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At least 109 records · Page 6Linked to original sources
PubMed2004

Cytological and biochemical evidence for a gonad-preferential interplay of SmFKBP12 and SmTbetaR-I in Schistosoma mansoni.

In eukaryotes, FK506-binding proteins with a molecular weight of 12 kDa (FKBP12s) influence a variety of signal transduction pathways that regulate cell division, differentiation, and ion homeostasis. Amongst these, TGFbeta signaling and calcineurin (CN) phosphatase activity is modulated by FKBP12 via binding to TGFbeta-family type I receptors (TbetaR-Is) or to the CN subunit A, respectively. In this work, we demonstrate the tissue-specific expression of the Schistosoma mansoni FKBP12 homologue (SmFKBP12) in the gonads of female parasites as well as in the tegument of both genders. Components of the TGFbeta pathway have been characterized in schistosomes and their roles in mediating host-parasite or male-female interactions proposed. We show that a schistosome TGFbeta-family type I receptor (SmTbetaR-I, SmRK-1) is expressed in the female gonads, suggesting that SmFKBP12 may regulate its activity in this tissue. This hypothesis is supported by yeast two-hybrid analyses showing a direct binding of SmFKBP12 and SmTbetaR-I, which was specifically inhibited by the drug FK506. Our data provide the first evidence for the activity of a transmembrane receptor in the vitellarium of schistosome females and indicate that FKBP12-meditated regulation of the TGFbeta pathway is evolutionarily conserved in a primitive metazoan such as Schistosoma. Furthermore, we show that the schistosome CN (SmCN) is not expressed in the female gonads, but co-localizes with SmFKBP12 only in the tegument. From these data we conclude an SmFKBP12/SmTbetaR-I, but not an SmCN/SmFKBP12 interplay in the female gonads.

Animals↗
PubMed2006

Biodegradability of leathers through anaerobic pathway.

Leather processing generates huge amounts of both solid and liquid wastes. The management of solid wastes, especially tanned leather waste, is a challenging problem faced by tanners. Hence, studies on biodegradability of leather become imperative. In this present work, biodegradability of untanned, chrome tanned and vegetable tanned leather under anaerobic conditions has been addressed. Two different sources of anaerobes have been used for this purpose. The effect of detanning as a pretreatment method before subjecting the leather to biodegradation has also been studied. It has been found that vegetable tanned leather leads to more gas production than chrome tanned leather. Mixed anaerobic isolates when employed as an inoculum are able to degrade the soluble organics of vegetable tanned material and thus exhibit an increased level of gas production during the initial days, compared to the results of the treatments that received the anaerobic sludge. With chrome tanned materials, there was not much change in the volume of the gas produced from the two different sources. It has been found that detanning tends to improve the biodegradability of both types of leathers.

Anaerobiosis↗
PubMed2004

Morpho-regulation of ectodermal organs: integument pathology and phenotypic variations in K14-Noggin engineered mice through modulation of bone morphogenic protein pathway.

Ectodermal organs are composed of keratinocytes organized in different ways during induction, morphogenesis, differentiation, and regenerative stages. We hypothesize that an imbalance of fundamental signaling pathways should affect multiple ectodermal organs in a spatio-temporal-dependent manner. We produced a K14-Noggin transgenic mouse to modulate bone morphogenic protein (BMP) activity and test the extent of this hypothesis. We observed thickened skin epidermis, increased hair density, altered hair types, faster anagen re-entry, and formation of compound vibrissa follicles. The eyelid opening was smaller and ectopic cilia formed at the expense of Meibomian glands. In the distal limb, there were agenesis and hyperpigmentation of claws, interdigital webbing, reduced footpads, and trans-differentiation of sweat glands into hairs. The size of external genitalia increased in both sexes, but they remained fertile. We conclude that modulation of BMP activity can affect the number of ectodermal organs by acting during induction stages, influence the size and shape by acting during morphogenesis stages, change phenotypes by acting during differentiation stages, and facilitate new growth by acting during regeneration stages. Therefore during organogenesis, BMP antagonists can produce a spectrum of phenotypes in a stage-dependent manner by adjusting the level of BMP activity. The distinction between phenotypic variations and pathological changes is discussed.

Animals↗
PubMed2003

An ultrastructural study of connective tissue in mollusc integument III. Cephalopoda.

