Changes In Cuticle Research Articles

Ecdysis in scorpions: supine behavior and exuvial ultrastructure

Abstract. Ecdysis in scorpions has some common features in all species in which it has been examined. Immature scorpions about to molt become less active, and the cuticle changes in appearance. When humidity and other conditions are suitable, the animal begins ecdysis with cheliceral and pedipalpal movements and internal processes that tear the pleural membrane just ventral to the anterior and lateral edges of the carapace. The carapace is pushed upward from within, and the animal starts to emerge through the opening made by the elevated carapace. This is usually done in the prone position. As the anterior body emerges, the pedipalps and walking legs are stretched posteriorly with their distal ends temporarily confined within the old exoskeleton. The buthid scorpions Androctonus australis and Parabuthus transvaalicus become supine before they begin to emerge. Ecdysis is completed lying supine, and the animal rights itself shortly thereafter. A turnover from upright to supine is not seen at any other time in scorpions. After prone or supine extraction, the exuvium includes the cuticle of booklungs, bristles, and sensilla and is relatively intact except for the wedge‐shaped opening at the anterior end.

Developmental changes of cuticular constituents and their association with ethylene during fruit ripening in ‘Delicious’ apples

Abstract Developmental changes in total cuticle and cuticular constituents and their responses to ethylene during fruit ripening were studied using ‘Delicious’ apples. Total chloroform extractable wax and total cutin (including carbohydrate polymers) were 3.1 and 5.4 g m −2 , respectively, in young fruit. They increased during fruit development and reached 14.1 and 24.7 g m −2 of fruit peel, respectively, at harvest. During postharvest fruit ripening at 20°C, total cutin did not change but total wax increased to 21.5 g m −2 at 6 weeks. The increase of cuticular wax paralleled the increase of internal ethylene in fruit. Wax was separated by column chromatography into four portions — hydrocarbons and wax esters, free alcohols, free fatty acids, and diols. More than half of the diol fraction was ursolic acid. During fruit development, more hydrocarbons and diols than free fatty acids and alcohols accumulated in cuticle. During fruit ripening, all four portions increased, coinciding with the climacteric rise in ethylene, but rates of increase of free fatty acids and alcohols were higher than those of other portions. Preharvest treatment with 220 mg l −1 aminoethoxyvinylglycine (AVG) inhibited internal ethylene to −1 during 6 weeks at 20°C and no wax accumulation was detected in AVG-treated fruit. Preharvest treatment with 200 mg l −1 ethephon increased internal ethylene and accelerated wax accumulation compared with controls. Ethephon accelerated and AVG inhibited α-farnesene accumulation.

369 Relationship Between Ethylene Production and Accumulation of Cuticular Constituents in `Delicious' Apples During Fruit Ripening at Room Temperature

Developmental changes in total cuticle and cuticular constituents were studied with `Delicious' fruit. Total wax (0.31 mg/cm2) and total cutin (0.54 mg/cm2, including carbohydrate polymers) were low in young fruit. They increased during fruit growth and reached 1.41 and 2.47 mg/cm2 of fruit peel at harvest, respectively. During fruit ripening at 20 °C, total cutin did not change, but total wax increased rapidly and reached 2.15 mg•cm-2 at 6 weeks. The increase of cuticular wax paralleled the increase of internal ethylene in fruit. Wax was separated by column chromatograph into four portions, hydrocarbons and wax esters, free alcohols, free fatty acids, and diols. More than half of the diols was ursolic acid. During fruit development, more hydrocarbons and diols accumulated in cuticle than free fatty acids and alcohols. During fruit ripening, all of the four portions increased, coincident with the climacteric rise in ethylene, but the increase rates of free fatty acids and alcohols were higher than those of other portions. Aminoethoxyvinylglycine (AVG, 220 mg•L-1) preharvest treatment inhibited internal ethylene synthesis to below 0.5 μL•L-1 during 6 weeks at 20 °C, and also inhibited wax accumulation. Ethephon (200 mg/L) preharvest treatment increased ethylene production and accelerated wax accumulation. α-farnesene accumulation coincided with increased internal ethylene and paralleled free fatty acid and alcohol accumulation.

