Upregulation of hemolymph and tissue ferritin by dietary HgCl2 in the wax moth Galleria mellonella

The effect of Hg treatment on hemolymph and tissue ferritin in the wax moth Galleria mellonella was examined by western blotting. At 48 h after feeding HgCl₂, the level of hemolymph ferritin increased approximately 1.8‐fold over that of control insects that were not fed HgCl₂, while there was a small increase in tissue ferritin. Time series experiments showed that tissue ferritin had a typically saturated pattern, with a maximum level from 24 to 72 h, although it decreased 12 h following HgCl₂ feeding, while hemolymph ferritin first decreased but subsequently increased. Tissue ferritin in the fat body, gut and Malpighian tubules, the main tissues of ferritin expression, was upregulated over time following treatment with Hg, and in particular, tissue ferritin in the gut increased by a large amount at 12–48 h. The results suggest that in G. mellonella, the ferritin‐inducible mechanisms following treatment with HgCl₂ are different for hemolymph and tissue ferritin, as are their biochemical properties.     

Wax Ester Production by the Marine Cryptomonad Chroomonas salina Grown Photoheterotrophically on Glycerol

SYNOPSIS. An age-autolyzed culture of Chroomonas salina , grown under cool-white light with glycerol, produced waxy lipid constituting about 44% of total matter harvested. This lipid was composed of 87% wax ester, 9% triglyceride, 3% polar lipid and 1% hydrocarbon. The major wax ester species were identified by total carbon number as C₂₆(28%), C₂₈(35%), C₃₀(15%). The main fatty acid components of the wax esters were 12:0 (39%), 14:0 (30%), 16:0 (14%), while the main alcohols were 14:0 (53%) and 16:0 (40%). The hydrocarbon fraction showed saturated paraffins ranging from C₁₇ to C₃₃, with odd-numbered chain components predominating. No polyunsaturated components were detected in the wax ester or hydrocarbon fractions. This is the first record of wax ester production by a cryptomonad or a marine phytoplankter.     

Intracuticular lipids of spinach leaves

The cuticular wax and cutin components of the cuticular membranes isolated from the leaves of two spinach cultivars have been determined. The membranes contain about 0·007 mg/cm² of cuticular wax which comprises monobasic acids (C₁₆–C₃₈) with hexadecanoic as the major component. The amounts of cutin are comparable with those of cuticular wax and the monomeric constituents are predominantly C₁₈ epoxy compounds. The most abundant monomer is 9,10-epoxy-18-hydroxyoctadecanoic acid (up to 63%) together with substantial amounts of 9,10,18-trihydroxyoctadecanoic acid (up to 22%). Also present are 9,10-epoxyoctadecane-1,18-dioic acid (6–7%) dihydroxyhexadecanoic acid (3–4%) and ω-hydroxymonobasic and fatty acid fractions. The tentative identification of two minor components, 18-hydroxyoxooctadecanoic and 9,10-epoxy-12,18-dihydroxyoctadecanoic acids, is also made. Although spinach membranes have a delicate structure their cutin composition is essentially similar to that of much more substantial membranes.     

Wax synthesis in Brassica oleracea as modified by trichloroacetic acid and glossy mutations

Two different mutations in Brassica oleracea, gl₅ and gl₄ have been re-investigated using acetate-1-¹⁴C labelling in an attempt to define more closely the nature of the genetic blocks to wax synthesis. It has been found that gl₅ is a mutation which blocks elongation in the Step C₂₈–C₃₀. The mutation gl₄ exhibits no elongation block and could be blocked in the decarboxylation Step C₃₀–C₂₉. 0·1 mM TCA supplied in the culture solution of cauliflower seedlings affected the leaf surface by producing a glossy appearance similar to that induced by gl₃ and gl₄. At this concentration growth was not inhibited and the appearance of the plants was normal except for the surface wax. The amount of surface wax produced was about 40% of that in untreated seedlings on a leaf area basis. Slight, but significant changes in wax composition were noted, mainly involving a reduction in C₃₀ acids and aldehydes, a slight reduction (33–29%) in alkane content, and a marked difference in chain length composition of the alkanes with C₂₇ increased relative to C₂₉. Over a range of concentrations from 0·1–1 mM, TCA inhibited incorporation of label from acetate-1-¹⁴C into C₃₀ acids and aldehydes more than into C₂₈ at concentrations 0·4–0·8 mM while label tended to accumulate in C₂₄ and C₂₆ acids; thus elongation C₂₈–C₃₀ was especially sensitive to TCA. TCA also inhibited incorporation into primary alcohols and esters almost as much as into C₂₉ compounds. In spite of relatively specific effects on incorporation of label into longer chain lengths, the resulting block to C₃₀ synthesis is not sufficient to make much difference to the overall rate of C₂₉ synthesis. Both results of analysis of wax from whole plants and experiments with tissue slices in vitro indicated that the effect of TCA in reducing the glaucousness of the leaf surface is a combination of overall reduction of wax synthesis together with slight but significant changes in wax composition.     

