Pattern in the Root Epidermis: An Interplay of Diffusible Signals and Cellular Geometry

The epidermis of roots is composed of hair and non-hair cells. Patterning of this epidermis results from spatially regulated differentiation of these cell types. Root epidermal development in vascular plants may be divided into three broad groups based on the mode of hair development; Type 1: any cell in the epidermis can form a root hair; Type 2: the smaller product of an asymmetric cell division forms a root hair; Type 3: the epidermis is organized into discrete files of hair and non-hair cells. TheArabidopsisroot epidermis is composed of discrete files of hair and non-hair cells (Type 3). Genetic and physiological evidence indicates that ethylene is a positive regulator of hair cell development. Genes with opposite roles in the development of hair cells in the shoot (trichomes) and hair cells in the root have been identified. Plants with presumptive loss of function alleles in theTRANSPARENT TESTA GLABRA (TTG)orGLABRA2(GL2) genes are devoid of trichomes indicating that these genes are positive regulators of trichome development. The development of supernumerary root hair cells in these mutant backgrounds illustrates that these genes are also negative regulators of root hair cell development. A model that explains the spatial pattern of epidermal cell differentiation implicates ethylene or its precursor 1-amino-1-cyclopropane carboxylate as a diffusible signal. Possible roles for theTTGandGL2genes in relation to the ethylene signal are discussed.     

Etude ultrastructurale de la glande urticante de la chenille processionnaire du pin,Thaumetopoea pityocampa schiff. (Lepidoptere : Thaumetopoeidae)

The urticating gland of Thaumetopoea pityocampa, (Lepidoptera : Thaumetopoeidae) caterpillar is formed of only trichogen cells. These cells form an irregular cluster, which seems to be multilayered, although there is only one layer of cells. Each trichogen cell produces urticating protein (thaumetopoein), forms urticating hair, and the thin cuticle in which the hair is implanted.     

Hair follicular cell/organ culture in tissue engineering and regenerative medicine

Hair follicles are complex organs composed of the dermal papilla (DP), dermal sheath (DS), outer root sheath (ORS), inner root sheath (IRS) and hair shaft. Development of hair follicles begins towards the end of the first trimester of pregnancy and is controlled by epidermal–mesenchymal interaction (EMI), which is a signaling cascade between epidermal and mesenchymal cell populations. Hair grows in cycles of various phases. Specifically, anagen is the growth phase, catagen is the involuting or regressing phase and telogen is the resting or quiescent phase. Alopecia is not life threatening, but alopecia often causes severe mental stress. In addition, the number of individuals afflicted by alopecia patients has been increasing steadily. Currently there are two methods employed to treat alopecia, drug or natural substance therapy and human hair transplantation. Although drug or natural substance therapy may retard the progress of alopecia or prevent future hair loss, it may also accelerate hair loss when the medication is stopped after prolonged use. Conversely, the transplantation of human hair involves taking plugs of natural hair from areas in which occipital hair is growing and transplanting them to bald areas. However, the number of hairs that can be transplanted is limited in that only three such operations can generally be performed. To overcome such problems, many researchers have attempted to revive hair follicles by culturing hair follicle cells or mesenchymal cells in vitro and then implanting them in the treatment area.     

An endoparasitic species of Pteromalidae (Hymenoptera: Chalcidoidea) attacking Aphidoletes aphidimyza (Diptera: Cecidomyiidae)

A solitary endoparasitic species of Pteromalidae (Hymenoptera: Chalcidoidea) was reared from pupae of an aphidophagous gall midge, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), in Japan. The parasitoid was identified as Gastrancistrus fuscicornis Walker, a species that has been recorded from Europe. An unidentified aphid has been proposed as being a host of G. fuscicornis, but the study reported here confirmed that G. fuscicornis is an endoparasitoid of A. aphidimyza. I consider that G. fuscicornis may not be a parasitoid of aphid. I found a nontentorial pit on the head of male and female of G. fuscicornis. According to the definition of the nontentorial pits, the pit found in G. fuscicornis corresponds to the facial pit. This is the first finding of the facial pit in Chalcidoidea. Morphological differences between G. fuscicornis and its allied species are provided.     

