Surface Of Integument Research Articles

Can Bergmann’s Rule and the Thermal Melanism Hypothesis explain the variation in colour and size observed in the wild bee Eoanthidium insulare (Apoidea: Megachilidae) across its Palaearctic range?

To analyse geographic variation patterns and assess the applicability of biogeographical rules in insects, the West Palaearctic anthidiine bee Eoanthidium insulare serves as an excellent model. This species showcases a highly variable black-and-yellow colour pattern, with a distribution spanning over 4400 km from the Adriatic Sea to the Pamir Mountains and extending over 1660 km in a south-north direction. We examined 214 specimens from all geographic regions of its distribution and identified a significant increase in both body size and the proportion of black in the integument from south to north. This phenomenon may be attributed to a more efficient exploitation of solar energy through a larger integument surface area (Bergmann’s Rule) and enhanced heat retention due to lower skin reflectance (Thermal Melanism Hypothesis). These two processes, therefore, complement each other. However, despite the cooler climates at higher altitudes, we found no correlations between body size and altitude. Furthermore, while we observed an increase in the proportion of black in the integument from east to west, there was no significant increase in body size. Notably, no correlation between body size and body colouration was identified, suggesting that size and colour adaptation are independent processes. Given that the various colour and size patterns were identified as clinal rather than discontinuous, and the intraspecific genetic distance across the distribution area was remarkably low (0.00138), featuring only four distinct haplotypes of the mitochondrial COI region DNA sequence, we suggest that the subspecies E. i. persicolum and E. i. lemesium be regarded as synonymous with the nominate subspecies (syn. nov.). These findings suggest that, although Bergmann’s Rule and the Thermal Melanism Hypothesis can account for certain aspects of geographic variation in the body size and colouration of E. insulare, their effects may be influenced or superimposed by factors such as genetic constitution.

Survival of immature pre-adult Gnathostoma spinigerum in humans after treatment with albendazole

Human gnathostomiasis is a food-borne zoonotic helminthic infection widely reported in Latin America, Asia and Southeast Asia, particularly in Thailand. There are increasing reports of the parasite in countries where it is not endemic. A study of the survival drug-treated immature stage (STIM) of Gnathostoma spinigerum recovered from infected patients focused on their integument surface using scanning electron microscopy (SEM). STIM displayed a specific, characteristic head bulb, with a pair of large thick equal-sized trilobulated lips in the centre. Cephalic spines had eight transverse rows on the head bulb with single-ended tips curved posteriorly. Body cuticular spines on the anterior half of the STIM were not sharp-pointed but distributed more densely, with multi-dentated-cuticular spines, irregularly arranged in a lining pattern of velvety cuticular folds. The length of cuticular spines increased caudally. The size of spines became gradually smaller, and numbers decreased towards the posterior end. Spines were still widely dispersed posteriorly as their density dropped. The morphology of STIM of G. spinigerum are described in detail for the first time. These specimens showed structural adaptation based on changes on integument surfaces, probably to protect against damage induced by the toxic effects of albendazole.

The bioactive compound carvacrol as a potential acaricide: An assessment of its effects on the integument of female Rhipicephalus sanguineus sensu lato ticks.

Studies seeking control methods for infestation of Riphicephalus sanguineus sensu lato (s.l.) ticks (dog ticks) have been carried out in order to minimize damage to both the tick's hosts and the environment, the latter due to the misuse of acaricide products. In this regard, carvacrol has been used as a natural alternative against ticks as it displays several properties including acaricidal. In this context, the present study aimed to evaluate the ultramorphology and morphohistochemistry of the integument of semi-engorged R. sanguineus s.l. females exposed to different carvacrol concentrations. The findings indicate that the integument surface of females exposed to the highest carvacrol concentration (25 μl/ml) became wrinkled, suggesting dehydration or the result of integument cuticular and epithelial layer disorganization in response to the toxic product. Morphohistochemical integument layer alterations were more significant and intense in females exposed to the highest carvacrol concentration (25 μl/ml), confirming dose-dependent carvacrol action. Among other cell and tissue alterations, changes in epithelial cell shape, size, and arrangement (epidermal layer) were noted, alongside altered and pyknotic-shaped nuclei, suggesting a death process for these cells. This epithelium changed from simple cubic to stratified, also in response to the presence of the evaluated bioactive compound. Thus, the findings reported herein demonstrate that carvacrol may be an alternative for an efficient and more sustainable tick control in the near future.

