood-feeding insects with a great negative impact on animals world wide. Larvae develop primarily in animal manure and bacteria are essential for larval development; however, the principle of this dependence is not understood. We hypothesized that as the microbial community of animal manure changes over time, it plays an important role in stable fly fitness. Two-choice bioassays were conducted using 2 week old horse manure (control) and aging horse manure (fresh to 5 week old) to evaluate the effect of manure age on stable fly oviposition. Our data showed that fresh feces did not stimulate oviposition and that the attractiveness increased as manure aged but started to decline after 3 weeks. Bioassays assessing the effect of manure age at the time of oviposition on larval development demonstrated that 1–3 week old manure supported larval development significantly better than fresh, 4, and 5 week old manure. In addition, adult fitness (body size) was significantly higher in flies from 1 and 2 week old manure comparing to that of all other treatments. Analysis of the bacterial community of aging horse manure by 454-pyrosequencing of 16S rDNA revealed a great reduction in bacterial diversity and richness from fresh to 1–5 week old manure and a major shift from strict anaerobes in fresh manure to facultative anaerobes and strict aerobes in aged manure. Overall, the microbial community of 2 and 3 week old horse manure with its dominant bacterial taxa Rhizobium, Devosia, and Brevundimonas stimulated stable fly oviposition the most and provided a suitable habitat for larval development. These bacteria represent the candidates for studies focused on better understanding of stable fly – microbial interactions. PMID:25426108

  13. Relationships between chemical properties of larval media and development of two Stomoxys species (Diptera: Muscidae) from Reunion Island.

    PubMed

    Gilles, J; David, J F; Lecomte, P; Tillard, E

    2008-02-01

    The development of two cattle pests, Stomoxys calcitrans L. and Stomoxys niger niger Macquart (Diptera: Muscidae), was studied in the laboratory using seven potential larval media from a dairy farm on Reunion Island. The media were six types of cattle feed and an old manure medium. Egg-to-adult survival, duration of development, and adult live weight at emergence were determined for both fly species on each medium. The media were analyzed for pH, nitrogen, organic matter, and structural compounds (cellulose, hemicellulose, lignin). For S. calcitrans, immature survival was significantly higher on sugarcane leaves, Rhodes grass, and elephant grass; for S. niger, survival was significantly higher on the same substrates plus sugarcane tops. These substrates were characterized by slightly acid pH values (range, 5.4-6.0). In both species, there were significant bell-shape relationships between immature survival and substrate pH. The developmental time of both fly species was significantly shorter on Rhodes grass, Rhodes grass hay, and elephant grass. These substrates were characterized by high cellulose contents and low soluble organic fractions. In both species, there were significant linear relationships between developmental time and cellulose content of substrates. Similarly, there were significant linear relationships between adult live weight and cellulose content of substrates. The C:N ratio of the most favorable substrates was highly variable. Although the relationships revealed in this study do not establish causation, it is suggested that pH and cellulose content may have direct and indirect effects on Stomoxys development. PMID:18348795

  14. Development of Trichosomoides nasalis (Nematoda: Trichinelloidea) in the murid host: evidence for larval growth in striated muscle fibres

    PubMed Central

    Fall, E.H.; Diagne, M.; Junker, K.; Duplantier, J.M.; Ba, K.; Vallée, I.; Bain, O.

    2012-01-01

    Trichosomoides nasalis (Trichinelloidea) is a parasite of Arvicanthis niloticus (Muridae) in Senegal. Female worms that harbour dwarf males in their uteri, occur in the epithelium of the nasal mucosa. Young laboratory-bred A. niloticus were either fed females containing larvated eggs or intraperitoneally injected with motile first-stage larvae recovered from female uteri. Both resulted in successful infection. Organs examined during rodent necropsy were blood and lymphatic circulatory systems (heart, large vessels, lymphnodes), lungs, liver, kidneys, thoracic and abdominal cavities, thoracic and abdominal muscular walls, diaphragm, tongue, and nasal mucosa. Development to adult nasal stages took three weeks. Recovery of newly hatched larvae from the peritoneal fluid at four-eight hours after oral infection suggests a direct passage from the stomach or intestinal wall to the musculature. However, dissemination through the blood, as observed with Trichinella spiralis, cannot be excluded even though newly hatched larvae of T. nasalis are twice as thick (15 μm). Developing larvae were found in histological sections of the striated muscle of the abdominal and thoracic walls, and larvae in fourth moult were dissected from these sites. Adult females were found in the deep nasal mucosa where mating occurred prior to worms settling in the nasal epithelium. The present study shows a remarkable similarity between T. nasalis and Trichinella species regarding muscle tropism, but the development of T. nasalis is not arrested at the late first-larval stage and does not induce transformation of infected fibres into nurse cells. T. nasalis seems a potential model to study molecular relations between trichinelloid larvae and infected muscle fibres. PMID:22314237

  15. Compensatory Development and Costs of Plasticity: Larval Responses to Desiccated Conspecifics

    PubMed Central

    Sadeh, Asaf; Truskanov, Noa; Mangel, Marc; Blaustein, Leon

    2011-01-01

    Understanding constraints on phenotypic plasticity is central to explaining its evolution and the evolution of phenotypes in general, yet there is an ongoing debate on the classification and relationships among types of constraints. Since plasticity is often a developmental process, studies that consider the ontogeny of traits and their developmental mechanisms are beneficial. We manipulated the timing and reliability of cues perceived by fire salamander larvae for the future desiccation of their ephemeral pools to determine whether flexibility in developmental rates is constrained to early ontogeny. We hypothesized that higher rates of development, and particularly compensation for contradictory cues, would incur greater endogenous costs. We found that larvae respond early in ontogeny to dried conspecifics as a cue for future desiccation, but can fully compensate for this response in case more reliable but contradictory cues are later perceived. Patterns of mortality suggested that endogenous costs may depend on instantaneous rates of development, and revealed asymmetrical costs of compensatory development between false positive and false negative early information. Based on the results, we suggest a simple model of costs of development that implies a tradeoff between production costs of plasticity and phenotype-environment mismatch costs, which may potentially underlie the phenomenon of ontogenetic windows constraining plasticity. PMID:21246048

  16. Eugregarines reduce susceptibility of the hide beetle, Dermestes maculatus, to apicomplexan pathogens and retard larval development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eugregarines are abundant in a great diversity of invertebrates, and yet their relationships with their hosts are subject to controversy and confusion. We tested the effect of the eugregarine, Pyxinia crystalligera, on growth, development, and susceptibility to two Apicomplexa pathogens of the hide ...

  17. EFFECT OF DIETARY COPPER ON LARVAL DEVELOPMENT OF DIAPREPES ABBREVIATUS (COLEOPTERA: CURCULIONIDAE)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Larvae of the Diaprepes root weevil, Diaprepes abbreviatus (L.), were reared from hatching on an artificial diet containing four concentrations of two copper compounds, cupric sulfate (CuSO4) or cupric hydroxide [Cu(OH2)]. Negative effects of copper on insect development were observed only for earl...

  18. Examining cuphea as a potential host for western corn rootworm (Coleoptera: Chrysomelidae): larval development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In previous crop rotation research, adult emergence traps placed in plots planted to Cuphea PSR-23 (a selected cross of C. viscossisma and C. lanceolata) caught high numbers of adult western corn rootworms, Diabrotica virgifera virgifera LeConte, suggesting that larvae may have completed development...

  19. [Larval development and determinism of nymphal diapause in a Lepidoptera, Actias selene Hbn. (Attacidae) (author's transl)].

    PubMed

    Vuillaume, M; Bergerard, J

    1977-05-15

    Actias selene has been reared under different conditions of lights, photophases and temperatures. The red light (630-670 nm) corresponding to the maximum of absorption of pterobilin and phorcabilin chromoproteins reduces the average length of development from 29 days to 50 days and totally inhibits the nymphal diapause. The results are discussed. PMID:862788

  20. The toxicity of a lipid transfer protein (Cc-LTP1) from Coffea canephora Seeds on the larval development of Callosobruchus maculatus (Coleoptera: Bruchidae).

    PubMed

    Zottich, Umberto; Da Cunha, Maura; Dias, Germana B; Rabelo, Guilherme R; Oliveira, Antonia Elenir A; Carvalho, André O; Fernandes, Kátia Valevski S; do Nascimento, Viviane V; Gomes, Valdirene M

    2014-10-01

    In this work, we analyzed the effects of coffee seed proteins, especially Cc-LTP1 on the larval development of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), a bruchid pest of beans and the most important insect pest of Vigna unguiculata (L.) Walp. Artificial seed assay, which incorporated the F/0-90 fraction from Coffea canephora seeds, resulted in the reduction of oviposition and caused an inhibition of C. maculatus larval development in a dose-dependent manner. The F/0-90 fraction used at a 4 % concentration resulted in the survival of no larvae. The purified Cc-LTP1, at a concentration of 0.5 %, also demonstrated effective inhibition of larval development, reducing both females oviposition and the weight and number of larvae. Cc-LTP1 was also able to inhibit the C. maculatus gut α-amylase activity, and immunolabeling by an anti-LTP serum was observed in the midgut tissues of the C. maculatus larvae. Cc-LTP1 has shown binding affinity towards microvillar cells, endoplasmic reticulum and mitochondria, as demonstrated by micrographic images taken by a transmission electron microscope. The results from this study indicate that Cc-LTP1 has insecticidal actions toward C. maculatus and exerts anti-nutritional effects with direct actions on intestinal tissues. PMID:25097041

  1. A binding site for Bacillus thuringiensis Cry1Ab toxin is lost during larval development in two forest pests.

    PubMed

    Rausell, C; Martínez-Ramírez, A C; García-Robles, I; Real, M D

    2000-04-01

    The insecticidal activity and receptor binding properties of Bacillus thuringiensis Cry1A toxins towards the forest pests Thaumetopoea pityocampa (processionary moth) and Lymantria monacha (nun moth) were investigated. Cry1Aa, Cry1Ab, and Cry1Ac were highly toxic (corresponding 50% lethal concentration values: 956, 895, and 379 pg/microl, respectively) to first-instar T. pityocampa larvae. During larval development, Cry1Ab and Cry1Ac toxicity decreased with increasing age, although the loss of activity was more pronounced for Cry1Ab. Binding assays with (125)I-labelled Cry1Ab and brush border membrane vesicles from T. pityocampa first- and last-instar larvae detected a remarkable decrease in the overall Cry1Ab binding affinity in last-instar larvae, although saturable Cry1Ab binding to both instars was observed. Homologous competition experiments demonstrated the loss of one of the two Cry1Ab high-affinity binding sites detected in first-instar larvae. Growth inhibition assays with sublethal doses of Cry1Aa, Cry1Ab, and Cry1Ac in L. monacha showed that all three toxins were able to delay molting from second instar to third instar. Specific saturable binding of Cry1Ab was detected only in first- and second-instar larvae. Cry1Ab binding was not detected in last-instar larvae, although specific binding of Cry1Aa and Cry1Ac was observed. These results demonstrate a loss of Cry1Ab binding sites during development on the midgut epithelium of T. pityocampa and L. monacha, correlating in T. pityocampa with a decrease in Cry1Ab toxicity with increasing age. PMID:10742241

  2. A Binding Site for Bacillus thuringiensis Cry1Ab Toxin Is Lost during Larval Development in Two Forest Pests

    PubMed Central

    Rausell, Carolina; Martínez-Ramírez, Amparo Consuelo; García-Robles, Inmaculada; Real, María Dolores

    2000-01-01

    The insecticidal activity and receptor binding properties of Bacillus thuringiensis Cry1A toxins towards the forest pests Thaumetopoea pityocampa (processionary moth) and Lymantria monacha (nun moth) were investigated. Cry1Aa, Cry1Ab, and Cry1Ac were highly toxic (corresponding 50% lethal concentration values: 956, 895, and 379 pg/μl, respectively) to first-instar T. pityocampa larvae. During larval development, Cry1Ab and Cry1Ac toxicity decreased with increasing age, although the loss of activity was more pronounced for Cry1Ab. Binding assays with 125I-labelled Cry1Ab and brush border membrane vesicles from T. pityocampa first- and last-instar larvae detected a remarkable decrease in the overall Cry1Ab binding affinity in last-instar larvae, although saturable Cry1Ab binding to both instars was observed. Homologous competition experiments demonstrated the loss of one of the two Cry1Ab high-affinity binding sites detected in first-instar larvae. Growth inhibition assays with sublethal doses of Cry1Aa, Cry1Ab, and Cry1Ac in L. monacha showed that all three toxins were able to delay molting from second instar to third instar. Specific saturable binding of Cry1Ab was detected only in first- and second-instar larvae. Cry1Ab binding was not detected in last-instar larvae, although specific binding of Cry1Aa and Cry1Ac was observed. These results demonstrate a loss of Cry1Ab binding sites during development on the midgut epithelium of T. pityocampa and L. monacha, correlating in T. pityocampa with a decrease in Cry1Ab toxicity with increasing age. PMID:10742241

  3. The silkworm glutathione S-transferase gene noppera-bo is required for ecdysteroid biosynthesis and larval development.

    PubMed

    Enya, Sora; Daimon, Takaaki; Igarashi, Fumihiko; Kataoka, Hiroshi; Uchibori, Miwa; Sezutsu, Hideki; Shinoda, Tetsuro; Niwa, Ryusuke

    2015-06-01

    Insect molting and metamorphosis are tightly controlled by ecdysteroids, which are important steroid hormones that are synthesized from dietary sterols in the prothoracic gland. One of the ecdysteroidogenic genes in the fruit fly Drosophila melanogaster is noppera-bo (nobo), also known as GSTe14, which encodes a member of the epsilon class of glutathione S-transferases. In D. melanogaster, nobo plays a crucial role in utilizing cholesterol via regulating its transport and/or metabolism in the prothoracic gland. However, it is still not known whether the orthologs of nobo from other insects are also involved in ecdysteroid biosynthesis via cholesterol transport and/or metabolism in the prothoracic gland. Here we report genetic evidence showing that the silkworm Bombyx mori ortholog of nobo (nobo-Bm; GSTe7) is essential for silkworm development. nobo-Bm is predominantly expressed in the prothoracic gland. To assess the functional importance of nobo-Bm, we generated a B. mori genetic mutant of nobo-Bm using TALEN-mediated genome editing. We show that loss of nobo-Bm function causes larval arrest and a glossy cuticle phenotype, which are rescued by the application of 20-hydroxyecdysone. Moreover, the prothoracic gland cells isolated from the nobo-Bm mutant exhibit an abnormal accumulation of 7-dehydrocholesterol, a cholesterol metabolite. These results suggest that the nobo family of glutathione S-transferases is essential for development and for the regulation of sterol utilization in the prothoracic gland in not only the Diptera but also the Lepidoptera. On the other hand, loss of nobo function mutants of D. melanogaster and B. mori abnormally accumulates different sterols, implying that the sterol utilization in the PG is somewhat different between these two insect species. PMID:25881968

  4. Regional expression of Pax7 in the brain of Xenopus laevis during embryonic and larval development

    PubMed Central

    Bandín, Sandra; Morona, Ruth; Moreno, Nerea; González, Agustín

    2013-01-01

    Pax7 is a member of the highly conserved Pax gene family that is expressed in restricted zones of the central nervous system (CNS) during development, being involved in early brain regionalization and the maintenance of the regional identity. Using sensitive immunohistochemical techniques we have analyzed the spatiotemporal pattern of Pax7 expression in the brain of the anuran amphibian Xenopus laevis, during development. Pax7 expression was first detected in early embryos in the basal plate of prosomere 3, roof and alar plates of prosomere 1 and mesencephalon, and the alar plate of rhombomere 1. As development proceeded, Pax7 cells were observed in the hypothalamus close to the catecholaminergic population of the mammillary region. In the diencephalon, Pax7 was intensely expressed in a portion of the basal plate of prosomere 3, in the roof plate and in scattered cells of the thalamus in prosomere 2, throughout the roof of prosomere 1, and in the commissural and juxtacommissural domains of the pretectum. In the mesencephalon, Pax7 cells were localized in the optic tectum and, to a lesser extent, in the torus semicircularis. The rostral portion of the alar part of rhombomere 1, including the ventricular layer of the cerebellum, expressed Pax7 and, gradually, some of these dorsal cells were observed to populate ventrally the interpeduncular nucleus and the isthmus (rhombomere 0). Additionally, Pax7 positive cells were found in the ventricular zone of the ventral part of the alar plate along the rhombencephalon and the spinal cord. The findings show that the strongly conserved features of Pax7 expression through development shared by amniote vertebrates are also present in the anamniote amphibians as a common characteristic of the brain organization of tetrapods. PMID:24399938

  5. DNA polymerases alpha and gamma during pre-emergence and early larval development of Artemia.

    PubMed

    Slater, J M; McLennan, A G

    1982-12-15

    DNA polymerases alpha and gamma have been studied in cryptobiotic cysts and developing embryos and larvae of the brine shrimp Artemia. The two enzymes readily separate on Cibacron blue 3-GA Matrex gel. Assay requirements with activated DNA as primer-template are pH 8.0, 1 mM Mg2+, 50 mM K+ for DNA polymerase alpha and pH 8.4, 10 mM Mg2+, 80 mM K+ for DNA polymerase gamma. DNA polymerase alpha is inhibited by N-ethylmaleimide (94% and 100% at 1 mM and 10 mM respectively) and aphidicolin (96% at 60 microM). DNA polymerase gamma is also sensitive to N-ethylmaleimide (83% and 100% inhibition at 1 mM and 10 mM respectively) but is resistant to aphidicolin. 2',3'-Dideoxythymidine 5'-triphosphate (ddTTP) inhibits the gamma polymerase by 88% when in fivefold excess over dTTP whereas the alpha polymerase is unaffected by this compound. DNA polymerase alpha has a sedimentation coefficient of 7.6 S which is reduced to 6.2 S by a phenylmethylsulphonyl fluoride-sensitive proteinase. The gamma polymerase sediments at 8.3 S. No DNA polymerase beta activity could be detected. After the reinitiation of development both activities increased twofold up to 8 h (gamma polymerase) and 16 h (alpha polymerase), then declined before the onset of nuclear DNA replication after hatching. Thymidine kinase activity increased over 200-fold up to the time of replication. Analysis on Percoll density gradients of the intracellular distribution of both polymerases during development suggests that the changes in their activities may be due to migration from storage sites to replication complexes in the nuclei and mitochondria. The content of the mitochondrial DNA polymerase gamma in different batches of cysts may reflect the relative viabilities of the cysts. PMID:7151804

  6. Gonadal development of larval male Xenopus laevis exposed to atrazine in outdoor microcosms

    USGS Publications Warehouse

    Jooste, A.M.; Du Preez, L.H.; Carr, J.A.; Giesy, J.P.; Gross, T.S.; Kendall, R.J.; Smith, E.E.; Van Der Kraak, G. L.; Solomon, K.R.

    2005-01-01

    The potential effects of atrazine on gonadal development in metamorphs and subadults of the African clawed frog (Xenopus laevis) were studied under conditions of natural photoperiod and temperatures in outdoor microcosms from August 2002 to June 2003 in South Africa. Triplicate 1100 L microcosms for each nominal concentration of 0.0, 1, 10, and 25 ??g of atrazine/L were used. Measured atrazine concentrations varied <25% throughout the study, and no atrazine was detected in the control microcosms. Tadpoles developed well at all concentrations. On the basis of histological examination of testes of recently metamorphosed stage 66 frogs, 57% of the individuals in the reference group exhibited testicular oocytes as compared with 57, 59, and 39% of the 1, 10, and 25 ??g/L atrazine groups, respectively. The average prevalence of testicular oocytes for all of the treatments including the controls was 54% in a single testis, while, in 35% of individuals, testicular oocytes were observed in both testes. The number of testicular oocytes per individual ranged from 0 to 58 with means of 9.5, 9.8, 8.5, and 11.1 for the 0.0, 1, 10, and 25 ??g of atrazine/L groups, respectively. Ten months after metamorphosis, another subset of juveniles was examined, and the maximum number of testicular oocytes observed was five in one animal. The presence of testicular oocytes was not related to exposure to atrazine and may be a natural phenomenon during ontogeny. ?? 2005 American Chemical Society.

  7. Effects of Sediment Containing Coal Ash from the Kingston Ash Release on Embryo-Larval Development in the Fathead Minnow, Pimephales promelas (Rafinesque, 1820)

    SciTech Connect

    Greeley Jr, Mark Stephen; Elmore, Logan R; McCracken, Kitty; Sherrard, Rick

    2014-01-01

    The largest environmental release of coal ash in U.S. history occurred in December 2008 with the failure of a retention structure at the Tennessee Valley Authority (TVA) Kingston Fossil Plant in East Tennessee. A byproduct of coal-burning power plants, coal ash is enriched in metals and metalloids such as selenium and arsenic with known toxicity to fish including embryonic and larval stages. The effects of contact exposure to sediments containing up to 78 % coal ash from the Kingston spill on the early development of fish embryos and larvae were examined in 7-day laboratory tests with the fathead minnow (Pimephales promelas). No significant effects were observed on hatching success, incidences of gross developmental abnormalities, or embryo-larval survival. Results suggest that direct exposures to sediment containing residual coal ash from the Kingston ash release may not present significant risks to fish eggs and larvae in waterways affected by the spill.

  8. Mosquito larval habitat mapping using remote sensing and GIS: Implications of coalbed methane development and the West Nile Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potential larval habitats of the mosquito Culex tarsalis (Coquillett), implicated as a primary vector of West Nile virus in Wyoming, were identified using integrated remote sensing and geographic information sytem (GIS) analyses. The study area is in the Powder River Basin of north central Wyoming,...

  9. Control of larval and egg development in Aedes aegypti with Ribonucleic acid interference (RNAi) against juvenile hormone acid methyl transferase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ribonucleic acid interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including mosquitoes and many other insects. Little has been done, however, to harness this approach in order to control adult and larval mosquitoes. Juvenile hormone (JH) plays a pi...

  10. Development of a molecular assay to detect predation on Anopheles gambiae complex larval stages.

    PubMed

    Schielke, Erika; Costantini, Carlo; Carchini, Gianmaria; Sagnon, N'falé; Powell, Jeffrey; Caccone, Adalgisa

    2007-09-01

    We developed a molecular assay to detect predation on Anopheles gambiae sensu lato (s.l.) mosquitoes. This intergenic spacer ribosomal DNA polymerase chain reaction assay and restriction enzyme analysis uses An. gambiae-specific primers to detect mosquito DNA in the DNA extracts from whole invertebrate predators, which enables identification of species (An. gambiae s.s. versus An. arabiensis) and molecular forms (M versus S in An. gambiae s.s.). We show that An. gambiae s.l. DNA can be detected after ingestion by members of the families Lestidae (order Odonata) after four hours, Libellulidae (order Odonata) after six hours, and Notonectidae (order Hemiptera) after 24 hours. This method is an improvement over previously published methods because of ease of execution and increased time of detection after ingestion. PMID:17827361

  11. Long-distance cell migration during larval development in the appendicularian, Oikopleura dioica.

    PubMed

    Kishi, Kanae; Onuma, Takeshi A; Nishida, Hiroki

    2014-11-15

    The appendicularian, Oikopleura dioica, is a planktonic chordate. Its simple and transparent body, invariant cell lineages and short life cycle of 5 days make it a promising model organism for studies of chordate development. Here we describe the cell migration that occurs during development of the O. dioica larva. Using time-lapse imaging facilitated by florescent labeling of cells, three cell populations exhibiting long-distance migration were identified and characterized. These included (i) a multinucleated oral gland precursor that migrates anteriorly within the trunk region and eventually separates into the left and right sides, (ii) endodermal strand cells that are collectively retracted from the tail into the trunk in a tractor movement, and (iii) two subchordal cell precursors that individually migrate out from the trunk to the tip of the tail. The migration of subchordal cell precursors starts when all of the endodermal strand cells enter the trunk, and follows the same path but in a direction opposite to that of the latter. Labeling of these cells with a photoconvertible fluorescent protein, Kaede, demonstrated that the endodermal strand cells and subchordal cell precursors have distinct origins and eventual fates. Surgical removal of the trunk from the tail demonstrated that the endodermal strand cells do not require the trunk for migration, and that the subchordal cell precursors would be attracted by the distal part of the tail. This well-defined, invariant and traceable long-distance cell migration provides a unique experimental system for exploring the mechanisms of versatile cell migration in this simple organism with a chordate body plan. PMID:25224225

  12. Effects of Three Volatile Oxylipins on Colony Development in Two Species of Fungi and on Drosophila Larval Metamorphosis.

    PubMed

    Yin, Guohua; Padhi, Sally; Lee, Samantha; Hung, Richard; Zhao, Guozhu; Bennett, Joan W

    2015-09-01

    The aim of this study is to investigate the effects of three volatile oxylipins on colony development in two fungi and on Drosophila larval metamorphosis. Using an airborne exposure technique, three common and volatile oxylipins (1-octen-3-ol, (E)-2-hexenal, and 1-hexanol) were compared for their effects on spore germination and colony growth in Aspergillus niger and Penicillium chrysogenum, as well as for their effects on the morphogenesis of larvae of Drosophila melanogaster. Conidia of both A. niger and P. chrysogenum plated in the presence of low concentrations (50 ppm) of these three volatile organic compounds (VOCs) formed fewer colony-forming units (CFUs) and exhibited reduced radial growth of colonies as compared to controls. When A. niger and P. chrysogenum spores were germinated in the presence of the enantiomers of 1-octen-3-ol, (R)-(-)-1-octen-3-ol had the greatest impact on colony morphology (decreased sporulation and colony diameter), while (S)-(+)-1-octen-3-ol and the racemic form yielded similar morphological changes but to a lesser extent. In addition, Drosophila larvae exposed to vapors of these oxylipins exhibited serious delays in metamorphosis and toxic effects on pupae and adult stages. Low concentration of these three VOCs can significantly inhibit the formation of CFUs and the growth of fungi. (R)-(-)-1-octen-3-ol imposed the greatest impact on fungal morphology compared to (S)-(+)-1-octen-3-ol and the racemic form. The three volatile oxylipins could also delay the metamorphosis of Drosophila and impose toxic effects on its pupae and adult stages. PMID:26126831

  13. Development of ovary structures in the last larval and adult stages of psyllids (Insecta, Hemiptera, Sternorrhyncha: Psylloidea).

    PubMed

    Kot, Marta; Büning, Jürgen; Jankowska, Władysława; Drohojowska, Jowita; Szklarzewicz, Teresa

    2016-07-01

    The development and organization of the ovaries of ten species from four Psylloidea families (Psyllidae, Triozidae, Aphalaridae and Liviidae) have been investigated. The ovaries of the last larval stage (i.e. fifth instar) of all examined species are filled with numerous clusters of cystocytes which undergo synchronous incomplete mitotic division. Cystocytes of the given cluster are arranged into a rosette with polyfusome in the centre. These clusters are associated with single somatic cells. At the end of the fifth instar, the clusters begin to separate from each other, forming spherical ovarioles which are surrounded by a single layer of somatic cells. In the ovarioles of very young females all cystocytes enter the prophase of meiosis and differentiate shortly thereafter into oocytes and trophocytes (nurse cells). Meanwhile, somatic cells differentiate into cells of the inner epithelial sheath surrounding the trophocytes and into the prefollicular cells that encompass the oocytes. During this final differentiation, the trophocytes lose their cell membranes and become syncytial. Oocytes remain cellular and most of them (termed arrested oocytes) do not grow. In the ovarioles of older females, one oocyte encompassed by its follicle cells starts growing, still connected to the syncytial tropharium by a nutritive cord. After the short phase of previtellogenesis alone, the oocyte enters its vitellogenic the growth phase in the vitellarium. At that time, the second oocyte may enter the vitellarium and start its previtellogenic growth. In the light of the obtained results, the phylogeny of psyllids, as well as phylogenetic relationships between taxa of Hemiptera: Sternorrhyncha are discussed. PMID:27140505

  14. Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic and early larval development

    PubMed Central

    2013-01-01

    Background Nutritional symbioses play a central role in insects’ adaptation to specialized diets and in their evolutionary success. The obligatory symbiosis between the pea aphid, Acyrthosiphon pisum, and the bacterium, Buchnera aphidicola, is no exception as it enables this important agricultural pest insect to develop on a diet exclusively based on plant phloem sap. The symbiotic bacteria provide the host with essential amino acids lacking in its diet but necessary for the rapid embryonic growth seen in the parthenogenetic viviparous reproduction of aphids. The aphid furnishes, in exchange, non-essential amino acids and other important metabolites. Understanding the regulations acting on this integrated metabolic system during the development of this insect is essential in elucidating aphid biology. Results We used a microarray-based approach to analyse gene expression in the late embryonic and the early larval stages of the pea aphid, characterizing, for the first time, the transcriptional profiles in these developmental phases. Our analyses allowed us to identify key genes in the phenylalanine, tyrosine and dopamine pathways and we identified ACYPI004243, one of the four genes encoding for the aspartate transaminase (E.C. 2.6.1.1), as specifically regulated during development. Indeed, the tyrosine biosynthetic pathway is crucial for the symbiotic metabolism as it is shared between the two partners, all the precursors being produced by B. aphidicola. Our microarray data are supported by HPLC amino acid analyses demonstrating an accumulation of tyrosine at the same developmental stages, with an up-regulation of the tyrosine biosynthetic genes. Tyrosine is also essential for the synthesis of cuticular proteins and it is an important precursor for cuticle maturation: together with the up-regulation of tyrosine biosynthesis, we observed an up-regulation of cuticular genes expression. We were also able to identify some amino acid transporter genes which are

  15. Differential toxicity and uptake of Diazinon on embryo-larval development of Rhinella arenarum.

    PubMed

    Aronzon, Carolina Mariel; Marino, Damián J G; Ronco, Alicia E; Pérez Coll, Cristina Silvia

    2014-04-01

    Diazinon, an anti-cholinesterase organophosphate, is an extensively used pesticide. The main objective of this work was to assess the lethal and sublethal effects of Diazinon and its comparison with the uptake by embryos and larvae of the common South American toad Rhinella arenarum by means of standardized bioassays during acute (96 h), short-term chronic (168 h) and chronic (504 h) exposures. Toxicity resulted time- and stage-dependent, thus the lethal concentration 50 for 96 h, 168 h and 504 h were 27.2; 20.1 and 6.8 mg Diazinon L(-1) for embryos and 8, 6.7 and 1.9 mg Diazinon L(-1) for larvae. It is noteworthy the remarkable differences found in the concentration which caused lethality with those causing adverse effects on development such as malformations (teratogenic effects). Therefore, the teratogenic index from 144 h was greater than two; the main adverse effects were axial flexures, irregular borders, wavy tail, microcephaly, malformed mouth and adhesive structures, gut miscoiling, underdeveloped gills, cloacal edema, desquamation and severe hydropsy. Moreover, the characteristic sublethal effect of Diazinon on larvae was abnormal behavior related to neurotoxicity with a NOEC-168 h of 4.5 mg Diazinon L(-1). Diazinon contents in R. arenarum were time-dependent and significantly related to exposure concentration for both embryos and larvae. Diazinon contents were also stage-dependent, as it was up to 27 times higher for organisms exposed from blastula stage onwards than early larvae. These facts and the Hazard Quotients, a numerical expression of ecological risk, of 2.73, which is above USEPA's Level of Concern, showed the threat that Diazinon represents for R. arenarum populations. PMID:24485812

  16. The interplay of adult and larval time constraints shapes species differences in larval life history.

    PubMed

    Mikolajewski, Dirk J; De Block, Marjan; Stoks, Robby

    2015-04-01

    In animals with a complex life cycle, larval life-history plasticity is likely shaped by the interplay of selective factors in both larval and adult stages. A wide interspecific variation in responses to larval time constraints imposed by seasonality has been documented. Few studies have addressed differences among closely related species in the evolutionary trajectories of age and size at metamorphosis and their link with larval growth rate under time constraints. None have considered how species-specific length of the reproductive season affects larval developmental responses to time constraints. We tested in four Coenagrion damselfly species whether species with a longer reproductive season, facing a smaller threat of missing out on reproduction, react less to larval time constraints and pre-winter food shortage by accelerating development rate and growth rate, and therefore pay less physiological costs. All species increased development and growth rates under larval time constraints. The magnitude of this increase negatively correlated across species with the length of the reproductive season. Under larval time constraints, only the species exhibiting the longest reproductive season suffered a delayed emergence and a reduced investment in energy storage, yet also showed an increased immune function. Under a longer reproductive season, evolution may favor compensation for larval constraints after metamorphosis. Growth rate was accelerated after pre-winter food shortage to the same extent across species; effects on age and mass at emergence also did not differ among species. Time constraints associated with the length of the reproductive season may predictably contribute to species differences in their response to time constraints imposed in the larval stage. Our study adds empirical proof that the interplay of selective factors in the larval and adult stages may determine life-history plasticity with regard to larval time constraints. PMID:26230032

  17. Expression analysis of the insulin-like growth factors I and II during embryonic and early larval development of turbot ( Scophthalmus maximus)

    NASA Astrophysics Data System (ADS)

    Wen, Haishen; Qi, Qian; Hu, Jian; Si, Yufeng; He, Feng; Li, Jifang

    2015-04-01

    The insulin-like growth factors I and II (IGF-I and IGF-II) are important proteins involved in fish growth and development. Here, we report the isolation of IGF-II and expression analysis of IGFs in turbot Scophthalmus maximus, aiming to clarify their function in embryonic and larval development of fish. The deduced IGF-II gene is 808 bp in full length, which encodes a protein of 219 amino acids and is 93% similar with that of Paralichthys olicaceus in amino acid sequence. The tissue abundance and the expression pattern of IGFs in a turbot at early development stages were investigated via reverse transcription-polymer chain reaction. Result showed that the IGF-I and IGF-II genes were widely expressed in tissues of S. maximus. IGF-I was detected in all tissues except intestines with the highest level in liver, while IGF-II transcript presented in all tissues except muscle. At the stages of embryonic and larval development, the mRNA levels of IGFs sharply increased from the stage of unfertilized egg to post larva, followed by a decrease with larval development. However, there was an increase in IGF-I at the embryonic stage and IGF-II at the gastrula stage, respectively. These results suggested that IGFs play important roles in cell growth and division of the turbot. Our study provides reference data for further investigation of growth regulation in turbot, which can guarantee better understanding of the physiological role that IGFs play in fish.

  18. Effects of chronic exposure to soft, acidic water on gill development and chloride cell numbers in embryo-larval brook trout, Salvelinus fontinalis

    USGS Publications Warehouse

    Conklin, D.J.; Mowbray, R.C.; Gingerich, W.H.

    1992-01-01

    Recruitment failure is considered to be a major factor contributing to the decline of fish populations in soft, acidic waters; direct mortality of embryo-larval fishes has been postulated as a major cause of the decline. Little is understood of the physiological consequences to embryo-larval fishes of prolonged exposure to soft, acidic waters; however, dysfunction of respiratory and ionoregulatory processes is suspected. In order to evaluate the effects of acid exposure on the respiratory and ionoregulatory systems of developing brook trout, Salvelinus fontinalis, differences in gill morphology and numbers of chloride cells were compared between groups cf developing embryo-larval fish continuously exposed to moderately hard well water (130.0 mg.l-1 as CaCO3, pH 7.94) or to reconstituted soft, acidic water (4.4 mg.l-1 as CaCO3, pH 5.25) designed to mimic acidic waters of northern Wisconsin acidified lakes. Exposures were maintained for up to 48 days (82 days after fertilization) during critical periods of growth and differentiation of branchial structures. The second right gill arch of each fish was examined for changes in the development of filaments and lamellae and for differences in numbers of chloride cells. Gills of fish that developed in soft, acidic water contained greater numbers of normal and degenerating chloride cells, exhibited hyperplasia of primary epithelium and multiple fusions of adjacent filaments and lamellar epithelium than the gills of control fish. Filament and lamellar lengths and numbers of lamellae per filament were significantly less (P< 0.05) in fish that developed in soft, acidic water than in fish exposed to well water.

  19. A larval Devonian lungfish.

    PubMed

    Thomson, Keith S; Sutton, Mark; Thomas, Bethia

    2003-12-18

    Perhaps the most enduring of puzzles in palaeontology has been the identity of Palaeospondylus gunni Traquair, a tiny (5-60-mm) vertebrate fossil from the Middle Devonian period (approximately 385 Myr ago) of Scotland, first discovered in 1890 (refs 1-3). It is known principally from a single site (Achanarras Quarry, Caithness) where, paradoxically, it is extremely abundant, preserved in varved lacustrine deposits along with 13 other genera of fishes. Here we show that Palaeospondylus is the larval stage of a lungfish, most probably Dipterus valenciennesi Sedgwick and Murchison 1828 (ref. 5), and that development of the adult form requires a distinct metamorphosis. Palaeospondylus is the oldest known true larva of a vertebrate. PMID:14685237

  20. Use of an Activated Beta-Catenin to Identify Wnt Pathway Target Genes in Caenorhabditis elegans, Including a Subset of Collagen Genes Expressed in Late Larval Development

    PubMed Central

    Jackson, Belinda M.; Abete-Luzi, Patricia; Krause, Michael W.; Eisenmann, David M.

    2014-01-01

    The Wnt signaling pathway plays a fundamental role during metazoan development, where it regulates diverse processes, including cell fate specification, cell migration, and stem cell renewal. Activation of the beta-catenin−dependent/canonical Wnt pathway up-regulates expression of Wnt target genes to mediate a cellular response. In the nematode Caenorhabditis elegans, a canonical Wnt signaling pathway regulates several processes during larval development; however, few target genes of this pathway have been identified. To address this deficit, we used a novel approach of conditionally activated Wnt signaling during a defined stage of larval life by overexpressing an activated beta-catenin protein, then used microarray analysis to identify genes showing altered expression compared with control animals. We identified 166 differentially expressed genes, of which 104 were up-regulated. A subset of the up-regulated genes was shown to have altered expression in mutants with decreased or increased Wnt signaling; we consider these genes to be bona fide C. elegans Wnt pathway targets. Among these was a group of six genes, including the cuticular collagen genes, bli-1col-38, col-49, and col-71. These genes show a peak of expression in the mid L4 stage during normal development, suggesting a role in adult cuticle formation. Consistent with this finding, reduction of function for several of the genes causes phenotypes suggestive of defects in cuticle function or integrity. Therefore, this work has identified a large number of putative Wnt pathway target genes during larval life, including a small subset of Wnt-regulated collagen genes that may function in synthesis of the adult cuticle. PMID:24569038

  1. Larval development assays reveal the presence of sub-populations showing high- and low-level resistance in a monepantel (Zolvix(®))-resistant isolate of Haemonchus contortus.

    PubMed

    Raza, Ali; Lamb, Jane; Chambers, Michael; Hunt, Peter W; Kotze, Andrew C

    2016-04-15

    Resistance to the amino-acetonitrile derivative monepantel has been reported in several species of gastrointestinal nematodes over recent years. We were interested in the use of in vitro assays with free-living worm life-stages to detect resistance to this drug. We therefore used larval development and larval migration assays to examine dose response relationships for the drug against two susceptible and one resistant isolate of Haemonchus contortus. The resistant isolate was established by laboratory propagation of the survivors of a field treatment with Zolvix(®) that had originally resulted in a drug efficacy of over 99%. Drug efficacy against this field-derived laboratory-propagated resistant isolate in vivo was approximately 15%. The larval development assay proved able to discriminate between the susceptible and resistant isolates, with larvae of the resistant isolate showing an ability to develop at higher drug concentrations than the two susceptible isolates. The resistant isolate showed the presence of two distinct subpopulations, separated by a plateau in the dose-response curve. Sub-population 1 (approximately 40% of the total population) showed a low level of resistance with an IC50 increased approximately 7-fold compared to the baseline susceptible isolate, while sub-population 2 (the remaining 60% of the total population) showed an IC50 increased over 1000-fold compared to the baseline susceptible isolate. This level of resistance is unusually high for any gastrointestinal nematode species in drug dose-response in vitro assays. In contrast, the migration assay could not discriminate between the three isolates, with migration not reduced to zero at any of the drug concentrations tested. This study demonstrates that a larval development assay is able to detect resistance to monepantel in H. contortus, and that resistance can exist in two distinct forms. This suggests that at least two separate monepantel resistance mechanisms are acting within the worm

  2. The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci

    PubMed Central

    Pratchett, Morgan S.; Kerr, Alexander M.; Rivera-Posada, Jairo A.

    2016-01-01

    Variation in local environmental conditions can have pronounced effects on the population structure and dynamics of marine organisms. Previous studies on crown-of-thorns starfish, Acanthaster planci, have primarily focused on effects of water quality and nutrient availability on larval growth and survival, while the role of maternal nutrition on reproduction and larval development has been overlooked. To examine the effects of maternal nutrition on oocyte size and early larval development in A. planci, we pre-conditioned females for 60 days on alternative diets of preferred coral prey (Acropora abrotanoides) versus non-preferred coral prey (Porites rus) and compared resulting gametes and progeny to those produced by females that were starved over the same period. Females fed ad libitum with Acropora increased in weight, produced heavier gonads and produced larger oocytes compared to Porites-fed and starved females. Fed starfish (regardless of whether it was Acropora or Porites) produced bigger larvae with larger stomachs and had a higher frequency of normal larvae that reached the late bipinnaria / early brachiolaria stage compared to starved starfish. Females on Acropora diet also produced a higher proportion of larvae that progressed to more advanced stages faster compared to Porites-fed starfish, which progressed faster than starved starfish. These results suggest that maternal provisioning can have important consequences for the quality and quantity of progeny. Because food quality (coral community structure) and quantity (coral abundance) varies widely among reef locations and habitats, local variation in maternal nutrition of A. planci is likely to moderate reproductive success and may explain temporal and spatial fluctuations in abundance of this species. PMID:27327627

  3. The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci.

    PubMed

    Caballes, Ciemon Frank; Pratchett, Morgan S; Kerr, Alexander M; Rivera-Posada, Jairo A

    2016-01-01

    Variation in local environmental conditions can have pronounced effects on the population structure and dynamics of marine organisms. Previous studies on crown-of-thorns starfish, Acanthaster planci, have primarily focused on effects of water quality and nutrient availability on larval growth and survival, while the role of maternal nutrition on reproduction and larval development has been overlooked. To examine the effects of maternal nutrition on oocyte size and early larval development in A. planci, we pre-conditioned females for 60 days on alternative diets of preferred coral prey (Acropora abrotanoides) versus non-preferred coral prey (Porites rus) and compared resulting gametes and progeny to those produced by females that were starved over the same period. Females fed ad libitum with Acropora increased in weight, produced heavier gonads and produced larger oocytes compared to Porites-fed and starved females. Fed starfish (regardless of whether it was Acropora or Porites) produced bigger larvae with larger stomachs and had a higher frequency of normal larvae that reached the late bipinnaria / early brachiolaria stage compared to starved starfish. Females on Acropora diet also produced a higher proportion of larvae that progressed to more advanced stages faster compared to Porites-fed starfish, which progressed faster than starved starfish. These results suggest that maternal provisioning can have important consequences for the quality and quantity of progeny. Because food quality (coral community structure) and quantity (coral abundance) varies widely among reef locations and habitats, local variation in maternal nutrition of A. planci is likely to moderate reproductive success and may explain temporal and spatial fluctuations in abundance of this species. PMID:27327627

  4. New species of Scalibregmatidae (Annelida, Polychaeta) from the East Antarctic Peninsula including a description of the ecology and post-larval development of species of Scalibregma and Oligobregma.

