Guard Hairs Research Articles

Sexual Differences in Hair Morphology of Coyote and White-Tailed Deer: Males have Thicker Hair

The fur of mammals serves many functions, including thermoregulation, camouflage or visual signaling to conspecifics. Fine-scale features of fur, such as hair morphology are often examined by researchers, especially in animals where pelage is of economic importance. Certain studies from this literature body show that males of many species appear to have thicker guard hair than females. Here, we examined this possibility in coyote (Canis latrans) and white tailed deer (Odocoileus virginianus) from captive populations in Utah and Georgia, USA. We used image analysis procedures to examine 402 guard hairs from 24 captive coyotes and 568 guard hairs from 29 captive deer, measuring the length and diameter of each hair. In both species, males had significantly thicker hairs than females; in coyotes, male hairs were 17% thicker, in deer, male hairs were 15% thicker. These differences are comparable to other species, where male hair is between 7%–20% thicker than those of females (in all species the average differ...

Feeding ecology of carnivores (Mammalia, Carnivora) in Atlantic Forest remnants, Southern Brazil

The diet of some sympatric carnivore species in three Atlantic Forest remnants of Southern Brazil was studied in order to assess their food niche. We conducted monthly field trips between February 2003 and January 2004 to collect fecal samples that were subsequently examined together with others collected sporadically between November 1994 and January 2003. Of the 416 samples analysed, 198 had the "author" species identified through microscopic analysis guard hairs, which revealed the presence of 10 carnivores and some information about their diet. Puma yagouaroundi had the largest dietary niche breadth, whereas Leopardus tigrinus and Nasua nasua showed the lowest values. Extensive niche overlap was observed between L. tigrinus and N. nasua, L. tigrinus and L. wiedii, and between L. tigrinus and L. pardalis. Data presented here not only increases the understanding of carnivore feeding ecology, but also contributes towards their conservation in the study region and other fragmented landscapes in Brazil and neighboring countries.

Morphology and ultrastructure of antler velvet hair and body hair from red deer (Cervus elaphus)

We provide a detailed description of the ultrastructure of deer hair fibers. Guard hairs and underhairs from the winter coat of red deer (Cervus elaphus), and antler velvet hairs from the same species were examined. All fibers displayed the typical keratin fiber morphology of overlapping cuticle cells surrounding a core of cortex cells, and often a centrally-located medulla, but there were considerable differences in the diameter, cuticle thickness, and scale pattern, and in the relative amounts of cortex and medulla along individual fibers, and between the different types of fiber. In addition, closer examination of cortex cells using transmission electron microscopy revealed considerable differences in the arrangement of intermediate filaments in the different fiber types. Fine underhairs appeared similar to fine wool fibers from sheep because intermediate filament arrangements were very similar to those found in wool orthocortex cells and paracortex cells. In addition, a similar bilateral distribution of these cell types was evident. However, in the antler velvet hairs and the guard hairs, intermediate filament arrangements were more variable and complex, and showed similarities to those in heterotype cortex cells described for human hair.

Identification of dorsal guard hair of seven species of the family cercopithecidae (Primates: mammalia)

Dorsal guard hair of the Cercopithecid mammals viz. Macaca fascicularis, M. nemestrina, M. silenus, M. radiata, M. mulatta, M. assamensis, and M. arctoides have been studied by the help of Light microscope. The characteristic features like transverse section, scale pattern and margin, scale margin distance, scale count, medullary configuration, medullary index, side to side cuticular scale length, and proximodistal cuticular scale length of hair provided key to identify concerned species correctly.

Hair cortisol concentration as a noninvasive measure of long-term stress in free-ranging grizzly bears (Ursus arctos): considerations with implications for other wildlife

Human-caused landscape change negatively affects the sustainability of many wildlife populations. In Alberta, Canada, grizzly bears ( Ursus arctos L., 1758) live in one of the most populated and heavily exploited landscapes in which the species survives. Long-term physiological stress in individual animals may be the predominant mechanism linking landscape change with impaired wildlife population health. Hair cortisol concentration has been validated as a biomarker of long-term stress in humans and domestic animals; however, limited work has examined factors that may affect its measurement or interpretation. We have measured cortisol in as few as five guard hairs of a grizzly bear and have identified factors influencing hair cortisol concentration in this species. Hair cortisol varies with hair type, body region, and capture method. It is not influenced by colour, age, sex, environmental exposure (18 days), or prolonged laboratory storage (>1 year) and does not vary along the length of the hair shaft. Recommendations for prudent use of hair cortisol analysis in grizzly bears are discussed with implications for the development of hair cortisol concentration as a tool to monitor long-term stress in other wildlife.

