Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1993
l. In the primitive insect, Thermobia domestica, the two sex-specific proteins of the female are ... more l. In the primitive insect, Thermobia domestica, the two sex-specific proteins of the female are generated by both the fat body and the ovaries.
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1989
l. Ovaries of Thermobia domestica, dissected from inseminated females and incubated with tritiate... more l. Ovaries of Thermobia domestica, dissected from inseminated females and incubated with tritiated amino acids, synthesize labeled proteins, the major fraction of which is indistinguishable from the major vitellogenin secreted by the fat body, when considering the electrophoretic mobility, the polypeptide composition and the immunoreactivity.
The effects of 20-hydroxyecdysone on ovary maturation in the firebrat Therrnobia dornestica were ... more The effects of 20-hydroxyecdysone on ovary maturation in the firebrat Therrnobia dornestica were investigated by in vivo injections of different doses of the hormone on various days of the reproductive cycle. Several females were neck-ligated or treated with precocene I 1 before injection. Experiments were also performed on ovarioles incubated in vitro. It was demonstrated that 20-hydroxyecdysone has direct and dose-dependent effects on the ovary, inducing growth of all the previtellogenic follicles whatever the day of the reproductive cycle, except at times when the ovaries contain follicles undergoing choriogenesis. The major effect of the hormone is the stimulation of young-follicle formation in the anterior part of the previtellarium and the accelerated growth of a set of basal previtellogenic follicles, which reach the critical size required for yolk deposition. However, 20-hydroxyecdysone did not induce cellular differentiation, in particular, the enlargement of the perioocyte space and the development of oocyte microvilli, which normally occur before yolk precursor incorporation. The present results give a better understanding of the temporal relationships between molting and reproductive cycles and also explain the periodicity of ovarian maturation.
International Journal of Insect Morphology and Embryology, 1982
Study of the ultrastructural modifications of the follicular epithelium and of the oocytes during... more Study of the ultrastructural modifications of the follicular epithelium and of the oocytes during the high growth period of the terminal follicles has allowed us to characterize 4 successive phases and to pin-point their synchronisation with the moulting cycles in adults. During phase 1, which takes place near the end of a moulting cycle, the terminal oocytes still undergo previtellogenic growth, followed by the beginning of micropinocytosis and vitellogenesis (lipid droplets at first, then little protein granules), whereas the follicular cells remain joined together. The 2nd phase starts a little before ecdysis; this phase and the third one Correspond to 2 steps of intense vitellogenesis, with simultaneous deposition of lipid and glycoprotein. Endogenous protein synthesis seems to be very limited, unlike most other Apterygota. The follicular cells gradually differentiate proteosynthetic organelles, but continue dividing; the intercellular spaces become greatly distended during the 2nd and 3rd phases. Vitellogenesis can be completed only if insemination takes place at the beginning of each moulting cycle. The 4th phase is marked by the formation of the vitelline envelope and of the chorion, while the follicular cells, once more joined together, become very flat and poor in organelles. Oviposition takes place in the middle of the intermoult period.
... assumptions made over the last decades. Materials and Methods. ... supposed plesiomorphic sta... more ... assumptions made over the last decades. Materials and Methods. ... supposed plesiomorphic state. However, this evolutive hypothesis was not used in the cladistic analyses, the states always being treated as unordered. In contrast to ...
