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Wallis H Clark - One of the best experts on this subject based on the ideXlab platform.
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mesendoderm cell and archenteron formation in isolated blastomeres from the shrimp sicyonia ingentis
Developmental Biology, 1994Co-Authors: Philip L Hertzler, Steven W Wang, Wallis H ClarkAbstract:The fate map of 2- and 4-cell-stage Sicyonia ingentis embryos was determined by microinjection of lysyl-rhodamine-dextran into single blastomeres. Microinjected embryos were cultured to the limb bud stage, when the body plan of the Nauplius Larva was evident. The animal blastomere, AB, gave rise to anterior ectoderm, while the vegetal blastomere, CD, gave rise to posterior structures, including the invagination site during gastrulation. The A blastomere gave rise to mirror-image patterns of dorsal-lateral ectoderm, while the B blastomere gave rise to anterior, ventral ectoderm. The C blastomere gave rise to posterior, dorsal-lateral ectoderm, complementary to the A pattern, as well as some naupliar mesoderm. The D blastomere gave rise to mesendoderm, naupliar mesoderm, and some posterior ectoderm. To study the specification of the early blastomeres, they were microsurgically separated and cultured in isolation. Two mesendoderm cells formed in 1/2, 1/4, 1/8, and 1/16 blastomeres in embryos dissociated at the 2-, 4-, 8-, and 16-cell stages, respectively. CD and D blastomeres could be distin-Swished by their larger size and gave rise to the mesendoderm cells. Archenteron formation and elongation of the embryo occurred in CD but not in AB isolates. Isolated blastomeres were recombined in various ways to determine whether their state of commitment could be altered in different cellular environments. Duplicated mesendoderm cells and archenterons formed in CD + CD recombinations, while AB + AB recombinations formed blastulae but did not produce mesendoderm cells and did not invaginate. The normal number of mesendoderm cells and a single archenteron formed in D + AB recombinations, while C + AB recombinations remained as blastulae and did not form mesndoderm cells. The results suggest that the mesendoderm cells are autonomously specified, possibly by cytoplasmic localization at the vegetal pole. The mesendoderm may also function as a signaling region to organize other developmental events.
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cleavage and gastrulation in the shrimp sicyonia ingentis invagination is accompanied by oriented cell division
Development, 1992Co-Authors: Philip L Hertzler, Wallis H ClarkAbstract:Embryos of the penaeoidean shrimp Sicyonia ingentis were examined at intervals during cleavage and gastrulation using antibodies to beta-tubulin and DNA and laser scanning confocal microscopy. Cleavage occurred in a regular pattern within four domains corresponding to the 4-cell-stage blastomeres and resulted in two interlocking bands of cells, each with similar spindle orientations, around a central blastocoel. Right-left asymmetry was evident at the 32-cell-stage, and mirror-image embryos occurred in a 50:50 ratio. Gastrulation was initiated by invagination into the blastocoel at the 62-cell-stage of two mesendoderm cells, which arrested at the 32-cell-stage. Further invagination and expansion of the archenteron during gastrulation was accompanied by rapid and oriented cell division. The archenteron was composed of presumptive naupliar mesoderm and the blastopore was located at the site of the future anus of the Nauplius Larva. In order to trace cell lineages and determine axial relationships, single 2- and 4-cell-stage blastomeres were microinjected with rhodamine-dextran. The results showed that the mesendoderm cells which initiated gastrulation were derived from the vegetal 2-cell-stage blastomere, which could be distinguished by its slightly larger size and the location of the polar bodies. The mesendoderm cells descended from a single vegetal blastomere of the 4-cell-stage. This investigation provides the first evidence for oriented cell division during gastrulation in a simple invertebrate system. Oriented cell division has previously been discounted as a potential morphogenetic force, and may be a common mechanism of invagination in embryos that begin gastrulation with a relatively small number of cells.
Philip L Hertzler - One of the best experts on this subject based on the ideXlab platform.
