SEM Observation of the Inner Surface Structure of Needle Cuticles in Pinus

Comparative investigation on the inner surfaces of needle cuticle of Pinus was made for 17 species and two varieties under SEM. It is shown that the differences in protrusions and depressions of the internal cuticle surfaces of needles in the genus are not remarkable. However, the features of intercellular flanges are rather distinct and three types can be distinguished. They are: (1) Subgen. Strobus (Sweet) Rehd (except Sect. Parrya) is of the Pinus koraiensis type; (2) Subgen. Pinus is of the P. tabulaeformis type; (3) Sect. Parrya Mayr of Subgen. Strobus (Sweet) Rehd is of the P. bungeana type. The character may provide taxonomy of the genus Pinus with a new piece of evidence. Based on the features mentioned above, together with many others, such as wood anatomy, warts of wood tracheids, bark structure, needle anatomy and cuticle structure as well as karyotypic analysis in Pinus, the author considers that division of Pinus into two subgeuera is natural and that separation of Sect. Parrya Mayr from Subgen. Strobus (Sweet) Rehd. and thesubsequent establishment of the subgenus Parrya of its own are also reasonable.     

The Role of Cuticular Strata Nomenclature in the Systematics of Nemata

A system of cuticular nomenclature based on the strata observed in Enoplia is proposed. Nematode cuticle is divided into four fundamental strata: epicuticle, exocuticle, mesocuticle, and endocuticle. Application of this system allows the correlation of complementary strata throughout Nemata. The major taxonomic categories within Nemata are differentiated on the basis of their cuticular strata as compared with the Enoplia model cuticle.     

The stabilization of locust cuticle

Cuticle from the metathoracic femur of adult locusts (Locusta migratoria) is characterized with respect to changes in water content and in protein extractability during maturation. The swelling behaviour and extractability of fully-sclerotized cuticle are compared to those of chemically-modified, unsclerotized cuticle.It is concluded that although dehydration may contribute to the stabilization of cuticle, it cannot account for the observed differences. The properties of mature cuticle can best be explained by the assumption that covalent cross-links are present between protein molecules.     

Trichome anatomy of the Saxifragaceae S. l.from the southern hemisphere

Trichome anatomy was examined by light and scanning electron microscopy in 25 genera of Engler's Saxifragaceae from the southern hemisphere. Four principal categories of trichome were recognized: (1) multiseriate with a glandular head; (2) uniseriate with a glandular head; (3) uniseriate, eglandular; (4) unicellular, eglandular. The shape of eglandular hairs ranges from erect to sickle-shaped to T-shaped. The main taxonomic conclusions are as follows: (a) Vahlia should be excluded from tribe Saxifrageae and a possible relationship with Montinia investigated; (b) Francoa and Tetilta (tribe Francoeae) are closely related, although the relationship of the tribe to its parent subfamily, Saxifragoideae, is unclear; (c) Eremosyne is probably allied to the Escallonioideae; (d) subfamily Brexioideae is heterogeneous in trichome anatomy, but the relationships of its constituent genera remain problematic; (e) subfamily Escallonioideae is heterogeneous in trichome anatomy, although similarities between and within the constituent tribes do exist. Thus Cuttsia and Abrophyllum form a natural group (tribe Cuttsieae), to which Carpodetus (tribe Argophylleae) may also be related; similarity in trichome anatomy between Argophyttum and Corokia (tribe Argophylleae) is substantiated by an extensive survey of all the species, and the data tentatively suggest a possible hydrangeoid affinity for these two genera.Forgesia (tribe Forgesieae) is shown to possess the same kind of hairs in the flowers as Quintinia (tribe Escallonieae), and Choristylis (tribe Forgesieae) is shown to be remarkably similar to Escallonia, prompting a suggestion that the two tribes be merged. Trichome data support the inclusion of Anopterus and Polyosma in their own tribes, although their wider affinities remain unclear. Doubts about the inclusion of the glabrous Tribeles in Escallonioideae are expressed. Our material of the following additional genera Lepuropetalon, Tetracarpaea and Brexia was glabrous and little comment could be made about them.     