The phylogenetic interrelation-ships of the higher taxa of apterygote hexapods. -Zoologica Script... more The phylogenetic interrelation-ships of the higher taxa of apterygote hexapods. -Zoologica Scripta, 29, 131-156. The phylogeny of the basal hexapods, the so-called apterygote insects, was studied using parsimony analysis procedures. Most analyses took into account 47 characters mainly based on external morphology, and 19 taxa including 14 apterygote representatives, 3 pterygotes and also 2 distantly related myriapods were used as outgroups. The binary and multistate characters are discussed in detail and treated as unordered and equally weighted. Other analyses were performed using a second data set in which 28 characters, based on internal anatomy and already used in a previous work , were added to the first data set. This second matrix was restricted to 12 terminal taxa, the same as those of our previous work. The results of the different analyses are generally congruent. They strongly support the monophyly of several orders (Protura, Collembola, Archaeognatha) and of two groupings (Ectognatha, Dicondylia). Three other assemblages (Ellipura, Diplura, Entognatha) appear as parsimonious phylogenetic hypotheses, but they are never supported by the cladistical analyses and are based on a very small number of autapomorphies; so, the monophyly of each of them is not firmly established. Archaeognatha appears as the sister group of the Dicondylia. The three unresolved representatives of the Zygentoma are found as the sister group of the Pterygota. The results are discussed in the light of current concepts in hexapod phylogeny.
The sensitivity of an apterygote insect to precocene II was investigated for the first time in fe... more The sensitivity of an apterygote insect to precocene II was investigated for the first time in females of Thermobia domestica. Topical applications of this compound, which has been said to possess anti-juvenile hormone activity, were carried out at various times in the postecdysial period of a reproductive cycle, during intense vitellogenesis in the terminal oiicytes. The effects of treatment were observed on mortality, fecundity, insemination and also on the ultrastructure of corpora allata; they depend on the dose used and on the day of treatment. A single application of 10 pg/insect at the beginning of the postecdysial period induces antigonadotropic effects in females reared both with and without males. The effects of precocene add to those of non-insemination, which also elicits inhibition of oocyte maturation. In addition, the cytotoxic action of precocene, leading to degeneration of the corpora allata, which is most probably irreversible, was demonstrated.
The paper proposes an overview of the endoskeletal structures of the head and trunk in the differ... more The paper proposes an overview of the endoskeletal structures of the head and trunk in the different arthropod groups: Chelicerata, Crustacea, Myriapoda and Hexapoda ( Insecta s.l.). Two major endoskeletal systems are reported with their cytological characteristics: those made up of connective tissue derived from muscular tendons, and those consisting of cuticular rods or plates arising from integumentary ingrowths. The morphological value of the various endoskeletal structures, their possible homologies in different groups, and their presumed evolutionary changes are discussed. This survey may be considered as a ®rst step to use morphological characteristics of the endoskeleton in future cladistic analyses to assess the phylogeny of arthropods. q
Bitsch, J. and Bitsch, C. 2010. The tritocerebrum and the clypeolabrum in mandibulate arthropods:... more Bitsch, J. and Bitsch, C. 2010. The tritocerebrum and the clypeolabrum in mandibulate arthropods: segmental interpretations. -Acta Zoologica (Stockholm) 91: 249-266 Different interpretations of the segmental composition of the head in mandibulate arthropods are critically reviewed, with particular focus on three closely associated structures: the tritocerebrum, the stomatogastric nervous system and the clypeolabrum. The main conclusions arising from the different discussions are the following. (1) Each tritocerebral ganglion has a dual composition, clearly discernable in some crustacean and hexapod species, including a dorsal portion connected with the second antennae and a ventral portion connected with the stomatogastric nervous system via the frontal ganglion.
A review of different studies on the phylogenetic relationships of the early Hexapoda lineages sh... more A review of different studies on the phylogenetic relationships of the early Hexapoda lineages shows that analyses based on molecular sequence data have led to labile and sometimes incongruous results, introducing doubt as to the reliability of the cladograms as a whole. In a recent analysis using molecular data, the Collembola, usually considered as early branching hexapods, appear to occupy a position outside the assemblage of Crustacea and Insecta, leading to the rejection of the traditional view of hexapod monophyly. However, many morphological features, as well as the results of cladistic analyses based on morphological and developmental information, contradict these conclusions. More generally, it appears that in the present state of the analytical strategies, hypotheses concerning arthropod phylogenies obtained from morphological and developmental criteria and combined analyses involving molecular and morphological data provide more reliable results than those generated by molecular information alone.
