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At least 973 records · Page 54Linked to original sources
PubMed2003

The neuroprotective effects of virally-derived caspase inhibitors p35 and crmA following a necrotic insult.

Neuronal excitotoxicity causes energetic impairment and the ensuing cell death has historically been regarded as necrotic. Recent findings, however, indicate that apoptosis may participate in excitotoxicity. Here we examined the neuroprotective mechanisms of the well-characterized viral caspase inhibitors, p35 and crmA, following domoic acid-induced excitotoxicity in hippocampal neurons. We show that though p35 and crmA rescued neurons from toxicity, they did so under conditions of negligible caspase activation and morphological apoptosis. Thus, we characterized the novel neuroprotective effects of p35 and crmA and found that they attenuated the drop in the mitochondrial potential and blunted the decline in ATP levels. These data, to our knowledge, are the first detailed descriptions of the cell death mechanisms following domoic acid treatment of neurons. Moreover, in demonstrating the previously unexplored modulation of these processes, these data underline the capacity for classically "anti-apoptotic" proteins to alter other branches of cell death processes.

Animals↗
PubMed1990

Study of the early growth and branching of Streptomyces tendae by means of an image processing system.

A method is described for directly observing submerged growth of streptomycetes, which can be easily adapted for investigations of filamentously growing fungi. The use of an image processing system allowed a fast and accurate calculation of important morphological parameters. Most of the images can be analysed on-line. Some results are presented for early growth and branching of Streptomyces tendae. It seems that mechanisms for growth of streptomycetes were the same for both solid and liquid media.

Algorithms↗
PubMed1991

Dopaminergic interplexiform cells and centrifugal fibres in the Xenopus retina.

Putative dopaminergic neurons in the Xenopus retina were identified using an immunoreaction against tyrosine hydroxylase. A single class of cell was stained whose perikaryon (12-15 microns in diameter) was located at the border of the inner nuclear and inner plexiform layers. About 2% of the stained cell bodies were located in the ganglion cell layer, but the distribution of the processes of displaced cells had the same geometry as for the majority of stained cells. Tyrosine hydroxylase-like immunoreactive perikarya gave rise to one to four stout processes that descended to the most proximal level of the inner plexiform layer, within which they branched repeatedly to generate a diffuse network of fine processes. Secondary branches ascended to the most distal sublayer of the inner plexiform layer where they ramified into fine processes that joined other fibres arising horizontally from the cell body and confined to the distal inner plexiform layer throughout their course. The diameter of the dendritic arbor of stained cells was in the range of 350-600 microns. The dense network of fine fibres within the distal inner plexiform layer was arrayed in rings that surrounded other amacrine cells; using an antiserum against glycine we found that at least some of these were glycinergic neurons. Most tyrosine hydroxylase-positive neurons emitted one or two fine ascending processes that arose from the perikaryon, traversed the inner plexiform layer and arborized within the outer plexiform layer. Additionally, fine varicose fibres arising from the sublayer 1 of the inner plexiform layer and running to the outer retina were observed. Thus, based on light microscopic criteria, dopaminergic neurons in the Xenopus retina appeared to be interplexiform cells. A few tyrosine hydroxylase-immunoreactive fibres were observed in the optic nerve, some of which entered the inner retina where they ramified, thus indicating that they were centrifugal axons. In addition, a small number of stout smooth processes were observed to traverse the entire inner nuclear layer and course laterally at the level of the photoreceptor bases. Whether this second class of ascending process arises from the tyrosine hydroxylase-like immunoreactive efferents remains to be determined. The total number of dopaminergic neurons per retina was 750-800, equivalent to an average density of 30 cells mm-2. The dendritic fields of adjacent cells strongly overlapped, with an estimated coverage factor of 4.8.

Animals↗
PubMed1994

tau Regulation of microtubule-microtubule spacing and bundling.

Tau proteins are microtubule-associated proteins that promote microtubule polymerization in vitro and in vivo. They are a family of neuronal proteins with apparent molecular weights in the range 50,000-68,000 determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Recently, a new member of this family has been described and its cDNA has been cloned. It has an apparent molecular weight of 116,000 and has been called high-molecular-weight tau (HMW tau). All the tau proteins are encoded by a single gene, which undergoes complex alternative splicing. In the present study, we have cloned into the baculovirus a cDNA fully encoding HMW tau as well as a truncated cDNA encoding a protein beginning 13 amino acids in front of the tau microtubule-binding domain. HMW tau-recombinant-virus-infected Sf9 cells overexpressed HMW tau, which induced the polymerization of microtubules and the formation of long cellular processes similar to those induced by low-molecular-weight tau (LMW tau) overexpression. Process cross sections revealed a larger spacing (approximately 35 nm) between microtubules when induced by HMW tau than when induced by LMW tau (approximately 20 nm). The truncated construct also induces processes, where microtubules were packed far more closely together (approximately 10 nm). Although branching did not occur in processes induced by intact tau S, 10% of the processes induced by the truncated tau protein branched.