日本産食虫目の体毛の型, とくに直毛 (刺毛) の存在について

日本産食虫目の体毛の型, とくに直毛 (刺毛) の存在について

GENETIC EVALUATION OF FUR TRAITS IN NEW ZEALAND WHITE AND CALIFORNIAN RABBITS RAISED ON HIGH AMBIENT TEMPERATURE

An experiment on New Zealand White (NZW) and Californian (CAL) rabbits was carried out to evaluate genetically post­weaning coat traits of these two breeds raised under hot conditions. Data on 24680 and 10549 fibers collected from 1234 NZW and 520 CAL weaned rabbits were used, respectively. At 8 and 12 weeks of age, post-weaning coat traits included average hair length in cm (HL), hair diameter (µm) in down hair (HDD) and guard hair (HDG), medulla diameter (µm) in down hair (MDD) and guard hair (MDG), and medullation percent in down hair (PMD) and guard hair (PMG). Variance components and sire heritabilities were estimated for these traits using Restricted Maximum Likelihood (REML) procedure. Transmitting abilities (TA) for these traits were estimated using a single­trait Animal Model (AM).Most postweaning coat traits in CAL were slightly higher than those in NZW. The estimates at 8 and 12 weeks, respectively were 2.4 and 3.0 cm in NZW vs 2.4 and 3.1 cm in CAL for HL, 12.2 and 18.8 µm in NZW vs 12.2 and 18.9 µm in CAL for HDD, 62.1 and 89.1 µm in NZW vs 62.3 and 88.9 µm in CAL for HDG, 10.2 and 16.4 µm in NZW vs 10.2 and 16.4 µm in CAL for MDD, 51.4 and 78.1 µm in NZW vs 51.5 and 77.8 µm in CAL for MDG, 82.2 and 87.1 % in NZW vs 83.5 and 86.3 % in CAL for PMD, and 82.2 and 87.4 % in NZW vs 82.6 and 80.5 % in CAL for PMG. Percentages of phenotypic variation in NZW and CAL for coat traits at earlier ages were slightly higher than at older ages with exception of HL. Except HL and HDD in both breeds, sire heritabilities for coat traits were low or somewhat moderate. Heritabilities for all coat traits in CAL rabbits at 8 and 12 weeks of age were higher than in NZW: 0.667 and 0.775 in CAL vs 0.357 and 0.392 in NZW for HL, 0.326 and 0.304 in CAL vs 0.401 and 0.246 in NZW for HDD, 0.051 and 0.142 in CAL vs 0.053 and 0.116 in NZW for HDG, 0.046 and 0.356 in CAL vs 0.053 and 0.075 for MDD, 0.058 and 0.174 in CAL vs 0.057 and 0.119 in NZW for MDG, 0.008 and 0.132 in CAL vs 0.052 and 0.031 in NZW for PMD and 0.074 and 0.047 in CAL vs 0.055 and 0.048 in NZW for PMG. The largest differences in TA for most coat traits were recorded in CAL breed and the lowest differences were observed in NZW. In favor of CAL breed at 12 weeks of age, there was a large range in TA between NZW and CAL rabbits with a difference of 2.474 cm for HL, 0.755 µm for HDD, 0.906 µm for HDG, 0.818 µm for MDD, 1.181 µm for MDG, and 1.5 % for PMO. Among coat traits, the largest percent of positive TA was recorded for HDD followed by HL, MDD and MDG, while the lowest percent was recorded for HDG.

