High Hair Density Research Articles

All that shimmers is not the same: silvered leaves and micromorphological diversity in Timonius DC. (Rubiaceae)

The significance of leaf micromorphology in distinguishing species and higher taxa has been well established in several plant groups, but has not been well studied in Timonius. This deserves some attention because (1) leaves are most commonly represented in herbarium specimens; (2) leaf micromorphology may facilitate the recognition of male and female specimens of the same species in dioecious taxa with sexually dimorphic inflorescences and flowers, such as Timonius, and (3) silvery lower leaf lamina surfaces occur in several Timonius species. The micromorphology of the lower lamina surface of 12 Timonius species was examined using scanning electron microscopy to establish the taxonomic utility of lower lamina micromorphology and to investigate if species with silvery leaf undersides share similar leaf micromorphological traits. For all Timonius species examined, the leaf hairs are unbranched and non-glandular. Hair morphology and density were found to be uniform within species but vary substantially between species. The silvery leaved species are typically characterised by one or more of the following leaf traits—long hair length, high hair density, and the presence of lanate hairs. Nevertheless, different combinations of these three traits result in much leaf micromorphological diversity, enabling distinction among the silvery leaved species based on leaf hair characters.

Memory regulatory T cells reside in human skin

Regulatory T cells (Tregs), which are characterized by expression of the transcription factor Foxp3, are a dynamic and heterogeneous population of cells that control immune responses and prevent autoimmunity. We recently identified a subset of Tregs in murine skin with properties typical of memory cells and defined this population as memory Tregs (mTregs). Due to the importance of these cells in regulating tissue inflammation in mice, we analyzed this cell population in humans and found that almost all Tregs in normal skin had an activated memory phenotype. Compared with mTregs in peripheral blood, cutaneous mTregs had unique cell surface marker expression and cytokine production. In normal human skin, mTregs preferentially localized to hair follicles and were more abundant in skin with high hair density. Sequence comparison of TCRs from conventional memory T helper cells and mTregs isolated from skin revealed little homology between the two cell populations, suggesting that they recognize different antigens. Under steady-state conditions, mTregs were nonmigratory and relatively unresponsive; however, in inflamed skin from psoriasis patients, mTregs expanded, were highly proliferative, and produced low levels of IL-17. Taken together, these results identify a subset of Tregs that stably resides in human skin and suggest that these cells are qualitatively defective in inflammatory skin disease.

Leaf Morphological and Stomatal Variations in Paper Birch Populations along Environmental Gradients in Canada

Variations in leaf morphology and stomatal characteristics have been extensively studied at both inter- and intraspecific levels although not explicitly in the context of paper birch (Betula papyrifera Marsh) populations. The birch populations might have developed the leaf variations that allowed them to adapt to a wide climatic gradient. Therefore, in this study we examined variations in the leaf morphological and stomatal characteristics of sixteen paper birch populations collected across Canada and grown in a common garden. We also examined the relationship between these leaf characteristics and the climate of the population’s origin. Significant genotypic differences were found in the leaf characteristics measured among the birch populations. Thus, we expected that the observed leaf variations may be partly explained as natural diversity in the birch due to differences in environment of origin. We noticed that along mean annual precipitation and aridity gradients, hair density on leaf adaxial surface had decreased whereas stomatal density increased significantly. Our results showed that the populations with larger leaf area and specific leaf area had higher hair density but low stomatal density. These leaf characteristics provided a structural basis in reducing water loss through leaves and increasing water use efficiency. A trade-off between stomatal area and density resulted in this study might be a strategy of the birch to balance stomatal conductance in decreased precipitation.

Sensilla Density Corresponds to the Regions of the Horn Most Frequently Used During Combat in the Giant Rhinoceros Beetle Trypoxylus dichotomus (Coleoptera: Scarabaeidae: Dynastinae)

Abstract In the Japanese horned beetle, Trypoxylus dichotomus (L.), males have a long forked head horn that they use in fights with other males over access to sap sites that attract females. Because of the high risk of injury from these contests, males should assess the fighting potential of their rivals before escalating to direct combat. Indeed, male rhinoceros beetles only escalate to intense fighting when matched with equal-sized rivals. Males often tap their opponents with their head horn before and during fights, so it is likely that beetles assess the size of their competitors via sensory input from their horns. Here, we used scanning electron microscopy to examine the density and distribution of sensory hairs along the length of the males’ horn. To assess the potential functional significance of variation in hair density, we combined our microscopy observations with a behavioral analysis of how males use their horns during fights. We found a strong correlation between the density of sensory hairs and the regions of the horns that were used most during combat. The distal tips of the horns had the highest hair density, and were also the region of the horn most frequently in contact with an opponent. Given the shaft and socket morphology of these hairs, which is the characteristic morphology of mechanoreceptors, we expect that they provide mechanosensory input. Thus, although beetle horns are often described as dedicated weapons, our results suggest that the head horns of T. dichotomus also play an important sensory role.

