Cuticle Weight Research Articles

Female ixodid ticks grow endocuticle during the rapid phase of engorgement

Lees (Proc Zool Soc Lond 121:759-772, 1952) concluded that the ixodid tick Ixodes ricinus grows endocuticle during the slow but not during the rapid, phase of engorgement, a conclusion supported by Andersen and Roepstorff (Insect Biochem Mol Biol 35:1181-1188, 2005) for the same species. In this study analysis of dimensional data and cuticle weight measurements from female ixodid ticks (Amblyomma hebraeum) were used to test this hypothesis. Both approaches showed that endocuticle growth continues during the rapid phase, tapering to zero at a fed/unfed weight ratio of ~60. Of the total mass of cuticle in the engorged tick 32-43% was formed during the rapid phase. We demonstrate that if cuticle growth stopped at the end of the slow phase, there would not be sufficient cuticle to account for the thickness of cuticle observed at the end of engorgement. This finding is consistent with prior studies of Rhipicephalus (Boophilus) microplus, and with a dimensional analysis of the cuticle thickness data of Lees for I. ricinus, in contradiction to his conclusion from an analysis of tick cuticle weight measurements. An examination of cuticle weight measurements for I. ricinus by Andersen and Roepstorff similarly supports the finding of cuticle growth during the rapid phase. All ixodid ticks undergo major body expansion, typically tenfold or more, during a rapid phase of engorgement and require sufficient cuticle at the end of that process to contain their body. The fact that cuticle grows during the rapid phase of engorgement in three species suggests that this is a general characteristic of the family Ixodidae.

Cuticular penetration characteristics of urea in citrus leaves

SummaryRecent interest in reducing nitrate levels in ground water has stimulated a re-examination of the potential use of foliar applications of urea on citrus trees. We examined the penetration characteristics of urea through isolated cuticles in relation to their thickness and surface wax content in citrus (Citrus paradisi Macf.) leaves using a finite dose-diffusion system. Isolated cuticles with the greatest integrity were mounted on diffusion half-cells with the inner morphological surface in contact with citrate buffer solution.14 C-urea in citrate buffer was applied to the outer wax-rich morphological surface and the penetration of urea was monitored by repeated sampling of the receiver solution. Urea penetration through cuticles exhibited an asymptotic curve characterised by an initial lag phase of about 10 min, a quasi-linear phase of maximum penetration rate, averaging 2% of the urea applied h–1, occurred about 40 min after urea application, followed by a plateau phase during which the rate of penetration approached zero at 144 h. Total urea penetration averaged approx. 35% and tended to decrease with increased cuticle weight until the cuticles were 6 months-old. Re-hydration of the urea deposit, with water, stimulated additional penetration of about 1%; however, this was not significant. Epicuticular wax occurred as platelets that increased with leaf age. Dewaxing the cuticles significantly enhanced the maximum penetration rates by 30% of the amount applied h–1 and increased total penetration by 64%. This study provides valuable details on the transport of urea through isolated cuticles which is important in fine-tuning foliar urea fertilisation in citrus trees.

Water sorption-desorption in conifer cuticles: The role of lignin.

Current information on the type and amount of biopolymers present in the epidermis of conifer species is still insufficient. This work presents the detailed morphology and chemical composition of Araucaria bidwillii cuticle after selective treatments to remove the different types of biopolymers. After removal of the waxes, cutin and polar hydrolyzable components, a lignin-like fraction, which makes up 25% of the initial cuticle weight, was identified by GC-MS and infrared spectroscopy. The isolated lignin is of G type, mainly formed by guaiacyl units. This composition indicates that the conifer cuticle investigated here has similar composition to other conifer-isolated cuticles. Water sorption and desorption by the isolated cuticle and the different cuticle fractions, including lignin, were studied. The analysis of the isotherms, following distinct physicochemical models, gave useful information on the structural and physiological role of the different biopolymers present in the cuticle. Lignin fraction showed both a high water sorption and capability of retaining it in comparision to other cuticle components. Hysteresis effect on water sorption-desorption cycle and water cluster formations has also been studied, and their physiological role discussed.

