1,755,640 research outputs found
La lamina di Demlfeld
No full textDescrizione multidisciplinare della lamina di bronzo iscritta da Demlfed, presso Anpass (A)
The Cartridge: A Canonical Neural Circuit Abstraction of the Lamina Neuropil - Construction and Composition Rules
Get PDFThe Lamina is a neuropil that resides in the optic lobe of the early visual system of the fruit fly. Its neural circuit consists of some 700~800 cartridges. A cartridge is an atomic neural circuit abstraction whose I/O behavior can be studied in isolation. The anatomy of the neurons, neurotransmitter types and connectivity patterns of the neurons in the cartridge are briefly reviewed. A circuit-level model of a cartridge suitable for implementation on a GPU platform is presented in detail. Cartridge interconnects create neural circuits with different I/O characteristics. A number of cartridge composition rules for building neural circuits with different spatial I/O characteristics are discussed. We present a model neural circuit for initial functional evaluations and scaling of the Lamina and its interconnection with the Medulla. Implementation considerations of the Lamina neural circuit are discussed.Additional documentation about Neurokernel project are available at http://neurokernel.github.i
Agrin binds to the nerve-muscle basal lamina via laminin.
Get PDFAgrin is a heparan sulfate proteoglycan that is required for the formation and maintenance of neuromuscular junctions. During development, agrin is secreted from motor neurons to trigger the local aggregation of acetylcholine receptors (AChRs) and other proteins in the muscle fiber, which together compose the postsynaptic apparatus. After release from the motor neuron, agrin binds to the developing muscle basal lamina and remains associated with the synaptic portion throughout adulthood. We have recently shown that full-length chick agrin binds to a basement membrane-like preparation called Matrigel. The first 130 amino acids from the NH2 terminus are necessary for the binding, and they are the reason why, on cultured chick myotubes, AChR clusters induced by full-length agrin are small. In the current report we show that an NH2-terminal fragment of agrin containing these 130 amino acids is sufficient to bind to Matrigel and that the binding to this preparation is mediated by laminin-1. The fragment also binds to laminin-2 and -4, the predominant laminin isoforms of the muscle fiber basal lamina. On cultured myotubes, it colocalizes with laminin and is enriched in AChR aggregates. In addition, we show that the effect of full-length agrin on the size of AChR clusters is reversed in the presence of the NH2-terminal agrin fragment. These data strongly suggest that binding of agrin to laminin provides the basis of its localization to synaptic basal lamina and other basement membranes
Projection neurons in lamina III of the rat spinal cord are selectively innervated by local dynorphin-containing excitatory neurons
Get PDFLarge projection neurons in lamina III of the rat spinal cord that express the neurokinin 1 receptor are densely innervated by peptidergic primary afferent nociceptors and more sparsely by low-threshold myelinated afferents. However, we know little about their input from other glutamatergic neurons. Here we show that these cells receive numerous contacts from nonprimary boutons that express the vesicular glutamate transporter 2 (VGLUT2), and form asymmetrical synapses on their dendrites and cell bodies. These synapses are significantly smaller than those formed by peptidergic afferents, but provide a substantial proportion of the glutamatergic synapses that the cells receive (over a third of those in laminae I–II and half of those in deeper laminae). Surprisingly, although the dynorphin precursor preprodynorphin (PPD) was only present in 4–7% of VGLUT2 boutons in laminae I–IV, it was found in 58% of the VGLUT2 boutons that contacted these cells. This indicates a highly selective targeting of the lamina III projection cells by glutamatergic neurons that express PPD, and these are likely to correspond to local neurons (interneurons and possibly projection cells). Since many PPD-expressing dorsal horn neurons respond to noxious stimulation, this suggests that the lamina III projection cells receive powerful monosynaptic and polysynaptic nociceptive input. Excitatory interneurons in the dorsal horn have been shown to possess IA currents, which limit their excitability and can underlie a form of activity-dependent intrinsic plasticity. It is therefore likely that polysynaptic inputs to the lamina III projection neurons are recruited during the development of chronic pain states
nicholasjchua/megaphragma-lamina: resubmission_230708
No full textData and Jupyter notebooks for:
A complete reconstruction of the early visual system of an adult insect (2023)
Nicholas J. Chua, Anastasia A. Makarova, Pat Gunn, Sonia Villani, Ben Cohen, Myisha Thasin, Jingpeng Wu, Deena Shefter, Song Pang, C. Shan Xu, Harald Hess, Alexey A. Polilov, Dmitri B. Chklovskii
Electron microscopy data and lamina neuron reconstructions are available on https://waspem-lamina.flatironinstitute.or
Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells
No full textThe Lamina-associated polypeptide two (LAP2) proteins comprising three human isoforms, LAP2 +- LAP2β and LAP2 have been shown to provide a structural framework in the nucleus and to facilitate nuclear assembly and disassembly during the cell cycle. Expression profiling studies, using microarrays, identified elevated levels of LAP2α in cervical cancer patient material compared to normal. Altered expression of LAP2 may thus have significance in the development of certain cancers. The aim of this project was thus to independently confirm the up-regulation of LAP2α in cancer material and to determine the effect of inhibiting its expression on the biology of cancer and transformed cells. LAP2α mRNA and protein expression was shown to be elevated in cervical cancer tissue compared to normal cervical tissue by Real-time RT-PCR and immunohistochemical analysis respectively. Interestingly, LAP2 (both the LAP2α and LAP2β isoforms) was