The water path in plasma-treatedLeucaenaseeds

AbstractThe effects of cold atmospheric plasma (CAP) of dielectric barrier discharges on the wettability, imbibition and germination ofLeucaena leucocephalawere investigated. It was established that CAP treatment markedly hydrophilized the seed coat, especially at longer treatment times. From the profile of the imbibition curve and visual observation, it was possible to verify that there are two resistance barriers to water penetration: integument surface and region of the macrosclereid cell wall (light line). Although the plasma interacts only in the integument, increasing the density of hydrophilic sites increases the capacity of water absorption, producing enough driving force to overcome the second resistance barrier. The existence of these two barriers changes the three-phase pattern generally observed during seed germination. Despite an increase in imbibition, the plasma treatment conditions used in this work, were not enough to overcome completely the dormancy barrier.

BgFas1: A fatty acid synthase gene required for both hydrocarbon and cuticular fatty acid biosynthesis in the German cockroach, Blattella germanica (L.)

Insect cuticular hydrocarbons (CHCs), the evolutionary products of aquatic hexapod ancestors expanding to terrestrial environment, are deposited on the surface of insect integument and originally functioned primarily as waterproofing agents. CHCs are derived from the conserved fatty acid synthesis pathway in insects. However, the pivotal fatty acid synthase (FAS) involved in hydrocarbon (HC) biosynthesis remains unknown in many insect orders including the primitive Blattodea. Here, we investigated functional FAS genes that modulate cuticular lipid biogenesis in the German cockroach, Blattella germanica (L.). Based on our full-length transcriptomic data and the available genomic data, seven FAS genes (BgFas1–7) were identified from B. germanica. Tissue-specific expression analysis revealed that BgFas1, BgFas3, BgFas4 and BgFas7 were highly expressed in the integument, whereas BgFas2 was dominantly expressed in the fat body. BgFas5/6 mRNA was almost negligible in the tested tissues. Systemic RNAi screen was performed against BgFas1–7, we found that only RNAi knockdown of BgFas1 caused a dramatic reduction of methyl-branched HCs (mbHCs) and a slight decrease of straight-chain HCs (scHCs) for both internal and external HCs. Significant reduction of cuticular free fatty acids (cFFAs) was also detected within BgFas1-repressed cockroaches, while repression of CYP4G19 resulted in dramatic increase of cFFAs. Moreover, we found that BgFas1 mRNA levels were correlated with insect molting cycles, and could be induced by long-term mild dryness treatment. Furthermore, desiccation assay revealed that BgFas1 suppression accelerated water loss and led to early death of cockroaches under desiccation. Our results indicate that BgFas1 is necessary for both HC and cFFA biosynthesis in B. germanica. In addition, our study also confirms that cuticular lipids, particularly mbCHCs, are critical for desiccation resistance in B. germanica.

Prevalence, site of infection, and differentiating oocytes of the cymothoid isopod, Norileca indica (Milne Edwards, 1840) from its infected short mackerel, Rastrelliger brachysoma, in the Upper Gulf of Thailand