    PubMed

    Blake, James A

    2015-01-01

    A large collection of scalibregmatid polychaetes from the east Antarctic Peninsula in May 2000 has yielded specimens of three new species of Scalibregma, Pseudoscalibregma, and Oligobregma. The new species of Scalibregma is represented by more than 400 specimens that include post-larval and juvenile forms which, for the first time, provide data on the sequence of development of key characters of a scalibregmatid. These data demonstrate that taxonomic characters including the form of the prostomium and presence of branchiae develop late in ontogeny and that small specimens cannot be reliably referred to a species or genus without a growth sequence. Juvenile morphology is also presented for the new species of Oligobregma. The new species of Scalibregma is compared with five northern hemisphere species and differs in details of the peristomium, upper and lower lips of the mouth, dorsal and ventral cirri, and nature of the short spinous setae of setiger 1. The new species of Pseudoscalibregma is unique in the nature of asymmetrical ventral cirri of posterior setigers. The new species of Oligobregma has large acicular spines in both noto- and neuropodia and these are present in juveniles. However, the final adult configuration of the prostomium is not evident until late in development. The taxonomic significance of the timing of development of post-larval and juvenile morphology elucidated in this study is discussed in relation to the validity of certain taxa and the current system of genera used in the family. PMID:26624392

  5. Biochemical compounds' dynamics during larval development of the carpet-shell clam Ruditapes decussatus (Linnaeus, 1758): effects of mono-specific diets and starvation

    NASA Astrophysics Data System (ADS)

    Matias, Domitília; Joaquim, Sandra; Ramos, Margarete; Sobral, Paula; Leitão, Alexandra

    2011-09-01

    Successful larval growth and development of bivalves depend on energy derived from internal (endotrophic phase) and external (exotrophic phase) sources. The present paper studies survival, growth and biochemical changes in the early developmental stages (from egg to pediveliger) of the clam Ruditapes decussatus in order to characterize the nutritional requirements and the transition from the endotrophic to the exotrophic phase. Three different feeding regimes were applied: starvation and two mono-specific microalgal diets ( Isochrysis aff galbana and Chaetoceros calcitrans). A comparison between fed and unfed larvae highlighted the importance of egg lipid reserves, especially neutral lipids, during a brief endotrophic phase of embryonic development (first 2 days after fertilization). Egg reserves, however, may energetically contribute to the maintenance of larvae beyond the embryonic development. In fed larvae, the endotrophic phase is followed by a mixotrophic phase extending to days 5-8 after fertilization and a subsequent exotrophic phase. Metamorphosis starts around day 20. The intense embryonic activities are supported by energy derived from lipids, mainly from neutral lipids, and the metamorphic activities are supported by energy derived essentially from proteins accumulated during the planktonic phase and depend on the nutritional value of diets. The diet of I. aff galbana proves to be more adequate to R. decussatus larval rearing. The results provide useful information for the successful production of R. decussatus aquaculture.

  6. Origin and development of neuropil glia of the Drosophila larval and adult brain: two distinct glial populations derived from separate progenitors

    PubMed Central

    Omoto, Jaison Jiro; Yogi, Puja; Hartenstein, Volker

    2015-01-01

    Glia comprise a conspicuous population of non-neuronal cells in vertebrate and invertebrate nervous systems. Drosophila serves as a favorable model to elucidate basic principles of glial biology in vivo. The Drosophila neuropil glia (NPG), subdivided into astrocyte-like (ALG) and ensheathing glia (EG), extend reticular processes which associate with synapses and sheath-like processes which surround neuropil compartments, respectively. In this paper we characterize the development of NPG throughout fly brain development. We find that differentiated neuropil glia of the larval brain originate as a cluster of precursors derived from embryonic progenitors located in the basal brain. These precursors undergo a characteristic migration to spread over the neuropil surface while specifying/differentiating into primary ALG and EG. Embryonically-derived primary NPG are large cells which are few in number, and occupy relatively stereotyped positions around the larval neuropil surface. During metamorphosis, primary NPG undergo cell death. Neuropil glia of the adult (secondary NPG) are derived from type II lineages during the postembryonic phase of neurogliogenesis. These secondary NPG are much smaller in size but greater in number than primary NPG. Lineage tracing reveals that both NPG subtypes derive from intermediate neural progenitors of multipotent type II lineages. Taken together, this study reveals previously uncharacterized dynamics of NPG development and provides a framework for future studies utilizing Drosophila glia as a model. PMID:25779704

  7. Origin and development of neuropil glia of the Drosophila larval and adult brain: Two distinct glial populations derived from separate progenitors.

    PubMed

    Omoto, Jaison Jiro; Yogi, Puja; Hartenstein, Volker

    2015-08-15

    Glia comprise a conspicuous population of non-neuronal cells in vertebrate and invertebrate nervous systems. Drosophila serves as a favorable model to elucidate basic principles of glial biology in vivo. The Drosophila neuropil glia (NPG), subdivided into astrocyte-like (ALG) and ensheathing glia (EG), extend reticular processes which associate with synapses and sheath-like processes which surround neuropil compartments, respectively. In this paper we characterize the development of NPG throughout fly brain development. We find that differentiated neuropil glia of the larval brain originate as a cluster of precursors derived from embryonic progenitors located in the basal brain. These precursors undergo a characteristic migration to spread over the neuropil surface while specifying/differentiating into primary ALG and EG. Embryonically-derived primary NPG are large cells which are few in number, and occupy relatively stereotyped positions around the larval neuropil surface. During metamorphosis, primary NPG undergo cell death. Neuropil glia of the adult (secondary NPG) are derived from type II lineages during the postembryonic phase of neurogliogenesis. These secondary NPG are much smaller in size but greater in number than primary NPG. Lineage tracing reveals that both NPG subtypes derive from intermediate neural progenitors of multipotent type II lineages. Taken together, this study reveals previously uncharacterized dynamics of NPG development and provides a framework for future studies utilizing Drosophila glia as a model. PMID:25779704

  8. Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.

    PubMed

    Heyes, Andrew; Rowe, Christopher L; Conrad, Phillip

    2014-01-01

    We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements. PMID:24169791

  9. Milt characteristics, reproductive performance, and larval survival and development of white sucker exposed to bleached kraft mill effluent

    SciTech Connect

    McMaster, M.E.; Portt, C.B.; Munkittrick, K.R.; Dixon, D.G. )

    1992-02-01

    White sucker from a Lake Superior bay which receives bleached kraft mill effluent (BKME) show increased hepatic mixed-function oxygenase (MFO) activity, reduced plasma sex steroid levels, decreased egg and gonad size, a decrease in the occurrence of secondary sexual characteristics, and an increased age to maturation. This study evaluated the reproductive performance of that white sucker population relative to a similar reference population. Spawning male white sucker from the BKME site had reduced spermatozoan motility but no significant differences in milt volume, spermatocrit levels, or seminal plasma constituents. BKME male and female fish had equal or greater fertilization potential compared to both male and female fish at the reference site. There was no difference either in the hatchability of the eggs or in larval size at hatch. BKME larvae did show reduced growth rates by 24 days posthatch but showed equal rates of yolk utilization. No difference in larval MFO activity was detected between sites at 21 days posthatch, indicating no parental transfer of induction to the progeny.

  10. Embryonic and Larval Development and Early Behavior in Grass Carp, Ctenopharyngodon idella: Implications for Recruitment in Rivers

    PubMed Central

    George, Amy E.; Chapman, Duane C.

    2015-01-01

    With recent findings of grass carp Ctenopharyngodon idella in tributaries of the Great Lakes, information on developmental rate and larval behavior is critical to efforts to assess the potential for establishment within the tributaries of that region. In laboratory experiments, grass carp were spawned and eggs and larvae reared at two temperature treatments, one “cold” and one “warm”, and tracked for developmental rate, egg size, and behavior. Developmental rate was quantified using Yi’s (1988) developmental stages and the cumulative thermal units method. Grass carp had a thermal minimum of 13.5°C for embryonic stages and 13.3°C for larval stages. Egg size was related to temperature and maternal size, with the largest eggs coming from the largest females, and eggs were generally larger in warmer treatments. Young grass carp larvae exhibited upward and downward swimming interspersed with long periods of lying on the bottom. Swimming capacity increased with ontogeny, and larvae were capable of horizontal swimming and position holding with gas bladder emergence. Developmental rates, behavior, and egg attributes can be used in combination with physical parameters of a river to assess the risk that grass carp are capable of reproduction and recruitment in rivers. PMID:25822837

  11. Embryonic and larval development and early behavior in grass carp, Ctenopharyngodon idella: implications for recruitment in rivers

    USGS Publications Warehouse

    George, Amy E.; Chapman, Duane C.

    2015-01-01

    With recent findings of grass carp Ctenopharyngodon idella in tributaries of the Great Lakes, information on developmental rate and larval behavior is critical to efforts to assess the potential for establishment within the tributaries of that region. In laboratory experiments, grass carp were spawned and eggs and larvae reared at two temperature treatments, one "cold" and one "warm", and tracked for developmental rate, egg size, and behavior. Developmental rate was quantified using Yi's (1988) developmental stages and the cumulative thermal units method. Grass carp had a thermal minimum of 13.5°C for embryonic stages and 13.3°C for larval stages. Egg size was related to temperature and maternal size, with the largest eggs coming from the largest females, and eggs were generally larger in warmer treatments. Young grass carp larvae exhibited upward and downward swimming interspersed with long periods of lying on the bottom. Swimming capacity increased with ontogeny, and larvae were capable of horizontal swimming and position holding with gas bladder emergence. Developmental rates, behavior, and egg attributes can be used in combination with physical parameters of a river to assess the risk that grass carp are capable of reproduction and recruitment in rivers.

  12. Nitric Oxide Affects ERK Signaling through Down-Regulation of MAP Kinase Phosphatase Levels during Larval Development of the Ascidian Ciona intestinalis

    PubMed Central

    Palumbo, Anna

    2014-01-01

    In the ascidian Ciona intestinalis larval development and metamorphosis require a complex interplay of events, including nitric oxide (NO) production, MAP kinases (ERK, JNK) and caspase-3 activation. We have previously shown that NO levels affect the rate of metamorphosis, regulate caspase activity and promote an oxidative stress pathway, resulting in protein nitration. Here, we report that NO down-regulates MAP kinase phosphatases (mkps) expression affecting positively ERK signaling. By pharmacological approach, we observed that the reduction of endogenous NO levels caused a decrease of ERK phosphorylation, whereas increasing levels of NO induced ERK activation. We have also identified the ERK gene network affected by NO, including mpk1, mpk3 and some key developmental genes by quantitative gene expression analysis. We demonstrate that NO induces an ERK-independent down-regulation of mkp1 and mkp3, responsible for maintaining the ERK phosphorylation levels necessary for transcription of key metamorphic genes, such as the hormone receptor rev-erb and the van willebrand protein vwa1c. These results add new insights into the role played by NO during larval development and metamorphosis in Ciona, highlighting the cross-talk between different signaling pathways. PMID:25058405

  13. Identification and quantification of hydroxamic acids in maize seedling root tissue and impact on western corn rootworm (Coleoptera: Chrysomelidae) larval development.

    PubMed

    Davis, C S; Ni, X; Quisenberry, S S; Foster, J E

    2000-06-01

    Hydroxamic acid content was analyzed in the root tissue of four maize, Zea mays L., lines using high-performance liquid chromatography (HPLC) and related to western corn rootworm, Diabrotica virgifera virgifera LeConte, larval development and survivorship. Maize lines evaluated included Mp710 (PI 596627), MpSWCB-4, (PI 550498), Sc213 (PI 548792), and Dk580 (DeKalb commercial hybrid). Maize plants from each line were grown in test tubes containing a transparent agarose gel medium in a growth chamber. After 8 d of growth, root tissue of each line was harvested and hydroxamic acid content analyzed using HPLC. Three hydroxamic acids, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 6-methoxybenzoxazolinone (MBOA), and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), were identified in the maize roots tested. DIMBOA concentration was quantified and ranged from 246.37 +/- 70.53 micrograms to 91.84 +/- 49.82 micrograms DIMBOA per gram of root tissue. No significant difference was found among lines in D. v. virgifera larval development and survivorship. PMID:10902360

  14. Environmental concentrations of the cocaine metabolite benzoylecgonine induced sublethal toxicity in the development of plants but not in a zebrafish embryo-larval model.

    PubMed

    García-Cambero, J P; García-Cortés, H; Valcárcel, Y; Catalá, M

    2015-12-30

    Several studies have found cocaine and its main active metabolite benzoylecgonine (BE) in the aquatic environment and drinking water, derived from its consumption by humans as well as the inability of water treatment processes to eliminate it. A few studies have already investigated the ecotoxicology of BE to aquatic invertebrates, but none has still addressed the effects of BE on aquatic vertebrates or vascular plants. The goal of this publication is to provide information on the toxicity of environmental concentrations of BE during animal and vascular plant development, in order to contribute to a better understanding of the potential risk of this substance for the environment. BE induced alterations in mitochondrial activity and DNA levels of fern spores at environmental concentrations (1 ng L(-1)), which could disrupt gametophyte germination. However, BE at concentrations ranging from 1 ng L(-1) to 1 mg L(-1) did not disturb morphogenesis, hatching, heartbeat rate or larval motility in a zebrafish embryo-larval model. Adverse effects on ferns agree with the allelophathic role described for alkaloids and their unspecific interference with plant germination. Therefore, the anthropogenic dispersion of alkaloid allelochemicals may pose a risk for biodiversity and irrigated food production that should be further investigated. PMID:26340554

  15. Influence of salinity on the larval development of the fiddler crab Uca vocator (Ocypodidae) as an indicator of ontogenetic migration towards offshore waters

    NASA Astrophysics Data System (ADS)

    de Jesus de Brito Simith, Darlan; de Souza, Adelson Silva; Maciel, Cristiana Ramalho; Abrunhosa, Fernando Araújo; Diele, Karen

    2012-03-01

    Larvae of many marine decapod crustaceans are released in unpredictable habitats with strong salinity fluctuations during the breeding season. In an experimental laboratory study, we investigated the influence of seven different salinities (0, 5, 10, 15, 20, 25 and 30) on the survival and development time of fiddler crab zoea larvae, Uca vocator, from northern Brazilian mangroves. The species reproduces during the rainy season when estuarine salinity strongly fluctuates and often reaches values below 10 and even 5. Salinity significantly affected the survival rate and development period from hatching to megalopa, while the number of zoeal stages remained constant. In salinities 0 and 5, no larvae reached the second zoeal stage, but they managed to survive for up to 3 (average of 2.3 days) and 7 days (average of 5.1 days), respectively. From salinity 10 onwards, the larvae developed to the megalopal stage. However, the survival rate was significantly lower (5-15%) and development took more time (average of 13.5 days) in salinity 10 than in the remaining salinities (15-30). In the latter, survival ranged from 80-95% and development took 10-11 days. Given the 100% larval mortality in extremely low salinities and their increased survival in intermediate and higher salinities, we conclude that U. vocator has a larval `export' strategy with its larvae developing in offshore waters where salinity conditions are more stable and higher than in mangrove estuaries. Thus, by means of ontogenetic migration, osmotic stress and resulting mortality in estuarine waters can be avoided.

  16. Effects of ambient temperature on egg and larval development of the invasive emerald ash borer (Coleoptera: Buprestidae): implications for laboratory rearing.

    PubMed

    Duan, Jian J; Watt, Tim; Taylor, Phil; Larson, Kristi; Lelito, Jonathan P

    2013-10-01

    The emerald ash borer, Agrilus planipennis Fairmaire, an invasive beetle from Asia causing large scale ash (Fraxinus) mortality in North America, has been extremely difficult to rear in the laboratory because of its long life cycle and cryptic nature of immature stages. This lack of effective laboratory-rearing methods has not only hindered research into its biology and ecology, but also mass production of natural enemies for biological control of this invasive pest. Using sticks from the alternate host plant, Fraxinus uhdei (Wenzig) Lingelsh, we characterized the stage-specific development time and growth rate of both emerald ash borer eggs and larvae at different constant temperatures (12-35 degrees C) for the purpose of developing effective laboratory-rearing methods. Results from our study showed that the median time for egg hatching decreased from 20 d at 20 degrees C to 7 d at 35 degrees C, while no emerald ash borer eggs hatched at 12 degrees C. The developmental time for 50% of emerald ash borer larvae advancing to third, fourth, and J-larval stages at 20 degrees C were 8.3, 9.1, and 12.3 wk, respectively, approximately two times longer than at 30 degrees C for the corresponding instars or stages. In contrast to 30 degrees C, however, the development times of emerald ash borer larvae advancing to later instars (from oviposition) were significantly increased at 35 degrees C, indicating adverse effects of this high temperature. The optimal range of ambient temperature to rear emerald ash borer larvae should be between 25-30 degrees C; however, faster rate of egg and larval development should be expected as temperature increases within this range. PMID:24224252

  17. Life History, Reproductive Biology, and Larval Development of Ontsira mellipes (Hymenoptera: Braconidae), a Newly Associated Parasitoid of the Invasive Asian Longhorned Beetle (Coleoptera: Cerambycidae).

    PubMed

    Golec, Julian R; Duan, Jian J; Aparicio, Ellen; Hough-Goldstein, Judith

    2016-08-01

    The invasive Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), is a destructive xylophagous forest pest species originating from Asia. Several endemic North American hymenopteran (Braconidae) species in the mid-Atlantic region were capable of attacking and reproducing on A. glabripennis larvae in laboratory bioassays. Ontsira mellipes Ashmead (Hymenoptera: Braconidae) has been continually reared on A. glabripennis larvae at USDA-ARS BIIRU since 2010, and has been identified as a potential new-association biocontrol agent. Two experiments were conducted to investigate parasitism, paralysis, reproductive biology, larval development, and longevity of adult O. mellipes In the first experiment, pairs of adult parasitoids were given single A. glabripennis larvae every 2 d (along with honey and water) over their lifetimes, while in the second experiment individual parasitoids were observed daily from egg to adult, and adults were subsequently starved. Adults in the first experiment parasitized ∼21% of beetle larvae presented to them throughout their life, and paralysis of larvae occurred 1-2 d after oviposition. More than half of the individual pairs parasitized A. glabripennis larvae, with each female producing around 26 offspring throughout her life. In the second experiment, median development time of O. mellipes from egg to adult was about 3 wk, with five larval instars. Adult O. mellipes that were provided with host larvae, honey, and water lived 9 d longer than host-deprived and starved adults. These findings indicate that mass-rearing procedures for O. mellipes may be developed using the new association host for development of effective biocontrol programs against A. glabripennis. PMID:27329634

  18. Soundscapes and Larval Settlement: Characterizing the Stimulus from a Larval Perspective.

    PubMed

    Lillis, Ashlee; Eggleston, David B; Bohnenstiehl, DelWayne R

    2016-01-01

    There is growing evidence that underwater sounds serve as a cue for the larvae of marine organisms to locate suitable settlement habitats; however, the relevant spatiotemporal scales of variability in habitat-related sounds and how this variation scales with larval settlement processes remain largely uncharacterized, particularly in estuarine habitats. Here, we provide an overview of the approaches we have developed to characterize an estuarine soundscape as it relates to larval processes, and a conceptual framework is provided for how habitat-related sounds may influence larval settlement, using oyster reef soundscapes as an example. PMID:26611014

  19. bHLH-PAS family transcription factor methoprene-tolerant plays a key role in JH action in preventing the premature development of adult structures during larval-pupal metamorphosis

    PubMed Central

    Parthasarathy, R.; Tan, Anjiang; Palli, Subba R.

    2008-01-01

    The biological actions of juvenile hormones are well studied; they regulate almost all aspects of an insect’s life. However, the molecular actions of these hormones are not well understood. Recent studies in the red flour beetle, Tribolium castaneum, demonstrated the utility of this insect as a model system to study JH action. These studies confirmed that the bHLH-PAS family transcription factor, methoprene-tolerant (TcMet,) plays a key role in JH action during larval stages. In this study, we investigated the role of TcMet in JH action during larval-pupal metamorphosis. The phenotypes of TcMet RNAi insects shared similarity with the phenotypes of some allatectomized lepidopteran larvae that were attempting to undergo precocious larval-pupal metamorphosis. Knocking-down TcMet during the final instar also disrupted larval-pupal ecdysis, resulting in the development of adultoid underneath the larval skin. However, the loss of TcMet did not completely block remodeling of internal tissues such as midgut. T. castaneum larvae injected with TcMet dsRNA demonstrated a resistance to a JH analog (JHA), hydroprene, irrespective of time and route of application. Knocking-down TcMet also caused down regulation of JH-response genes, JHE and Kr-h1 suggesting that TcMet might be involved in the expression of these genes. Based on the phenotype, gene expression, and JHA action studies in TcMet RNAi insects, this study concludes that Met plays a key role in JH action for preventing the premature development of adult structures during larval-pupal metamorphosis. PMID:18450431

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

    PubMed

    Espinoza, I; Galindo, M; Bizarro, C V; Ferreira, H B; Zaha, A; Galanti, N

    2005-11-01

    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. PMID:15887242

  1. The Drosophila melanogaster importin alpha3 locus encodes an essential gene required for the development of both larval and adult tissues.

    PubMed Central

    Mason, D Adam; Máthé, Endre; Fleming, Robert J; Goldfarb, David S

    2003-01-01

    The nuclear transport of classical nuclear localization signal (cNLS)-containing proteins is mediated by the cNLS receptor importin alpha. The conventional importin alpha gene family in metazoan animals is composed of three clades that are conserved between flies and mammals and are referred to here as alpha1, alpha2, and alpha3. In contrast, plants and fungi contain only alpha1 genes. In this study we report that Drosophila importin alpha3 is required for the development of both larval and adult tissues. Importin alpha3 mutant flies die around the transition from first to second instar larvae, and homozygous importin alpha3 mutant eyes are defective. The transition to second instar larvae was rescued with importin alpha1, alpha2, or alpha3 transgenes, indicating that Importin alpha3 is normally required at this stage for an activity shared by all three importin alpha's. In contrast, an alpha3-specific biochemical activity(s) of Importin alpha3 is probably required for development to adults and photoreceptor cell development, since only an importin alpha3 transgene rescued these processes. These results are consistent with the view that the importin alpha's have both overlapping and distinct functions and that their role in animal development involves the spatial and temporal control of their expression. PMID:14704178

  2. Genome-wide identification and characterization of long intergenic noncoding RNAs and their potential association with larval development in the Pacific oyster

    PubMed Central

    Yu, Hong; Zhao, Xuelin; Li, Qi

    2016-01-01

    An increasing amount of evidence suggests that long intergenic noncoding RNAs (lincRNAs) may play diverse roles in many cellular processes. However, little is known about lincRNAs in marine invertebrates. Here, we presented the first identification and characterization of lincRNAs in the Pacific oyster (Crassostrea gigas). We developed a pipeline and identified 11,668 lincRNAs in C. gigas based on RNA-Seq resources available. These lincRNAs exhibited many common characteristics with vertebrate lincRNAs: relatively short length, low exon numbers, low expression, and low sequence conservation. 1,175 lincRNAs were expressed in a tissue-specific manner, with 35.2% preferentially expressed in male gonad. 776 lincRNAs were specifically expressed in juvenile during different developmental stages. In addition, 47 lincRNAs were found to be potentially related to oyster settlement and metamorphosis. Such diverse temporal and spatial patterns of expression suggest that these lincRNAs might function in cell differentiation during early development, as well as sex differentiation and reproduction. Based on a co-expression network analysis, five lincRNAs were detected that have an expression correlation with key hub genes in four modules significantly correlated with larval development. Our study provides the first large-scale identification of lincRNAs in molluscs and offers new insights into potential functions of lincRNAs in marine invertebrates. PMID:26861843

  3. Genome-wide identification and characterization of long intergenic noncoding RNAs and their potential association with larval development in the Pacific oyster.

    PubMed

    Yu, Hong; Zhao, Xuelin; Li, Qi

    2016-01-01

    An increasing amount of evidence suggests that long intergenic noncoding RNAs (lincRNAs) may play diverse roles in many cellular processes. However, little is known about lincRNAs in marine invertebrates. Here, we presented the first identification and characterization of lincRNAs in the Pacific oyster (Crassostrea gigas). We developed a pipeline and identified 11,668 lincRNAs in C. gigas based on RNA-Seq resources available. These lincRNAs exhibited many common characteristics with vertebrate lincRNAs: relatively short length, low exon numbers, low expression, and low sequence conservation. 1,175 lincRNAs were expressed in a tissue-specific manner, with 35.2% preferentially expressed in male gonad. 776 lincRNAs were specifically expressed in juvenile during different developmental stages. In addition, 47 lincRNAs were found to be potentially related to oyster settlement and metamorphosis. Such diverse temporal and spatial patterns of expression suggest that these lincRNAs might function in cell differentiation during early development, as well as sex differentiation and reproduction. Based on a co-expression network analysis, five lincRNAs were detected that have an expression correlation with key hub genes in four modules significantly correlated with larval development. Our study provides the first large-scale identification of lincRNAs in molluscs and offers new insights into potential functions of lincRNAs in marine invertebrates. PMID:26861843

  4. Larval development of the pedunculate barnacles Octolasmis angulata Aurivillius 1894 and Octolasmis cor Aurivillius 1892 (Cirripedia: Thoracica: Poecilasmatidae) from the gills of the mud crab, Scylla tranquebarica Fabricius, 1798.

    PubMed

    Yap, F C; Wong, W L; Maule, A G; Brennan, G P; Lim, L H S

    2015-05-01

    Detailed studies of larval development of Octolasmis angulata and Octolasmis cor are pivotal in understanding the larval morphological evolution as well as enhancing the functional ecology. Six planktotrophic naupliar stages and one non-feeding cyprid stage are documented in details for the first time for the two species of Octolasmis. Morphologically, the larvae of O. angulata and O. cor are similar in body size, setation patterns on the naupliar appendages, labrum, dorsal setae-pores, frontal horns, cyprid carapace, fronto-lateral gland pores, and lattice organs. Numbers of peculiarities were observed on the gnathobases of the antennae and mandible throughout the naupliar life-cycle. The setation pattern on the naupliar appendages are classified based on the segmentation on the naupliar appendages. The nauplius VI of both species undergoes a conspicuous change before metamorphosis into cyprid stage. The cyprid structures begin to form and modify beneath the naupliar body towards the end of stage VI. This study emphasises the importance of the pedunculate barnacle larval developmental studies not only to comprehend the larval morphological evolution but also to fill in the gaps in understanding the modification of the naupliar structures to adapt into the cyprid life-style. PMID:25770075

  5. Measuring thigmotaxis in larval zebrafish.

    PubMed

    Schnörr, S J; Steenbergen, P J; Richardson, M K; Champagne, D L

    2012-03-17

    One of the most commonly used behavioral endpoints measured in preclinical studies using rodent models is thigmotaxis (or "wall-hugging"). Thigmotaxis is a well-validated index of anxiety in animals and humans. While assays measuring thigmotaxis in adult zebrafish have been developed, a thigmotaxis assay has not yet been validated in larval zebrafish. Here we present a novel assay for measurement of thigmotaxis in zebrafish larvae that is triggered by a sudden change in illumination (i.e. sudden light-to-darkness transition) and performed in a standard 24-well plate. We show that zebrafish larvae as young as 5 days post fertilization respond to this challenge by engaging in thigmotaxis. Thigmotaxis was significantly attenuated by anxiolytic (diazepam) and significantly enhanced by anxiogenic (caffeine) drugs, thus representing the first validated thigmotaxis assay for larval zebrafish. We also show that exposure to sudden darkness per se may represent an anxiogenic situation for larval zebrafish since less contrasting light-to-darkness transitions (achieved by lowering darkness degrees) significantly decreased thigmotaxis levels in a manner similar to what was achieved with diazepam. These findings suggest that stimuli such as exposure to sudden darkness could be used proficiently to trigger the expression of anxiety-like behaviors in laboratory settings. In sum, this is a versatile protocol allowing testing of both anxiolytic and anxiogenic drugs in a cost-effective manner (only 10 min). This assay is also amenable to medium to high-throughput capacity while constituting a valuable tool for stress and central nervous system research as well as for preclinical drug screening and discovery. PMID:22197677

  6. The effect of silencing 20E biosynthesis relative genes by feeding bacterially expressed dsRNA on the larval development of Chilo suppressalis.

    PubMed

    Zhu, Jian; Dong, Yong-Cheng; Li, Ping; Niu, Chang-Ying

    2016-01-01

    RNA interference (RNAi) is a robust tool to study gene functions as well as potential for insect pest control. Finding suitable target genes is the key step in the development of an efficient RNAi-mediated pest control technique. Based on the transcriptome of Chilo suppressalis, 24 unigenes which putatively associated with insect hormone biosynthesis were identified. Amongst these, four genes involved in ecdysteroidogenesis i.e., ptth, torso, spook and nm-g were evaluated as candidate targets for function study. The partial cDNA of these four genes were cloned and their bacterially expressed dsRNA were fed to the insects. Results revealed a significant reduction in mRNA abundance of target genes after 3 days. Furthermore, knocked down of these four genes resulted in abnormal phenotypes and high larval mortality. After 15 days, the survival rates of insects in dsspook, dsptth, dstorso, and dsnm-g groups were significantly reduced by 32%, 38%, 56%, and 67% respectively, compared with control. Moreover, about 80% of surviving larvae showed retarded development in dsRNA-treated groups. These results suggest that oral ingestion of bacterially expressed dsRNA in C. suppressalis could silence ptth, torso, spook and nm-g. Oral delivery of bacterially expressed dsRNA provides a simple and potential management scheme against C. suppressalis. PMID:27352880

  7. The effect of silencing 20E biosynthesis relative genes by feeding bacterially expressed dsRNA on the larval development of Chilo suppressalis

    PubMed Central

    Zhu, Jian; Dong, Yong-Cheng; Li, Ping; Niu, Chang-Ying

    2016-01-01

    RNA interference (RNAi) is a robust tool to study gene functions as well as potential for insect pest control. Finding suitable target genes is the key step in the development of an efficient RNAi-mediated pest control technique. Based on the transcriptome of Chilo suppressalis, 24 unigenes which putatively associated with insect hormone biosynthesis were identified. Amongst these, four genes involved in ecdysteroidogenesis i.e., ptth, torso, spook and nm-g were evaluated as candidate targets for function study. The partial cDNA of these four genes were cloned and their bacterially expressed dsRNA were fed to the insects. Results revealed a significant reduction in mRNA abundance of target genes after 3 days. Furthermore, knocked down of these four genes resulted in abnormal phenotypes and high larval mortality. After 15 days, the survival rates of insects in dsspook, dsptth, dstorso, and dsnm-g groups were significantly reduced by 32%, 38%, 56%, and 67% respectively, compared with control. Moreover, about 80% of surviving larvae showed retarded development in dsRNA-treated groups. These results suggest that oral ingestion of bacterially expressed dsRNA in C. suppressalis could silence ptth, torso, spook and nm-g. Oral delivery of bacterially expressed dsRNA provides a simple and potential management scheme against C. suppressalis. PMID:27352880

  8. Influence of metal(loid) bioaccumulation and maternal transfer on embryo-larval development in fish exposed to a major coal ash spill

    DOE PAGESBeta

    Greeley, Jr., Mark Stephen; Adams, S. Marshall; Elmore, Logan R.; McCracken, Mary Kitty

    2016-01-03

    In December 2008, an earthen retaining wall at the Tennessee Valley Authority (TVA) Kingston Fossil Fuel Plant failed and released 4.1 million m3 of coal ash to rivers flowing into Watts Bar Reservoir in east Tennessee, United States (U.S.). As part of a comprehensive effort to evaluate the risks to aquatic resources from this spill – the largest in U.S. history – we compared bioaccumulation and maternal transfer of selenium (Se), arsenic (As), and mercury (Hg) in adult redear sunfish (Lepomis macrolophus), collected two years after the spill from both coal-ash exposed and non-exposed areas of the Emory and Clinchmore » Rivers, with the success of embryo-larval development in their offspring. Whole body and ovary concentrations of Se in female sunfish at three study sites downstream of the spill were significantly elevated (site means = 4.9–5.3 and 6.7–9.0 mg/kg d.w. whole body and ovary concentrations, respectively) compared with concentrations in fish from reference sites upstream of the spill site (2.2–3.2 mg/kg d.w. for whole bodies and 3.6–4.8 mg/kg d.w. for ovaries). However, Se concentrations in coal ash-exposed areas remain below proposed U.S. Environmental Protection Agency (USEPA) criteria for the protection of aquatic life. Site-to-site variation in fish concentrations of As and Hg were not well-correlated with ash-exposure, reflecting the multiple sources of these metal(loid)s in the affected watersheds. In 7-day laboratory tests of embryos and larvae derived from in vitro crosses of eggs and sperm from these field-collected sunfish, fertilization success, hatching success, embryo-larval survival, and incidences of developmental abnormalities did not differ significantly between ash-exposed and non-exposed fish. Furthermore, these developmental endpoints were not correlated with whole body or ovary concentrations of Se, As, or Hg in the maternal fish, or with fish size, ovary weight, or gonadal-somatic indices. Furthermore, results from

  9. Influence of metal(loid) bioaccumulation and maternal transfer on embryo-larval development in fish exposed to a major coal ash spill.

    PubMed

    Greeley, Mark S; Adams, S Marshall; Elmore, Logan R; McCracken, Mary K

    2016-04-01

    In December 2008, an earthen retaining wall at the Tennessee Valley Authority (TVA) Kingston Fossil Fuel Plant failed and released 4.1 millionm(3) of coal ash to rivers flowing into Watts Bar Reservoir in east Tennessee, United States (U.S.). As part of a comprehensive effort to evaluate the risks to aquatic resources from this spill - the largest in U.S. history - we compared bioaccumulation and maternal transfer of selenium (Se), arsenic (As), and mercury (Hg) in adult redear sunfish (Lepomis macrolophus), collected two years after the spill from both coal-ash exposed and non-exposed areas of the Emory and Clinch Rivers, with the success of embryo-larval development in their offspring. Whole body and ovary concentrations of Se in female sunfish at three study sites downstream of the spill were significantly elevated (site means=4.9-5.3 and 6.7-9.0mg/kg d.w. whole body and ovary concentrations, respectively) compared with concentrations in fish from reference sites upstream of the spill site (2.2-3.2mg/kg d.w. for whole bodies and 3.6-4.8mg/kg d.w. for ovaries). However, Se concentrations in coal ash-exposed areas remain below proposed U.S. Environmental Protection Agency (USEPA) criteria for the protection of aquatic life. Site-to-site variation in fish concentrations of As and Hg were not well-correlated with ash-exposure, reflecting the multiple sources of these metal(loid)s in the affected watersheds. In 7-day laboratory tests of embryos and larvae derived from in vitro crosses of eggs and sperm from these field-collected sunfish, fertilization success, hatching success, embryo-larval survival, and incidences of developmental abnormalities did not differ significantly between ash-exposed and non-exposed fish. Furthermore, these developmental endpoints were not correlated with whole body or ovary concentrations of Se, As, or Hg in the maternal fish, or with fish size, ovary weight, or gonadal-somatic indices. Results from this and related studies associated

  10. Protective immune responses of the jird to larval Dipetalonema viteae.

    PubMed Central

    Abraham, D; Weiner, D J; Farrell, J P

    1986-01-01

    In vivo and in vitro experiments were performed to study immune protective mechanisms against larval Dipetalonema viteae. Jirds infected with 30 third-stage larvae (L3) of D. viteae for 1, 3 or 5 weeks showed significant killing of challenge larvae implanted for 2 weeks in diffusion chambers. A retardation of larval growth was seen 7 days after larval implantation, and larval death was observed beginning at 10 days. When L3 were placed in vitro with peritoneal exudate cells (PEC) from normal jirds, cellular adherence was seen starting on Day 4, and larval death was seen on Day 10. It was concluded that larvae had to undergo some development in vitro, that would allow cellular adherence to larval surface. Larvae, recovered after 7 days in vivo or in vitro, were placed in culture with normal PEC; cell adherence and worm death occurred at equal rates for both groups of worms. Larvae which had been in culture for 7 days were implanted in immunized jirds for 7 days. Significant killing of these worms was observed, whereas larvae recovered from ticks prior to implantation were not killed. In vivo and in vitro results therefore show that larval development is required for generating susceptibility to specific and/or non-specific immune reactions. A hypothesis is suggested for the function of larval retardation. PMID:3943876

  11. Laboratory evaluation of novaluron as a development site treatment for controlling larval horn flies, house flies, and stable flies (Diptera: Muscidae).

    PubMed

    Lohmeyer, K H; Pound, J M

    2012-05-01

    A granular formulation of novaluron (Novaluron 0.2G, 0.2% [AI]), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.); house flies, Musca domestica L.; and stable flies, Stomoxys calcitrans (L.), in cow manure. Various rates and insecticide placement locations (top, middle, and bottom of manure) were evaluated in this study and all combinations of these variables reduced adult emergence of all three species when compared with the untreated controls. The presence of deformed pupae indicated that novaluron had an insect growth regulator effect on the developing fly larvae. Top, middle, or bottom application rates of 0.125, 0.195, 0.25, and 0.375 g novaluron onto manure samples, reduced adult horn fly emergence by > 90%. Middle and bottom application rates of 0.195, 0.25, and 0.375 g novaluron reduced adult house fly emergence >93%. All rates and placement combinations resulted in >98% reduction of adult stable fly emergence. The level of control efficacy observed against these three fly species along with the ease of use of a granular formulation, make this product an ideal candidate for use in an integrated livestock pest management program. PMID:22679873

  12. A new case of poecilogony from South America and the implications of nurse eggs, capsule structure, and maternal brooding behavior on the development of different larval types.

    PubMed

    Oyarzun, Fernanda X; Brante, Antonio

    2015-04-01

    Poecilogony is the production of different larval types within the same species. Although rare, poecilogonous species are ideal systems for testing the evolutionary and ecological implication of different developmental modes in marine invertebrates. Here, we described a new case of poecilogony, the Southern Hemisphere spionid Boccardia wellingtonensis. We used a combination of common-garden experiments, video recordings, and in vitro manipulations of individuals from three sites to (1) document the type of poecilogony, the brooding behavior of the mother, and the hatching process; (2) experimentally measure the effect of nurse eggs on the growth and type of larvae produced; and (3) document variation in the length of the brooding period, number of capsules, larvae, and nurse eggs of mothers from three sites to explore the potential for plasticity in reproductive traits. These results were compared to the previously reported poecilogonous species B. proboscidea, which resembles B. wellingtonensis in size, morphology, ecology, and reproductive strategy but differs in capsule structure. We found that in contrast to B. proboscidea, B. wellingtonensis produced larvae that, in isolation and in the presence of nurse eggs, developed into a wide range of offspring sizes. Mothers brood and hatch the larvae with frequent partial hatching of the brood during the brooding period. Although larvae could not liberate themselves, larvae crossed to other capsules as interconnections between capsules broke during the developmental period, potentially affecting food availability, sibling competition for nurse eggs, and cannibalism. Variation in brooding time and number of capsules deposited among sites suggest local adaptations. PMID:25920712

  13. Ontogeny and distribution of cholecystokinin-immuno reactive cells in the digestive tract of sharpsnout sea bream, Diplodus puntazzo (Cetti, 1777), during larval development.

    PubMed

    Micale, Valeria; Levanti, Maria Beatrice; Germanà, Antonino; Guerrera, Maria Cristina; Kurokawa, Tadahide; Muglia, Ugo

    2010-10-01

    The appearance and regional distribution of cholecystokinin-immuno reactive cells (CCK-IR) in the developing gut of larval Diplodus puntazzo were studied by means of immunohistochemistry, with the aim of understanding the role of this peptide hormone in the acquisition of digestive capacity. Immunohistochemical reaction showed CCK-IR cells from 10 days after hatching (DAH), near the pyloric sphincter and past the first bend in the midgut, as well as in the hindgut. At 25 DAH CCK-IR cells were scattered throughout the midgut, as well as in the hindgut. Since gastric glands appeared at 30 DAH, CCK-IR cells were most abundant in the anterior midgut, near and including the pyloric caeca, and just afore the ileo-rectal sphincter in the posterior midgut, as well as in the hindgut. In older larvae (39 DAH), CCK-IR cells were mainly distributed in the anterior midgut, including the pyloric caeca, as well as in the hindgut. No CCK-IR cells were detected in the foregut at any stage. The distribution pattern of CCK-IR cells differed from other species which also possess a rotated gut as D. puntazzo. In fact, although cells were abundant in regions where the ingested food is retained, so that they can be stimulated to modulating the release of digestive enzymes, a large number of cells occurred also in the hindgut. PMID:20619264

  14. Effects of cysteine proteinase inhibitors scN and E-64 on southern corn rootworm larval development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The southern corn rootworm (SCRW) can be a serious pest of peanut pods. A laboratory bioassay was developed to test feeding cysteine proteinase inhibitors soyacystatin N (scN) and E-64 against southern corn rootworm reared on artificial diet to determine the effects on larvae development and mortal...

