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 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.

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 tylenchid (Nematoda) egg shell: formation of the egg shell in Meloidogyne javanica

Parasitology ◽  
1976 ◽  
Vol 72 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Michael A. McClure ◽  
A. F. Bird
Keyword(s):  
Endoplasmic Reticulum ◽  
Meloidogyne Javanica ◽  
Distal Portion ◽  
Shell Formation ◽  
Lipid Layer ◽  
Dense Cytoplasm ◽  
Cytoplasmic Bridges ◽  
Pass Through ◽  
Egg Shell ◽  
Lipid Layers

SummaryOogonia of Meloidogyne javanica are radially arranged around a central rachis to which they are attached by cytoplasmic bridges. As the oocytes mature the rachis disappears and the oocytes pass through the oviduct in tandem. The oviduct-spermatotheca valve is constructed of two rows of tightly packed cells of which there are four per row. The nuclei of these cells are large and contain balloon-shaped cytoplasmic invaginations. The spermatotheca is characterized by microtubules which extend to its lumen and by invaginations of plasmalemma. Cells of the distal uterine region contain large intracytoplasmic spaces bordered by endoplasmic reticulum whereas proximal uterine cells have dense cytoplasm and large areas of compact endoplasmic reticulum. Egg-shell formation begins in the spermatotheca with the modification of the oolemma to form the vitelline layer. The chitinous layer begins in the distal portion of the uterus and appears to originate from the egg. Proline-containing protein is incorporated into the chitinous and lipid layers as the egg passes through the mid-region of the uterus and formation of the lipid layer in this region completes egg development.

The structure and permeability of the shell and vitelline membrane of the egg of Fasciola hepatica

Parasitology ◽  
1967 ◽  
Vol 57 (1) ◽  
pp. 47-58 ◽  
Author(s):  
R. A. Wilson
Keyword(s):  
Small Molecules ◽  
Fasciola Hepatica ◽  
Hydrolysis Product ◽  
Vitelline Membrane ◽  
Membrane Complex ◽  
Phosphate Ions ◽  
Cross Linkage ◽  
Egg Shells ◽  
Egg Shell ◽  
Main Barrier

The egg shell of Fasciola was investigated by electron microscopy and found to consist of a fine reticulum of fibrils. No evidence for concentric lamellae was discovered.The amino acids of the shell were identified using chromatography and it was suggested that the original protein was of a simple fibrous type. An unidentified spot was thought to represent a hydrolysis product of the cross-linkage. The effect of sodium hypochlorite on the shell, was also studied.The ‘vitelline membrane’ of the fully developed egg was found to consist of a layer of peri-vitelline material beneath which were two closely opposed unit membranes. The origin of these layers was discussed.The permeability of the shell and vitelline membrane was studied using simple physical techniques and radiotracers. The shell was found to be freely permeable to small molecules. The vitelline membrane complex was thought to represent the main barrier to permeability but an uptake of phosphate ions amounting to 8% of total phosphate, was recorded. This may have been more apparent than real as most of the activity was probably associated with egg shells rather than contents.I would like to thank Professor O. W. Richards in whose department this work was carried out, Dr F. Call for supervision of the work and Professor B. G. Peters for his many helpful criticisms. Lastly, I am indebted to Miss M. Morris without whose expert assistance the electron microscope studies would not have been possible.

SINGLE STEP SINTERED CALCIUM PHOSPHATE FIBERS FROM AVIAN EGG SHELL

2013 ◽  
Vol 22 ◽  
pp. 305-312 ◽  
Author(s):  
PRABHASH DADHICH ◽  
BODHISATWA DAS ◽  
SANTANU DHARA
Keyword(s):  
Calcium Phosphate ◽  
Chitosan Solution ◽  
Single Step ◽  
Coagulation Bath ◽  
Physico Chemical ◽  
Significant Research ◽  
Different Temperatures ◽  
Egg Shells ◽  
Egg Shell ◽  
Avian Egg

Different forms of calcium-phosphate (Hydoxyapatite, α-TCP, β-TCP, CDHA) minerals are found to be major component of bone tissue. Development of calcium-phosphate (CaP) based fibrous microstructures is of significant research interest worldwide owing to its improved mechanical properties and higher interconnectivity. Here we represent a method for single step sintered wet-spun Fibers of calcium phosphate from avian egg shells for biomedical applications. Raw egg shell powder was mixed with chitosan solution and Phosphoric acid. The mixture is milled in a ball mill overnight and then filtered. The slurry was de-aired using 100 microliter 1-octanol per 100 ml of slurry as antifoaming and wet spun in coagulation bath. Fiber was dried overnight and sintered at different temperatures for microstructure and phase analysis. Both green and sintered Fibers were physico-chemical characterized by SEM, EDX, XRD, TGA, DSC, FTIR, and stereo-zoom microscopy. The fibers obtained in this procedure are found to have highly porous interconnected structures which can provide good cell adhesion and therefore can be used for bioactive scaffold making.