Norileca indica, a cymothoid isopod crustacean, is an obligate parasite infecting marine fishes in tropical areas. This study attempted to investigate the prevalence, site of infection and distinct stages of oogenesis of this parasitic isopod obtained from short mackerel (Rastrelliger bachysoma). All N. indica samples were collected and processed through histological techniques. N. indica showed higher prevalence during the dry season than the rainy season and its parasitic infections were more prevalent in the female R. brachysoma (60% prevalence) compared to males. Two distinct sites of N. indica attachment on the host (infection sites) including gill and integument were clearly observed. Interestingly, this isopod preferred to attach more on the integument surface than gill, especially in the female R. brachysoma (55% prevalence). Using histological observation, N. indica exhibited asynchronous development of oocyte in the ovary. The oocytes were enclosed by a thin layer of connective and muscular tissues. Three stages of oogenesis can be identified in the ovary: oogonium, primary oocyte, and secondary oocyte. Oogonium located inside the cyst near the germinal epithelium. A large nucleus of oogonium was surrounded by a weak basophilic cytoplasm. Unlike oogonium, multiple nuclei (2 - 3 nuclei) surrounded by basophilic cytoplasm was a key characteristic of the primary oocyte. The secondary oocyte contained spherical yolk granules with multiple layers of follicular cells, which might function to support yolk uptake into the ooplasm. In addition, early embryonic development of N. indica was also observed in this study. Taken together, this finding highlights parasitic prevalence and infection sites of N. indica in short mackerel, as well as a better resolution of its oogenesis, early development and reproductive cycle.

The integument of the nonamphibious goby Gobionellus oceanicus: Its functional morphology and respiratory capacity.

Facultative air-breathing fish can exchange respiratory gases using an air-breathing organ (ABO), such as the oral cavity of the integument, during environmental hypoxia. The goby Gobionellus oceanicus inhabits areas subject to environmental hypoxia; however, its ABO is unknown. To investigate the respiratory potential of G. oceanicus, the gill and integument surface area, diffusion capacity, and their diffusion barrier thickness were measured. Our results show that although gill surface area is smaller than observed in other facultative air-breathing fish, but it has all features necessary to perform aquatic gas exchange. Additionally the integument of the palate has a short diffusion barrier thickness and a large calculated O2 -diffusion capacity suggesting that it functions as the ABO.

Outbreak of Infection by Piscinoodinium pillulare and Trichodina spp. in Tambaquis (Colossoma macropomu), Pirapitingas (Piaractus brachypomus) and Tilapias (Oreochromis niloticus) in the Federal District, Brazil

Background: Piscinoodinium pillulare is a mandatory mastigophore protozoan with no parasitic specificity, and an important ectoparasite of tropical and temperate psiculture. This parasite is responsible for serious health problems in Brazilian native fish. Another important pathogenic protozoan in psciculture belongs to the genus Trichodina spp., which is commonly found on the surface of fish, gills, fins, and integument. The aim of the present study was to describe an outbreak of P. pillulare andTrichodina spp. in three species of fish intensively created, emphasizing the anatomopathological and epidemiological aspects.Cases: Five animals were necropsied, among them three tambaquis (Colossoma macropomu), one pirapitinga (Piaractus brachypomus) and one tilapia (Oreochromis niloticus) from an intensive psciculture in the Federal District. Out of 1500 fishes, 18 (1.2%) became ill and died. It was reported that the animals showed decreased feed intake, discomfort, dyspnea, opercular movements, red skin lesions and consequent death. In the direct examination of scraping of the body surface of a fish, preparedbetween lamina and coverslip, a ciliated ectoparasite, with a circular bell shape, measuring approximately 20-180 μm, adhered, with morphology consistent with Trichodina spp. was evidenced. During necropsy, fragments of different organs were collected and fixed in 10% formalin, routinely processed for histology, embedded in paraffin, cut to five microns thick and stained with hematoxylin and eosin (HE). Macroscopically, there were pale scaly areas in the medial-lateral regions, moderate increase amountof mucus with brown to green lumps on the body surface, partial loss of the fins, swollen gills with whitish mucus and multifocal hemorrhagic areas on the skin and between the scales. Microscopically, moderate multifocal lymphoplasmocytic branchitis was observed with cell hyperplasia and fusion of secondary lamellae associated with trophons (protozoa), consistent with P. pillulare.Discussion: The diagnosis of infection by P. pillulare and Trichodina spp. in this study was based on the epidemiological and clinical-pathological findings. Regarding the first ones, we highlight the variety of fish species affected. P. pillulare is an example of a commensal parasite present on the substrate of culture tanks, and exerts a type of non-obligatory parasitism that uses the fish as a substrate for its fixation under favorable conditions. In this case, only Trichodina spp. was observed during the traditional evaluation of body surface and gills scraping, and histopathology was essential for the verification of the agent P. pillulare. Routine histopathological analysis may also provide a definitive diagnosis, observing the trophons attached to the gill filaments. Atrophy and fusion of secondary lamellae, which promote proliferative lesions in the gills associated with the interlamellar presence of parasites, are responsible for hypoxia, loss of balance and erratic movements. Although they were observed in a small number, Trichodina spp. are believed to be responsible, on a larger scale, for hemorrhagic lesions on the skin and between fish scales. These findings were similar to those of the literature, and the diagnosis of these parasites allows producers and technicians to adopt adequate treatment, as well as prophylactic measures that provide good environmental conditions in order to avoid economic losses.Keywords: fish diseases, protozoa, fish ectoparasites.