Micropropagation ofBetula uber (Ashe) Fernald

A method of propagation through nodal culture was developed for Virginia round-leaf birch,Betula uber (Ashe) Fernald. Nodal cultures of Virginia round-leaf birch had the greatest shoot elongation on woody plant medium supplemented with 7.5 μM benzyladenine and 2.9 μM gibberellin-3. Shoot elongation was significantly greater when benzyladenine was combined with gibberellin-3 than with benzyladenine alone. In conjunction with propagation, anatomical changes in cuticle and stomata were examined at different stages of culture. Changes in stomatal length, stomatal density, cuticle thickness, and palisade parenchyma layers were noted during the various stages of culture. Propagation through nodal culture provides a feasible method by which Virginia round-leaf birch can be propagated and maintained. The same techniques may be applicable to other endangered hardwood species.

Porous channels in the cuticle of the head-arrester system in dragon/damselflies (Insecta:Odonata).

The ultrastructure of the porous channels (PC) of the postcervical sclerite (SPC), which provides additional head fixation to the neck in adult odonates, was studied using TEM and high resolution SEM microscopy. Single chitin-protein microfibrils, about 0.14 micron thick, are arranged into channels with cylinder-like shapes. The axial rod of the chitin fiber (0.04 micron thick) is located in the center of the cylinder. The orientation of the axial rods was three-dimensionally demonstrated after dissolving the protein cover with NaOH. The PCs are arranged vertically to the surface and pass from the epidermal cells through all the cuticular layers to the surface of the cuticle. In the exo- and endocuticle, the PCs are usually oval in cross-section and about 0.3 micron thick. In the endocuticle, the cross-sectional area of the PCs varies widely, from 0.01-0.15 micron2. The shape of the PC is determined by the macromolecular organization of the chitin-protein microfibrils: the long axis of the channel is orientated parallel to the axis of the preferred orientation of the cuticular microfibrils. The microfibrils tend to follow the line of the channel very closely. In fractures orientated perpendicular to the surface, the PC resembles a ribbon-like construction, which was clearly demonstrated by casts. The strongly parallel orientation of PCs in the deep layers of the cuticle changes within the microtrichia (MT), and they begin to be curved. Numerous PCs pass through the microtrichium, and most of them end on its side wall. PCs usually contain channel filaments about 0.09 micron thick. Usually, a single channel contained one filament, but channels located in the deep layers of the endocuticle have from one to five single filaments. The filaments were observed in the intact cuticle and in the cuticle enzymatically treated with chitinase, while in the cuticle treated with NaOH filaments were absent. The porous channel system of the odonate arrester is interpreted as a device transporting adhesive excretions from the epidermal cells to the cuticular surface.

Porous channels in the cuticle of the head‐arrester system in dragon/damselflies (Insecta: Odonata)

The ultrastructure of the porous channels (PC) of the postcervical sclerite (SPC), which provides additional head fixation to the neck in adult odonates, was studied using TEM and high resolution SEM microscopy. Single chitin-protein microfibrils, about 0.14 μm thick, are arranged into channels with cylinder-like shapes. The axial rod of the chitin fiber (0.04 μm thick) is located in the center of the cylinder. The orientation of the axial rods was three-dimensionally demonstrated after dissolving the protein cover with NaOH. The PCs are arranged vertically to the surface and pass from the epidermal cells through all the cuticular layers to the surface of the cuticle. In the exo- and endocuticle, the PCs are usually oval in cross-section and about 0.3 μm thick. In the endocuticle, the cross-sectional area of the PCs varies widely, from 0.01–0.15 μm2. The shape of the PC is determined by the macromolecular organization of the chitin-protein microfibrils: the long axis of the channel is orientated parallel to the axis of the preferred orientation of the cuticular microfibrils. The microfibrils tend to follow the line of the channel very closely. In fractures orientated perpendicular to the surface, the PC resembles a ribbon-like construction, which was clearly demonstrated by casts. The strongly parallel orientation of PCs in the deep layers of the cuticle changes within the microtrichia (MT), and they begin to be curved. Numerous PCs pass through the microtrichium, and most of them end on its side wall. PCs usually contain channel filaments about 0.09 μm thick. Usually, a single channel contained one filament, but channels located in the deep layers of the endocuticle have from one to five single filaments. The filaments were observed in the intact cuticle and in the cuticle enzymatically treated with chitinase, while in the cuticle treated with NaOH filaments were absent. The porous channel system of the odonate arrester is interpreted as a device transporting adhesive excretions from the epidermal cells to the cuticular surface. Microsc. Res. Tech. 37:583–591, 1997. © 1997 Wiley-Liss, Inc.