Thermoanalytical characterisation of dromedary hair

The aim of this study is to characterise the fine structure of dromedary hair. Using differential scanning calorimetry (DSC) for temperatures up to 180°C, the denaturation transition of the α-helical material of under and guard hair of dromedaries of various ages in excess water was studied. Also, fine fibre samples of a 5-year-old dromedary were investigated using analytical transmission electron microscopy (TEM). Results show that dromedary hair, wool, and some other animal fibres present a classical bilateral structure where the arrangement of ortho- and para-cortex in fibre cross-section is like wool. This is confirmed from the DSC analysis for dromedary fibres, which show a bimodal melting peak. DSC traces show quite a difference between the two types of fibres contained in dromedary fleeces. Indeed, down and guard hair dromedary fibres present different ortho-cortex denaturation temperatures around 120–140°C, respectively, and may have the same para-cortex denaturation temperature in the range of 145°C. The denaturation enthalpy of guard hair (36 J/g) was found to be higher than that of under hair (12 J/g). This probably explains the greater difference in mechanical characteristics between the two types of fibres. The same conclusion is found for fibres from dromedaries of various ages. In fact, the denaturation enthalpy of under hair increases with the dromedary age, the minimum being 11 J/g and the maximum 16 J/g for 1-year-old and 19-year-old dromedaries, respectively.

β-catenin Activity in the Dermal Papilla Regulates Morphogenesis and Regeneration of Hair

The activity of keratinocytes in the hair follicle is regulated by signals from a specialized mesenchymal niche, the dermal papilla (DP). Here, mice expressing cre recombinase in the DP were developed to probe the interaction between follicular keratinocytes and the DP in vivo. Inactivation of the beta-catenin gene within DP of fully developed hair follicles results in dramatically reduced proliferation of the progenitors and their progeny that generate the hair shaft, and, subsequently, premature induction of the destructive phase of the hair cycle. It also prevents regeneration of the cycling follicle from stem cells. Gene expression analysis reveals that beta-catenin activity in the DP regulates signaling pathways, including FGF and IGF, that can mediate the DP's inductive effects. This study reveals a signaling loop that employs Wnt/beta-catenin signaling in both epithelial progenitor cells and their mesenchymal niche to govern and coordinate the interactions between these compartments to guide hair morphogenesis.

Effects of nutrition and origin on the amino acid, grease, and suint composition and color of cashmere and guard hairs

AbstractNutritional and environmental effects on the amino acid, wax, and suint contents and color of raw cashmere were investigated. Cashmere was obtained from goats fed with or without dietary protected protein, goats fed different levels of dietary energy and feeds, and goats from Australia, China, and Iran. The determined attributes included the production, diameter, length, fiber curvature, crimp, wax and suint contents, amino acid composition, lightness, and yellowness of cashmere. The content of suint, but not that of wax, was affected by nutrition management. The amino acid composition of cashmere was affected by the energy and protein nutrition, feed type, and country of origin. The amino acid composition of cashmere was different from that of guard hair. The lightness and yellowness of cashmere was affected by the nutrition treatment, grazing, cashmere production, and sum of the wax and suint contents of the raw cashmere. The variation in the amino acid composition of cashmere likely affected both its physical and chemical reactivity. Nutrition manipulation of cashmere goats and the origin of goats have implications with respect to the properties of cashmere as changes in fiber cell biosynthesis can alter the amino acid composition of the fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Abundance of wild prey modulates consumption of supplementary food in the Iberian lynx

Food supplementation is increasingly used as a conservation tool. However, little is known about how much supplemental food is used by target populations or the degree to which the abundance of natural food affects the utilization of supplemental food. Long-term supplementation programmes could cause individuals to rely almost exclusively upon supplemental food and, consequently, lose some skills needed to forage efficiently on natural food. This may result in reduced fitness upon discontinuation of supplemental food. The Iberian lynx ( Lynx pardinus) preys almost exclusively upon European wild rabbits ( Oryctolagus cuniculus), and some populations are thought to be food limited. We quantified the contribution of supplemented domestic rabbits, whose guard hairs could be distinguished from hairs of wild rabbits, to the diet of the Iberian lynx. We also examined whether the consumption of domestic rabbits varied with the availability of wild rabbits, and with the duration of exposure to supplemental food. Domestic rabbits made up over 50% of the diet. Consumption of domestic rabbits decreased non-linearly as the relative abundance of wild rabbits increased; however, this pattern was true only above a threshold density of one wild rabbit km −1. Below this threshold, supplementation was apparently strictly necessary to retain Iberian lynx. The consumption of domestic rabbits did not increase with the length of the supplementation period. Lynx continued consuming wild rabbits proportionally to their abundance, suggesting lynx did not become dependent upon supplemental food. Understanding how the abundance of natural food modulates consumption of supplemental food may help to adjust supplementation schedules to food availability and to the needs of the target populations.

