Triggering larval settlement behaviour and metamorphosis of the burrowing ghost shrimp, Lepidophthalmus siriboia (Callianassidae): do cues matter?

2016 ◽  
Vol 67 (3) ◽  
pp. 291 ◽  
Author(s):  
Kácia Letícia de Noronha Campos ◽  
Fernando Araújo Abrunhosa ◽  
Darlan de Jesus de Brito Simith
Keyword(s):  
Larval Settlement ◽  
Environmental Cues ◽  
Decapod Crustaceans ◽  
Muddy Sand ◽  
Chemical Substances ◽  
Ghost Shrimp ◽  
Exogenous Cues ◽  
Settlement And Metamorphosis ◽  
Disturbed Habitats ◽  
Stimulation Of

Larval settlement and metamorphosis of many estuarine decapod crustaceans are triggered by environmental cues and chemical substances produced by the conspecific population. Here, we examined the influence of substrata and conspecific cues on the stimulation of the megalopal stage of the burrowing ghost shrimp (Lepidophthalmus siriboia) in the following five treatments: (1) adult-conditioned seawater (ACSW), (2) filtered seawater (FSW) + sand, (3) FSW + muddy sand (MS), (4) ACSW + MS and (5) FSW without cues (control). All megalopae settled and exhibited burrowing behaviour in the treatments containing substratum. The percentage of metamorphosis to juvenile was high (≥96%) in all treatments. Megalopae developed significantly faster in the control (5.7days, ±0.9s.d.) than in the remaining treatments (6.8–7.3 days). These findings demonstrated that settlement of L. siriboia megalopae is strongly induced by substrata, whereas their metamorphosis occurs irrespective of the presence or type of exogenous cues associated with estuarine habitat and conspecific adults. This suggests certain flexibility concerning the ontogenetic stage at which recruitment to the benthos occurs. The independence of metamorphic inducers should be important for colonisation of new estuarine areas as well as for recovery and maintenance of viable populations in disturbed habitats where callianassid ghost shrimps are heavily exploited.

scholarly journals Identification of the Neuropeptide Precursor Genes Potentially Involved in the Larval Settlement in the Echiuran Worm Urechis unicinctus

2020 ◽  
Author(s):  
Xitan Hou ◽  
Zhenkui Qin ◽  
Maokai Wei ◽  
Zhong Fu ◽  
Ruonan Liu ◽  
...  
Keyword(s):  
De Novo ◽  
Marine Invertebrate ◽  
Larval Settlement ◽  
Life Cycles ◽  
Apical Organ ◽  
Neurosecretory System ◽  
Environmental Cues ◽  
Urechis Unicinctus ◽  
Neuroendocrine Mechanisms ◽  
Settlement And Metamorphosis

Abstract Background: In marine invertebrate life cycles, which often consist of planktonic larval and benthonic adult stages, settlement of the free-swimming larva to the sea floor in response to environmental cues is a key life cycle transition. Settlement is regulated by a specialized sensory–neurosecretory system, the larval apical organ. The neuroendocrine mechanisms through which the apical organ transduces environmental cues into behavioral responses during settlement are not fully understood yet.Results: In this study, a total of 54 neuropeptide precursors (pNPs) were identified in the Urechis unicinctus larva and adult transcriptome databases using local BLAST and de novo prediction, of which 10 pNPs belonging to the ancient eumetazoa, 23 pNPs belonging to the ancient bilaterian, 3 pNPs belonging to the ancient protostome, 10 pNPs exclusive in lophotrochozoa, 3 pNPs exclusive in annelid, and 5 pNPs only found in U. unicinctus. Furthermore, four pNPs (MIP, FRWamide, FxFamide and FILamide) which may be associated with the settlement and metamorphosis of U. unicinctus larvae were verified successfully by qRT-PCR. Whole-mount in situ hybridization results showed that all the four pNPs were expressed in the region of the apical organ of the larva, and the positive signals were also detected in the ciliary band and abdomen chaetae. We speculated that these pNPs may regulate the movement of larval cilia and chaeta by sensing external attachment signals.Conclusions: This study represents the first comprehensive identification of neuropeptides in Echiura, and would contribute to a complete understanding on the roles of various neuropeptides in larval settlement of most marine benthonic invertebrates.

scholarly journals Identification of the neuropeptide precursor genes potentially involved in the larval settlement in the Echiuran worm Urechis unicinctus

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Xitan Hou ◽  
Zhenkui Qin ◽  
Maokai Wei ◽  
Zhong Fu ◽  
Ruonan Liu ◽  
...  
Keyword(s):  
Marine Invertebrate ◽  
Larval Settlement ◽  
Life Cycles ◽  
Apical Organ ◽  
Neurosecretory System ◽  
Environmental Cues ◽  
Urechis Unicinctus ◽  
Neuroendocrine Mechanisms ◽  
Settlement And Metamorphosis