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mesendoderm cell and archenteron formation in isolated blastomeres from the shrimp sicyonia ingentis
Developmental Biology, 1994Co-Authors: Philip L Hertzler, Steven W Wang, Wallis H ClarkAbstract:The fate map of 2- and 4-cell-stage Sicyonia ingentis embryos was determined by microinjection of lysyl-rhodamine-dextran into single blastomeres. Microinjected embryos were cultured to the limb bud stage, when the body plan of the Nauplius Larva was evident. The animal blastomere, AB, gave rise to anterior ectoderm, while the vegetal blastomere, CD, gave rise to posterior structures, including the invagination site during gastrulation. The A blastomere gave rise to mirror-image patterns of dorsal-lateral ectoderm, while the B blastomere gave rise to anterior, ventral ectoderm. The C blastomere gave rise to posterior, dorsal-lateral ectoderm, complementary to the A pattern, as well as some naupliar mesoderm. The D blastomere gave rise to mesendoderm, naupliar mesoderm, and some posterior ectoderm. To study the specification of the early blastomeres, they were microsurgically separated and cultured in isolation. Two mesendoderm cells formed in 1/2, 1/4, 1/8, and 1/16 blastomeres in embryos dissociated at the 2-, 4-, 8-, and 16-cell stages, respectively. CD and D blastomeres could be distin-Swished by their larger size and gave rise to the mesendoderm cells. Archenteron formation and elongation of the embryo occurred in CD but not in AB isolates. Isolated blastomeres were recombined in various ways to determine whether their state of commitment could be altered in different cellular environments. Duplicated mesendoderm cells and archenterons formed in CD + CD recombinations, while AB + AB recombinations formed blastulae but did not produce mesendoderm cells and did not invaginate. The normal number of mesendoderm cells and a single archenteron formed in D + AB recombinations, while C + AB recombinations remained as blastulae and did not form mesndoderm cells. The results suggest that the mesendoderm cells are autonomously specified, possibly by cytoplasmic localization at the vegetal pole. The mesendoderm may also function as a signaling region to organize other developmental events.
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cleavage and gastrulation in the shrimp sicyonia ingentis invagination is accompanied by oriented cell division
Development, 1992Co-Authors: Philip L Hertzler, Wallis H ClarkAbstract:Embryos of the penaeoidean shrimp Sicyonia ingentis were examined at intervals during cleavage and gastrulation using antibodies to beta-tubulin and DNA and laser scanning confocal microscopy. Cleavage occurred in a regular pattern within four domains corresponding to the 4-cell-stage blastomeres and resulted in two interlocking bands of cells, each with similar spindle orientations, around a central blastocoel. Right-left asymmetry was evident at the 32-cell-stage, and mirror-image embryos occurred in a 50:50 ratio. Gastrulation was initiated by invagination into the blastocoel at the 62-cell-stage of two mesendoderm cells, which arrested at the 32-cell-stage. Further invagination and expansion of the archenteron during gastrulation was accompanied by rapid and oriented cell division. The archenteron was composed of presumptive naupliar mesoderm and the blastopore was located at the site of the future anus of the Nauplius Larva. In order to trace cell lineages and determine axial relationships, single 2- and 4-cell-stage blastomeres were microinjected with rhodamine-dextran. The results showed that the mesendoderm cells which initiated gastrulation were derived from the vegetal 2-cell-stage blastomere, which could be distinguished by its slightly larger size and the location of the polar bodies. The mesendoderm cells descended from a single vegetal blastomere of the 4-cell-stage. This investigation provides the first evidence for oriented cell division during gastrulation in a simple invertebrate system. Oriented cell division has previously been discounted as a potential morphogenetic force, and may be a common mechanism of invagination in embryos that begin gastrulation with a relatively small number of cells.
Ben J Fornshell - One of the best experts on this subject based on the ideXlab platform.
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key for the identification of crustacean nauplii
Organisms Diversity & Evolution, 2006Co-Authors: Hansu Dahms, John A Fornshell, Ben J FornshellAbstract:Abstract The Nauplius is the earliest free-living stage in the development of most crustaceans, except in the majority of the Malacostraca. Several character states of the Nauplius Larva are used as constitutive for the Crustacea as a whole. The Nauplius shows the following structural characters: a median (Nauplius) eye, at least three pairs of head appendages (first and second antennae, where the second antenna bears an arthrite; mandibles), a posteriorly directed fold (the labrum) extending over the mouth, and a cephalic (=Nauplius) shield. Extant taxa such as the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Rhizocephala, Facetotecta, Euphausiacea, and Penaeidea are known to develop free-living nauplii. Other Crustacea show at least some vestige of an ‘egg-Nauplius’ during embryonic development. The diversity of nauplii belonging to major crustacean taxa is briefly described, and a key to these nauplii is provided. The key is also available in digital format, as a JAVA program capable of being modified and expanded as new information arises. The programming structure allows uses in dichotomous or multi-branching formats.
