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Sample records for exuvium

  1. Material properties of the skin of the Kenyan sand boa Gongylophis colubrinus (Squamata, Boidae).

    PubMed

    Klein, Marie-Christin G; Deuschle, Julia K; Gorb, Stanislav N

    2010-09-01

    On the basis of structural data, it has been previously assumed that the integument of snakes consists of a hard, robust, inflexible outer surface (Oberhäutchen and beta-layer) and soft, flexible inner layers (alpha-layers). The aim of this study was to compare material properties of the outer and inner scale layers of the exuvium of Gongylophis colubrinus, to relate the structure of the snake integument to its mechanical properties. The nanoindentation experiments have demonstrated that the outer scale layers are harder, and have a higher effective elastic modulus than the inner scale layers. The results obtained provide strong evidence about the presence of a gradient in the material properties of the snake integument. The possible functional significance of this gradient is discussed here as a feature minimizing damage to the integument during sliding locomotion on an abrasive surface, such as sand.

  2. Body louse remains found in textiles excavated at Masada, Israel.

    PubMed

    Mumcuoglu, K Y; Zias, J; Tarshis, M; Lavi, M; Stiebel, G D

    2003-07-01

    A leg of the body louse, Pediculus humanus humanus L. (Phthiraptera: Pediculidae), was found in a storeroom at Masada build during the reign of King Herod the Great. The unearthed culture material clearly indicates that the room was occupied by the rebels during the first Jewish revolt against the Romans (AD 66-73/4). The context of the textiles associated with the louse and their nature suggest a rebel origin. An exuvium of a leg of the third nymphal stage of body louse was found. The first three parts of the leg (tarsus, including the tarsal claw, tibia and femur) were preserved entirely, while the fourth segment of the leg, the trochanter, was only partially conserved. The comparison of the tarsus of this specimen with the legs of present day third instar nymphs of body and head lice revealed that the leg found within the archaeological debris belongs to a body louse.

  3. Developmental strategy of the endoparasite Xenos vesparum (strepsiptera, Insecta): host invasion and elusion of its defense reactions.

    PubMed

    Manfredini, Fabio; Giusti, Fabiola; Beani, Laura; Dallai, Romano

    2007-07-01

    To successfully complete its endoparasitic development, the strepsipteran Xenos vesparum needs to elude the defense mechanisms of its host, the wasp Polistes dominulus. SEM and TEM observations after artificial infections allow us to outline the steps of this intimate host-parasite association. Triungulins, the mobile 1st instar larvae of this parasite, are able to "softly" overcome structural barriers of the larval wasp (cuticle and epidermis) without any traumatic reaction at the entry site, to reach the hemocoel where they settle. The parasite molts 48 h later to a 2nd instar larva, which moves away from the 1st instar exuvium, molts twice more without ecdysis (a feature unique to Strepsiptera) and pupates, if male, or develops into a neotenic female. Host encapsulation involves the abandoned 1st larval exuvium, but not the living parasite. In contrast to the usual process of encapsulation, it occurs only 48 h after host invasion or later, and without any melanization. In further experiments, first, we verified Xenos vesparum's ability to reinfect an already parasitized wasp larva. Second, 2nd instar larvae implanted in a new host did not evoke any response by hemocytes. Third, we tested the efficiency of host defense mechanisms by implanting nylon filaments in control larval wasps, excluding any effect due the dynamic behavior of a living parasite; within a few minutes, we observed the beginning of a typical melanotic encapsulation plus an initial melanization in the wound site. We conclude that the immune response of the wasp is manipulated by the parasite, which is able to delay and redirect encapsulation towards a pseudo-target, the exuvia of triungulins, and to elude hemocyte attack through an active suppression of the immune defense and/or a passive avoidance of encapsulation by peculiar surface chemical properties. PMID:17437299

  4. A new genus of Nanaloricidae (Loricifera) from deep-sea sediments of volcanic origin in the Kilinailau Trench north of Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Gad, Gunnar

    2004-02-01

    A new genus and species of Nanaloricidae (Loricifera), Phoeniciloricus simplidigitatus, is described inhabiting fine sand covered by a layer of volcanic ash at a water depth of 1,813 m in the New Ireland Basin near the Kilinailau Trench (north of Papua New Guinea). The described specimen is a postlarva enclosed in a larval exuvium. This is the first report of a species belonging to the Nanaloricidae from the deep sea. This occurrence is surprising, because Nanaloricidae are typical inhabitants of coarse sands in the intertidal or littoral zone. Preference for these shallow water habitats is reflected in many morphological features which characterize the Nanaloricidae, and are not normally found in Loricifera inhabiting fine-grained, clayish, deep-sea bottoms. The postlarva of the new species is characterized by a long narrow mouth tube, an urn-shaped lorica divided into ten plates, and 13 small lorica spikes. Distinguishing features of the Higgins-larva include short spinose toes lacking mucros but having small and slightly enlarged bases, short scalids on the introvert, many thoracic plates arranged in 6-8 rows, numerous small papillate flosculi in the collar and caudal regions, and three pairs of filiform, short locomotory appendages on the ventral side. Some features of the new species, especially of the Higgins-larva, are discussed as adaptations to the deep-sea environment.