Morphology of the Nymphs ofEuschistus convergens(Hemiptera: Pentatomidae)

Abstract Nymphs of Euschistus (Mitripus) convergens (Herrich-Schaffer) (Hemiptera: Pentatomidae) are described using light and scanning electron microscopy. In the 1st instar, the integument and the lateral margins of the body are smooth, the dorsal abdominal scent glands bear a rounded peritreme with cuticular valve, and the evaporatorium surface bears pointed projections. From the 2nd to the 5th instars, the integument surface is granulated, the lateral margins of the body are serrated, the dorsal abdominal scent glands bear a spout-shaped peritreme with a cuticular valve, and the evaporatorium surface is reticulated. The overall morphology of E. convergens nymphs resembles the morphology of nymphs of other Euschistus species.

Superhydrophobic cuticle with a “pinning effect” in the larvae of the iris sawfly, Rhadinoceraea micans (Hymenoptera, Tenthredinidae)

The integument of some sawfly larvae can be easily damaged causing haemolymph bleeding (easy bleeding phenomenon). In the present study, we investigated intact cuticle, cuticle without wax coverage and cuticle replicas of sawfly larvae by using cryo-scanning electron microscopy and contact angle (CA) measurements. The easy bleeder Rhadinoceraea micans was compared to the non-easy bleeder Nematus pavidus (both Tenthredinidae), and the examination showed that the surface structures of R. micans were hierarchically arranged, whereas the cuticle surface of N. pavidus appeared much smoother. The intact cuticle proved to be superhydrophobic in R. micans (CAs: 156° dorsally, 120° ventrally), but not in N. pavidus (CAs: 67° dorsally, 47° ventrally). The wettability of R. micans increased significantly after the waxes had been peeled off. Replicas of the intact cuticle surface were hardly wettable in both species. It is suggested that wax crystals in combination with cuticle microsculptures are the most important features for rendering the integument of the easy bleeder species superhydrophobic. The wax-free tips of the cuticle microsculptures in R. micans are sites where haemolymph droplets can adhere. The integument surface of easy bleeders is assumed to be adapted to their particular defence strategy, simultaneously contributing to the maintenance and “reuse” of released haemolymph droplets on the superhydrophobic surface due to this “pinning effect”.

Larval morphology and diagnosis of the Giant Microcaddisfly species, Ugandatrichia spp. (Hydroptilidae: Trichoptera) in Thailand

Fifth instar larval morphology and ultrastructure of Ugandatrichia kerdmaung Malicky and Chantaramongkol 1991, U. maliwan Malicky and Chantaramongkol 1991, U. honga Olah 1989 and U. hairanga Olah 1989 were investigated. The Ugandatrichia spp. are case bearing and net spinning caddisflies. The presence, number and characteristics of the sclerites on abdominal sterna III, IV, and V can be used to identify the Ugandatrichia species found in Thailand. The larva of U. honga has no sclerites on the abdominal sterna; that of U. hairanga has a sclerite on each of abdominal sterna III, IV, and V; that of U. kerdmuang has a sclerite on each of abdominal sterna IV and V, and that of U. maliwan has six sclerites on abdominal sterna IV and V. SEM micrographs of Ugandatrichia spp. showed that the spherical palpiger has a labial palp, an anterior silk gland opening, and dense bristles anteriorly and inside of its mouth. There are three main types of integument surface: an irregular dome shape which is found on the head, pronotum, mesonotum, and metanotum; a regular dome shape which is found on the membrane between the nota; and an amoeboid, dot shape which is found on the abdominal segments.

