Studies on the function of the oxyurid egg-shell

Parasitology ◽  
1980 ◽  
Vol 81 (1) ◽  
pp. 103-113 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Embryonic Development ◽  
Water Loss ◽  
Complex Structure ◽  
Permeability Barrier ◽  
Lipid Layer ◽  
Insect Eggs ◽  
Egg Shells ◽  
Syphacia Obvelata ◽  
Egg Shell ◽  
Aspiculuris Tetraptera

SUMMARYThe egg-shell of Hammerschmidtiella diesingi and Aspiculuris tetraptera reduces the rate of water loss from the egg when exposed to desiccation. Staining of the enclosed larva by acid fuchsin and the collapse of eggs exposed to desiccation indicate that the permeability barrier is heat labile. This suggests that the lipid layer is the main permeability barrie of the shell. The complex structure of the uterine layers has a similar morphology to the respiratory structures of the chorion of some insect eggs. Reflections from the shell, the rate of embryonic development under various conditions and the penetration of lead ions indicate that the shell does not trap a layer of air when immersed in water and the uterine layers cannot, therefore, function as a plastron network. Calculations indicate that if diffusion is limited to the pores in the external uterine layer, the area available for gaseous exchange is reduced by 85·5% in H. diesingi, 95·6% in A. tetraptera and 96·8% in Syphacia obvelata. It is suggested that the uterine layers of oxyurid egg-shells function in a similar fashion to the pores in bird egg-shells and the aeropyles in the chorion of insect egg-shells which do not possess plastron networks. These structures reduce water loss from the egg whilst ensuring an adequate supply of oxygen for embryonic development.

The structure and formation of the egg-shell of Syphacia obvelata Rudolphi (Nematoda: Oxyurida)

Parasitology ◽  
1979 ◽  
Vol 79 (1) ◽  
pp. 13-28 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Reproductive System ◽  
Self Assembly ◽  
Complex Structure ◽  
Assembly Process ◽  
Lipid Layer ◽  
Syphacia Obvelata ◽  
Egg Shell ◽  
Discrete Spaces

SUMMARYThe egg of Syphacia obvelata is a flattened elipsoid. The egg-shell consists of 5 layers: external uterine layer, internal uterine layer, vitelline layer, chitinous layer and lipid layer. An operculum is present at one pole of the egg. The opercular groove consists of a break in the uterine layers and the modification of the chitinous layer by the deposition of lipoprotein material. On the curved side of the egg the uterine layers are modified to form alternate ridges and depressions. Discrete spaces are present in the internal uterine layer between the ridges. These are open to the exterior via pores in the external uterine layer. The structure of the uterine layers is quite different on the flattened side of the egg. The morphology of the reproductive system and the formation of the egg-shell is described. It is suggested that the complex structure of the uterine layers of oxyurids forms by a self-assembly process.

The structure of the egg-shell of Aspiculuris tetraptera Schulz (Nematoda: Oxyuroidea)

Parasitology ◽  
1979 ◽  
Vol 78 (2) ◽  
pp. 145-154 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Lipid Layer ◽  
Freeze Etching ◽  
Uterine Secretion ◽  
Egg Shell ◽  
Aspiculuris Tetraptera

The egg of Aspiculuris tetraptera is an ellipsoid measuring 93 × 40 µm. The shell consists of 5 layers: the external uterine layer, internal uterine layer, vitelline layer, chitinous layer and the lipid layer. This nomenclature is based upon the formation and histochemistry of the shell layers. The internal uterine layer contains a system of interconnecting spaces, partly filled by uterine secretion, which open to the exterior of the egg via breaks in the external uterine layer. The surface of the egg is covered by a system of interconnecting grooves. Freeze-etching reveals that the internal uterine layer is open to the exterior via pores, which open into the grooves. Rod-shaped particles are also revealed in the external uterine layer. The operculum of the egg consists of a modification of the uterine and chitinous layers of the shell.

Studies of the Egg of Bacillus libanicus (Orthoptera, Phasmidae)

1950 ◽  
Vol s3-91 (14) ◽  
pp. 195-203
Author(s):  
A. MOSCONA
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Embryonic Development ◽  
Moisture Content ◽  
Mineral Content ◽  
Calcium Deficiency ◽  
Egg Shells ◽  
Egg Shell ◽  
Short Time ◽  
Initial Mineral

1. Weight, moisture content, and mineral content of freshly laid and of fully developed eggs of Bacillus libanicus (Uv.) were studied. During development of the embryo the egg-shell loses 19 per cent, of its initial mineral content, while the weight of mineral materials in the embryo increases correspondingly. 2. These changes can be explained only as resulting from transfer of minerals from the shell to the embryo. The mineral materials are derived from the calcium carbonate layer of the shell, which, owing to this loss, becomes thinner during embryonic development. 3. It is suggested that the mechanism of this transfer is based on the production of bicarbonate by the reaction of water and carbon dioxide, given off by the embryo, with the calcium carbonate of the shell. 4. Experimental calcium deficiency in the egg-shells results in a marked lowering of the viability of the embryos; although embryogenesis may sometimes proceed till the hatching stage, the few emerging nymphs survive only for a short time. 5. The possible occurrence of mineral transfer in other phasmid eggs is indicated.