Influence of leaf pubescence on the behavior of the two-spotted spider mite (Tetranychus urticae) and the European red mite (Panonychus ulmi)

Movement behavior of two mite species: two-spotted spider mite (Tetranychus urticae) and European red mite (Panonychus ulmi) on leaves of some apple cultivars (´Greensleeves´, ´Spartan' and SA 455-2 selection) with different density of pubescence was analysed. Assessment of the leaf pubescence density was performed using an originally developed quick method based on digital pubescence mage analysis. For P.ulmi, both stop time and average speed did not depend on kind of leaf. In contrary. T.urticae revealed higher movement activity on slight pubescent leaves compared to leaves with high leaf hair density.

Control Light Delivery in PDT by Taking Account the Optical Properties of Hair Density on the Skin Surface

Information concerning energy deposition during laser therapy of skin is needed to comprehend and asses the results of clinical procedures in dermatology. The prupose of this study is to show an optical model that predicts infection dose for the skins in different hair density and which can be used to explore whether parameteres of hair on the skin surface, merited the bio optical sudies and phsician during irradiation. A skin optic study by the advanced system analysis program (ASAP) software represents the best way for improving investigation of light propagation into the skin. The ASAP technique of the skin modeling is the process of constructing optical objects, such as a set of skin layers and propagation of a laser beam, whose behavior or properties correspond in some way to a particular real-wold system. The results showed that, hair on the skin surface minimized dose injection of the skin target during the PDT procedure. The differences in penetrating injection dose for layers of skin between low and high hair densities after irradiation, for end epidermis layer at 0.098 mm in the skin region with high and low hair density are 832.1 mW.mm-3 and 853 mW.mm-3 respectively, but for skin without hair is mW.mm-3. Using this resutl, we found that the region of decreased light fluence rate that formed at the epidermis layer significantly reduces the power uptake in deep layers. Moreover, hair density on the skin surface precents light penetration into the deeper region. Therefore, if the hair parameters are ignored, a relatively significant effect of the dose rise occurs in a deeper area resulting great influence in depth of target.

Root architecture of six tropical seagrass species, growing in three contrasting habitats in Indonesian waters

Although several recent studies point at the importance of seagrass roots for nutrient acquisition in oligotrophic tropical ecosystems, remarkably little is known about the root architecture of tropical seagrasses. The present study provides a detailed description of the root architecture of six seagrass species that were extracted from three sites differing in sediment type and nutrient availability (i.e., except for one species that was not present at one of the sites). Number of roots per node, order of root branching, length and diameter per root order, root hair density and length were determined and used to calculate a topological index for the different species and habitats. Root architecture differed strongly between species. The relatively long-lived and slowly-growing species Thalassia hemprichii and Enhalus acoroides were characterised by short internodes with relatively few unbranched roots per node and a high root hair density. More fast growing species such as Cymodocea rotundata, Cymodocea serrulata and Syringodium isoetifolium had many roots per node, the majority of which were branched. Surprisingly, differences in sediment type and nutrient availability, as present between locations, had little effect on root architecture. We expect this to be due to a relatively homogeneous nutrient distribution at the small scale within water saturated sediments. Overall, all seagrass species had relatively simple branching (topological index > 0.7), comparable to angiosperms of the low temperate salt marsh. We speculate that relatively simple root architecture of plants in flooded systems reflects the need for a minimal path length for oxygen transport from shoots to roots.

Intraspecific variation in Capsella bursa‐pastoris in plant quality traits for insect herbivores

SummaryThe arable plant Capsella bursa‐pastoris is phenotypically variable in many life history traits, particularly time from germination to flowering. The hypothesis was investigated that, associated with this variation, there are differences in traits that influence plant quality for insect herbivores. Significant within‐species variation was found in plant growth, leaf surface characteristics and tissue nutrient composition among 21 accessions of Capsella. Short flowering time plants exhibited slow vegetative growth, relatively large shoot nitrogen content, high leaf hair densities and differences in phloem composition, compared with long flowering time plants. Insect herbivore response to distinctive trait combinations was assessed on a subset of seven accessions using the phloem‐feeding aphids Aphis fabae and Myzus persicae. Variation in aphid performance was small but significant, with 15–25% fewer nymphs produced on plant variants that exhibited greater tissue water content and low tissue C:N ratio (A. fabae) or on variants with less phloem nitrogen (M. persicae). The differential responses exhibited by the two aphid species to the test accessions confirmed that quantifying intraspecific plant variation is a necessary first step in understanding plant functional diversity and its impact on consumers in arable systems.

