An Egg-Waxing Organ in Ticks

1948 ◽  
Vol s3-89 (7) ◽  
pp. 291-332
Author(s):  
A. D. LESS ◽  
J.W. L. BEAMENT
Keyword(s):  
Inorganic Ions ◽  
Follicle Cells ◽  
Shell Layer ◽  
Critical Temperatures ◽  
Inner Membrane ◽  
Humid Atmosphere ◽  
Yellow Grease ◽  
Accessory Glands ◽  
Pore Canals ◽  
Natural Wax

1. During the oviposition of ticks a glandular organ--the organ of Géné is everted and touches the egg. If it is prevented from everting most of the eggs shrivel rapidly; few hatch even in a humid atmosphere. 2. The waterproofing properties of the normal egg are conferred by a superficial coating of wax, 0.5-2.0 µ. in thickness. In Ornithodorus moubata the wax is secreted and applied solely by Géné's organ. In Ixodes ricinus waterproofing takes place in two stages: an incomplete covering of wax, probably secreted by the lobed accessory glands, is first smeared over the egg during its passage down the vagina; waterproofing is then completed by a further application of wax from Géné's organ after the egg has been laid. Owing to its superficial position on the egg the wax layer is readily attacked by solvents and emulsifiers. 3. The morphology of Géné's organ in O. moubata is described. The gland is a proliferation of the epidermis which lies detached from the cuticle. Its secretion, a watery refractile liquid containing the wax precursor, accumulates between the gland and the cuticle in two horn-like extensions. The wax is probably secreted through pore canals distributed over a narrow zone of cuticle below the horns; the cement covering-layer of the epicuticle does not extend to this zone. 4. The transparent, heat-stable material isolated from the horns of Géné's organ is regarded as the wax precursor. Solubility in water is probably con ferred by chemical linkage with protein. The precursor is taken up from the horns, where it is stored, and is presumably broken down within the gland cells. The wax is then secreted through the pore canals while the protein moiety is retained by the cell. 5. The critical temperatures of the eggs of Ixodidae range from 35° C. in I. ricinus to 44° C. in Hyalomma savignyi; only slightly higher critical temperatures were recorded for Argasidae (45° C. in O. moubata). Eggs with lower critical temperatures are more susceptible to desiccation. The susceptibility of the eggs of a given species is of the same order as that of the parent species; but whereas in Ixodidae the critical temperatures of the egg and the cuticle of the female tick are approximately the same, in Argasidae the critical temperatures of the cuticle are much higher (62° C. in O. moubata). These differences are related to the physical properties of the waxes. The cuticular wax in O. moubata is hard and crystalline (m.p. 65° C), whereas the egg wax is soft and viscous (m.p. 50-54° C). 6. The natural wax from Géné's organ has definite powers of spreading on the surface of the egg and so completing the waterproofing layer. 7. The material extracted with boiling chloroform from egg-shells or from nymphal cuticles separates spontaneously into two fractions, a hard white wax (c. 85 per cent, by weight) and a soft yellow grease (c. 15 per cent.). The properties of these two lipoids differ conspicuously from those of the natural wax. Attempts to deposit the extracted materials on membranes in the form of a waterproofing layer were unsuccessful. 8. Ovulation is described in O. moubata. The shell of the tick egg is secreted by the oocyte itself and not by follicle cells. Three layers can be distinguished in the 24-hour egg: (i) an outer wax layer; (ii) an incomplete layer of granules which reduce ammoniacal silver nitrate; (iii) a shell layer. A fourth layer, the inner membrane (iv), is secreted by the oocyte after incubation for 2-3 days. 9. Both the shell layer and the inner membrane are composed of resistant, elastic protein and are devoid of chitin. The shell layer of the unwaterproofed egg is highly permeable to water and to large molecules with either hydrophilic or lipophilic affinities. The inner membrane is at first freely permeable to water and to inorganic ions. During the course of incubation the wax gradually migrates into the shell material and may reach the inner membrane. As this occurs, the effectiveness of abrasive dusts and of chloroform in promoting increased transpiration through the shell is notably reduced.