Proprioceptor organs in Cicadella viridis (L.) (Homoptera : Cicadellidae)

The external proprioceptor organs of Cicadella viridis (L.) (Homoptera: Cicadellidae) are identified and localized. They are composed of hair and campaniform sensilla grouped together and located in or near the joint areas of various parts of the body or in cuticular areas, which come into contact with moving parts. The hair sensilla, 8–75 μm long, are arranged in hair plates or in hair rows; they detect relative movement between parts of the body. Proprioceptor organs of this kind, localized in proximity to joint areas, were found on the legs and on the abdomen. Proprioceptor organs composed of hair sensilla located far from the articular areas were found on the 3rd pair of legs, the thorax, the hind wings, and the abdomen. The campaniform sensilla, which are arranged in fields and groups, in cuticular areas subject to deformations, are of 2 types: with raised caps (type I) and with flat caps (type II). Organs with campaniform sensilla were found on the legs, thorax and wings.     

NUCLEAR CHANGES DURING SPERMIOGENESIS IN A PULMONATE SNAIL

Changes in both external form and internal arrangement of nuclear material have been investigated in the differentiation of the sperm of the pulmonate snail, Otala lactea. Sperm head differentiation begins with a flattening of the previously spherical nucleus and a thickening of the nuclear envelope covering the anterior and posterior surfaces of that nucleus. Tail filaments can be seen in the cytoplasm at this time. At a slightly later period the mitochondria begin to form the tail filament sheath and at this time the nucleus begins to elongate in a direction parallel to the future axis of the sperm. At the same time the nuclear material begins to orient itself at right angles to the nuclear surface which lines the pit occupied by the centriole. As nuclear elongation proceeds, this orientation of nuclear substance takes on the appearance of 60 A thick sheets bent in a direction parallel to the sperm axis. Soon the sheets fill the entire nucleus. The nucleus then begins to twist along its axis so that it starts to take on the mature, flame-shaped form. At this time the flat sheets begin to disappear and in the mature sperm head they are no longer visible (see Text-fig. 2 B).     

Nitric Oxide Functions as a Positive Regulator of Root Hair Development

The root epidermis is composed of two cell types: trichoblasts (or hair cells) and atrichoblasts (or non-hair cells). In lettuce (Lactuca sativa cv. Grand Rapids var. Rapidmor oscura) plants grown hydroponically in water, the root epidermis did not form root hairs. The addition of 10 µM sodium nitroprusside (SNP), a nitric oxide (NO) donor, resulted in almost all rhizodermal cells differentiated into root hairs. Treatment with the synthetic auxin 1-naphthyl acetic acid (NAA) displayed a significant increase of root hair formation (RHF) that was prevented by the specific NO scavenger carboxy-PTIO (cPTIO). In Arabidopsis, two mutants have been shown to be defective in NO production and to display altered phenotypes in which NO is implicated. Arabidopsis nos1 has a mutation in an NO synthase structural gene (NOS1), and the nia1 nia2 double mutant is null for nitrate reductase (NR) activity. We observed that both mutants were affected in their capacity of developing root hairs. Root hair elongation was significantly reduced in nos1 and nia1 nia2 mutants as well as in cPTIO-treated wild type plants. A correlation was found between endogenous NO level in roots detected by the fluorescent probe DAF-FM DA and RHF. In Arabidopsis, as well as in lettuce, cPTIO blocked the NAA-induced root hair elongation. Taken together, these results indicate that: (1) NO is a critical molecule in the process leading to RHF and (2) NO is involved in the auxin-signaling cascade leading to RHF.Key Words: auxin, nitric oxide, root hair, lettuce, arabidopsis, nos1 mutant, nia1, nia2 mutant     

Ultrastructure des sensilles trochanteriens de Campodea sensillifera conde et mathieu (Diplura : Campodeidea)

The fine structure of the basiconica sensilla situated on the posterior part of trochanters in Campodea sensillifera (Diplura : Campodeidea) reveals that they are probably olfactory and mechano-sensitive setae. Each sensillum is composed of one sensory axis made of 3 dendrites ensheathed by 3 cells (thecogen, trichogen and tormogen); one outer segment ends by a tubular corper without connection with the cuticular layer. The setae are generally racket-shaped. The epicuticular layer of the expanded part is perforated by a lattice of numerous slits, which communicate with underlying canals. The ciliary structures and apex of the tormogen cell are eliminated just before ecdysis. The ciliary microtubules are present in the cavity of the new sensillum, but after ecdysis the microtubules persist only at the lower part of the peduncle. An ecdysial canal appears at the tip of the sensillum.     