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1993
l. In the primitive insect, Thermobia domestica, the two sex-specific proteins of the female are ... more l. In the primitive insect, Thermobia domestica, the two sex-specific proteins of the female are generated by both the fat body and the ovaries.
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1989
l. Ovaries of Thermobia domestica, dissected from inseminated females and incubated with tritiate... more l. Ovaries of Thermobia domestica, dissected from inseminated females and incubated with tritiated amino acids, synthesize labeled proteins, the major fraction of which is indistinguishable from the major vitellogenin secreted by the fat body, when considering the electrophoretic mobility, the polypeptide composition and the immunoreactivity.
The effects of 20-hydroxyecdysone on ovary maturation in the firebrat Therrnobia dornestica were ... more The effects of 20-hydroxyecdysone on ovary maturation in the firebrat Therrnobia dornestica were investigated by in vivo injections of different doses of the hormone on various days of the reproductive cycle. Several females were neck-ligated or treated with precocene I 1 before injection. Experiments were also performed on ovarioles incubated in vitro. It was demonstrated that 20-hydroxyecdysone has direct and dose-dependent effects on the ovary, inducing growth of all the previtellogenic follicles whatever the day of the reproductive cycle, except at times when the ovaries contain follicles undergoing choriogenesis. The major effect of the hormone is the stimulation of young-follicle formation in the anterior part of the previtellarium and the accelerated growth of a set of basal previtellogenic follicles, which reach the critical size required for yolk deposition. However, 20-hydroxyecdysone did not induce cellular differentiation, in particular, the enlargement of the perioocyte space and the development of oocyte microvilli, which normally occur before yolk precursor incorporation. The present results give a better understanding of the temporal relationships between molting and reproductive cycles and also explain the periodicity of ovarian maturation.
International Journal of Insect Morphology and Embryology, 1982
Study of the ultrastructural modifications of the follicular epithelium and of the oocytes during... more Study of the ultrastructural modifications of the follicular epithelium and of the oocytes during the high growth period of the terminal follicles has allowed us to characterize 4 successive phases and to pin-point their synchronisation with the moulting cycles in adults. During phase 1, which takes place near the end of a moulting cycle, the terminal oocytes still undergo previtellogenic growth, followed by the beginning of micropinocytosis and vitellogenesis (lipid droplets at first, then little protein granules), whereas the follicular cells remain joined together. The 2nd phase starts a little before ecdysis; this phase and the third one Correspond to 2 steps of intense vitellogenesis, with simultaneous deposition of lipid and glycoprotein. Endogenous protein synthesis seems to be very limited, unlike most other Apterygota. The follicular cells gradually differentiate proteosynthetic organelles, but continue dividing; the intercellular spaces become greatly distended during the 2nd and 3rd phases. Vitellogenesis can be completed only if insemination takes place at the beginning of each moulting cycle. The 4th phase is marked by the formation of the vitelline envelope and of the chorion, while the follicular cells, once more joined together, become very flat and poor in organelles. Oviposition takes place in the middle of the intermoult period.
... assumptions made over the last decades. Materials and Methods. ... supposed plesiomorphic sta... more ... assumptions made over the last decades. Materials and Methods. ... supposed plesiomorphic state. However, this evolutive hypothesis was not used in the cladistic analyses, the states always being treated as unordered. In contrast to ...