Changes in cuticle of scalp hair in mild acquired zinc deficiency: A study using scanning electron microscopy

We herein report a case of zinc deficiency in a 5-month-old Japanese girl. Red crusted papules were observed on the periorificial areas, feet, and buttocks. Although there was no hair loss, the zinc concentration in the infant's serum was 24μg/dl, which was increased by an oral zinc supplement. Scanning electron microscopic (SEM) obseryation revealed that the scalp hair had an irregularly shaped cuticle and was unusually small and thin in diameter. These changes occurred before the onset of cutaneous symptoms, and remained after the skin manifestations had disappeared. The hair cuticle pattern and hair thickness returned to normal 2 months after zinc administration, while the skin eruptions disappeared more rapidly. It is suggested that damage to scalp hair in patients with mild acquired zinc deficiency takes place before the appearance of skin eruptions and persists after its disappearance, and that recovery from damage to the scalp hair takes place more slowly than that from a skin eruption.

Egg handling and storage

The temperature and relative humidity of storage, as well as the gaseous environment, interact with the fertile egg over time during storage in such a way as to affect the success of incubation either negatively or positively. This interaction occurs both above and below the “physiological zero”, at which embryonic metabolism is minimal. This interaction below physiological zero implies that certain physical aspects of the egg must be affected by the environmental conditions. As the eggshell is a relatively fixed component, changes in albumen, shell membranes, cuticle, yolk, or embryo proper must account for these time- and environment-related effects. It is concluded that the major contributor is the albumen, as it is obviously the most dynamic component below physiological zero and is strategically positioned.

Rapid Analysis of Volatile Flavor Compounds in Horticultural Produce Using Solid-phase Microextraction and Gas Chromatography–Time-of-flight Mass Spectrometry

Aroma analysis of horticultural produce is an emerging field in which both flavor producing and malodorous compounds are detected from within a complex sample matrix. Qualitative and quantitative information is desired to monitor produce ripeness and provide quality control over processed products such as juices, preserves and canned products. Conventional analysis methods such as purge and trap and gas chromatography–mass spectrometry provide much of this information but are laborious and time consuming. Faster techniques are required when large numbers of samples are being analyzed and when rapid feedback to the produce harvester is required. Solid-phase microextraction (SPME) has recently been shown to significantly reduce the sampling times required by more conventional methods. The use of fast gas chromatographic techniques along with the recently commercialized time-of-flight mass spectrometer has also significantly reduced the separation and analysis times. We have combined SPME with gas chromatography–time-of-flight mass spectrometry as a rapid and quantitative tool for the analysis of flavor volatiles in apples and tomatoes. The sampling and analysis processes provide significant improvements to sample throughput, with analysis times taking only 2–6 minutes. The linear response of this system to butylacetate, ethyl-2-methylbutanoate and hexylacetate ranges from ppb to ppm levels, and the identification of unknown flavor compounds is possible even in the presence of other co-eluting compounds. The SPME technique is able to investigate volatiles changes in apple cuticle and tissues, which open the new possibility for flavor biochemistry research.