Memoirs: The Formation and Structure of the Chorion of the Egg in an Hemipteran, Rhodnius prolixus

1946 ◽  
Vol s2-87 (348) ◽  
pp. 393-439
Author(s):  
J. W. BEAMENT
Keyword(s):  
Average Diameter ◽  
Water Soluble ◽  
Follicle Cells ◽  
Protein Layer ◽  
Secretory Products ◽  
Large Water ◽  
Protein Components ◽  
Egg Shell ◽  
Pore Canals ◽  
Strong Acids

The main regions of the Ehodnius prolixus egg-shell have been defined; a concise definition has been obtained for the term ‘chorion’. The formation and structure of the unspecialized chorion has been followed from the time of differentiation of the follicle cells, up to the completion of the shell, and an assessment made of the chemistry and permeability of each component shell layer. The follicle cells are binucleate; changes in morphology and histology prior to secretion of the shell are outlined. The secretory products of the follicle cells fall naturally into an endochorion and an exochorion; the endochorion consists of five modifications of a proteinaceous substance. They are, in order of secretion: 1. The Inner Polyphenol Layer, which consists of a series of tanned granules of average diameter 2µ, containing large quantities of polyphenols. The layer is discontinuous and has no effect on permeability. 2. The Resistant Protein Layer, a tanned and possibly vulcanized layer of protein, 1 to 2µ, thick, containing diffuse polyphenols. It is resistant to strong acids and bases, and permeable to water, ions, and large water-soluble molecules. 3. The Outer Polyphenol Layer, which is similar to the inner layer, but has more minute granules. 4. The Amber Layer.--This is the only coloured layer of the shell, and is less than 0-1µthick. It consists of tanned protein to which oil is added after secretion. It is therefore a lipidized protein, which is excessively resistant to acids and alkalies, and permeable to oils and oil-soluble material and to small ions and water. 5. The Soft Protein Layer.--This is a thick laminated layer some 8µ. thick, similar to, but less resistant than, the resistant protein layer. It contains polyphenols and tyrosine. The layer is freely permeable to water-soluble substances. Throughout the secretion of the endochorion, the follicle cells stain deeply and appear to be filled with the protein components of the shell. The exochorion consists of two layers of the lipoprotein ‘chorionin’. 6. The Soft Exochorion Layer is a lipoprotein which is soluble in potash but not in strong acids; the layer is permeable to lipoid solvents and to water and small ions, but not to larger particles. It is 8µ thick at its maximum thickness, but contains follicular pits which, during secretion, are filled by long processes from the follicle cells. 7. The Eesistant Exochorion Layer is a more resistant form of chorionin. It lines the pits and covers the surface of the shell, giving rise to the polygonal markings corresponding to the follicle cells, each with a pit at its centre. The follicle cells contain quantities of lipoprotein during this phase of secretion, and are difficult to stain. A method of staining is described which shows that pore canals of two varieties are present in the exochorion layers only. They run from the walls of the pits but do not reach the endochorion. None of the layers of the chorion waterproofs the shell. In the rear end of the shell, the outer polyphenol layer is displaced towards the exochorion, thus increasing the resistant protein layer and reducing the soft protein layer. It is shown that all seven layers are present in the neck, and in the central region of the cap, and that the order of secretion is the same. Modifications are produced by variations in the thickness of the various layers. In the neck, the soft protein layer is reduced; in the cap, the resistant protein layer is reduced while the amber layer is 2µ thick, giving the cap a brown appearance. The soft protein layer is extremely thin and irregular while the exochorion layers are 16 µ thick. Pore canals are again present in two varieties. Some analysis is made of the formation of follicular pits; this appears to be correlated with the thickness of the exochorion and endochorion layers.

scholarly journals The Formation and Structure of the Micropylar Complex in the Egg-Shell of Rhodnius Prolixus Stähl. (Heteroptera Reduviidae)

1947 ◽  
Vol 23 (3-4) ◽  
pp. 213-233 ◽  
Author(s):  
J. W. L. BEAMENT
Keyword(s):  
Follicle Cell ◽  
Rhodnius Prolixus ◽  
Follicle Cells ◽  
Normal Order ◽  
Protein Layer ◽  
Complex Region ◽  
Phase Cycle ◽  
Secretory Products ◽  
Egg Shell ◽  
Pore Canals