  15. The development of the larval nervous system, musculature and ciliary bands of Pomatoceros lamarckii (Annelida): heterochrony in polychaetes

    PubMed Central

    McDougall, Carmel; Chen, Wei-Chung; Shimeld, Sebastian M; Ferrier, David EK

    2006-01-01

    Background To understand the evolution of animals it is essential to have taxon sampling across a representative spread of the animal kingdom. With the recent rearrangement of most of the Bilateria into three major clades (Ecdysozoa, Lophotrochozoa and Deuterostomia) it has become clear that the Lophotrochozoa are relatively poorly represented in our knowledge of animal development, compared to the Ecdysozoa and Deuterostomia. We aim to contribute towards redressing this balance with data on the development of the muscular, nervous and ciliary systems of the annelid Pomatoceros lamarckii (Serpulidae). We compare our data with other lophotrochozoans. Results P. lamarckii develops locomotory and feeding structures that enable it to become a swimming, planktotrophic larva within 24 hours. Formation of the trochophore includes development of a prototroch, metatroch and neurotroch, development of apical and posterior nervous elements at similar times, and development of musculature around the ciliary bands and digestive tract prior to development of any body wall muscles. The adult nervous and muscular systems are essentially preformed in the late larva. Interestingly, the muscular systems of the larvae and juvenile worms do not include the circular muscles of the body wall, which are considered to be plesiomorphic for annelids, although the possibility that circular muscles develop after these stages cannot be ruled out at this point. Conclusion A comparison between polychaetes shows variability in the timing (heterochrony) of development of body wall muscles and elements of the nervous system. These heterochronies are one route for evolution of different life history strategies, such as adaptations to feeding requirements. PMID:17032451

  16. Larval Development of Aedes aegypti and Aedes albopictus in Peri-Urban Brackish Water and Its Implications for Transmission of Arboviral Diseases

    PubMed Central

    Ramasamy, Ranjan; Surendran, Sinnathamby N.; Jude, Pavilupillai J.; Dharshini, Sangaralingam; Vinobaba, Muthuladchumy

    2011-01-01

    Aedes aegypti (Linnaeus) and Aedes albopictus Skuse mosquitoes transmit serious human arboviral diseases including yellow fever, dengue and chikungunya in many tropical and sub-tropical countries. Females of the two species have adapted to undergo preimaginal development in natural or artificial collections of freshwater near human habitations and feed on human blood. While there is an effective vaccine against yellow fever, the control of dengue and chikungunya is mainly dependent on reducing freshwater preimaginal development habitats of the two vectors. We show here that Ae. aegypti and Ae. albopictus lay eggs and their larvae survive to emerge as adults in brackish water (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish and saline respectively). Brackish water with salinity of 2 to 15 ppt in discarded plastic and glass containers, abandoned fishing boats and unused wells in coastal peri-urban environment were found to contain Ae. aegypti and Ae. albopictus larvae. Relatively high incidence of dengue in Jaffna city, Sri Lanka was observed in the vicinity of brackish water habitats containing Ae. aegypti larvae. These observations raise the possibility that brackish water-adapted Ae. aegypti and Ae. albopictus may play a hitherto unrecognized role in transmitting dengue, chikungunya and yellow fever in coastal urban areas. National and international health authorities therefore need to take the findings into consideration and extend their vector control efforts, which are presently focused on urban freshwater habitats, to include brackish water larval development habitats. PMID:22132243

  17. House and stable fly (Diptera: Muscidae) seasonal abundance, larval development substrates, and natural parasitism on small equine farms in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This 1-year study was designed to determine adult fly population levels and development substrates on four small equine farms. Results showed that pest flies were present year-round, but differences existed in population levels among farms and seasons. Fly larvae were not found on two of the farms, ...

  18. [Standardization of larval development of the sea urchin, Paracentrotus lividus, as tool for the assessment sea water quality].

    PubMed

    Pétinay, Stéphanie; Chataigner, Claire; Basuyaux, Olivier

    2009-12-01

    All stages of development of the sea urchin are of interest in ecotoxicology; the largest number of prior works concerns studies on gametes. Previous studies indicated that the use of sea urchin larvae was difficult because of the need to obtain the parent generations and good quality gametes. Progress in sea urchin culture has allowed one to standardize the method. The proposed technique is based on an evaluation of the number of non-developing fertilized eggs, on the frequency of malformations, and on the length of the larvae at 96 hours, using parents raised under well-controlled conditions. Temperature (18-22 degrees C), salinity (28-34 ppt) and pH (8-8.4) have been fixed to standardize the proposed biological test. Thirty micrograms per litre of copper reduce significantly the length of the larvae and could be used as a positive control. On the other hand, reconstituted sea water permits an optimal development of the larvae and may be used as negative control. A seasonal follow-up of water quality has been achieved to validate the use of this technique in a surveillance network of water quality. The method may be used whatever the salinity, including fresh and brackish waters. PMID:19931848

  19. House and Stable Fly Seasonal Abundance, Larval Development Substrates, and Natural Parasitism on Small Equine Farms in Florida.

    PubMed

    Machtinger, E T; Leppla, N C; Hogsette, J A

    2016-08-01

    House flies, Musca domestica Linnaeus, and stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are common pests on horse farms. The successful use of pupal parasitoids for management of these pests requires knowledge of seasonal fluctuations and biology of the flies as well as natural parasitism levels. However, these dynamics have not been investigated on small equine farms. A 1-year field study began in July 2010, in north central Florida, to determine adult fly population levels and breeding areas on four small equine farms. Weekly surveillance showed that pest flies were present year-round, though there were differences in adult population levels among farms and seasons. Fly development was not confirmed on two of the four small farms, suggesting that subtle differences in husbandry may adversely affect the development of immature flies. In six substrates previously identified as the most common among the farms, stable fly puparia were found overwhelmingly in hay mixed with equine manure and house fly puparia were found in fresh pine shavings mixed with equine manure. Natural parasitism was minimal as expected, but greatest numbers of natural parasitoids collected were of the genus Spalangia. Differences in adult and immature fly numbers recovered emphasizes the need for farm owners to confirm on-site fly development prior to purchase and release of biological control agents. Additionally, due to the low natural parasitism levels and domination of parasitism by Spalangia cameroni, augmentative releases using this species may be the most effective. PMID:26902468

  20. Effect of hypergravity on the Ca/Sr composition of developing otoliths of larval cichlid fish (Oreochromis mossambicus).

    PubMed

    Anken, R H; Ibsch, M; Breuer, J; Rahmann, H

    2001-02-01

    The amounts of calcium and strontium were measured by inductively coupled plasma mass spectrometry (ICP-MS) in saccular and utricular inner ear otoliths (sagittae and lapilli, respectively) of developing cichlid fish. These fish had been maintained for 22 days at 3-g hypergravity conditions within a centrifuge. During this time-span, the animals completed their ontogenetic development from hatch to the free-swimming stage. Neither the morphogenetic development nor the timely onset and gain of performance of the swimming behaviour was impaired by the experimental conditions. Experimental and control animals also did not differ concerning their size (total length). ICP-MS revealed that the otoliths contained significantly less calcium (in microg/otolith) after hyper-g exposure compared to parallelly raised 1-g control specimens (lapilli: 0.74+/-0.21 vs. 1.16+/-0.41; sagittae: 2.09+/-0.49 vs. 2.76+/-0.47). The content of strontium (in microg/otolith: lapilli: 0.0044+/-0.0023 vs. 0.0022+/-0.0013; sagittae: 0.0094+/-0.0026 vs. 0.0081+/-0.0016) and, consequently, the Sr/Ca ratio (Sr/Cax100) was increased (lapilli: 0.607+/-0.267 vs. 0.201+/-0.12; sagittae: 0.439+/-0.093 vs. 0.301+/-0.086). Since the calcium content can be taken as a proxy for otolith weight, and because parallelly undertaken morphometric investigations revealed smaller otoliths (maximum radius and surface area) due to hyper-g exposure, the results suggest that the growth of otoliths at hyper-g is slowed down. Since the concentration of trace elements incorporated into otoliths is likely based on the composition of the respective protein matrix, our findings suggest that the protein metabolism is affected by hypergravity. PMID:11223398

  1. Effects of simulated microgravity on the development of the swimbladder and buoyancy control in larval zebrafish (Danio rerio).

    PubMed

    Lindsey, Benjamin W; Dumbarton, Tristan C; Moorman, Stephen J; Smith, Frank M; Croll, Roger P

    2011-06-01

    The gas-filled swimbladder of teleost fishes provides hydrodynamic lift which counteracts the high density of other body tissues, and thereby allows the fish to achieve neutral buoyancy with minimal energy expenditure. In this study, we examined whether the absence of a constant direction gravitational vector affects the ontogeny of the swimbladder and buoyancy control in zebrafish (Danio rerio). We exposed fertilized eggs to simulated microgravity (SMG) in a closed rotating wall vessel with control eggs placed in a similar but nonrotating container. All eggs hatched in both groups. At 96 hr of postfertilization (hpf), all larvae were removed from the experimental and control vessels. At this point, 62% of the control larvae, but only 14% of SMG-exposed larvae, were observed to have inflated their swimbladder. In addition, the mean volume of the inflated swimbladders was significantly greater in the control larvae compared with larvae raised in SMG. After transfer to open stationary observation tanks, larvae with uninflated swimbladders in both groups swam to the surface to complete inflation, but this process was significantly delayed in larvae exposed to SMG. Initial differences in swimbladder inflation and volume between groups disappeared by 144 hpf. Furthermore, there were no apparent changes in patterns of development and maturation of swimbladder musculature, vasculature, or innervation resulting from SMG exposure at later stages of ontogeny. These data indicate that, despite a transient delay in swimbladder inflation in zebrafish larvae exposed to SMG, subsequent swimbladder development in these animals proceeded similarly to that in normal larvae. PMID:21394929

  2. Bacterial enteritis and the development of the larval digestive tract in olive flounder, Paralichthys olivaceus (Temminck & Schlegel).

    PubMed

    Kim, D-H; Han, H-J; Kim, S-M; Lee, D-C; Park, S-I

    2004-09-01

    Three bacterial isolates obtained from diseased olive flounder larvae, Paralichthys olivaceus, were identified as Vibrio ichthyoenteri based on the results of phenotypic characterization and 16S rRNA gene sequencing studies. Bacterial enteritis was reproduced in 16 and 22 days post-hatch (dph) larvae by administering brine shrimp nauplii, Artemia salina, dosed with the environmental isolates and reference strains of V. ichthyoenteri. To investigate the effect of the disease on development of the stomach, a pepsin activity assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis of the expression of the pepsinogen gene were performed. Expression of olive flounder pepsinogen was detected from 30-dph larvae and the increased level of pepsin activity coincided with reduced susceptibility to the disease. Growth rates of V. ichthyoenteri, V. anguillarum and Edwardsiella tarda were tested in artificial stomach conditions using HCl and porcine pepsin. All the strains of V. ichthyoenteri were inhibited by low pH conditions which corresponded with an increase in pepsin levels. This suggests that differentiation of the stomach in olive flounder larvae and juveniles, an essential physiological development, also provides the host with a non-immunological defence mechanism. PMID:15357708

  3. Octylphenol and UV-B radiation alter larval development and hypothalamic gene expression in the leopard frog (Rana pipiens).

    PubMed Central

    Crump, Douglas; Lean, David; Trudeau, Vance L

    2002-01-01

    We assessed octylphenol (OP), an estrogenic endocrine-disrupting chemical, and UV-B radiation, a known stressor in amphibian development, for their effects on hypothalamic gene expression and premetamorphic development in the leopard frog Rana pipiens. Newly hatched tadpoles were exposed for 10 days to OP alone at two different dose levels; to subambient UV-B radiation alone; and to two combinations of OP and UV-B. Control animals were exposed to ethanol vehicle (0.01%) exposure, a subset of tadpoles from each treatment group was raised to metamorphosis to assess differences in body weight and time required for hindlimb emergence. Tadpoles from one of the OP/UV-B combination groups had greater body weight and earlier hindlimb emergence (p < 0.05), but neither OP nor UV-B alone produced significant changes in body weight or hindlimb emergence, indicating a potential mechanism of interaction between OP and UV-B. We hypothesized that the developing hypothalamus might be a potential environmental sensor for neurotoxicologic studies because of its role in the endocrine control of metamorphosis. We used a differential display strategy to identify candidate genes differentially expressed in the hypothalamic region of the exposed tadpoles. Homology cloning was performed to obtain R. pipiens glutamate decarboxylases--GAD65 and GAD67, enzymes involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA). cDNA expression profiles revealed that OP and UV-B affected the levels of several candidate transcripts in tadpole (i.e., Nck, Ash, and phospholipase C gamma-binding protein 4 and brain angiogenesis inhibitor-3) and metamorph (i.e., GAD67, cytochrome C oxidase, and brain angiogenesis inhibitor-2 and -3) brains. This study represents a novel approach in toxicology that combines physiologic and molecular end points and indicates that levels of OP commonly found in the environment and subambient levels of UV-B alter the expression of important hypothalamic

  4. Mixed Effects of Elevated pCO2 on Fertilisation, Larval and Juvenile Development and Adult Responses in the Mobile Subtidal Scallop Mimachlamys asperrima (Lamarck, 1819)

    PubMed Central

    Scanes, Elliot; Parker, Laura M.; O’Connor, Wayne A.; Ross, Pauline M.

    2014-01-01

    Ocean acidification is predicted to have severe consequences for calcifying marine organisms especially molluscs. Recent studies, however, have found that molluscs in marine environments with naturally elevated or fluctuating CO2 or with an active, high metabolic rate lifestyle may have a capacity to acclimate and be resilient to exposures of elevated environmental pCO2. The aim of this study was to determine the effects of near future concentrations of elevated pCO2 on the larval and adult stages of the mobile doughboy scallop, Mimachlamys asperrima from a subtidal and stable physio-chemical environment. It was found that fertilisation and the shell length of early larval stages of M. asperrima decreased as pCO2 increased, however, there were less pronounced effects of elevated pCO2 on the shell length of later larval stages, with high pCO2 enhancing growth in some instances. Byssal attachment and condition index of adult M. asperrima decreased with elevated pCO2, while in contrast there was no effect on standard metabolic rate or pHe. The responses of larval and adult M. asperrima to elevated pCO2 measured in this study were more moderate than responses previously reported for intertidal oysters and mussels. Even this more moderate set of responses are still likely to reduce the abundance of M. asperrima and potentially other scallop species in the world’s oceans at predicted future pCO2 levels. PMID:24733125

  5. Laboratory evaluation of novaluron as a development site treatment for controlling larval horn flies, house flies, and stable flies (Diptera: Muscidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A granular formulation of novaluron (Novaluron 0.2G, 0.2% AI), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.), house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.), in cow manure. V...

  6. Nectar sugar limits larval growth of solitary bees (Hymenoptera: Megachilidae).

    PubMed

    Burkle, Laura; Irwin, Rebecca

    2009-08-01

    The bottom-up effects of plant food quality and quantity can affect the growth, survival, and reproduction of herbivores. The larvae of solitary bee pollinators, consumers of nectar and pollen, are also herbivores. Although pollen quantity and quality are known to be important for larval growth, little is known about how nectar quality limits solitary bee performance. By adding different levels of nectar sugar directly to solitary bee provisions in the subalpine of Colorado, we tested the degree to which larval performance (development time, mass, and survival) was limited by nectar sugar. We found that larval growth increased with nectar sugar addition, with the highest larval mass in the high nectar-sugar addition treatment (50% honey solution). The shortest larval development time was observed in the low nectar-sugar addition treatment (25% honey solution). Neither low nor high nectar-sugar addition affected larval survival. This study suggests that, in addition to pollen, nectar-sugar concentration can limit solitary bee larval growth and development, and nectar should be considered more explicitly as a currency governing foraging decisions related to producing optimally sized offspring. The availability and sugar content of nectar may scale up to affect bee fitness, population dynamics, and plant-pollinator mutualisms. PMID:19689912

  7. Comparing salinity tolerance in embryonic and larval development of two species of water strider, Aquarius paludum and Gerris latiabdominis (Hemiptera: Gerridae).

    PubMed

    Kishi, Manabu; Harada, Tetsuo; Fujisaki, Kenji

    2013-08-01

    Water strider Aquarius paludum (Fabricius) is a cosmopolitan species colonizes mainly freshwater but occasionally brackish habitats throughout the Palearctic and Oriental regions. Water strider Gerris latiabdominis (Miyamoto) is a common species in Japan lives in temporary habitats as freshwater paddy fields. These two species often occur syntopically. We investigated differences in the developmental response to brackish water during embryonic and larval stages between the two species. Eggs were exposed to 0-1.8% NaCl solutions within 24 h of oviposition. Larvae of G. latiabdominis were exposed to salinities of 0, 0.5%, and 0.9% from the first instar until adult emergence. Limits of NaCl concentration for hatching were 1.3% and 1.0% for A. paludum and G. latiabdominis, respectively. The hatching rate of G. latiabdominis was lower than that of A. paludum at salinities ≥ 0.9%. The period of embryonic development of G. latiabdominis was more prolonged than that of A. paludum at a given salinity. Although the salinity tolerance of G. latiabdominis was lower than that of A. paludum, our results suggest G. latiabdominis has the physiological capacity to expand into brackish waters. High and low salinity tolerances of A. paludum and G. latiabdominis, respectively, reflect the relatively wide range of habitat salinities utilized by A. paludum and the relatively restricted habitats preferred by G. latiabdominis. The high salinity tolerance of A. paludum could be an important factor contributing to their cosmopolitan distribution because high tolerance to salinity means the possibility of them to be dispersed via ocean or sea to other continents and islands. PMID:23955948

  8. Utilization of blueberry by the lappet moth, Streblote panda Hübner (Lepidoptera: Lasiocampidae): survival, development, and larval performance.

    PubMed

    Calvo, D; Molina, J Ma

    2004-06-01

    The lappet moth, Streblote panda Hübner [1820] (Lasiocampidae), is a common species found in blueberry, Vaccinium spp. (Ericaceae) fields of Western Andalusia. The biology of this species as well as the extent to which its larvae can use and survive on blueberry is unknown. In this study, the suitability to larvae of several blueberry cultivars was studied. Larvae were grown under controlled laboratory conditions on excised foliage of six blueberry cultivars. Survival, development, and food use were determined for first and fifth instars. According to our results, blueberry has become an alternative host plant for S. panda in southwestern Andalusia. Low growth rates and efficiencies of use of food were observed. Lower gross efficiency of growth was found for larvae fed blueberry 'Sharpblue', despite a higher apparent digestibility of this cultivar. Larvae reared on this cultivar had the highest mortality, increased developmental time, and used a greater part of metabolism for maintenance. Herbivore pressure may be increased with the widespread planting of the most suitable cultivars 'Misty' and 'O'Neal', whereas 'Sharpblue' and'Climax' seem to be the least suitable host plants. These data provide useful information for planning and managing blueberry orchards in the presence of S. panda populations. PMID:15279278

  9. The Importance of Drains for the Larval Development of Lymphatic Filariasis and Malaria Vectors in Dar es Salaam, United Republic of Tanzania

    PubMed Central

    Castro, Marcia C.; Kanamori, Shogo; Kannady, Khadija; Mkude, Sigsbert; Killeen, Gerry F.; Fillinger, Ulrike

    2010-01-01

    Background Dar es Salaam has an extensive drain network, mostly with inadequate water flow, blocked by waste, causing flooding after rainfall. The presence of Anopheles and Culex larvae is common, which is likely to impact the transmission of lymphatic filariasis and malaria by the resulting adult mosquito populations. However, the importance of drains as larval habitats remains unknown. Methodology Data on mosquito larval habitats routinely collected by the Urban Malaria Control Program (UMCP) and a special drain survey conducted in 2006 were used to obtain a typology of habitats. Focusing on drains, logistic regression was used to evaluate potential factors impacting the presence of mosquito larvae. Spatial variation in the proportion of habitats that contained larvae was assessed through the local Moran's I indicator of spatial association. Principal Findings More than 70% of larval habitats in Dar es Salaam were human-made. Aquatic habitats associated with agriculture had the highest proportion of Anopheles larvae presence and the second highest of Culex larvae presence. However, the majority of aquatic habitats were drains (42%), and therefore, 43% (1,364/3,149) of all culicine and 33% (320/976) of all anopheline positive habitats were drains. Compared with drains where water was flowing at normal velocity, the odds of finding Anopheles and Culex larvae were 8.8 and 6.3 (p<0.001) times larger, respectively, in drains with stagnant water. There was a positive association between vegetation and the presence of mosquito larvae (p<0.001). The proportion of habitats with mosquito larvae was spatially correlated. Conclusion Restoring and maintaining drains in Dar es Salaam has the potential to eliminate more than 40% of all potential mosquito larval habitats that are currently treated with larvicides by the UMCP. The importance of human-made larval habitats for both lymphatic filariasis and malaria vectors underscores the need for a synergy between on-going control

  10. Changes in digestive enzyme activities during larval development of Chinese loach Paramisgurnus dabryanus (Dabry de Thiersant, 1872).

    PubMed

    Zhang, Yun-Long; Wu, Qiao-Wan; Hu, Wei-Hua; Wang, Fan; Zhao, Zhong-Bo; He, Hui; Shao, Wei-Han; Fan, Qi-Xue

    2015-12-01

    The digestive physiology of Chinese loach (Paramisgurnus dabryanus) was studied by assessing the specific and total activities of different pancreatic (trypsin, chymotrypsin, amylase and lipase), gastric (pepsin) and intestinal (alkaline phosphatase and leucine-aminopeptidase) enzymes from hatching to 40 days after hatching (DAH). Larvae were reared at 24.4 ± 0.4 °C and fed with rotifers from mouth opening (4 DAH) to 15 DAH, from 10 to 35 DAH with Cladocera and from 30 to 40 DAH with compound diet. Enzyme activities for trypsin, chymotrypsin, amylase and lipase were detected before the onset of exogenous feeding, indicating that these enzymes were genetically pre-programmed. Most of the pancreatic enzyme specific activities increased until 20 DAH and decreased thereafter. The pepsin activity of Chinese loach was firstly detected at 30 DAH, indicating the appearance of functional gastric gland. Alkaline phosphatase specific activity was detected from hatching onward, showed marked increase and reached the second peak at 20 DAH, while a gradual increase in specific leucine-aminopeptidase activity was observed until the end of the experiment. Accordingly, the larvae of Chinese loach possess a functional digestive system before the onset of exogenous feeding and the digestive capacity gradually increases as development progresses. The abrupt increase in intestinal enzyme activities between 10 and 20 DAH demonstrates onset of juvenile-like digestive mode in Chinese loach larvae. The increase in pepsin activity after 30 DAH indicates the shift from alkaline to acidic digestion in Chinese loach larvae, which may be considered as the onset of weaning. PMID:26232086

  11. Drosophila adult and larval pheromones modulate larval food choice

    PubMed Central

    Farine, Jean-Pierre; Cortot, Jérôme; Ferveur, Jean-François

    2014-01-01

    Insects use chemosensory cues to feed and mate. In Drosophila, the effect of pheromones has been extensively investigated in adults, but rarely in larvae. The colonization of natural food sources by Drosophila buzzatii and Drosophila simulans species may depend on species-specific chemical cues left in the food by larvae and adults. We identified such chemicals in both species and measured their influence on larval food preference and puparation behaviour. We also tested compounds that varied between these species: (i) two larval volatile compounds: hydroxy-3-butanone-2 and phenol (predominant in D. simulans and D. buzzatii, respectively), and (ii) adult cuticular hydrocarbons (CHs). Drosophila buzzatii larvae were rapidly attracted to non-CH adult conspecific cues, whereas D. simulans larvae were strongly repulsed by CHs of the two species and also by phenol. Larval cues from both species generally reduced larval attraction and pupariation on food, which was generally—but not always—low, and rarely reflected larval response. As these larval and adult pheromones specifically influence larval food search and the choice of a pupariation site, they may greatly affect the dispersion and survival of Drosophila species in nature. PMID:24741012

  12. Bean Type Modifies Larval Competition in Zabrotes subfasciatus (Chrysomelidae: Bruchinae).

    PubMed

    Oliveira, S O D; Rodrigues, A S; Vieira, J L; Rosi-Denadai, C A; Guedes, N M P; Guedes, R N C

    2015-08-01

    Larval competition is particularly prevalent among grain beetles that remain within their mother-selected grain throughout development, and the behavioral process of competition is usually inferred by the competition outcome. The Mexican bean weevil Zabrotes subfasciatus (Boheman) is subjected to resource availability variation because of the diversity of common bean types and sizes, from small (e.g., kidney beans) to large (e.g., cranberry beans). The competition process was identified in the Mexican bean weevil reared on kidney and cranberry beans by inference from the competition outcome and by direct observation through digital X-ray imaging. Increased larval density negatively affected adult emergence in kidney beans and reduced adult body mass in both kidney and cranberry beans. Developmental time was faster in cranberry beans. The results allowed for increased larval fitness (i.e., higher larval biomass produced per grain), with larval density reaching a maximum plateau >5 hatched larvae per kidney bean, whereas in cranberry beans, larval fitness linearly increased with density to 13 hatched larvae per bean. These results, together with X-ray imaging without evidence of direct aggressive interaction among larvae, indicate scramble competition, with multiple larvae emerging per grain. However, higher reproductive output was detected for adults from lower density competition with better performance on cranberry beans. Larger populations and fitter adults are expected in intermediate larval densities primarily in cranberry beans where grain losses should be greater. PMID:26470357

  13. Contribution of larval nutrition to adult reproduction in Drosophila melanogaster.

    PubMed

    Aguila, Jerell R; Hoshizaki, Deborah K; Gibbs, Allen G

    2013-02-01

    Within the complex life cycle of holometabolous insects, nutritional resources acquired during larval feeding are utilized by the pupa and the adult. The broad features of the transfer of larval resources to the pupae and the allocation of larval resources in the adult have been described by studies measuring and tracking macronutrients at different developmental stages. However, the mechanisms of resource transfer from the larva and the factors regulating the allocation of these resources in the adult between growth, reproduction and somatic maintenance are unknown. Drosophila melanogaster presents a tractable system in which to test cellular and tissue mechanisms of resource acquisition and allocation because of the detailed understanding of D. melanogaster development and the experimental tools to manipulate its tissues across developmental stages. In previous work, we demonstrated that the fat body of D. melanogaster larvae is important for survival of starvation stress in the young adult, and suggested that programmed cell death of the larval fat cells in the adult is important for allocation of resources for female reproduction. Here, we describe the temporal uptake of larval-derived carbon by the ovaries, and demonstrate the importance of larval fat-cell death in the maturation of the ovary and in fecundity. Larvae and adults were fed stable carbon isotopes to follow the acquisition of larval-derived carbon by the adult ovaries. We determined that over half of the nutrients acquired by the ovaries in 2-day-old adult females are dependent upon the death of the fat cells. Furthermore, when programmed cell death is inhibited in the larval fat cells, ovarian development was depressed and fecundity was reduced. PMID:23038728

  14. Larval descriptions of the family Porcellanidae: A worldwide annotated compilation of the literature (Crustacea, Decapoda).

    PubMed

    Vela, María José; González-Gordillo, Juan Ignacio

    2016-01-01

    For most of the family Porcellanidae, which comprises 283 species, larval development remains to be described. Full development has been only described for 52 species, while part of the larval cycle has been described for 45 species. The importance of knowing the complete larval development of a species goes beyond allowing the identification of larval specimens collected in the plankton. Morphological larval data also constitute a support to cladistic techniques used in the establishment of the phylogenetic status (see Hiller et al. 2006, Marco-Herrero et al. 2013). Nevertheless, the literature on the larval development of this family is old and widely dispersed and in many cases it is difficult to collect the available information on a particular taxon. Towards the aim of facilitating future research, all information available on the larval development of porcellanids has been compiled. Following the taxonomic checklist of Porcellanidae proposed by Osawa and McLaughlin (2010), a checklist has been prepared that reflects the current knowledge about larval development of the group including larval stages and the method used to obtain the larvae, together with references. Those species for which the recognised names have been changed according to Osawa and McLaughlin (2010) are indicated. PMID:27081332

  15. Larval descriptions of the family Porcellanidae: A worldwide annotated compilation of the literature (Crustacea, Decapoda)

    PubMed Central

    Vela, María José; González-Gordillo, Juan Ignacio

    2016-01-01

    Abstract For most of the family Porcellanidae, which comprises 283 species, larval development remains to be described. Full development has been only described for 52 species, while part of the larval cycle has been described for 45 species. The importance of knowing the complete larval development of a species goes beyond allowing the identification of larval specimens collected in the plankton. Morphological larval data also constitute a support to cladistic techniques used in the establishment of the phylogenetic status (see Hiller et al. 2006, Marco-Herrero et al. 2013). Nevertheless, the literature on the larval development of this family is old and widely dispersed and in many cases it is difficult to collect the available information on a particular taxon. Towards the aim of facilitating future research, all information available on the larval development of porcellanids has been compiled. Following the taxonomic checklist of Porcellanidae proposed by Osawa and McLaughlin (2010), a checklist has been prepared that reflects the current knowledge about larval development of the group including larval stages and the method used to obtain the larvae, together with references. Those species for which the recognised names have been changed according to Osawa and McLaughlin (2010) are indicated. PMID:27081332

  16. Can Georges Bank larval cod survive on a calanoid diet?

    NASA Astrophysics Data System (ADS)

    Lynch, Daniel R.; Lewis, Craig V. W.; Werner, Francisco E.

    A simple conceptual model is developed for larval fish feeding on stage-structured prey populations, in an Eulerian framework. The model combines simplified contemporary models of larval fish trophodynamics, zooplankton population dynamics, and hydrodynamic turbulence. The Eulerian view allows instructive maps of larval feeding and growth rates for individual prey species, alone or in combination. Decadally averaged MARMAP surveys of Calanus finmarchicus and Pseudocalanus spp. are analyzed for the March-April period. Quasi-static population dynamics are used to infer the abundance of the smallest stages from adult female abundance. Computed growth rates show that Calanus alone is insufficient to support the smallest cod larvae (4 and 6 mm), but provides good growth (⩾10%/day) for large larvae (10, 12 mm). Pseudocalanus alone provides generally good growth for all larvae but is mismatched spatially with observed cod spawning and subsequent larval advection. Both species together provide good growth, matched spatially with larval cod, for 6 mm and larger larvae. A dietary supplement beyond these two species is needed for the smallest larvae. The procedure provides a general method for mapping observations of zooplankton abundance, distribution and reproductive status, and their relevance to larval fish survival, when the smallest stages are not observable.

  17. An age–size reaction norm yields insight into environmental interactions affecting life-history traits: a factorial study of larval development in the malaria mosquito Anopheles gambiae sensu stricto

    PubMed Central

    Phelan, Conan; Rotiberg, Bernard D

    2013-01-01

    Environmental factors frequently act nonindependently to determine growth and development of insects. Because age and size at maturity strongly influence population dynamics, interaction effects among environmental variables complicate the task of predicting dynamics of insect populations under novel conditions. We reared larvae of the African malaria mosquito Anopheles gambiae sensu stricto (s.s.) under three factors relevant to changes in climate and land use: food level, water depth, and temperature. Each factor was held at two levels in a fully crossed design, for eight experimental treatments. Larval survival, larval development time, and adult size (wing length) were measured to indicate the importance of interaction effects upon population-level processes. For age and size at emergence, but not survival, significant interaction effects were detected for all three factors, in addition to sex. Some of these interaction effects can be understood as consequences of how the different factors influence energy usage in the context of a nonindependent relationship between age and size. Experimentally assessing interaction effects for all potential future sets of conditions is intractable. However, considering how different factors affect energy usage within the context of an insect's evolved developmental program can provide insight into the causes of complex environmental effects on populations. PMID:23919132

  18. Incidence and impact of axial malformations in larval bullfrogs (Rana catesbeiana) developing in sites polluted by a coal-burning power plant

    SciTech Connect

    Hopkins, W.A.; Congdon, J.; Ray, J.K.

    2000-04-01

    Amphibian malformations have recently received much attention from the scientific community, but few studies have provided evidence linking environmental pollution to larval amphibian malformations in the field. The authors document an increased incidence of axial malformations in bullfrog larvae (Rana catesbeiana) inhabiting two sites contaminated with coal combustion wastes. In the polluted sites, 18 and 37% of larvae exhibited lateral curvatures of the spine, whereas zero and 4% of larvae from two reference sites had similar malformations. Larvae from the most heavily polluted site had significantly higher tissue concentrations of potentially toxic trace elements, including As, Cd, Se, Cu, Cr, and V, compared with conspecifics from the reference sites. In addition, malformed larvae from the cost contaminated site had decreased swimming speeds compared with those of normal larvae from the same site. The authors hypothesize that the complex mixture of contaminants produced by coal combustion is responsible for the high incidence of malformations and associated effects on swimming performance.

  19. Drosophila E-cadherin and its binding partner Armadillo/ beta-catenin are required for axonal pathway choices in the developing larval brain.

    PubMed

    Fung, Siaumin; Wang, Fay; Spindler, Shana R; Hartenstein, Volker

    2009-08-15

    The fly brain is formed by approximately hundred paired lineages of neurons, each lineage derived from one neuroblast. Embryonic neuroblasts undergo a small number of divisions and produce the primary neurons that form the functioning larval brain. In the larva, neuroblasts produce the secondary lineages that make up the bulk of the adult brain. Axons of a given secondary lineage fasciculate with each other and form a discrete bundle, the secondary axon tract (SAT). Secondary axon tracts prefigure the long axon connections of the adult brain, and therefore pathway choices of SATs made in the larva determine adult brain circuitry. Drosophila Shotgun/E-cadherin (DE-cad) and its binding partner Armadillo/beta-catenin (beta-cat) are expressed in newly born secondary neurons and their axons. The fact that the highly diverse, yet invariant pattern of secondary lineages and SATs has been recently mapped in the wild-type brain enabled us to investigate the role of DE-cad and beta-cat with the help of MARCM clones. Clones were validated by their absence of DE-cad immuno-reactivity. The most significant phenotype consists in the defasciculation and an increased amount of branching of SATs at the neuropile-cortex boundary, as well as subtle changes in the trajectory of SATs within the neuropile. In general, only a fraction of mutant clones in a given lineage showed structural abnormalities. Furthermore, although they all globally express DE-cad and beta-cat, lineages differ in their requirement for DE-cad function. Some lineages never showed morphological abnormalities in MARCM clones, whereas others reacted with abnormal branching and changes in SAT trajectory at a high frequency. We conclude that DE-cad/beta-cat form part of the mechanism that control branching and trajectory of axon tracts in the larval brain. PMID:19520071

  20. Drosophila E-cadherin and its binding partner Armadillo/ β-catenin are required for axonal pathway choices in the developing larval brain

    PubMed Central

    Fung, Siaumin; Wang, Fay; Spindler, Shana R; Hartenstein, Volker

    2009-01-01

    The fly brain is formed by approximately hundred paired lineages of neurons, each lineage derived from one neuroblast. Embryonic neuroblasts undergo a small number of divisions and produce the primary neurons that form the functioning larval brain. In the larva, neuroblasts produce the secondary lineages that make up the bulk of the adult brain. Axons of a given secondary lineage fasciculate with each other and form a discrete bundle, the secondary axon tract (SAT). Secondary axon tracts prefigure the long axon connections of the adult brain, and therefore pathway choices of SATs made in the larva determine adult brain circuitry. Drosophila Shotgun/E-cadherin (DE-cad) and its binding partner Armadillo/β-catenin (β-cat) are expressed in newly born secondary neurons and their axons. The fact that the highly diverse, yet invariant pattern of secondary lineages and SATs has been recently mapped in the wild-type brain enabled us to investigate the role of DE-cad and β-cat with the help of MARCM clones. Clones were validated by their absence of DE-cad immuno-reactivity. The most significant phenotype consists in the defasciculation and an increased amount of branching of SATs at the neuropile-cortex boundary, as well as subtle changes in the trajectory of SATs within the neuropile. In general, only a fraction of mutant clones in a given lineage showed structural abnormalities. Furthermore, although they all globally express DE-cad and β-cat, lineages differ in their requirement for DE-cad function. Some lineages never showed morphological abnormalities in MARCM clones, whereas others reacted with abnormal branching and changes in SAT trajectory at a high frequency. We conclude that DE-cad/β-cat form part of the mechanism that control branching and trajectory of axon tracts in the larval brain. PMID:19520071

  1. Expression and light-triggered movement of rhodopsins in the larval visual system of mosquitoes

    PubMed Central

    Rocha, Manuel; Kimler, Kyle J.; Leming, Matthew T.; Hu, Xiaobang; Whaley, Michelle A.; O'Tousa, Joseph E.

    2015-01-01

    ABSTRACT During the larval stages, the visual system of the mosquito Aedes aegypti contains five stemmata, often referred to as larval ocelli, positioned laterally on each side of the larval head. Here we show that stemmata contain two photoreceptor types, distinguished by the expression of different rhodopsins. The rhodopsin Aaop3 (GPROP3) is expressed in the majority of the larval photoreceptors. There are two small clusters of photoreceptors located within the satellite and central stemmata that express the rhodopsin Aaop7 (GPROP7) instead of Aaop3. Electroretinogram analysis of transgenic Aaop7 Drosophila indicates that Aaop3 and Aaop7, both classified as long-wavelength rhodopsins, possess similar but not identical spectral properties. Light triggers an extensive translocation of Aaop3 from the photosensitive rhabdoms to the cytoplasmic compartment, whereas light-driven translocation of Aaop7 is limited. The results suggest that these photoreceptor cell types play distinct roles in larval vision. An additional component of the larval visual system is the adult compound eye, which starts to develop at the anterior face of the larval stemmata during the 1st instar stage. The photoreceptors of the developing compound eye show rhodopsin expression during the 4th larval instar stage, consistent with indications from previous reports that the adult compound eye contributes to larval and pupal visual capabilities. PMID:25750414

  2. Butterfly oviposition preference is not related to larval performance on a polyploid herb.

    PubMed

    König, Malin A E; Wiklund, Christer; Ehrlén, Johan

    2016-05-01

    The preference-performance hypothesis predicts that female insects maximize their fitness by utilizing host plants which are associated with high larval performance. Still, studies with several insect species have failed to find a positive correlation between oviposition preference and larval performance. In the present study, we experimentally investigated the relationship between oviposition preferences and larval performance in the butterfly Anthocharis cardamines. Preferences were assessed using both cage experiments and field data on the proportion of host plant individuals utilized in natural populations. Larval performance was experimentally investigated using larvae descending from 419 oviposition events by 21 females on plants from 51 populations of two ploidy types of the perennial herb Cardamine pratensis. Neither ploidy type nor population identity influenced egg survival or larval development, but increased plant inflorescence size resulted in a larger final larval size. There was no correlation between female oviposition preference and egg survival or larval development under controlled conditions. Moreover, variation in larval performance among populations under controlled conditions was not correlated with the proportion of host plants utilized in the field. Lastly, first instar larvae added to plants rejected for oviposition by butterfly females during the preference experiment performed equally well as larvae growing on plants chosen for oviposition. The lack of a correlation between larval performance and oviposition preference for A. cardamines under both experimental and natural settings suggests that female host choice does not maximize the fitness of the individual offspring. PMID:27217940

  3. Cardiorespiratory ontogeny and response to environmental hypoxia of larval spiny lobster, Sagmariasus verreauxi.

    PubMed

    Fitzgibbon, Quinn P; Ruff, Nicole; Battaglene, Stephen C

    2015-06-01

    Cardiorespiratory function is vital to an organism's ability to respond to environmental stress and analysis of cardiorespiratory capacity of species or life stages can elucidate vulnerability to climate change. Spiny lobsters have one of the most complex pelagic larval life cycles of any invertebrate and recently there has been an unexplained decline in post-larval recruitment for a number of species. We conducted the first analysis of the larval ontogeny of oxygen consumption, heart rate, maxilla 2 ventilation rate and oxyregulatory capacity of the spiny lobster, Sagmariasus verreauxi, to gain insight into their vulnerability to ocean change and to investigate life stage specific sensitivity to temperature-dependent oxygen limitation. In normoxia, heart and maxilla 2 ventilation rates increased in early larval development before declining, which we hypothesise is related to the transition from myogenic to neurogenic cardiac control. Maxilla 2 ventilation rate was sensitive to hypoxia at all larval stages, while heart rate was only sensitive to hypoxia in the late phyllosoma stages. Oxygen consumption conformed to environmental hypoxia at all larval stages. Spiny lobster larvae have limited respiratory control due to immature gas exchange physiology, compounded by their exceptionally large size. The lack of oxyregulatory ability suggests that all development stages are vulnerable to changes in sea temperature and oxygen availability. The synergetic stressors of increased temperature and reduced dissolved oxygen in the marine environment will diminish spiny lobster larval performance, increasing the challenge to achieve their extended larval life cycle, which may contribute to declines in post-larval recruitment. PMID:25683612

  4. Burrowing activities of the larval lamprey

    USGS Publications Warehouse

    Sawyer, Philip J.

    1959-01-01

    Since the appearance in 1950 of Applegate's work on the sea lamprey in Michigan (U. S. Fish and Wildl. Serv., Spec. Sci. Rept.; Fish, No. 55) and the subsequent development of means to control lampreys in the Great Lakes, biologists have accumulated much additional information on adult lampreys. Larval lampreys, however, are difficult animals to observe in the field, and many facets of their behavior are still unknown. While working with the U. S. Fish and Wildlife Service, I kept ammocetes in captivity, and was able to observe their burrowing activities.

  5. Location Isn’t Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment

    PubMed Central

    Donahue, Megan J.; Karnauskas, Mandy; Toews, Carl; Paris, Claire B.

    2015-01-01

    Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward. PMID:26103162

  6. Location Isn't Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment.

    PubMed

    Donahue, Megan J; Karnauskas, Mandy; Toews, Carl; Paris, Claire B

    2015-01-01

    Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward. PMID:26103162

  7. Quantifying the drivers of larval density patterns in two tropical mosquito species to maximize control efficiency.

    PubMed

    De Little, Siobhan C; Bowman, David M J S; Whelan, Peter I; Brook, Barry W; Bradshaw, Corey J A

    2009-08-01

    Understanding the contributions of environmental variation and density feedbacks to changes in vector populations is essential for designing effective vector control. We analyzed monitoring datasets describing larval densities over 7 yr of the two dominant mosquito species, Aedes vigilax (Skuse) and Culex annulirostris (Skuse), of the greater Darwin area (Northern Territory, Australia). Using generalized linear and linear mixed-effects models, we tested hypotheses regarding the environmental determinants of spatio-temporal patterns in relative larval abundance in both species. The most important spatial drivers of Ae. vigilax and Cx. annulirostris larval densities were elevation and water presence. Ae. vigilax density correlates negatively with elevation, whereas there was a positive relationship between Cx. annulirostris density and elevation. These results show how larval habitats used by the saltwater-influenced breeder Ae. vigilax and the obligate freshwater breeder Cx. annulirostris are separated in a tidally influenced swamp. The models examining temporal drivers of larval density also identified this discrimination between freshwater and saltwater habitats. Ae. vigilax larval densities were positively related to maximum tide height and high tide frequency, whereas Cx. annulirostris larval densities were positively related to elevation and rainfall. Adult abundance in the previous month was the most important temporal driver of larval densities in both species, providing a clear dynamical link between the two main life phases in mosquito development. This study shows the importance of considering both spatial and temporal drivers, and intrinsic population dynamics, when planning vector control strategies to reduce larval density, adult population density, and disease transmission effectively. PMID:19689879

  8. 'Peer pressure' in larval Drosophila?