Abstract Background In marine invertebrate life cycles, which often consist of planktonic larval and benthonic adult stages, settlement of the free-swimming larva to the sea floor in response to environmental cues is a key life cycle transition. Settlement is regulated by a specialized sensory–neurosecretory system, the larval apical organ. The neuroendocrine mechanisms through which the apical organ transduces environmental cues into behavioral responses during settlement are not fully understood yet. Results In this study, a total of 54 neuropeptide precursors (pNPs) were identified in the Urechis unicinctus larva and adult transcriptome databases using local BLAST and NpSearch prediction, of which 10 pNPs belonging to the ancient eumetazoa, 24 pNPs belonging to the ancient bilaterian, 3 pNPs belonging to the ancient protostome, 9 pNPs exclusive in lophotrochozoa, 3 pNPs exclusive in annelid, and 5 pNPs only found in U. unicinctus. Furthermore, four pNPs (MIP, FRWamide, FxFamide and FILamide) which may be associated with the settlement and metamorphosis of U. unicinctus larvae were analysed by qRT-PCR. Whole-mount in situ hybridization results showed that all the four pNPs were expressed in the region of the apical organ of the larva, and the positive signals were also detected in the ciliary band and abdomen chaetae. We speculated that these pNPs may regulate the movement of larval cilia and chaeta by sensing external attachment signals. Conclusions This study represents the first comprehensive identification of neuropeptides in Echiura, and would contribute to a complete understanding on the roles of various neuropeptides in larval settlement of most marine benthonic invertebrates.

scholarly journals Identification of the Neuropeptide Precursor Genes Potentially Involved in the Larval Settlement in the Echiuran Worm Urechis unicinctus

2020 ◽  
Author(s):  
Xitan Hou ◽  
Zhenkui Qin ◽  
Maokai Wei ◽  
Zhong Fu ◽  
Ruonan Liu ◽  
...  
Keyword(s):  
Marine Invertebrate ◽  
Larval Settlement ◽  
Life Cycles ◽  
Apical Organ ◽  
Neurosecretory System ◽  
Environmental Cues ◽  
Urechis Unicinctus ◽  
Neuroendocrine Mechanisms ◽  
Settlement And Metamorphosis

Abstract Background: In marine invertebrate life cycles, which often consist of planktonic larval and benthonic adult stages, settlement of the free-swimming larva to the sea floor in response to environmental cues is a key life cycle transition. Settlement is regulated by a specialized sensory–neurosecretory system, the larval apical organ. The neuroendocrine mechanisms through which the apical organ transduces environmental cues into behavioral responses during settlement are not fully understood yet.Results: In this study, a total of 54 neuropeptide precursors (pNPs) were identified in the Urechis unicinctus larva and adult transcriptome databases using local BLAST and NpSearch prediction, of which 10 pNPs belonging to the ancient eumetazoa, 24 pNPs belonging to the ancient bilaterian, 3 pNPs belonging to the ancient protostome, 9 pNPs exclusive in lophotrochozoa, 3 pNPs exclusive in annelid, and 5 pNPs only found in U. unicinctus. Furthermore, four pNPs (MIP, FRWamide, FxFamide and FILamide) which may be associated with the settlement and metamorphosis of U. unicinctus larvae were analysed by qRT-PCR. Whole-mount in situ hybridization results showed that all the four pNPs were expressed in the region of the apical organ of the larva, and the positive signals were also detected in the ciliary band and abdomen chaetae. We speculated that these pNPs may regulate the movement of larval cilia and chaeta by sensing external attachment signals.Conclusions: This study represents the first comprehensive identification of neuropeptides in Echiura, and would contribute to a complete understanding on the roles of various neuropeptides in larval settlement of most marine benthonic invertebrates.

scholarly journals A Functional Connection between the Circadian Clock and Hormonal Timing in Arabidopsis

Genes ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 567 ◽  
Author(s):  
Manjul Singh ◽  
Paloma Mas
Keyword(s):  
Circadian Clock ◽  
Biological Significance ◽  
Feedback Regulation ◽  
Environmental Cues ◽  
Hormone Signaling ◽  
Functional Connection ◽  
The Earth ◽  
Exogenous Cues ◽  
Rotation Of The Earth ◽  
Molecular Components

The rotation of the Earth entails changes in environmental conditions that pervasively influence an organism’s physiology and metabolism. An internal cellular mechanism known as the circadian clock acts as an internal timekeeper that is able to perceive the changes in environmental cues to generate 24-h rhythms in synchronization with daily and seasonal fluctuations. In plants, the circadian clock function is particularly important and regulates nearly every aspect of plant growth and development as well as proper responses to stresses. The circadian clock does not function in isolation but rather interconnects with an intricate network of different pathways, including those of phytohormones. Here, we describe the interplay of the circadian clock with a subset of hormones in Arabidopsis. The molecular components directly connecting the circadian and hormone pathways are described, highlighting the biological significance of such connections in the control of growth, development, fitness, and survival. We focus on the overlapping as well as contrasting circadian and hormonal functions that together provide a glimpse on how the Arabidopsis circadian system regulates hormone function in response to endogenous and exogenous cues. Examples of feedback regulation from hormone signaling to the clock are also discussed.