An investigation has been made of the junction between the shell and cap in the egg-shell of Rhodnius prolixus. This complex region consists of the thickened rim of the cap connected by a thin sealing bar to the rim of the shell. The secretion of this part of the shell has been followed and compared with the formation of less specialized portions of the shell. The shell has been divided into units, each the product of an individual follicle cell. It has been found that all the seven layers which make up the unspecialized parts of the shell are present in the seal complex; that these consist of five endochorion layers and two exochorion layers in their normal order. The exochorion is secreted around long villi, one from each follicle cell. These give rise to follicular pits in the shell. In this complex region, cells start to secrete at various stages in the seven-phase cycle; their initial secretion is apparently related to the material with which they make contact at that time. After secretion has started, each cell completes the remainder of the cycle. The rim of the cap is the product of four rings of follicle cells; the additional thickness is achieved by an increase in the exochorion layers, secreted around a series of very long follicular pits. The sealing bar, which is produced by one ring of follicle cells, is composed of the inner four layers of the chorion only; the cells do not produce soft endochorion, or exochorion layers. At the cap end of the sealing bar there is the predetermined hatching line. It is apparently produced by the presence in the follicle of cells which are inactive during the secretion of the inner layers, and so prevent co-ordination between the active cells on either side. A weak point is also present at the base of the sealing bar, at the site of other inactive cells, though this fissure is not used at hatching. The rim of the shell is similarly produced by an expansion of the exochorion layers secreted around four rings of follicular villi. Of these, three rings of pits are filled in towards the end of secretion, but the fourth, lying on the upper portion of the rim, remains. These pits become the micropyles and associated structures. There are 200 pits in the completed rim, divided into two groups. About fifteen are micropyles; the remainder are cavities closed at each end, and to which the name ‘pseudomicropyle’ has been given. The pseudomicropyles are formed in a similar way to normal follicular pits, but start in the resistant protein layer, 0.5µ from the inside of the shell. They end in the resistant exochorion, where they are connected to the external surface by small bunches of pore canals. They probably play some part in the respiration of the embryo. The true micropyles form the only free path through the shell. The inner portion of each tube is lined with hydrophilic protein, and the outer portion, which lies slightly posterior to the pseudomicropyles, is composed of hydrophobic lipoprotein. The number of true micropyles is not constant, there being between ten and twenty scattered irregularly around the rim. However, eggs produced by older females contain fewer micropyles; this may account for a higher rate of sterility among these eggs. The cells which form the micropyles and pseudomicropyles are the only ones which do not adhere to the typical cycle of seven secretory products. But in omitting three phases, the attachment of the exochorion to a protein layer is retained. Evidence suggests that the cells forming the micropyles are determined in the earliest stages of secretion by being squeezed out of the pseudomicropylar ring of cells.

Transpiration and the Structure of the Epicuticle in Ticks

1947 ◽  
Vol 23 (3-4) ◽  
pp. 379-410 ◽  
Author(s):  
A. D. LEES
Keyword(s):  
Critical Temperature ◽  
Superficial Layer ◽  
Epidermal Cells ◽  
Ecological Niches ◽  
Moist Air ◽  
Critical Temperatures ◽  
Dermal Glands ◽  
Natural Choice ◽  
Pore Canals ◽  
Dual Mechanism