    PubMed

    Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

    2014-01-01

    Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on 'peer pressure', that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. PMID:24907371

  9. Effects of embryonic ethanol exposure at low doses on neuronal development, voluntary ethanol consumption and related behaviors in larval and adult zebrafish: Role of hypothalamic orexigenic peptides.

    PubMed

    Sterling, M E; Chang, G-Q; Karatayev, O; Chang, S Y; Leibowitz, S F

    2016-05-01

    Embryonic exposure to ethanol is known to affect neurochemical systems in rodents and increase alcohol drinking and related behaviors in humans and rodents. With zebrafish emerging as a powerful tool for uncovering neural mechanisms of numerous diseases and exhibiting similarities to rodents, the present report building on our rat studies examined in zebrafish the effects of embryonic ethanol exposure on hypothalamic neurogenesis, expression of orexigenic neuropeptides, and voluntary ethanol consumption and locomotor behaviors in larval and adult zebrafish, and also effects of central neuropeptide injections on these behaviors affected by ethanol. At 24h post-fertilization, zebrafish embryos were exposed for 2h to ethanol, at low concentrations of 0.25% and 0.5%, in the tank water. Embryonic ethanol compared to control dose-dependently increased hypothalamic neurogenesis and the proliferation and expression of the orexigenic peptides, galanin (GAL) and orexin (OX), in the anterior hypothalamus. These changes in hypothalamic peptide neurons were accompanied by an increase in voluntary consumption of 10% ethanol-gelatin and in novelty-induced locomotor and exploratory behavior in adult zebrafish and locomotor activity in larvae. After intracerebroventricular injection, these peptides compared to vehicle had specific effects on these behaviors altered by ethanol, with GAL stimulating consumption of 10% ethanol-gelatin more than plain gelatin food and OX stimulating novelty-induced locomotor behavior while increasing intake of food and ethanol equally. These results, similar to those obtained in rats, suggest that the ethanol-induced increase in genesis and expression of these hypothalamic peptide neurons contribute to the behavioral changes induced by embryonic exposure to ethanol. PMID:26778786

  10. Effects of Underwater Turbine Noise on Crab Larval Metamorphosis.

    PubMed

    Pine, Matthew K; Jeffs, Andrew G; Radford, Craig A

    2016-01-01

    The development of marine tidal turbines has advanced at a rapid rate over the last decade but with little detailed understanding of the potential noise impacts on invertebrates. Previous research has shown that underwater reef noise plays an important role in mediating metamorphosis in many larval crabs and fishes. New research suggests that underwater estuarine noise may also mediate metamorphosis in estuarine crab larvae and that the noise emitted from underwater tidal and sea-based wind turbines may significantly influence larval metamorphosis in estuarine crabs. PMID:26611041

  11. Adult beetles compensate for poor larval food conditions.

    PubMed

    Müller, Thorben; Müller, Caroline

    2016-05-01

    Life history traits of herbivores are highly influenced by the quality of their hosts, i.e., the composition of primary and secondary plant metabolites. In holometabolous insects, larvae and adults may face different host plants, which differ in quality. It has been hypothesised that adult fitness is either highest when larval and adult environmental conditions match (environmental matching) or it may be mainly determined by optimal larval conditions (silver spoon effect). Alternatively, the adult stage may be most decisive for the actual fitness, independent of larval food exposure, due to adult compensation ability. To determine the influence of constant versus changing larval and adult host plant experiences on growth performance, fitness and feeding preferences, we carried out a match-mismatch experiment using the mustard leaf beetle, Phaedon cochleariae. Larvae and adults were either constantly reared on watercress (natural host) or cabbage (crop plant) or were switched after metamorphosis to the other host. Growth, reproductive traits and feeding preferences were determined repeatedly over lifetime and host plant quality traits analysed. Differences in the host quality led to differences in the development time and female reproduction. Egg numbers were significantly influenced by the host plant species experienced by the adults. Thus, adults were able to compensate for poor larval conditions. Likewise, the current host experience was most decisive for feeding preferences; in adult beetles a feeding preference was shaped regardless of the larval host plant. Larvae or adults reared on the more nutritious host, cabbage, showed a higher preference for this host. Hence, beetles most likely develop a preference when gaining a direct positive feedback in terms of an improved performance, whereby the current experience matters the most. Highly nutritious crop plants may be, in consequence, all the more exploited by potential pests that may show a high plasticity in

  12. Aspects of larval, post-larval and juvenile ecology of Macrobrachium petersi (Hilgendorf) in the Keiskamma estuary, South Africa

    NASA Astrophysics Data System (ADS)

    Read, G. H. L.

    1985-10-01

    Although Macrobrachium petersi has nine larval stages, only stage I and a minimal number of stage II M. petersi larvae were caught in the Keiskamma estuary. Stage I larvae undergo a vertical migration at night which is markedly influenced by salinity, especially under stratified conditions. Larvae remain in the water column on the ebb tide, a behavioural pattern which effectively carried them to favourable salinities for growth and development. Stage I larvae show an association with salt front regions. The sudden decline in larval abundance from stage I to stage II downstream from the front suggests a change from a pelagic to an epibenthic existence. Later larval stages failed to appear in the plankton. However, post-larvae were caught in the estuary and a juvenile migration from the estuary to freshwater was monitored.

  13. Effects of climate change on the survival of larval cod

    NASA Astrophysics Data System (ADS)

    Kristiansen, T.; Stock, C. A.; Drinkwater, K. F.; Curchitser, E. N.

    2011-12-01

    Understanding how climate change may impact important commercial fisheries is critical for developing sustainable fisheries management strategies. In this study, we used simulations from an Earth System Model (NOAA GFDL ESM2.1) coupled with an individual-based model (IBM) for larval fish to provide a first assessment of the potential importance of climate-change driven changes in primary productivity and temperature on cod recruitment in the North Atlantic to the year 2100. ESM model output was averaged for 5 regions, each with an area of 5x5 on a latitude-longitude grid, and representing the geographic boundaries of the current cod range. The physical and environmental data were incorporated into a mechanistic IBM used to simulate the critical early phases in the life of larval fish (e.g. cod) in a changing environment. Large phytoplankton production was predicted to decrease in most regions, thereby lowering the number of meso-zooplankton in the water column. Meso-zooplankton is the most important prey item for larval cod and a reduction in their numbers have strong impacts on larval cod survival. The combination of lowered prey abundance with increased energy requirement for growth and metabolism through increased temperature had a negative impact on cod recruitment in all modeled regions of the North Atlantic. The probability of survival past the larval stages was reduced with 20-30% at all five spawning grounds by the year 2100. Together, these results suggest climate change could have significant impacts on the survival of larval cod in the North Atlantic.

  14. Swimming behavior of larval Medaka fish under microgravity

    NASA Astrophysics Data System (ADS)

    Furukawa, R.; Ijiri, K.

    Fish exhibit looping and rolling behaviors when subjected to short periods of microgravity during parabolic flight. Strain-differences in the behavioral response of adult Medaka fish ( Oryzias latipes) were reported previously, however, there have been few studies of larval fish behavior under microgravity. In the present study, we investigated whether microgravity affects the swimming behavior of larvae at various ages (0 to 20 days after hatching), using different strains: HNI-II, HO5, ha strain, and variety of different strains (variety). The preliminary experiments were done in the ground laboratory: the development of eyesight was examined using optokinetic response for the different strains. The visual acuity of larvae improved drastically during 20 days after hatching. Strain differences of response were noted for the development of their visual acuity. In microgravity, the results were significantly different from those of adult Medaka. The larval fish appeared to maintain their orientation, except that a few of them exhibited looping and rolling behavior. Further, most larvae swam normally with their backs turning toward the light source (dorsal light response, DLR), and the rest of them stayed with their abdomen touching the surface of the container (ventral substrate response, VSR). For larval stages, strain-differences and age-differences in behavior were observed, but less pronounced than with adult fish under microgravity. Our observations suggest that adaptability of larval fish to the gravitational change and the mechanism of their postural control in microgravity are more variable than in adult fish.

  15. Larval and nurse worker control of developmental plasticity and the evolution of honey bee queen-worker dimorphism

    PubMed Central

    Linksvayer, Timothy A.; Kaftanoglu, Osman; Akyol, Ethem; Blatch, Sydella; Amdam, Gro V.; Page, Robert E.

    2011-01-01

    Social evolution in honey bees has produced strong queen-worker dimorphism for plastic traits that depend on larval nutrition. The honey bee developmental program includes both larval components that determine plastic growth responses to larval nutrition and nurse components that regulate larval nutrition. We studied how these two components contribute to variation in worker and queen body size and ovary size for two pairs of honey bee lineages that show similar differences in worker body-ovary size allometry but have diverged over different evolutionary time scales. Our results indicate: that the lineages have diverged for both nurse and larval developmental components, that rapid changes in worker body-ovary allometry may disrupt queen development, and that queen-worker dimorphism arises mainly from discrete nurse-provided nutritional environments, not from a developmental switch that converts variable nutritional environments into discrete phenotypes. Both larval and nurse components have likely contributed to the evolution of queen-worker dimorphism. PMID:21696476

  16. Larval and nurse worker control of developmental plasticity and the evolution of honey bee queen-worker dimorphism.

    PubMed

    Linksvayer, T A; Kaftanoglu, O; Akyol, E; Blatch, S; Amdam, G V; Page, R E

    2011-09-01

    Social evolution in honey bees has produced strong queen-worker dimorphism for plastic traits that depend on larval nutrition. The honey bee developmental programme includes both larval components that determine plastic growth responses to larval nutrition and nurse components that regulate larval nutrition. We studied how these two components contribute to variation in worker and queen body size and ovary size for two pairs of honey bee lineages that show similar differences in worker body-ovary size allometry but have diverged over different evolutionary timescales. Our results indicate that the lineages have diverged for both nurse and larval developmental components, that rapid changes in worker body-ovary size allometry may disrupt queen development and that queen-worker dimorphism arises mainly from discrete nurse-provided nutritional environments, not from a developmental switch that converts variable nutritional environments into discrete phenotypes. Both larval and nurse components have likely contributed to the evolution of queen-worker dimorphism. PMID:21696476

  17. Evolved differences in larval social behavior mediated by novel pheromones

    PubMed Central

    Mast, Joshua D; De Moraes, Consuelo M; Alborn, Hans T; Lavis, Luke D; Stern, David L

    2014-01-01

    Pheromones, chemical signals that convey social information, mediate many insect social behaviors, including navigation and aggregation. Several studies have suggested that behavior during the immature larval stages of Drosophila development is influenced by pheromones, but none of these compounds or the pheromone-receptor neurons that sense them have been identified. Here we report a larval pheromone-signaling pathway. We found that larvae produce two novel long-chain fatty acids that are attractive to other larvae. We identified a single larval chemosensory neuron that detects these molecules. Two members of the pickpocket family of DEG/ENaC channel subunits (ppk23 and ppk29) are required to respond to these pheromones. This pheromone system is evolving quickly, since the larval exudates of D. simulans, the sister species of D. melanogaster, are not attractive to other larvae. Our results define a new pheromone signaling system in Drosophila that shares characteristics with pheromone systems in a wide diversity of insects. DOI: http://dx.doi.org/10.7554/eLife.04205.001 PMID:25497433

  18. Managing Ammonia Emissions From Screwworm Larval Rearing Media.

    PubMed

    Sagel, Agustin; Phillips, Pamela; Chaudhury, Muhammad; Skoda, Steven

    2016-02-01

    Mass production, sterilization, and release of screwworms (Cochliomyia hominivorax (Coquerel)) that were competitive in the field significantly contributed to the successful application of the sterile insect technique for eradication of screwworms from continental North America. Metabolic byproducts resulting from protein-rich diets required for larval screwworms lead to ammonia liberation, sometimes at high levels, within the mass rearing facility. Until recently a sodium polyacrylate gel bulking agent was used for the larval media and adsorbed much of the ammonia. A need to replace the gel with an environmentally "friendly" bulking agent, while not increasing ammonia levels in the rearing facility, led to a series of experiments with the objective of developing procedures to reduce ammonia emissions from the larval media bulked with cellulose fiber. Additives of ammonia-converting bacteria, potassium permanganate, and Yucca schidigera Roezl ex Otrgies powder extract, previously reported to reduce ammonia levels in organic environments, were evaluated. Ammonia-converting bacteria did not have a positive effect. Addition of Y. schidigera powder extract (∼1% of total volume), potassium permanganate (∼250 ppm), and a combination of these two additives (at these same concentrations) kept ammonia at equivalent levels as when larval media was bulked with gel. Potassium permanganate also had sufficient antimicrobial properties that the use of formaldehyde in the diet was not necessary. Further testing is needed, at a mass rearing level, before full implementation into the screwworm eradication program. PMID:26468514

  19. Remotely Sensing Larval Population Dynamics of Rice Field Anophelines

    NASA Technical Reports Server (NTRS)

    Beck, Louisa R.; Dister, Sheri W.; Wood, Byron L.; Washino, Robert K.

    1997-01-01

    The primary objective of both studies was to determine if RS and GIS techniques could be used to distinguish between high and low larval-producing rice fields in California. Results of the first study suggested that early-season green-up and proximity to livestock pastures were positively correlated with high larval abundance. Based on the early-season spectral differences between high and low larval-producing fields, it appeared that canopy development and tillering influenced mosquito habitat quality. At that time, rice fields consisted of a mixture of plants and water, a combination that allowed An. freeborni females to lay eggs in partial sunlight, protected from both predators and wind. This established a population earlier in the season than in other, 'less-green' fields where tillering and plant emergence was too minimal for ovipositioning. The study also indicated the importance of the distance that a mosquito would have to fly in order to take a bloodmeal prior to ovipositing. These associations were fully explored in an expanded study two years later. The second study confirmed the positive relationship between early season canopy development and larval abundance, and also demonstrated the relationship between abundance and distance-to-pasture. The association between greenness (as measured using NDVI), distance-to-pasture, and abundance is illustrated. The second study also indicated the siginificance of the landscape context of rice fields for larval production. Fields that included opportunities for feeding and resting within the flight range of the mosquito had higher abundances than did fields that were in a homogeneous rice area.

  20. The ortholog of human solute carrier family 35 member B1 (UDP-galactose transporter-related protein 1) is involved in maintenance of ER homeostasis and essential for larval development in Caenorhabditis elegans

    PubMed Central

    Dejima, Katsufumi; Murata, Daisuke; Mizuguchi, Souhei; Nomura, Kazuko H.; Gengyo-Ando, Keiko; Mitani, Shohei; Kamiyama, Shin; Nishihara, Shoko; Nomura, Kazuya

    2009-01-01

    Although the solute carrier 35B1 (SLC35B1) is evolutionarily conserved, its functions in metazoans remain unknown. To elucidate its function, we examined developmental roles of an SLC35B1 family gene (HUT-1: homolog of UDP-Gal transporter) in Caenorhabditis elegans. We isolated a deletion mutant of the gene and characterized phenotypes of the mutant and hut-1 RNAi-treated worms. GFP-HUT-1 reporter analysis was performed to examine gene expression patterns. We also tested whether several nucleotide sugar transporters can compensate for hut-1 deficiency. The hut-1 deletion mutant and RNAi worms showed larval growth defect and lethality with disrupted intestinal morphology. Inactivation of hut-1 induced chronic endoplasmic reticulum (ER) stress, and hut-1 showed genetic interactions with the atf-6, pek-1, and ire-1 genes involved in unfolded protein response signaling. ER ultrastructure and ER marker distribution in hut-1-deficient animals showed that HUT-1 is required for maintenance of ER structure. Reporter analysis revealed that HUT-1 is an ER protein ubiquitously expressed in tissues, including the intestine. Lethality and the ER stress phenotype of the mutant were rescued with the human hut-1 ortholog UGTrel1. These results indicate important roles for hut-1 in development and maintenance of ER homeostasis in C. elegans. PMID:19270184

  1. Larval intraspecific competition for food in the European grapevine moth Lobesia botrana.

    PubMed

    Thiéry, D; Monceau, K; Moreau, J

    2014-08-01

    Effective pest management with lower amounts of pesticides relies on accurate prediction of insect pest growth rates. Knowledge of the factors governing this trait and the resulting fitness of individuals is thus necessary to refine predictions and make suitable decisions in crop protection. The European grapevine moth, Lobesia botrana, the major pest of grapes in Europe, is responsible for huge economic losses. Larvae very rarely leave the grape bunch on which they were oviposited and thus cannot avoid intraspecific competition. In this study, we determined the impact of intraspecific competition during the larval stage on development and adult fitness in this species. This was tested by rearing different numbers of larvae on an artificial diet and measuring developmental and reproductive life history traits. We found that intraspecific competition during larval development has a slight impact on the fitness of L. botrana. The principal finding of this work is that larval density has little effect on the life history traits of survivors. Thus, the timing of eclosion, duration of subsequent oviposition, fecundity appears to be more uniform in L. botrana than in other species. The main effect of larval crowding was a strong increase of larval mortality at high densities whereas the probability of emergence, sex ratio, pupal mass, fecundity and longevity of mated females were not affected by larval crowding. Owing to increased larval mortality at high larval densities, we hypothesized that mortality of larvae at high densities provided better access to food for the survivors with the result that more food was available per capita and there were no effect on fitness of survivors. From our results, larval crowding alters the reproductive capacity of this pest less than expected but this single factor should now be tested in interaction with limited resources in the wild. PMID:24788023

  2. Density-dependent effects in experimental larval populations of Anopheles arabiensis (Diptera: Culicidae) can be negative, neutral, or overcompensatory depending on density and diet levels.

    PubMed

    Gilles, J R L; Lees, R S; Soliban, S M; Benedict, M Q

    2011-03-01

    Anopheles arabiensis Patton (Diptera: Culicidae) larvae were reared from hatching to the adult stage in the laboratory under a range of diet and larval concentrations using a factorial design. The range circumscribed most of the larval densities and diet concentrations that would allow larval growth and survival using the particular diet formulation and water volume we tested. We determined how these variables affected three outcomes, as follows: larval development rate, survival, and wing length. As has been reported previously, negative density dependence of survival as a function of increased larval density was the prevalent effect on all outcomes when diet was limiting. When diet was not limiting, density dependence was not observed, and three cases of overcompensatory survival were seen. We discuss these results in the context of diet and larval densities for mass rearing and the effect of larval competition on control strategies. PMID:21485365

  3. Low dose exposure to Bisphenol A alters development of gonadotropin-releasing hormone 3 neurons and larval locomotor behavior in Japanese Medaka.

    PubMed

    Inagaki, T; Smith, N; Lee, E K; Ramakrishnan, S

    2016-01-01

    Accumulating evidence indicates that chronic low dose exposure to Bisphenol A (BPA), an endocrine disruptor, may disrupt normal brain development and behavior mediated by the gonadotropin-releasing hormone (GnRH) pathways. While it is known that GnRH neurons in the hypothalamus regulate reproductive physiology and behavior, functional roles of extra-hypothalamic GnRH neurons remain unclear. Furthermore, little is known whether BPA interacts with extra-hypothalamic GnRH3 neural systems in vulnerable developing brains. Here we examined the impact of low dose BPA exposure on the developing GnRH3 neural system, eye and brain growth, and locomotor activity in transgenic medaka embryos and larvae with GnRH3 neurons tagged with GFP. Fertilized eggs were collected daily and embryos/larvae were chronically exposed to 200ng/ml of BPA, starting at 1 day post fertilization (dpf). BPA significantly increased fluorescence intensity of the GnRH3-GFP neural population in the terminal nerve (TN) of the forebrain at 3dpf, but decreased the intensity at 5dpf, compared with controls. BPA advanced eye pigmentation without affecting eye and brain size development, and accelerated times to hatch. Following chronic BPA exposure, 20dpf larvae showed suppression of locomotion, both in distance covered and speed of movement (47% and 43% reduction, respectively). BPA-induced hypoactivity was accompanied by decreased cell body sizes of individual TN-GnRH3 neurons (14% smaller than those of controls), but not of non-GnRH3 neurons. These novel data demonstrate complex neurobehavioral effects of BPA on the development of extra-hypothalamic GnRH3 neurons in teleost fish. PMID:26687398

  4. New threshold temperatures for the development of a North American diamondback moth (Lepidoptera: Plutellidae) population and its larval parasitoid, Diadegma insulare (Hymenoptera: Ichneumonidae).

    PubMed

    Bahar, M H; Soroka, J J; Grenkow, L; Dosdall, L M

    2014-10-01

    The currently accepted lower threshold temperature for the development of diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), the world's most destructive insect pest of cruciferous crops, is around 6.0°C, and there is no known upper threshold temperature. Neither are there established threshold temperatures for diamondback moth's major natural enemy, Diadegma insulare (Hymenoptera: Ichneumonidae). Laboratory studies were undertaken to determine the survival and development of a North American diamondback moth population and its parasitoid D. insulare at 20 constant temperatures ranging from 2.0 to 38.0°C. Diamondback moth completed development from second instar to adult within a temperature range of 4.0-37°C, and D. insulare completed its life cycle from egg to adult within a temperature range of 4.0-33°C. The developmental data were fitted into one linear and four nonlinear models. Using goodness-of-fit and the ability to estimate parameters of biological significance as selection criteria, the Wang model was the most acceptable among the nonlinear models to describe the relationship between temperature and development of both species. According to this model, the lower and upper threshold temperatures for diamondback moth were 2.1 and 38.0°C, respectively, and for D. insulare they were 2.1 and 34.0°C, respectively. Based on the Degree Day model, diamondback moth required 143 d above the lower threshold of 4.23°C to complete the life cycle, while D. insulare required 286 d above the lower threshold of 2.57°C. This study suggests that temperatures during the crop-growing seasons in North America are not limiting factors for development of either diamondback moth or D. insulare. PMID:25259698

  5. A High-Throughput Method for the Analysis of Larval Developmental Phenotypes in Caenorhabditis elegans

    PubMed Central

    Olmedo, María; Geibel, Mirjam; Artal-Sanz, Marta; Merrow, Martha

    2015-01-01

    Caenorhabditis elegans postembryonic development consists of four discrete larval stages separated by molts. Typically, the speed of progression through these larval stages is investigated by visual inspection of the molting process. Here, we describe an automated method to monitor the timing of these discrete phases of C. elegans maturation, from the first larval stage through adulthood, using bioluminescence. The method was validated with a lin-42 mutant strain that shows delayed development relative to wild-type animals and with a daf-2 mutant that shows an extended second larval stage. This new method is inherently high-throughput and will finally allow dissecting the molecular machinery governing the speed of the developmental clock, which has so far been hampered by the lack of a method suitable for genetic screens. PMID:26294666

  6. Foraging characteristics of larval bluegill sunfish and larval longear sunfish in the Kanawha River, West Virginia

    USGS Publications Warehouse

    Rider, S.J.; Margraf, F.J.

    1998-01-01

    We determined spatial and temporal foraging characteristics of larval bluegill sunfish (Lepomis macrochirus) and longear sunfish (Lepomis megalotis) in the upper Kanawha River, West Virginia during the summer of 1989. Stomach contents were examined among habitat types (i.e., main channel, main-channel border, and shoreline habitats) and depth (surface, middle, and bottom). Diet of larval bluegill sunfish was dominated by Chironomidae, temporally and spatially. Chironomidae dominated larval longear sunfish diet in main channel and main-channel border collections from all three depths. However, along the shoreline, larval longear sunfish diet was dominated by Cladocera.

  7. Soundscapes and Larval Settlement: Larval Bivalve Responses to Habitat-Associated Underwater Sounds.

    PubMed

    Eggleston, David B; Lillis, Ashlee; Bohnenstiehl, DelWayne R

    2016-01-01

    We quantified the effects of habitat-associated sounds on the settlement response of two species of bivalves with contrasting habitat preferences: (1) Crassostrea virginicia (oyster), which prefers to settle on other oysters, and (2) Mercenaria mercenaria (clam), which settles on unstructured habitats. Oyster larval settlement in the laboratory was significantly higher when exposed to oyster reef sound compared with either off-reef or no-sound treatments. Clam larval settlement did not vary according to sound treatments. Similar to laboratory results, field experiments showed that oyster larval settlement in "larval housings" suspended above oyster reefs was significantly higher compared with off-reef sites. PMID:26610967

  8. The number of zoeal stages in larval development of Nihonotrypaea petalura (Stimpson, 1860) (Decapoda: Axiidea: Callianassidae) from Russian waters of the Sea of Japan.

    PubMed

    Kornienko, Elena S; Korn, Olga M; Golubinskaya, Darya D

    2015-01-01

    Zoeal stages of the mud shrimp Nihonotrypaea petalura (Stimpson, 1860) (Decapoda: Axiiidea: Callianassidae) inhabiting Peter the Great Bay (Sea of Japan) is described and illustrated from the larvae reared in the laboratory individually. The development included seven zoeal stages before molting to the megalopa. At 22-23°C the first megalopa was attained 26 days after hatching. A range of the number of zoeal stages in the family Callianassidae is analyzed. The possibility of variation of the number of zoeal stages of burrowing shrimps in different populations of the same species and/or under different laboratory conditions is discussed. PMID:25781132

  9. Linking River Morphology to Larval Drift of an Endangered Sturgeon

    NASA Astrophysics Data System (ADS)

    Bazzetta, L.; Jacobson, R. B.; Braaten, P. J.; Elliott, C. M.; Reuter, J. M.

    2009-12-01

    Computational models developed to calculate longitudinal advection and dispersion of contaminants in rivers have potential application in predicting larval drift. A critical component of this family of models is the longitudinal dispersion coefficient which parameterizes the processes that retain and distribute a contaminant along the river. Here we evaluate the potential for longitudinal dispersion coefficients to characterize larval drift of the endangered pallid sturgeon (Scaphirhynchus albus) in various segments of the free-flowing Missouri River ranging from Missouri to Montana. We randomly selected transects of acoustic Doppler current profiler (ADCP) flow velocity data from reach-scale datasets that were collected in the Missouri River from 2002-2008 under comparable discharge conditions. We used previously developed equations (Kim and others, 2007) to calculate a one-dimensional longitudinal dispersion coefficient for each ADCP transect. We compared the statistical distributions of these coefficients for 2 to 6 reaches chosen from each of six geomorphic segments of the Missouri. Distributional patterns indicate that dispersion coefficients relate to observed variation in hydrology and geomorphology of the channel at the segment scale. Although one-dimensional dispersion analysis demonstrates potential as a tool for estimating pallid sturgeon larval drift and habitat suitability in unchannelized portions of the Missouri River, the large spatial variation in calculated dispersion coefficients resulting from river-training structures (wing dikes) in the Lower Missouri complicates selection of appropriate values. Recent data indicating that pallid sturgeon larvae occur in greater concentration in the thalweg indicate that the majority of larvae may bypass these structures and their associated retentive eddies. A two-dimensional space-averaged dispersion calculation and analysis may more accurately characterize the potential drift times and distances of larval

  10. A hemocyte-expressed fibrinogen-related protein gene (LvFrep) from the shrimp Litopenaeus vannamei: Expression analysis after microbial infection and during larval development.

    PubMed

    Coelho, Jaqueline da Rosa; Barreto, Cairé; Silveira, Amanda da Silva; Vieira, Graziela Cleusa; Rosa, Rafael Diego; Perazzolo, Luciane Maria

    2016-09-01

    Fibrinogen-related proteins (FREPs) comprise a large family of microbial recognition proteins involved in many biological functions in both vertebrate and invertebrate animals. By taking advantage of publicly accessible databases, we have identified a FREP-like homolog in the most cultivated penaeid shrimp, Litopenaeus vannamei (LvFrep). The obtained sequence showed a conserved fibrinogen-related domain (FReD) and displayed significant similarities to FREP-like proteins from other invertebrates and to ficolins from crustaceans. The expression of LvFrep appeared to be limited to circulating hemocytes. Interestingly, LvFrep gene expression was induced in shrimp hemocytes only in response to a Vibrio infection but not to the White spot syndrome virus (WSSV). Moreover, LvFrep transcript levels were detected early in fertilized eggs, suggesting the participation of this immune-related gene in the antimicrobial defenses during shrimp development. PMID:27380968

  11. Preliminary observations on the effects of vector-averaged gravity on the embryonic and larval development of the gastropod mollusk, Ilyanassa obsoleta Stimpson

    NASA Technical Reports Server (NTRS)

    Conrad, G. W.; Stephens, A. P.; Conrad, A. H.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    Fertilized eggs of Ilyanassa obsoleta Stimpson were collected immediately after their deposition in egg capsules. Unopened egg capsules then were affixed to glass slides, and incubated either statically (controls) or on a clinostat (experimentals). After incubation for 9-14 days, hatching occurred sooner and in a higher percentage of clinostated capsules than in controls. Embryos that hatched while undergoing clinostat incubation were abnormal in morphology, whereas other embryos present in non-hatched capsules in the same tubes appeared normal, as did embryos in the control tubes. Although the results are compatible with a conclusion that vector-averaged gravity in the experimental tubes caused the altered development, some other aspects of how the incubations were done may have contributed to the differences between the control and experimental results.

  12. Detecting larval export from marine reserves

    PubMed Central

    Pelc, R. A.; Warner, R. R.; Gaines, S. D.; Paris, C. B.

    2010-01-01

    Marine reserve theory suggests that where large, productive populations are protected within no-take marine reserves, fished areas outside reserves will benefit through the spillover of larvae produced in the reserves. However, empirical evidence for larval export has been sparse. Here we use a simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine reserves across a range of reserve sizes and larval dispersal scales. Results suggest that, given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort. However, the proportional increase in recruitment at sites outside reserves is typically small, particularly for species with long-distance (on the order of hundreds of kilometers) larval dispersal distances, making it very difficult to detect in field studies. Enhanced recruitment due to export may be detected by sampling several sites at an appropriate range of distances from reserves or at sites downcurrent of reserves in systems with directional dispersal. A review of existing empirical evidence confirms the model's suggestion that detecting export may be difficult without an exceptionally large differential in production, short-distance larval dispersal relative to reserve size, directional dispersal, or a sampling scheme that encompasses a broad range of distances from the reserves. PMID:20181570

  13. A Caenorhabditis elegans type I TGF beta receptor can function in the absence of type II kinase to promote larval development.

    PubMed

    Gunther, C V; Georgi, L L; Riddle, D L

    2000-08-01

    The daf-4 gene encodes a type II bone morphogenetic protein receptor in Caenorhabditis elegans that regulates dauer larva formation, body size and male tail patterning. The putative type I receptor partner for DAF-4 in regulating dauer larva formation is DAF-1. Genetic tests of the mechanism of activation of these receptors show that DAF-1 can signal in the absence of DAF-4 kinase activity. A daf-1 mutation enhances dauer formation in a daf-4 null background, whereas overexpression of daf-1 partially rescues a daf-4 mutant. DAF-1 alone cannot fully compensate for the loss of DAF-4 activity, indicating that nondauer development normally results from the activities of both receptors. DAF-1 signaling in the absence of a type II kinase is unique in the type I receptor family. The activity may be an evolutionary remnant, owing to daf-1's origin near the type I/type II divergence, or it may be an innovation that evolved in nematodes. daf-1 and daf-4 promoters both mediated expression of green fluorescent protein in the nervous system, indicating that a DAF-1/DAF-4 receptor complex may activate a neuronal signaling pathway. Signaling from a strong DAF-1/DAF-4 receptor complex or a weaker DAF-1 receptor alone may provide larvae with more precise control of the dauer/nondauer decision in a range of environmental conditions. PMID:10887089

  14. Larval exposure to 4-nonylphenol and 17β-estradiol affects physiological and behavioral development of seawater adaptation in Atlantic salmon smolts

    USGS Publications Warehouse

    Lerner, Darrren T.; Bjornsson, Bjorn Thrandur; McCormick, Stephen D.

    2007-01-01

    Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon yolk-sac larvae to waterborne 10 or 100 μg L-1 NP (NP-L or NP-H, respectively), 2 μg L-1 17β-estradiol (E2), or vehicle, for 21 days to investigate their effects on smolt physiology and behavior 1 year later. NP-H caused approximately 50% mortality during exposure, 30 days after exposure, and 60 days after exposure. Mortality rates of NP-L and E2 fish were not affected until 60 days after treatment, when they were 4-fold greater than those of controls. Treatment with NP-L or E2 as yolk-sac larvae decreased gill sodium-potassium-activated adenosine triphosphatase (Na+,K+-ATPase) activity and seawater (SW) tolerance during smolt development, 1 year after exposure. Exposure to NP-L and E2 resulted in a latency to enter SW and reduced preference for SW approximately 2- and 5-fold, respectively. NP-L-exposed fish had 20% lower plasma insulin-like growth factor I (IGF-I) levels and 35% lower plasma triiodothyronine (T3). Plasma growth hormone and thyroxine (T4) were unaffected. Exposure to E2 did not affect plasma levels of IGF-I, GH, T3, or T4. Both treatment groups exhibited increased plasma cortisol and decreased osmoregulatory capacity in response to a handling stressor. These results suggest that early exposure to environmentally relevant concentrations of NP, and other estrogenic compounds, can cause direct and delayed mortalities and that this exposure can have long term, “organizational” effects on life-history events in salmonids.

  15. Larval development and settling of Macoma balthica in a large-scale mesocosm experiment at different fCO2 levels

    NASA Astrophysics Data System (ADS)

    Jansson, A.; Lischka, S.; Boxhammer, T.; Schulz, K. G.; Norkko, J.

    2015-12-01

    Anthropogenic carbon dioxide (CO2) emissions are causing severe changes in the global inorganic carbon balance of the oceans. Associated ocean acidification is expected to impose a major threat to marine ecosystems worldwide, and it is also expected to be amplified in the Baltic Sea where the system is already at present exposed to relatively large natural seasonal and diel pH fluctuations. The response of organisms to future ocean acidification has primarily been studied in single-species experiments, whereas the knowledge of community-wide responses is still limited. To study responses of the Baltic Sea pelagic community to a range of future CO2-scenarios, six ∼ 55 m3 pelagic mesocosms were deployed in the northern Baltic Sea in June 2012. In this specific study we focused on the tolerance, development and subsequent settlement process of the larvae of the benthic key-species Macoma balthica when exposed to different levels of future CO2. We found that the settling of M. balthica was delayed along the increasing CO2 gradient of the mesocosms. Also, when exposed to increasing CO2 levels larvae settled at a larger size, indicating a developmental delay. With on-going climate change, both the frequency and extent of regularly occurring high CO2 conditions is likely to increase, and a permanent pH decrease will likely occur. The strong impact of increasing CO2 levels on early-stage bivalves is alarming as these stages are crucial for sustaining viable populations, and a failure in their recruitment would ultimately lead to negative effects on the population.

  16. Larval exposure to 4-nonylphenol and 17beta-estradiol affects physiological and behavioral development of seawater adaptation in Atlantic salmon smolts.

    PubMed

    Lerner, Darren T; Björnsson, Björn Thrandur; McCormick, Stephen D

    2007-06-15

    Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon yolk-sac larvae to waterborne 10 or 100 microg L(-1) NP (NP-L or NP-H, respectively), 2 microg L(-1) 17beta-estradiol (E2), or vehicle, for 21 days to investigate their effects on smolt physiology and behavior 1 year later. NP-H caused approximately 50% mortality during exposure, 30 days after exposure, and 60 days after exposure. Mortality rates of NP-L and E2 fish were not affected until 60 days after treatment, when they were 4-fold greater than those of controls. Treatment with NP-L or E2 as yolk-sac larvae decreased gill sodium-potassium-activated adenosine triphosphatase (Na+,K(+)-ATPase) activity and seawater (SW) tolerance during smolt development, 1 year after exposure. Exposure to NP-L and E2 resulted in a latency to enter SW and reduced preference for SW approximately 2- and 5-fold, respectively. NP-L-exposed fish had 20% lower plasma insulin-like growth factor I (IGF-I) levels and 35% lower plasma triiodothyronine (T3). Plasma growth hormone and thyroxine (T4) were unaffected. Exposure to E2 did not affect plasma levels of IGF-I, GH, T3, or T4. Both treatment groups exhibited increased plasma cortisol and decreased osmoregulatory capacity in response to a handling stressor. These results suggest that early exposure to environmentally relevant concentrations of NP, and other estrogenic compounds, can cause direct and delayed mortalities and that this exposure can have long-term, "organizational" effects on life-history events in salmonids. PMID:17626455

  17. Immunoregulation in larval Echinococcus multilocularis infection.

    PubMed

    Wang, J; Gottstein, B

    2016-03-01

    Alveolar echinococcosis (AE) is a clinically very severe zoonotic helminthic disease, characterized by a chronic progressive hepatic damage caused by the continuous proliferation of the larval stage (metacestode) of Echinococcus multilocularis. The proliferative potential of the parasite metacestode tissue is dependent on the nature/function of the periparasitic immune-mediated processes of the host. Immune tolerance and/or down-regulation of immunity are a marked characteristic increasingly observed when disease develops towards its chronic (late) stage of infection. In this context, explorative studies have clearly shown that T regulatory (Treg) cells play an important role in modulating and orchestrating inflammatory/immune reactions in AE, yielding a largely Th2-biased response, and finally allowing thus long-term parasite survival, proliferation and maturation. AE is fatal if not treated appropriately, but the current benzimidazole chemotherapy is far from optimal, and novel options for control are needed. Future research should focus on the elucidation of the crucial immunological events that lead to anergy in AE, and focus on providing a scientific basis for the development of novel and more effective immunotherapeutical options to support cure AE by abrogating anergy, anticipating also that a combination of immuno- and chemotherapy could provide a synergistic therapeutical effect. PMID:26536823

  18. Mosquito larval source management for controlling malaria

    PubMed Central

    Tusting, Lucy S; Thwing, Julie; Sinclair, David; Fillinger, Ulrike; Gimnig, John; Bonner, Kimberly E; Bottomley, Christian; Lindsay, Steven W

    2015-01-01

    Background Malaria is an important cause of illness and death in people living in many parts of the world, especially sub-Saharan Africa. Long-lasting insecticide treated bed nets (LLINs) and indoor residual spraying (IRS) reduce malaria transmission by targeting the adult mosquito vector and are key components of malaria control programmes. However, mosquito numbers may also be reduced by larval source management (LSM), which targets mosquito larvae as they mature in aquatic habitats. This is conducted by permanently or temporarily reducing the availability of larval habitats (habitat modification and habitat manipulation), or by adding substances to standing water that either kill or inhibit the development of larvae (larviciding). Objectives To evaluate the effectiveness of mosquito LSM for preventing malaria. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; CABS Abstracts; and LILACS up to 24 October 2012. We handsearched the Tropical Diseases Bulletin from 1900 to 2010, the archives of the World Health Organization (up to 11 February 2011), and the literature database of the Armed Forces Pest Management Board (up to 2 March 2011). We also contacted colleagues in the field for relevant articles. Selection criteria We included cluster randomized controlled trials (cluster-RCTs), controlled before-and-after trials with at least one year of baseline data, and randomized cross-over trials that compared LSM with no LSM for malaria control. We excluded trials that evaluated biological control of anopheline mosquitoes with larvivorous fish. Data collection and analysis At least two authors assessed each trial for eligibility. We extracted data and at least two authors independently determined the risk of bias in the included studies. We resolved all disagreements through discussion with a third author. We analyzed the data using Review Manager 5 software

  19. Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus.

    PubMed

    Bara, Jeffrey; Rapti, Zoi; Cáceres, Carla E; Muturi, Ephantus J

    2015-01-01

    Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced. PMID:25951173

  20. Life History Changes in Coral Fluorescence and the Effects of Light Intensity on Larval Physiology and Settlement in Seriatopora hystrix

    PubMed Central

    Roth, Melissa S.; Fan, Tung-Yung; Deheyn, Dimitri D.

    2013-01-01

    Fluorescence is common in both coral adult and larval stages, and is produced by fluorescent proteins that absorb higher energy light and emit lower energy light. This study investigated the changes of coral fluorescence in different life history stages and the effects of parental light environment on larval fluorescence, larval endosymbiotic dinoflagellate abundance, larval size and settlement in the brooding coral Seriatopora hystrix. Data showed that coral fluorescence changed during development from green in larvae to cyan in adult colonies. In larvae, two green fluorescent proteins (GFPs) co-occur where the peak emission of one GFP overlaps with the peak excitation of the second GFP allowing the potential for energy transfer. Coral larvae showed great variation in GFP fluorescence, dinoflagellate abundance, and size. There was no obvious relationship between green fluorescence intensity and dinoflagellate abundance, green fluorescence intensity and larval size, or dinoflagellate abundance and larval size. Larvae of parents from high and low light treatments showed similar green fluorescence intensity, yet small but significant differences in size, dinoflagellate abundance, and settlement. The large variation in larval physiology combined with subtle effects of parental environment on larval characteristics seem to indicate that even though adult corals produce larvae with a wide range of physiological capacities, these larvae can still show small preferences for settling in similar habitats as their parents. These data highlight the importance of environmental conditions at the onset of life history and parent colony effects on coral larvae. PMID:23544072

  1. Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus

    PubMed Central

    Bara, Jeffrey; Rapti, Zoi; Cáceres, Carla E.; Muturi, Ephantus J.