Acid-rain-induced changes in cuticles and Ca distribution in Scots pine and Norway spruce seedlings

Seedlings of Scots pine (Pinussylvestris L.) and Norway spruce (Piceaabies (L.) Karst.) were subjected to acid rain irrigation at pH 7, pH 4, and pH 3 three times a week during the growing seasons of 1986–1989 in a field experiment. Scanning and transmission electron microscopy, energy dispersive spectrometry, contact angle measurements, and chloroform extraction of waxes were used to detect physicochemical changes in the needle cuticles. The first detectable symptoms of acid rain were observed after 5 weeks of acid rain treatment at pH 3 and pH 4, which resulted in few CaSO4 crystallites on visibly undamaged pine and spruce needle surfaces. After 7 weeks of acid rain treatment there were CaSO4 crystallites scattered over the whole needle surface area and erosion of the epicuticular waxes could be observed occasionally. CaSO4 crystal formation later decreased, especially on the needles of seedlings treated at pH 3. Ca concentrations in the needles and roots of the seedlings and in the soil in the boxes were higher in the pH 3 treatments than elsewhere. The more abundant deposition of Ca oxalate crystallites on the inner walls of the epidermal and hypodermal cells of the spruce needles than on their outer walls was probably also connected with Ca leaching, caused by acid rain. Acid rain also delayed wax synthesis, as 2-month-old pine needles exposed to pH 3 and pH 4 had about 50% less wax than the water controls in early August. The needle surfaces of the southern provenances of spruce and pine seedlings were slightly less wettable after pH 4 treatment than after the control water treatment, because they probably benefited from N and S compounds in the irrigation water. The needle surfaces were more wettable in the pH 3 and water control seedlings than in the other treatments.

Cuticle Differences during Ripening of Normal and rin Tomato Fruits

Ripening mutant gene rin (ripening inhibitor) in tomato inhibits, or greatly slows down, a wide range of processes related to ripening of the fruit, leading to a markedly extended shelf life. Although the use of films or coatings has been shown to retard ripening, the natural film that covers the fruit and delimits interchange with the environment, the cuticle, has not been well-characterized and related to ripening. The objective of this work was to characterize cuticle changes and establish their relationship with respiratory behavior. Turning tomato fruits with the gene rin, selection S-164 and normal tomato fruits were stored under marketing conditions (20C; 65% to 70% RH) to determine cuticular and physiological changes. Parameters evaluated were: cuticular weight changes (CW), permeability, soluble cuticular lipids (SCL), and epicuticular waxes (EW). In addition CO2 production was monitored every other day. Normal fruit increased in CW from 1.17 to 1.30 mg·/cm–2 and its EW from 11.49 to 24.49 μg·cm–2. On the other hand, rin tomatoes declined in CW and EW during storage. Both kind of fruits decreased their SCL content. Normal tomatoes exhibited the characteristic climacteric peak and showed an increase of cuticle permeability, while in rin tomatoes, these changes were not expressed.

Survival of the parasitoid Encarsia formosa after treatment of parasitized greenhouse whitefly larvae with fungal spores of Aschersonia aleyrodis

AbstractThe interaction between the entomopathogenic fungus Aschersonia aleyrodis and the parasitoid Encarsia formosa on greenhouse whitefly as a host organism was studied, in particular, the survival of the parasitoid after treatment of parasitized hosts with fungal spores. The mean number of parasitized black pupae per parasitoid produced at 25°C was significantly reduced after spore treatment in the first three days following parasitization. Spore treatment four, seven or ten days after parasitization resulted in a mean number of parasitized pupae not significantly different from the number of black pupae in the control. The rather sudden change from low to high survival of parasitized hosts when treated with spores four days after parasitization in spite of high numbers of infected unparasitized larvae, coincided with the hatching of the parasitoid larva from the egg inside the host. Possible reasons for this decrease in susceptibility to infection after parasitoid egg hatch, such as induced changes in host cuticle or haemolymph, are discussed. Parasitoids emerged from treated hosts did not show differences in reproduction compared with parasitoids emerging from untreated hosts. Both natural enemies of whitefly are compatible to a great extent.