Current understanding of Merkel cells, touch reception and the skin

Merkel nerve endings are found in human skin, as well as the skin of all vertebrates functioning as mechanoreceptors. Merkel cells are located in the basal layer of the epidermis both in hairy and in glabrous skin, and are often arranged in clusters. In hairy skin, Merkel cells are typically associated with large guard hairs and specialized sensory complexes known as touch domes. Merkel cells have lobulated nuclei and dense-core granules in the cytoplasm facing the associated afferent nerve terminal. Developmental studies have shown that avian Merkel cells are derived from the neural crest. In mammals, studies on transgenic mice have resulted in contradictory findings. Thus, the question of the developmental origin of mammalian Merkel cells remains to be resolved. Functionally, mammalian Merkel cell nerve endings are slowly adapting mechanoreceptors. In response to maintained mechanical stimulation they keep firing action potentials with characteristic irregular patterns. New experimental evidence strongl...

Relationships between integumental characteristics and thermoregulation in South American camelids

Hair fibre is regarded as a unique mammalian feature with an important role for endothermy. Artificial selection for hair characteristics resulted in marked changes with regard to follicle number, type, distribution, growth and natural shedding. This review focuses on the fine fibre-producing South American camelids (SACs) and the relationship between their hair coat and thermoregulation. SACs have developed several special integumental characteristics. While the hair coat of the wild lamoids vicuña (Vicugna vicugna) and guanaco (Lama guanicoe) is formed by two types of hair (the coarse outer guard hairs and a finer undercoat), the domesticated llamas (Lama glama) and alpaca (Lama pacos) exhibit variably double coat and predominantly single coat, respectively. The distribution of the hair coat across the body is not homogenous. Thermal windows with shorter hair or thinner skin can be identified at the ventral abdomen, axillary space and inside of the thighs (about 20% of the skin), thus allowing to modulate heat dissipation. In contrast to sheep wool, lamoid fibres are mainly medullated. The thermal conductance of summer pelage was higher than that of the winter fleece and highest for the axillar and lower flanks. Lamoids have developed behavioural strategies to modify heat loss by adopting specific postures according to ambient conditions by closing or opening the thermal windows. Energy savings of 67% attributed to posture were calculated. SACs have shown to be able to adapt to a broad range of different climatic conditions. The specific integumental characteristics of SACs indicate that they have developed adaptation mechanisms particularly suited for cooler climates. Accordingly, hyperthermia might become a problem in hot, humid areas outside of their original habitat. Several studies showed the beneficial effect of shearing against heat stress. In particular, fertility in males exposed to heat stress may be improved by shearing. Infrared thermography reveals that in shorn animals the heat is radiated across the entire body surface and is not restricted to the thermal windows. However, shearing also changes the conditions of the protective layer, resulting in a loss of thermal conductance that may result in adverse effects when animals are kept under cold temperatures. The length of residual fibre appears to be crucial in avoiding excessive heat loss in a cold environment, as demonstrated by shearing experiments with different shearing machines. There is, therefore, potential for welfare considerations to conflict with industrial demands for fibre length or homogenous quality.

Environmental Factors Affecting Fleece Traits in Raeini Cashmere Goat

The objective of this study was to evaluate some environmental factors (sex, age and management system) on fibrecharacteristics of Raeini Cashmere goats in Baft stations (BS) and of Raeini Cashmere goats raised in nomadic conditions (NC) as commercial flocks. Fiber samples including cashmere and hair were taken from 150 and 120 Raeini Cashmere goats (aged 1-8 years old) from BS and NC, respectively. The Fleece traits measured included staple length (SL), percentage of cashmere in fleece (C), percentage of guard hair in fleece (H), cashmere's mean fiber diameter (CMFD) and the coefficient of variation of cashmere's fiber diameter (CVFD). Mean SL, C, H, CMFD and CVFD in BS were 6.35 ±0.1 cm, 66.51± 0.72 %, 33.5 ± 0.72 %, 20.19 ±0.11 micron and 19.57± 0.21% and thosein NC were 5.62 ± 0.1 cm, 69.06 ± 0.74 %, 30.94 ±0.74 %, 19.53±0.15 micron and 17.88 ± 0.19 %, respectively. There were significant differences (P<0.05) between the two production management systems for all traits investigated. The value for C was significantly higher in males than females (P<0.05). The results showed that the fleece traits were affected by age. However, the effect of age on these traits was not the same. Significant phenotypic correlations were found between SL and CMFD (0.16) and between SL and CVFD (0.13). The results of this study indicated that the fixed effects of age, sex and management systems as well as the relationship between fleece traits should be considered in the Raeini Cashmere goat breeding programs.