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Key for the identification of crustacean nauplii
2006Co-Authors: Hu Dahms, John A Fornshell, Ben J FornshellAbstract:The Nauplius is the earliest free-living stage in the development of most crustaceans, except in the majority of the Malacostraca. Several character states of the Nauplius Larva are used as constitutive for the Crustacea as a whole. The Nauplius shows the following structural characters: a median (Nauplius) e ye, at least three pairs of head appendages (first and second antennae, where the second antenna bears an arthrite; mandibles), a posteriorly directed fold (the labrum) extending over the mouth, and a cephalic ( = Nauplius) shield. Extant taxa such as the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Rhizocephala, Facetotecta, Euphausiacea, and Penaeidea are known to develop free-living nauplii. Other Crustacea show at least some vestige of an `egg-Nauplius' during embryonic development. The diversity of nauplii belonging to major crustacean taxa is briefly described, and a key to these nauplii is provided. The key is also available in digital format, as a JAVA program capable of being modified and expanded as new information arises. The programming structure allows uses in dichotomous or multi-branching formats. (c) 2005 Gesellschaft fur Biologische Systematik. Published by Elsevier GmbH. All rights reserved
Hansu Dahms - One of the best experts on this subject based on the ideXlab platform.
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key for the identification of crustacean nauplii
Organisms Diversity & Evolution, 2006Co-Authors: Hansu Dahms, John A Fornshell, Ben J FornshellAbstract:Abstract The Nauplius is the earliest free-living stage in the development of most crustaceans, except in the majority of the Malacostraca. Several character states of the Nauplius Larva are used as constitutive for the Crustacea as a whole. The Nauplius shows the following structural characters: a median (Nauplius) eye, at least three pairs of head appendages (first and second antennae, where the second antenna bears an arthrite; mandibles), a posteriorly directed fold (the labrum) extending over the mouth, and a cephalic (=Nauplius) shield. Extant taxa such as the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Rhizocephala, Facetotecta, Euphausiacea, and Penaeidea are known to develop free-living nauplii. Other Crustacea show at least some vestige of an ‘egg-Nauplius’ during embryonic development. The diversity of nauplii belonging to major crustacean taxa is briefly described, and a key to these nauplii is provided. The key is also available in digital format, as a JAVA program capable of being modified and expanded as new information arises. The programming structure allows uses in dichotomous or multi-branching formats.
John A Fornshell - One of the best experts on this subject based on the ideXlab platform.
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key for the identification of crustacean nauplii
Organisms Diversity & Evolution, 2006Co-Authors: Hansu Dahms, John A Fornshell, Ben J FornshellAbstract:Abstract The Nauplius is the earliest free-living stage in the development of most crustaceans, except in the majority of the Malacostraca. Several character states of the Nauplius Larva are used as constitutive for the Crustacea as a whole. The Nauplius shows the following structural characters: a median (Nauplius) eye, at least three pairs of head appendages (first and second antennae, where the second antenna bears an arthrite; mandibles), a posteriorly directed fold (the labrum) extending over the mouth, and a cephalic (=Nauplius) shield. Extant taxa such as the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Rhizocephala, Facetotecta, Euphausiacea, and Penaeidea are known to develop free-living nauplii. Other Crustacea show at least some vestige of an ‘egg-Nauplius’ during embryonic development. The diversity of nauplii belonging to major crustacean taxa is briefly described, and a key to these nauplii is provided. The key is also available in digital format, as a JAVA program capable of being modified and expanded as new information arises. The programming structure allows uses in dichotomous or multi-branching formats.
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Key for the identification of crustacean nauplii
2006Co-Authors: Hu Dahms, John A Fornshell, Ben J FornshellAbstract:The Nauplius is the earliest free-living stage in the development of most crustaceans, except in the majority of the Malacostraca. Several character states of the Nauplius Larva are used as constitutive for the Crustacea as a whole. The Nauplius shows the following structural characters: a median (Nauplius) e ye, at least three pairs of head appendages (first and second antennae, where the second antenna bears an arthrite; mandibles), a posteriorly directed fold (the labrum) extending over the mouth, and a cephalic ( = Nauplius) shield. Extant taxa such as the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Rhizocephala, Facetotecta, Euphausiacea, and Penaeidea are known to develop free-living nauplii. Other Crustacea show at least some vestige of an `egg-Nauplius' during embryonic development. The diversity of nauplii belonging to major crustacean taxa is briefly described, and a key to these nauplii is provided. The key is also available in digital format, as a JAVA program capable of being modified and expanded as new information arises. The programming structure allows uses in dichotomous or multi-branching formats. (c) 2005 Gesellschaft fur Biologische Systematik. Published by Elsevier GmbH. All rights reserved
