The morphology of the vertical and transverse intrinsic musculature of the tongue in the 15-week human fetus

The attachments, courses and interrelationships of the transverse and vertical intrinsic muscle masses of the tongue were examined in 28 fifteen-week fetal specimens. Observations were made from 30-micron sections cut through the tongue in one of the three standard planes of section. Both sets of muscululature are qualitatively well-developed by this time period in fetal life. The transverse fibers were found to occupy the entire length of the tongue. They attach to the lamina propria of the lateral aspect of the body of the tongue and, in the root, to perimysial and adventitial connective tissue. In addition, some fibers were observed to be confluent with the mm. palatoglossus, tonsilloglossus and pharyngis superior. Medially, transverse fibers were found for the most part to terminate in the dense ventral aspect of the median septum. Vertical fibers are present from a point slightly posterior to the tip of the tongue to the level of the foramen cecum, beyond which they become sparse. All vertical fibers attach superiorly to the dorsal lamina propria. In the free part of the body, their ventral attachment, likewise, is to lamina propria. In the middle part of the tongue and, to a greater extent, in the root (as the inferior and lateral free surface decreases) these fibers attach in either the fascial plane underlying the transverse component or to the perimysium of longitudinally-running muscle bundles.     

Sprouty2 attenuates epidermal growth factor receptor ubiquitylation and endocytosis,and consequently enhances Ras/ERK signalling

Drosophila Sprouty (dSpry) was genetically identified as a novel antagonist of fibroblast growth factor receptor (FGFR), epidermal growth factor receptor (EGFR) and Sevenless signalling, ostensibly by eliciting its response on the Ras/MAPK pathway. Four mammalian sprouty genes have been cloned, which appear to play an inhibitory role mainly in FGF- mediated lung and limb morphogenesis. Evidence is presented herein that describes the functional implications of the direct association between human Sprouty2 (hSpry2) and c-Cbl, and its impact on the cellular localization and signalling capacity of EGFR. Contrary to the consensus view that Spry2 is a general inhibitor of receptor tyrosine kinase signalling, hSpry2 was shown to abrogate EGFR ubiquitylation and endocytosis, and sustain EGF-induced ERK signalling that culminates in differentiation of PC12 cells. Correlative evidence showed the failure of hSpry2DeltaN11 and mSpry4, both deficient in c-Cbl binding, to instigate these effects. hSpry2 interacts specifically with the c-Cbl RING finger domain and displaces UbcH7 from its binding site on the E3 ligase. We conclude that hSpry2 potentiates EGFR signalling by specifically intercepting c-Cbl-mediated effects on receptor down-regulation.     

E3 ubiquitin ligase Cbl-b regulates Pten via Nedd4 in T cells independently of its ubiquitin ligase activity

E3 ubiquitin ligase Cbl-b plays a crucial role in T cell activation and tolerance induction. However, the molecular mechanism by which Cbl-b inhibits T cell activation remains unclear. Here, we report that Cbl-b does not inhibit PI3K but rather suppresses TCR/CD28-induced inactivation of Pten. The elevated Akt activity in Cbl-b(-/-) T cells is therefore due to heightened Pten inactivation. Suppression of Pten inactivation in T cells by Cbl-b is achieved by impeding the association of Pten with Nedd4, which targets Pten K13 for K63-linked polyubiquitination. Consistent with this finding, introducing Nedd4 deficiency into Cbl-b(-/-) mice abrogates hyper-T cell responses caused by the loss of Cbl-b. Hence, our data demonstrate that Cbl-b inhibits T cell activation by suppressing Pten inactivation independently of its ubiquitin ligase activity.     

Posttetanic potentiation and presynaptically induced long-term potentiation at the mossy fiber synapse in rat hippocampus

A form of long-term potentiation (LTP) is induced at the mossy fiber (MF) synapse in the hippocampus by highfrequency presynaptic stimulation (HFS). It is generally accepted that induction of this form of LTP (MF LTP) does not depend on postsynaptic Ca²⁺ current gated by N-methyl-D -aspartate receptors, but it has remained controversial whether induction depends on postsynaptic depolarization and voltage-gated entry of Ca²⁺. There are also contradictory data on the time course of both LTP and post-tetanic potentiation (PTP), a shorter duration form of potentiation observed at MF synapses immediately following HFS. It has been proposed that some of these differences in results may have arisen because of difficulties in isolating monosynaptic responses to MF input. In the present study, whole cell recording was used to observe excitatory postsynaptic currents (EPSCs) elicited in CA3 pyramidal cells by input from MFs. Postsynaptic cells were dialyzed with 1,2-bis(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid (BAPTA) and F^? to inhibit postsynaptic mechanisms that required Ca²⁺, cells were under voltage clamp during HFS, and conditions were selected to minimize the likelihood of polysynaptic contamination. Under these conditions, HFS nevertheless induced robust LTP (mean magnitude, 62%). The possibility that EPSCs were contaminated by polysynaptic components was investigated by exposing the slices to a suppressing medium (one that partially blocked neurotransmission). EPSC waveforms did not change shape during suppression, indicating that contamination was absent. The LTP observed always was accompanied by prominent PTP that lasted through the first 5 to 15 min following HFS (mean decay time constant, 3.2 min). Induction of this LTP was not cooperative; there was no relationship between the size of responses and the magnitude of the LTP induced. LTP magnitude also was unrelated to the extent to which postsynaptic cells depolarized during HFS. These results show that high rates of presynaptic MF activity elicit robust LTP whether or not there is accompanying postsynaptic depolarization or increase in the concentration of postsynaptic Ca²⁺. High-frequency MF activity also results in a PTP that is unusually large and long. © 1995 John Wiley & Sons, Inc.     