Changes in the mechanical properties of the extensible cuticle of Rhodnius through the fifth larval instar

The ultimate tensile strength (σ_UT) and the modulus of elasticity (E) of Rhodnius extensible cuticle are σ_UT = 2.20 × 10⁷ Nm^?2, E = 2.43 × 10⁸ Nm^?2 (unplasticised); σ_UT = 1.43 × 10⁷ Nm^?2, E = 9.45 × 10⁶ Nm^?2 (plasticised with 5HT) and σ_UT = 9.05 × 10⁶ Nm, E = 2.46 × 10⁶ Nm^?2 (plasticised in pH 5 buffer).The mechanical properties of cuticle from insects which have deposited additional layers of cuticle after they have been fed differ from those of cuticle from unfed insects. This is possibly due to the different composition of the additional cuticle: it is suggested that the post-feeding cuticle is providing protection and a template for the next instars cuticle.The maximum strain of extensible cuticle from starved insects is related to the amount of matrix protein present.     

角质层的离析及显微观察方法

植物角质层的离析方法很多,获取化石植物的角质层可以同时用几种化学处理方法。舒氏液浸解是最常用的方法,也是几种方法共用时最关键的步骤。浸解液浓度过大或处理时间过长有可能破坏角质层的结构。对于已经获取到的角质层,利用相差光学显微技术可以增加反差。利用微分干涉光学显微技术不仅反差增加,而且有立体感,背景颜色也可以调节。荧光显微分析技术在不破坏标本的前提下,可以获取到表皮的特征。扫描电子显微镜具有观察不透明物体,放大范围广以及高的分辨力等优越性,可作为光学显微镜的必要补充。     

A freeze-fracture study of the surface of the infective-stage larva of the nematode Trichinella

The surface layers of the cuticle of the infective, first-stage larva of the nematodes Trichinella spiralis and T. spiralis var. pseudospiralis have been studied by means of the freeze-fracturing technique. No obvious differences between the two nematodes were found. A double-layered structure covers the cuticle. Its outermost layer consists of particles embedded in an amorphous matrix; its inner layer is composed of a sheet of fine filaments which may be composed of globular subunits. This unique double layered structure is not like a normal cell membrane in structure. The surface of the cuticle beneath it is relatively smooth except for impressions from the inner surface of the double-layered structure. The cuticle surface did not fracture in the manner of a cell membrane.     

Temperature dependence of the electrical resistance of hornet cuticle: A statistical model

The electric resistance to d.c. of the yellow strips in the cuticle of worker hornets was measured in the dark under temperature changes within the optimal range of activity outside the nest (10–32°C). A distinct inverse correlation was observed between the resistance and the temperature, the former decreasing with rise of the latter. In all, each individual hornet measured was subjected to four successive cycles of measurement during which the specimens underwent warming followed by cooling. A slight unidirectional rise in the resistance both during warming and cooling was observed between two successive cycles. A typical thermal hysteresis loop formed between the warming and cooling lines, thus suggesting a memory effect.     

Freeze-fracture studies on tardigrade cuticle

The cuticles of the heterotardigrade Echiniscus testudo and the eutardigrades Macrobiotus hufelandi and Milnesium tardigradum have been studied using freeze-fracture technique. Most of the layers seen in conventional TEM micrographs can be visualized. There is no clear evidence that the trilaminar components of the cuticle such as the outer epicuticle and the tripartite layer separating epi- and intracuticle or procuticle (whose membranous origin has been suggested by previous authors) fracture like a lipid bilayer. Microfibres not resolved or only poorly resolved by TEM can be recognized in the procuticle of all three species. Obviously their visualization depends upon the fracture angle. In Echiniscus testudo and Milnesium tardigradum the intracuticle or at least parts of it show a wavy arrangement of microfibres. Parts of the ventral intracuticle of E. testudo fracture in an obviously non-random pattern revealing distinct sublayers.     