A new species of Valettiopsis Holmes, 1908 (Crustacea: Gammaridea: Lysianassoidea) from abyssal waters off California

Deep-sea sampling off the central California coast has provided numerous material of a new amphipod species of the genus Valettiopsis Holmes, 1908. Valettiopsis concava sp. nov. is described from abyssal collections taken from baited traps and sponge stalk communities. Morphological characteristics which distinguish the new species from its congeners are found in the dorsal profile of the body, integument surface, and shape of coxa 2 and basis of pereopod 7. This contribution presents the second recorded species of the genus Valettiopsis described from the north Pacific, the first being the type species V. dentata Holmes, 1908. The new species is fully illustrated and compared with related species. The generic identity of Valettiopsis ruffoi Serejo & Wakabara, 2003 is discussed. A key to Valettiopsis species is provided.

Development of the entomopathogenic hyphomycete Lecanicillium muscarium (Hyphomycetes: Moniliales) on various hosts

The present scanning electron microscopy study describes the development of Lecanicillium muscarium, strain DAOM 198499, on the surface of diverse hosts, including Sphaerotheca fuliginea, a fungal host, and Macrosiphum euphorbiae and Aphidius nigripes, insect hosts. The hosts were sprayed with a conidial suspension of L. muscarium (107 conidia/ml). The specimens used in the SEM investigation were collected at particular periods after spraying and prepared for scanning using standard methods. Germination tubes developed twenty-four hours after applying L. muscarium conidia to each host. Hyphae were attached to the host by a thin mucilaginous matrix. Seventy-two hours after spraying, hyphae of S. fuliginea had collapsed and were encircled by the parasite, and primary sporulation of L. muscarium was observed. On the aphid host, colonization started with adherence of the conidia to the host cuticle, followed by conidial germination and growth of mycelium on the surface of the insect's integument. After 48 to 72 h, post colonization, the first sporulation was observed on the cuticle, particularly at articulations. The mode of parasitism of A. nigripes by this fungus was similar to that of the aphid. Development of L. muscarium was observed on both mummified aphids (containing the pupae of parasitoids) and adult parasitoids.

Morphology of Bufo ictericus integument (Amphibia, Bufonidae)

Bufo ictericus integument was investigated by stereoscopic, low vacuum scanning electron microscopy, transmission electron microscopy and light microscopy. The studies revealed, that the dorsal integument surface is rougher than ventral. Three types of projections are visualized: larger rounded verrucae, smaller conical cornified tubercles, and conical short spines. Prominent verrucae are observed on the dorsal surface, being flatter on the ventral surface. The tubercles are visualized only on the dorsal surface. The verrucae are separated by grooves that may contribute spreading and retention of the glandular secretion upon the integument. The pattern of the epidermal grooves is also important for water distribution, protecting the animal against desiccation. The epidermis is composed of a stratified epithelium with intraepithelial blood vessels, where keratinocytes predominate, but flask cells, and Merkel cells also occur. In the spongious dermis, cutaneous glands are visualized. The compact dermis is a series of alternating layers of bundles of collagenous fibers, and between spongious and compact dermis there are basophilic areas that correspond to Eberth-Katschenko layer. The dorsal and the ventral surfaces of B. ictericus are morphologically distinct. The integument structure is related to the physiology of each surface and represents an adaptation to habitat, reflecting a lifestyle of the animal.

Surface structure, model and mechanism of an insect integument adapted to be damaged easily