Environmental effects on morphology of Acacia tortilis group in the Red Sea Hills, North-Eastern Sudan and South-Eastern Egypt

Acacia tortilis is a drought-resistant species. Its survival and existence in the arid and semi-arid area of Northern Africa and Arabian Peninsula is due to its ability to endure the harsh condition and therefore, it is generally forms open pure stands or mixed stands in these drylands. Wherever it grows, it plays an important role in human, animal and other plant species lives. Yet the relation between its adaptive features and their relation to the environmental conditions is not studied in a large scale of environmental variation. The main objective of this study is therefore to examine if the immediate environmental factors, other than human utilization, are associated to the expressed morphological variables among the A. tortilis sub-taxa. Three subspecies are collectively reported in the study area, Red Sea Hills of Sudan and Egypt. According to different literatures, they are distinguished by features of high plasticity under the variable pressure of human activity and climate. Such features are hair density in some parts of the plant, crown shape and number of stems. In the current study, the result of analysing 520 samples of A. tortilis – collected from 25 different localities representing various altitudinal gradients – showed a correlation between the expressed morphological studied and the immediate environment. When data from both regions studied as one data set, elevation, above sea level, was the only significant response variable and higher hair density was associated to plants growing in Sudan. However, when only data from Sudan was studied separately, elevation, hillside and lower part of the catchment were the statistically significant response variables. In the Egyptian data set, the statistically significant response variables were elevation, khor bank and the upper, mid, and lower part of the catchment. An intra-morphological correlation was also shown. These results may suggest that the current A. tortilis sub-taxa are ecotype. Genetic and anthropogenic studies are needed to verify this assumption.

Female patients complaining about hair loss: documentation of defective scalp hair dynamics with contrast‐enhanced phototrichogram

The complaint of chronic hair loss frequently affects female subjects and there is little or no objective technology available in the general dermatology or even in the hair clinics to guide the observer in the management of the patient. The purpose of this report is to share the results of refined hair growth measurements that were collected in 92 female subjects complaining about hair loss. Clinically they were classified as having a patterned hair loss according to Ludwig (L; n=50), diffuse hair loss (D; n=13) or no visible hair loss but complaining of hair shedding (N; n=29). Two scalp sites on the top of the head and one occipital site were investigated after clipping by close-up photography before and after a hair dye (contrast enhancement, CE). Forty-eight hours later a new photograph was taken after CE in view of phototrichogram analysis (CE-PTG). Finally a last hair clip was performed 30 days later and hair thickness and length determined for linear growth measurements (LHGR). Herein we confirm that the top of the head shows usually a higher hair density than occipital sites, a physiological observation that applies both to men and women. From the technological perspective, we also document that CE improves hair detection in all sites. Interestingly, in affected patients (L and D) the relative increase of hair counts after CE was much higher (range +22.4% to +28.3%) compared with apparently unaffected females (N; range +8.2% to +9.7%). This increase in hair counts was only due in part to the presence of less pigmented thinning hair (thickness less than 40 microm). Such thin hairs were found in statistically significantly higher proportions in younger patients with mildly severe (grade I) patterned alopecia (Ludwig: L). In other patients with hair loss and in more severe forms of patterned alopecia - especially in older patients - the thin hair is not detected in abnormal proportions. In all sites slower growth rates and decreased anagen percentages indicate a defective hair replacement programme distinguishing L patterns from diffuse hair loss and from apparently unaffected patients complaining of chronic hair loss. Globally, we also noted that increasing age is associated with significant regression of scalp hair (decreased hair counts, thinner hair and slower LHGR). On the basis of the present data together with female data from the literature and our own studies in male subjects, we suggest a three-step mechanism leading to hair loss 1. Shortening of growth phase the hair cycle with maintained thick hair, i.e. more frequent hair cycling that leads to more hair shedding. 2. Intermittent production of short thin hair, i.e. morphological evidence of miniaturisation. 3. Very occasional or almost no hair production, i.e. dormant follicles or irreversible follicular atrophy. Depending on the genetic background, hormonal microenvironment in the scalp and conditioning of individual hair follicle bio-responses, female and male patterned hair loss may end up into different phenotypes.