1. Ticks owe their impermeability primarily to a superficial layer of wax in the epicuticle. After exposure to increasing temperatures, water loss increases abruptly at a certain ‘critical temperature’. The critical temperature varies widely in different species, in Ixodidae ranging from 32 (Ixodes ricinus) to 45° C. (Hyalomma savignyi); and in Argasidae from 63 (Ornithodorus moubata) to 75° C. (O. savignyi). Species having higher critical temperatures are more resistant to desiccation at temperatures within the biological range. A broad correlation is possible between these powers of resistance and the natural choice of habitat. Argasidae infest dry, dusty situations whereas Ixodidae occupy a much wider variety of ‘ecological niches’. 2. If the tick cuticle is rubbed with abrasive dust, evaporation is enormously increased. Living ticks partially restore their impermeability in moist air by secreting wax from the pore canals on to the surface of the damaged cuticle. 3. Unfed ticks are able to take up water rapidly through the wax layer when exposed to high humidities. Water uptake, which is dependent on the secretory activities of the epidermal cells, is completely inhibited by the abrasion of only part of the total cuticle surface--a fact which suggests that the cells are functionally interconnected. Resistance to desiccation at low humidities is achieved by a dual mechanism: active secretion and the physical retention of water by the wax layer. 4. In Argasidae the epicuticle consists of four layers: the cuticulin, polyphenol, wax and outer cement layers. Only the three inner layers are present in Ixodidae. Since the wax layer is freely exposed in the latter group, chloroform and detergents have a marked action in increasing transpiration, particularly in those species with low critical temperatures. In Argasidae the cement layer is very resistant to extraction but is broken down by boiling chloroform. 5. The cuticulin, polyphenol and wax layers are all secreted by the epidermal cells. The waterproofing layer, which is deposited on the completed polyphenol layer, is secreted by the moulting tick relatively early in development and may be nearly complete by the time moulting fluid is abundant. In Ornithodorus moubata the cement is poured out by the dermal glands shortly after emergence. In Ixodidae the dermal glands undergo a complex cycle of growth and degeneration, but their products appear to add nothing of functional significance to the substance of the cuticle.

Studies on the egg of the horse bot-fly,Gasterophilus intestinalis(De Geer)

Parasitology ◽  
1961 ◽  
Vol 51 (3-4) ◽  
pp. 385-394 ◽  
Author(s):  
R. J. Tatchell
Keyword(s):  
Vitelline Membrane ◽  
Protein Layer ◽  
Inner Membrane ◽  
Free Air ◽  
Air Space ◽  
Bot Fly ◽  
Secondary Layer ◽  
The Subject ◽  
Pore Canals

1. A description is given of the egg ofGasterophilus intestinalis.2. The chorion has been shown to consist of a number of tanned protein and lipoprotein layers.3. The waterproofing of the egg is shown to be dependent on a primary wax layer on the inner membrane of the endochorion and a secondary layer on the vitelline membrane.4. The respiratory requirements of the egg are supplied from a free-air space between the inner membrane and the tanned protein layer of the endochorion which communicates with the atmosphere by specialized pore canals opening into the follicular grooves.Thanks are due to Dr P. Tate for suggesting the subject of this work and for his advice and encouragement during its progress.

scholarly journals Proteomic and Bioinformatic Profiling of Transporters in Higher Plant Mitochondria

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1190 ◽  
Author(s):  
Ian Max Møller ◽  
R. Shyama Prasad Rao ◽  
Yuexu Jiang ◽  
Jay J. Thelen ◽  
Dong Xu
Keyword(s):  
Plant Mitochondria ◽  
Inorganic Ions ◽  
Proteomic Profiling ◽  
Inner Mitochondrial Membrane ◽  
Higher Plant ◽  
Inner Membrane ◽  
Mitochondrial Carrier ◽  
Protein Uptake ◽  
Mitochondrial Carrier Family ◽  
Unexplored Area

To function as a metabolic hub, plant mitochondria have to exchange a wide variety of metabolic intermediates as well as inorganic ions with the cytosol. As identified by proteomic profiling or as predicted by MU-LOC, a newly developed bioinformatics tool, Arabidopsis thaliana mitochondria contain 128 or 143 different transporters, respectively. The largest group is the mitochondrial carrier family, which consists of symporters and antiporters catalyzing secondary active transport of organic acids, amino acids, and nucleotides across the inner mitochondrial membrane. An impressive 97% (58 out of 60) of all the known mitochondrial carrier family members in Arabidopsis have been experimentally identified in isolated mitochondria. In addition to many other secondary transporters, Arabidopsis mitochondria contain the ATP synthase transporters, the mitochondria protein translocase complexes (responsible for protein uptake across the outer and inner membrane), ATP-binding cassette (ABC) transporters, and a number of transporters and channels responsible for allowing water and inorganic ions to move across the inner membrane driven by their transmembrane electrochemical gradient. A few mitochondrial transporters are tissue-specific, development-specific, or stress-response specific, but this is a relatively unexplored area in proteomics that merits much more attention.