Animals↗
PubMed1977

Cycloscopy and fluorescein cycloscopy of the ciliary process.

A new gonio-cycloscope that magnifies an object up to 1.5 times was designed to observe the ciliary process and chamber angle. As a result of aging, the ciliary process became hypertrophic and more branched with discoloration. Leakage of fluorescein from the ciliary process decreased as intraocular pressure artifically increased, stopping completely at 50 mm Hg or more. Water drinking accelerated fluorescein leakage, while oral glycerol diminished it.

Adolescent↗
PubMed1983

Two identified interneurons modulate the firing pattern of pacemaker bursting cells in Helix.

Two interneurons modulating the firing pattern of two endogeneous bursting neurons have been identified in the visceral ganglion. They are characterized by large depolarizing afterpotentials and doublets due to the delayed firing of a dense layer of terminal processes converging onto the axon branches from the two bursters. Firing of the terminal processes upon soma or axon stimulation needs either subthreshold depolarization of the cell or conditioning nerve stimulation acting as a gating mechanism.

Animals↗
PubMed2004

QTLs for branching, floret formation, and pre-flowering floret abortion of rice panicle in a temperate japonica x tropical japonica cross.

A large panicle with numerous florets is essential for improving rice ( Oryza sativa L.) yield. Rice panicle size is determined by such underlying morphogenetic processes as: (1) primary branch formation on the panicle axis; (2) floret formation on the primary branches (mainly determined by the secondary branch formation); and (3) pre-flowering abortion of florets in the panicle. We examined QTLs for these processes to understand how they are integrated into panicle size. We developed 106 backcross-inbred lines (BC1F4) from a cross between 'Akihikari' (a temperate japonica) and 'IRAT109' (a tropical japonica) and constructed a genetic map. One QTL detected on chromosome 2, with a large effect (R=0.30) on the number of florets per panicle, affected both primary branch formation on the panicle axis and floret formation on the primary branches. In addition, three QTLs that affect only one of these two processes were identified on chromosomes 4, 9, and 11, each having a subsidiary effect on the number of florets per panicle (R2=0.04-0.07). QTLs for pre-flowering floret abortion were detected at three different regions of the genome (chromosomes 1, 10, and 11). This is the first report on QTLs for pre-flowering floret abortion in grasses. The absence of a co-location between QTLs suggests that floret formation and abortion are not directly linked causally. These results demonstrate that studying the partitioning of panicle size into these underlying morphogenetic components would be helpful in understanding the complicated genetic control of panicle size.

Agriculture↗
PubMed1997

Rearrangements of the cytoskeleton and cell contacts induce process formation during differentiation of conditionally immortalized mouse podocyte cell lines.

Mature podocytes are among the most complex differentiated cells and possess a highly branched array of foot processes that are essential to glomerular filtration in the kidney. Such differentiated podocytes are unable to replicate and culturing of primary podocytes results in rapid growth arrest. Therefore, conditionally immortalized mouse podocyte clones (MPC) were established, which are highly proliferative when cultured under permissive conditions. Nonpermissive conditions render the majority of MPC cells growth arrested within 6 days and induce many characteristics of differentiated podocytes. Both proliferating and differentiating MPC cells express the WT-1 protein and an ordered array of actin fibers and microtubules extends into the forming cellular processes during differentiation, reminiscent of podocyte processes in vivo. These cytoskeletal rearrangements and process formation are accompanied by the onset of synaptopodin synthesis, an actin-associated protein marking specifically differentiated podocytes. In addition, focal contacts are rearranged into an ordered pattern in differentiating MPC cells. Most importantly, electrophysiological studies demonstrate that differentiated MPC cells respond to the vasoactive peptide bradykinin by changes in intracellular calcium concentration. These results suggest a regulatory role of podocytes in glomerular filtration. Taken together, these studies establish that conditionally immortalized MPC cells retain a differentiation potential similar to podocytes in vivo. Therefore, the determinative steps of podocyte differentiation and process formation are studied for the first time using an inducible in vitro model.