Air Temperature, Humidity, and Leaf Age Affect Penetration of Urea Through Grapefruit Leaf Cuticles

Effects of air temperature, relative humidity (RH), and leaf age on penetration of urea through isolated leaf cuticles of `Marsh' grapefruit (Citrus×paradisi Macfad.) trees on `Carrizo' citrange (C. sinensis L. Osbeck × Poncirus trifoliata (L.) Raf. rootstock were examined. Intact cuticles were obtained from adaxial surfaces of `Marsh' grapefruit leaves of various ages. A finite dose diffusion system was used to follow movement of 14C-labeled urea from urea solution droplets across cuticles throughout a 4-day period. Within the first 4 to 6 hours after urea application, the rate of urea penetration increased as temperature increased from 19 to 28 °C, but there was no further increase at 38 °C. Increasing relative humidity increased urea penetration at 28 °C and 38 °C. Cuticle thickness, cuticle weight per area, and the contact angle of urea solution droplets increased as leaves aged. Cuticular permeability to urea decreased as leaf age increased from 3 to 7 weeks, but permeability increased in cuticles from leaves older than 9 weeks. Contact angles decreased with increased urea solution concentration on leaf surfaces that were 6 to 7 weeks old, but solution concentration had no effect on contact angle on cuticles from younger and older leaves. Changing urea solution pH from 8.0 to 4.0 could have an effect on the amount of urea penetrating the cuticle through the loss of urea from breakdown possibly due to hydrolysis. Results from this study define leaf age, environmental conditions, and formulation for maximum uptake of foliar-applied urea.

Treating Cotton with Cellulases and Pectinases: Effects on Cuticle and Fiber Properties

Cellulases and pectinases are used to treat raw cotton fibers and unscoured cotton fabrics. The structural changes in the surfaces of cotton caused by the enzymatic treat ments and resulting properties are the main focus of this study. Both staining tests and microscopy observations confirm that the cuticle is removed by the pectinases and cellulases. All evidence of fiber weight loss and fabric water absorbency shows that significant changes in cotton fiber and fabric properties occur with mild treatment conditions. Physical changes in the cotton surfaces are clearly revealed by scanning electron micrographs. All fiber weight loss values stemming from the enzymatic treat ments are smaller than or near the cotton cuticle weight. Sufficient water absorbency for textile processing is obtained with mild enzymatic treatments, corresponding to a small but statistically significant fiber weight loss.

Relations between glasshouse climate and dry weight of petals, epicuticular wax, cuticle, pre-harvest flowering period and susceptibility toBotrytis cinerea of gerbera and rose flowers

Studies were conducted on the effects of seasonal levels of relative humidity, temperature, and total radiation, on dry weight of petals, on fresh weight of epicuticular wax and of cuticle of petals, on numbers ofBotrytis cinerea lesions in petals, and on preharvest flowering periods in gerbera and rose. No temporal relationships or significant correlations were found among dry weight of petals, weight of wax and cuticle of petals, and numbers of lesions on the petals. Temperature, relative humidity and total radiation did not correlate significantly with dry weight of petals, or with fresh weights of wax and cuticle of petals, except for a positive correlation between relative humidity and cuticle weight in the gerbera cultivar Delphi. No relation was found between weight of epicuticular wax and cuticle of petals and susceptibility of gerbera and rose petals toB. cinerea. The thickness of wax and cuticle on flowers did not seem to be an important factor influencing the susceptibility of flowers toB. cinerea. The seasonal pattern in number of lesions produced on the flowers byB. cinerea was related to the effects of relative humidity and radiation on infectivity of conidia of the pathogen on the flower surface but not to the effects on the susceptibility of flowers.

Degradation of cuticle during larval‐pupal and pupal‐adult development of the housefly, Musca domestica

Abstract. The patterns of changes in cuticle weight, its chitin content and chitinase activity have been studied during postembryonic development of the housefly, Musca domestica L. During pupariation the larval cuticle loses weight. During the early part of this weight‐loss the decline in chitin content parallels the overall change in cuticle weight. A simultaneous elevation in chitinase activity suggests that at this time the larval cuticle is being enzymatically degraded. Later weight loss may be due to sclerotization. No significant changes in cuticle weight or its chitin content occur in pharate cuticle until one day before eclosion. However, a peak of chitinase activity found at mid‐late pupal stage suggests the timing of pupal cuticle breakdown.

Relationships between Postharvest Water Loss and Physical Properties of Pepper Fruit (Capsicum annuum L.)

Physical characteristics [initial water content, surface area, surface area: volume (SA: V) ratio, cuticle weight, epicuticular wax content, and surface morphology] were examined to determine relationships between physical properties and water-loss `rate in pepper fruits. `Keystone', `NuMex R Naky', and `Santa Fe Grande' peppers, differing in physical characteristics, were stored at 8, 14, or 20C. Water-loss rate increased linearly with storage time at each temperature and was different for each cultivar. Water-loss rate was positively correlated with initial water content at 14 and 20C, SA: V ratio at all temperatures, and cuticle thickness at 14 and 20C. Water-loss rate was negatively correlated with surface area and epicuticular wax content at all temperatures. Stomata were absent on the fruit surface, and epicuticular wax was amorphous for each cultivar.