Nondestructive assessment of leaf chemistry and physiology through spectral reflectance measurements may be misleading when changes in trichome density co‐occur

Reflectance indices are frequently used for the nondestructive assessment of leaf chemistry, especially pigment content, in environmental or developmental studies. Since reflectance spectra are influenced by trichome density, and trichome density displays a considerable phenotypic plasticity, we asked whether this structural parameter could be a source of variation in the values of the most commonly used indices. Trichome density was manipulated in detached leaves of three species having either peltate (Olea europaea and Elaeagnus angustifolius) or tubular (Populus alba) trichomes by successive removal of hairs. After each dehairing step, trichome density was determined by light or scanning electron microscopy and reflectance spectra were obtained with a diode-array spectrometer. Although species-specific differences were evident, most of the indices were considerably affected even at low trichome densities. In general, the less-affected indices were those using wavebands within the visible spectral region. The index that could be safely used even at very high hair densities in all species was the red edge index (lambda(RE)) for chlorophyll. The results indicate that changes in reflectance indices should be interpreted cautiously when concurrent changes in trichome density are suspected. In this case, the red edge for chlorophyll content may be the index of choice.

Histological features of peripilar signs associated with androgenetic alopecia.

A study of the scalp in a large cohort of volunteers with androgenetic alopecia using macrophotographs showed the presence of peripilar signs (PPS) around the hair ostia. The aim of the present study was to establish the histopathological features related to PPS. Prospective clinicopathological study. SETTING. Department of Dermatology, University Hospital of Bologna. A group of 40 patients (21 males and 19 females) participated in the study. Macrophotographs of the scalp were taken using a Dermaphot camera and PPS were scored using a three-point scale. Hair density and PPS were clinically scored according to reference scales. Two punch biopsies from the photographed area were obtained from each subject and histological analysis was performed on vertical and horizontal sections. Clinical parameters indicated that PPS were already detectable on scalp with high hair density. Moreover, in patients with high hair density (score >4), a significant relationship was found between the PPS score and the global score for perifollicular infiltrates. Thus PPS are linked to superficial perifollicular lymphocytic infiltrates in early androgenetic alopecia. PPS could be the clinical signs reflecting the presence of perifollicular infiltrates.

Pre‐ and post‐landing response of the parasitoid Encarsia formosa to whitefly hosts on Gerbera jamesonii

AbstractOne of the factors that may complicate biological control of the greenhouse whitefly on Gerbera jamesonii by Encarsia formosa is the rosette shape of this ornamental, which differs from the vertical shape of most vegetable plants (cucumber, egg plant, tomato, etc.). Therefore, host‐habitat location and the behaviour prior to landing on uninfested and infested leaves was studied. Attraction of E. formosa from a short distance by infested leaves could not be detected: the parasitoid females landed at random on uninfested and infested leaves. After the first landing, a redistribution of the wasps occurred on the leaves. After 24 h three times as many wasps were found on the infested leaves than on uninfested ones. In a dispersal experiment with four plants, E. formosa appeared to have no preference for landing on leaves of the medium age class, which is the age class on which most of the whiteflies in a suitable stage for parasitism occur. Twenty percent of the parasitoids were found on the plants 20 min after releasing them. These results were independent of the plant cultivar and the host density on the plants. In the course of 8 h, the number of E. formosa females recovered from plants increased linearly, and this increase was greater on plants where hosts were present and also greater on the plant cultivar with the lowest trichome density. After 24 h, the percentage of females was highest (56%) on plants with the highest host density. E. formosa females were arrested on leaves where hosts were present. Contrary to our expectation, the results from the two G. jamesonii cultivars that differed strongly in leaf hairiness were not significantly different in most experiments. Only at the high host density was parasitism found to be lower on the cultivar with the higher hair density. Parasitoids may walk on top of the ‘hair coverlet’ of cultivars with high trichome density and, therefore, be hampered less than expected.

Some aspects of pod characteristics predisposing pigeonpea ( Cajanus cajan (L.) Millsp.) to infestation by Callosobruchus chinensis (L.)

Investigations with pigeonpea ( Cajanus cajan) genotypes ‘Apio-elina’ and ‘PI-397566’ showed that certain pod characteristics influenced both infestation in the field by Callosobruchus chinensis and damage caused by this pest. Compared to pods with no or sparse hair, pods with thick hairs suffered greatly reduced field infestation due to the barrier effect of the hairs on oviposition and larval penetration. Even on pods with no or few hairs, the pod wall appeared to offer some resistance to both larval penetration and adult emergence. High levels of infestation by C. chinensis were recorded on pigeonpea pods with no or few hairs, those with pods damaged through shattering, and those with pods that had been previously damaged by pod borers. From the results of the study, it was recommended that pigeonpea selection should include screening for high pod hair density and thicker pod wall.