We studied structure and ultrastructure of the subepidermal connective tissue (SEC) of the integument of three cephalopods (Sepia officinalis, Octopus vulgaris and Loligo pealii). In all species, three distinct regions of the SEC were recognised: (a) an outer zone (OZ) that included the dermal-epidermal junction, and consisted of a thin layer of connective tissue containing muscles, (b) an extensive middle zone (MZ) containing a compact network of collagen fibres and numerous cells, (c) an inner zone (IZ) of loose connective tissue that merged with muscular fascia. This arrangement differs from that in bivalves and gastropods and recalls vertebrate integument. The dermal-epidermal junction of cephalopods differed from that of bivalves, gastropods and mammals in that the epidermal cells did not possess hemidesmosomes, and their intermediate filaments terminated directly in the plasmamembrane. The thick (120-500 nm) basal membrane (BM) had a superficial zone containing a regular array of granules; a lamina densa composed of a compact network of small filaments and granules; and an IZ distinguished by expansions of granular material protruding into underlying structures. Collagen fibres contained fibroblast-derived cytoplasmic thread, running through their centres and were surrounded by granular material that joins them to adjacent fibres. The collagen fibrils were of medium diameter (30-80 nm) had the typical ultrastructure of fibrillar collagens, and were surrounded by abundant interfibrillar material. The hypodermis was loose, with a network of small bundles of collagen fibrils. Cephalopod integument appears to represent a major evolutionary step distinguishing this class of molluscs.

Animals↗
PubMed2003

Characterization of the cuticular surface wax pores and the waxy particles of the dustywing, Semidalis flinti (Neuroptera: Coniopterygidae).

The adult dustywing, Semidalis flinti Meinander (Neuroptera: Coniopterygidae), begins producing circular-shaped waxy particles after eclosion. The waxy material, which forms the particles, is extruded from individual pores found in clusters on the abdomen. Pores also are present in two rows of three pores on the frontalis and two pores on the first segment of each antennae. The pores have a rosette-like appearance and each pore extrudes dual waxy ribbons. As each ribbon extends a short distance out of the pore, it begins to curl back on itself until the end makes contact with the ribbon. The curled end then breaks free from the extruding ribbon to form the circular waxy particles with fluted edges approximately 2.75-microm diameter. The adults use the particles to cover all parts of their body except for their eyes and appear to lightly coat their antennae. The lipid portion of the particles consists largely of free fatty acids, almost exclusively the 24-carbon fatty acid, tetracosanoic acid. Minor lipid classes are hydrocarbons, fatty alcohols and unidentified material.

Aging↗
PubMed2004

Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids.

Tyrannosauroids are one of the last and the most successful large-bodied predatory dinosaur groups, but their early history remains poorly understood. Here we report a new basal tyrannosauroid from the Early Cretaceous Yixian Formation of western Liaoning, China, which is small and gracile and has relatively long arms with three-fingered hands. The new taxon is the earliest known unquestionable tyrannosauroid found so far. It shows a mosaic of characters, including a derived cranial structure resembling that of derived tyrannosauroids and a primitive postcranial skeleton similar to basal coelurosaurians. One of the specimens also preserves a filamentous integumentary covering similar to that of other coelurosaurian theropods from western Liaoning. This provides the first direct fossil evidence that tyrannosauroids had protofeathers.

Animals↗
PubMed2006

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago.

Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought.

Animals↗
PubMed2003

Chemical defence in a sawfly: genetic components of variation in relevant life-history traits.

Larvae of several tenthredinid sawfly species readily release droplets of haemolymph through their integument when attacked by predators. This defence mechanism via 'bleeding' is characterised by a low integument resistance and a high haemolymph deterrence. Both traits are variable, and negatively correlated among species. We sought to determine if such differences in the propensity to bleed also occur intraspecifically by studying the heritability of traits potentially associated with the bleeding phenomenon in the turnip sawfly Athalia rosae ruficornis Jakovlev (Hymenoptera: Tenthredinidae, Allantinae). For three European populations, heritabilities were estimated in the laboratory in a parent-offspring and a full-sib design for haemolymph deterrence (measured as concentration of sequestered glucosinolate), integument resistance, body mass of eonymph and adult, and developmental time. Within A. rosae, no significant negative phenotypic correlation was found between the two traits directly related to the defence mechanism: integument resistance and haemolymph deterrence. However, the significant heritabilities found for these traits in the full-sib analysis (0.39 and 0.35, respectively, for males in the Swiss population) show that the variation has a genetic component. While full-sib analysis revealed highly significant heritabilities for most traits in all the three populations, parent-offspring regression revealed little or no evidence of heritable variation. Effects of common environment for siblings and variation in the host-plant quality between insect generations are likely to be the main factors explaining these differences. A consequence of such host-plant variation in the wild might be that genetic variation of such chemical defensive traits is largely invisible to natural selection.