Systematic conservation planning in the face of climate change: bet-hedging on the Columbia Plateau

Systematic conservation planning efforts typically focus on protecting current patterns of biodiversity. Climate change is poised to shift species distributions, reshuffle communities, and alter ecosystem functioning. In such a dynamic environment, lands selected to protect today's biodiversity may fail to do so in the future. One proposed approach to designing reserve networks that are robust to climate change involves protecting the diversity of abiotic conditions that in part determine species distributions and ecological processes. A set of abiotically diverse areas will likely support a diversity of ecological systems both today and into the future, although those two sets of systems might be dramatically different. Here, we demonstrate a conservation planning approach based on representing unique combinations of abiotic factors. We prioritize sites that represent the diversity of soils, topographies, and current climates of the Columbia Plateau. We then compare these sites to sites prioritized to protect current biodiversity. This comparison highlights places that are important for protecting both today's biodiversity and the diversity of abiotic factors that will likely determine biodiversity patterns in the future. It also highlights places where a reserve network designed solely to protect today's biodiversity would fail to capture the diversity of abiotic conditions and where such a network could be augmented to be more robust to climate-change impacts.     

High titres of antibody to murine leukaemia virus in lymphocyte (Ly) alloantisera

The radioimmune precipitation (RIP) assay was used to examine the antibody titres against endogenous AKR murine leukaemia virus (MuLV) in a number of antisera to lymphocyte (Ly) alloantigens. The sera from normal donor and unimmunized recipient mice used in raising the alloantisera were also examined for anti-MuLV activity. It was found that all the antisera had high anti-MuLV titres and that in all but one case alloantigen immunization augmented the anti-viral titres. The degree of augmentation did not appear to be related to the anti-MuLV titre in the donor strain sera. Three I-region antisera were also examined for anti-MuLV antibodies and were found to have lower anti-viral titres than the Ly antisera even though immunization to I-region products greatly augmented the anti-viral titre. These results caution against the use of Ly antisera in characterizing the phenotype of lymphoid tumour cells without prior virus absorption.     

Spinal curvature associated with Myxobolus sp. cysts in the brain of sand-flathead (Platycephalus bassensis L.)

We describe spinal curvature in sand-flathead, presumably due to cerebral myxoboliasis.

Résumé

Torsions de la colonne vertébrale associées aux cystes de Myxobolus sp. duns le cervean de Platycephalus bassensis L.
Des torsions de la colonne vertébrale chez Platycephalus bassensis L., probablement dûes sà une myxoboliasis cerébrale, sont décrites.

Zusammenfassung

Verkrümmungen der Wirbelsäule durch System von Myxobolus sp. im Gehirn des Sandflachkopfes ( Platycephalus bassensis L. )
Verkrümmungen der Wirbelsäule werden bei Platycephalus bassensis beschrieben und mit der cerebralen Myxoboliasis in Zusammenhang gebracht.     

Composite autologous-allogeneic skin replacement: development and clinical application

A major unsolved problem in skin restoration in severe burns is replacement of lost dermis. We report the development and clinical application of a composite grafting technique in which allogeneic skin is the source of dermis, and cultured autologous keratinocytes generate epidermis. Excised burn wounds are resurfaced with unmatched allograft. Immunosuppression from the burn and reduced immunoreactivity of the allograft permit successful allograft engraftment. Keratinocyte cultures are initiated from the patient. Allogeneic epidermis is removed, and the dermal bed is resurfaced with keratinocyte cultures. The allogeneic dermis promotes rapid (less than 7 days) stratification, maturation, and integration of the cultures and the synthesis of anchoring fibrils. One case followed 11 months has shown no evidence of rejection. We reason that removal of the epidermis from allograft eliminates the majority of cells constitutively expressing alloclass II antigens, leaving behind a viable allogeneic dermal bed that serves as an ideal substrate for engraftment and integration of keratinocyte cultures but does not initiate rejection.