Structure of the Sensory Innervation of the Anal Canal in the Pig

The sensory innervation of the anal canal of the pig was investigated by light and electron microscopy. The distribution of the different types of sensory nerve endings correlates with the histology of different zones: (1) After the rectal mucosa there was a zone lined with nonkeratinized stratified squamous epithelium. (2) A middle zone was lined with keratinized stratified squamous epithelium. Here the dermis already showed a papillary and reticular layer. (3) The last zone showed hairy skin with a high hair density. The following nerve endings were found: Free nerve endings reached the stratum superficiale in nonkeratinized squamous epithelium and the stratum granulosum in the keratinized squamous epithelium. Dermal free nerve endings were found in all zones near the epithelium and two different types were identified as those derived from C-fibers and those from A-delta-fibers. Merkel nerve endings showed different features depending on their location. Few Merkel-like cells were found in the epithelium of the anal crypts. Typical Merkel Tastscheiben were located at the base of epithelial ridges or pegs in zones 2 and 3. The number of Merkel cells varied up to 200. The myelinated afferent fiber supplied 10-15 Merkel cells. Merkel cells were also found regularly in the outermost layer of the external rooth sheath of hair follicles at about the same level as perifollicular nerve endings. Lamellated corpuscles were found in the dermis of all zones except the cranial part of zone 1, where the anal crypts are located. Generally they consisted of a central nerve terminal which may be branched. Each terminal was surrounded by an inner core of concentrically arranged lamellae of the terminal Schwann cell and one or several inner cores were included in a capsule of perineural cells. The size of the corpuscle, the regularity of the inner core and the number of capsular layers depended on the location of the corpuscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomie und Entwicklung der Blasenhaare von Chenopodium-Arten

Species from the genus Chenopodium carry various types of hairs: Bladders are restricted to the subgenus Chenopodium , glandular hairs to the subgenus Ambrosia , additionally articulated hairs do occur in both taxa. Two types of bladders are distinguished: 1) Bladders with one glandlike stalk cell and a big bladder cell. They are structured identically with those in Atriplex species. 2) Bladders with a small bladder cell and several vacuolized stalk cells which at no stage of development show any glandular character. On young leaves the glandlike bladders form several layers, the other type of hairs occurs in lower density and is accompanied by articulated hairs. The basipetal development of bladders is restricted to the youngest leaves, so highest hair density is found near the shoot tip. Decreasing- hair density on older leaves does not only depend on the expansion of leaves, but also on the increasing number of bladders formed on younger leaves. Furthermore, two types of glandular hairs are described: 1) Hairs with a vacuolized stalk and a small, glandular outmost cell which contains secret granula, but no chloroplasts, and no central vacuole. 2) Hairs with a big outmost excretion cell and some glandular stalk cells containing a lot of plastides. Their structure shows a striking functional parallelity to glandlike bladders.

HOST PLANT RESISTANCE TO OPHIOMYIA PHASEOLI (TRYON) (DIPTERA: AGROMYZIDAE) IN PHASEOLUS VULGARIS

AbstractFifteen entries representing thirteen cultivars of Phaseolus vulgaris were evaluated for nonpreference and antibiosis resistance to Ophiomyia phaseoli.The number of viable eggs per plant exhibited significant variation amongst the cultivars studied. No significant differences were found in the developmental period of larvae and pupae or in the size of adults emerging from the cultivars studied. Significant correlations were found between the number of viable eggs per plant and leaf hairiness, stem diameter and internode length. Low egg counts were associated with high leaf hair density, thin stems and long intemodes.

Resistance of Cotton Plant Hairs to Mobility of First-Instars of the Pink Bollworm123

Movements of 1st-instars of pectinophora gossypiella (Saunders) on 6 varieties of cotton with leaves and petioles differing in amount of pubescence were observed, timed, and traced with a camera lucida. The 2 most pubescent varieties, SA-166 and TM-1(H2), appeared to confuse larvae and greatly impeded their movements. We conclude that high plant hair density in cotton is a promising mechanism for host plant resistance to the pink bollworm. Larvae paused regularly to head swing and to sample the substrate with their mandibles while moving on leaves and petioles. When leaf neclaries were encountered by larvae, feeding usually occurred.