A lectin histochemical study on carbohydrate moieties of the gonadotropin-like substance in the epithelial cells of Hatschek's pit ofBranchiostoma belcheri

The present light microscopic lectin, histochemical study suggests for the first time that the vertebrate gonadotropin-like substance in the basal part of the epithelial cells of Hatschek's pit is a sialic acid-containing glycoprotein. The binding intensity of the epithelial cells in Hatschek's pit to 6 lectins (Limulus polyphemus agglutinin (LPA), Wheat germ agglutinin (WGA),Helix pomatia agglutinin (HPA), Concanavalin A (Con A),Ulex europaeus agglutinin I (UEA I) andRicinus communis agglutinin I (RCA I)) indicate that the carbohydrate composition of the gonadotrophic glycoprotein is similar to that of mammals and fish, and that N-acetyl-D-galactosamine, sialic acid, glucosamine, D-mannose and L-fucose are components of the carbohydrate portion.     

Structure de la paroi de Aremoricanium rigaudae Deunff, 1955 (Acritarche,Ordovicien)

The wall of Aremoricanium rigaudaeDeunff, 1955, type-species by original designation of the genus AremoricaniumDeunff, 1955, is composed of two layers: the internal one has a circular opening while the second is the only one which develops the processes and a tubular expansion.     

Xylem of early angiosperms: Novel microstructure in stem tracheids of Barclaya (Nymphaeaceae)

Pit membranes of stem tracheids of all recognized species of Barclaya, an Indomalaysian genus of Nymphaeaceae, were studied with scanning electron microscopy (SEM). Pit membranes of the tracheids are composed of two thick layers, both constructed of fibrils much larger than those of tracheary elements of angiosperms other than Nymphaeaceae. The outer (distal) layer, which comprises the continuous primary wall around the tracheids, is spongiform, perforated by porosities of relatively uniform size, and confined to or most prominent on end walls of stem tracheids. The second layer consists of thick widely spaced fibrils that are oriented axially and are laid down proximally (facing the cell lumen) to the first (outer) layer, although continuous with it. These axial fibrils are attached at their ends to the pit cavities. This peculiar microstructure is not known outside Nymphaeaceae except in Brasenia and Cabomba (Cabombaceae, Nymphaeales), and has not been previously described for Barclaya. The longitudinally oriented threads and strands in perforation plates of secondary xylem of wood and stems of a variety of primitive woody angiosperms (e.g., Illicium) are not homologous to the pit membrane structure observed in stem tracheids of Barclaya, which, like other Nymphaeaceae, has only primary xylem and no perforation plates. The tracheid microstructure reported here is different from pit structures observed in any other group of vascular plants, living or fossil. The tracheid stem microstructures of Barclaya and other Nymphaeaceae appear to be a synapomorphy of Nymphaeaceae and Cabombaceae, and need further study with respect to ultrastructure and function.     

FINE STRUCTURE OF CHROMOSOMES

Electron micrographs of staminate hair cells of Tradescantia reflexa indicate that early prophase chromosomes are composed of a number of helically arranged chromonemata. Favorable preparations reveal as many as 64 identifiable subsidiary strands, assumedly arranged as intertwined pairs to form a hierarchy of pairs of pairs. The helices of the smallest discernible units have a diameter of about 125 A, with highly electron-scattering material disposed peripherally around a less dense "core." The wall of this peripheral ring has a thickness of about 40 A, and apparently represents another pair of coiled threads surrounding a 40 A central axis. The implications of the findings are discussed briefly.     

Cortical microtubules and microfibril deposition in the cell wall of root hairs ofEquisetum hyemale

Summary The cell wall of root hairs ofEquisetum hyemale is shown to be composed of three different cell wall textures. The growing cell wall at the tip of the hair is composed of a dispersed texture of microfibrils, which continues along the outside of the whole hair. With increasing distance from the tip an increasing number of helicoidally arranged lamellae is deposited. These findings correspond with the observed isotropism of young hairs in polarized light.Hairs of approximately 4 days old become positive birefringent, indicating that longitudinally oriented layers prevail over layers with a transverse direction. This phenomenon starts at the base of the hair. Full-grown hairs are positive birefringent up to the tip and concordantly show a thick additional inner cell wall layer which forms a helical pattern the length of the hair, with a mean microfibril angle of 25 with the cell axis.Cortical microtubules, subjacent to the dispersed, the helicoidal and the helical wall texture are axially aligned and, thus, not in coalignment with the last deposited microfibrils.Coated and smooth vesicles are present in the cortical cytoplasm of both growing and full-grown hairs. Electron-dense profiles (20 nm in diameter), surrounded by a halo (of 50 nm) were observed on the wall-plasmalemma interface in full-grown hairs only. A relation of these structures with microfibril deposition could not be demonstrated. They might represent channels transporting material to the wall, which, in full-grown hairs, is heavily impregnated with a tawny brown substance.The general hypothesis that cortical microtubule orientation directs microfibril deposition is disputed.     