Calcified macroalgae and their bacterial community in relation to larval settlement and metamorphosis of reef-building coral Pocillopora damicornis

2020 ◽  
Vol 97 (1) ◽  
Author(s):  
Fangfang Yang ◽  
Jiahao Mo ◽  
Zhangliang Wei ◽  
Lijuan Long
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Community Composition ◽  
Larval Settlement ◽  
Pocillopora Damicornis ◽  
Principal Coordinates Analysis ◽  
Principal Coordinates ◽  
Coral Reef Ecosystems ◽  
Settlement And Metamorphosis ◽  
Invertebrate Larvae

ABSTRACT Calcified macroalgae play an important role in the settlement and metamorphosis of invertebrate larvae in coral reef ecosystems. However, little is known about the algal-associated bacterial communities and their effects on larval settlement. In this study, the responses of larvae of the coral Pocillopora damicornis to calcified algae (Porolithon onkodes, Halimeda cylindracea, Halimeda opuntia and Amphiroa fragilissima) were evaluated. The results revealed that Por. onkodes and H. cylindracea significantly enhanced the rates of settlement and metamorphosis, whereas fewer larvae settled on Am. fragilissima and H. opuntia. Amplicon pyrosequencing of the V3–V4 region of 16S rDNA was applied to investigate the relationship between algal bacterial community and larval settlement. Principal coordinates analysis demonstrated that the bacterial community composition of H. opuntia was more similar to that of Am. fragilissima, but clearly distinct from those of H. cylindracea and Por. onkodes. Furthermore, the relative abundances of bacteria were highly diverse among different algae. H. opuntia had higher percentages of Thalassobius, Pelagibius and SM1A02, whereas the abundances of Mycoplasma and Suttonella were significantly higher in H. cylindracea than other algae. Our results showed that larval settlement/metamorphosis was strongly correlated with the bacterial community composition and with the relative abundance of a few operational taxonomic units.

scholarly journals Bacterial Nucleobases Synergistically Induce Larval Settlement and Metamorphosis in the Invasive MusselMytilopsis sallei

2019 ◽  
Vol 85 (16) ◽  
Author(s):  
Jian He ◽  
Qi Dai ◽  
Yuxuan Qi ◽  
Pei Su ◽  
Miaoqin Huang ◽  
...  
Keyword(s):  
Marine Invertebrates ◽  
Larval Settlement ◽  
Aquatic Systems ◽  
Substrate Selection ◽  
Content Type ◽  
Dreissenid Mussels ◽  
Settlement And Metamorphosis ◽  
Environmental Bacteria ◽  
Fouling Organisms ◽  
Chemical Mediators

ABSTRACTMarine bacterial biofilms have long been recognized as potential inducers of larval settlement and metamorphosis in marine invertebrates, but few chemical cues from bacteria have been identified. Here, we show that larval settlement and metamorphosis of an invasive fouling mussel,Mytilopsis sallei, could be induced by biofilms of bacteria isolated from its adult shells and other substrates from the natural environment. One of the strains isolated,Vibrio owensiiMS-9, showed strong inducing activity which was attributed to the release of a mixture of nucleobases including uracil, thymine, xanthine, hypoxanthine, and guanine into seawater. In particular, the synergistic effect of hypoxanthine and guanine was sufficient for the inducing activity ofV. owensiiMS-9. The presence of two or three other nucleobases could enhance, to some extent, the activity of the mixture of hypoxanthine and guanine. Furthermore, we determined that bacteria producing higher concentrations of nucleobases were more likely to induce larval settlement and metamorphosis ofM. salleithan were bacteria producing lower concentrations of nucleobases. The present study demonstrates that bacterial nucleobases play an important role in larval settlement and metamorphosis of marine invertebrates. This provides new insights into our understanding of the role of environmental bacteria in the colonization and aggregation of invasive fouling organisms and of the metabolites used as chemical mediators in cross-kingdom communication within aquatic systems.IMPORTANCEInvasive species are an increasingly serious problem globally. In aquatic ecosystems, invasive dreissenid mussels are well-known ecological and economic pests because they appear to effortlessly invade new environments and foul submerged structures with high-density aggregations. To efficiently control exotic mussel recruitment and colonization, the need to investigate the mechanisms of substrate selection for larval settlement and metamorphosis is apparent. Our work is one of very few to experimentally demonstrate that compounds produced by environmental bacteria play an important role in larval settlement and metamorphosis in marine invertebrates. Additionally, this study demonstrates that bacterial nucleobases can be used as chemical mediators in cross-kingdom communication within aquatic systems, which will enhance our understanding of how microbes induce larval settlement and metamorphosis of dreissenid mussels, and it furthermore may allow the development of new methods for application in antifouling.

Sign in / Sign up

Export Citation Format

Share Document