Tenascin in the human intervertebral disc: alterations with aging and disc degeneration

Our objective for this study was to determine the presence and distribution of tenascin in the human intervertebral disc. The tenascins are a family of extracellular matrix proteins with repeated structural domains homologous to epidermal growth factor, fibronectin type III and the fibrinogens. Little is known about the presence of this protein in the disc. Ten normal human discs donated from subjects newborn to 15 years old, 10 control discs from adult donors aged 24-41 years, and 11 surgical disc specimens from patients aged 26-76 years were examined for immunolocalization of tenascin. In young discs, tenascin was localized throughout the annulus; in the nucleus, localization was confined to pericellular matrix. In adult control and degenerating disc specimens, tenascin in the annulus was localized primarily in pericellular matrix regions encircling either single cells or clusters of disc cells; in rare instances localization was more diffuse in the intraterritorial matrix. In young, healthy disc, tenascin was abundant throughout the annulus. In contrast, degenerating discs in adults showed a localization restricted to the pericellular, and rarely, more restricted intraterritorial matrix. These observations indicate that changes in the amount and distribution of tenascin may have a role in disc aging and degeneration, possibly by modulating fibronectin-disc-cell interactions, and causing alterations in the shape of disc cells.     

Anatomical and chemical characteristics of the seed coat of <i>Medicago sativa</i> L. (alfalfa) cv. Baralfa 85 seeds and their association with seed dormancy

Seeds of alfalfa (Medicago sativa L.) can exhibit seedcoat imposed dormancy, which produces hard seeds within a seed lot. These seeds do not germinate because they do not imbibe water due to a barrier to water entry in the seed coat. The aim of this work was to analyze the anatomical and chemical characteristics of the testa of alfalfa seeds with respect to water permeability levels. The anatomy of seeds of the cv. Baralfa 85 was studied and structural substances, polyphenols, tannins and cutin present in the testa of seeds of different water permeability levels were determined. The anatomical characteristics of the seed coat and the proportions of components were found to determine the permeability level of the seed coat, an aspect that is associated with the physical seed dormancy level. Anatomically, increased thickness of the testa was associated with a lower permeability level. The difference may be attributed to the variation in cuticle thickness, length of macrosclereids and thickness of the cell wall, and presence and development of osteosclereids. From the physiological and chemical points of view, the mechanism of physical dormancy of the testa is explained by a greater amount of components that repel water and cement the cell wall, such as polyphenols, lignins, condensed tannins, pectic substances, and a lower proportion of cellulose and hemicellulose.     

Effects of plant height and row spacing on kenaf forage potential with multiple harvests

Kenaf (Hibiscus cannabinus L.) forage potential can be enhanced through its regrowth capacity and higher production in narrow rows. A field experiment was conducted in Matamoros, Coahuila, Mexico, during 2 growing seasons (2004 and 2005) to study the effects of plant height and row spacing on kenaf forage potential with multiple harvests. This study evaluated the effects of (1) 2 plant heights at cutting (1.0-1.2 m and 1.8-2.0 m) and (2) 4 inter row spacings (0.19, 0.38, 0.57 and 0.76 m) using a 2 x 4 factorial arrangement of treatments in a completely randomized block design with 4 replications. Dry matter (DM) and crude protein (CP) yields, DM partitioning, neutral detergent fiber (NDF) and CP concentrations were determined. Heights at cutting × row spacing interactions were not significant for the monitored variables (p>0.05). Kenaf response to treatments was only relevant for main effects (p≤0.05). Row spacing and plant height affected DM and CP yields (p≤0.05), whereas only plant height affected chemical composition and DM partitioning (p≤0.05). Dry matter (17.0%-26.0%), and CP (12.4%-15.6%) yields were higher (p≤0.05) when plant heights had reached 1.8 to 2.0 m. Row spacing reduction from 0.76 m to 0.38 and 0.19 m increased DM yield (20.4-33.4%) and CP yield (24.2-38.5%) (p≤0.05). Kenaf forage potential increases when planted in narrow rows and harvested 2 or 3 times during the growing season.     

Titin (Visco-) Elasticity in Skeletal Muscle Myofibrils

Titin is the third most abundant protein in sarcomeres and fulfills a number of mechanical and signaling functions. Specifically, titin is responsible for most of the passive forces in sarcomeres and the passive visco-elastic behaviour of myofibrils and muscles. It has been suggested, based on mechanical testing of isolated titin molecules, that titin is an essentially elastic spring if Ig domain un/refolding is prevented either by working at short titin lengths, prior to any unfolding of Ig domains, or at long sarcomere (and titin) lengths when Ig domain un/refolding is effectively prevented. However, these properties of titin, and by extension of muscles, have not been tested with titin in its natural structural environment within a sarcomere. The purpose of this study was to gain insight into the Ig domain un/refolding kinetics and test the idea that titin could behave essentially elastically at any sarcomere length by preventing Ig domain un/refolding during passive stretch-shortening cycles. Although not completely successful, we demonstrate here that titin’s visco-elastic properties appear to depend on the Ig domain un/refolding kinetics and that indeed, titin (and thus myofibrils) can become virtually elastic when Ig domain un/refolding is prevented.     