shown to be overexpressed in cervical cancer cell lines compared to a normal primary cervical epithelial cell line. Higher LAP2 expression appears to associate with cellular transformation as increased expression was observed in transformed human fibroblast cells compared to normal fibroblasts. LAP2 expression was also elevated in oesophageal cancer cell lines compared to normal suggesting that the overexpression of LAP2 associates with multiple cancer types. In order to determine the role of LAP2 in cancer cell biology, its expression was inhibited using specific siRNA molecules. Inhibition of LAP2 did not have an effect on adherent cell proliferation; however under anchorage-independent growth conditions a significant decrease in cell proliferation and colony formation was observed in LAP2 knockdown cells. This was accompanied by a decrease in cyclin D1 levels and an increase in p16 levels in LAP2 siRNA transfected cells. Our results did not conclusively show xiii that this decrease in proliferation was as a result of an alteration in the cell cycle profile or due to an increase in apoptosis. In addition, inhibition of LAP2 expression resulted in a decrease in Rb protein expression. It is proposed that LAP2 plays a role in stabilizing the Rb protein, as inhibition of LAP2 expression did not affect Rb mRNA levels but substantially reduced the protein half-life. In summary, increased LAP2 expression associates with transformed and cancer cells and suggests potential for use as a cancer biomarker. Its potential as an anti-cancer therapeutic, however requires further investigation
LAMINA: a tool for rapid quantification of leaf size and shape parameters-0
No full textComparison of leaf area data generated using ImageJ and LAMINA.<p><b>Copyright information:</b></p><p>Taken from "LAMINA: a tool for rapid quantification of leaf size and shape parameters"</p><p>http://www.biomedcentral.com/1471-2229/8/82</p><p>BMC Plant Biology 2008;8():82-82.</p><p>Published online 22 Jul 2008</p><p>PMCID:PMC2500018.</p><p></p
Nondirected axonal growth on basal lamina from avian embryonic neural retina
Get PDFThe vitreous surface of the embryonic avian retinal neuroepithelium was isolated by mechanical disruption of the retina mounted between 2 adhesive substrata. The 200-micron-thick sheath covered an area of up to 1 cm2 and consisted of the vitreal basal lamina with a lamina densa, 2 laminae rarae, and a carpet of ventricular cell endfeet on top of the lamina. The vitreal endfeet were removed by detergent treatment and an extracellular basal lamina was obtained. The laminae were further characterized by immunohistochemistry and immunoblotting. A 190 kDa laminin protein was detected in laminae with and without vitreal endfeet, whereas the membrane-bound neural cell adhesion molecule (N- CAM) was detectable only on the endfeet of the ventricular cells and was absent in the detergent-treated basal laminae. Neither immunoblotting nor immunostaining revealed fibronectin in these preparations. Explants of retina, sensory ganglia, and cerebellum from chick, quail, and mouse were cultured on the basal lamina as a substratum. In all cases axonal outgrowth was excellent, with a growth rate similar to that in situ. Outgrowing axons from sensory ganglia and cerebellar explants were accompanied by migratory cells, which, in the case of sensory ganglia, were flat cells and, in the case of cerebellar explants, resembled granular neurons. Optic axons grew on the laminae in an asymmetric, explant-inherent pattern specific for the position of origin of the explant. On detergent-treated basal laminae, as well as on laminin, the retinal axons grew in a clockwise orientation. This axonal growth pattern was specific for retinal tissue and was not observed with axons from other neural explants. In spite of the excellent substrate properties provided by the substratum, cues for growing axons (toward or away from the optic disk) were not detectable in the basal lamina preparations
Allometric relationships between lamina area, lamina mass and petiole mass of 93 temperate woody species vary with leaf habit, leaf form and altitude
No full text1. The allometric scaling relationship between lamina and lamina support has rarely been examined, such that its significance to plant life-history strategies has not been fully explored and understood so far. We investigated the sizes of leaf lamina and petiole for 93 temperate broad-leaved woody species at two altitudes of a southwestern mountain, and analysed the scaling relationship in relation to leaf habit (evergreen vs. deciduous), leaf form (simple- vs. compound-leaved species), and habitat type (low vs. high altitude). 2. Significant allometric scaling relationships were found between petiole mass and lamina mass, and between petiole mass and lamina area, with common slopes of 0.872 and 0.742, respectively, both significantly departed from the value of 1.0. The results of phylogenetic comparative analyses were in accordance with the observed positive scaling relationships. 3. The evergreen species were found to have a greater petiole mass than the deciduous at a given lamina area; whilst a contrasting pattern was observed between lamina mass and petiole mass, in which the evergreens had a greater biomass allocation to lamina for the same petiole mass relative to the deciduous. 4. The compound-leaved species were observed to be significantly greater in both lamina area and lamina support (including petioles, rachis and petiolules) than the simple-leaved species, whereas the former had a smaller lamina area or lamina mass at a given petiole mass than the latter. 5. The plants from the high altitude had less lamina area at a given petiole investment compared to those from the lower altitude, likely due to the large mechanic and transporting requirements of petioles in the species at high altitude. 6. Our results indicate that petioles serve as an adverse forcing on the maximization of lamina area and lamina biomass and that the allometric relationship between lamina and lamina support varies with leaf habit, leaf form and habitat
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