Forensic hair analysis to identify animal species on a case of pet animal abuse

As part of an investigation of a case of pet animal abuse, we attempted to identify small mammalian species by morphological analysis and single-nucleotide polymorphism (SNP) typing of the cytochrome b gene using guard hairs as an analytical material. Guard hair samples from several species were measured for length, width, medulla formation, and cuticle scale pattern under a light microscope or scanning electron microscope. These samples were also analyzed for SNPs in the cytochrome b gene using a multiplex single-base primer extension reaction. Morphological analysis of cuticle scale pattern and medulla formation was able to discriminate ferret hairs from other hair samples that included rabbit, gerbil, degu, and Djungarian hamster. However, this also revealed a similarity of the guard hairs of the ferret (Mustela putorius furo) and Japanese weasel (Mustela itatsi). Although at three sites, the nucleotide color signals of SNPs in the cytochrome b gene could be used to discriminate completely among human, dog, and gerbil, the signals for cat, ferret, and Japanese weasel occurred at the same nucleotide sites. Unfortunately, no signals were obtained from degu, Djungarian hamster, and rabbit hairs. Although the discriminated hair samples were 100% identical to those of the ferret, there was only a 5% difference from Japanese weasel in the partial sequence of the cytochrome b gene. Construction of a database of mammalian hairs would be useful not only in forensic science, but also for investigating smuggling of endangered species in contravention of the Washington Convention.

Identification of a forensic case using microscopy and forensically informative nucleotide sequencing (FINS): A case study of small Indian civet (Viverricula indica)

The exhibits obtained in wildlife offence cases quite often present a challenging situation for the forensic expert. The selection of proper approach for analysis is vital for a successful analysis. A generalised forensic analysis approach should proceed from the use of non-destructive techniques (morphological and microscopic examination) to partially destructive and finally destructive techniques (DNA analysis). The findings of non-destructive techniques may sometime be inconclusive but they definitely help in steering further forensic analysis in a proper direction. We describe a recent case where a very small dried skin piece (<0.05 mg) with just one small trimmed guard hair (0.4 cm) on it was received for species identification. The single guard hair was examined microscopically to get an indication of the type of species. We also describe the extraction procedure with a lower amount of sample, using an automated extraction method (Qiagen Biorobot EZ1) and PCR amplification of three mitochondrial genes (16s rRNA, 12s rRNA and cytochrome b) for species identification. Microscopic examination of the single hair indicated a viverrid species but the initial DNA analysis with 16s rRNA (through NCBI BLAST) showed the highest homology (93%) with a hyaenid species (Hyaena hyaena). However, further DNA analysis based on 12s rRNA and cytochrome b gene proved that the species was indeed a viverrid i.e. Viverricula indica (small Indian civet). The highest homology shown with a Hyaenid species by the 16s rRNA sequence from the case sample was due to lack of a 16s rRNA sequence for Viverricula indica in the NCBI data base. The case highlights the importance of morphological and microscopic examinations in wildlife offence cases. With respect to DNA extraction technology we found that automatic extraction method of Biorobot EZ1 (Qiagen) is quite useful with less amount of sample (much below recommended amount).