The tylenchid (Nematoda) egg shell: structure, composition and permeability

Parasitology ◽  
1976 ◽  
Vol 72 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Alan F. Bird ◽  
M. A. McClure
Keyword(s):  
Basic Structure ◽  
Vitelline Membrane ◽  
Chemical Components ◽  
Rotylenchulus Reniformis ◽  
Lipid Layer ◽  
Tylenchulus Semipenetrans ◽  
Different Temperatures ◽  
Egg Shells ◽  
Egg Shell ◽  
Lipid Layers

SummaryThe fine structure of egg shells of four different genera belonging to the order Tylenchida has been examined. The species examined were Meloidogyne javanica, Rotylenchulus reniformis, Tylenchulus semipenetrans and Pratylenchus minyus. They are all similar in their basic structure, being composed of vitelline membrane, chitin and lipid layers, but there is considerable variability in the thickness of these layers.We have retained the conventional nomenclature because of its convenience, but it is clear that these layers have a variety of chemical components. However, they do appear to contain the compounds from which they take their name. Thus chitin occurs in the chitin layer, and lipid in the lipid layer. The latter is removed by the technique used in isolating the shell from the egg. Chemical analysis of the hydrolysis products of these shells has revealed a high (35 %) proline content which appears to be a characteristic of those nematode egg shells which have been examined so far. These analyses and treatment with enzymes indicate that the chitin layer is a chitin–protein complex.Experiments on the permeability of eggs of M. javanica at different temperatures indicate that changes in permeability are not due to the melting of a single lipid with a distinct melting point as had been thought in the past. We have found that Arrhenius activation energies calculated from the two slopes of an Arrhenius plot were 17·8 kcal/mol and 43·0 kcal/mol respectively, the transition from one to the other taking place at 62°C. We think that these changes are due to changes in the properties of lipoprotein membranes in the lipid layer. These membranes appear to be of paramount importance in controlling the permeability of the nematode egg shell.

Oogenesis and egg-shell formation in Aspiculuris tetraptera Schulz (Nematoda: Oxyuroidea)

Parasitology ◽  
1979 ◽  
Vol 78 (2) ◽  
pp. 131-143 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Vitelline Membrane ◽  
Shell Formation ◽  
Perivitelline Space ◽  
Lipid Layer ◽  
Cytoplasmic Inclusions ◽  
Inner Surface ◽  
Egg Shell ◽  
Aspiculuris Tetraptera ◽  
Lipid Layers

SUMMARYThe ovary of Aspiculuris tetraptera has a prominent terminal cap cell. This is considered to be part of the ovarian epithelium. Oogonia detach from the short rachis and increase in size from 6 to 60 μm; accumulating hyaline granules, shell granules and glycogen. The hyaline granules persist in the egg cytoplasm after shell formation has been completed and are considered to be lipoprotein yolk. The shell granules contribute to the non-chitin fraction of the chitinous layer. A classification of the cytoplasmic inclusions of the nematode oocyte is proposed. Upon fertilization a vitelline membrane is formed which constitutes the vitelline layer of the egg-shell. The chitinous layer is secreted in the perivitelline space, between the vitelline layer and the egg oolemma. Upon completion of chitinous layer synthesis, the egg cytoplasm contracts away from its inner surface. The material of the lipid layer is secreted at the surface of the egg cytoplasm and adheres to the inner surface of the chitinous layer. During secretion of the chitinous and lipid layers by the egg cytoplasm, the uterine cells secrete the unit membrane-like external uterine layer and the crystalline internal uterine layer. A complex system of interconnecting spaces develops in the internal uterine layer. This system is open to the exterior via breaks in the external uterine layer. There is no direct involvement of the uterine cells in the formation of this structure.

The tylenchid (Nematoda) egg shell: structure, composition and permeability

Parasitology ◽  
1976 ◽  
Vol 72 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Alan F. Bird ◽  
M. A. McClure
Keyword(s):  
Basic Structure ◽  
Vitelline Membrane ◽  
Chemical Components ◽  
Rotylenchulus Reniformis ◽  
Lipid Layer ◽  
Tylenchulus Semipenetrans ◽  
Different Temperatures ◽  
Egg Shells ◽  
Egg Shell ◽  
Lipid Layers