Alleles↗
PubMed2003

Covering the limb--formation of the integument.

An organism's outermost covering, the integument, has evolved to fulfil a diverse range of functions. Skin provides a physical barrier, an environment for immunological surveillance, and also performs a range of sensory, thermoregulatory and biosynthetic functions. Examination of the skin of limb digits reveals a range of skin types including the thickened hairless epidermis of the toe pads (palmar or plantar epidermis) and thinner epidermis between the hair follicles (interfollicular epidermis) of hairy skin. An important developmental function of skin is to give rise to a diverse group of appendages including hair follicles, with associated sebaceous glands (or feathers and scales in chick), eccrine sweat glands and the nail. A key question is how does this morphological variety arise from the single-layered epithelium covering embryonic limb buds? This review will attempt to address this question by linking the extensive morphological/anatomical data on maturation of epidermis and its appendages with (1) current research into the range, plasticity and location of the putative epidermal stems cells; (2) molecular/microenvironmental regulation of epidermal stem cell lineages and lineage choice; and (3) regulation of the differentiation pathways, focusing on differentiation of the interfollicular epidermis.

Animals↗
PubMed2006

Application of nano-indenter for investigation of the properties of the elytra cuticle of the dung beetle (Copris ochus Motschulsky).

The nanomechanical properties of the multilayer elytra cuticle of the dung beetle (Copris ochus Motschulsky) were investigated in the vertical and transverse directions using a nano-indenter. The reduced modulus Ev and hardness Hv of the surface cuticle in the vertical direction obtained by nano-indentation were 3.54+/-0.12 GPa and 0.20+/-0.01 GP, respectively. The nano-indentation result showed that the reduced modulus E(t) and hardness Ht of each layer were gradually reduced from the outer layer to the inner layer in the transverse direction. Ev was less than the largest Et presented at the outer layer (7.06+/-0.54 GPa). It was supposedly formed as a result of the composite effect of the multilayer. Without consideration of the anisotropy of chitin, an experimental model was proposed to describe the nanomechanical properties of the elytra cuticle.

Animals↗
PubMedDate not supplied

Gd3+-sensitive Na+ transport across the integument of Hirudo medicinalis.

Leeches Hirudo medicinalis were exposed to either artificial pond water (APW; 1 mM NaCl) or to high-salinity conditions (HS; 200 mM NaCl) for several days. The aim of the study was to assess whether transepithelial ion conductances in their dorsal integuments were affected by this long-term acclimation. In voltage-clamp experiments using Ussing-type chambers, the transepithelial potential V(T) was clamped to 0 mV, and amiloride-sensitive currents (I(ami)) and total Na(+) transport (I(Na)) were determined. Apical Ca(2+)-free conditions strongly increased I(ami) to a similar magnitude in both differently acclimated integuments. Apical application of the lanthanide gadolinium <0.1 mM decreased the short-circuit current (I(sc)). In contrast, higher concentrations up to 10 mM Gd(3+) upregulated I(sc) by an additional 90% in APW integuments and by an additional 300% in HS integuments. This Gd(3+) effect was due to a doubling of I(Na) in APW and a more than sixfold increase of I(Na) in HS integuments. In summary, the macroscopic electrophysiological variables, including I(Na), were generally not affected by long-term exposure to high salinity. However, the presence of Gd(3+)-sensitive Na(+) conductances or regulating structures were greatly upregulated during HS acclimation.

Acclimatization↗
PubMed2004

Morphology of the integumentary structures in the nymph of lace bug, Stephanitis typica (Hemiptera: Tingidae).

The nymphs of the lace bug Stephanitis typica possess unsegmented, slender, integumentary processes. They are arranged chiefly in three rows on the mid-dorsal and lateral sides. The surface ultrastructure of the integumentary process reveals three types of sensilla, namely, companiform sensilla at the tip of the integumentary process having a probable proprioceptive function, oar-shaped wind and gravity sensilla, and pegs supposed to be hygroscopic.

