The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis

2000 ◽  
Vol 80 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
Cynthia D. Trowbridge
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Shell Length ◽  
Larval Growth ◽  
Model Organism ◽  
Larval Life ◽  
Codium Fragile ◽  
Planktotrophic Larvae ◽  
Algal Diet ◽  
Better Than

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.

Larval and Early Post-Larval Development of Arctica Islandica

1982 ◽  
Vol 62 (4) ◽  
pp. 745-769 ◽  
Author(s):  
R. A. Lutz ◽  
R. Mann ◽  
J. G. Goodsell ◽  
M. Castagna
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Larval Growth ◽  
Ammonium Hydroxide ◽  
Culture Conditions ◽  
Dilute Solution ◽  
Arctica Islandica ◽  
Larval Stages ◽  
Experimental Laboratory ◽  
Rearing Techniques

Mature eggs were stripped from ripe adult specimens of Arctica islandica and exposed to a dilute solution of ammonium hydroxide for various lengths of time before addition of stripped sperm. Larval and early post-larval stages were cultured under experimental laboratory conditions using standard bivalve rearing techniques. Larval cultures were maintained at various controlled temperatures ranging from 8·5 to 14·5 °C. Minimum time to settlement was 32 days at a temperature of approximately 13 °C; at temperatures between 8·5 and 10·0 °C, settlement was not observed until approximately 55 days after fertilization. Larval growth rates were significantly faster at temperatures between 11·0 and 145 °C than at temperatures between 8°C. Morphometry of the larval shell and morphology of the larval hinge apparatus were independent of larval growth rates and experimental culture conditions.

Larval and Early Post-Larval Development of Arctica Islandica

1982 ◽  
Vol 62 (4) ◽  
pp. 745-769 ◽  
Author(s):  
R. A. Lutz ◽  
R. Mann ◽  
J. G. Goodsell ◽  
M. Castagna
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Larval Growth ◽  
Ammonium Hydroxide ◽  
Culture Conditions ◽  
Dilute Solution ◽  
Arctica Islandica ◽  
Larval Stages ◽  
Experimental Laboratory ◽  
Rearing Techniques

Mature eggs were stripped from ripe adult specimens of Arctica islandica and exposed to a dilute solution of ammonium hydroxide for various lengths of time before addition of stripped sperm. Larval and early post-larval stages were cultured under experimental laboratory conditions using standard bivalve rearing techniques. Larval cultures were maintained at various controlled temperatures ranging from 8·5 to 14·5 °C. Minimum time to settlement was 32 days at a temperature of approximately 13 °C; at temperatures between 8·5 and 10·0 °C, settlement was not observed until approximately 55 days after fertilization. Larval growth rates were significantly faster at temperatures between 11·0 and 145 °C than at temperatures between 8°C. Morphometry of the larval shell and morphology of the larval hinge apparatus were independent of larval growth rates and experimental culture conditions.

scholarly journals Short and long term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations

2012 ◽  
Vol 9 (11) ◽  
pp. 15901-15936
Author(s):  
C. J. Gobler ◽  
S. C. Talmage
Keyword(s):  
Larval Development ◽  
Larval Stage ◽  
Growth Rates ◽  
Larval Growth ◽  
Marine Bivalve ◽  
High Co2 ◽  
Legacy Effect ◽  
Bivalve Larvae ◽  
Co2 Concentrations

Abstract. While larval bivalves are highly sensitive to ocean acidification, the basis for this sensitivity and the longer term implications of this sensitivity are unclear. Experiments were performed to assess the short term (days) and long term (months) consequences of larval stage exposure to varying CO2 concentrations for calcifying bivalves. Higher CO2 concentrations depressed both calcification rates assessed using 45Ca uptake and RNA:DNA ratios in Mercenaria mercenaria and Argopecten irradians larvae with RNA:DNA ratios being highly correlated with larval growth rates r2 > 0.9). These findings suggested that high CO2 has a cascading negative physiological impact on bivalve larvae stemming in part from lower calcification rates. Exposure to elevated CO2 during the first four days of larval development significantly depressed A. irradians larval survival rates, while a 10 day exposure later in larval development did not, demonstrating the extreme CO2-sensitivity of bivalve larvae during first days of development. Short- (weeks) and long-term (10 month) experiments revealed that individuals surviving exposure to high CO2 during larval development grew faster when exposed to normal CO2 as juveniles compared to individuals reared under ambient CO2 as larvae. These increased growth rates could not, however, overcome size differences established during larval development, as size deficits of individuals exposed to even moderate levels of CO2 as larvae were evident even after 10 months of growth under normal CO2 concentrations. This `legacy effect' emphasizes the central role larval stage CO2 exposure can play in shaping the success of modern day bivalve populations.

scholarly journals Influence of Different Algal Diets on Larval Growth Rates in the Marine Serpulidae Polychaete Worm Spirobranchus kraussii