    2015-01-01

    Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced. PMID:25951173

  2. Larval history influences post-metamorphic condition in a coral-reef fish.

    PubMed

    Hamilton, Scott L

    2008-12-01

    Upon settlement, many fishes undergo an energetically costly metamorphic period that requires substantial nutritional reserves. Larval growth and the accumulation of lipids prior to metamorphosis are likely to influence growth and survival following this critical period. On the Caribbean island of St. Croix, I investigated relationships between larval growth, early life-history characteristics, and post-metamorphic lipid content in the bluehead wrasse Thalassoma bifasciatum. Lipid reserves remaining after metamorphosis were positively related (r2 = 0.62) to the width of the metamorphic band; thus, this otolith-derived trait may be used to estimate the condition at emergence of survivors collected at some later time. In contrast, pelagic larval duration, average larval growth, and otolith size at settlement were negatively related to post-metamorphic lipid content. Interestingly, the trend for slower growth among fish in good condition was not consistent over the entire pelagic larval duration. Analyses of daily larval growth histories indicated that fish with high lipid reserves grew rapidly in the last week prior to settlement, but relatively slowly during the early phases of larval life; those emerging with low lipid concentrations, however, displayed strikingly opposite patterns. These contrasting patterns of growth and energy storage were consistent at two sites and over three recruitment events. Otolith chemistry data suggested that differences in growth histories and body condition were consistent with the hypothesis of larval development in distinct oceanic environments (characterized by Pb concentration); but, within a water mass, differences reflected life-history trade-offs between growth and energy storage. The results have implications for understanding the processes driving juvenile survival, which may be condition dependent. PMID:18836749

  3. Evaluation of Human Attachment by Larval Amblyomma maculatum (Acari: Ixodidae).

    PubMed

    Portugal, José Santos; Goddard, Jerome

    2016-03-01

    The tick, Amblyomma maculatum Koch (Gulf Coast tick), has recently been shown to be an important disease vector of both medical and veterinary concern. Although much is known about the behavior and ecology of adults, little is known of the immatures. Larval feeding on humans has never been demonstrated (and thus, there are no collection records from humans). In this experiment, 10 larval A. maculatum, Amblyomma americanum (L.) (a positive control), and Dermacentor variabilis (Say) (a negative control), were applied to both forearms of 10 human volunteers (five male, five female). Ticks were placed in plastic caps and secured to skin with medical-grade adhesive tape, and volunteers remained sedentary during the experiment. After 15 min, caps were removed, and attachment was determined using fine-tipped forceps. Any A. maculatum that were attached were then removed and subsequently examined microscopically to verify identification. In total, 34 ticks attached to the subjects, including 11 A. maculatum (5.5%), 23 A. americanum (11.5%), and no D. variabilis. Amblyomma maculatum attached to six volunteers, and no apparent association between gender and attachment rate was noted. No skin lesions developed in the human volunteers bit by A. maculatum. This is the first report of larval A. maculatum attaching to humans, and is significant in that Rickettsia parkeri, a human pathogen vectored by this species, has recently been reported to be transmitted transovarially. If A. maculatum are infected as larvae, they could potentially transmit R. parkeri to people. PMID:26576936

  4. Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis

    EPA Science Inventory

    Amphibian model species Xenopus tropicalis is currently being utilized by EPA in the development of a standardized in vivo reproductive toxicity assay. Perturbations to the hypothalamic-pituitary-gonadal axis from exposure to endocrine disrupting compounds during larval develop...

  5. Enhancement of Larval RNAi Efficiency by Over-expressing Argonaute2 in Bombyx mori

    PubMed Central

    Li, Zhiqian; Zeng, Baosheng; Ling, Lin; Xu, Jun; You, Lang; Aslam, Abu F.M.; Tan, Anjiang; Huang, Yongping

    2015-01-01

    RNA interference has been described as a powerful genetic tool for gene functional analysis and a promising approach for pest management. However, RNAi efficiency varies significantly among insect species due to distinct RNAi machineries. Lepidopteran insects include a large number of pests as well as model insects, such as the silkworm, Bombyx mori. However, only limited success of in vivo RNAi has been reported in lepidoptera, particularly during the larval stages when the worms feed the most and do the most harm to the host plant. Enhancing the efficiency of larval RNAi in lepidoptera is urgently needed to develop RNAi-based pest management strategies. In the present study, we investigate the function of the conserved RNAi core factor, Argonaute2 (Ago2), in mediating B. mori RNAi efficiency. We demonstrate that introducing BmAgo2 dsRNA inhibits the RNAi response in both BmN cells and embryos. Furthermore, we establish several transgenic silkworm lines to assess the roles of BmAgo2 in larval RNAi. Over-expressing BmAgo2 significantly facilitated both dsRNA-mediated larval RNAi when targeting DsRed using dsRNA injection and shRNA-mediated larval RNAi when targeting BmBlos2 using transgenic shRNA expression. Our results show that BmAgo2 is involved in RNAi in B. mori and provides a promising approach for improving larval RNAi efficiency in B. mori and in lepidopteran insects in general. PMID:25561900

  6. Distribution, Health, and Development of Larval and Juvenile Lost River and Shortnose Suckers in the Williamson River Delta Restoration Project and Upper Klamath Lake, Oregon: 2008 Annual Data Summary

    USGS Publications Warehouse

    Burdick, Summer M.; Ottinger, Christopher; Brown, Daniel T.; VanderKooi, Scott P.; Robertson, Laura; Iwanowicz, Deborah

    2009-01-01

    Federally endangered Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris were once abundant throughout their range but populations have declined; they have been extirpated from several lakes, and may no longer reproduce in others. Poor recruitment into the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species, and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable rearing habitat. Within Upper Klamath Lake, a lack of marshes also may allow larval suckers to be swept from suitable rearing areas downstream into the seasonally anoxic waters of the Keno Reservoir. The Nature Conservancy (TNC) flooded about 3,600 acres to the north of the Williamson River mouth (Tulana Unit) in October 2007, and about 1,400 acres to the south and east of the Williamson River mouth (Goose Bay Unit) a year later, to retain larval suckers in Upper Klamath Lake, create nursery habitat for suckers, and improve water quality. In collaboration with TNC, the Bureau of Reclamation, and Oregon State University, we began a long-term collaborative research and monitoring program in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. Our approach includes two equally important aspects. One component is to describe habitat use and colonization processes by larval and juvenile suckers and non-sucker fish species. The second is to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report contains a summary of the first year of data collected as a part of this monitoring effort.

  7. Anopheline Larval Habitats Seasonality and Species Distribution: A Prerequisite for Effective Targeted Larval Habitats Control Programmes

    PubMed Central

    Kweka, Eliningaya J.; Zhou, Guofa; Munga, Stephen; Lee, Ming-Chieh; Atieli, Harrysone E.; Nyindo, Mramba; Githeko, Andrew K.; Yan, Guiyun

    2012-01-01

    Background Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya. Methods and Findings A total of 51 aquatic habitats positive for anopheline larvae were surveyed and visited once a week for a period of 85 weeks in succession. Habitats were selected and identified. Mosquito larval species, physico-chemical parameters, habitat size, grass cover, crop cycle and distance to nearest house were recorded. Polymerase chain reaction revealed that An. gambiae s.l was the most dominant vector species comprised of An.gambiae s.s (77.60%) and An.arabiensis (18.34%), the remaining 4.06% had no amplification by polymerase chain reaction. Physico-chemical parameters and habitat size significantly influenced abundance of An. gambiae s.s (P = 0.024) and An. arabiensis (P = 0.002) larvae. Further, larval species abundance was influenced by crop cycle (P≤0.001), grass cover (P≤0.001), while distance to nearest houses significantly influenced the abundance of mosquito species larvae (r = 0.920;P≤0.001). The number of predator species influenced mosquito larval abundance in different habitat types. Crop weeding significantly influenced with the abundance of An.gambiae s.l (P≤0.001) when preceded with fertilizer application. Significantly higher anopheline larval abundance was recorded in habitats in pasture compared to farmland (P = 0.002). When habitat stability and habitat types were considered, hoof print were the most productive followed by disused goldmines. Conclusion These findings suggest that implementation of effective larval control

  8. Egg hatching, larval movement and larval survival of the malaria vector Anopheles gambiae in desiccating habitats

    PubMed Central

    Koenraadt, Constantianus JM; Paaijmans, Krijn P; Githeko, Andrew K; Knols, Bart GJ; Takken, Willem

    2003-01-01

    Background Although the effects of rainfall on the population dynamics of the malaria vector Anopheles gambiae have been studied in great detail, the effects of dry periods on its survival remain less clear. Methods The effects of drying conditions were simulated by creating desiccated habitats, which consisted of trays filled with damp soil. Experiments were performed in these trays to (i) test the ability of An. gambiae sensu stricto eggs to hatch on damp soil and for larvae to reach an artificial breeding site at different distances of the site of hatching and (ii) to record survival of the four larval stages of An. gambiae s.s. when placed on damp soil. Results Eggs of An. gambiae s.s. hatched on damp soil and emerging larvae were capable of covering a distance of up to 10 cm to reach surface water enabling further development. However, proportions of larvae reaching the site decreased rapidly with increasing distance. First, second and third-instar larvae survived on damp soil for an estimated period of 64, 65 and 69 hrs, respectively. Fourth-instar larvae survived significantly longer and we estimated that the maximum survival time was 113 hrs. Conclusion Short-term survival of aquatic stages of An. gambiae on wet soil may be important and adaptive when considering the transient nature of breeding sites of this species in sub-Saharan Africa. In addition, the results suggest that, for larval vector control methods to be effective, habitats should remain drained for at least 5 days to kill all larvae (e.g. in rice fields) and habitats that recently dried up should be treated as well, if larvicidal agents are applied. PMID:12919636

  9. Oyster larval transport in coastal Alabama: Dominance of physical transport over biological behavior in a shallow estuary

    NASA Astrophysics Data System (ADS)

    Kim, Choong-Ki; Park, Kyeong; Powers, Sean P.; Graham, William M.; Bayha, Keith M.

    2010-10-01

    Among the various factors affecting recruitment of marine invertebrates and fish, larval transport may produce spatial and temporal patterns of abundance that are important determinants of management strategies. Here we conducted a field and modeling study to investigate the larval transport of eastern oyster, Crassostrea virginica, in Mobile Bay and eastern Mississippi Sound, Alabama. A three-dimensional larval transport model accounting for physical transport, biological movement of larvae, and site- and larval-specific conditions was developed. A hydrodynamic model was used to simulate physical transport, and biological movement was parameterized as a function of swimming and sinking velocity of oyster larvae. Site- and larval-specific conditions, including spawning location, spawning stock size, spawning time, and larval period, were determined based on the previous studies. The model reasonably reproduced the observed gradient in oyster spat settlement and bivalve larval concentration, although the model results were less dynamic than the data, probably owing to the simplified biological conditions employed in the model. A persistent gradient decreasing from west to east in the model results at time scales of overall average, season, and each survey in 2006 suggests that the larval supply may be responsible for the corresponding gradient in oyster spat settlement observed over the past 40 years. Biological movement increased larval retention near the spawning area, thus providing a favorable condition for local recruitment of oysters. Inclusion of biological movement, however, caused little change in the overall patterns of larval transport and still resulted in a west-east gradient, presumably because of frequent destratification in the shallow Mobile Bay system.

  10. Habitat Suitability Index Models: Larval and Juvenile Red Drum

    USGS Publications Warehouse

    Buckley, Jack

    1984-01-01

    A review and synthesis of existing information were used to develop a habitat model for larval and juvenile red drum. The model is scaled to produce an index of habitat suitability between 0 (unsuitable habitat) and 1 (optimally suitable habitat) for estuarine areas along the Gulf of Mexico and Atlantic coasts. Habitat suitability indices are designed for use with habitat evaluation procedures developed by the U.S. Fish and Wildlife Service. Guidelines for model application and techniques for estimating model variables are provided.

  11. Functional genomics identifies regulators of the phototransduction machinery in the Drosophila larval eye and adult ocelli.

    PubMed

    Mishra, Abhishek Kumar; Bargmann, Bastiaan O R; Tsachaki, Maria; Fritsch, Cornelia; Sprecher, Simon G

    2016-02-15

    Sensory perception of light is mediated by specialized Photoreceptor neurons (PRs) in the eye. During development all PRs are genetically determined to express a specific Rhodopsin (Rh) gene and genes mediating a functional phototransduction pathway. While the genetic and molecular mechanisms of PR development is well described in the adult compound eye, it remains unclear how the expression of Rhodopsins and the phototransduction cascade is regulated in other visual organs in Drosophila, such as the larval eye and adult ocelli. Using transcriptome analysis of larval PR-subtypes and ocellar PRs we identify and study new regulators required during PR differentiation or necessary for the expression of specific signaling molecules of the functional phototransduction pathway. We found that the transcription factor Krüppel (Kr) is enriched in the larval eye and controls PR differentiation by promoting Rh5 and Rh6 expression. We also identified Camta, Lola, Dve and Hazy as key genes acting during ocellar PR differentiation. Further we show that these transcriptional regulators control gene expression of the phototransduction cascade in both larval eye and adult ocelli. Our results show that PR cell type-specific transcriptome profiling is a powerful tool to identify key transcriptional regulators involved during several aspects of PR development and differentiation. Our findings greatly contribute to the understanding of how combinatorial action of key transcriptional regulators control PR development and the regulation of a functional phototransduction pathway in both larval eye and adult ocelli. PMID:26769100

  12. Adaptation to larval crowding in Drosophila ananassae and Drosophila nasuta nasuta: increased larval competitive ability without increased larval feeding rate.

    PubMed

    Nagarajan, Archana; Natarajan, Sharmila Bharathi; Jayaram, Mohan; Thammanna, Ananda; Chari, Sudarshan; Bose, Joy; Jois, Shreyas V; Joshi, Amitabh

    2016-06-01

    The standard view of adaptation to larval crowding in fruitflies, built on results from 25 years of multiple experimental evolution studies on Drosophila melanogaster, was that enhanced competitive ability evolves primarily through increased larval feeding and foraging rate, and increased larval tolerance to nitrogenous wastes, at the cost of efficiency of food conversion to biomass. These results were at odds from the predictions of classical K-selection theory, notably the expectation that selection at high density should result in the increase of efficiency of conversion of food to biomass, and were better interpreted through the lens of α-selection. We show here that populations of D. ananassae and D. n. nasuta subjected to extreme larval crowding evolve greater competitive ability and pre-adult survivorship at high density, primarily through a combination of reduced larval duration, faster attainment of minimum critical size for pupation, greater time efficiency of food conversion to biomass and increased pupation height, with a relatively small role of increased urea/ammonia tolerance, if at all. This is a very different suite of traits than that seen to evolve under similar selection in D. melanogaster, and seems to be closer to the expectations from the canonical theory of K-selection. We also discuss possible reasons for these differences in results across the three species. Overall, the results reinforce the view that our understanding of the evolution of competitive ability in fruitflies needs to be more nuanced than before, with an appreciation that there may be multiple evolutionary routes through which higher competitive ability can be attained. PMID:27350686

  13. Larval food quantity affects the capacity of adult mosquitoes to transmit human malaria.

    PubMed

    Shapiro, Lillian L M; Murdock, Courtney C; Jacobs, Gregory R; Thomas, Rachel J; Thomas, Matthew B

    2016-07-13

    Adult traits of holometabolous insects are shaped by conditions experienced during larval development, which might impact interactions between adult insect hosts and parasites. However, the ecology of larval insects that vector disease remains poorly understood. Here, we used Anopheles stephensi mosquitoes and the human malaria parasite Plasmodium falciparum, to investigate whether larval conditions affect the capacity of adult mosquitoes to transmit malaria. We reared larvae in two groups; one group received a standard laboratory rearing diet, whereas the other received a reduced diet. Emerging adult females were then provided an infectious blood meal. We assessed mosquito longevity, parasite development rate and prevalence of infectious mosquitoes over time. Reduced larval food led to increased adult mortality and caused a delay in parasite development and a slowing in the rate at which parasites invaded the mosquito salivary glands, extending the time it took for mosquitoes to become infectious. Together, these effects increased transmission potential of mosquitoes in the high food regime by 260-330%. Such effects have not, to our knowledge, been shown previously for human malaria and highlight the importance of improving knowledge of larval ecology to better understand vector-borne disease transmission dynamics. PMID:27412284

  14. Embryogenesis and Larval Biology of the Cold-Water Coral Lophelia pertusa

    PubMed Central

    Strömberg, Susanna M.; Dahl, Mikael P.; Lundälv, Tomas; Brooke, Sandra

    2014-01-01

    Cold-water coral reefs form spectacular and highly diverse ecosystems in the deep sea but little is known about reproduction, and virtually nothing about the larval biology in these corals. This study is based on data from two locations of the North East Atlantic and documents the first observations of embryogenesis and larval development in Lophelia pertusa, the most common framework-building cold-water scleractinian. Embryos developed in a more or less organized radial cleavage pattern from ∼160 µm large neutral or negatively buoyant eggs, to 120–270 µm long ciliated planulae. Embryogenesis was slow with cleavage occurring at intervals of 6–8 hours up to the 64-cell stage. Genetically characterized larvae were sexually derived, with maternal and paternal alleles present. Larvae were active swimmers (0.5 mm s−1) initially residing in the upper part of the water column, with bottom probing behavior starting 3–5 weeks after fertilization. Nematocysts had developed by day 30, coinciding with peak bottom-probing behavior, and possibly an indication that larvae are fully competent to settle at this time. Planulae survived for eight weeks under laboratory conditions, and preliminary results indicate that these planulae are planktotrophic. The late onset of competency and larval longevity suggests a high dispersal potential. Understanding larval biology and behavior is of paramount importance for biophysical modeling of larval dispersal, which forms the basis for predictions of connectivity among populations. PMID:25028936

  15. Patterning the dorsal longitudinal flight muscles (DLM) of Drosophila: insights from the ablation of larval scaffolds

    NASA Technical Reports Server (NTRS)

    Fernandes, J. J.; Keshishian, H.

    1996-01-01

    The six Dorsal Longitudinal flight Muscles (DLMs) of Drosophila develop from three larval muscles that persist into metamorphosis and serve as scaffolds for the formation of the adult fibers. We have examined the effect of muscle scaffold ablation on the development of DLMs during metamorphosis. Using markers that are specific to muscle and myoblasts we show that in response to the ablation, myoblasts which would normally fuse with the larval muscle, fuse with each other instead, to generate the adult fibers in the appropriate regions of the thorax. The development of these de novo DLMs is delayed and is reflected in the delayed expression of erect wing, a transcription factor thought to control differentiation events associated with myoblast fusion. The newly arising muscles express the appropriate adult-specific Actin isoform (88F), indicating that they have the correct muscle identity. However, there are frequent errors in the number of muscle fibers generated. Ablation of the larval scaffolds for the DLMs has revealed an underlying potential of the DLM myoblasts to initiate de novo myogenesis in a manner that resembles the mode of formation of the Dorso-Ventral Muscles, DVMs, which are the other group of indirect flight muscles. Therefore, it appears that the use of larval scaffolds is a superimposition on a commonly used mechanism of myogenesis in Drosophila. Our results show that the role of the persistent larval muscles in muscle patterning involves the partitioning of DLM myoblasts, and in doing so, they regulate formation of the correct number of DLM fibers.

  16. Larval food quantity affects the capacity of adult mosquitoes to transmit human malaria

    PubMed Central

    Shapiro, Lillian L. M.; Murdock, Courtney C.; Jacobs, Gregory R.; Thomas, Rachel J.; Thomas, Matthew B.

    2016-01-01

    Adult traits of holometabolous insects are shaped by conditions experienced during larval development, which might impact interactions between adult insect hosts and parasites. However, the ecology of larval insects that vector disease remains poorly understood. Here, we used Anopheles stephensi mosquitoes and the human malaria parasite Plasmodium falciparum, to investigate whether larval conditions affect the capacity of adult mosquitoes to transmit malaria. We reared larvae in two groups; one group received a standard laboratory rearing diet, whereas the other received a reduced diet. Emerging adult females were then provided an infectious blood meal. We assessed mosquito longevity, parasite development rate and prevalence of infectious mosquitoes over time. Reduced larval food led to increased adult mortality and caused a delay in parasite development and a slowing in the rate at which parasites invaded the mosquito salivary glands, extending the time it took for mosquitoes to become infectious. Together, these effects increased transmission potential of mosquitoes in the high food regime by 260–330%. Such effects have not, to our knowledge, been shown previously for human malaria and highlight the importance of improving knowledge of larval ecology to better understand vector-borne disease transmission dynamics. PMID:27412284

  17. Embryogenesis and larval biology of the cold-water coral Lophelia pertusa.

    PubMed

    Larsson, Ann I; Järnegren, Johanna; Strömberg, Susanna M; Dahl, Mikael P; Lundälv, Tomas; Brooke, Sandra

    2014-01-01

    Cold-water coral reefs form spectacular and highly diverse ecosystems in the deep sea but little is known about reproduction, and virtually nothing about the larval biology in these corals. This study is based on data from two locations of the North East Atlantic and documents the first observations of embryogenesis and larval development in Lophelia pertusa, the most common framework-building cold-water scleractinian. Embryos developed in a more or less organized radial cleavage pattern from ∼ 160 µm large neutral or negatively buoyant eggs, to 120-270 µm long ciliated planulae. Embryogenesis was slow with cleavage occurring at intervals of 6-8 hours up to the 64-cell stage. Genetically characterized larvae were sexually derived, with maternal and paternal alleles present. Larvae were active swimmers (0.5 mm s(-1)) initially residing in the upper part of the water column, with bottom probing behavior starting 3-5 weeks after fertilization. Nematocysts had developed by day 30, coinciding with peak bottom-probing behavior, and possibly an indication that larvae are fully competent to settle at this time. Planulae survived for eight weeks under laboratory conditions, and preliminary results indicate that these planulae are planktotrophic. The late onset of competency and larval longevity suggests a high dispersal potential. Understanding larval biology and behavior is of paramount importance for biophysical modeling of larval dispersal, which forms the basis for predictions of connectivity among populations. PMID:25028936

  18. Behavorial assessments of larval zebrafish neurotoxicology

    EPA Science Inventory

    Fishes have long been a popular organism in ecotoxicology research, and are increasingly used in human health research as an alternative animal model for chemical screening. Our laboratory incorporates a zebrafish (Danio rerio) embryo/larval assay to screen chemicals for developm...

  19. An extraordinarily long larval duration of 4.5 years from hatching to metamorphosis for teleplanic veligers of Fusitriton oregonensis.

    PubMed

    Strathmann, Megumi F; Strathmann, Richard R

    2007-10-01

    Veliger larvae of the NE Pacific snail Fusitriton oregonensis were reared in culture for 4.5 to 4.6 years from hatching to metamorphosis and through postlarval growth to reproduction. Larval shells grew in length from 0.20 to 3.9 mm. Late veligers grew slowly, but shell sizes increased even in the 4th and 5th years. Widths of larval shells at late stages equaled or exceeded those of the protoconchs of two juveniles from the field. Cultured larvae did not metamorphose until presented with subtidal rocks and associated biota. There was no indication of larval senescence: the first 2 years of postmetamorphic shell growth were slightly faster, and time from metamorphosis to first reproduction (3.3 years) was slightly less than for an individual that had developed to metamorphic competence in the plankton. A 4.5-year larval phase exceeds previous estimates for teleplanic larval durations and greatly exceeds estimates of the time for transport across oceans. This extraordinarily long larval period may exceed the usual duration in nature but shows that larval periods can be much longer than previously suspected without complete stasis in growth and with little if any loss of viability. PMID:17928522

  20. The impacts of larval density and protease inhibition on feeding in medicinal larvae of the greenbottle fly Lucilia sericata.

    PubMed

    Wilson, M R; Nigam, Y; Jung, W; Knight, J; Pritchard, D I

    2016-03-01

    Larval therapy, the therapeutic use of blowfly larvae to treat chronic wounds, is primarily used in debridement. There are, however, gaps in current knowledge of the optimal clinical application of the therapy and mechanisms of action in the debridement process. Using an artificial assay, two studies were undertaken to investigate these aspects of larval debridement by Lucilia sericata Meigen (Diptera: Calliphoridae); the first studied the effects of the density of larvae on tissue digestion and larval mass, and the second considered the effects on the same parameters of incorporating protease inhibitors into the feeding substrate. The total mass of tissue digested increased with larval density until saturation was observed at 5.0-7.5 larvae/cm(2) . This range was considered optimal as lower doses resulted in the removal of less tissue and higher doses offered no additional tissue removal and appeared to exacerbate competition for feeding. In the second study, increased protease inhibitor concentration led to significant decreases in tissue digestion and larval mass, suggesting that serine proteases, particularly trypsin, may play major roles in larval digestion. Such information is important in elucidating the main constituents that make up larval digestive products and may be significant in the development of new therapies. PMID:26463514

  1. MicroRNA-dependent roles of Drosha and Pasha in the Drosophila larval ovary morphogenesis.

    PubMed

    Yang, Huiming; Li, Mengjie; Hu, Xiaolong; Xin, Tianchi; Zhang, Shu; Zhao, Gengchun; Xuan, Tao; Li, Mingfa

    2016-08-15

    The Drosophila larval ovary morphogenesis mainly involves coordinated development of somatic and germ cell lineages that is essential for forming a correct number of niche-germline stem cell (GSC) units (ovarioles) in the adult ovary. Ecdysone, Insulin, Activin, Dpp and EGFR signaling pathways form a regulatory network that orchestrates ovarian soma and germ line throughout larval development. Identification and characterization of additional genes or machineries involved in this process will provide more insights into the underlying mechanisms. Here, we show that the core microRNA (miRNA) pathway components Drosha and Pasha are required for coordinated development of somatic and germ cell precursors in the larval ovary. Drosha or pasha mutants display defective proliferation of primordial germ cells (PGCs), the precursors of GSCs prior to late third larval instar (LL3) and promoted PGC differentiation at LL3. In the mean time, loss of Drosha or Pasha function perturbs somatic precursor development, causing defects in formation of terminal filaments (TFs), a major composition of the GSC niche at LL3, as well as in TF precursor accumulation at early larval stages. Comparative analysis of the mutant phenotypes reveals that three other key miRNA pathway components, Dicer-1 (Dcr-1), Loquacious (Loqs) and Argonaute-1 (Ago-1) have similar effects as Drosha and Pasha indicated above, suggesting a role of the canonical miRNA pathway in the ovary development. Furthermore, genome-wide screening and genetic studies identify a set of Drosha-controlled miRNAs including miR-8, miR-14, miR-33, miR-184, miR-317 and let-7-C that function in this gonadogenesis. Taken together, this study provides the first ever demonstration that miRNA-mediated regulation is involved in the Drosophila larval ovary morphogenesis. PMID:27339292

  2. Obligate larval inhibition of Ostertagia gruehneri in Rangifer tarandus? Causes and consequences in an Arctic system.

    PubMed

    Hoar, Bryanne M; Eberhardt, Alexander G; Kutz, Susan J

    2012-09-01

    Larval inhibition is a common strategy of Trichostrongylidae nematodes that may increase survival of larvae during unfavourable periods and concentrate egg production when conditions are favourable for development and transmission. We investigated the propensity for larval inhibition in a population of Ostertagia gruehneri, the most common gastrointestinal Trichostrongylidae nematode of Rangifer tarandus. Initial experimental infections of 4 reindeer with O. gruehneri sourced from the Bathurst caribou herd in Arctic Canada suggested that the propensity for larval inhibition was 100%. In the summer of 2009 we infected 12 additional reindeer with the F1 and F2 generations of O. gruehneri sourced from the previously infected reindeer to further investigate the propensity of larval inhibition. The reindeer were divided into 2 groups and half were infected before the summer solstice (17 June) and half were infected after the solstice (16 July). Reindeer did not shed eggs until March 2010, i.e. 8 and 9 months post-infection. These results suggest obligate larval inhibition for at least 1 population of O. gruehneri, a phenomenon that has not been conclusively shown for any other trichostrongylid species. Obligate inhibition is likely to be an adaptation to both the Arctic environment and to a migratory host and may influence the ability of O. gruehneri to adapt to climate change. PMID:22953998

  3. EXPOSURE METHOD CONSIDERATIONS FOR MEASURING VITELLOGENIN EXPRESSION IN LARVAL AND MALE FATHEAD MINNOWS (PIMEPHALES PROMELAS)

    EPA Science Inventory

    Our laboratory has developed methods for measuring the expression of the vitellogenin (Vg) gene in larval and adult male fathead minnows. During this development we found several conditions that affect background Vg levels and we observed preconditions for the expression of this...

  4. A developmental and energetic basis linking larval oyster shell formation to acidification sensitivity

    NASA Astrophysics Data System (ADS)

    Waldbusser, George G.; Brunner, Elizabeth L.; Haley, Brian A.; Hales, Burke; Langdon, Christopher J.; Prahl, Frederick G.

    2013-05-01

    Acidified waters are impacting commercial oyster production in the U.S. Pacific Northwest, and favorable carbonate chemistry conditions are predicted to become less frequent. Within 48 h of fertilization, unshelled Pacific oyster (Crassostrea gigas) larvae precipitate roughly 90% of their body weight as calcium carbonate. We measured stable carbon isotopes in larval shell and tissue and in algal food and seawater dissolved inorganic carbon in a longitudinal study of larval development and growth. Using these data and measured biochemical composition of larvae, we show that sensitivity of initial shell formation to ocean acidification results from diminished ability to isolate calcifying fluid from surrounding seawater, a limited energy budget and a strong kinetic demand for calcium carbonate precipitation. Our results highlight an important link between organism physiology and mineral kinetics in larval bivalves and suggest the consideration of mineral kinetics may improve understanding winners and losers in a high CO2 world.

  5. ‘Peer pressure’ in larval Drosophila?

    PubMed Central

    Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

    2014-01-01

    ABSTRACT Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on ‘peer pressure’, that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. PMID:24907371

  6. Detecting critical periods in larval flatfish populations

    NASA Astrophysics Data System (ADS)

    Chambers, R. Christopher; Witting, David A.; Lewis, Stephen J.

    2001-06-01

    We evaluate the time-course of deaths and evidence of periods of increased mortality (i.e., critical periods) in laboratory populations of larval flatfish. First, we make the distinction between age-at-death and abundance-at-time data for fish larvae, the latter being typical in studies of natural populations. Next, we describe an experimental investigation of age- and temperature-dependent mortality in larval winter flounder, Pseudopleuronectes americanus. The survivorship curves of these populations differed significantly in both the magnitude and time-course of mortality among the four water temperatures evaluated (7, 10, 13, and 16°C). Mortality was highest in the cooler temperatures and concentrated in the third quarter of larval life, largely concurrent with settlement of surviving members of the cohort. Among the statistical methods for analysing survival data, the proportional-hazards model with time-varying covariates proved best at capturing the patterns of age-specific mortalities. We conclude that fair appraisals of recruitment hypotheses which are predicated on periods of high, age-specific mortality that vary with environmental conditions (e.g., Hjort's critical period hypothesis) will require: (1) data that are based on age, not time; (2) data that are of higher temporal resolution than commonly available at present and (3) analytical methods that are sensitive to irregularities in survivorship curves. We suggest four research approaches for evaluating critical periods in nature.

  7. Para Candidatos en Programas de Centros de Cuidado y Educacion Infantil con Bebes y "Toddlers": Asociado en Desarrollo Infantil Sistema de Evaluacion y Normas de Competencia CDA (Infant/Toddler Caregivers in Center-Based Programs: The Child Development Associate Assessment System and Competency Standards).

    ERIC Educational Resources Information Center

    Council for Early Childhood Professional Recognition, Washington, DC.

    This Spanish-language booklet outlines the requirements of the Child Development Associate (CDA) credential for caregivers working in center-based infant and toddler day care programs. Part 1 provides an overview of the CDA credentialing system and the various options, settings, standards, and stages of the CDA assessment system. Part 2 explains…

  8. Para Candidatos en Programas de Centros de Cuidado y Educacion Infantil con Ninos de Edad Pre-escolar: Asociado en Desarrollo Infantil Sistema de Evaluacion y Normas de Competencia CDA (Preschool Caregivers in Center-Based Programs: The Child Development Associate Assessment System and Competency Standards).

    ERIC Educational Resources Information Center

    Council for Early Childhood Professional Recognition, Washington, DC.

    This Spanish-language booklet outlines the requirements of the Child Development Associate (CDA) credential for preschool teachers or caregivers who work in center-based preschool day care programs. Part 1 provides an overview of the CDA credentialing system and the various options, settings, standards, and stages of the CDA assessment system.…

  9. An electric beam trawl for the capture of larval lampreys

    USGS Publications Warehouse

    McLain, Alberton; Dahl, Frederick H.

    1968-01-01

    The chemicals used to control the sea lamprey, Petromyzon marinus, in the Great Lakes have drastically reduced populations of larval lampreys in tributary streams. These larvicides are too costly and difficult to apply, however, in inland lakes, estuaries, and bays. Populations of sea lampreys in these areas constitute a threat to the refinement of the control. The gear available to locate, ample, and evaluate larval populations in deep water are inefficient. Electric shockers, satisfactory for collecting ammocoetes in streams, are limited to shallow water. The use of mechanical devices such as the Petersen dredge, anchor dredge, and the orange-peel dredge is time consuming, inefficient, and relatively ineffective in providing reliable quantitative evaluation of population size and composition over large areas of bottom. A device was required to sample adequately many areas in a short period of time, regardless of the depth of water. Mobility also was essential to permit operation of the unit in the various Great Lakes and in inland waters. An electrified beam trawl has been developed that most nearly meets these requirements. It has been used successfully to collect larvae of the sea lamprey, American brook lamprey (Lampetra lamottei), northern brook lamprey (Ichthyomyzon fossor), and silver lamprey (I. unicuspis). Effectiveness of the trawl did not appear to differ with species.

  10. FACS purification of Drosophila larval Neuroblasts for next generation sequencing

    PubMed Central

    Conder, Ryan; Schmauss, Gerald; Knoblich, Juergen A.

    2014-01-01

    Elegant tools are available for the genetic analysis of neural stem cell lineages in Drosophila, but a methodology for purifying stem cells and their differentiated progeny for transcriptome analysis is currently missing. Previous attempts to overcome this problem either involved using RNA isolated from whole larval brain tissue or co-transcriptional in vivo mRNA tagging. As both methods have limited cell type specificity, we developed a protocol for the isolation of Drosophila neural stem cells (neuroblasts, NBs) and their differentiated sibling cells by FACS. We dissected larval brains from fly strains expressing GFP under the control of a NB lineage-specific GAL4 line. Upon dissociation, we made use of differences in GFP intensity and cell size to separate NBs and neurons. The resulting cell populations are over 98% pure and can readily be used for live imaging or gene expression analysis. Our method is optimized for neural stem cells, but it can also be applied to other Drosophila cell types. Primary cell suspensions and sorted cell populations can be obtained within 1 d; material for deep-sequencing library preparation can be obtained within 4 d. PMID:23660757

  11. Complex larval connectivity patterns among marine invertebrate populations

    PubMed Central

    Becker, Bonnie J.; Levin, Lisa A.; Fodrie, F. Joel; McMillan, Pat A.

    2007-01-01

    Based on the belief that marine larvae, which can spend days to months in the planktonic stage, could be transported considerable distances by ocean currents, it has long been assumed that populations of coastal species with a planktonic larval stage are demographically open and highly “connected.” Such assumptions about the connectivity of coastal populations govern approaches to managing marine resources and shape our fundamental understanding of population dynamics and evolution, yet are rarely tested directly due to the small size and high mortality of marine larvae in a physically complex environment. Here, we document a successful application of elemental fingerprinting as a tracking tool to determine sources of settled invertebrates and show that coastal mussel larvae, previously thought to be highly dispersed, can be retained within 20–30 km of their natal origin. We compare two closely related and co-occurring species, Mytilus californianus and Mytilus galloprovincialis, and determine that, despite expected similarities, they exhibit substantially different connectivity patterns. Our use of an in situ larval culturing technique overcomes the previous challenge of applying microchemical tracking methods to species with completely planktonic development. The exchange of larvae and resulting connectivities among marine populations have fundamental consequences for the evolution and ecology of species and for the management of coastal resources. PMID:17360636

  12. System for maintaining sediment suspensions during larval fish studies

    USGS Publications Warehouse

    Chilton, E.W., II

    1991-01-01

    A new system was developed for maintaining suspensions of inorganic solids during laboratory studies on early life stages of fish. Microfine bentonite was successfully held in suspension in specially constructed units during a 21-d fishless test, a 28-d experiment with juvenile green sunfish (lepomis cyanellus), and four shorter experiments (5-9 d) with four species of larval fishes, white sucker (catostomus commersoni), northern pike (esox lucius), channel catfish (ictalurus punctatus), and walleye (stizostedion vitreum). Each experiment on larval fish was conducted until the yolk-sac had been absorbed. Concentrations of bentonite ranged from 0 to 728 mg/l. Each unit consisted of a holding chamber set in a stainless steel bowl and two submersible pumps that recirculated the suspension. Turbidity readings remained nearly constant throughout each experiment. Because the turbidity of suspensions was well correlated with bentonite concentration (r2 = 0.989) And easy to measure, turbidity was used as an indicator of concentration. The system is inexpensive, easy to assemble, and does not require a diluter system to maintain constant concentrations of suspended material.

  13. Larval Connectivity and the International Management of Fisheries

    PubMed Central

    Kough, Andrew S.; Paris, Claire B.; Butler, Mark J.

    2013-01-01

    Predicting the oceanic dispersal of planktonic larvae that connect scattered marine animal populations is difficult, yet crucial for management of species whose movements transcend international boundaries. Using multi-scale biophysical modeling techniques coupled with empirical estimates of larval behavior and gamete production, we predict and empirically verify spatio-temporal patterns of larval supply and describe the Caribbean-wide pattern of larval connectivity for the Caribbean spiny lobster (Panulirus argus), an iconic coral reef species whose commercial value approaches $1 billion USD annually. Our results provide long sought information needed for international cooperation in the management of marine resources by identifying lobster larval connectivity and dispersal pathways throughout the Caribbean. Moreover, we outline how large-scale fishery management could explicitly recognize metapopulation structure by considering larval transport dynamics and pelagic larval sanctuaries. PMID:23762273

  14. Larval connectivity and the international management of fisheries.

    PubMed

    Kough, Andrew S; Paris, Claire B; Butler, Mark J

    2013-01-01

    Predicting the oceanic dispersal of planktonic larvae that connect scattered marine animal populations is difficult, yet crucial for management of species whose movements transcend international boundaries. Using multi-scale biophysical modeling techniques coupled with empirical estimates of larval behavior and gamete production, we predict and empirically verify spatio-temporal patterns of larval supply and describe the Caribbean-wide pattern of larval connectivity for the Caribbean spiny lobster (Panulirus argus), an iconic coral reef species whose commercial value approaches $1 billion USD annually. Our results provide long sought information needed for international cooperation in the management of marine resources by identifying lobster larval connectivity and dispersal pathways throughout the Caribbean. Moreover, we outline how large-scale fishery management could explicitly recognize metapopulation structure by considering larval transport dynamics and pelagic larval sanctuaries. PMID:23762273

  15. Larval Starvation to Satiation: Influence of Nutrient Regime on the Success of Acanthaster planci

    PubMed Central

    Wolfe, Kennedy; Graba-Landry, Alexia; Dworjanyn, Symon A.; Byrne, Maria

    2015-01-01

    High density populations of the crown-of-thorns seastar, Acanthaster planci, are a major contributor to the decline of coral reefs, however the causes behind periodic outbreaks of this species are not understood. The enhanced nutrients hypothesis posits that pulses of enhanced larval food in eutrophic waters facilitate metamorphic success with a flow-on effect for population growth. The larval resilience hypothesis suggests that A. planci larvae naturally thrive in tropical oligotrophic waters. Both hypotheses remain to be tested empirically. We raised A. planci larvae in a range of food regimes from starvation (no food) to satiation (excess food). Algal cell concentration and chlorophyll levels were used to reflect phytoplankton conditions in nature for oligotrophic waters (0-100 cells ml-1; 0-0.01 μg chl a L-1), natural background levels of nutrients on the Great Barrier Reef (GBR) (1,000-10,000 cells ml-1; 0.1-1.0 μg chl a L-1), and enhanced eutrophic conditions following runoff events (100,000 cells ml-1; 10 μg chl a L-1). We determine how these food levels affected larval growth and survival, and the metamorphic link between larval experience and juvenile quality (size) in experiments where food ration per larvae was carefully controlled. Phytoplankton levels of 1 μg chl a L-1, close to background levels for some reefs on the GBR and following flood events, were optimal for larval success. Development was less successful above and below this food treatment. Enhanced larval performance at 1 μg chl a L-1 provides empirical support for the enhanced nutrients hypothesis, but up to a limit, and emphasizes the need for appropriate mitigation strategies to reduce eutrophication and the consequent risk of A. planci outbreaks. PMID:25790074

  16. Divergence of larval resource acquisition for water conservation and starvation resistance in Drosophila melanogaster.

    PubMed

    Parkash, Ravi; Aggarwal, Dau Dayal; Ranga, Poonam; Singh, Divya

    2012-07-01

    Laboratory selection experiments have evidenced storage of energy metabolites in adult flies of desiccation and starvation resistant strains of D. melanogaster but resource acquisition during larval stages has received lesser attention. For wild populations of D. melanogaster, it is not clear whether larvae acquire similar or different energy metabolites for desiccation and starvation resistance. We tested the hypothesis whether larval acquisition of energy metabolites is consistent with divergence of desiccation and starvation resistance in darker and lighter isofemale lines of D. melanogaster. Our results are interesting in several respects. First, we found contrasting patterns of larval resource acquisition, i.e., accumulation of higher carbohydrates during 3rd instar larval stage of darker flies versus higher levels of triglycerides in 1st and 2nd larval instars of lighter flies. Second, 3rd instar larvae of darker flies showed ~40 h longer duration of development at 21°C; and greater accumulation of carbohydrates (trehalose and glycogen) in fed larvae as compared with larvae non-fed after 150 h of egg laying. Third, darker isofemale lines have shown significant increase in total water content (18%); hemolymph (86%) and dehydration tolerance (11%) as compared to lighter isofemale lines. Loss of hemolymph water under desiccation stress until death was significantly higher in darker as compared to lighter isofemale lines but tissue water loss was similar. Fourth, for larvae of darker flies, about 65% energy content is contributed by carbohydrates for conferring greater desiccation resistance while the larvae of lighter flies acquire 2/3 energy from lipids for sustaining starvation resistance; and such energy differences persist in the newly eclosed flies. Thus, larval stages of wild-caught darker and lighter flies have evolved independent physiological processes for the accumulation of energy metabolites to cope with desiccation or starvation stress. PMID

  17. Effects of metal and predator stressors in larval southern toads (Anaxyrus terrestris).

    PubMed

    Rumrill, Caitlin T; Scott, David E; Lance, Stacey L

    2016-08-01

    Natural and anthropogenic stressors typically do not occur in isolation; therefore, understanding ecological risk of contaminant exposure should account for potential interactions of multiple stressors. Realistically, common contaminants can also occur chronically in the environment. Because parental exposure to stressors may cause transgenerational effects on offspring, affecting their ability to cope with the same or novel environmental stressors, the exposure histories of generations preceding that being tested should be considered. To examine multiple stressor and parental exposure effects we employed a 2 × 2 × 2 factorial design in outdoor 1000-L mesocosms (n = 24). Larval southern toads (Anaxyrus terrestris), bred from parents collected from reference and metal-contaminated sites, were exposed to two levels of both an anthropogenic (copper-0, 30 µg/L Cu) and natural (predator cue - present/absent) stressor and reared to metamorphosis. Toads from the metal-contaminated parental source population were smaller at metamorphosis and had delayed development; i.e., a prolonged larval period. Similarly, larval Cu exposure also reduced size at metamorphosis and prolonged the larval period. We, additionally, observed a significant interaction between larval Cu and predator-cue exposure on larval period, wherein delayed emergence was only present in the 30-µg/L Cu treatments in the absence of predator cues. The presence of parental effects as well as an interaction between aquatic stressors on commonly measured endpoints highlight the importance of conducting multistressor studies across generations to obtain data that are more relevant to field conditions in order to determine population-level effects of contaminant exposure. PMID:27272662

  18. The safety of 17a-methyltestosterone administered in feed to larval Nile tilapia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Techniques developed to control sexual differentiation in fishes have typically involved androgen or estrogen (i.e., steroid) treatment, which directs sexual differentiation toward males or females. Treatment regimens have included immersion of larval fish in water containing a steroid, incorporati...