Le genre Murciella (Foraminifère, Rhapydionininae), dans le Crétacé supérieur de Grèce (zone de Gavrovo-Tripolitza)

Several new species are described, of which theendoskeletal features present strong similarities with YaberinellaVaughan. Each chamber consists of: 1) a single peripheral layer of tubular «primary chamberlets perpendicular to the septa they join, 2) concentric inner layers of tubular «secondary chamberlets oriented obliquely to the preceding, each layer inclined in the contrary sense to its inner and outer neighbour, and the inclination being symmetrical with respect to any radial plane. Thus the secondary chamberlets form two helices, each with the same axis, which is also the axis of the chamber and the axis of growth: this is called «helicoidal structure. Lateral connections exists between the tubes of different layers («stolons).The chamber arrangement, and above all the presence of a preseptal space equipped with buttresses exclude the new species from Yaberinella and permits their assignment to the sub-family Rhapydionininae, more precisely to the genus MurciellaFourcade, of which several known sections (particularly the holotype of the type-species) seem to show the same organisation.The mode of coiling shown by some of the new forms, together with the lateral connection between chamberlets (the function of which might be the same as that of the preseptal space) permit the advocation of a development from Murciella (Tethysian, Upper Cretaceous) to Yaberinella (central American, Eocene).     

Sensory pits – Enigmatic sense organs of the nymphs of the planthopper Issus coleoptratus (Auchenorrhyncha,Fulgoromorpha)

The sensory pits of the nymphs of the planthopper Issus coleoptratus were investigated using light and electron microscopic techniques. Sensory pits consist of a bowl-shaped depression in the cuticle (25–70 μm in diameter) covered by a transparent cupola of presumably waxy material. Each pit is equipped with a long sensory hair that emerges from the inner wall of the pit and extends horizontally for about two thirds of the pit diameter. The cupola emerges from the rim of the pit opposite to the socket of this hair. Additional small sensory hairs extend into the base of the cupola. While the ultrastructure of these small hairs resembles that of other mechanoreceptive sensory hairs of insects, that of the long hairs shows several peculiarities. Sensory pits are dispersed over the frontal part of the head, the tergites of thoracic and abdominal segments. On the different parts of the exoskeleton, the orientation of long hairs within the pits varies in a systematic fashion with respect to the body axes. Size, location, and orientation of the pits show almost perfect bilateral symmetry. Their number increases with each moult. Comparative data show that the level of structural complexity of these sense organs varies considerably within this group of insects.     

Hirsutism: Diagnosis and management

Background:Hirsutism is defined as excess hair growth in androgen-dependent areas of the body in women.Objective: This article provides an updated review of hirsutism, focusing on the etiologies, clinical features, approach to diagnostic evaluation, and treatment options.Methods: The PubMed database was searched for English-language articles published from 1981 to the present, using the terms hirsutism, polycystic ovarian syndrome, congenital adrenal hyperplasia, hirsutism diagnosis, and hirsutism treatment. Reference lists from review articles on hirsutism during this time period were also examined.Results: While there are many causes of hirsutism, the majority of patients have a benign process that may be idiopathic. In some circumstances, hirsutism is a sign of functional ovarian hyperandrogenism or congenital adrenal hyperplasia. Even more rarely, it is the presenting sign of an internal malignancy.Conclusions: Hirsutism clinically presents in women as excessive hair growth in androgen-dependent areas. It is a particularly important diagnosis to make, because it often significantly affects a woman's perception of her femininity and less commonly can be a sign of an underlying malignancy or a cutaneous manifestation of a condition with significant cardiovascular or other morbidity. A variety of treatments exist to help minimize the appearance of unwanted hair.     