Animals↗
PubMed2005

Low concentrations of aggregated beta-amyloid induce neurite formation via the neurotrophin receptor p75.

Aggregated beta-amyloid (Abeta) binds to the neurotrophin receptor p75 and induces signaling. We examined this signaling process in different cell lines which express p75 either naturally (Schwannoma RN22 cells) or which are stably transfected with wild-type p75 (MDCKwt and PCNA cells) or with a truncated form of p75 comprising only extracellular and transmembrane domains (MDCKtm cells). While Abeta in higher concentrations (10-100 microM) is known to cause apoptosis via p75, our experiments focused on the effects of low concentrations of Abeta (25 nM) which may occur in early stages of Alzheimer disease. Application of Abeta caused tyrosine phosphorylation of wild-type p75 and induced the Ras-ERK pathway as has been reported for nerve growth factor (NGF). Since Ras activation and ERK phosphorylation (via MEK) could not be observed in MDCKtm cells and since they were clearly reduced in cells transfected with a p75 antisense construct, these effects should have been mediated by p75. Abeta also induced Ras and ERK activation in cerebellar neurons of 2-day-old rats which express p75 at that developmental stage but not TrkA; other Trk receptors were inhibited by K252a. In these neurons, Abeta led to quick formation, branching and elongation of processes. But while NGF distinctly promoted neurite branching and elongation, Abeta was less effective in neurite elongation and counts of small processes and of growth cones remained clearly elevated after 24-h stimulation; these peculiarities might be linked to aberrant neuronal connections reported for an animal model of Alzheimer disease. Essentially, the observed effects were mediated by interaction of Abeta and p75.

Alzheimer Disease↗
PubMed1999

Orexin A-like immunoreactivity in the rat brain.

Distribution of orexin-A-like immunoreactivity (ORX-LI) in rat brains was investigated with the use of a rabbit polyclonal antibody against the full length peptide orexin A. Virtually all the ORX-LI cell bodies were observed in the lateral hypothalamus at the level of median eminence. The large majority of ORX-LI neurons appeared spherical or fusiform, 20-30 microm in diameter and issued two to five cell processes with few secondary branchings. Numerous ORX-LI fibers were observed in subregions of the hypothalamus. ORX-LI cell processes were sparsely distributed in the cortex, hippocampus and thalamus. Many varicose ORX-LI cell processes were situated close to the 3rd and lateral ventricles, some of which appeared to be protruding into the lumen. As a corollary, orexin A may be released into the ventricles and interact with neurons in distant targets, in addition to influencing the activity of neurons with which ORX-LI axons make synaptic contacts.

Animals↗
PubMed1999

Morphometric studies of neonatal estrogen imprinting in the mature mouse prostate.

Estrogens play an important role in prostate physiology and neonatal exposure to estrogens has profound effects on the mature structure and hormonal sensitivity of rodent prostate. We aimed to determine the long-term effects of neonatal estrogens on the ductal architecture, morphology and hormonal sensitivity of the mature mouse prostate. Newborn mice (day 1-2) were administered a single injection (s.c.) of estrogens (estradiol benzoate (EB), diethylstilbestrol (DES)) with or without concomitant anti-estrogens (tamoxifen (TAM) or ICI 182 780 (ICI)) TAM or ICI alone, GnRH-antagonist (GnRH-A) or vehicle. At 7 weeks of age, ventral prostates (VP) were microdissected to estimate branch tip numbers and processed for stereologic analysis of volume fractions and diameters of various tissue components. Estrogens induced permanently reduced branching morphogenesis leading to reduced VP weights and these effects were fully reproduced by GnRH-A, consistent with an indirect effect. Stereologically, neonatal estrogens induced epithelial and stromal hyperplasia and significantly reduced (P<0.05) the diameters of VP glandular tubules and lumen compared with controls and these regressive effects were not reversed either by TAM or ICI. These studies confirm that a single neonatal dose of both DES and EB produces imprinting in the mature mouse prostate and indicate that neonatal estrogen effects involve both direct as well as indirect effects. In addition, both TAM and ICI act as partial agonists to the estrogen receptor in the ventral prostate of neonatal mouse.

Animals↗
PubMed2001

Morphology of calretinin and tyrosine hydroxylase-immunoreactive neurons in the pig retina.