  19. Functional Assays and Alternative Species: Using Larval Zebrafish in Developmental Neurotoxicity Screening

    EPA Science Inventory

    The U.S. Environmental Protection Agency is developing and evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. Towards this goal, we are exploring methods to detect developmental neurotoxicants in very young larval zebrafish. We have...

  20. Larval quality of aquacultured Florida pompano, Trachinotus carolinus L. fed rotifers enriched with selected commercial diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of larviculture methods for marine finfish has been a major bottleneck to ensure a consistent and reliable source of seed stock. This study examined the effect of selected rotifer enrichment diets on growth, survival, and fatty acid content of larval Florida pompano, Trachinotus carolin...

  1. Larval performance of aquacultured Florida pompano, Trachinotus carolinus L. fed rotifers enriched with selected commercial diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of larviculture methods for marine finfish has been a major bottleneck to ensure a consistent and reliable source of seed stock. This study examined the effect of selected rotifer enrichment diets on growth, survival, and fatty acid content of larval Florida pompano, Trachinotus carolin...

  2. Larval habitat of Anopheles philippinensis: a vector of malaria in Bangladesh.

    PubMed Central

    Elias, M.

    1996-01-01

    This article reviews the various types of larval habitat of the malaria vector Anopheles philippinensis Ludlow in Bangladesh and characterizes its breeding ecology. Discussed also are the possible implications of the environmental changes on its breeding habitats resulting from intensified land use brought about by population increase and developments in irrigation and water resources. PMID:8823969

  3. Evaluating sampling strategies for larval cisco (Coregonus artedi)

    USGS Publications Warehouse

    Myers, J.T.; Stockwell, J.D.; Yule, D.L.; Black, J.A.

    2008-01-01

    To improve our ability to assess larval cisco (Coregonus artedi) populations in Lake Superior, we conducted a study to compare several sampling strategies. First, we compared density estimates of larval cisco concurrently captured in surface waters with a 2 x 1-m paired neuston net and a 0.5-m (diameter) conical net. Density estimates obtained from the two gear types were not significantly different, suggesting that the conical net is a reasonable alternative to the more cumbersome and costly neuston net. Next, we assessed the effect of tow pattern (sinusoidal versus straight tows) to examine if propeller wash affected larval density. We found no effect of propeller wash on the catchability of larval cisco. Given the availability of global positioning systems, we recommend sampling larval cisco using straight tows to simplify protocols and facilitate straightforward measurements of volume filtered. Finally, we investigated potential trends in larval cisco density estimates by sampling four time periods during the light period of a day at individual sites. Our results indicate no significant trends in larval density estimates during the day. We conclude estimates of larval cisco density across space are not confounded by time at a daily timescale. Well-designed, cost effective surveys of larval cisco abundance will help to further our understanding of this important Great Lakes forage species.

  4. Maternal diet and larval diet influence survival skills of larval red drum Sciaenops ocellatus.

    PubMed

    Perez, K O; Fuiman, L A

    2015-04-01

    Larval red drum Sciaenops ocellatus survival, turning rate, routine swimming speed, escape response latency and escape response distance were significantly correlated with essential fatty-acid (EFA) concentrations in eggs. Of the five traits that varied with egg EFA content, two (escape response latency and routine swimming speed) were significantly different when larvae were fed enriched diets compared with the low fatty-acid diet, indicating that the larval diet can compensate for some imbalances in egg composition. Turning rate during routine swimming and escape response distance, however, did not change when larvae predicted to have low performance (based on egg composition) were fed an enriched diet, indicating that these effects of egg composition may be irreversible. Escape response distances and survival rates of larvae predicted to perform well (based on egg composition) and fed highly enriched diets were lower than expected, suggesting that high levels of EFA intake can be detrimental. Altogether, these results suggest that both maternal diet, which is responsible for egg EFA composition, and larval diet may play a role in larval survivorship and recruitment. PMID:25740661

  5. Acidification reduced growth rate but not swimming speed of larval sea urchins

    PubMed Central

    Chan, Kit Yu Karen; García, Eliseba; Dupont, Sam

    2015-01-01

    Swimming behaviors of planktonic larvae impact dispersal and population dynamics of many benthic marine invertebrates. This key ecological function is modulated by larval development dynamics, biomechanics of the resulting morphology, and behavioral choices. Studies on ocean acidification effects on larval stages have yet to address this important interaction between development and swimming under environmentally-relevant flow conditions. Our video motion analysis revealed that pH covering present and future natural variability (pH 8.0, 7.6 and 7.2) did not affect age-specific swimming of larval green urchin Strongylocentrotus droebachiensis in still water nor in shear, despite acidified individuals being significantly smaller in size (reduced growth rate). This maintenance of speed and stability in shear was accompanied by an overall change in size-corrected shape, implying changes in swimming biomechanics. Our observations highlight strong evolutionary pressure to maintain swimming in a varying environment and the plasticity in larval responses to environmental change. PMID:25978405

  6. NON-INVASIVE NEUROTOXICITY ASSAY USING LARVAL MEDAKA

    EPA Science Inventory

    We present a method for non-invasive electrophysiological analysis of rapid escape responses in intact, freely behaving larval medaka (Oryzias latipes) before and after short-term exposure to environmental toxicants. ecordings are obtained as a larval medaka swims in a small cham...

  7. EFFECTS OF DIET ON GROWTH AND SURVIVAL OF LARVAL WALLYES

    EPA Science Inventory

    The effects of diet quality on larval walleye (Stizostedion vitreum vitreum) growth and survival are described. The cyclopoid copepod Diacyclops thomasi consumed larval walleyes within 10 min at dense copepod concentrations and within 1 day at lower densities (500 organisms/L). A...

  8. Larval fish distribution in the St. Louis River estuary

    EPA Science Inventory

    Our objective was to determine what study design, environmental, and habitat variables contribute to the distribution and abundance of larval fish in the St. Louis River estuary. Larval fish habitat associations are poorly understood in Great Lakes coastal wetlands, yet critical ...

  9. Larval dispersal drives trophic structure across Pacific coral reefs.

    PubMed

    Stier, Adrian C; Hein, Andrew M; Parravicini, Valeriano; Kulbicki, Michel

    2014-01-01

    Top predators are a critical part of healthy ecosystems. Yet, these species are often absent from spatially isolated habitats leading to the pervasive view that fragmented ecological communities collapse from the top down. Here we study reef fish from coral reef communities across the Pacific Ocean. Our analysis shows that species richness of reef fish top predators is relatively stable across habitats that vary widely in spatial isolation and total species richness. In contrast, species richness of prey reef fish declines rapidly with increasing isolation. By consequence, species-poor communities from isolated islands have three times as many predator species per prey species as near-shore communities. We develop and test a colonization-extinction model to reveal how larval dispersal patterns shape this ocean-scale gradient in trophic structure. PMID:25412873

  10. Environmentally relevant concentrations of microplastic particles influence larval fish ecology.

    PubMed

    Lönnstedt, Oona M; Eklöv, Peter

    2016-06-01

    The widespread occurrence and accumulation of plastic waste in the environment have become a growing global concern over the past decade. Although some marine organisms have been shown to ingest plastic, few studies have investigated the ecological effects of plastic waste on animals. Here we show that exposure to environmentally relevant concentrations of microplastic polystyrene particles (90 micrometers) inhibits hatching, decreases growth rates, and alters feeding preferences and innate behaviors of European perch (Perca fluviatilis) larvae. Furthermore, individuals exposed to microplastics do not respond to olfactory threat cues, which greatly increases predator-induced mortality rates. Our results demonstrate that microplastic particles operate both chemically and physically on larval fish performance and development. PMID:27257256

  11. Similarities and Differences for Swimming in Larval and Adult Lampreys.

    PubMed

    McClellan, Andrew D; Pale, Timothée; Messina, J Alex; Buso, Scott; Shebib, Ahmad

    2016-01-01

    The spinal locomotor networks controlling swimming behavior in larval and adult lampreys may have some important differences. As an initial step in comparing the locomotor systems in lampreys, in larval animals the relative timing of locomotor movements and muscle burst activity were determined and compared to those previously published for adults. In addition, the kinematics for free swimming in larval and adult lampreys was compared in detail for the first time. First, for swimming in larval animals, the neuromechanical phase lag between the onsets or terminations of muscle burst activity and maximum concave curvature of the body increased with increasing distance along the body, similar to that previously shown in adults. Second, in larval lampreys, but not adults, absolute swimming speed (U; mm s(-1)) increased with animal length (L). In contrast, normalized swimming speed (U'; body lengths [bl] s(-1)) did not increase with L in larval or adult animals. In both larval and adult lampreys, U' and normalized wave speed (V') increased with increasing tail-beat frequency. Wavelength and mechanical phase lag did not vary significantly with tail-beat frequency but were significantly different in larval and adult animals. Swimming in larval animals was characterized by a smaller U/V ratio, Froude efficiency, and Strouhal number than in adults, suggesting less efficient swimming for larval animals. In addition, during swimming in larval lampreys, normalized lateral head movements were larger and normalized lateral tail movements were smaller than for adults. Finally, larval animals had proportionally smaller lateral surface areas of the caudal body and fin areas than adults. These differences are well suited for larval sea lampreys that spend most of the time buried in mud/sand, in which swimming efficiency is not critical, compared to adults that would experience significant selection pressure to evolve higher-efficiency swimming to catch up to and attach to fish for

  12. Swimming Speed of Larval Snail Does Not Correlate with Size and Ciliary Beat Frequency

    PubMed Central

    Chan, Kit Yu Karen; Jiang, Houshuo; Padilla, Dianna K.

    2013-01-01

    Many marine invertebrates have planktonic larvae with cilia used for both propulsion and capturing of food particles. Hence, changes in ciliary activity have implications for larval nutrition and ability to navigate the water column, which in turn affect survival and dispersal. Using high-speed high-resolution microvideography, we examined the relationship between swimming speed, velar arrangements, and ciliary beat frequency of freely swimming veliger larvae of the gastropod Crepidula fornicata over the course of larval development. Average swimming speed was greatest 6 days post hatching, suggesting a reduction in swimming speed towards settlement. At a given age, veliger larvae have highly variable speeds (0.8–4 body lengths s−1) that are independent of shell size. Contrary to the hypothesis that an increase in ciliary beat frequency increases work done, and therefore speed, there was no significant correlation between swimming speed and ciliary beat frequency. Instead, there are significant correlations between swimming speed and visible area of the velar lobe, and distance between centroids of velum and larval shell. These observations suggest an alternative hypothesis that, instead of modifying ciliary beat frequency, larval C. fornicata modify swimming through adjustment of velum extension or orientation. The ability to adjust velum position could influence particle capture efficiency and fluid disturbance and help promote survival in the plankton. PMID:24367554

  13. A review of postfeeding larval dispersal in blowflies: implications for forensic entomology

    NASA Astrophysics Data System (ADS)

    Gomes, Leonardo; Godoy, Wesley Augusto Conde; von Zuben, Claudio José

    2006-05-01

    Immature and adult stages of blowflies are one of the primary invertebrate consumers of decomposing animal organic matter. When the food supply is consumed or when the larvae complete their development and migrate prior to the total removal of the larval substrate, they disperse to find adequate places for pupation, a process known as postfeeding larval dispersal. Several important ecological and physiological aspects of this process were studied since the work by Green (Ann Appl Biol 38:475, 1951) 50 years ago. An understanding of postfeeding larval dispersal can be useful for determining the postmortem interval (PMI) of human cadavers in legal medicine, particularly because this interval may be underestimated if older dispersing larvae or those that disperse longer, faster, and deeper are not taken into account. In this article, we review the process of postfeeding larval dispersal and its implications for legal medicine, in particular showing that aspects such as burial behavior and competition among species of blowflies can influence this process and consequently, the estimation of PMI.

  14. Ingestibility, digestibility, and engineered biological control potential of Flavobacterium hibernum, isolated from larval mosquito habitats.

    PubMed

    Chen, Shicheng; Kaufman, Michael G; Korir, Michelle L; Walker, Edward D

    2014-02-01

    Flavobacterium hibernum, isolated from larval habitats of the eastern tree hole mosquito, A. triseriatus, remained suspended in the larval feeding zone much longer (8 days) than other bacteria. Autofluorescent protein markers were developed for the labeling of F. hibernum with a strong flavobacterial expression system. Green fluorescent protein (GFP)-tagged F. hibernum cells were quickly consumed by larval mosquitoes at an ingestion rate of 9.5 × 10(4)/larva/h. The ingested F. hibernum cells were observed mostly in the foregut and midgut and rarely in the hindgut, suggesting that cells were digested and did not pass the gut viably. The NanoLuc luciferase reporter system was validated for quantitative larval ingestion rate and bacterial fate analyses. Larvae digested 1.87 × 10(5) cells/larva/h, and few F. hibernum cells were excreted intact. Expression of the GFP::Cry11A fusion protein with the P20 chaperone protein from Bacillus thuringiensis H-14 was successfully achieved in F. hibernum. Whole-cell bioassays of recombinant F. hibernum exhibited high larvicidal activity against A. triseriatus in microplates and in microcosms simulating tree holes. F. hibernum cells persisted in microcosms at 100, 59, 30, and 10% of the initial densities at days 1, 2, 3, and 6, respectively, when larvae were absent, while larvae consumed nearly all of the F. hibernum cells within 3 days of their addition to microcosms. PMID:24296502

  15. Larval cases of caddisfly (Insecta: Trichoptera) affinity in Early Permian marine environments of Gondwana.

    PubMed

    Mouro, Lucas D; Zatoń, Michał; Fernandes, Antonio C S; Waichel, Breno L

    2016-01-01

    Caddisflies (Trichoptera) are small, cosmopolitan insects closely related to the Lepidoptera (moths and butterflies). Most caddisflies construct protective cases during their larval development. Although the earliest recognisable caddisflies date back to the early Mesozoic (Early and Middle Triassic), being particularly numerous and diverse during the Late Jurassic and Early Cretaceous, the first records of their larval case constructions are known exclusively from much younger, Early to Middle Jurassic non-marine deposits in the northern hemisphere. Here we present fossils from the Early Permian (Asselian-Sakmarian) marine deposits of Brazil which have strong morphological and compositional similarity to larval cases of caddisflies. If they are, which is very probable, these finds not only push back the fossil record of true caddisflies, but also indicate that their larvae constructed cases at the very beginning of their evolution in marine environments. Since modern caddisflies that construct larval cases in marine environments are only known from eastern Australia and New Zealand, we suggest that this marine ecology may have first evolved in western Gondwana during the Early Permian and later spread across southern Pangea. PMID:26765261

  16. Larval cases of caddisfly (Insecta: Trichoptera) affinity in Early Permian marine environments of Gondwana

    PubMed Central

    Mouro, Lucas D.; Zatoń, Michał; Fernandes, Antonio C.S.; Waichel, Breno L.

    2016-01-01

    Caddisflies (Trichoptera) are small, cosmopolitan insects closely related to the Lepidoptera (moths and butterflies). Most caddisflies construct protective cases during their larval development. Although the earliest recognisable caddisflies date back to the early Mesozoic (Early and Middle Triassic), being particularly numerous and diverse during the Late Jurassic and Early Cretaceous, the first records of their larval case constructions are known exclusively from much younger, Early to Middle Jurassic non-marine deposits in the northern hemisphere. Here we present fossils from the Early Permian (Asselian–Sakmarian) marine deposits of Brazil which have strong morphological and compositional similarity to larval cases of caddisflies. If they are, which is very probable, these finds not only push back the fossil record of true caddisflies, but also indicate that their larvae constructed cases at the very beginning of their evolution in marine environments. Since modern caddisflies that construct larval cases in marine environments are only known from eastern Australia and New Zealand, we suggest that this marine ecology may have first evolved in western Gondwana during the Early Permian and later spread across southern Pangea. PMID:26765261

  17. Energy beyond the pupal stage: larval nutrition and its long-time consequences for male mating performance in a scorpionfly.

    PubMed

    Engels, Sierk; Sauer, Klaus Peter

    2007-07-01

    The basic requirement for selection to take effect is variation in fitness relevant traits among individuals of a population. This study is concerned with the question whether environmental conditions met during an early phase of life history that is dominated by the natural component of selection will affect traits and behaviour in a sexual selection context after metamorphosis in a holometabolous insect species. We examined the effects of nutrition as a proximate factor responsible for intrasexual phenotypic variation in the mating performance of male Panorpa vulgaris (Mecoptera: Panorpidae). For this purpose, we manipulated food availability during larval development as well as during adulthood. To obtain matings and to increase their reproductive success males must secrete salivary masses which are then consumed by the females during copulation. The results of the present study are consistent with those of previous studies demonstrating a strong effect of nutrition during adulthood on various fitness relevant traits (salivary gland development, saliva investment in copulations, etc.). But moreover, we could show that food availability during larval development affected male body weight and that there was an interaction between larval and adult diet affecting salivary gland weight relative to body weight. Therefore, food availability during the larval stage can become an important and limiting factor for salivary gland development (and mating success) depending on food availability during adulthood. Several other variables (number of salivary masses, copulation duration, salivary mass weight and saliva investment) seemed not to be associated with larval nutrition. PMID:17572436

  18. Rapid declines in metabolism explain extended coral larval longevity

    NASA Astrophysics Data System (ADS)

    Graham, E. M.; Baird, A. H.; Connolly, S. R.; Sewell, M. A.; Willis, B. L.

    2013-06-01

    Lecithotrophic, or non-feeding, marine invertebrate larvae generally have shorter pelagic larval durations (PLDs) than planktotrophic larvae. However, non-feeding larvae of scleractinian corals have PLDs far exceeding those of feeding larvae of other organisms and predictions of PLD based on energy reserves and metabolic rates, raising questions about how such longevity is achieved. Here, we measured temporal changes in metabolic rates and total lipid content of non-feeding larvae of four species of reef corals to determine whether changes in energy utilization through time contribute to extended larval durations. The temporal dynamics of both metabolic rates and lipid content were highly consistent among species. Prior to fertilization, metabolic rates were low (2.73-8.63 nmol O2 larva-1 h-1) before rapidly increasing to a peak during embryogenesis and early development 1-2 days after spawning. Metabolic rates remained high until shortly after larvae first became competent to metamorphose and then declined by up to two orders of magnitude to levels at or below rates seen in unfertilized eggs over the following week. Larvae remained in this state of low metabolic activity for up to 2 months. Consistent with temporal patterns in metabolic rates, depletion of lipids was extremely rapid during early development and then slowed dramatically from 1 week onward. Despite the very low metabolic rates in these species, larvae continued to swim and retained competence for at least 2 months. The capacity of non-feeding coral larvae to enter a state of low metabolism soon after becoming competent to metamorphose significantly extends dispersal potential, thereby accruing advantages typically associated with planktotrophy, notably enhanced population connectivity.

  19. Modelling larval transport in a axial convergence front

    NASA Astrophysics Data System (ADS)

    Robins, P.

    2010-12-01

    Marine larvae exhibit different vertical swimming behaviours, synchronised by factors such as tidal currents and daylight, in order to aid retention near the parent populations and hence promote production, avoid predation, or to stimulate digestion. This paper explores two types of larval migration in an estuarine axial convergent front which is an important circulatory mechanism in many coastal regions where larvae are concentrated. A parallelised, three-dimensional, ocean model was applied to an idealised estuarine channel which was parameterised from observations of an axial convergent front which occurs in the Conwy Estuary, U.K. (Nunes and Simpson, 1985). The model successfully simulates the bilateral cross-sectional recirculation of an axial convergent front, which has been attributed to lateral density gradients established by the interaction of the lateral shear of the longitudinal currents with the axial salinity gradients. On the flood tide, there is surface axial convergence whereas on the ebb tide, there is (weaker) surface divergence. Further simulations with increased/decreased tidal velocities and with stronger/weaker axial salinity gradients are planned so that the effects of a changing climate on the secondary flow can be understood. Three-dimensional Lagrangian Particle Tracking Models (PTMs) have been developed which use the simulated velocity fields to track larvae in the estuarine channel. The PTMs take into account the vertical migrations of two shellfish species that are commonly found in the Conwy Estuary: (i) tidal migration of the common shore crab (Carcinus maenas) and (ii), diel (daily) migration of the Great scallop (Pecten maximus). These migration behaviours are perhaps the most widespread amongst shellfish larvae and have been compared with passive (drifting) particles in order to assess their relative importance in terms of larval transport. Preliminary results suggest that the net along-estuary dispersal over a typical larval

  20. Live Cell Imaging of Butterfly Pupal and Larval Wings In Vivo

    PubMed Central

    Ohno, Yoshikazu; Otaki, Joji M.

    2015-01-01

    Butterfly wing color patterns are determined during the late larval and early pupal stages. Characterization of wing epithelial cells at these stages is thus critical to understand how wing structures, including color patterns, are determined. Previously, we successfully recorded real-time in vivo images of developing butterfly wings over time at the tissue level. In this study, we employed similar in vivo fluorescent imaging techniques to visualize developing wing epithelial cells in the late larval and early pupal stages 1 hour post-pupation. Both larval and pupal epithelial cells were rich in mitochondria and intracellular networks of endoplasmic reticulum, suggesting high metabolic activities, likely in preparation for cellular division, polyploidization, and differentiation. Larval epithelial cells in the wing imaginal disk were relatively large horizontally and tightly packed, whereas pupal epithelial cells were smaller and relatively loosely packed. Furthermore, larval cells were flat, whereas pupal cells were vertically elongated as deep as 130 μm. In pupal cells, many endosome-like or autophagosome-like structures were present in the cellular periphery down to approximately 10 μm in depth, and extensive epidermal feet or filopodia-like processes were observed a few micrometers deep from the cellular surface. Cells were clustered or bundled from approximately 50 μm in depth to deeper levels. From 60 μm to 80 μm in depth, horizontal connections between these clusters were observed. The prospective eyespot and marginal focus areas were resistant to fluorescent dyes, likely because of their non-flat cone-like structures with a relatively thick cuticle. These in vivo images provide important information with which to understand processes of epithelial cell differentiation and color pattern determination in butterfly wings. PMID:26107809

  1. Coexpression analysis of nine neuropeptides in the neurosecretory preoptic area of larval zebrafish

    PubMed Central

    Herget, Ulrich; Ryu, Soojin

    2015-01-01

    The paraventricular nucleus (PVN) of the hypothalamus in mammals coordinates neuroendocrine, autonomic and behavioral responses pivotal for homeostasis and the stress response. A large amount of studies in rodents has documented that the PVN contains diverse neuronal cell types which can be identified by the expression of distinct secretory neuropeptides. Interestingly, PVN cell types often coexpress multiple neuropeptides whose relative coexpression levels are subject to environment-induced plasticity. Due to their small size and transparency, zebrafish larvae offer the possibility to comprehensively study the development and plasticity of the PVN in large groups of intact animals, yet important anatomical information about the larval zebrafish PVN-homologous region has been missing. Therefore we recently defined the location and borders of the larval neurosecretory preoptic area (NPO) as the PVN-homologous region in larval zebrafish based on transcription factor expression and cell type clustering. To identify distinct cell types present in the larval NPO, we also generated a comprehensive 3D map of 9 zebrafish homologs of typical neuropeptides found in the mammalian PVN (arginine vasopressin (AVP), corticotropin-releasing hormone (CRH), proenkephalin a (penka)/b (penkb), neurotensin (NTS), oxytocin (OXT), vasoactive intestinal peptide (VIP), cholecystokinin (CCK), and somatostatin (SST)). Here we extend this chemoarchitectural map to include the degrees of coexpression of two neuropeptides in the same cell by performing systematic pairwise comparisons. Our results allowed the subclassification of NPO cell types, and differences in variability of coexpression profiles suggest potential targets of biochemical plasticity. Thus, this work provides an important basis for the analysis of the development, function, and plasticity of the primary neuroendocrine brain region in larval zebrafish. PMID:25729355

  2. Patterns of Larval Sucker Emigration from the Sprague and Lower Williamson Rivers of the Upper Klamath Basin, Oregon, Prior to the Removal of Chiloquin Dam - 2006 Annual Report

    USGS Publications Warehouse

    Ellsworth, Craig M.; Tyler, Torrey J.; VanderKooi, Scott P.; Markle, Douglas F.

    2009-01-01

    in larval drift at Chiloquin occurred approximately 1.5 to 2.0 hours after sunset. Nightly peak larval drift varied by location; larvae were captured earlier in the evening at sites closer to known spawning locations than sites farther away from these areas. The highest numerical catches of sucker-sized eggs were at Chiloquin indicating that this site is in close proximity to a spawning area. Numerical catches of older, more developed larval and juvenile suckers also were highest at Chiloquin. This may be due to the turbulent nature of this site, which could have swept larger fish into the drift. Proportional catches of older, more developed larval and juvenile suckers were highest at Sycan, Lone Pine, Power Station, and Fremont Bridge. This indicates these sites are located nearer to sucker nursery areas rather than spawning areas. Very few larval LRS were collected at Fremont Bridge at the south end of Upper Klamath Lake. Larval KLS-SNS densities at Fremont Bridge were the third highest of the seven sampling sites. Peak drift of larval KLS-SNS at Fremont Bridge occurred the week after peak drift of larval KLS-SNS at Williamson. Although inter-annual variation continues to appear in the larval drift data, our results continue to show consistent patterns of larval emigration in the drainage basin. In combination with data collected from the spawning movements and destinations of radio-tagged and PIT-tagged adult suckers, this larval drift data will provide a baseline standard by which to determine the effects of dam removal on the spawning distribution of endangered Klamath Basin suckers in the Sprague River.

  3. Effects of Tail Clipping on Larval Performance and Tail Regeneration Rates in the Near Eastern Fire Salamander, Salamandra infraimmaculata.

    PubMed

    Segev, Ori; Polevikove, Antonina; Blank, Lior; Goedbloed, Daniel; Küpfer, Eliane; Gershberg, Anna; Koplovich, Avi; Blaustein, Leon

    2015-01-01

    Tail-tip clipping is a common technique for collecting tissue samples from amphibian larvae and adults. Surprisingly, studies of this invasive sampling procedure or of natural tail clipping--i.e., bites inflicted by predators including conspecifics--on the performance and fitness of aquatic larval stages of urodeles are scarce. We conducted two studies in which we assessed the effects of posterior tail clipping (~30 percent of tail) on Near Eastern fire salamander (Salamandra infraimmaculata) larvae. In a laboratory study, we checked regeneration rates of posterior tail-tip clipping at different ages. Regeneration rates were hump-shaped, peaking at the age of ~30 days and then decreasing. This variation in tail regeneration rates suggests tradeoffs in resource allocation between regeneration and somatic growth during early and advanced development. In an outdoor artificial pond experiment, under constant larval densities, we assessed how tail clipping of newborn larvae affects survival to, time to, and size at metamorphosis. Repeated measures ANOVA on mean larval survival per pond revealed no effect of tail clipping. Tail clipping had correspondingly no effect on larval growth and development expressed in size (mass and snout-vent length) at, and time to, metamorphosis. We conclude that despite the given variation in tail regeneration rates throughout larval ontogeny, clipping of 30% percent of the posterior tail area seems to have no adverse effects on larval fitness and survival. We suggest that future use of this imperative tool for the study of amphibian should take into account larval developmental stage during the time of application and not just the relative size of the clipped tail sample. PMID:26065683

  4. Modelling larval movement data from individual bioassays.

    PubMed

    McLellan, Chris R; Worton, Bruce J; Deasy, William; Birch, A Nicholas E

    2015-05-01

    We consider modelling the movements of larvae using individual bioassays in which data are collected at a high-frequency rate of five observations per second. The aim is to characterize the behaviour of the larvae when exposed to attractant and repellent compounds. Mixtures of diffusion processes, as well as Hidden Markov models, are proposed as models of larval movement. These models account for directed and localized movements, and successfully distinguish between the behaviour of larvae exposed to attractant and repellent compounds. A simulation study illustrates the advantage of using a Hidden Markov model rather than a simpler mixture model. Practical aspects of model estimation and inference are considered on extensive data collected in a study of novel approaches for the management of cabbage root fly. PMID:25764283

  5. Effects of Larval Mosquitoes (Aedes triseriatus) and Stemflow on Microbial Community Dynamics in Container Habitats†

    PubMed Central

    Kaufman, Michael G.; Walker, Edward D.; Smith, Tracy W.; Merritt, Richard W.; Klug, Michael J.

    1999-01-01

    The dynamics of the microbial food sources for Aedes triseriatus larvae in microcosms were found to be strongly influenced by larval presence. The total abundance of bacteria in water samples generally increased in response to larvae, including populations of cultivable, facultatively anaerobic bacteria. Additionally, a portion of the community shifted from Pseudomonaceae to Enterobacteriaceae. Bacterial abundance on leaf material was significantly reduced in the presence of actively feeding larvae. Principle-component analysis of whole community fatty acid methyl ester (FAME) profiles showed that larvae changed the microbial community structure in both the water column and the leaf material. Cyclopropyl FAMEs, typically associated with bacteria, were reduced in microcosms containing larvae; however, other bacterial fatty acids showed no consistent response. Long-chain polyunsaturated fatty acids characteristic of microeukaryotes (protozoans and meiofauna) declined in abundance when larvae were present, indicating that larval feeding reduced the densities of these microorganisms. However, presumed fungal lipid markers either increased or were unchanged in response to larvae. Larval presence also affected microbial nitrogen metabolism through modification of the physiochemical conditions or by grazing on populations of bacteria involved in nitrification-denitrification. Stemflow primarily influenced inorganic ion and organic compound concentrations in the microcosms and had less-pronounced effects on microbial community parameters than did larval presence. Stemflow treatments diluted concentrations of all inorganic ions (chloride, sulfate, and ammonium) and organic compounds (total dissolved organic carbon, soluble carbohydrates, and total protein) measured, with the exceptions of nitrite and nitrate. Stemflow addition did not measurably affect larval biomass in the microcosms but did enhance development rates and early emergence patterns of adults. PMID:10347058

  6. Climate change and larval transport in the ocean: fractional effects from physical and physiological factors.

    PubMed

    Kendall, Matthew S; Poti, Matt; Karnauskas, Kristopher B

    2016-04-01

    Changes in larval import, export, and self-seeding will affect the resilience of coral reef ecosystems. Climate change will alter the ocean currents that transport larvae and also increase sea surface temperatures (SST), hastening development, and shortening larval durations. Here, we use transport simulations to estimate future larval connectivity due to: (1) physical transport of larvae from altered circulation alone, and (2) the combined effects of altered currents plus physiological response to warming. Virtual larvae from islands throughout Micronesia were moved according to present-day and future ocean circulation models. The Hybrid Coordinate Ocean Model (HYCOM) spanning 2004-2012 represented present-day currents. For future currents, we altered HYCOM using analysis from the National Center for Atmospheric Research Community Earth System Model, version 1-Biogeochemistry, Representative Concentration Pathway 8.5 experiment. Based on the NCAR model, regional SST is estimated to rise 2.74 °C which corresponds to a ~17% decline in larval duration for some taxa. This reduction was the basis for a separate set of simulations. Results predict an increase in self-seeding in 100 years such that 62-76% of islands experienced increased self-seeding, there was an average domainwide increase of ~1-3% points in self-seeding, and increases of up to 25% points for several individual islands. When changed currents alone were considered, approximately half (i.e., random) of all island pairs experienced decreased connectivity but when reduced PLD was added as an effect, ~65% of connections were weakened. Orientation of archipelagos relative to currents determined the directional bias in connectivity changes. There was no universal relationship between climate change and connectivity applicable to all taxa and settings. Islands that presently export large numbers of larvae but that also maintain or enhance this role into the future should be the focus of conservation

  7. The Drosophila larval visual system: high-resolution analysis of a simple visual neuropil.

    PubMed

    Sprecher, Simon G; Cardona, Albert; Hartenstein, Volker

    2011-10-01

    The task of the visual system is to translate light into neuronal encoded information. This translation of photons into neuronal signals is achieved by photoreceptor neurons (PRs), specialized sensory neurons, located in the eye. Upon perception of light the PRs will send a signal to target neurons, which represent a first station of visual processing. Increasing complexity of visual processing stems from the number of distinct PR subtypes and their various types of target neurons that are contacted. The visual system of the fruit fly larva represents a simple visual system (larval optic neuropil, LON) that consists of 12 PRs falling into two classes: blue-senstive PRs expressing Rhodopsin 5 (Rh5) and green-sensitive PRs expressing Rhodopsin 6 (Rh6). These afferents contact a small number of target neurons, including optic lobe pioneers (OLPs) and lateral clock neurons (LNs). We combine the use of genetic markers to label both PR subtypes and the distinct, identifiable sets of target neurons with a serial EM reconstruction to generate a high-resolution map of the larval optic neuropil. We find that the larval optic neuropil shows a clear bipartite organization consisting of one domain innervated by PRs and one devoid of PR axons. The topology of PR projections, in particular the relationship between Rh5 and Rh6 afferents, is maintained from the nerve entering the brain to the axon terminals. The target neurons can be subdivided according to neurotransmitter or neuropeptide they use as well as the location within the brain. We further track the larval optic neuropil through development from first larval instar to its location in the adult brain as the accessory medulla. PMID:21781960

  8. The Drosophila larval visual system: high-resolution analysis of a simple visual neuropil

    PubMed Central

    Sprecher, Simon G.; Cardona, Albert; Hartenstein, Volker

    2012-01-01

    The task of the visual system is to translate light into neuronal encoded information. This translation of photons into neuronal signals is achieved by photoreceptor neurons (PRs), specialized sensory neurons, located in the eye. Upon perception of light the PRs will send a signal to target neurons, which represent a first station of visual processing. Increasing complexity of visual processing stems from the number of distinct PR-subtypes and their various types of target neurons that are contacted. The visual system of the fruit fly larva represents a simple visual system (larval optic neuropil, LON) that consists of 12 PRs falling into two classes: blue-senstive PRs expressing Rhodopsin 5 (Rh5) and green-sensitive PRs expressing Rhodopsin 6 (Rh6). These afferents contact a small number of target neurons, including optic lobe pioneers (OLPs) and lateral clock neurons (LNs). We combine the use of genetic markers to label both PR-subtypes and the distinct, identifiable sets of target neurons with a serial EM reconstruction to generate a high-resolution map of the larval optic neuropil. We find that the larval optic neuropil shows a clear bipartite organization consisting of one domain innervated by PRs and one devoid of PR axons. The topology of PR projections, in particular the relationship between Rh5 and Rh6 afferents, is maintained from the nerve entering the brain to the axon terminals. The target neurons can be subdivided according to neurotransmitter or neuropeptide they use as well as the location within the brain. We further track the larval optic neuropil through development from first larval instar to its location in the adult brain as the accessory medulla. PMID:21781960

  9. Larval Exposure to the Juvenile Hormone Analog Pyriproxyfen Disrupts Acceptance of and Social Behavior Performance in Adult Honeybees

    PubMed Central

    Fourrier, Julie; Deschamps, Matthieu; Droin, Léa; Alaux, Cédric; Fortini, Dominique; Beslay, Dominique; Le Conte, Yves; Devillers, James; Aupinel, Pierrick; Decourtye, Axel

    2015-01-01

    Background Juvenile hormone (JH) plays an important role in honeybee development and the regulation of age-related division of labor. However, honeybees can be exposed to insect growth regulators (IGRs), such as JH analogs developed for insect pest and vector control. Although their side effects as endocrine disruptors on honeybee larval or adult stages have been studied, little is known about the subsequent effects on adults of a sublethal larval exposure. We therefore studied the impact of the JH analog pyriproxyfen on larvae and resulting adults within a colony under semi-field conditions by combining recent laboratory larval tests with chemical analysis and behavioral observations. Oral and chronic larval exposure at cumulative doses of 23 or 57 ng per larva were tested. Results Pyriproxyfen-treated bees emerged earlier than control bees and the highest dose led to a significant rate of malformed adults (atrophied wings). Young pyriproxyfen-treated bees were more frequently rejected by nestmates from the colony, inducing a shorter life span. This could be linked to differences in cuticular hydrocarbon (CHC) profiles between control and pyriproxyfen-treated bees. Finally, pyriproxyfen-treated bees exhibited fewer social behaviors (ventilation, brood care, contacts with nestmates or food stocks) than control bees. Conclusion Larval exposure to sublethal doses of pyriproxyfen affected several life history traits of the honeybees. Our results especially showed changes in social integration (acceptance by nestmates and social behaviors performance) that could potentially affect population growth and balance of the colony. PMID:26171610

  10. Mutation of a Cuticular Protein, BmorCPR2, Alters Larval Body Shape and Adaptability in Silkworm, Bombyx mori

    PubMed Central

    Qiao, Liang; Xiong, Gao; Wang, Ri-xin; He, Song-zhen; Chen, Jie; Tong, Xiao-ling; Hu, Hai; Li, Chun-lin; Gai, Ting-ting; Xin, Ya-qun; Liu, Xiao-fan; Chen, Bin; Xiang, Zhong-huai; Lu, Cheng; Dai, Fang-yin

    2014-01-01

    Cuticular proteins (CPs) are crucial components of the insect cuticle. Although numerous genes encoding cuticular proteins have been identified in known insect genomes to date, their functions in maintaining insect body shape and adaptability remain largely unknown. In the current study, positional cloning led to the identification of a gene encoding an RR1-type cuticular protein, BmorCPR2, highly expressed in larval chitin-rich tissues and at the mulberry leaf-eating stages, which is responsible for the silkworm stony mutant. In the Dazao-stony strain, the BmorCPR2 allele is a deletion mutation with significantly lower expression, compared to the wild-type Dazao strain. Dysfunctional BmorCPR2 in the stony mutant lost chitin binding ability, leading to reduced chitin content in larval cuticle, limitation of cuticle extension, abatement of cuticle tensile properties, and aberrant ratio between internodes and intersegmental folds. These variations induce a significant decrease in cuticle capacity to hold the growing internal organs in the larval development process, resulting in whole-body stiffness, tightness, and hardness, bulging intersegmental folds, and serious defects in larval adaptability. To our knowledge, this is the first study to report the corresponding phenotype of stony in insects caused by mutation of RR1-type cuticular protein. Our findings collectively shed light on the specific role of cuticular proteins in maintaining normal larval body shape and will aid in the development of pest control strategies for the management of Lepidoptera. PMID:24514903

  11. Mutation of a cuticular protein, BmorCPR2, alters larval body shape and adaptability in silkworm, Bombyx mori.

    PubMed

    Qiao, Liang; Xiong, Gao; Wang, Ri-xin; He, Song-zhen; Chen, Jie; Tong, Xiao-ling; Hu, Hai; Li, Chun-lin; Gai, Ting-ting; Xin, Ya-qun; Liu, Xiao-fan; Chen, Bin; Xiang, Zhong-huai; Lu, Cheng; Dai, Fang-yin

    2014-04-01

    Cuticular proteins (CPs) are crucial components of the insect cuticle. Although numerous genes encoding cuticular proteins have been identified in known insect genomes to date, their functions in maintaining insect body shape and adaptability remain largely unknown. In the current study, positional cloning led to the identification of a gene encoding an RR1-type cuticular protein, BmorCPR2, highly expressed in larval chitin-rich tissues and at the mulberry leaf-eating stages, which is responsible for the silkworm stony mutant. In the Dazao-stony strain, the BmorCPR2 allele is a deletion mutation with significantly lower expression, compared to the wild-type Dazao strain. Dysfunctional BmorCPR2 in the stony mutant lost chitin binding ability, leading to reduced chitin content in larval cuticle, limitation of cuticle extension, abatement of cuticle tensile properties, and aberrant ratio between internodes and intersegmental folds. These variations induce a significant decrease in cuticle capacity to hold the growing internal organs in the larval development process, resulting in whole-body stiffness, tightness, and hardness, bulging intersegmental folds, and serious defects in larval adaptability. To our knowledge, this is the first study to report the corresponding phenotype of stony in insects caused by mutation of RR1-type cuticular protein. Our findings collectively shed light on the specific role of cuticular proteins in maintaining normal larval body shape and will aid in the development of pest control strategies for the management of Lepidoptera. PMID:24514903

  12. Dimethylsulfoniopropionate (DMSP) Increases Survival of Larval Sablefish, Anoplopoma fimbria.

    PubMed

    Lee, Jonathan S F; Poretsky, Rachel S; Cook, Matthew A; Reyes-Tomassini, Jose J; Berejikian, Barry A; Goetz, Frederick W

    2016-06-01

    High concentrations of dimethylsulfoniopropionate (DMSP), a chemical compound released by lysed phytoplankton, may indicate high rates of grazing by zooplankton and may thus be a foraging cue for planktivorous fishes. Previous studies have shown that some planktivorous fishes and birds aggregate or alter locomotory behavior in response to this chemical cue, which is likely adaptive because it helps them locate prey. These behavioral responses have been demonstrated in juveniles and adults, but no studies have tested for effects on larval fish. Larvae suffer from high mortality rates and are vulnerable to starvation. While larvae are generally thought to be visual predators, they actually have poor vision and cryptic prey. Thus, larval fish should benefit from a chemical cue that provides information on prey abundance. We reared larval sablefish, Anoplopoma fimbria, for one week and supplemented feedings with varying concentrations of DMSP to test the hypothesis that DMSP affects larval survival. Ecologically relevant DMSP concentrations increased larval survival by up to 70 %, which has implications for production in aquaculture and recruitment in nature. These results provide a new tool for increasing larval production in aquaculture and also suggest that larvae may use DMSP as an olfactory cue. The release of DMSP may be a previously unappreciated mechanism through which phytoplankton affect larval survival and recruitment. PMID:27306913

  13. Fisheries Closed Areas Strengthen Scallop Larval Settlement and Connectivity Among Closed Areas and Across International Open Fishing Grounds: A Model Study

    NASA Astrophysics Data System (ADS)

    Davies, Kimberley T. A.; Gentleman, W. C.; DiBacco, C.; Johnson, C. L.