The tylenchid (Nematoda) egg shell: formation of the egg shell in Meloidogyne javanica

Parasitology ◽  
1976 ◽  
Vol 72 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Michael A. McClure ◽  
A. F. Bird
Keyword(s):  
Endoplasmic Reticulum ◽  
Meloidogyne Javanica ◽  
Distal Portion ◽  
Shell Formation ◽  
Lipid Layer ◽  
Dense Cytoplasm ◽  
Cytoplasmic Bridges ◽  
Pass Through ◽  
Egg Shell ◽  
Lipid Layers

Oogonia of Meloidogyne javanica are radially arranged around a central rachis to which they are attached by cytoplasmic bridges. As the oocytes mature the rachis disappears and the oocytes pass through the oviduct in tandem. The oviduct-spermatotheca valve is constructed of two rows of tightly packed cells of which there are four per row. The nuclei of these cells are large and contain balloon-shaped cytoplasmic invaginations. The spermatotheca is characterized by microtubules which extend to its lumen and by invaginations of plasmalemma. Cells of the distal uterine region contain large intracytoplasmic spaces bordered by endoplasmic reticulum whereas proximal uterine cells have dense cytoplasm and large areas of compact endoplasmic reticulum. Egg-shell formation begins in the spermatotheca with the modification of the oolemma to form the vitelline layer. The chitinous layer begins in the distal portion of the uterus and appears to originate from the egg. Proline-containing protein is incorporated into the chitinous and lipid layers as the egg passes through the mid-region of the uterus and formation of the lipid layer in this region completes egg development.

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.

The Impact of Heat Treatment on Pyrophyllite Structure and Acid-Soluble Properties

2011 ◽  
Vol 366 ◽  
pp. 326-329 ◽  
Author(s):  
Jun Jun Wu ◽  
Hai Feng Chen ◽  
Shi Jiang Zhao ◽  
Bin Li
Keyword(s):  
Heat Treatment ◽  
Thermal Activation ◽  
Acid Leaching ◽  
Basic Structure ◽  
Hydrochloric Acid Concentration ◽  
Activation Temperature ◽  
Different Temperatures ◽  
Ft Ir ◽  
Heat Activation ◽  
The Impact

This paper studied the influence of heat treatment on the pyrophyllite structure and acid-soluble properties of alumina. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by XRD, TG-DTA, FT-IR and quantitative analysis of Al2O3. The quantitative titration method studied the dissolve characteristics of the different heat treatment samples in different acid conditions, and then a numerical simulation was done. The results showed that at temperatures below 480 °C, the pyrophyllite did not change the basic structure. 480~700 °C dehydroxylation reaction occurred, and the structure water of pyrophyllite is removed, and then turned into partial pyrophyllite. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C, the dissolution amount of alumina was largest. These works could provide some theoretical basis for further application of pyrophyllite research.

Plant nematodes associated with fruit trees in northern Australia

1981 ◽  
Vol 21 (108) ◽  
pp. 129 ◽  
Author(s):  
MR Sauer
Keyword(s):  
Carica Papaya ◽  
Fruit Trees ◽  
Soil Samples ◽  
Parasitic Nematodes ◽  
Northern Australia ◽  
Radopholus Similis ◽  
Plant Parasitic Nematodes ◽  
Rotylenchulus Reniformis ◽  
Musa Sp ◽  
Tylenchulus Semipenetrans

Sixteen genera of plant parasitic nematodes were found in 64 soil samples taken around fruit trees of 20 different genera at Kununurra, Darwin, or Adelaide River. Hemicriconemoides cocophilus, Basirolaimus seinhorsti, Rotylenchulus reniformis, Helicotylenchus s p p., and Xiphinema s p p. were found in more than 25% of samples, and Meloidogyne spp.in 16%. Paratrichodorus minor and Rotylenchus incultus were common at Kununurra. Nematodes found in plant roots at Darwin included M. javanica and R. reniformis on Carica papaya, Radopholus similis on Musa sp., Scutellonema brachyurum on Spondias cytherea. Tylenchulus semipenetrans was found in Citrus sp. roots at Adelaide River. Helicotylenchus dihystera was found in roots of Annona spp. at both these places.

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