2019 ◽  
Vol 77 (2) ◽  
pp. 93-98
Author(s):  
Fatemeh Lavajoo
Keyword(s):  
Survival Rate ◽  
Growth Rates ◽  
Larval Growth ◽  
Single Species ◽  
Growth And Survival ◽  
Food Size ◽  
Algal Diets ◽  
Alternative Sources ◽  
Newly Hatched Larvae ◽  
Algal Diet

Abstract Effects of food availability on larval growth and survival of Spirobranchus kraussii were studied by feeding larvae different algal diets. Newly hatched larvae of S. kraussii were fed four different marine microalgae species, singly and in various mixtures. The best growth was observed when fed C. vulgaris, N. oculata as a single species and mixed-algal diet during day 15 after fertilization. Mortality was low for larvae (max. 5%); survival rate more than 95%. These results suggest that S. kraussii larvae have the capacity to feed using alternative sources of energy, and food size and quality can affect their growth and sustainability.

Dissolved Oxygen Requirements for Embryonic and Larval Development of the Hardshell Clam, Mercenaria mercenaria

1971 ◽  
Vol 28 (3) ◽  
pp. 379-381 ◽  
Author(s):  
George Morrison
Keyword(s):  
Dissolved Oxygen ◽  
Larval Development ◽  
Growth Rates ◽  
Larval Growth ◽  
Mercenaria Mercenaria ◽  
Percent Mortality ◽  
Time Periods ◽  
Oxygen Requirements ◽  
Eggs And Larvae ◽  
Embryonic And Larval Development

Eggs and larvae of Mercenaria mercenaria were exposed to various levels of dissolved oxygen for varying time periods. Larval growth was normal in levels of dissolved oxygen at or above 4.2 mg/liter, but was essentially curtailed in levels at or below 2.4 mg/liter. Larvae survived extended exposures of 1 mg/liter, but showed little growth. Growth rates of larvae transferred to conditions of high dissolved oxygen after various periods of exposure to low dissolved oxygen became normal. Eggs developed normally at oxygen levels down to 0.5 mg/liter. One hundred percent mortality was experienced at 0.2 mg/liter.

scholarly journals Short- and long-term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations

2013 ◽  
Vol 10 (4) ◽  
pp. 2241-2253 ◽  
Author(s):  
C. J. Gobler ◽  
S. C. Talmage
Keyword(s):  
Larval Development ◽  
Larval Stage ◽  
Growth Rates ◽  
Larval Growth ◽  
Marine Bivalve ◽  
High Co2 ◽  
Legacy Effect ◽  
Bivalve Larvae ◽  
Co2 Concentrations

Abstract. While larval bivalves are highly sensitive to ocean acidification, the basis for this sensitivity and the longer-term implications of this sensitivity are unclear. Experiments were performed to assess the short-term (days) and long-term (months) consequences of larval stage exposure to varying CO2 concentrations for calcifying bivalves. Higher CO2 concentrations depressed both calcification rates assessed using 45Ca uptake and RNA : DNA ratios in Mercenaria mercenaria and Argopecten irradians larvae with RNA : DNA ratios being highly correlated with larval growth rates (r2>0.9). These findings suggested that high CO2 has a cascading negative physiological impact on bivalve larvae stemming in part from lower calcification rates. Exposure to elevated CO2 during the first four days of larval development significantly depressed A. irradians larval survival rates, while a 10-day exposure later in larval development did not, demonstrating the extreme CO2 sensitivity of bivalve larvae during first days of development. Short- (weeks) and long-term (10 month) experiments revealed that individuals surviving exposure to high CO2 during larval development grew faster when exposed to normal CO2 as juveniles compared to individuals reared under ambient CO2 as larvae. These increased growth rates could not, however, overcome size differences established during larval development, as size deficits of individuals exposed to even moderate levels of CO2 as larvae were evident even after 10 months of growth under normal CO2 concentrations. This "legacy effect" emphasizes the central role larval stage CO2 exposure can play in shaping the success of modern-day bivalve populations.

scholarly journals amontillado, the Drosophila Homolog of the Prohormone Processing Protease PC2, Is Required During Embryogenesis and Early Larval Development

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 227-237 ◽  
Author(s):  
Lowell Y M Rayburn ◽  
Holly C Gooding ◽  
Semil P Choksi ◽  
Dhea Maloney ◽  
Ambrose R Kidd ◽  
...  
Keyword(s):  
Larval Development ◽  
Secretory Pathway ◽  
Larval Growth ◽  
Peptide Hormones ◽  
Complementation Group ◽  
Prohormone Processing ◽  
Complementation Groups ◽  
Regulated Secretory Pathway ◽  
Processing Protease ◽  
Larval Molt

Abstract 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.