Animals↗
PubMed2003

Activity levels of 137Cs and 40K in the skin and the cutaneous organs of a cow.

We have performed an extensive study to determine the activity distributions of radiocesium (137Cs) and of the radioisotope 40K of potassium in the whole body of a cow. ICRP assumes that cesium and potassium are distributed homogeneously throughout the whole body of an organism. The current investigation measured concentrations of 137Cs and 40K in components of the skin, horns, and hooves of a cow. Activity levels of 137Cs were caused by the long-term ingestion following the Chernobyl fallout, whereas the naturally occurring potassium (40K) is an essential part of cow's normal diet. The cow was born at the time of the fallout following the Chernobyl accident and had ingested heavily contaminated forage during its entire lifetime. Activities of 137Cs and 40K were determined simultaneously by gamma spectrometry. All activities are related to the day of slaughter and include also corrections for self attenuation of photons caused by the different densities of the samples. Radionuclide concentrations in samples were corrected for moisture losses incurred during freezing and sample preparation. Surface contamination on the skin was estimated by rinsing it in heated water followed by removal of the epidermis and hair. In comparison with the activities of the components of the skin we observed a considerable amount of external contamination on the surface of the skin. But with respect to whole body countings of the animal this amount of external contamination appears to be negligible. It was found that activity ratios of 137Cs to 40K are greater than 1 in all measured components. The average activity concentrations of 137Cs and 40K in the common integument are 23.3 Bq kg(-1) and 13.3 Bq kg(-1), respectively. The highest activity concentrations of 137Cs and 40K were measured in clean hair and hypodermis. Despite being its largest organ, the cow's skin contains probably less than 1% of the animal's whole body 137Cs activity.

Administration, Oral↗
PubMed2004

A novel mouse type I intermediate filament gene, keratin 17n (K17n), exhibits preferred expression in nail tissue.

Inactivating the type I keratin 17 gene (mK17) causes severe but reversible hair loss in a strain-dependent fashion in mouse (McGowan et al, Genes Dev. 16:1412, 2002). Missense mutations in human K17 give rise to two dominantly inherited disorders apparented to ectodermal dysplasias, pachyonychia congenita (PC), and steatocystoma multiplex (SM). In contrast to the null phenotype in mouse, marked lesions are seen in the nail and nail bed and sebaceous glands of PC and SM patients, respectively. In an effort to understand the lack of nail involvement in mK17 null mice, we discovered that the gene located immediately 5' upstream from mK17 is functional and encodes a type I keratin protein highly analogous to mK17. mRNA and protein localization studies show that the expression of this novel gene is highly restricted and most prevalent in the nail bed and matrix, leading to its designation as mK17n (n stands for nail). Weak expression of mK17n also occurs in vibrissae follicles, in filiform and fungiform papillae of oral mucosa. These findings have direct implications for the mK17 null phenotype. Depending on the existence of a human ortholog or a functional equivalent, our findings may also provide a molecular explanation for several unusual aspects of hK17-based diseases.

Amino Acid Sequence↗
PubMed2006

Pigment pattern formation in the quail mutant of the silkworm, Bombyx mori: parallel increase of pteridine biosynthesis and pigmentation of melanin and ommochromes.

The larval pigment pattern in the silkworm, Bombyx mori, is formed by melanin, ommochromes and pteridines. During development all these pigments are synthesized autonomously, and possibly also with mutual interaction between them, to yield unique pigment patterns. In order to find the key trigger for such pigment pattern formation, developmental changes in pteridine biosynthesis were studied using the quail mutant (q/q), which has darker larval marks formed by melanin and an abundance of ommochromes in the integument. In the current study, emphasis has been placed on the analysis of GTP-cyclohydrolase I (GTP-CH I), which is a key enzyme for the biosynthesis of pteridines, during the development of the silkworm. Results of Northern blotting showed that in the quail mutant strong signals of GTP-CH I mRNA appeared around each period of ecdysis, while no such signals appeared in the background strain (+q/q) used. Also, both GTP-CH I activities and pteridine content were higher in the quail mutant compared with the background strain. These results strongly suggest that pteridine biosynthesis is closely linked to the formation of melanin and ommochromes. It is also suggested here that in the silkworm a recessive gene (q) may be involved in the regulation of its pigment pattern formation.

Alcohol Oxidoreductases↗