Drought Response of Low and High Maintenance Landscape Roses

Abstract Acclimation to drought was studied in the low-maintenance (Rosa hybrida) ‘Ferdy’ and ‘Pink Meidiland’, and the high-maintenance ‘Double Delight’ and ‘Paradise’. All plants were acclimated to drought with five consecutive, 4-day drought cycles, followed by a 2-day irrigation recovery period after the fifth drought cycle. Low-maintenance cultivars experienced less drought stress, as evidenced by higher leaf water potential, whole plant transpiration rate (E), relative water content, and leaf conductance on the final day of drought stress cycles. Morphologically, the low-maintenance cultivars had greater leaf cuticle weight than high-maintenance cultivars. Differences in the density and size of stomata and epidermal cells were not related to drought response. Low-maintenance cultivars had a smaller evaporative surface (smaller total leaf areas, smaller individual leaves, and reduced shoot dry weights). However, root : shoot ratios (root dry weight : top dry weight) and leaf area ratios (total leaf area : total plant dry weight) were comparable. Drought acclimation caused a greater reduction in osmotic potential of low-maintenance roses during the recovery period. Apparently, drought resistance in the low-maintenance roses was associated with increased cuticle thickness, reduced evaporative surface, and smaller individual leaves.

Cuticle, shell porosity and water uptake through hens’ eggshells

Abstract 1. There was no correlation between water uptake by a warm egg (37 °C) immersed in iced water and the shell's porosity as measured by water vapour conductance.2. Eggs lacking cuticle on the shell took up more water than those having cuticle. There was no correlation between water uptake and the water vapour conductance of cuticle‐less eggshells.3. In general there was no correlation between the amount of water taken up by an egg and the weight of cuticle on its shell. With some eggs there was an association between water uptake and the extent of fissuring of the cuticle.4. It is postulated that the pore canals impede water flow such that osmotic forces acting across the shell membranes do not influence water uptake by eggs.

Physiological conditions and variations of body constituents during the moulting cycle of the spider Tegenaria atrica C. L. Koch (agelenidae)

1. Tegenaria atrica (♀ + ♂) moult 9 times to reach maturity. Two days before, a “legstriping” points to the ecdysis. 2. In the premoult stage lipids, carbohydrates, and water are high, proteins and cuticle weight are low. Immediately after ecdysis, high molecular carbohydrates decrease, amino acids increase. Within a period of 1–3 weeks after ecdysis, all organic constituents turn to the basic summer levels. 3. Changes of individual amino acids but not fatty acids are closely related to the moult, especially the tyrosine content drops sharply due to cuticle synthesis. 4. The metabolic rate is at least doubled during the foodless time prior to and after ecdysis.

The accumulation and utilization of food reserves by the adult female cattle tick, Boophilus microplus (Canestrini)

Changes in water content and cuticle weight during adult parasitic life of B. microplus, and the manner in which water and dry matter are utilized for egg production, suggest that capacity for cuticle growth, and thus for distension, determines water content in relation to body weight, and this in turn fecundity of the female. Figures for Australian B. microplus are compared with those for this species in Japan, where higher average engorged weight, cuticle weight, percentage water content, and numbers of eggs laid have been reported.

The chemical composition of wool. XI. Separation and analysis of exocuticle and endocuticle.

Whole cuticle is separated from wool by treatment in formic acid. Digestion of cuticle with pronase is complete after 36% by weight of cuticle is dissolved and the residue is shown by electron microscopy to be exocuticle, with no evidence of adhering endocuticle. The digested protein corresponds to endocuticle and the residue to exocuticle. The endocuticle contains only 3 residues per 100 of !cystine and is generally similar in amino acid analysis to the non-keratinous material from the cortex (Peters and Bradbury 1972).

The structure of insect cuticles.

The amount of chitin and of protein in the blowfly larval cuticle remains essentially unchanged during the process of hardening and darkening of the puparium. In the formation of the puparium there is a gain of weight of about 6 % over the larval cuticle weight, and this can be accounted for by the incorporation of phenolic substances. These are derived from the free tyrosine in the blood which decreases by an amount sufficient to account for the weight increase of the cuticle. An insoluble and highly resistant fraction has been isolated from the puparium, and this consists of about equal quantities of protein and pigment and possibly represents the natural association of these two substances in parts of the puparium. All the evidence suggests that the tyrosine is deaminated before giving the derivatives which combine with the cuticle substance, hardening and darkening it. Further properties of arthropodin, the water-soluble protein of soft arthropodal cuticles, are described. X-ray and related studies give a picture of the polysaccharide/protein complex in the cuticle which implies a model with alternating monolayers of protein and chitin. This appears to be based on a ratio of 3 amino acid residues to 1 chitobiose residue, or for equal lengths of protein and chitin chains a weight ratio of 45:55. This basic weight-ratio of protein and chitin appears to occur in the soft cuticles of blowfly larvae and other arthropods. A review is given of the composition and properties of various cuticles, and it is evident that hardening may be achieved without darkening of the cuticle. The chemical basis of this type of cuticle stabilization merits further study.