Egg-shell formation in trematodes and cestodes

Smyth, J. D.; Clegg, J. A.

doi:10.1016/0014-4894(59)90027-x

Cited by 192 publications

(79 citation statements)

References 39 publications

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“…The structure of this shell and its formation have been studied most intensively in species of the Trematoda and Cestoidea (Smyth & Clegg, 1959;Wittrock, 1982 ;and others). As far as the Turbellaria is concerned, several investigators reported that the eggshells of triclads and rhabdocoels are formed with globules extruded from yolk cells (Yanagita & Yamamoto, 1981 ;Bunke, 1982 ;and others) .…”

Section: Introductionmentioning

confidence: 99%

Eggshell formation in polyclads (Turbellaria)

Ishida

Teshirogi

1986

Hydrobiologia

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Eggshell formation in polyclads was studied by means of transmission electron microscopy and histochemistry. Shell-forming granules (SFG) in the egg, as well as secretions of shell glands (SGS), play roles in eggshell formation. As the oocytes pass through the portion of the female tract where the shell glands open, they are surronded by a two-layered envelope of SGS . This envelope prevents the dispersion of SFGs discharged after oviposition, and its inner layer participates in eggshell formation with the SFGs . In Pseudostylochus sp ., most SFGs consist of five parts . Similarities in staining between the parts of the SFGs and the parts of the eggshell indicate that discrete parts of the shell are derived from specific SFG components . Hardening of the eggshell and egg-plate matrix takes place through primary tanning of a sclerotin-like protein .

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Section: Introductionmentioning

confidence: 99%

Eggshell formation in polyclads (Turbellaria)

Ishida

Teshirogi

1986

Hydrobiologia

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“…Presence of proline in both the shell gland and the egg shell suggests that the protein may be collagenous (Smyth & Clegg, 1959) ; but the absence of hydroxyproline negates this supposition .…”

Section: Resultsmentioning

confidence: 96%

“…However, the intensity of the reaction for protein is much reduced in the egg shell suggesting that most of the reactive groups are reduced after stabilization, as in the egg shell of helminths (Smyth & Clegg, 1959) and cuticle of insects (Hackman, 1971) . However, the egg shell shows only feeble colour to ninhydrin ; possibly amino -= negative; ± = doubtful ; + = moderately positive ; ++ = positive ; +++ = intensely positive.…”

Section: Resultsmentioning

confidence: 99%

Egg envelopes of Streptocephalus dichotomus Baird: A structural and histochemical study

Munuswamy

Subramoniam

1984

Hydrobiologia

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The origin, ultrastructure and histochemical properties of the egg membranes in the South Indian anostracan, Streptocephalus dichotomus have been studied . The egg morphology and the ultrastructure of the tertiary membrane of this phyllopod crustacean have been examined both by scanning and transmission electron microscopy . Scanning electron microscopic observations on the egg surface reveal the characteristic ridges on the egg surface with pores . Similarly, the tertiary egg shell of S. dichotomus consists of two distinct layers, an outer cortex and an inner alveolar layer. There are specific differences in the structure and in the relationship of one layer to the other . The alveolar layer is characterised by large lipid droplets and an alveolar mesh . These two layers termed as tertiary layers are secreted by maternal shell glands . The outer tertiary egg layers are phenolically tanned, the precursor materials for tanning being derived from shell gland secretions .

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“…As an extremely versatile and widespread component of invertebrate biochemical systems, L-dopa can be synthesized from tyrosine by at least three distinct enzymatic pathways (Waite, 1992). In invertebrates alone, L-dopa and its metabolites are involved in processes as diverse as egg capsule formation (Smyth and Clegg, 1959), silk production (Kramer et al, 1989), immunity (Nappi et al, 1991) and predator defence (Prota et al, 1981). Since Ldopaminergic pathways are involved in both insect behavioural plasticity (Goldstein and Camhi, 1991;Kostowski et al, 1975) and learning (Zhang et al, 2007), perhaps it is not surprising that an Ldopa analogue is implicated in locust phase transmission.…”

Section: Discussionmentioning

confidence: 99%

Swarm formation in the desert locust Schistocerca gregaria:isolation and NMR analysis of the primary maternal gregarizing agent

Miller

Islam

Claridge

et al. 2008

Journal of Experimental Biology

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SUMMARYDepending on their rearing density, female desert locusts Schistocerca gregaria epigenetically endow their offspring with differing phenotypes. To identify the chemical basis for such maternal transmission, we compared solitarious and gregarious locust egg pod foam using high performance liquid chromatography (HPLC). We revealed causal relationships between foam chemistry and hatchling phenotype (phase state) by iteratively applying HPLC fractions from gregarious locust egg foam extracts to solitarious eggs and assessing resulting hatchlings with a behavioural bioassay involving logistic regression. Selection and application of increasingly specific HPLC fractions allowed us to isolate compounds with gregarizing properties. Hatchling gregarization was triggered only by certain fractions and was dose dependent. In a final series of experiments, we characterized the most specific gregarizing fraction by nuclear magnetic resonance (NMR) spectroscopy. Here we present tentative structural features of the primary locust maternal gregarizing agent, which appears to be an alkylated L-dopa analogue. In addition, we propose a mechanism for phase-dependent regulation of this compoundʼs activity.

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Egg-shell formation in trematodes and cestodes

Cited by 192 publications

References 39 publications

Eggshell formation in polyclads (Turbellaria)

Eggshell formation in polyclads (Turbellaria)

Egg envelopes of Streptocephalus dichotomus Baird: A structural and histochemical study

Swarm formation in the desert locust Schistocerca gregaria:isolation and NMR analysis of the primary maternal gregarizing agent

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