  5. The taxonomic value of the structures for the insertion of the stylet muscles in the Eutardigrada, and description of a new genus.

    PubMed

    Pilato, Giovanni

    2013-01-01

    The new genus Dastychius has been instituted for the species Isohypsibius improvisus Dastych, 1984. It has claws of the Isohypsibius type, rigid buccal tube without ventral lamina and with ridge-shaped apophyses for the insertion of the stylet muscles; peribuccal lamellae absent; peribuccal papulae seem to be present but the datum should be confirmed; pharyngeal bulb with apophyses and placoids, lunules present in the known species; smooth eggs laid in the exuvium. The apophyses for the insertion of the stylet muscles have some peculiarities that justify the institution of a new genus. They are long, uninterrupted ridges tailing off caudally almost reaching the stylet supports; at almost a quarter of their length they have an incision and a septum never noted in other genera of Eutardigrada. In the author's opinion it is possible to hypothesize that all the structures for the insertion of the stylet muscles recognizable in the Eutardigrada may be derived from long ridge-shaped apophyses (but without incision and septum). The comparison of the shape of the apophyses for the insertion of the stylet muscles in the Eutardigrada seems to indicate that this character has taxonomic value at level of genus but not at family level.

  6. Epidermis architecture and material properties of the skin of four snake species.

    PubMed

    Klein, Marie-Christin G; Gorb, Stanislav N

    2012-11-01

    On the basis of structural and experimental data, it was previously demonstrated that the snake integument consists of a hard, robust, inflexible outer surface (Oberhäutchen and β-layer) and softer, flexible inner layers (α-layers). It is not clear whether this phenomenon is a general adaptation of snakes to limbless locomotion or only to specific conditions, such as habitat and locomotion. The aim of the present study was to compare the structure and material properties of the outer scale layers (OSLs) and inner scale layers (ISLs) of the exuvium epidermis in four snake species specialized to live in different habitats: Lampropeltis getula californiae (terrestrial), Epicrates cenchria cenchria (generalist), Morelia viridis (arboreal) and Gongylophis colubrinus (sand-burrowing). Scanning electron microscopy (SEM) of skin cross sections revealed a strong variation in the epidermis structure between species. The nanoindentation experiments clearly demonstrated a gradient of material properties along the epidermis in the integument of all the species studied. The presence of such a gradient is a possible adaptation to locomotion and wear minimization on natural substrates. In general, the difference in both the effective elastic modulus and hardness of the OSL and ISL between species was not large compared with the difference in epidermis thickness and architecture.

  7. Cuticular protein with a low complexity sequence becomes cross-linked during insect cuticle sclerotization and is required for the adult molt

    PubMed Central

    Mun, Seulgi; Young Noh, Mi; Dittmer, Neal T.; Muthukrishnan, Subbaratnam; Kramer, Karl J.; Kanost, Michael R.; Arakane, Yasuyuki

    2015-01-01

    In the insect cuticle, structural proteins (CPs) and the polysaccharide chitin are the major components. It has been hypothesized that CPs are cross-linked to other CPs and possibly to chitin by quinones or quinone methides produced by the laccase2-mediated oxidation of N-acylcatechols. In this study we investigated functions of TcCP30, the third most abundant CP in protein extracts of elytra (wing covers) from Tribolium castaneum adults. The mature TcCP30 protein has a low complexity and highly polar amino acid sequence. TcCP30 is localized with chitin in horizontal laminae and vertically oriented columnar structures in rigid cuticles, but not in soft and membranous cuticles. Immunoblot analysis revealed that TcCP30 undergoes laccase2-mediated cross-linking during cuticle maturation in vivo, a process confirmed in vitro using recombinant rTcCP30. We identified TcCPR27 and TcCPR18, the two most abundant proteins in the elytra, as putative cross-linking partners of TcCP30. RNAi for the TcCP30 gene had no effect on larval and pupal growth and development. However, during adult eclosion, ~70% of the adults were unable to shed their exuvium and died. These results support the hypothesis that TcCP30 plays an integral role as a cross-linked structural protein in the formation of lightweight rigid cuticle of the beetle. PMID:25994234