The morphology of calretinin- and tyrosine hydroxylase-immunoreactive (IR) neurons in adult pig retina was studied. These neurons were identified using antibody immunocytochemistry. Calretinin immunoreactivity was found in numerous cell bodies in the ganglion cell layer. Large ganglion cells, however, were not labeled. In the inner nuclear layer, the regular distribution of calretinin-IR neurons, the inner marginal location of their cell bodies in the inner nuclear layer, and the distinctive bilaminar morphologies of their dendritic arbors in the inner plexiform layer suggested that these calretinin-IR cells were AII amacrine cells. Calretinin immunoreactivity was observed in both A-and B-type horizontal cells. Neurons in the photoreceptor cell layer were not labeled by this antibody. The great majority of tyrosine hydroxylase-IR neurons were located at the innermost border of the inner nuclear layer (conventional amacrines). The processes were monostratified and ran laterally within layer 1 of the inner plexiform layer. Some of the tyrosine hydroxylase-IR neurons were located in the ganglion cell layer (displaced amacrines). The processes of displaced tyrosine hydroxylase-IR amacrine cells were also located within layer 1 of the inner plexiform layer. Some processes of a few neurons were located in the outer plexiform layer. A very low density of neurons had additional bands of tyrosine hydroxylase-IR processes in the middle and deep layers of the inner plexiform layer. The processes of tyrosine hydroxylase-IR neurons extended radially over a wide area and formed large, moderately branched dendritic fields. These processes occasionally had varicosities and formed "dendritic rings". These results indicate that calretinin- and tyrosine hydroxylase-IR neurons represent specific neuronal cell types in the pig retina.

Animals↗
PubMed1997

A contribution by the ascending pharyngeal artery to the arterial supply of the odontoid process of the axis vertebra.

The origin of transverse arterial branches that contribute to the arterial supply of the odontoid process (dens axis) is not clear. Dissections were performed on 20 injected fetal and adult human cranio-cervical junctions to demonstrate the origin of the arteries that contribute feeding branches to the arteries supplying the neck of the odontoid process. At its termination near the anterior arch of the atlas, the ascending pharyngeal artery gave off transverse branches that anastomosed with the anterior ascending arteries to the odontoid process. It also gave off a branch that traversed the hypoglossal canal and anastomosed with the posterior ascending artery. A small branch linked the posterior ascending artery to the first transverse branch. This investigation complements previous work on the arterial supply to the odontoid process.

Adult↗
PubMed1999

Directed membrane transport is involved in process formation in cultured podocytes.

Mature glomerular visceral epithelial cells, or podocytes, are unique cells with a complex cell architecture. Characteristically, they possess a highly branched array of major processes and foot processes, which are essential for glomerular filtration in the kidney. A podocyte cell line with the potential to exhibit many features of differentiated podocytes, particularly the formation of cell processes, was recently established. In this study, it is shown that directed membrane transport is involved in process formation in cultured podocytes. The well-characterized vesicular stomatitis virus G was used as a marker protein for the biosynthetic pathway in these cells. It seems that newly synthesized vesicular stomatitis virus G is preferentially delivered into the cell processes of the podocytes, where it is colocalized with known regulators of vesicular transport from the Golgi apparatus to the plasma membrane, such as the small GTPase rab8 and the sec6/sec8 complex. To determine the role of vesicular transport in process formation, cells were treated with brefeldin A, a drug that disrupts the trafficking of post-Golgi transport vesicles. As a result, the podocytes reversibly lost their ability to form processes. These findings suggest that podocytes are dependent on a constant fresh source of lipids and proteins to form their processes.

Animals↗
PubMed1989

Immunohistochemical demonstration of neurotensin and tyrosine hydroxylase in iris nerves of the rabbit eye.

In previous studies we have provided evidence that intracameral administration of neurotensin (NT), an endogenous tridecapeptide, produces strong miosis in the rabbit. The presence of NT immunoreactivity was investigated in rabbit iris whole mounts by light microscopic immunohistochemistry, and its distribution in the iris compared to that, of tyrosine hydroxylase (TH). A few scattered NT-positive cell bodies were localized in the dilator muscle. Both, the NT cell bodies and processes appeared parallel to the muscle cells. Extensive branching of NT-containing cell processes was observed in connection with the sphincter muscle. These NT-positive fibers formed a dense, randomly oriented network throughout the sphincter muscle cells. The distribution of TH immunoreactivity was similar to that of NT-positive cell processes, except that no TH-positive cell bodies were detected in any of the iris structures examined. Moderate branching of TH-positive fibers was observed in the dilator and sphincter iris muscles. These findings provide neuroanatomical support for an important role of NT in pupillary physiology. Its similar topographical distribution with TH suggests that NT and dopamine may be co-localized, as it has already been described in brain.