THE ELECTRON MICROSCOPY OF THE HUMAN HAIR FOLLICLE : PART 1. INTRODUCTION AND THE HAIR CORTEX

1. The presumptive cortical cells of hair in the undifferentiated matrix of the bulb contain mitochondria, agranular vesicles, and many small dense R.N.P. particles, but no keratin, pigment granules, or endoplasmic reticulum. 2. In the mid-bulb region intercellular adhesion is limited to small localised areas. Intercellular gaps are common and the cell surfaces are irregularly convoluted. The melanocyte processes penetrate the cell gaps. The relation between their pigment-bearing tips and the involutions of the cell membranes suggests an active phagocytosis of the tips. 3. Fibrous keratin first appears in loose parallel strands of fine filaments (ca. 60 A diameter) in the mid-bulb. The filaments, the long mitochondria, and elongated nucleus are all parallel to the long axis of the cell and the axis of the follicle. 4. At the level of the constriction of the bulb and above, a dense amorphous substance appears between the fine filaments and apparently acts as adhesive cement. The bundles of filaments now form well defined fibrils. The packing of the filaments within the fibrils is in places hexagonal and elsewhere in the form of "whorls." 5. At higher levels further filaments and interfilamentous cement are added together and the whole cytoplasmic space becomes packed with fibrils which finally condense to massive blocks of keratin. The residual cellular material occupies the interstices. 6. The addition of the interfilamentous substance is regarded as an essential factor in keratinisation. Keratin is considered to be a complex made of fine filaments (α-filaments) embedded in an amorphous substance (γ-keratin) which has the higher cystine content. 7. The wide-angle fibre-type x-ray pattern is thought to be due to scattering by the fine α-filaments and some low angle lateral spacings to the filament-plus-cement structure.     

The comparison of hair from gastric cancer patients and from healthy persons studied by infrared microspectroscopy and imaging using synchrotron radiation

Objective: The objective is to apply synchrotron-based FTIR microspectroscopy and imaging to human hair tissue and investigate the possibility of the method in gastric cancer research and diagnosis. Methods: Human hair from gastric cancer patients’ scalp and normal persons’ scalp were studied by synchrotron-based FTIR microspectroscopy and imaging. Results: The micro-spectra and imaging show the difference between the normal and malignant hair tissues. Obvious peak shift of symmetric phosphate band is observed in micro-spectra of medulla region for the hair tissue of gastric cancer patients. Chemical imaging shows the distributions of lipid and amide II/v_sPO₂^? have changed in the gastric cancer cases. Conclusions: The study indicates that the hair tissue's infrared microspectroscopy and imaging using synchrotron will be a potentially useful method for rapid early gastric cancer diagnosis.     

Comparative study of the antennal sensilla of five species of root maggots: Delia radicum L., D. floralis F., D. antiqua Mg., D. platura MG. (Diptera : Anthomyiidae) and Psila rosae F. (Diptera : Psilidae)

A comparative study of the antennal sensilla of Delia radicum L., D. floralis F., D. antiqua Mg., D. platura Mg. (Diptera : Anthomyiidae) and Psila rosae F. Diptera Psilidae) is undertaken. For both sexes of each species, the type, distribution, and density of sensilla are determined. All 5 species have trichoid (olfactory) and grooved (olfactory) sensilla. Basiconica I (blunt) sensilla (olfactory) are found on each of the species examined, except D. platura. Basiconica II (tapered) (olfactory) and clavate (olfactory) sensilla are found only on Delia species. Also, only Delia species have single-chambered, dorsal pits, and these contain basiconic II pit sensilla (olfactory). Common to all 5 species is a multi-chambered ventral pit (olfactory). In the ventral pit, all 5 species have grooved pit sensilla (olfactory). In addition to this type of sensillum the Delia species have smooth-walled conical pit sensilla (hygro-/thermosensitive) and P. rosae has granular pit sensilla (hygro-/thermosensitive). Smooth-walled tapered pit sensilla (hygro-/thermosensitive) are found in D. radicum. Similarities and differences in the density of surface sensilla between dorsal and ventral funicular surfaces, male and female flies, and oligophagous (D. antiqua, D. radicum, D. floralis and P. rosae) and polyphagous (D. platura) species are compared. Several differences in sensillum density between the dorsal and ventral funicular surfaces are observed, but these do not fit into a consistent trend. Except for D. radicum, there are differences in sensillum density between male and female flies. For the oligophagous species, females have a greater sensillum density, whilst for the polyphagous D. platura males have a greater sensillum density. Comparisons between species show the greatest differences between the Delia species and P. rosae, and within the 4 Delia species, differences in sensillum density do not correlate with host range or body size.     

Une piste avec traces de soies épaisses dans le Trias inférieur a moyen de Lodève (Hérault,France): Cynodontipus polythrix nov. gen., nov. sp. les Cynodontes en France

A new ichnological genus, Cynodontipus species-type C. polythrix) has been created to define the unusual tract of a large but still unknown hairy Vertebrate of the Early to Middle Trias, Southern France. Horizon: just below the Chirotherium white sandstones slabs at Fozières (Hérault).This new type of footprint indicates that, as early as the Middle Trias, some Vertebrates were covered with an abundant protection of hair. A short systematic comparison is attempted with the last big Therapsids of that age, mainly the Cynodonts.