  8. Postecdysis Sclerotization of Mouthparts of the Formosan Subterranean Termites (Isoptera: Rhinotermitidae).

    PubMed

    Kakkar, Garima; Chouvenc, Thomas; Su, Nan-Yao

    2016-04-01

    In termites, it is challenging to recognize the incidence of molting in workers because of their successive stationary molt, asynchronous molting among individuals, cryptic behavior, a soft and poorly sclerotized cuticle, and they immediately consume the shed exuvia of nestmates. This study describes a method in which the degree of sclerotization of the mouthparts in newly molted workers of the Formosan subterranean termite can be quantified and used to determine if an individual has recently molted, within a 36-h time frame. Changes in the tanning of mouthparts over time were used as a measure of the index of sclerotization in workers postmolting. Upon ecdysis, the primary point of articulation of the mandible already initiated sclerotization, which may allow the movement of the mandibles during the shedding of the exuvium. The sclerotization of the secondary point of articulation and the mandibular teeth, and the width of sclerotization of the mandibles, progressively increased until reaching a plateau around 36-h postecdysis, which imply that workers can regain some level of activity as early as 2 d after ecdysis. Our observations allowed for the determination of variables for the sclerotization of the mouthparts to easily identify workers that recently molted, and this method will be useful in future studies that focus on the molting activity of workers over time and space within a termite colony, in the scope of improving current control strategies for termite pests.

  9. New tardigrade records for the Baltic states with a description of Minibiotus formosus sp. n. (Eutardigrada, Macrobiotidae)

    PubMed Central

    Zawierucha, Krzysztof; Dziamięcki, Jakub; Jakubowska, Natalia; Michalczyk, Łukasz; Kaczmarek, Łukasz

    2014-01-01

    Abstract In sixteen moss, lichen and mixed (moss/lichen) samples, collected from Estonia, Latvia and Lithuania, 291 specimens, 48 simplexes, including one exuvium with 6 eggs, and 8 free-laid eggs of eutardigrades were found. In total, 17 species, together with one new to science, were identified (all are new records for the Baltic states): Astatumen bartosi, Diphascon (Adropion) prorsirostre, D. (Diphascon) bullatum, D. (D.) pingue pingue, D. (D.) recamieri, D. (D.) rugosum, Hypsibius convergens, H. dujardini, H. cf. scabropygus, Isohypsibius ronsisvallei, I. sattleri, Macrobiotus harmsworthi harmsworthi, M. hufelandi hufelandi, Milnesium asiaticum, Milnesium tardigradum tardigradum, Minibiotus formosus sp. n. and Paramacrobiotus richtersi. The new species is most similar to Minibiotus gumersindoi, but differs from it mainly by the presence of two types of cuticular pores, the absence of a triangular or pentagonal arrangement of pores above a single large pore on legs, the presence of granulation on all legs and a different macroplacoid length sequence. In this paper we also provide photographs and morphometrics of H. cf. scabropygus. PMID:24899839

  10. Postecdysis Sclerotization of Mouthparts of the Formosan Subterranean Termites (Isoptera: Rhinotermitidae).

    PubMed

    Kakkar, Garima; Chouvenc, Thomas; Su, Nan-Yao

    2016-04-01

    In termites, it is challenging to recognize the incidence of molting in workers because of their successive stationary molt, asynchronous molting among individuals, cryptic behavior, a soft and poorly sclerotized cuticle, and they immediately consume the shed exuvia of nestmates. This study describes a method in which the degree of sclerotization of the mouthparts in newly molted workers of the Formosan subterranean termite can be quantified and used to determine if an individual has recently molted, within a 36-h time frame. Changes in the tanning of mouthparts over time were used as a measure of the index of sclerotization in workers postmolting. Upon ecdysis, the primary point of articulation of the mandible already initiated sclerotization, which may allow the movement of the mandibles during the shedding of the exuvium. The sclerotization of the secondary point of articulation and the mandibular teeth, and the width of sclerotization of the mandibles, progressively increased until reaching a plateau around 36-h postecdysis, which imply that workers can regain some level of activity as early as 2 d after ecdysis. Our observations allowed for the determination of variables for the sclerotization of the mouthparts to easily identify workers that recently molted, and this method will be useful in future studies that focus on the molting activity of workers over time and space within a termite colony, in the scope of improving current control strategies for termite pests. PMID:26743216