    2015-09-01

    This study examined whether a measured increase in average body size of adult sea scallops inside three fishery closed areas on Georges Bank (GB), United States (US), was sufficient to increase larval supply to closed areas and open fishing areas in both US and Canadian areas of the Bank. The effects of adult scallop density-at-size and fecundity-at-size on egg production were compared among open and closed fishery areas, countries, and time periods before and after the closed areas were established. Estimated egg production was then used to define spawning conditions in a coupled biological-physical larval tracking model that simulated larval development, mortality, and dispersal. Results showed that order of magnitude increases in larval settlement after closure were facilitated by increases in size-dependant egg production inside and dispersal from Closed Areas I and II, but not Nantucket Lightship Closed Area. The distributions of both egg production and larval settlement became more uniform across the Bank, causing the relative contribution of Canadian larvae to US scallop aggregations to decrease after establishment of Closed Areas I and II. Decreases in small and medium-sized scallop density in Canada and decreases in large scallops over the US-Southern Flank after closure caused local declines in egg production but were not sufficient to negatively affect larval settlement at the regional scale. Our model suggests that the establishment of fishery closed areas on GB considerably strengthened larval supply and settlement within and among several adult scallop aggregations.

  14. Diamondback Moth (Lepidoptera: Plutellidae) Exhibits Oviposition and Larval Feeding Preferences Among Crops, Wild plants, and Ornamentals as Host Plants.

    PubMed

    Newman, K; You, M; Vasseur, L

    2016-04-01

    Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an agricultural pest with high reproductive potential, widespread distribution, and high resistance to different types of insecticides. Although diamondback moth is a common research subject, questions remain regarding its spatial and temporal host plant usage patterns and preferences within agroecosystems. We examined the adult oviposition and larval feeding preferences of the diamondback moth to assess the potential of alternate host plants as either reservoirs or trap crops. Adult females and third and fourth instars were offered multiple plant species within the plant family Brassicaceae to examine contact preferences and larval ingestion rates. Adult oviposition and larval feeding preferences were identical, with garden cress (Lepidium sativum) (L.) highly preferred, followed by wintercress (Barbarea vulgaris) (L.) and black mustard (Brassica nigra) (L.). Ingestion rates varied among tested plants, with the lowest rate on black mustard and highest on aubretia (Aubretia deltoidea) (L.). Highly preferred plant species were determined to be unfavorable for larval growth and potentially lethal to neonates, suggesting their possible use as trap crops. Understanding ovipositional and larval feeding preferences of diamondback moth can also aid in the development of more accurate monitoring and control strategies for this pest. PMID:26834144

  15. Foraging and predation risk for larval cisco (Coregonus artedi) in Lake Superior: a modelling synthesis of empirical survey data

    USGS Publications Warehouse

    Myers, Jared T.; Yule, Daniel L.; Jones, Michael L.; Quinlan, Henry R.; Berglund, Eric K.

    2014-01-01

    The relative importance of predation and food availability as contributors to larval cisco (Coregonus artedi) mortality in Lake Superior were investigated using a visual foraging model to evaluate potential predation pressure by rainbow smelt (Osmerus mordax) and a bioenergetic model to evaluate potential starvation risk. The models were informed by observations of rainbow smelt, larval cisco, and zooplankton abundance at three Lake Superior locations during the period of spring larval cisco emergence and surface-oriented foraging. Predation risk was highest at Black Bay, ON, where average rainbow smelt densities in the uppermost 10 m of the water column were >1000 ha−1. Turbid conditions at the Twin Ports, WI-MN, affected larval cisco predation risk because rainbow smelt remained suspended in the upper water column during daylight, placing them alongside larval cisco during both day and night hours. Predation risk was low at Cornucopia, WI, owing to low smelt densities (<400 ha−1) and deep light penetration, which kept rainbow smelt near the lakebed and far from larvae during daylight. In situ zooplankton density estimates were low compared to the values used to develop the larval coregonid bioenergetics model, leading to predictions of negative growth rates for 10 mm larvae at all three locations. The model predicted that 15 mm larvae were capable of attaining positive growth at Cornucopia and the Twin Ports where low water temperatures (2–6 °C) decreased their metabolic costs. Larval prey resources were highest at Black Bay but warmer water temperatures there offset the benefit of increased prey availability. A sensitivity analysis performed on the rainbow smelt visual foraging model showed that it was relatively insensitive, while the coregonid bioenergetics model showed that the absolute growth rate predictions were highly sensitive to input parameters (i.e., 20% parameter perturbation led to order of magnitude differences in model estimates). Our

  16. Behavioral analysis of the escape response in larval zebrafish

    NASA Astrophysics Data System (ADS)

    Feng, Ruopei; Girdhar, Kiran; Chemla, Yann; Gruebele, Martin

    The behavior of larval zebrafish is of great interest because the limited number of locomotor neurons in larval zebrafish couples with its rich repertoire of movements as a vertebrate animal. Current research uses a priori-selected parameters to describe their swimming behavior while our lab has built a parameter-free model based on singular value decomposition analysis to characterize it. Our previous work has analyzed the free swimming of larval zebrafish and presented a different picture from the current classification of larval zebrafish locomotion. Now we are extending this work to the studies of their escape response to acoustic stimulus. Analysis has shown intrinsic difference in the locomotion between escape response and free swimming.

  17. Larval adaptations and patterns of brachiopod diversity in space and time

    NASA Technical Reports Server (NTRS)

    Valentine, J. W.; Jablonski, D.

    1983-01-01

    Modern biodistributional patterns suggest that modes of larval development are a factor in determining the patterns of diversity in benthic invertebrates. Paleozoic brachiopods had diversity patterns suggesting that they possessed both planktotrophic and nonplanktotrophic modes. It is presently hypothesized that the planktotrophic lineages were lost to extinction, largely or entirely during the Permian-Triassic event, and that the failure of the articulate brachiopods to regain their former importance is substantially due to their nonplanktotrophic developmental mode.

  18. Effect of Dietary Components on Larval Life History Characteristics in the Medfly (Ceratitis capitata: Diptera, Tephritidae)

    PubMed Central

    Nash, William J.; Chapman, Tracey

    2014-01-01

    Background The ability to respond to heterogenous nutritional resources is an important factor in the adaptive radiation of insects such as the highly polyphagous Medfly. Here we examined the breadth of the Medfly’s capacity to respond to different developmental conditions, by experimentally altering diet components as a proxy for host quality and novelty. Methodology/Principal Findings We tested responses of larval life history to diets containing protein and carbohydrate components found in and outside the natural host range of this species. A 40% reduction in the quantity of protein caused a significant increase in egg to adult mortality by 26.5%±6% in comparison to the standard baseline diet. Proteins and carbohydrates had differential effects on larval versus pupal development and survival. Addition of a novel protein source, casein (i.e. milk protein), to the diet increased larval mortality by 19.4%±3% and also lengthened the duration of larval development by 1.93±0.5 days in comparison to the standard diet. Alteration of dietary carbohydrate, by replacing the baseline starch with simple sugars, increased mortality specifically within the pupal stage (by 28.2%±8% and 26.2%±9% for glucose and maltose diets, respectively). Development in the presence of the novel carbohydrate lactose (milk sugar) was successful, though on this diet there was a decrease of 29.8±1.6 µg in mean pupal weight in comparison to pupae reared on the baseline diet. Conclusions The results confirm that laboratory reared Medfly retain the ability to survive development through a wide range of fluctuations in the nutritional environment. We highlight new facets of the responses of different stages of holometabolous life histories to key dietary components. The results are relevant to colonisation scenarios and key to the biology of this highly invasive species. PMID:24465851

  19. Exposure to waterborne Cu inhibits cutaneous Na⁺ uptake in post-hatch larval rainbow trout (Oncorhynchus mykiss).

    PubMed

    Zimmer, Alex M; Brauner, Colin J; Wood, Chris M

    2014-05-01

    In freshwater rainbow trout (Oncorhynchus mykiss), two common responses to acute waterborne copper (Cu) exposure are reductions in ammonia excretion and Na(+) uptake at the gills, with the latter representing the likely lethal mechanism of action for Cu in adult fish. Larval fish, however, lack a functional gill following hatch and rely predominantly on cutaneous exchange, yet represent the most Cu-sensitive life stage. It is not known if Cu toxicity in larval fish occurs via the skin or gills. The present study utilized divided chambers to assess cutaneous and branchial Cu toxicity over larval development, using disruptions in ammonia excretion (Jamm) and Na(+) uptake (Jin(Na)) as toxicological endpoints. Early in development (early; 3 days post-hatch; dph), approximately 95% of Jamm and 78% of Jin(Na) occurred cutaneously, while in the late developmental stage (late; 25 dph), the gills were the dominant site of exchange (83 and 87% of Jamm and Jin(Na), respectively). Exposure to 50 μg/l Cu led to a 49% inhibition of Jamm in the late developmental stage only, while in the early and middle developmental (mid; 17 dph) stages, Cu had no effect on Jamm. Jin(Na), however, was significantly inhibited by Cu exposure at the early (53% reduction) and late (47% reduction) stages. Inhibition at the early stage of development was mediated by a reduction in cutaneous uptake, representing the first evidence of cutaneous metal toxicity in an intact aquatic organism. The inhibitions of both Jamm and Jin(Na) in the late developmental stage occurred via a reduction in branchial exchange only. The differential responses of the skin and gills to Cu exposure suggest that the mechanisms of Jamm and Jin(Na) and/or Cu toxicity differ between these tissues. Exposure to 20μg/l Cu revealed that Jamm is the more Cu-sensitive process. The results presented here have important implications in predicting metal toxicity in larval fish. The Biotic Ligand Model (BLM) is currently used to predict

  20. Reduction of a larval herring population by jellyfish predator.

    PubMed

    Möller, H

    1984-05-11

    The scyphomedusa Aurelia aurita consumes large amounts of yolk-sac herring larvae in Kiel Fjord. The decline of the larval herring population in late spring coincides with a major population growth of the jellyfish. The size of the larval herring population seems to be more significantly affected by the size of the predator stock than by the size of the parental herring stock. PMID:17838355

  1. Density-Dependent Intraspecific Competition in the Larval Stage of Aedes aegypti (Diptera: Culicidae): Revisiting the Current Paradigm

    PubMed Central

    Legros, Mathieu; Lloyd, Alun L.; Huang, Yunxin; Gould, Fred

    2009-01-01

    Density-dependent intraspecific competition has been considered an important determinant of the dynamics of larval stages of Aedes aegypti. A model was published in 1984 providing a mathematical description of this density dependence, based on field data, that has since been widely used. This description, however, is based on the strong assumption that all mortality is density-dependent. We re-examine the data without this premise and find a reduced importance of density dependence, as well as a different functional form. Based on these discrepancies, we emphasize that the characterization of density dependence in the larval stages of Ae. aegypti should be based on a more complete dataset, and we use artificially generated data to explore how such additional information could help developing a better description of this density dependence. We review other empirical studies on larval competition, discuss the need for further dedicated studies, and provide a few simple guidelines for the design of such studies. PMID:19496407

  2. Imaging fictive locomotor patterns in larval Drosophila

    PubMed Central

    Bayley, Timothy G.; Taylor, Adam L.; Berni, Jimena; Bate, Michael; Hedwig, Berthold

    2015-01-01

    We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca2+ indicators. The Ca2+ signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca2+ signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca2+ signals were normally initiated did not eliminate production of Ca2+ waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques. PMID:26311188

  3. Basic Gravitational Reflexes in the Larval Frog

    NASA Technical Reports Server (NTRS)

    Cochran, Stephen L.

    1996-01-01

    This investigation was designed to determine how a primitive vertebrate, the bullfrog tadpole, is able to sense and process gravitational stimuli. Because of the phylogenetic similarities of the vestibular systems in all vertebrates, the understanding of the gravitational reflexes in this relatively simple vertebrate should elucidate a skeletal framework on a elementary level, upon which the more elaborate reflexes of higher vertebrates may be constructed. The purpose of this study was to understand how the nervous system of the larval amphibian processes gravitational information. This study involved predominantly electrophysiological investigations of the isolated, alert (forebrain removed) bullfrog tadpole head. The focus of these experiments is threefold: (1) to understand from whole extraocular nerve recordings the signals sent to the eye following static gravitational tilt of the head; (2) to localize neuronal centers responsible for generating these signals through reversible pharmacological ablation of these centers; and (3) to record intracellularly from neurons within these centers in order to determine the single neuron's role in the overall processing of the center. This study has provided information on the mechanisms by which a primitive vertebrate processes gravitational reflexes.

  4. Imaging fictive locomotor patterns in larval Drosophila.

    PubMed

    Pulver, Stefan R; Bayley, Timothy G; Taylor, Adam L; Berni, Jimena; Bate, Michael; Hedwig, Berthold

    2015-11-01

    We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca(2+) indicators. The Ca(2+) signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca(2+) signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca(2+) signals were normally initiated did not eliminate production of Ca(2+) waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques. PMID:26311188

  5. Dissection of larval CNS in Drosophila melanogaster.

    PubMed

    Hafer, Nathaniel; Schedl, Paul

    2006-12-01

    The central nervous system (CNS) of Drosophila larvae is complex and poorly understood. One way to investigate the CNS is to use immunohistochemistry to examine the expression of various novel and marker proteins. Staining of whole larvae is impractical because the tough cuticle prevents antibodies from penetrating inside the body cavity. In order to stain these tissues it is necessary to dissect the animal prior to fixing and staining. In this article we demonstrate how to dissect Drosophila larvae without damaging the CNS. Begin by tearing the larva in half with a pair of fine forceps, and then turn the cuticle "inside-out" to expose the CNS. If the dissection is performed carefully the CNS will remain attached to the cuticle. We usually keep the CNS attached to the cuticle throughout the fixation and staining steps, and only completely remove the CNS from the cuticle just prior to mounting the samples on glass slides. We also show some representative images of a larval CNS stained with Eve, a transcription factor expressed in a subset of neurons in the CNS. The article concludes with a discussion of some of the practical uses of this technique and the potential difficulties that may arise. PMID:18704179

  6. Autophagy precedes apoptosis during the remodeling of silkworm larval midgut.

    PubMed

    Franzetti, Eleonora; Huang, Zhi-Jun; Shi, Yan-Xia; Xie, Kun; Deng, Xiao-Juan; Li, Jian-Ping; Li, Qing-Rong; Yang, Wan-Ying; Zeng, Wen-Nian; Casartelli, Morena; Deng, Hui-Min; Cappellozza, Silvia; Grimaldi, Annalisa; Xia, Qingyou; Feng, Qili; Cao, Yang; Tettamanti, Gianluca

    2012-03-01

    Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis, solid experimental evidence for autophagy is still lacking. Moreover, the role of the two processes and the nature of their relationship are still cryptic. In this study, we perform a cellular, biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation, with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions. We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms, which occur at different times and have different functions. Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages, as demonstrated by specific autophagic markers. Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period. Apoptosis intervenes later. In fact, although genes encoding caspases are transcribed at the end of the larval period, the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase. The abundance of apoptotic features during the pupal phase, when the majority of the cells die, indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells. PMID:22127643

  7. Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny

    PubMed Central

    Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

    2015-01-01

    Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential

  8. Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny.

    PubMed

    Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

    2015-01-01

    Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential

  9. Comparison of alpha-amylase activity in larval stages of flour beetles, Tribolium confusum (Coleoptera: Tenebionidae).

    PubMed

    Bandani, A R; Balvasi, A

    2006-01-01

    Flour beetles attack stored grain products such as flour, cereals, meal, dried pet food, dried flowers and even dried museum specimens and other foods in the house. Stored-product insects cause tremendous losses by lowering weight, germination rate, nutritional value and grain grade. These beetles are of the most important pests of stored products in the home and grocery stores. The adult female may live for as long as two years, depositing 300 to 400 eggs. The life cycle requires one to four months when temperatures are favorable. Several methods could be used to control this insect including synthetic insecticides, biological control, physical control and transgenic plant carrying gene of interest. Chemical controls are discouraged due to pesticide residue in the commodities and resistance in insects. The study of insect digestive enzymes seems to make sense in the realization that the gut is the major interface between the insect and its environment. Hence, an understanding of digestive enzyme function is essential when developing methods of insect control such as the use of enzyme inhibitors and transgenic plants to control insect pests. Therefore, the aim of the current study was to get a good understanding from enzyme composition of different larval stages of the insect and finally characterize amylase which is the key enzyme in digestive system of this insect. For alpha-amylase study whole larvae were homogenized in 0.02 M phosphate buffer at pH 7.2. The homogenates were separately transferred to a 1.5 ml of centrifuge tubes and centrifuged at 15000xg for 20 min at 4degrees C. The supernatants were used as enzyme source in assays. alpha-Amylase activity was assayed by the dinitrosalicylic acid (DNS) procedure using 1% soluble starch (Merck) as substrate. The results show that enzyme activity (OD) in the first, second, third and fourth larval stages were 0.5, 1.15, 1.35 and 1.362, respectively. There are significant differences in amylase activity in

  10. Effect of temperature on feeding period of larval blacklegged ticks (Acari: Ixodidae) on eastern fence lizards

    USGS Publications Warehouse

    Rulison, Eric L.; LeBrun, Roger A.; Ginsberg, Howard S.

    2014-01-01

    Ambient temperature can influence tick development time, and can potentially affect tick interactions with pathogens and with vertebrate hosts. We studied the effect of ambient temperature on duration of attachment of larval blacklegged ticks, Ixodes scapularis Say, to eastern fence lizards, Sceloporus undulatus (Bose & Daudin). Feeding periods of larvae that attached to lizards under preferred temperature conditions for the lizards (WARM treatment: temperatures averaged 36.6°C at the top of the cage and 25.8°C at the bottom, allowing behavioral thermoregulation) were shorter than for larvae on lizards held under cool conditions (COOL treatment temperatures averaged 28.4°C at top of cage and 24.9°C at the bottom). The lizards were infested with larvae four times at roughly monthly intervals. Larval numbers successfully engorging and dropping declined and feeding period was longer after the first infestation.

  11. An Optimized Whole-Body Cortisol Quantification Method for Assessing Stress Levels in Larval Zebrafish

    PubMed Central

    Yeh, Chen-Min; Glöck, Mario; Ryu, Soojin

    2013-01-01

    Glucocorticoids serve important regulatory functions for many physiological processes and are critical mediators of the stress response. The stress response is a set of bodily processes aimed at counteracting a state of threatened homeostasis. Proper stress response is critical for the survival of an animal, however prolonged or abnormal stress response can be detrimental and is implicated in a number of human diseases such as depression and metabolic diseases. To dissect the underlying mechanism of this complex and important response, the zebrafish, Danio rerio offer important advantages such as ease of genetic manipulations and high-throughput behavioral analyses. However, there is a paucity of suitable methods to measure stress level in larval zebrafish. Therefore, an efficient low-cost method to monitor stress hormone levels will greatly facilitate stress research in zebrafish larvae. In this study, we optimized sample collection as well as cortisol extraction methods and developed a home-made ELISA protocol for measuring whole-body cortisol level in zebrafish larvae. Further, using our customized protocols, we characterized the response of larval zebrafish to a variety of stressors. This assay, developed for efficient cortisol quantification, will be useful for systematic and large-scale stress analyses in larval zebrafish. PMID:24223943

  12. Drift dynamics of larval pallid sturgeon and shovelnose sturgeon in a natural side channel of the Upper Missouri River, Montana

    USGS Publications Warehouse

    Braaten, P.J.; Fuller, D.B.; Holte, L.D.; Lott, R.D.; Viste, W.; Brandt, T.F.; Legare, R.G.

    2008-01-01

    The drift dynamics of larval shovelnose sturgeon Scaphirhynchus platorynchus (1, 2, 6, and 10 d posthatch [dph]) and pallid sturgeon S. albus (1, 2, 5, 9, 11, and 17 dph) were examined in a natural side channel of the Missouri River to quantify the vertical drift location of larvae in the water column, determine the drift velocity of larvae relative to water velocity, and simulate the cumulative distance (km) drifted by larvae during ontogenetic development. Larvae were released at the side-channel inlet and sampled at points 100, 500, 900, and 1,300 m downstream. Larvae drifted primarily near the riverbed, as 58-79% of recaptured shovelnose sturgeon and 63-89% of recaptured pallid sturgeon were sampled in the lower 0.5 m of the water column. The transition from the drifting to the benthic life stage was initiated at 6 dph (mean length, 15.6 mm) for shovelnose sturgeon and at 11-17 dph (mean length, 18.1-20.3 mm) for pallid sturgeon. Across ages, the drift rates of larval shovelnose sturgeon averaged 0.09-0.16 m/s slower than the mean water column velocity. The drift rates of pallid sturgeon were similar to or slightly slower (0.03-0.07 m/s) than the mean water column velocity for 1-11-dph larvae. Conversely, 17-dph larval pallid sturgeon dispersed downstream at a much slower rate (mean, 0.20 m/s slower than the mean water column velocity) owing to their transition to benthic habitats. Drift simulations indicated that the average larval shovelnose sturgeon may drift from 94 to 250 km and the average larval pallid sturgeon may drift from 245 to 530 km, depending on water velocity. Differences in larval drift dynamics between species provide a possible explanation for differences in recruitment between shovelnose sturgeon and pallid sturgeon in the upper Missouri River. ?? Copyright by the American Fisheries Society 2008.

  13. Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales

    USGS Publications Warehouse

    Torgersen, Christian E.; Close, David A.

    2004-01-01

    1. Spatial patterns in channel morphology and substratum composition at small (1a??10 metres) and large scales (1a??10 kilometres) were analysed to determine the influence of habitat heterogeneity on the distribution and abundance of larval lamprey. 2. We used a nested sampling design and multiple logistic regression to evaluate spatial heterogeneity in the abundance of larval Pacific lamprey, Lampetra tridentata, and habitat in 30 sites (each composed of twelve 1-m2 quadrat samples) distributed throughout a 55-km section of the Middle Fork John Day River, OR, U.SA. Statistical models predicting the relative abundance of larvae both among sites (large scale) and among samples (small scale) were ranked using Akaike's Information Criterion (AIC) to identify the 'best approximating' models from a set of a priori candidate models determined from the literature on larval lamprey habitat associations. 3. Stream habitat variables predicted patterns in larval abundance but played different roles at different spatial scales. The abundance of larvae at large scales was positively associated with water depth and open riparian canopy, whereas patchiness in larval occurrence at small scales was associated with low water velocity, channel-unit morphology (pool habitats), and the availability of habitat suitable for burrowing. 4. Habitat variables explained variation in larval abundance at large and small scales, but locational factors, such as longitudinal position (river km) and sample location within the channel unit, explained additional variation in the logistic regression model. The results emphasise the need for spatially explicit analysis, both in examining fish habitat relationships and in developing conservation plans for declining fish populations.

  14. Nectar and pollen sugars constituting larval provisions of the alfalfa leaf-cutting bee (Megachile rotundata) (Hymenoptera: Apiformes: Megachilidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As with most solitary bees, larvae of the alfalfa leaf-cutting bee, Megachile rotundata Fab., eat a diet blended from pollen and nectar of unknown proportions. In this study, we developed protocols to isolate and quantify sugars from larval provision masses. The method removed free amino acids tha...

  15. COMPARATIVE EMBRYONIC AND LARVAL DEVELOPMENTAL RESPONSES OF AN ESTUARINE SHRIMP (PALAEMONETES PUGIO) TO THE JUVENILE HORMONE AGONIST, FENOXYCARB.

    EPA Science Inventory

    Grass shrimp (Palaemonetes pugio) were reared separately through both embryonic and total larval development during exposure to fenoxycarb at measured concentrations of <2.2 to 888 ug L-1. A fenoxycarb concentration of 888 ug L-1significantly (p<0.05) inhibited embryonic developm...

  16. On the morphology of the central nervous system in larval stages of Carcinus maenas L. (Decapoda, Brachyura)

    NASA Astrophysics Data System (ADS)

    Harzsch, S.; Dawirs, R. R.

    1993-02-01

    We investigated the morphology of the central nervous system throughout the larval development of Carcinus maenas. For that purpose single larvae were reared in the laboratory from hatching through metamorphosis. Complete series of whole mout semithin sections were obtained from individuals of all successive larval stages and analysed with a light microscope. Morphological feature and spatial arrangement of discernable neural cell clusters, fibre tracts and neuropile are described and compared with the adult pattern. We found that most of the morphological features characterizing the adult nervous system are already present in the zoea-1. Nevertheless, there are marked differences with respect to the arrangement of nerve cell bodies, organization of cerebral neuropile, and disposition of ganglia in the ventral nerve cord. It appears that complexity of the central nervous neuropile is selectively altered during postmetamorphotic development, probably reflecting adaptive changes of sensory-motor integration in response to behavioural maturation. In contrast, during larval development there was little change in the overall structural organization of the central nervous system despite some considerable growth. However, the transition from zoea-4 to megalopa brings about multiple fundamental changes in larval morphology and behavioural pattern. Since central nervous integration should properly adapt to the altered behavioural repertoire of the megalopa, it seems necessary to ask in which respect synaptic rearrangement might characterize development of the central nervous system.

  17. Larval feeding behavior of the truncatus group of Thrypticus (Diptera:Dolichopodidae) that breed in the aerenchyma of Pontederiaceae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Larval feeding behavior of the truncatus group of Thrypticus (Diptera: Dolichopodidae) that breed in Pontederiaceae species are presented. The larvae of T. circularis Bickel & Hernández develop in globous petioles of Eichhornia crassipes (Martius) Solms- Laubach (Pontederiaceae), digging a mine near...

  18. Larval Population Density Alters Adult Sleep in Wild-Type Drosophila melanogaster but Not in Amnesiac Mutant Flies

    PubMed Central

    Chi, Michael W.; Griffith, Leslie C.; Vecsey, Christopher G.

    2014-01-01

    Sleep has many important biological functions, but how sleep is regulated remains poorly understood. In humans, social isolation and other stressors early in life can disrupt adult sleep. In fruit flies housed at different population densities during early adulthood, social enrichment was shown to increase subsequent sleep, but it is unknown if population density during early development can also influence adult sleep. To answer this question, we maintained Drosophila larvae at a range of population densities throughout larval development, kept them isolated during early adulthood, and then tested their sleep patterns. Our findings reveal that flies that had been isolated as larvae had more fragmented sleep than those that had been raised at higher population densities. This effect was more prominent in females than in males. Larval population density did not affect sleep in female flies that were mutant for amnesiac, which has been shown to be required for normal memory consolidation, adult sleep regulation, and brain development. In contrast, larval population density effects on sleep persisted in female flies lacking the olfactory receptor or83b, suggesting that olfactory signals are not required for the effects of larval population density on adult sleep. These findings show that population density during early development can alter sleep behavior in adulthood, suggesting that genetic and/or structural changes are induced by this developmental manipulation that persist through metamorphosis. PMID:25116571

  19. Exploring the larval transcriptome of the common sole (Solea solea L.)

    PubMed Central

    2013-01-01

    Background The common sole (Solea solea) is a promising candidate for European aquaculture; however, the limited knowledge of the physiological mechanisms underlying larval development in this species has hampered the establishment of successful flatfish aquaculture. Although the fact that genomic tools and resources are available for some flatfish species, common sole genomics remains a mostly unexplored field. Here, we report, for the first time, the sequencing and characterisation of the transcriptome of S. solea and its application for the study of molecular mechanisms underlying physiological and morphological changes during larval-to-juvenile transition. Results The S. solea transcriptome was generated from whole larvae and adult tissues using the Roche 454 platform. The assembly process produced a set of 22,223 Isotigs with an average size of 726 nt, 29 contigs and a total of 203,692 singletons. Of the assembled sequences, 75.2% were annotated with at least one known transcript/protein; these transcripts were then used to develop a custom oligo-DNA microarray. A total of 14,674 oligonucleotide probes (60 nt), representing 12,836 transcripts, were in situ synthesised onto the array using Agilent non-contact ink-jet technology. The microarray platform was used to investigate the gene expression profiles of sole larvae from hatching to the juvenile form. Genes involved in the ontogenesis of the visual system are up-regulated during the early stages of larval development, while muscle development and anaerobic energy pathways increase in expression over time. The gene expression profiles of key transcripts of the thyroid hormones (TH) cascade and the temporal regulation of the GH/IGF1 (growth hormone/insulin-like growth factor I) system suggest a pivotal role of these pathways in fish growth and initiation of metamorphosis. Pre-metamorphic larvae display a distinctive transcriptomic landscape compared to previous and later stages. Our findings highlighted the up

  20. Effect of Moringa oleifera flower extract on larval trypsin and acetylcholinesterase activities in Aedes aegypti.

    PubMed

    Pontual, Emmanuel Viana; Napoleão, Thiago Henrique; Dias de Assis, Caio Rodrigo; de Souza Bezerra, Ranilson; Xavier, Haroudo Satiro; Navarro, Daniela Maria do Amaral Ferraz; Coelho, Luana Cassandra Breitenbach Barroso; Paiva, Patrícia Maria Guedes

    2012-03-01

    Aedes aegypti control is crucial to reducing dengue fever. Aedes aegypti larvae have developed resistance to organophosporous insecticides and the use of natural larvicides may help manage larval resistance by increasing elements in insecticide rotation programs. Here, we report on larvicidal activity of Moringa oleifera flower extract against A. aegypti L(1), L(2), L(3), and L(4) as well as the effect of flower extract on gut trypsin and whole-larval acetylcholinesterase from L(4.) In addition, the heated flower extract was investigated for larvicidal activity against L(4) and effect on larval gut trypsin. Moringa oleifera flower extract contains a proteinaceous trypsin inhibitor (M. oleifera flower trypsin inhibitor, MoFTI), triterpene (β-amyrin), sterol (β-sitosterol) as well as flavonoids (kaempferol and quercetin). Larvicidal activity was detected against L(2), L(3), and L(4) (LC(50) of 1.72%, 1.67%, and 0.92%, respectively). Flower extract inhibited L(4) gut trypsin (MoFTI K(i) = 0.6 nM) and did not affect acetylcholinesterase activity. In vivo assay showed that gut trypsin activity from L(4) treated with M. oleifera flower extract decreased over time (0-1,440 min) and was strongly inhibited (98.6%) after 310 min incubation; acetylcholinesterase activity was not affected. Thermal treatment resulted in a loss of trypsin inhibitor and larvicidal activities, supporting the hypothesis that flower extract contains a proteinaceous trypsin inhibitor that may be responsible for the deleterious effects on larval mortality. PMID:22392801

  1. Microscopic identification of novel cell types in the integument of larval lake sturgeon, Acipenser fulvescens.

    PubMed

    Shute, Lauren; Huebner, Erwin; Anderson, W Gary

    2016-01-01

    Osmoregulation, respiration, nutrient/mineral transport, and defense mechanisms are all evident in the integument of fish. The role of the integument in these physiological processes is particularly important during early life history in larval fishes, as functional systems such as the gills and gastrointestinal tract are not fully developed. Using a variety of microscopy techniques, we describe the morphology of keratinocytes, mitochondria rich cells, ciliated cells and mucous cells of the skin, yolk sac, and gills. The cytology we observed was similar to previous studies describing the integument of larval fish, however, we have also identified two novel cell types on the integument of larval Lake Sturgeon, Acipenser fulvescens, between 9 and 34 days post fertilization. Our detailed analysis included a multifaceted microscopy approach using scanning electron, transmission electron, and light microscopy to elucidate the histology of the tissue and cellular morphology in addition to quantification and distribution of these novel cell types. The first cell type had a characteristic ampullary shape with a central cavity and a pore opening at the surface. The second, located on the free surface of the epidermis, had an uneven plasma membrane surface. Based on the abundance of secretory vesicles, organelles necessary for protein synthesis, and the lack of neural connection in both cell types, we propose these cells to be involved in the release of semiochemicals that may act as a pheromone, alarm substance, or chemical defense mechanism. PMID:26440535

  2. Flexible responses to visual and olfactory stimuli by foraging Manduca sexta: larval nutrition affects adult behaviour

    PubMed Central

    Goyret, Joaquín; Kelber, Almut; Pfaff, Michael; Raguso, Robert A.

    2009-01-01

    Here, we show that the consequences of deficient micronutrient (β-carotene) intake during larval stages of Manduca sexta are carried across metamorphosis, affecting adult behaviour. Our manipulation of larval diet allowed us to examine how developmental plasticity impacts the interplay between visual and olfactory inputs on adult foraging behaviour. Larvae of M. sexta were reared on natural (Nicotiana tabacum) and artificial laboratory diets containing different concentrations of β-carotene (standard diet, low β-carotene, high β-carotene and cornmeal). This vitamin-A precursor has been shown to be crucial for photoreception sensitivity in the retina of M. sexta. After completing development, post-metamorphosis, starved adults were presented with artificial feeders that could be either scented or unscented. Regardless of their larval diet, adult moths fed with relatively high probabilities on scented feeders. When feeders were unscented, moths reared on tobacco were more responsive than moths reared on β-carotene-deficient artificial diets. Strikingly, moths reared on artificial diets supplemented with increasing amounts of β-carotene (low β and high β) showed increasing probabilities of response to scentless feeders. We discuss these results in relationship to the use of complex, multi-modal sensory information by foraging animals. PMID:19419987

  3. Modeling the spawning strategies and larval survival of the Brazilian sardine (Sardinella brasiliensis)

    NASA Astrophysics Data System (ADS)

    Dias, Daniela Faggiani; Pezzi, Luciano Ponzi; Gherardi, Douglas Francisco Marcolino; Camargo, Ricardo

    2014-04-01

    An Individual Based Model (IBM), coupled with a hydrodynamic model (ROMS), was used to investigate the spawning strategies and larval survival of the Brazilian Sardine in the South Brazil Bight (SBB). ROMS solutions were compared with satellite and field data to assess their representation of the physical environment. Two spawning experiments were performed for the summer along six years, coincident with ichthyoplankton survey cruises. In the first one, eggs were released in spawning habitats inferred from a spatial model. The second experiment simulated a random spawning to test the null hypothesis that there are no preferred spawning sites. Releasing eggs in the predefined spawning habitats increases larval survival, suggesting that the central-southern part of the SBB is more suitable for larvae development because of its thermodynamic characteristics. The Brazilian sardine is also capable of exploring suitable areas for spawning, according to the interannual variability of the SBB. The influence of water temperature, the presence of Cape Frio upwelling, and surface circulation on the spawning process was tested. The Cape Frio upwelling plays an important role in the modulation of Brazilian sardine spawning zones over SBB because of its lower than average water temperature. This has a direct influence on larval survival and on the interannual variability of the Brazilian sardine spawning process. The hydrodynamic condition is crucial in determining the central-southern part of SBB as the most suitable place for spawning because it enhances simulated coastal retention of larvae.

  4. Sole larval supply to coastal nurseries: Interannual variability and connectivity at interregional and interpopulation scales

    NASA Astrophysics Data System (ADS)

    Savina, M.; Lunghi, M.; Archambault, B.; Baulier, L.; Huret, M.; Le Pape, O.

    2016-05-01

    Simulating fish larval drift helps assess the sensitivity of recruitment variability to early life history. An individual-based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the meta-population scale (4 assessed stocks), from the southern North Sea to the Bay of Biscay (Western Europe) on a 26-yr time series, from 1982 to 2007. The IBM allowed each particle released to be transported by currents, to grow depending on temperature, to migrate vertically depending on development stage, to die along pelagic stages or to settle on a nursery, representing the life history from spawning to metamorphosis. The model outputs were analysed to explore interannual patterns in the amounts of settled sole larvae at the population scale; they suggested: (i) a low connectivity between populations at the larval stage, (ii) a moderate influence of interannual variation in the spawning biomass, (iii) dramatic consequences of life history on the abundance of settling larvae and (iv) the effects of climate variability on the interannual variability of the larvae settlement success.

  5. Strengthened currents override the effect of warming on lobster larval dispersal and survival.

    PubMed

    Cetina-Heredia, Paulina; Roughan, Moninya; van Sebille, Erik; Feng, Ming; Coleman, Melinda A

    2015-12-01

    Human-induced climate change is projected to increase ocean temperature and modify circulation patterns, with potential widespread implications for the transport and survival of planktonic larvae of marine organisms. Circulation affects the dispersal of larvae, whereas temperature impacts larval development and survival. However, the combined effect of changes in circulation and temperature on larval dispersal and survival has rarely been studied in a future climate scenario. Such understanding is crucial to predict future species distributions, anticipate ecosystem shifts and design effective management strategies. We simulate contemporary (1990s) and future (2060s) dispersal of lobster larvae using an eddy-resolving ocean model in south-eastern Australia, a region of rapid ocean warming. Here we show that the effects of changes in circulation and temperature can counter each other: ocean warming favours the survival of lobster larvae, whereas a strengthened western boundary current diminishes the supply of larvae to the coast by restricting cross-current larval dispersal. Furthermore, we find that changes in circulation have a stronger effect on connectivity patterns of lobster larvae along south-eastern Australia than ocean warming in the future climate so that the supply of larvae to the coast reduces by ~4% and the settlement peak shifts poleward by ~270 km in the model simulation. Thus, ocean circulation may be one of the dominant factors contributing to climate-induced changes of species ranges. PMID:26268457

  6. Methoprene-tolerant 1 regulates gene transcription to maintain insect larval status.

    PubMed

    Zhao, Wen-Li; Liu, Chun-Yan; Liu, Wen; Wang, Di; Wang, Jin-Xing; Zhao, Xiao-Fan

    2014-08-01

    Insect molting and metamorphosis are regulated by two hormones: 20-hydroxyecdysone (20E) and juvenile hormone (JH). The hormone 20E regulates gene transcription via the nuclear receptor EcR to promote metamorphosis, whereas JH regulates gene transcription via its intracellular receptor methoprene-tolerant (Met) to prevent larval-pupal transition. However, the function and mechanism of Met in various insect developments are not well understood. We propose that Met1 plays a key role in maintaining larval status not only by promoting JH-responsive gene transcription but also by repressing 20E-responsive gene transcription in the Lepidopteran insect Helicoverpa armigera. Met1 protein is increased during feeding stage and decreased during molting and metamorphic stages. Met1 is upregulated by JH III and a low concentration of 20E independently, but is downregulated by a high concentration of 20E. Knockdown of Met1 in larvae causes precocious pupation, decrease in JH pathway gene expression, and increase in 20E pathway gene expression. Met1 interacts with heat shock protein 90 and binds to JH response element to regulate Krüppel homolog 1 transcription in JH III induction. Met1 interacts with ultraspiracle protein 1 (USP1) to repress 20E transcription complex EcRB1/USP1 formation and binding to ecdysone response element. These data indicate that JH via Met1 regulates JH pathway gene expression and represses 20E pathway gene expression to maintain the larval status. PMID:24872508

  7. Not my "type": larval dispersal dimorphisms and bet-hedging in opisthobranch life histories.

    PubMed

    Krug, Patrick J

    2009-06-01

    When conditions fluctuate unpredictably, selection may favor bet-hedging strategies that vary offspring characteristics to avoid reproductive wipe-outs in bad seasons. For many marine gastropods, the dispersal potential of offspring reflects both maternal effects (egg size, egg mass properties) and larval traits (development rate, habitat choice). I present data for eight sea slugs in the genus Elysia (Opisthobranchia: Sacoglossa), highlighting potentially adaptive variation in traits like offspring size, timing of metamorphosis, hatching behavior, and settlement response. Elysia zuleicae produced both planktotrophic and lecithotrophic larvae, a true case of poecilogony. Both intracapsular and post-hatching metamorphosis occurred among clutches of "Boselia" marcusi, E. cornigera, and E. crispata, a dispersal dimorphism often misinterpreted as poecilogony. Egg masses of E. tuca hatched for up to 16 days but larvae settled only on the adult host alga Halimeda, whereas most larvae of E. papillosa spontaneously metamorphosed 5-7 days after hatching. Investment in extra-capsular yolk may allow mothers to increase larval size relative to egg size and vary offspring size within and among clutches. Flexible strategies of larval dispersal and offspring provisioning in Elysia spp. may represent adaptations to the patchy habitat of these specialized herbivores, highlighting the evolutionary importance of variation in a range of life-history traits. PMID:19556600

  8. Toxicity of organophosphorus pesticide sumithion on larval stages of stinging catfish Heteropneustes fossilis

    NASA Astrophysics Data System (ADS)

    Shahjahan, Md.; Kabir, Md. Farajul; Sumon, Kizar Ahmed; Bhowmik, Lipi Rani; Rashid, Harunur

    2016-04-01

    Sumithion is widely used to control brittle in paddy fields and tiger bug in fish larval rearing ponds. The objective of this study was to elucidate the toxic effects of sumithion on larval stages of stinging catfish Heteropneustes fossilis. Larvae were exposed to two concentrations (150 and 250 μg/L) of sumithion with one control in three replicates of each. Larvae samples were collected at 20- and 24-h intervals followed by observation under a digital microscope. Exposures of stinging catfish larvae to sumithion produced deformities including irregular head shape, lordosis, yolk sac edema, body arcuation, tissue ulceration, etc. The mortality rates of larvae were significantly increased in response to increase in sumithion concentrations. Furthermore, around 30% of the total adult stinging catfish reared in sumithiontreated aquaculture ponds were found to be deformed permanently. These findings highlight that exposure of stinging catfish to sumithion at the critical and sensitive stages in their life cycle may significantly reduce the number of returning adults. Therefore, the use of sumithion for crop protection needs to be considered carefully and alternatives to sumithion should to be developed for controlling aquatic insects in aqua-ponds during larval rearing.

  9. Structural homology of identified motoneurones in larval and adult stages of hemi- and holometabolous insects.

    PubMed

    Breidbach, O; Kutsch, W

    1990-07-15

    The set of neurones innervating the dorsal longitudinal muscles was studied with cobalt and nickel backfills in: (1) larval and adult locusts (Schistocerca gregaria and Locusta migratoria), (2) the larval and adult beetle (Zophobas morio), and (3) various segments of these insect species. In all specimens 11 neurones were encountered, which can be subdivided into a group of 7 motoneurones that stem from the next anterior ganglion and 4 neurones located in the ganglion of the segment containing the muscles. The latter group comprises 2 contralateral and 2 medial somata, of which one is a dorsal unpaired median neurone. The results were analysed under different aspects. This neural set and the basic structure of the dendritic fields is similar in: (1) different segments (serial homology), (2) the larval stage and imago of the same species with or without a pronounced metamorphosis (ontogeny), and (3) the studied hemi- and holometabolous insects (phylogeny). Our results support the notion that the structure of these neurones is conserved irrespectively of changes in the periphery and strategy of postembryonic development. PMID:2398139

  10. Cannibalistic feeding of larval Trichogramma carverae parasitoids in moth eggs

    NASA Astrophysics Data System (ADS)

    Heslin, Leeane M.; Merritt, David J.