Seasonal Metabolic Acclimatization in a Northern Population of Free-Ranging Snowshoe Hares,Lepus americanus

Seasonal acclimatization in high-latitude endotherms may involve increases or reductions in body size and metabolic rate to, respectively, augment thermoregulatory capacity or reduce energy requirements. We investigated seasonal acclimatization in a northern population of wild snowshoe hares (Lepus americanus) that is exposed to low food availability and extremely cold temperatures in winter. Snowshoe hares were livetrapped and transported to a nearby mobile laboratory. Hares were placed in a metabolic chamber and oxygen consumption was measured for 55 min at each of the following temperatures: 10uC, 0uC, 210uC, 215uC, and 220uC. Hair length and density were measured on a sample of collected hares. Snowshoe hares maintained similar body mass and body temperature between the seasons, but average resting metabolic rate and thermal conductance were, respectively, 20% and 32% lower in winter than in autumn. The lower critical temperature was 210u Ct o215uC in winter and 0u Ct o210uC in autumn. Guard hairs were 36% longer and 148% denser in winter than autumn, whereas downy hairs were the same length but 128% denser in winter than autumn. Collectively, these results suggest that resource constraints associated with a herbivorous diet in regions and seasons of poor forage quality favors an energetically conservative approach to winter acclimatization.

Microscopic hair characteristics of a few bovid species listed under Schedule-I of Wildlife (Protection) Act 1972 of India

Dorsal guard hairs of 10 bovid species of India, listed under Schedule-I of Wildlife (Protection) Act 1972 of India and some of them quite frequently encountered in illegal trade, were studied using light microscopy. We discuss characteristics including colour, hair thickness, cuticular pattern, medulla pattern, medulla index, cross-section and scale count index for species characterisation/identification to deal wildlife offence cases. Although some species could be identified very easily based on one or few microscopic hair characteristics, however there were some overlaps of few hair characteristics among some species. Species like Pantholops hodgsonii could be characterised most easily, just based on cuticular pattern and similarly Capricornis sumatraensis could be characterised simply by medulla pattern. For species showing overlaps in some of the microscopic hair characteristics, a combination of all the characteristics was most useful. We suggest the use of maximum number of parameters for distinguishing sympatric and closely related species. In addition to wild species, hair characteristics of three domestic species have been examined and compared with the selected wild species.

Maternal methyl supplements affect the phenotypic variation of the agouti gene in the offspring of rats with different behavioral types

The effects of selection of agouti rats (with genotype AAHH) on the tame and aggressive behavior and dietary methyl given to females from the eighth day of pregnancy to the fifth day after the birth of the offspring on the intensity of the agouti coat color in the offspring have been studied. The morphometric parameters of hair determining the darkness of the agouti color (the total length of guard hairs, the lengths of their eumelanin end and pheomelanin band, the ratio between the lengths of the eumelanin and pheomelanin portions of the hair, the total length of the awn hairs, and the relative length of their widened “lanceolate” upper end) have been compared. It has been found that selection of agouti rats for aggressive behavior is accompanied by darkening of the coat color compared to tame rats due to an increase in the ratio of the length of the black eumelanin end of the guard hairs to the length of the yellow pheomelanin band. Methyl-containing additives to the diet of females affect the intensity of the agouti coat color in the offsprings with both types of behavior, but to different extents. Aggressive offspring is more sensitive to the mother’s methyl-containing diet: the percentage of animals that are darker than control rats is higher among aggressive animals than among tame ones due to a greater increase in the ratio between dark and light portions of hairs. The possible mechanisms of differences in the phenotypic modifications of coat color in control and experimental agouti rats with different types of behavior are discussed.

Analysis of the Temporal Requirement for Eda in Hair and Sweat Gland Development

EDA signaling is important in skin appendage initiation. Its possible involvement in appendage subtype determination and postinduction stage appendage development, however, has not been studied systematically. To address these issues we manipulated Eda-A1 transgene expression in a tetracycline-regulated conditional mouse model, where the transgene is the only source of active ectodysplasin (Eda). We find that Eda-A1 restores sweat glands and all hair subtypes in Tabby, but each requires its action at an idiosyncratic time of development: by E17 for guard, by E19 for awl, and starting at E18 for zigzag/auchen hair. Guard and awl hairs were indistinguishable from their wild-type counterparts; but restored zigzag and auchen hairs, although recognizable, were somewhat smaller and lacked characteristic bends. Notably, secondary hair follicle formation of awl, auchen, and zigzag hairs required higher Eda-A1 expression level than did guard hair or sweat glands. Furthermore, Eda-A1 expression is required until the early dermal papilla stage for guard hair germs to make follicles, but is dispensable for their maturation. Similarly, sweat gland pegs require Eda-A1 at an early stage to form mature glands. Thus we infer that EDA signaling is needed for the determination and development of various skin appendages at spatiotemporally restricted intervals.