930 PB 509 CHANGES IN CUTICLE CHARACTERISTICS DURING POSTHARVEST HANDLING OF BELL PEPPERS

Dehydration limits bell pepper postharvest life. Research had focused on waxes and individual sealed packages used to prolong shelf-life. Even though, the fruit natural package -the cuticle- is unknown; besides, cuticle functions as a barrier to protect fruits against excessive water loss. The objective of this work was to characterize cuticle changes and their relationships with fruit quality during postharvest handling. Green `Wonder' bell peppers were stored under marketing conditions (20C; 65-70% RH). Following cuticle isolation determinations included weight changes (CW), permeability and soluble cuticular lipids (SCL). In addition, quality characteristics like firmness, total soluble solids (TSS), titratable acidity (TA) and CO2 production were monitored every other day. CW and SCL decreased from 2798 to 1398 and 145 to 48 μg/cm2, respectively. Permeability was also reduced from 11 to 10 mg/cm2*h. CO2 climateric was reached between the 9 and 12th day peaking with 25 mg/kg*h. Firmness decreased from 2.1 to 1.1 Kg*f, while no noticeable changes were observed on TSS and TA.

Activity of optical and geometrical isomers of the juvenile hormone analogue hydroprene on endogenous juvenile hormone levels in Larval Manduca sexta

AbstractThe geometrical and optical isomers of the insect juvenile hormone analogue hydroprene (ethyl (2E,4E)‐3,7,11‐trimethyldodeca‐2,4‐dienoate) were tested in vivo, both for ability to depress endogenous juvenile hormone titre and as juvenile hormone agents in larval Manduca sexta. The structure‐activity relationships of these isomers were found to be similar both for feedback inhibition of juvenile hormone levels, and for juvenile hormone activity as indicated by pigmentation changes in larval cuticle. In both cases, the (7S) (2E,4E) isomer was the most active of the materials tested.

Pathways of Calcium Penetration through Isolated Cuticles of ‘Golden Delicious’ Apple Fruit

Abstract Cuticles from ‘Golden Delicious’ apples (Malus domestica Borkh.) were isolated enzymatically. Changes in cuticles of developing fruit at various stages were studied using scanning electron (SEM) and light microscopy (LM). Structures allowing Ca penetration through the cuticle were studied by precipitating permeating Ca in agar as it passed through the cuticle. The importance of lenticels in the penetration of Ca at 2 stages of fruit development was studied under saturated conditions using a diffusion cell. The lenticels had a significant positive effect on Ca penetration. The development of a dense network of structures resembling cracks, as well as occasional surface discontinuities, were observed in cuticles isolated from fruit harvested in September. These structures seemed to provide pathways for cuticular Ca penetration. The importance of lenticels, cracks, or other surface irregularities, and the process of diffusion in the penetration of Ca into apple fruit is discussed.

Effects of Freezing, Thawing, and Cooking on the Appearance of Highbush Blueberries

Abstract Increases in the darkness and redness of both thawed and cooked highbush blueberries (Vaccinium corymbosum L.), indicated by tristimulus measurements, were cultivar-related but not dependent on blueberry pH or anthocyanin content. Waxy bloom was retained in thawed berries but lost during cooking. Pigmented exudate appeared with some cultivars during thawing. Differences among cultivars in exudate formation and reddening during thawing are explained in terms of changes in epidermal cells, cuticle, and wax structure which were observed by light and electron microscopy. The color of blueberry cooking water depended primarily on the berry anthocyanin content, acidity, and the extent of leaching.