    2005-09-01

    Wasps of the genus Trichogramma parasitise the eggs of Lepidoptera. They may deposit one or many eggs in each host. Survival is high at low density but reaches a plateau as density increases. To reveal the mechanism by which excess larvae die we chose a lepidopteran host that has flattened, transparent eggs and used video microscopy to record novel feeding behaviours and interactions of larval Trichogramma carverae (Oatman and Pinto) at different densities. Single larvae show a rapid food ingestion phase, followed by a period of extensive saliva release. Ultimately the host egg is completely consumed. The larva then extracts excess moisture from the egg, providing a dry environment for pupation. When multiple larvae are present, the initial scramble for food results in the larvae consuming all of the egg contents early in development. All larvae survive if there is sufficient food for all to reach a threshold developmental stage. If not, physical proximity results in attack and consumption of others, continuing until the surviving larvae reach the threshold stage beyond which attacks seem to be no longer effective. The number of larvae remaining at the end of rapid ingestion dictates how many will survive to emerge as adults.

  11. Effects of hatching time for larval ambystomatid salamanders

    USGS Publications Warehouse

    Boone, M.D.; Scott, D.E.; Niewiarowski, P.H.

    2002-01-01

    In aquatic communities, the phenology of breeding may influence species interactions. In the early-breeding marbled salamander, Ambystoma opacum, timing of pond filling may determine whether interactions among larvae are competitive or predatory. The objectives of our studies were to determine how time of egg hatching affected size, larval period, and survival to metamorphosis in A. opacum, and if early-hatching in A. opacum influenced the competitive and predator-prey relationships with smaller larvae of the mole salamander, Ambystoma talpoideum. Salamander larvae were reared from hatching through metamorphosis in large, outdoor enclosures located in a natural temporary pond in Aiken County, South Carolina, in two experiments. In study 1, we reared early- and late-hatching A. opacum larvae separately from hatching through metamorphosis. In study 2, we examined how early- versus late-hatching A. opacum affected a syntopic species, A. talpoideum. In general, early-hatching A. opacum were larger and older at metamorphosis, had greater survival, and left the pond earlier than late-hatching larvae. Ambystoma talpoideum reared in the presence of early-hatching A. opacum had lower survival than in controls, suggesting that A. opacum may predate upon A. talpoideum when they gain a growth advantage over later-hatching larvae. Our studies demonstrate that time of pond filling and phenology of breeding may influence population dynamics and alter the nature of relationships that develop among species.

  12. Microarray Noninvasive Neuronal Seizure Recordings from Intact Larval Zebrafish

    PubMed Central

    Meyer, Michaela; Dhamne, Sameer C.; LaCoursiere, Christopher M.; Tambunan, Dimira; Poduri, Annapurna; Rotenberg, Alexander

    2016-01-01

    Zebrafish epilepsy models are emerging tools in experimental epilepsy. Zebrafish larvae, in particular, are advantageous because they can be easily genetically altered and used for developmental and drug studies since agents applied to the bath penetrate the organism easily. Methods for electrophysiological recordings in zebrafish are new and evolving. We present a novel multi-electrode array method to non-invasively record electrical activity from up to 61 locations of an intact larval zebrafish head. This method enables transcranial noninvasive recording of extracellular field potentials (which include multi-unit activity and EEG) to identify epileptic seizures. To record from the brains of zebrafish larvae, the dorsum of the head of an intact larva was secured onto a multi-electrode array. We recorded from individual electrodes for at least three hours and quantified neuronal firing frequency, spike patterns (continuous or bursting), and synchrony of neuronal firing. Following 15 mM potassium chloride- or pentylenetetrazole-infusion into the bath, spike and burst rate increased significantly. Additionally, synchrony of neuronal firing across channels, a hallmark of epileptic seizures, also increased. Notably, the fish survived the experiment. This non-invasive method complements present invasive zebrafish neurophysiological techniques: it affords the advantages of high spatial and temporal resolution, a capacity to measure multiregional activity and neuronal synchrony in seizures, and fish survival for future experiments, such as studies of epileptogenesis and development. PMID:27281339

  13. Cannibalistic feeding of larval Trichogramma carverae parasitoids in moth eggs.

    PubMed

    Heslin, Leeane M; Merritt, David J

    2005-09-01

    Wasps of the genus Trichogramma parasitise the eggs of Lepidoptera. They may deposit one or many eggs in each host. Survival is high at low density but reaches a plateau as density increases. To reveal the mechanism by which excess larvae die we chose a lepidopteran host that has flattened, transparent eggs and used video microscopy to record novel feeding behaviours and interactions of larval Trichogramma carverae (Oatman and Pinto) at different densities. Single larvae show a rapid food ingestion phase, followed by a period of extensive saliva release. Ultimately the host egg is completely consumed. The larva then extracts excess moisture from the egg, providing a dry environment for pupation. When multiple larvae are present, the initial scramble for food results in the larvae consuming all of the egg contents early in development. All larvae survive if there is sufficient food for all to reach a threshold developmental stage. If not, physical proximity results in attack and consumption of others, continuing until the surviving larvae reach the threshold stage beyond which attacks seem to be no longer effective. The number of larvae remaining at the end of rapid ingestion dictates how many will survive to emerge as adults. PMID:16133105

  14. Optogenetic elevation of endogenous glucocorticoid level in larval zebrafish

    PubMed Central

    De Marco, Rodrigo J.; Groneberg, Antonia H.; Yeh, Chen-Min; Castillo Ramírez, Luis A.; Ryu, Soojin

    2013-01-01

    The stress response is a suite of physiological and behavioral processes that help to maintain or reestablish homeostasis. Central to the stress response is the hypothalamic-pituitary-adrenal (HPA) axis, as it releases crucial hormones in response to stress. Glucocorticoids (GCs) are the final effector hormones of the HPA axis, and exert a variety of actions under both basal and stress conditions. Despite their far-reaching importance for health, specific GC effects have been difficult to pin-down due to a lack of methods for selectively manipulating endogenous GC levels. Hence, in order to study stress-induced GC effects, we developed a novel optogenetic approach to selectively manipulate the rise of GCs triggered by stress. Using this approach, we could induce both transient hypercortisolic states and persistent forms of hypercortisolaemia in freely behaving larval zebrafish. Our results also established that transient hypercortisolism leads to enhanced locomotion shortly after stressor exposure. Altogether, we present a highly specific method for manipulating the gain of the stress axis with high temporal accuracy, altering endocrine and behavioral responses to stress as well as basal GC levels. Our study offers a powerful tool for the analysis of rapid (non-genomic) and delayed (genomic) GC effects on brain function and behavior, feedbacks within the stress axis and developmental programming by GCs. PMID:23653595

  15. Transmembrane channel-like (tmc) gene regulates Drosophila larval locomotion.

    PubMed

    Guo, Yanmeng; Wang, Yuping; Zhang, Wei; Meltzer, Shan; Zanini, Damiano; Yu, Yue; Li, Jiefu; Cheng, Tong; Guo, Zhenhao; Wang, Qingxiu; Jacobs, Julie S; Sharma, Yashoda; Eberl, Daniel F; Göpfert, Martin C; Jan, Lily Yeh; Jan, Yuh Nung; Wang, Zuoren

    2016-06-28

    Drosophila larval locomotion, which entails rhythmic body contractions, is controlled by sensory feedback from proprioceptors. The molecular mechanisms mediating this feedback are little understood. By using genetic knock-in and immunostaining, we found that the Drosophila melanogaster transmembrane channel-like (tmc) gene is expressed in the larval class I and class II dendritic arborization (da) neurons and bipolar dendrite (bd) neurons, both of which are known to provide sensory feedback for larval locomotion. Larvae with knockdown or loss of tmc function displayed reduced crawling speeds, increased head cast frequencies, and enhanced backward locomotion. Expressing Drosophila TMC or mammalian TMC1 and/or TMC2 in the tmc-positive neurons rescued these mutant phenotypes. Bending of the larval body activated the tmc-positive neurons, and in tmc mutants this bending response was impaired. This implicates TMC's roles in Drosophila proprioception and the sensory control of larval locomotion. It also provides evidence for a functional conservation between Drosophila and mammalian TMCs. PMID:27298354

  16. Evolution of insect metamorphosis: a microarray-based study of larval and adult gene expression in the ant Camponotus festinatus.

    PubMed

    Goodisman, Michael A D; Isoe, Jun; Wheeler, Diana E; Wells, Michael A

    2005-04-01

    Holometabolous insects inhabit almost every terrestrial ecosystem. The evolutionary success of holometabolous insects stems partly from their developmental program, which includes discrete larval and adult stages. To gain an understanding of how development differs among holometabolous insect taxa, we used cDNA microarray technology to examine differences in gene expression between larval and adult Camponotus festinatus ants. We then compared expression patterns obtained from our study to those observed in the fruitfly Drosophila melanogaster. We found that many genes showed distinct patterns of expression between the larval and adult ant life stages, a result that was confirmed through quantitative reverse-transcriptase polymerase chain reaction. Genes involved in protein metabolism and possessing structural activity tended to be more highly expressed in larval than adult ants. In contrast, genes relatively upregulated in adults possessed a greater diversity of functions and activities. We also discovered that patterns of expression observed for homologous genes in D. melanogaster differed substantially from those observed in C. festinatus. Our results suggest that the specific molecular mechanisms involved in metamorphosis will differ substantially between insect taxa. Systematic investigation of gene expression during development of other taxa will provide additional information on how developmental pathways evolve. PMID:15926695

  17. THE EFFECTS ON LARVAL DEVELOPMENT AND MORTALITY, PUPATION AND TOLERANCE TO TOXIC PROTEIN IN COTTON BOLLS, POLLEN, AND ARTIFICIAL DIET BIOASSAYS OF PINK BOLLWORM (PBW) FEEDING ON NUCOTN 33B COTTON BOLLS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cottons that have a gene or genes from Bacillus thuringiensis Kurstaki (Berliner) that produce insect toxins have been grown in Arizona since 1996. The threat of pink bollworm (PBW), Pectinophora gossypiella (Saunders) resistance development to the toxin has been of continuing concern. The increasin...

  18. Measurement of Larval Activity in the Drosophila Activity Monitor

    PubMed Central

    McParland, Aidan L.; Follansbee, Taylor L.; Ganter, Geoffrey K.

    2016-01-01

    Drosophila larvae are used in many behavioral studies, yet a simple device for measuring basic parameters of larval activity has not been available. This protocol repurposes an instrument often used to measure adult activity, the TriKinetics Drosophila activity monitor (MB5 Multi-Beam Activity Monitor) to study larval activity. The instrument can monitor the movements of animals in 16 individual 8 cm glass assay tubes, using 17 infrared detection beams per tube. Logging software automatically saves data to a computer, recording parameters such as number of moves, times sensors were triggered, and animals’ positions within the tubes. The data can then be analyzed to represent overall locomotion and/or position preference as well as other measurements. All data are easily accessible and compatible with basic graphing and data manipulation software. This protocol will discuss how to use the apparatus, how to operate the software and how to run a larval activity assay from start to finish. PMID:25993121

  19. Effects of beach morphology and waves on onshore larval transport

    NASA Astrophysics Data System (ADS)

    Fujimura, A.; Reniers, A.; Paris, C. B.; Shanks, A.; MacMahan, J.; Morgan, S.

    2015-12-01

    Larvae of intertidal species grow offshore, and migrate back to the shore when they are ready to settle on their adult substrates. In order to reach the habitat, they must cross the surf zone, which is characterized as a semi-permeable barrier. This is accomplished through physical forcing (i.e., waves and current) as well as their own behavior. Two possible scenarios of onshore larval transport are proposed: Negatively buoyant larvae stay in the bottom boundary layer because of turbulence-dependent sinking behavior, and are carried toward the shore by streaming of the bottom boundary layer; positively buoyant larvae move to the shore during onshore wind events, and sink to the bottom once they encounter high turbulence (i.e., surf zone edge), where they are carried by the bottom current toward the shore (Fujimura et al. 2014). Our biophysical Lagrangian particle tracking model helps to explain how beach morphology and wave conditions affect larval distribution patterns and abundance. Model results and field observations show that larval abundance in the surf zone is higher at mildly sloped, rip-channeled beaches than at steep pocket beaches. Beach attributes are broken up to examine which and how beach configuration factors affect larval abundance. Modeling with alongshore uniform beaches with variable slopes reveal that larval populations in the surf zone are negatively correlated with beach steepness. Alongshore variability enhances onshore larval transport because of increased cross-shore water exchange by rip currents. Wave groups produce transient rip currents and enhance cross-shore exchange. Effects of other wave components, such as wave height and breaking wave rollers are also considered.

  20. Effects of coastal transport on larval patches: Models and observations

    NASA Astrophysics Data System (ADS)

    Tilburg, Charles E.; Houser, Letise T.; Steppe, Cecily N.; Garvine, Richard W.; Epifanio, Charles E.

    2006-03-01

    We used a combination of field observations and numerical modeling to examine the physical mechanisms responsible for the evolution and transport of patches of blue crab larvae in the mouth of Delaware Bay. The observations consisted of larval collections and surface salinity measurements taken along a moving spatial grid whose origin was determined by a satellite-tracked drifter. Examination of field observations revealed a slender larval patch that was aligned with salinity contours. Measurement of the salting rate of the larval patch indicated that the patch moved through the offshore edge of a buoyant plume due to wind-driven upwelling circulation. A numerical model that provided realistic simulations of the flow field at the mouth of Delaware Bay and the adjoining coastal ocean was used to examine the physical mechanisms responsible for the movement and evolution of the patch. We conducted a series of simulations in which we separately examined the effects of tides, buoyancy-driven flow, and wind-driven transport. Results showed that both tides and buoyancy-driven flow tend to elongate an initially square fluid element. Although winds alone have little effect on the shape of a patch, wind-driven flow can effectively move a patch through a complex flow field in which the deformation by tides and buoyancy-driven circulation can have significant effects. This study represents the first observation and analysis of a larval patch that remains intact while moving through the edge of a buoyant plume. It provides new insight into the shape of larval patches in Delaware Bay and any region with strong buoyancy- and tidally-driven flow, suggesting that typical larval patches may not be characterized by equal across- and alongshelf dimensions but instead tend to be slender shapes that are aligned with the flow field.

  1. Larval nematodes found in amphibians from northeastern Argentina.

    PubMed

    González, C E; Hamann, M I

    2010-11-01

    Five species of amphibians, Leptodactylus podicipinus, Scinax acuminatus, S. nasicus, Rhinella fernandezae and Pseudis paradoxa, were collected in Corrientes province, Argentina and searched for larval nematodes. All larval nematodes were found as cysts in the serous of the stomach of hosts. Were identified one superfamily, Seuratoidea; one genus, Spiroxys (Superfamily Gnathostomatoidea) and one family, Rhabdochonidae (Superfamily Thelazioidea). We present a description and illustrations of these taxa. These nematodes have an indirect life cycle and amphibians are infected by consuming invertebrate, the intermediate hosts. The genus Spiroxys and superfamily Seuratoidea were reported for the first time for Argentinean amphibians. PMID:21180919

  2. A merganser die-off associated with larval eustrongylides

    USGS Publications Warehouse

    Locke, L.N.; DeWitt, J.B.; Menzie, C.M.; Kerwin, J.A.

    1964-01-01

    A die-off of red-breasted mergansers on Lake Holly, Virginia Beach, Virginia, was found to be due to a larval Eustrongylides. Massive tissue destruction and hemorrhage was produced by the migration of the larval Eustrongylides. Earlier stages of the same Eustrongylides were found in eastern mosquitofish and silversides upon which the mergansers had been feeding. In addition, residues of DDT were found in mosquitofish, gizzard shad, and five mergansers collected from Lake Holly, and in the tissues of two mergansers from Back Bay, Virginia. However, the information available was insufficient to establish the significance of these residue levels.

  3. Shedding light on the larval genus Eretmocaris: morphological larval features of two closely related trans-isthmian Lysmata species (Decapoda: Caridea: Hippolytidae) described on the basis of laboratory cultured material

    NASA Astrophysics Data System (ADS)

    Bartilotti, Cátia; Calado, Ricardo; Rhyne, Andrew; Dos Santos, Antonina

    2012-03-01

    Complete larval series are known for only three of the 39 valid species worldwide in the genus Lysmata. The present work deals with the larval development of two closely related trans-isthmian species of Lysmata, L. galapagensis (eastern Pacific Ocean), and L. moorei (southwestern Atlantic Ocean), using laboratory cultured material. The morphological features of the first four zoeal stages of both species, the fifth to seventh stages of L. galapagensis, and the last stage of L. moorei are described and compared with the larval descriptions currently available for the genus . Larvae of both species hatch with a similar form to L. seticaudata, with their first and fifth pereiopods as buds, and show a very steady development of their morphological characters. The zoeal characters match the phylogenetic results currently available for the genus Lysmata and L. galapagensis, L. moorei and L. seticaudata belong to the same monophyletic clade. We hypothesize that the larvae of all species within this clade will hatch with the first and fifth pereiopods as buds and will present a maximum of nine zoeal stages. The relationships between the studied material and the composite larval genus Eretmocaris are discussed, with emphasis on Eretmocaris corniger which has an extremely long rostrum and a spine on the dorsal surface of the third pleomere, characters also recorded in L. galapagensis. The larval forms earlier described as the tropical eastern Pacific E. corniger are matched to a known Lysmata species, L. galapagensis. The identity of E. corniger larvae recorded one century ago from the tropical eastern Atlantic is also discussed.

  4. Relationships between habitat conditions, larval traits, and juvenile performance in a marine invertebrate.

    PubMed

    Giménez, Luis

    2010-05-01

    Environmental effects on sets of traits of organisms can have important consequences on populations. In marine species with complex life cycles, plastic responses in larval traits can affect size at metamorphosis and juvenile growth. These traits can ultimately affect survival and recruitment. Here, I evaluate links between pelagic conditions, natural variations in larval physiological traits (duration of development, size of the megalopa stage), size at metamorphosis, and juvenile growth in the shore crab Carcinus maenas. I sampled settling larvae (megalopae) of C. maenas, daily, during the settlement season of three consecutive years, in the island of Helgoland (North Sea, German Bight). Megalopae were brought to the laboratory where postmetamorphic growth was evaluated under different larval food environments. Traits varied considerably at several temporal scales; variation was not consistent among years. However, the size at metamorphosis was always larger at the start of the settlement season. Some variability correlated with predicted changes in transport processes and dynamics of plume fronts around the study area. Positive relationships between predicted periods of formation of plume fronts, settlement rates, and size at metamorphosis suggest a link between oceanographic conditions and individual traits. Size at metamorphosis explained juvenile growth rates: during the first five juvenile stages, larger individuals grew faster and reached larger size at stage (that is, at any stage observed). Megalopae experiencing ad libitum food conditions grew faster as juveniles than those deprived of food, showing that size at metamorphosis and juvenile growth respond plastically to variations in the larval food environment. I conclude that juvenile growth rate in C. maenas can be affected by natural environmental conditions experienced by larval stages; this effect is mediated by changes in the size at metamorphosis. Most likely the most important factor operating on

  5. BOLTS: a BiOphysical Larval Tracking System for Measuring Dispersal Characteristics and Marine Population Connectivity

    NASA Astrophysics Data System (ADS)

    Paris, C. B.; Srinivasan, A.; Kourafalou, V.; Sponaugle, S.; Cowen, R. K.

    2008-12-01

    While metapopulation research with hypothetical dispersal matrices has shown how the scales of larval dispersal, transport processes, local recruitment, and temporal and spatial variability in dispersal influence population persistence, the pattern of demographic connectivity produced by larval dispersal is still a key uncertainty. To address this problem, a coupled bio-physical model has been developed that quantifies the degree of connectivity between populations. Such spatially explicit models, forced by dynamic currents coupled to a realistic seascape and life history traits, produce dispersal kernels for a range of scales over which dispersal is practically unquantifiable by current empirical methods. The BiOphysical Larval Tracking System (BOLTS) presented here allows a Lagrangian stochastic individual-based model (IBM) to be coupled via OPENDAP framework to any 3-dimensional fields of circulation models including to domains of various resolutions through 'Lagrangian nesting'. We demonstrate the capabilities of the software in measuring the characteristics of dispersal and evaluating the variability of larval connectivity through two examples at different scales: 1) Caribbean-scale simulations of BOLTS using the large scale (resolution ~7 km) Hybrid Coordinate Ocean Model (HYCOM) from the Global Data Assimilative Experiment (GODAE) provide us with expected connectivity patterns of a reef building coral. By seeding the model with a large number of active particles, it is possible to assemble dispersal kernels and migration matrices from the start (spawning) and the end point (settlement) of individual particle trajectories. Any single run is a stochastic realization of a probabilistic process, thus the full probability density function (pdf) of the kernel requires averaging over many dispersal events. The model output is further corroborated with empirical measures of gene flow among coral colonies around the Caribbean. 2) Coastal-scale simulations of BOLTS

  6. Effect of maize lines on larval fitness costs of Cry1F resistance in the European corn borer (Lepidoptera: Crambidae).

    PubMed

    Petzold-Maxwell, Jennifer L; Siegfried, Blair D; Hellmich, Richard L; Abel, Craig A; Coates, Brad S; Spencer, Terrence A; Gassmann, Aaron J

    2014-04-01

    Crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted and enable management of key insect pests while reducing the use of conventional insecticides. However, the evolution of Bt resistance could diminish these benefits. Fitness costs of Bt resistance occur in the absence of Bt toxin when individuals with resistance alleles show a reduction in fitness relative to susceptible individuals, and they can delay the evolution of resistance. Ecological factors including host-plant variety can affect the magnitude of fitness costs, and consequently, the degree to which fitness costs delay resistance. In this study, we measured fitness costs of resistance to Bt toxin Cry1F in the European corn borer Ostrinia nubilalis Hübner (Lepidoptera: Crambidae) using Cry1F-resistant and Cry1F-susceptible strains sharing a similar genetic background. Fitness costs were tested on three lines of maize, Zea mays L., by measuring larval survival and development in two greenhouse experiments with plants in either the vegetative or reproductive stage. Both experiments showed that maize line significantly affected larval survival and developmental rate. However, larval survival, mass, and developmental rate did not differ between the Cry1F-resistant and susceptible strains, indicating a lack of fitness costs of resistance to Cry1F for the larval fitness components measured in this experiment. Future experiments should test for fitness costs of Cry1F resistance affecting survival to adulthood and adult life-history parameters. PMID:24772559

  7. Insulin- and warts-dependent regulation of tracheal plasticity modulates systemic larval growth during hypoxia in Drosophila melanogaster.

    PubMed

    Wong, Daniel M; Shen, Zhouyang; Owyang, Kristin E; Martinez-Agosto, Julian A

    2014-01-01

    Adaptation to dynamic environmental cues during organismal development requires coordination of tissue growth with available resources. More specifically, the effects of oxygen availability on body size have been well-documented, but the mechanisms through which hypoxia restricts systemic growth have not been fully elucidated. Here, we characterize the larval growth and metabolic defects in Drosophila that result from hypoxia. Hypoxic conditions reduced fat body opacity and increased lipid droplet accumulation in this tissue, without eliciting lipid aggregation in hepatocyte-like cells called oenocytes. Additionally, hypoxia increased the retention of Dilp2 in the insulin-producing cells of the larval brain, associated with a reduction of insulin signaling in peripheral tissues. Overexpression of the wildtype form of the insulin receptor ubiquitously and in the larval trachea rendered larvae resistant to hypoxia-induced growth restriction. Furthermore, Warts downregulation in the trachea was similar to increased insulin receptor signaling during oxygen deprivation, which both rescued hypoxia-induced growth restriction, inhibition of tracheal molting, and developmental delay. Insulin signaling and loss of Warts function increased tracheal growth and augmented tracheal plasticity under hypoxic conditions, enhancing oxygen delivery during periods of oxygen deprivation. Our findings demonstrate a mechanism that coordinates oxygen availability with systemic growth in which hypoxia-induced reduction of insulin receptor signaling decreases plasticity of the larval trachea that is required for the maintenance of systemic growth during times of limiting oxygen availability. PMID:25541690

  8. Butterfly Larval Host Plant use in a Tropical Urban Context: Life History Associations, Herbivory, and Landscape Factors

    PubMed Central

    Tiple, Ashish D.; Khurad, Arun M.; Dennis, Roger L. H.

    2011-01-01

    This study examines butterfly larval host plants, herbivory and related life history attributes within Nagpur City, India. The larval host plants of 120 butterfly species are identified and their host specificity, life form, biotope, abundance and perennation recorded; of the 126 larval host plants, most are trees (49), with fewer herbs (43), shrubs (22), climbers (7) and stem parasites (2). They include 89 wild, 23 cultivated, 11 wild/cultivated and 3 exotic plant species; 78 are perennials, 43 annuals and 5 biannuals. Plants belonging to Poaceae and Fabaceae are most widely used by butterfly larvae. In addition to distinctions in host plant family affiliation, a number of significant differences between butterfly families have been identified in host use patterns: for life forms, biotopes, landforms, perennation, host specificity, egg batch size and ant associations. These differences arising from the development of a butterfly resource database have important implications for conserving butterfly species within the city area. Differences in overall butterfly population sizes within the city relate mainly to the number of host plants used, but other influences, including egg batch size and host specificity are identified. Much of the variation in population size is unaccounted for and points to the need to investigate larval host plant life history and strategies as population size is not simply dependent on host plant abundance. PMID:21864159

  9. Butterfly larval host plant use in a tropical urban context: life history associations, herbivory, and landscape factors.

    PubMed

    Tiple, Ashish D; Khurad, Arun M; Dennis, Roger L H

    2011-01-01

    This study examines butterfly larval host plants, herbivory and related life history attributes within Nagpur City, India. The larval host plants of 120 butterfly species are identified and their host specificity, life form, biotope, abundance and perennation recorded; of the 126 larval host plants, most are trees (49), with fewer herbs (43), shrubs (22), climbers (7) and stem parasites (2). They include 89 wild, 23 cultivated, 11 wild/cultivated and 3 exotic plant species; 78 are perennials, 43 annuals and 5 biannuals. Plants belonging to Poaceae and Fabaceae are most widely used by butterfly larvae. In addition to distinctions in host plant family affiliation, a number of significant differences between butterfly families have been identified in host use patterns: for life forms, biotopes, landforms, perennation, host specificity, egg batch size and ant associations. These differences arising from the development of a butterfly resource database have important implications for conserving butterfly species within the city area. Differences in overall butterfly population sizes within the city relate mainly to the number of host plants used, but other influences, including egg batch size and host specificity are identified. Much of the variation in population size is unaccounted for and points to the need to investigate larval host plant life history and strategies as population size is not simply dependent on host plant abundance. PMID:21864159

  10. Larval growth rate is associated with the composition of the gut microbiota in the Glanville fritillary butterfly.

    PubMed

    Ruokolainen, L; Ikonen, S; Makkonen, H; Hanski, I

    2016-07-01

    The rapidly increasing body of literature on commensal microbiota has revealed a large phylotypic and functional diversity of microbes associated with vertebrates and invertebrates. In insects, the gut microbiota plays a role in digestion and metabolism of the host as well as protects the host against pathogens. In the study reported here, we sampled gut microbiota of the larvae of the Glanville fritillary butterfly (Melitaea cinxia). The larvae were collected from the field or reared in the laboratory. This butterfly has two host plant species, Plantago lanceolata and Veronica spicata, and the host plant species is known from previous studies to influence larval growth rate. However, our results demonstrate that about 50 % of the variation in larval growth rate can be attributed to the effect of the gut microbial composition plus the joint effect of microbiota and the host plant species, while host plant species alone makes no significant contribution. Our results support previous studies showing that diet influences the gut microbiota but, more unexpectedly, that the composition of the gut microbiota significantly influences larval growth rate. We suggest that host plant effects on larval growth and development observed in many previous studies may be mediated via the gut microbiota. While we measured the growth rate only in laboratory-reared larvae, the similarity of the gut microbial composition between samples from field-collected and laboratory-reared larvae suggests that the results can be generalized to natural conditions. PMID:27000942

  11. Insulin- and Warts-Dependent Regulation of Tracheal Plasticity Modulates Systemic Larval Growth during Hypoxia in Drosophila melanogaster

    PubMed Central

    Wong, Daniel M.; Shen, Zhouyang; Owyang, Kristin E.; Martinez-Agosto, Julian A.

    2014-01-01

    Adaptation to dynamic environmental cues during organismal development requires coordination of tissue growth with available resources. More specifically, the effects of oxygen availability on body size have been well-documented, but the mechanisms through which hypoxia restricts systemic growth have not been fully elucidated. Here, we characterize the larval growth and metabolic defects in Drosophila that result from hypoxia. Hypoxic conditions reduced fat body opacity and increased lipid droplet accumulation in this tissue, without eliciting lipid aggregation in hepatocyte-like cells called oenocytes. Additionally, hypoxia increased the retention of Dilp2 in the insulin-producing cells of the larval brain, associated with a reduction of insulin signaling in peripheral tissues. Overexpression of the wildtype form of the insulin receptor ubiquitously and in the larval trachea rendered larvae resistant to hypoxia-induced growth restriction. Furthermore, Warts downregulation in the trachea was similar to increased insulin receptor signaling during oxygen deprivation, which both rescued hypoxia-induced growth restriction, inhibition of tracheal molting, and developmental delay. Insulin signaling and loss of Warts function increased tracheal growth and augmented tracheal plasticity under hypoxic conditions, enhancing oxygen delivery during periods of oxygen deprivation. Our findings demonstrate a mechanism that coordinates oxygen availability with systemic growth in which hypoxia-induced reduction of insulin receptor signaling decreases plasticity of the larval trachea that is required for the maintenance of systemic growth during times of limiting oxygen availability. PMID:25541690

  12. Techniques and methods for estimating abundance of larval and metamorphosed sea lampreys in Great Lakes tributaries, 1995 to 2001

    USGS Publications Warehouse

    Slade, Jeffrey W.; Adams, Jean V.; Christie, Gavin C.; Cuddy, Douglas W.; Fodale, Michael F.; Heinrich, John W.; Quinlan, Henry R.; Weise, Jerry G.; Weisser, John W.; Young, Robert J.

    2003-01-01

    Before 1995, Great Lakes streams were selected for lampricide treatment based primarily on qualitative measures of the relative abundance of larval sea lampreys, Petromyzon marinus. New integrated pest management approaches required standardized quantitative measures of sea lamprey. This paper evaluates historical larval assessment techniques and data and describes how new standardized methods for estimating abundance of larval and metamorphosed sea lampreys were developed and implemented. These new methods have been used to estimate larval and metamorphosed sea lamprey abundance in about 100 Great Lakes streams annually and to rank them for lampricide treatment since 1995. Implementation of these methods has provided a quantitative means of selecting streams for treatment based on treatment cost and estimated production of metamorphosed sea lampreys, provided managers with a tool to estimate potential recruitment of sea lampreys to the Great Lakes and the ability to measure the potential consequences of not treating streams, resulting in a more justifiable allocation of resources. The empirical data produced can also be used to simulate the impacts of various control scenarios.

  13. The structure of mollusc larval shells formed in the presence of the chitin synthase inhibitor Nikkomycin Z

    PubMed Central

    Schönitzer, Veronika; Weiss, Ingrid M

    2007-01-01

    Background Chitin self-assembly provides a dynamic extracellular biomineralization interface. The insoluble matrix of larval shells of the marine bivalve mollusc Mytilus galloprovincialis consists of chitinous material that is distributed and structured in relation to characteristic shell features. Mollusc shell chitin is synthesized via a complex transmembrane chitin synthase with an intracellular myosin motor domain. Results Enzymatic mollusc chitin synthesis was investigated in vivo by using the small-molecule drug NikkomycinZ, a structural analogue to the sugar donor substrate UDP-N-acetyl-D-glucosamine (UDP-GlcNAc). The impact on mollusc shell formation was analyzed by binocular microscopy, polarized light video microscopy in vivo, and scanning electron microscopy data obtained from shell material formed in the presence of NikkomycinZ. The partial inhibition of chitin synthesis in vivo during larval development by NikkomycinZ (5 μM – 10 μM) dramatically alters the structure and thus the functionality of the larval shell at various growth fronts, such as the bivalve hinge and the shell's edges. Conclusion Provided that NikkomycinZ mainly affects chitin synthesis in molluscs, the presented data suggest that the mollusc chitin synthase fulfils an important enzymatic role in the coordinated formation of larval bivalve shells. It can be speculated that chitin synthesis bears the potential to contribute via signal transduction pathways to the implementation of hierarchical patterns into chitin mineral-composites such as prismatic, nacre, and crossed-lamellar shell types. PMID:17986326

  14. Seasonal variations in larval biomass and biochemical composition of brown shrimp, Crangon crangon (Decapoda, Caridea), at hatching

    NASA Astrophysics Data System (ADS)

    Urzúa, Ángel; Anger, Klaus

    2013-06-01

    The "brown shrimp", Crangon crangon (Linnaeus 1758), is a benthic key species in the North Sea ecosystem, supporting an intense commercial fishery. Its reproductive pattern is characterized by a continuous spawning season from mid-winter to early autumn. During this extended period, C. crangon shows significant seasonal variations in egg size and embryonic biomass, which may influence larval quality at hatching. In the present study, we quantified seasonal changes in dry weight (W) and chemical composition (CHN, protein and lipid) of newly hatched larvae of C. crangon. Our data revealed significant variations, with maximum biomass values at the beginning of the hatching season (February-March), a decrease throughout spring (April-May) and a minimum in summer (June-September). While all absolute values of biomass and biochemical constituents per larva showed highly significant differences between months ( P < 0.001), CHN, protein and lipid concentrations (expressed as percentage values of dry weight) showed only marginally significant differences ( P < 0.05). According to generalized additive models (GAM), key variables of embryonic development exerted significant effects on larval condition at hatching: The larval carbon content (C) was positively correlated with embryonic carbon content shortly after egg-laying ( r 2 = 0.60; P < 0.001) and negatively with the average incubation temperature during the period of embryonic development ( r 2 = 0.35; P < 0.001). Additionally, water temperature ( r 2 = 0.57; P < 0.001) and food availability (phytoplankton C; r 2 = 0.39; P < 0.001) at the time of hatching were negatively correlated with larval C content at hatching. In conclusion, "winter larvae" hatching from larger "winter eggs" showed higher initial values of biomass compared to "summer larvae" originating from smaller "summer eggs". This indicates carry-over effects persisting from the embryonic to the larval phase. Since "winter larvae" are more likely exposed to

  15. Increased Long-Flight Activity Triggered in Beet Armyworm by Larval Feeding on Diet Containing Cry1Ac Protoxin

    PubMed Central

    Jiang, Xing Fu; Chen, Jian; Zhang, Lei; Sappington, Thomas W.; Luo, Li Zhi

    2013-01-01

    Evaluating ecological safety and conducting pest risk analysis for transgenic crops are vitally important before their commercial planting. The beet armyworm, Spodoptera exigua, a long-distance migratory insect pest, is not a direct target of transgenic Cry1Ac-expressing cotton in China, but nevertheless it has recently become an important pest. Migrants leaving their natal field arrive in other appropriate habitat far away in a short time, often followed by larval outbreaks. S. exigua has low susceptibility to Cry1Ac. However, our results from laboratory experiments identified (i) sublethal effects of Cry1Ac protoxin on larval development rate, larval and pupal weight, and adult lifetime fecundity, and (ii) increased long-flight behavior triggered by Cry1Ac which may contribute to larval outbreaks elsewhere. No significant differences in larval mortality, pupation rate, adult emergence rate, longevity, pre-oviposition period, or oviposition period were observed between controls and larvae fed on artificial diet incorporating a low concentration of Cry1Ac protoxin. The negative sublethal effects on some developmental and reproductive traits and lack of effect on others suggest they do not contribute to the observed severity of S. exigua outbreaks after feeding on Cry1Ac cotton. Interestingly, the percentage of long fliers increased significantly when larvae were reared on diet containing either of two low-dose treatments of Cry1Ac, suggesting a possible increased propensity to disperse long distances triggered by Cry1Ac. We hypothesize that negative effects on development and reproduction caused by Cry1Ac in the diet are offset by increased flight propensity triggered by the poor food conditions, thereby improving the chances of escaping adverse local conditions before oviposition. Increased long-flight propensity in turn may amplify the area damaged by outbreak populations. This phenomenon might be common in other migratory insect pests receiving sublethal doses

  16. DsRNA-mediated silencing of Nudix hydrolase in Trichinella spiralis inhibits the larval invasion and survival in mice.

    PubMed

    Zhang, Shuai Bing; Jiang, Peng; Wang, Zhong Quan; Long, Shao Rong; Liu, Ruo Dan; Zhang, Xi; Yang, Wei; Ren, Hui Jun; Cui, Jing

    2016-03-01

    The aim of this study was to investigate the functions of Trichinella spiralis Nudix hydrolase (TsNd) during the larval invasion of intestinal epithelial cells (IECs), development and survival in host by RNAi. The TsNd-specific double-stranded RNA (dsRNA) was designed to silence the expression of TsNd in T. spiralis larvae. DsRNA were delivered to the larvae by soaking incubation or electroporation. Silencing effect of TsNd transcription and expression was determined by real-time PCR and Western blotting, respectively. The infectivity of larvae treated with dsRNA was investigated by the in vitro larval invasion of IECs and experimental infection in mice. After being soaked with 40 ng/μl of dsRNA-TsNd, the transcription and expression level of TsNd gene was inhibited 65.8% and 56.4%, respectively. After being electroporated with 40 ng/μl of dsRNA-TsNd, the transcription and expression level of TsNd gene was inhibited 74.2% and 58.2%, respectively. Silencing TsNd expression by both soaking and electroporation inhibited significantly the larval invasion of IECs in a dose-dependent manner (r1 = -0.96798, r2 = -0.98707). Compared with the mice inoculated with untreated larvae, mice inoculated with larvae soaked with TsNd dsRNA displayed a 49.9% reduction in adult worms and 39.9% reduction in muscle larvae, while mice inoculated with larvae electroporated with TsNd dsRNA displayed a 83.4% reduction in adult worms and 69.5% reduction in muscle larvae, indicating that electroporation has a higher efficiency than soaking in inhibiting the larval development and survival in mice. Our results showed that silencing TsNd expression in T. spiralis inhibited significantly the larval invasion and survival in host. PMID:26778819

  17. Modelling developmental changes in the carbon and nitrogen budgets of larval brachyuran crabs

    NASA Astrophysics Data System (ADS)

    Anger, K.

    1990-03-01

    The uptake and partitioning of nutritional carbon (C) and nitrogen (N) were studied during the complete larval development of a brachyuran crab, Hyas araneus, reared under constant conditions in the laboratory. Biochemical and physiological data were published in a foregoing paper, and complete budgets of C and N were now constructed from these data. Regression equations describing rates of feeding ( F), growth ( G), respiration ( R), and ammonia excretion ( U) as functions of time during individual larval moult cycles were inserted in a simulation model, in order to analyse time-dependent (i.e. developmental) patterns of variation in these parameters as well as in bioenergetic efficiencies. Absolute daily feeding rates ( F; per individual) as well as carbon and nitrogen-specific rates ( F/C, F/N) are in general maximum in early, and minimum in late stages of individual larval moult cycles (postmoult and premoult, respectively). Early crab zoeae may ingest equivalents of up to ca 40% body C and 30% body N per day, respectively, whereas megalopa larvae usually eat less than 10%. Also growth rates ( G; G/C, G/N) reveal decreasing tendencies both during individual moult cycles and, on the average, in subsequent instars. Conversion of C and N data to lipid and protein, respectively, suggests that in all larval instars there is initially an increase in the lipid: protein ratio. Protein, however, remains clearly the predominant biochemical constituent in larval biomass. The absolute and specific values of respiration ( R; R/C) and excretion ( U; U/N) vary only little during the course of individual moult cycles. Thus, their significance in relation to G increases within the C and N budgets, and net growth efficiency ( K 2) decreases concurrently. Also gross growth and assimilation efficiency ( K 2; A/F) are, in general, maximum in early stages of the moult cycle (postmoult). Biochemical data suggest that lipid utilization efficiency is particularly high in early moult

  18. HABITAT ASSOCIATIONS OF LARVAL FISH IN A LAKE SUPERIOR COASTAL WETLAND

    EPA Science Inventory

    Habitat associations of larval fishes in Great Lakes coastal wetlands (GLCW) are not well documented. To determine the distribution of larval fish in coastal wetlands with regard to location and vegetation characteristics, we used a larval tow-sled to sample four macrohabitat typ...

  19. Larval fish dynamics in spring pools in middle Tennessee

    USGS Publications Warehouse

    Bettoli, Phillip William; Goldsworthy, C.A.

    2011-01-01

    We used lighted larval traps to assess reproduction by fishes inhabiting nine spring pools in the Barrens Plateau region of middle Tennessee between May and September 2004. The traps (n = 162 deployments) captured the larval or juvenile forms of Etheostoma crossopterum (Fringed Darter) (n = 188), Gambusia affinis (Western Mosquitofish) (n = 139), Hemitremia flammea (Flame Chub) (n = 55), the imperiled Fundulus julisia (Barrens Topminnow) (n = 10), and Forbesichthys agassizii (Spring Cavefish) (n = 1). The larval forms of four other species (Families Centrarchidae, Cyprinidae, and Cottidae) were not collected, despite the presence of adults. Larval Barrens Topminnow hatched over a protracted period (early June through late September); in contrast, hatching intervals were much shorter for Fringed Darter (mid-May through early June). Flame Chub hatching began before our first samples in early May and concluded by late-May. Juvenile Western Mosquitofish were collected between early June and late August. Our sampling revealed that at least two species (Flame Chub and Fringed Darter) were able to reproduce and recruit in habitats harboring the invasive Western Mosquitofish, while Barrens Topminnow could not.

  20. Fruit Fly Liquid Larval Diet Technology Transfer and Update

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since October 2006, USDA-ARS has been implementing a fruit fly liquid larval diet technology transfer, which has proceeded according to the following steps: (1) Recruitment of interested groups through request; (2) Establishment of the Material Transfer Agreement (MTA) with ARS; (3) Fruit fly liquid...