Neurogenesis in the thoracic neuromeres of two crustaceans with different types of metamorphic development

1998 ◽  
Vol 201 (17) ◽  
pp. 2465-2479 ◽  
Author(s):  
S Harzsch ◽  
J Miller ◽  
J Benton ◽  
RR Dawirs ◽  
B Beltz
Keyword(s):  
Embryonic Development ◽  
Larval Development ◽  
Neuronal Development ◽  
Temporal Patterns ◽  
Homarus Americanus ◽  
Spider Crab ◽  
Larval Life ◽  
Larval Stages ◽  
Metamorphic Development ◽  
Embryonic And Larval Development

The mode of embryonic and larval development and the ethology of metamorphosis in the spider crab and the American lobster are very different, and we took advantage of this to compare neuronal development in the two species. The goals of this study were to discover whether the differences in the maturation of the neuromuscular system in the pereopods and the metamorphic changes of motor behavior between the two species are reflected at the level of the developing nervous system ('neurometamorphosis'). Furthermore, we wanted to broaden our understanding of the mechanisms that govern neuronal development in arthropods. Proliferation of neuronal stem cells in thoracic neuromeres 4-8 of the lobster Homarus americanus and the crab Hyas araneus was monitored over the course of embryonic and larval development using the in vivo incorporation of bromodeoxyuridine (BrdU). Neuropil structure was visualized using an antibody against Drosophila synapsin. While proliferation of neuronal precursors has ceased when embryogenesis is 80 % complete (E80%) in the lobster thoracic neuromeres, proliferation of neuroblasts in the crab persists throughout embryonic development and into larval life. The divergent temporal patterns of neurogenesis in the two crustacean species can be correlated with differences in larval life style and in the degree of maturation of the thoracic legs during metamorphic development. Several unusual aspects of neurogenesis reported here distinguish these crustaceans from other arthropods. Lobsters apparently lack a postembryonic period of proliferation in the thoracic neuromeres despite the metamorphic remodeling that takes place in the larval stages. In contrast, an increase in mitotic activity towards the end of embryonic development is found in crabs, and neuroblast proliferation persists throughout the process of hatching into the larval stages. In both E20% lobster embryos and mid-embryonic crabs, expression of engrailed was found in a corresponding set of neurons and putative glial cells at the posterior neuromere border, suggesting that these cells have acquired similar specific identities and might, therefore, be homologous. None of the BrdU-labeled neuroblasts (typically 6-8 per hemineuromere over a long period of embryogenesis) was positive for engrailed at this and subsequent stages. Our findings are discussed in relation to the spatial and temporal patterns of neurogenesis in insects.

scholarly journals Variation in growth and instar number in field and laboratory Manduca sexta

2007 ◽  
Vol 274 (1612) ◽  
pp. 977-981 ◽  
Author(s):  
Joel G Kingsolver
Keyword(s):  
North Carolina ◽  
Body Size ◽  
Manduca Sexta ◽  
Growth Rates ◽  
Developmental Plasticity ◽  
Larval Growth ◽  
Physiological Control ◽  
Larval Instars ◽  
Laboratory Colony ◽  
Early Larval Development

The tobacco hornworm Manduca sexta has been an important model system for understanding physiological control of growth, development and metamorphosis of insects for more than half a century. Like all Manduca , M. sexta typically has five larval instars, with developmental commitment to metamorphosis occurring early in the 5th (final) instar. Here we show that M. sexta from a field population in North Carolina (USA) shows substantial intraspecific variation in the number of larval instars when feeding on a modified artificial diet. Individuals with six instars consistently exhibited slower growth rates during early larval development than individuals with five instars. The frequency of individuals with six instars decreased with increased rearing temperature. In contrast, M. sexta from a laboratory colony consistently had five instars, and had more rapid larval growth rates than M. sexta from the field. We identify a threshold body size at the start of the 5th instar that predicts whether an individual will have five (greater than 600 mg) or six instars (less than 600 mg). Variation in field populations in Manduca provides an important resource for understanding physiological control, developmental plasticity and evolution of growth rate, body size and instar number.

scholarly journals Ovarian growth during larval development of queen and worker of Apis mellifera (Hymenoptera: Apidae): a morphometric and histological study

2003 ◽  
Vol 63 (1) ◽  
pp. 121-127 ◽  
Author(s):  
R. D. Reginato ◽  
C. Cruz-Landim
Keyword(s):  
Weight Gain ◽  
Apis Mellifera ◽  
Larval Development ◽  
Growth Rates ◽  
Histological Study ◽  
Larval Instars ◽  
Ovarian Growth

The present work reports the differences between the ovarian grow in queen and worker larvae of A. mellifera, from the start of differential feeding. The observations made of the growth rates in larvae of both castes showed that the queen and worker larvae have the same rates of cephalic capsule growth from one instar to another but the weight gain is greater in queens. In the same way, the draw areas of ovaries of queens increase more and continuously, while from the 5th instar on the ovaries of workers decrease in size. The decrease is due to a loss of ovariole numbers that starts early in the worker larvae and increases in the 4th-5th instar. The ovarian shape in queens and workers became different in the last larval instars.

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