BackgroundSeveral sawfly larvae of the Tenthredinidae (Hymenoptera) are called easy bleeders because their whole body integument, except the head capsule, disrupts very easily at a given spot, under a slight mechanical stress at this spot. The exuding haemolymph droplet acts as a feeding deterrent towards invertebrate predators. The present study aimed to describe the cuticle surface, to consider it from a mechanistic point of view, and to discuss potential consequences of the integument surface in the predator-prey relationships.ResultsThe integument surface of sawfly larvae was investigated by light microscopy (LM) and scanning electron microscopy (SEM) which revealed that the cuticle of easy bleeders was densely covered by what we call "spider-like" microstructures. Such microstructures were not detected in non-easy bleeders. A model by finite elements of the cuticle layer was developed to get an insight into the potential function of the microstructures during easy bleeding. Cuticle parameters (i.e., size of the microstructures and thickness of the epi-versus procuticle) were measured on integument sections and used in the model. A shear force applied on the modelled cuticle surface led to higher stress values when microstructures were present, as compared to a plan surface. Furthermore, by measuring the diameter of a water droplet deposited on sawfly larvae, the integument of several sawfly species was determined as hydrophobic (e.g., more than Teflon®), which was related to the sawfly larvae's ability to bleed easily.ConclusionEasy bleeders show spider-like microstructures on their cuticle surface. It is suggested that these microstructures may facilitate integument disruption as well as render the integument hydrophobic. This latter property would allow the exuding haemolymph to be maintained as a droplet at the integument surface.

SEM AND TEM STUDY OF THE INTEGUMENT OF OPHIOIKA SP. (CRUSTACEA, COPEPODA)

Abstract The ultrastructure of the integument in a parasitic copepod Ophioika sp., which may be a new species, is described using SEM and TEM of specimens both in situ and dissected out of their brittlestar host, Ophiocoma scolopendrina. The parasite is found embedded in host connective tissue at the base of the arm. The surface of the parasite's integument facing the host has knob-like projections, some of which have long microvilli-like endings. Whether these structures have an absorptive function and play a role in the parasite's feeding is discussed.

Postpollination-prezygotic ovular secretions into the micropylar canal inPseudotsuga menziesii (Pinaceae)

Ovular morphology was examined ultrastructurally inPseudotsuga menziesii to determine the effects of the ovule on pollen development. Vesicles containing lipid-like substances traverse cell walls of the inner epidemis of the integument and release their contents at the integument surface to form the integumentary membrane. A major aqueous secretion from the integument into the micropylar canal is proposed to occur by the movement of the integumentary membrane and its invaginations towards the center of the micropylar canal. The cellular degeneration of the nucellar apex results from the breakdown of vacuoles. After this degeneration, electron-dense substances move from the prothallial cells of the female gametophyte towards the nucellus, and many morphological changes in the nucellus, prothallial cells, and micropylar canal take place simultaneously. We interpret these changes to result from another major secretion from the prothallial cells. Egg cytoplasm appears to disorganize for a short time. Simultaneously, substantial amounts of electron dense-substances in the prothallial cells and lipid-like substances in surface cell walls of the female gametophyte move towards the nucellus as components of the third major secretion.

Effect of Facial Cooling on Mucosal Blood Flow in the Mouth in Humans

1. To determine the effects of facial cooling on intraoral thermal events, we placed a thermal conductivity sensor on the buccal surface of the left cheek in six normal and six asthmatic subjects. Room temperature and cold stimuli were then applied to the integument surface of both sides of the face while mucosal surface temperature and thermal conductivity, as an index of blood flow, were recorded. 2. The room temperature challenge had no effect. Application of the cold stimulus to the exterior of the left cheek caused a monotonic decrease in temperature in the mouth in all subjects and was associated with a change in thermal conductivity in which blood flow increased and then fell to baseline despite a continued drop in temperature. These responses were purely local in that cooling of the right side of the face did not change the temperature or blood flow on the left side. No differences were noted between the asthmatic and normal subjects. 3. The data indicate that lowering the temperature of the skin of the face produces significant alterations in the thermal environment within the mouth. With facial cooling, buccal temperature falls and mucosal blood supply transiently rises. This effect appears to be a purely local thermally mediated event. Facial pressure and cutaneous reflexes do not play a role. The above changes may contribute to the conditioning of inspired air during oral breathing.

Molecular mechanism of mucin secretion: I. The role of intragranular charge shielding.