Rapid Critical Point Drying of Tissues in a Parr Bomb

1972 ◽  
Vol 30 ◽  
pp. 400-401
Author(s):  
C.A. Baechler ◽  
W. C. Pitchford ◽  
J. M. Riddle ◽  
C.B. Boyd ◽  
H. Kanagawa ◽  
...  
Keyword(s):  
Critical Point ◽  
Critical Pressure ◽  
Soft Tissues ◽  
Biological Tissues ◽  
Critical Temperatures ◽  
Air Drying ◽  
The Past ◽  
Critical Point Drying ◽  
Great Stress ◽  
Infiltration Techniques

Preservation of the topographic ultrastructure of soft biological tissues for examination by scanning electron microscopy has been accomplished in the past by using lengthy epoxy infiltration techniques, or dehydration in ethanol or acetone followed by air drying. Since the former technique requires several days of preparation and the latter technique subjects the tissues to great stress during the phase change encountered during air-drying, an alternate rapid, economical, and reliable method of surface structure preservation was developed. Turnbill and Philpott had used a fluorocarbon for the critical point drying of soft tissues and indicated the advantages of working with fluids having both moderately low critical pressures as well as low critical temperatures. Freon-116 (duPont) which has a critical temperature of 19. 7 C and a critical pressure of 432 psi was used in this study.

Scanning Tunneling Microscopy and Atomic Force Microscopy of Enzymes and Enzyme Complexes

1990 ◽  
Vol 48 (3) ◽  
pp. 174-175
Author(s):  
Ronald D. Edstrom ◽  
Xiuru Yang ◽  
Mary E. Gurnack ◽  
Marcia A. Miller ◽  
Rui Yang ◽  
...  
Keyword(s):  
Cell Biology ◽  
Inorganic Ions ◽  
Bulk Liquid ◽  
Soluble Form ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Metabolic Channeling ◽  
Simplistic Notion ◽  
Soluble Enzymes

Many of the questions in biochemistry and cell biology are concerned with the relationships of proteins and other macromolecules in complex arrays which are responsible for carrying out metabolic sequences. The simplistic notion that the enzymes we isolate in soluble form from the cytoplasm were also soluble in vivo is being replaced by the concept that these enzymes occur in organized systems within the cell. In this newer view, the cytoplasm is organized and the “soluble enzymes” are in fact fixed in the cellular space and the only soluble components of the cell are small metabolites, inorganic ions etc. Further support for the concept of metabolic organization is provided by the evidence of metabolic channeling. It has been shown that for some metabolic pathways, the intermediates are not in free diffusion equilibrium with the bulk liquid in the cell but are passed along, more or less directly, from one enzyme to the next.

IONIC EFFECTS ON THE UPTAKE OF CHLOROMERCURIBENZENE-p-SULPHONIC ACID BY PANCREATIC ISLETS

1977 ◽  
Vol 86 (3) ◽  
pp. 552-560 ◽  
Author(s):  
Monica Söderberg ◽  
Inge-Bert Täljedal
Keyword(s):  
Pancreatic Islets ◽  
Islet Cell ◽  
Choline Chloride ◽  
Inorganic Ions ◽  
Sulphonic Acid ◽  
Cell Uptake ◽  
Β Cells ◽  
Sulphydryl Groups ◽  
Microdissected Pancreatic Islets ◽  
Ionic Effects

ABSTRACT Effects of inorganic ions on the uptake of chloromercuribenzene-p-sulphonic acid (CMBS) were studied in microdissected pancreatic islets of non-inbred ob/ob-mice. Na2SO4 stimulated the total islet cell uptake of CMBS but decreased the amount of CMBS remaining in islets after brief washing with L-cysteine. CaCl2 stimulated both the total and the cysteine-non-displaceable uptake; the stimulatory effect of CaCl2 on the cysteine-non-displaceable CMBS uptake was counteracted by Na2SO4. NaCl, KCl or choline chloride had no significant effect on the total islet cell uptake of CMBS, whereas LiCl was stimulatory. It is concluded that β-cells resemble erythrocytes in having a permeation path for CMBS that is inhibited by SO42−. By analogy with existing models of the erythrocyte membrane, it is suggested that the SO42−-sensitive path leads to sulphydryl groups controlling monovalent cationic permeability in β-cells.

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