The phylogenetic interrelation-ships of the higher taxa of apterygote hexapods. -Zoologica Script... more The phylogenetic interrelation-ships of the higher taxa of apterygote hexapods. -Zoologica Scripta, 29, 131-156. The phylogeny of the basal hexapods, the so-called apterygote insects, was studied using parsimony analysis procedures. Most analyses took into account 47 characters mainly based on external morphology, and 19 taxa including 14 apterygote representatives, 3 pterygotes and also 2 distantly related myriapods were used as outgroups. The binary and multistate characters are discussed in detail and treated as unordered and equally weighted. Other analyses were performed using a second data set in which 28 characters, based on internal anatomy and already used in a previous work , were added to the first data set. This second matrix was restricted to 12 terminal taxa, the same as those of our previous work. The results of the different analyses are generally congruent. They strongly support the monophyly of several orders (Protura, Collembola, Archaeognatha) and of two groupings (Ectognatha, Dicondylia). Three other assemblages (Ellipura, Diplura, Entognatha) appear as parsimonious phylogenetic hypotheses, but they are never supported by the cladistical analyses and are based on a very small number of autapomorphies; so, the monophyly of each of them is not firmly established. Archaeognatha appears as the sister group of the Dicondylia. The three unresolved representatives of the Zygentoma are found as the sister group of the Pterygota. The results are discussed in the light of current concepts in hexapod phylogeny.
The sensitivity of an apterygote insect to precocene II was investigated for the first time in fe... more The sensitivity of an apterygote insect to precocene II was investigated for the first time in females of Thermobia domestica. Topical applications of this compound, which has been said to possess anti-juvenile hormone activity, were carried out at various times in the postecdysial period of a reproductive cycle, during intense vitellogenesis in the terminal oiicytes. The effects of treatment were observed on mortality, fecundity, insemination and also on the ultrastructure of corpora allata; they depend on the dose used and on the day of treatment. A single application of 10 pg/insect at the beginning of the postecdysial period induces antigonadotropic effects in females reared both with and without males. The effects of precocene add to those of non-insemination, which also elicits inhibition of oocyte maturation. In addition, the cytotoxic action of precocene, leading to degeneration of the corpora allata, which is most probably irreversible, was demonstrated.
The paper proposes an overview of the endoskeletal structures of the head and trunk in the differ... more The paper proposes an overview of the endoskeletal structures of the head and trunk in the different arthropod groups: Chelicerata, Crustacea, Myriapoda and Hexapoda ( Insecta s.l.). Two major endoskeletal systems are reported with their cytological characteristics: those made up of connective tissue derived from muscular tendons, and those consisting of cuticular rods or plates arising from integumentary ingrowths. The morphological value of the various endoskeletal structures, their possible homologies in different groups, and their presumed evolutionary changes are discussed. This survey may be considered as a ®rst step to use morphological characteristics of the endoskeleton in future cladistic analyses to assess the phylogeny of arthropods. q
Bitsch, J. and Bitsch, C. 2010. The tritocerebrum and the clypeolabrum in mandibulate arthropods:... more Bitsch, J. and Bitsch, C. 2010. The tritocerebrum and the clypeolabrum in mandibulate arthropods: segmental interpretations. -Acta Zoologica (Stockholm) 91: 249-266 Different interpretations of the segmental composition of the head in mandibulate arthropods are critically reviewed, with particular focus on three closely associated structures: the tritocerebrum, the stomatogastric nervous system and the clypeolabrum. The main conclusions arising from the different discussions are the following. (1) Each tritocerebral ganglion has a dual composition, clearly discernable in some crustacean and hexapod species, including a dorsal portion connected with the second antennae and a ventral portion connected with the stomatogastric nervous system via the frontal ganglion.
A review of different studies on the phylogenetic relationships of the early Hexapoda lineages sh... more A review of different studies on the phylogenetic relationships of the early Hexapoda lineages shows that analyses based on molecular sequence data have led to labile and sometimes incongruous results, introducing doubt as to the reliability of the cladograms as a whole. In a recent analysis using molecular data, the Collembola, usually considered as early branching hexapods, appear to occupy a position outside the assemblage of Crustacea and Insecta, leading to the rejection of the traditional view of hexapod monophyly. However, many morphological features, as well as the results of cladistic analyses based on morphological and developmental information, contradict these conclusions. More generally, it appears that in the present state of the analytical strategies, hypotheses concerning arthropod phylogenies obtained from morphological and developmental criteria and combined analyses involving molecular and morphological data provide more reliable results than those generated by molecular information alone.
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