Arabidopsis HSP70‐16 is required for flower opening under normal or mild heat stress temperatures

Sepals play important roles in protecting inner floral organs from various stresses and in guaranteeing timely flower opening. However, the exact role of sepals in coordinating interior and exterior signals remains elusive. In this study, we functionally characterized a heat shock protein gene, Arabidopsis HSP70‐16, in flower opening and mild heat stress response, using combined genetics with anatomic, physiological, chemical, and molecular analyses. We showed that HSP70‐16 is required for flower opening and mild heat response. Mutation of HSP70‐16 led to a significant reduction in seed setting rate under 22°C, which was more severe at 27°C. Mutation of HSP70‐16 also caused postgenital fusion at overlapping tips of two lateral sepals, leading to failed flower opening, abnormal floral organ formation, and impaired fertilization and seed setting. Chemical and anatomic analyses confirmed specific chemical and morphological changes of cuticle property in mutant lateral sepals, and qRT‐PCR data indicated that expression levels of different sets of cuticle regulatory and biosynthetic genes were altered in mutants grown at both 22°C and 27°C temperatures. This study provides a link between thermal and developmental perception signals and expands the understanding of the roles of sepal in plant development and heat response.     

Soluble cuticular phenoloxidase in the gypsy moth Lymantria dispar

The soluble enzyme phenoloxidase (tyrosinase) from the larval cuticle of Lymantria dispar has been partially purified using Ultrogel ACA 34, and the activity has been determined using phenolic substrates. The enzyme exhibited more activity toward O-diphenolic substrates and monophenolic substrates. The enzyme is inhibited by diethyl dithiocarbamate, phenylthiourea, and thiourea. The enzyme has been localized in the 7% slab and disc PAGE as an intense band. The enzyme is suggested to be involved in wound healing. © 1992 Wiley-Liss, Inc.     

Cytological location and further characterization of the Third chromosome resistance gene in Drosophila melanogaster

Mutations in the Third chromosome resistance (Tcr; 3-39.6) gene confer dominant resistance to α-methyl dopa and suggest the gene is involved in catecholamine metabolism. Evidence for involvement in catecholamine metabolism comes from the three phenotypes associated with the mutant Tcr chromosomes dominant resistance, dominant rescue of partially complementing l(2)amd alleles, and recessive lethal phenotypes. Only dominant resistance to αs-methyl dopa, however, was mapped to the Tcr locus. Both recessive lethality and dominant rescue of l(2)amd alleles have now been mapped to the Tcr gene and, through the isolation of a new deletion in the region, we demonstrate these phenotypes are due to a loss of Tcr function. This deletion places the Tcr gene in the 69B4-5 to 69C8-11 region. Additionally, we have tested and verified three predictions of the biochemical model proposed by Bishop, Sherald, and Wright (1989) for the function of the Tcr protein. This revised version was published online in July 2006 with corrections to the Cover Date.     

植物角质层蜡质的化学组成研究综述

角质层是植物与外界的第一接触面,而角质层蜡质则是由位于角质层外的外层蜡质和深嵌在角质层中的内层蜡质两部分构成。植物角质层蜡质成分极其复杂,具有重要的生理功能。综述了有关植物角质层蜡质的化学组成信息,探讨了目前植物角质层蜡质化学成分研究中存在的一些问题,展望了角质层蜡质成分的研究前景。     

Latent larval cuticular phenoloxidase in the coconut pest,Oryctes rhinoceros

Cuticular phenoloxidase (Tyrosinase) in the larval stage of the coconut pest Oryctes rhinoceros has been extracted in the stable proform using cane sugar saline/borate buffer. The extracted prophenol oxidase can be activated by the addition of proteolytic enzymes such as trypsin, chymotrypsin, thermolysin, and subtilisin. Detergents such as SDS and Tween-80 also activated the enzyme. Electrophoretical analysis revealed dissociation of the enzyme into two molecular forms after its activation by proteolytic enzymes. The functional significance of the enzyme is suggested to involve the generation of quinone compounds in the wound healing process: most phenoloxidase inhibitors prevented melanization when applied topically to surgical wounds. © 1996 Wiley-Liss, Inc.     

Future questions in insect chitin biology: A microreview

This microreview stems from the Second Symposium on Insect Molecular Toxicology and Chitin Metabolism held at Shanxi University in Taiyuan, China (June 27 to 30, 2017) at the institute for Applied Biology headed by Professor Enbo Ma and Professor Jianzhen Zhang.     

Cuticular reactivity of early larval stages of Ascaris suum: binding of fractions of immune serum to the surface of infective and parasitic stage larvae as detected by the mixed antiglobulin test.