Animals↗
PubMed2004

Somatomotor system of the adult amphioxus (Branchiostoma lanceolatum) revealed by an anticalretinin antiserum: An immunocytochemical study.

In a classic study with silver staining methods, the somatomotor system of the amphioxus spinal cord was described as consisting of three different types of neuron segmentally arranged in two opposite fan-shaped group types (Bone [1960] J Comp Neurol 115:27-64). The present study reports the presence of calretinin-like immunoreactivity in the somatomotor system of the amphioxus, which allows us to reevaluate old descriptions of amphioxus motoneurons. In the spinal cord, two types of calretinin-like immunoreactive (CR-ir) motoneurons, large and small, sent processes toward the ventrolateral region of the cord, where they branched and gave rise to processes coursing longitudinally in the somatomotor bundles. These processes produced a number of long and thin collaterals directed to several neuropil regions. Short collaterals were directed to the region of the neuromuscular contacts at the ventrolateral surface of the cord. The groups of CR-ir motoneurons exhibited a segmental organization and were localized only facing the myomeres, i.e., opposite to the entrance of the dorsal nerve roots, which is at variance with the above-mentioned classical report. CR-ir motoneurons were also observed in the brain between a level just rostral to the nerve III entry and nerve VI. The CR-ir somatomotor bundle ascended to the region of the neuromuscular junction of myomere 1. Additional faintly CR-ir neurons were observed in the region of the lamellate body of the brain. Our results reveal for the first time that calretinin immunoreactivity in the central nervous system of amphioxus was limited to a few types of neuron and that calretinin was not expressed in the peripheral nervous system, unlike vertebrates.

Animals↗
PubMed2006

Branch to colony trajectory in a modular organism: pattern formation in the Indo-Pacific coral Stylophora pistillata.

The architecture of the colony in a branching coral is an iterative process in which new layers of calcium carbonate compile atop existing structures that remain unchanged. Colony growth and development, known as astogeny, is believed to be a continuous process, characterized by replication of lower rank unites, polyps, and branches. This study seeks to explore the genetic blueprint of branch-to-colony developmental trajectory in the branching coral Stylophora pistillata, within an astogeny period of 1 year. One hundred small branches (initially 2-4 cm long) were sampled from 10 colonies. A year later, 63 remaining colonies were analyzed for their architectural rules by using 15 morphometric parameters. Multivariate statistical tests were preformed. Cluster and two-dimensional nonmetric Multi-Dimensional Scaling analyses revealed that the 10 genotypes could be divided into two major morphometric groups and two intermediate groups, whereas SIMPER analyses (a similarity percentage test) on within-genet similarities showed high similarity between the ramets developed from each of the 10 genotypes. Although, at first, it seemed that different colonies exhibited variable and different architectural designs (each characterized by specific morphometric parameters), a comprehensive analysis revealed that all 10 coral genotypes exhibited a single common developmental plan that was characterized by a continuum of architectural design with several distinct stages. Each stage is marked by its own characteristic morphometric parameters. Changing of developmental rules during the trajectory from branch to coral colony may help the colony to cope better with environmental constraints.

Animals↗
PubMed2005

Microbial ecology of bulking and foaming activated sludge treating tannery wastewater.

This study involves a comprehensive survey of the microbial ecology of the activated sludge process treating tannery wastewater, emphasizing evaluation during periods of bulking and foaming. The survey also includes a detailed characterization of process influent and effluent. Observations always associate bulking with significant increase in protozoa species and rotifers, but decrease or disappearance of nematodes. Activated sludge sustained under normal conditions with a sludge volume index lower than 80 ml g(-1), exhibits all the properties of a compact and healthy zoogleal floc structure. Three types of filamentous bacteria prevail in the microscopic examinations. Two of the filamentous bacteria, Microthrix parvicella and Nostocoida limicola II, always appear as components of the floc structure under normal conditions and abundant or even excessive levels. The study identifies Gordona spp. as the main microorganism responsible for bulking and foaming, which starts by a Gordona contamination process inside the floc, later branching out and extending through adjacent flocs. When completed, this process increases sludge volume index values to over 200 ml g(-1). Microscopic examinations indicate significant morphological differences between filamentous microorganisms observed in this study and reported in the literature mostly for domestic sewage treatment.

Data Collection↗