Composition of leaf surface waxes of Triticum species: Variation with age and tissue

The composition of cuticular wax from plants of spring wheat (varieties Selkirk and Manitou) and of durum wheat (variety Stewart 63) at various stages of growth, and of wax from different parts of the plants varies considerably. Wax was analysed, without preliminary separation, by GLC using Dexsil 300 as liquid phase. Alcohols are major components of wax from leaf blades and β-diketones are major components of wax from leaf sheaths, especially the flag leaf sheath. Glaucousness of the leaf sheath is due to the high β-diketone content. In the first 50 days after germination, before sheaths and flag leaf are completely developed, the major component is octacosanol (> 50%). At 66 days, when sheath development is complete, β-diketone content is greatest. Hydrocarbon composition differs for wax from leaf blade and leaf sheath and also for different leaf blades and between adaxial and abaxial sides of the flag leaf. From 66 to 100 days ester content of wax increases, especially in Selkirk wheat, apparently due to formation of wax containing high proportions of esters of trans-α,β-unsaturated C₂₂ and C₂₄ acids. The content of these acids in the free fatty acids and of diesters based on these acids also increases during this period.     

An avian equivalent of make-up?

We report that a long-distance migrating shorebird, the red knot, makes a complete switch from commonly occurring monoester preen waxes to a much rarer class of higher-molecular-weight diester waxes at the time of take-off to the high arctic breeding grounds. The cold arctic climate would have required a lowering of wax-viscosity, and thus, a shift in the reverse direction. We propose that a sexually selected need for a brilliant plumage has lead to this conter-intuitive temporary shift from monoesters to diester waxes. The difficulty of application of the diester preen waxes under cold conditions would ensure the reliability of the quality-signalling function of this most probably sexually selected trait.     

A Scanning Electron Microscopic Observations of the Leaves in Some Conifers

Scanning electron microscopic observations of the leaves in some conifers are described. These are hyplocheilie stomata surrounded by different morphological subsidiary cells. In Keteleeria, the lateral wall of larger subsidiary cells possesses prom.inant eutieular globoides. Cuticular semigloboides between the sinuoms epidermal anticlinal walls are most obvious in other epidermis. However the single laver of cushion cells which looated underneath the guard ceils of the abaxial epidermis in Cathaya is discovered. The mesophyll ceils with incurved walls of Cathaya consist mainly of single layer of flat oubical cells flat longi-cubieal cells as of the polytriehaeeous lamcllae, thus it may be designated as mesolamellae. It not only supports the establishment of Cathaya Chun and Kuang as a new genus of the Pinaeeae but also may be another important biosystematical evidence between Cathaya and Pinus. The distribution and polymorphism of foliar solereids in Amentotaxus which are different from leaves of other gymnosperms described. The transfusion tracheids are also different in some ways from other genera.     

Ongoing Growth Challenges Fruit Skin Integrity

As a result of continuing volume and hence surface-area growth, the skins of most fruit species suffer ongoing strain throughout development. Maintenance of surface integrity is essential to protect the underlying tissues from desiccation and pathogen attack. Fruit skins are commonly “primary” in structure. They comprise a polymeric cuticle overlying an epidermis and a hypodermis. The cuticle is responsible for the skin's barrier function and the cellular layers for the skin's load-bearing functions. Skin failure can be just of the cuticle layer (microcracking) resulting in barrier impairment or it can involve cuticle and cellular layers (macrocracking) resulting in both barrier and structural impairment. Fruit skin failure is associated with a number of disorders including shriveling, cracking, russeting, and skin spots. All result in reduced market value. Our objective is to review the literature on the strategies adopted by fruit to cope with the challenge of continuing skin expansion. We uncover a multistep strategy to prevent or minimize the risk of fruit skin failure. This comprises: (1) area expansion of the load-bearing skin-cell layer(s) by ongoing cell division and (2) the avoidance of skin stress or strain concentrations by matching patterns of skin-cell division to those of area expansion. Also involved, (3) are the partitioning of cuticle strain into plastic and viscoelastic components at the expense of the elastic one. For this, wax and cutin are deposited in the cuticle during growth. Wax and cutin deposition “fix” the strain in the cuticle. Cutin is preferentially deposited on the inner surface of the cuticle, which fixes the strain, but it leaves the outer cuticle surface more strained. Last, (4) if the primary skin is damaged, the barrier functions are restored by the formation of a “secondary” fruit surface (periderm). Lignin can also be used to strengthen the underlying cells following structural failure.     

Spruce budworm feeding and oviposition are stimulated by monoterpenes in white spruce epicuticular waxes

Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long‐range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short‐range host plant choice by both adult females and larvae of a folivorous forest pest (Choristoneura fumiferana). We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix (α‐pinene, β‐pinene, limonene, myrcene) and to white spruce (Picea glauca) epicuticular waxes in closed arenas. Ovipositing females preferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes + monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene‐treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax‐only discs, but showed no preference between extremely high monoterpene concentrations and wax‐only controls. In an insect‐free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg‐laying females and feeding larvae, and that their effects are synergistic.