Infective stage and early parasitic larvae of Ascaris suum were evaluated for surface reactivity with serum from uninfected and hyperimmune guinea-pigs. Cuticular binding of serum components was assessed by the mixed antiglobulin test.Ensheathed infective larvae bound both normal serum proteins and 7S protein from immune serum over the entire sheath surface. Parasitic larvae recovered at 16 and 25 h post infection (h.p.i.) were poorly reactive, and binding occurred only to sites on the head and tail regions. Larvae recovered at 48 and 72 h.p.i. were highly reactive over the entire cuticle.Host serum protein was not detectable on the surface of parasitic larvae when harvested from guineapigs after a primary infection until the larvae had been in the host for 72 h. However larvae recovered from hyperimmune animals had host serum protein detectable on the cuticle as early as 16 h.p.i.     

SEM Observation on the Structure of Cuticles on Leaf Inner Surface of Abies (Pinaceae) and Its Significance in Systematics

Comparative investigation of the inner surface of the needle cuticle of 36 species and 2 varieties of Abies under SEM has revealed that the characteristics of the intercellular flanges are rather distinct and four types can be distinguished: (1) Straight and developed single flange. This type is only represented by Abies bracteata D. Don. Morphologically, this species is also quite unique in the genus Abies and was once treated as a subgenus by Franco and Liu. Its special structure of the leaf cuticle observed here seems to support their treatment. (2) Double flanges. This type was first discovered in a leaf fossil of Abies from England. In modern plants of Abies, it is found only in the species from Central America. (3) Undeveloped single flange. This type is represented by a small group of Abies from the west and east coastal area of the Pacific Ocean. (4) Undulate and developed single flange. This type is represented by most of the species of Abies, including all the species in Europe and most species in Asia and North America. The flange types mentioned above seem to have some relationships with the geographical distribution of the species in the genus Abies, and their occurrence might have not been completely influenced by the habitats, hence the features of the intercellular flanges may provide good evidence for the subgeneric division of Abies. Based on our results and those from the previously published literature about the infrageneric treatments of Abies and the distribution of the fossils, we consider that western North America might be the diversity center of modern Abies. Florin once pointed out that the characters of the leaf cuticle in gymnosperms are of great significance for the generic andinfrageneric division. This viewpoint is strongly supported by our study on modern Abies.     

Ecdysone titre and metabolism in relation to cuticulogenesis in embryos of Locusta migratoria

Eggs of Locusta migratoria contain remarkably high concentrations of ecdysone and several other ecdysteroids. During the time-span of embryonic development (11 days) 4 distinct peaks of ecdysone concentration (up to 8 μM) are observed in the egg, demonstrating the ecdysiosynthetic capacity of the embryo. Only during postblastokinetic development, is ecdysone efficiently hydroxylated to 20-hydroxyachieved through conjugation. On the basis of optical and electron microscopic observations, we have been able to correlate precisely each of the four peaks of ecdysone concentration in the egg with the time of deposition of a cuticle by the embryonic tissues (peak 1: serosal cuticle; peak 2: first embryonic cuticle; peak 3: second embryonic cuticle; peak 4: third embryonic cuticle).     

Histochemistry of the cuticle of the crab Menippe rumphii (Fabricius) (Crustacea: Brachyura) in relation to moulting

Histological and histochemical methods have been employed to study the formation and growth of the exoskeleton in relation to the moulting cycle of the crab Menippe rumphii (Fabricius). In the premoult condition the epidermal cells secrete a two-layered cuticle. Later these layers are widened by the secretions coming from the reserve cells, tegumental glands, and the Leydig cells. The fully formed cuticle of the intermoult crab is divisible into four layers, epicuticle, exocuticle, mesocuticle, and endocuticle.Histochemical observations on different cells have revealed that the tegumental glands secrete both neutral and acid mucopolysaccharides. The reserve cells are positive to PAS, BPB, Sudan Black B and Alizarin Red S techniques indicating the presence of carbohydrates, proteins, lipids, and mineral calcium. The Leydig cells are loaded with enzymes, including alkaline phosphatase, acid phosphatase, lipase, and phenoloxidase. Other histochemical tests have been employed to investigate the formation of different layers of the cuticle.     

Chitinous cuticle and systematic position of tardigrada

The chitinous nature of the cuticle, jaws and stomodaeum of three species of Tardigrada has been definitely proven using a specific micromethod involving a preparation of purified chitinase. These chemical characteristics are in favour of the phylogenetic closeness between Tardigrada and the Arthropoda.