The chemokine,CXCL16, and its receptor,CXCR6, are constitutively expressed in human annulus fibrosus and expression of CXCL16 is up-regulated by exposure to IL-1ß in vitro

Chemokines are an important group of soluble molecules with specialized functions in inflammation. The roles of many specialized chemokines and their receptors remain poorly understood in the human intervertebral disc. We investigated CXCL16 and its receptor, CXCR6, to determine their immunolocalization in disc tissue and their presence following exposure of cultured human annulus fibrosus cells to proinflammatory cytokines. CXCL16 is a marker for inflammation; it also can induce hypoxia-inducible factor 1α (HIF-1α), which is a phenotypic marker of heathy nucleus pulposus tissue. We found CXCL16 and CXCR6 immunostaining in many cells of the annulus portion of the disc. Molecular studies showed that annulus fibrosus cells exposed to IL-1ß, but not TNF-α, exhibited significant up-regulation of CXCL16 expression vs. control cells. There was no significant difference in the percentage of annulus cells that exhibited immunolocalization of CXCL16 in grade I/II, grade III or grade IV/V specimens. The presence of CXCL16 and its receptor, CXCR6, in the annulus in vivo suggests the need for future research concerning the role of this chemokine in proinflammatory functions, HIF-1α expression and disc vascularization.     

Cephenniini with prothoracic glands and internal cavities: new taxa,enigmatic characters and phylogeny of the Cephennomicrus group of genera (Coleoptera,Staphylinidae, Scydmaeninae)

Genera of the Cephennomicrus group of the Cephenniini (Scydmaenitae) are revised, and the following new taxa are described: Trichokrater gen.n. , Trichokrater ekkentros sp.n. (type species of Trichokrater) (Borneo), Cephennococcus gen.n. , Cephennococcus kuchingensis sp.n. (type species of Cephennococcus) (Borneo), Cephennococcus kenyirensis sp.n. (West Malaysia), Cephennococcus crassus sp.n. (Borneo), Cephennococcus minutissimus sp.n. (West Malaysia), Pomphopsilla gen.n. , Pomphopsilla luhya sp.n. (type species of Pomphopsilla) (Kenya) and Pomphopsilla soror sp.n. (Kenya). Unique subcuticular pockets with setose openings on the pronotum of Trurlia and Trichokrater are identified as glandular structures. Enigmatic internal prothoracic cavities are described for the first time in Scydmaeninae (in Cephennococcus, Pomphopsilla and a female of an undescribed genus from Sulawesi); their fine structure and function remain unknown. Parsimony‐based cladistic analysis of the adult morphology of genera of Cephenniini provided robust evidence for a monophyly of the Cephennomicrus group, composed of Cephennomicrus, Cephennula, Lathomicrus, Pomphopsilla, Cephennococcus, Trurlia, Trichokrater and two undescribed Oriental genera known from females only; this distinct and well‐supported lineage is a sister group of Cephennodes + Hlavaciellus. The genus Cephennomicrus represented in the analysis by species belonging to three previously postulated species groups is not monophyletic, and a comprehensive study comprising more taxa is necessary to reclassify this heterogeneous group.     

Infants' exploration of scented toys: effects of prior experiences

To evaluate breastfed infants' responses to scented objects, we videotaped the facial and bodily reactions of sixty-three infants as they explored, in succession, three toys that were identical in appearance but different in their characteristic odor. Two of the toys were scented with odorants previously shown to be transmitted to human milk, one with ethanol and the other with vanilla, whereas the third toy was unscented. Each videotape was subjected to frame-by-frame analysis to measure a variety of behaviors that are considered either to be exploratory in nature in that they lead to perceptual information about the object or to reflect the infants' hedonic reaction. Analyses of these behaviors revealed that the infants looked more and vocalized less in the presence of the vanilla-scented toy and spent less time manipulating the ethanol-scented toy when compared with the unscented toy. Moreover, differential exposure to the odors of ethanol and vanilla, as indicated by differential consumption of alcohol by a parent or use of vanilla-scented product by the mother, was related to differential responses to these odors. These findings suggest that human infants are able to detect and retain information about the chemical features of their environment.      

Phylogeny of a new supertribe Cephenniitae with generic review of Eutheiini and description of a new tribe Marcepaniini (Coleoptera: Staphylinidae: Scydmaeninae)

Genera of Eutheiini are reviewed and Eutheimorphus is removed from this tribe of ant‐like stone beetles (Scydmaeninae) and transferred to Cephenniini. A monogeneric Marcepaniini trib.n. is described to accommodate Marcepania gen.n. from Malaysia, with five species: M. semengohensis sp.n. (the type species of Marcepania), M. tuberculata sp.n. , M. seramaensis sp.n. , M. minutissima sp.n. and M. elongata sp.n. A phylogenetic analysis of all genera of Cephenniini, Eutheiini and Marcepaniini based on adult morphological characters resulted in recovering a well‐supported monophyletic clade Eutheiini + (Marcepaniini + Cephenniini) and these tribes are included in Cephenniitae stat.n. (Eutheiini and Cephenniini are therefore removed from Scydmaenitae). Only a weak support for monophyly of Eutheiini was found, but morphological characters allow for maintaining this presumably relic group as a separate tribe. Previously proposed monophyletic groups within Cephenniini were recovered as such, but after inclusion of Eutheimorphus, a sister taxon to the ‘Cephennomicrus group’, the latter lineage gained weak statistical support. The evolutionary history of Cephenniitae is discussed, with focus on known northern hemisphere fossils classified in Scydmaenitae and Hapsomelitae, but possibly closely allied to Cephenniitae. Establishing the supertribe Cephenniitae is the first step toward a profound reclassification of Scydmaeninae on a robust phylogenetic basis. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:B0E1B12D-9587-4C4F-A908-A12A0C424A8C .