The fine structure of egg shells of four different genera belonging to the order Tylenchida has been examined. The species examined were Meloido-gyne javanica, Rotylenchulus reniformis, Tylenchulus semipenetrans and Pratylenchus minyus. They are all similar in their basic structure, being composed of vitelline membrane, chitin and lipid layers, but there is considerable variability in the thickness of these layers.We have retained the conventional nomenclature because of its convenience, but it is clear that these layers have a variety of chemical components. However, they do appear to contain the compounds from which they take their name. Thus chitin occurs in the chitin layer, and lipid in the lipid layer. The latter is removed by the technique used in isolating the shell from the egg. Chemical analysis of the hydrolysis products of these shells has revealed a high (35 %) proline content which appears to be a characteristic of those nematode egg shells which have been examined so far. These analyses and treatment with enzymes indicate that the chitin layer is a chitin-protein complex.Experiments on the permeability of eggs of M. javanica at different temperatures indicate that changes in permeability are not due to the melting of a single lipid with a distinct melting point as had been thought in the past. We have found that Arrhenius activation energies calculated from the two slopes of an Arrhenius plot were 17·8 kcal/mol and 43·0 kcal/mol respectively, the transition from one to the other taking place at 62°C. We think that these changes are due to changes in the properties of lipoprotein membranes in the lipid layer. These membranes appear to be of paramount importance in controlling the permeability of the nematode egg shell.

The distribution of lipids and glycogen in some female oxyuroids

Parasitology ◽  
1964 ◽  
Vol 54 (3) ◽  
pp. 555-566 ◽  
Author(s):  
A. O. Anya
Keyword(s):  
Enterobius Vermicularis ◽  
Syphacia Obvelata ◽  
Egg Shell ◽  
Aspiculuris Tetraptera

1. The distribution of glycogen and lipids in three oxyuroids (Aspiculuris tetraptera, Enterobius vermicularis and Syphacia obvelata) is described and found to be similar to that in ascarids and other oxyuroids.2. Evidence is presented for the presence of both polysaccharides (possibly glycogen) and lipids in the cuticle.3. It is suggested that the chitinous layer of the egg-shell of A. tetraptera contains phospholipids in association with proteins.4. The distribution of phospholipids is described and it is suggested that their role is mainly structural.I am grateful to Dr P. Tate for advice and encouragement and to Dr D. L. Lee for much useful discussion and advice.

NOTES ON CERTAIN BUTTERFLIES, THEIR HABITS, ETC

1882 ◽  
Vol 14 (3) ◽  
pp. 49-56
Author(s):  
W. H. Edwards
Keyword(s):  
New Born ◽  
Egg Shells ◽  
Egg Shell ◽  
The Way

8. On Young Caterpillars Eating their Egg Shells.Mr. Scudder, Butterflies, p. 101, says, after describing the way in which the caterpillar eats out of the egg: “The taste he has gained of egg-shell seems to allure him; for, strange as it may seem, although placed by the provident parent within immediate reach of choice and succulent food, he will not taste it until he has devoured the last remmant of his prison-walls. Strange food this for a new born babe! The act, however, is plainly a provision of nature by which the tender animal is rid of a sure token to his enemies of his immediate proximity.” Surely here is an error in fact, and a wrong conclusion whatever the fact may be. I read the above statement on the 25th July last, and at once went to my garden to search for eggs of Libythea Bachmanni, on Hackberry leaves. The young caterpillars of this species are green, of a shade so near that of the leaves they feed on, that it is very difficult to discover them. Even where the tip of the leaf has been eaten, and their presence is suspected, it is easy to overlook them. I found at once three eggs and one young caterpillar. The egg from which this caterpillar had come was present at the base of the leaf on the extreme tip of which the little creature rested. A hole was in its side near the top, and no more had been eaten than just enough to permit egress.

Water Uptake and Embryonic Development in Eggs of Chorthippus Brunneus Thunberg (Saltatoria: Acrididae)

1969 ◽  
Vol 50 (2) ◽  
pp. 327-333
Author(s):  
F. MORIARTY
Keyword(s):  
Sodium Chloride ◽  
Embryonic Development ◽  
Water Absorption ◽  
Osmotic Pressure ◽  
Water Uptake ◽  
Water Loss ◽  
Chloride Solutions ◽  
Sodium Chloride Solutions ◽  
Close Relationship ◽  
Further Development

1. The pattern of water absorption by eggs of Chorthippus brunneus varies greatly between individuals. 2. The time at which water is absorbed does not have a close relationship with the stage of embryonic development. 3. Water absorption is not essential for prediapause development. 4. Eggs can only undergo blastokinesis and further development, after diapause is broken, if some water has been absorbed. 5. The rate of water loss or gain varies with the osmotic pressure of sodium chloride solutions. 6. Eggs which have started to absorb water appear to become desiccated more rapidly than eggs which have not.

Effective eradication of pinworms (Syphacia obvelata and Aspiculuris tetraptera) with Polygonum cognatum Meissn

2019 ◽  
Vol 196 ◽  
pp. 63-67 ◽  
Author(s):  
Fatma Tuğçe Gürağaç Dereli ◽  
Mert Ilhan ◽  
Esma Kozan ◽  
Esra Küpeli Akkol
Keyword(s):  
Syphacia Obvelata ◽  
Aspiculuris Tetraptera
Sign in / Sign up

Export Citation Format

Share Document