  11. Conjugation in Hyalophysa chattoni Bradbury (Apostomatida): An adaptation to a symbiotic life cycle.

    PubMed

    Bradbury, Phyllis Clarke; Hash, Stephen M; Rogers, Faye Kucera; Neptun, Steven H; Zhang, Limin

    2013-11-01

    Hyalophysa chattoni, borne as an encysted phoront on a crustacean's exoskeleton, metamorphoses to the trophont during the host's premolt. After the molt within 15min to 2h conjugants with food vacuoles appear in the exuvium, swimming along with the trophonts. Starvation in other ciliates usually precedes conjugation, but food vacuoles in conjugants do not preclude starvation. Only after ingestion and dehydration of vacuoles ceases, does digestion of exuvial fluid begin. Conjugants resorb their feeding apparatus as they fuse. A single imperforate membrane from each partner forms the junction membrane. In a reproductive cyst conjugants divide synchronously, but now the junction membrane is interrupted by pores and channels. After the last division the daughters undergo meiosis--two meiotic divisions and one mitotic division yielding two prokarya as they simultaneously differentiate into tomites. After fertilization, pairs separate and the synkaryon divides once into a macronuclear anlage and a micronucleus. Exconjugants leave the cyst and seek a host. The parental macronucleus remains active until the phoront stage when the anlage develops. Owing to random association of micronuclei during meiosis, Hyalophysa's exconjugants are more genetically diverse than exconjugants from conventional patterns of conjugation. PMID:23706651

  12. New tardigrade records for the Baltic states with a description of Minibiotus formosus sp. n. (Eutardigrada, Macrobiotidae).

    PubMed

    Zawierucha, Krzysztof; Dziamięcki, Jakub; Jakubowska, Natalia; Michalczyk, Lukasz; Kaczmarek, Lukasz

    2014-01-01

    In sixteen moss, lichen and mixed (moss/lichen) samples, collected from Estonia, Latvia and Lithuania, 291 specimens, 48 simplexes, including one exuvium with 6 eggs, and 8 free-laid eggs of eutardigrades were found. In total, 17 species, together with one new to science, were identified (all are new records for the Baltic states): Astatumen bartosi, Diphascon (Adropion) prorsirostre, D. (Diphascon) bullatum, D. (D.) pingue pingue, D. (D.) recamieri, D. (D.) rugosum, Hypsibius convergens, H. dujardini, H. cf. scabropygus, Isohypsibius ronsisvallei, I. sattleri, Macrobiotus harmsworthi harmsworthi, M. hufelandi hufelandi, Milnesium asiaticum, Milnesium tardigradum tardigradum, Minibiotus formosus sp. n. and Paramacrobiotus richtersi. The new species is most similar to Minibiotus gumersindoi, but differs from it mainly by the presence of two types of cuticular pores, the absence of a triangular or pentagonal arrangement of pores above a single large pore on legs, the presence of granulation on all legs and a different macroplacoid length sequence. In this paper we also provide photographs and morphometrics of H. cf. scabropygus.

  13. Epidermis architecture and material properties of the skin of four snake species

    PubMed Central

    Klein, Marie-Christin G.; Gorb, Stanislav N.

    2012-01-01

    On the basis of structural and experimental data, it was previously demonstrated that the snake integument consists of a hard, robust, inflexible outer surface (Oberhäutchen and β-layer) and softer, flexible inner layers (α-layers). It is not clear whether this phenomenon is a general adaptation of snakes to limbless locomotion or only to specific conditions, such as habitat and locomotion. The aim of the present study was to compare the structure and material properties of the outer scale layers (OSLs) and inner scale layers (ISLs) of the exuvium epidermis in four snake species specialized to live in different habitats: Lampropeltis getula californiae (terrestrial), Epicrates cenchria cenchria (generalist), Morelia viridis (arboreal) and Gongylophis colubrinus (sand-burrowing). Scanning electron microscopy (SEM) of skin cross sections revealed a strong variation in the epidermis structure between species. The nanoindentation experiments clearly demonstrated a gradient of material properties along the epidermis in the integument of all the species studied. The presence of such a gradient is a possible adaptation to locomotion and wear minimization on natural substrates. In general, the difference in both the effective elastic modulus and hardness of the OSL and ISL between species was not large compared with the difference in epidermis thickness and architecture. PMID:22896567

  14. The taxonomic value of the structures for the insertion of the stylet muscles in the Eutardigrada, and description of a new genus.