Ultrastructural changes in intersegmental cuticle during rotation of the terminal abdominal segments in a mosquito

The terminal abdominal segments of male Aedes aegypti rotate 180° within 24 hr after adult emergence, rotation occurring in the intersegmental membrane between abdominal segments VII and VIII. The ultrastructure of this rotating membrane is compared with non-rotating intersegmental membranes at different developmental stages. The deposition of cuticle in both the rotating and non-rotating intersegments appears ultrastructurally similar, and follows the sequential pattern described for other insects. Shortly after adult emergence, however, disruptive changes occur in the membrane cuticle that are more pronounced in non-rotating intersegments. This disruption occurs initially 1 hr after adult emergence and becomes maximal within 3 hr. Disruption appears to occur by the addition of fluid to the cuticle and results in a ten-fold increase in cuticle thickness in non-rotating intersegments but only a two-fold increase in thickness in the rotating intersegment. While in the disrupted condition, the non-rotating intersegmental membranes become extensively folded whereas the cuticle in the rotating intersegment becomes stretched. During rotation, strain forces in the rotating intersegment result in a reorientation of microfibers in the cuticle from parabolic to parallel. This reorientation is presumably brought about by plastic flow.

Some ultrastructural changes in cuticle and hypodermis of Aporcelaimellus during the first moult (Nematoda: Dorylaimoidea)

The architecture of the body cuticle of juvenile Aporcelaimellus is identical to that of the adult, but the infracuticle is absent in the first stage juvenile. The cuticle is composed of fiber layers that are separated and perforated by a lacunar system. The lacunae are thought to contribute to the flexibility of the cuticle. The hypodermis is cellular. The cell-to-cell contacts consist of convoluted membranes that are often fortified by zonulae adhaerentes. The first moult was studied in specimens in the A1- and A5-stage (terminology of Coomans and van der Heiden, 1971). A stage chronologically prior to the A1-stage was found, which is referred to as A0-stage in this paper. During the A0-stage, the hypodermal cells become hypertrophic and gland-like. The zonulae adhaerentes seem to be replaced by septate desmosomes. The cuticle separates from the hypodermis. Cuticle-formation is in progress during the A1-stage. The outer layers of the new cuticle are laid down by the hypodermal cells underneath the old cuticle. Projections from the epithelium become enclosed within the new cuticle. Cuticle-secretion is completed during the A5-stage, but hardiy any differentiation is discernable. At the end of the A5-stage differentiation initiates by condensation of the filamentous material. The hypodermal projections gradually retract from the cuticle. It is concluded that the lacunar system originates from the differentiation-process. No evidence was found for partial resorption of the old cuticle.

Evidence for two mechanisms of sclerotisation in insect cuticle.

IN many insects the cuticle changes drastically in properties soon after a moult. When the insect emerges from the old cuticle the new one is soft, pale, and a major part of the proteins can easily be extracted. Gradually the proteins become insoluble, the cuticle becomes harder, and in many cases it also becomes darker. The colour may range from a very light amber to dark brown or even black. It has been discussed repeatedly whether hardening and darkening are two independent processes or whether they are two results of the same chemical reaction, but no definitive conclusions have been reached1–6.

An electron-microscope investigation into the cuticle and associated tissues of the operculum of some marine serpulids

The fine structure of the opercula of Spirobis borealis Daudin and S. pusilloides Bush, and the primary and secondary operculum of S. granulatus (L) have been examined by electron microscopy. In different regions, the epithelium of the operculum exhibits variations in thickness and fine structure which correspond to transitions from peduncular to opercular wall to opercular plate epithelia. Externally, the peduncle and walls of the operculum are covered by a cuticle which is composed of several layers of fibrils/fibres embedded in an amorphous matrix. It is regularly traversed by microvilli from underlying cells. At the operculum rim, the cuticle changes so that its appearance is thick and solid. It continues across the roof of the operculum as a thin layer overlying a calcareous plate. The secondary operculum of S. granulatus differs from those of the other species in that an internal calcareous plate and solid cuticle line the roof of the operculum. It differs further in possessing an opercular pore. The possibilities are discussed of the cuticle fibrils/fibres of the peduncle and the opercular wall being collagenous in nature, and later being transformed to a solid tanned structure overlying a calcareous plate. The modes of secretion of the cuticle and calcareous plate by underlying cells are also discussed.