Mucus is an ubiquitous polymer hydrogel that functions as a protective coat on the surface of integument and mucosa of species ranging from simple animals (such as coelenterates) to mammals. The polymer matrix of mucus is made out of long-chain glycoproteins called mucins that are tangled together, forming a randomly woven, highly polyionic network (Lee et al., 1977; Verdugo et al., 1983). Mucin-containing granules, produced by mammalian goblet cells in vitro, undergo massive post-exocytotic swelling. Their swelling kinetics is similar to the swelling of condensed artificial polymer gels (Verdugo, 1984; Tanaka and Fillmore, 1979). We had proposed that mucins must be condensed in the secretory granule and expand by hydration during or after exocytosis (Verdugo, 1984; Tam and Verdugo, 1981). However, the polyionic charges of mucins prevents condensation unless they (the mucins) are appropriately shielded. The present experiments were designed to assert the presence of an intragranular shielding cation and its role in secretion. Giant mucin granules of the slug (Ariolimax columbianus) are released intact from mucus-secreting cells of the slug's skin. They burst spontaneously outside the cell, forming, upon hydration, the typical slug mucus (Deyrup-Olsen et al., 1983). We report here that these granules contain from 2.5 to 3.6 moles calcium/kg dry material, and that calcium is released from the granules immediately before the burst that discharges their secretory product. Therefore, we propose that calcium functions as a shielding cation of polyionic mucins, and that the bursting discharge of mucins from secretory granules must result from the release of calcium from the intragranular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

The T-Shirt Test: Identifying Oneself through Smell

Olfaction has always been a sense that stimulates an interest in teenagers. As students reach adolescence, their awareness of odor in and around the immediate environment rises. Because of the enormous physiologic and psychologic changes they are experiencing through puberty, students become keenly aware that their peers are generating odor. Researchers acknowledge that it is during these adolescent years that the apocrine and sebaceous glands in the dermis of the skin become the most active. This causes a tremendously varied array of liquified aromas to build on the integument's surface. It is during this time that a person's olfactory awareness enters a new dimension. Amazingly, the scent molecules generated by a person are unique to that person. No one else chemically replicates in his body the exact odors of another. In essence, each human generates a personal label. Animals with a keen olfactory sense can easily identify separate individuals. This is why, for example, a bloodhound can follow the scent of an escaped convict through an environment rich in its own odors. While the sense of smell in humans is not as acute as the hounds', it is sensitive enough for people to recognize their own label. The following exercise is fun to perform, and demonstrates beautifully the keenness of human olfaction. Before this lab can be conducted, the instructor must obtain at least ten t-shirts. The sizes may vary, but effort must be made to assure that color, design and composition of the t-shirts are identical. To make sure that none of the shirts contains a unique odor, wash all the t-shirts in the same soap or detergent and dry them in an identical fashion several days before the laboratory exercise is to take place. A day or two before the lab, select students who are willing to wear the t-shirt next to their skin for a minimum of 24 continuous hours. This group must also promise not to bathe, shower nor use any scent-producing products (i.e, soaps, perfumes, deodorants) for the duration of the experiment. The best results are obtained if the participants can be talked into wearing the shirt continuously for 36 hours, but a 24-hour time period can produce significant outcomes. Just prior to attending the lab, tell the participants to stop by the locker room or bathroom to remove their t-shirts. Upon entering the lab, they should present the shirt to the instructor who should immediately label the shirt with a sticker with the participant's name on it to assure proper identification during collection. Have the whole class perform a short olfactory related exercise* to allow the instructor time to separate the retrieved t-shirts into separate clean shopping bags. These bags should have no individual markings, but should be identified by a number or letter written on the bag's bottom. The instructor must write the number or letter of the bag into which a student's t-shirt is placed on the identification sticker of the shirt. This sticker is then removed and placed on a clipboard with the other participants' stickers, also so marked. An alternative procedure is to place the participant's sticker onto the bottom of the bag into which his shirt was placed, but if this alternative is selected, additional care must be taken during the lab to assure that students do not see the stickers. Place the labeled bags in random fashion together on a demonstration counter in the room, and summon participants to the counter separately. Ask them to identify, using only the sense of smell, the t-shirts they had worn the previous 24 hours. It is important for the instructor to tell the subjects it is okay to lift the shirt from the bag in a ball, but not to straighten it out and hold it up. This will elimi-