    PubMed

    Pilato, Giovanni

    2013-01-01

    The new genus Dastychius has been instituted for the species Isohypsibius improvisus Dastych, 1984. It has claws of the Isohypsibius type, rigid buccal tube without ventral lamina and with ridge-shaped apophyses for the insertion of the stylet muscles; peribuccal lamellae absent; peribuccal papulae seem to be present but the datum should be confirmed; pharyngeal bulb with apophyses and placoids, lunules present in the known species; smooth eggs laid in the exuvium. The apophyses for the insertion of the stylet muscles have some peculiarities that justify the institution of a new genus. They are long, uninterrupted ridges tailing off caudally almost reaching the stylet supports; at almost a quarter of their length they have an incision and a septum never noted in other genera of Eutardigrada. In the author's opinion it is possible to hypothesize that all the structures for the insertion of the stylet muscles recognizable in the Eutardigrada may be derived from long ridge-shaped apophyses (but without incision and septum). The comparison of the shape of the apophyses for the insertion of the stylet muscles in the Eutardigrada seems to indicate that this character has taxonomic value at level of genus but not at family level. PMID:26120681

  15. New tardigrade records for the Baltic states with a description of Minibiotus formosus sp. n. (Eutardigrada, Macrobiotidae).

    PubMed

    Zawierucha, Krzysztof; Dziamięcki, Jakub; Jakubowska, Natalia; Michalczyk, Lukasz; Kaczmarek, Lukasz

    2014-01-01

    In sixteen moss, lichen and mixed (moss/lichen) samples, collected from Estonia, Latvia and Lithuania, 291 specimens, 48 simplexes, including one exuvium with 6 eggs, and 8 free-laid eggs of eutardigrades were found. In total, 17 species, together with one new to science, were identified (all are new records for the Baltic states): Astatumen bartosi, Diphascon (Adropion) prorsirostre, D. (Diphascon) bullatum, D. (D.) pingue pingue, D. (D.) recamieri, D. (D.) rugosum, Hypsibius convergens, H. dujardini, H. cf. scabropygus, Isohypsibius ronsisvallei, I. sattleri, Macrobiotus harmsworthi harmsworthi, M. hufelandi hufelandi, Milnesium asiaticum, Milnesium tardigradum tardigradum, Minibiotus formosus sp. n. and Paramacrobiotus richtersi. The new species is most similar to Minibiotus gumersindoi, but differs from it mainly by the presence of two types of cuticular pores, the absence of a triangular or pentagonal arrangement of pores above a single large pore on legs, the presence of granulation on all legs and a different macroplacoid length sequence. In this paper we also provide photographs and morphometrics of H. cf. scabropygus. PMID:24899839

  16. Loss of function of the yellow-e gene causes dehydration-induced mortality of adult Tribolium castaneum.

    PubMed

    Noh, Mi Young; Kramer, Karl J; Muthukrishnan, Subbaratnam; Beeman, Richard W; Kanost, Michael R; Arakane, Yasuyuki

    2015-03-15

    Yellow protein (dopachrome conversion enzyme, DCE) is involved in the melanin biosynthetic pathway that significantly accelerates pigmentation reactions in insects. Recent studies have suggested that the insect yellow genes represent a rapidly evolving gene family generating functionally diverse paralogs, but the exact physiological functions of several yellow genes are still not understood. To study the function(s) of one of the yellow genes, yellow-e (TcY-e), in the red flour beetle, Tribolium castaneum, we performed real-time PCR to analyze its developmental and tissue-specific expression, and utilized immunohistochemistry to identify the localization of the TcY-e protein in adult cuticle. Injection of double-stranded RNA for TcY-e (dsTcY-e) into late instar larvae had no effect on larval-pupal molting or pupal development. The pupal cuticle, including that lining the setae, gin traps and urogomphi, underwent normal tanning. Adult cuticle tanning including that of the head, mandibles and legs viewed through the translucent pupal cuticle was initiated on schedule (pupal days 4-5), indicating that TcY-e is not required for pupal or pharate adult cuticle pigmentation in T. castaneum. The subsequent pupal-adult molt, however, was adversely affected. Although pupal cuticle apolysis and slippage were evident, some of the adults (~25%) were unable to shed their exuvium and died entrapped in their pupal cuticle. In addition, the resulting adults rapidly became highly desiccated. Interestingly, both the failure of the pupal-adult molt and desiccation-induced mortality were prevented by maintaining the dsTcY-e-treated insects at 100% relative humidity (rh). However, when the high humidity-rescued adults were removed from 100% rh and transferred to 50% rh, they rapidly dehydrated and died, whereas untreated beetles thrived throughout development at 50% rh. We also observed that the body color of the high humidity-rescued dsTcY-e-adults was slightly darker than that of