bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synaptic specializations exist between enteric motor nerves and interstitial cells of Cajal in the murine stomach
Authors: Beckett Elizabeth A.H. , Takeda Yukari , Yanase Haruko , Sanders Kenton M. , Ward Sean M. 
Published: October 2005

AbstractAutonomic neurotransmission is thought to occur via a loose association between nerve varicosities and smooth muscle cells. In the gastrointestinal tract ultrastructural studies have demonstrated close apposition between enteric nerves and intramuscular interstitial cells of Cajal (ICC‐IM) in the stomach and colon and ICC in the deep muscular plexus (ICC‐DMP) of the small intestine. In the absence of ICC‐IM, postjunctional neural responses are compromised. Although membrane specializations between nerves and ICC‐IM have been reported, the molecular identity of these specializations has not been studied. Here we have characterized the expression and distribution of synapse‐associated proteins between nerve terminals and ICC‐IM in the murine stomach. Transcripts for the presynaptic proteins synaptotagmin, syntaxin, and SNAP‐25 were detected. Synaptotagmin and SNAP‐25‐immunopositive nerve varicosities were concentrated in varicose regions of motor nerves and were closely apposed to ICC‐IM but not smooth muscle. W/WV mice were used to examine the expression and distribution of synaptic proteins in the absence of ICC‐IM. Transcripts encoding synaptotagmin, syntaxin, and SNAP‐25 were detected in W/WV tissues. In the absence of ICC‐IM, synaptotagmin and SNAP‐25 were localized to nerve varicosities. Reverse transcriptase polymer chain reaction (RT‐PCR) and immunohistochemistry demonstrated the expression of postsynaptic density proteins PSD‐93 and PSD‐95 in the stomach and expression levels of PSD‐93 and PSD‐95 were reduced in W/WV mutants. These data support the existence of synaptic specializations between enteric nerves and ICC‐IM in gastric tissues. In the absence of ICC‐IM, components of the synaptic vesicle docking and fusion machinery is trafficked and concentrated in enteric nerve terminals. J. Comp. Neurol. 493:193–206, 2005. © 2005 Wiley‐Liss, Inc.
Dual, multilayered somatosensory maps formed by antennal tactile and contact chemosensory afferents in an insect brain
Authors: Nishino Hiroshi , Nishikawa Michiko , Yokohari Fumio , Mizunami Makoto 
Published: October 2005

AbstractThe antennae of most insects move actively and detect the physical and chemical composition of objects encountered by using their associated tactile sensors. Positional information is required for these sensory modalities to interpret the physical environment. Although we have a good understanding of antennal olfactory pathways, little is known about the destinations of antennal mechanosensory and contact chemosensory (gustatory) receptor neurons in the central nervous system. The cockroach Periplaneta is equipped with a pair of long, thin antennae, which are covered in bristles. The distal portions of each antenna possess about 6,500 bimodal bristles that house one tactile sensory and one to four contact chemosensory neurons. In this study, we investigated the morphologies of bimodal bristle receptor afferents by staining individual or populations of bristles. Unlike olfactory afferents, which project exclusively into the glomeruli in the ventral region of the deutocerebrum, both the presumptive mechanosensory and the contact chemosensory afferents projected into the posterior dorsal region of the deutocerebrum and the anterior region of the subesophageal ganglion. Each afferent showed multilayered segmentation and spatial occupation reflecting its three‐dimensional position in the periphery. Presumptive contact chemosensory afferents, characterized by their thin axons and unique branching pattern, occupied more medioventral positions compared with the presumptive tactile afferents. Furthermore, projection fields of presumptive contact chemosensory afferents from single sensilla tended to be segregated from each other. These observations suggest that touch and taste positional information from the antenna is precisely represented in primary centers in a modality‐specific manner. J. Comp. Neurol. 493:291–308, 2005. © 2005 Wiley‐Liss, Inc.
Morphological impairments in retinal neurons of the scotopic visual pathway in a monkey model of Parkinson's disease
Authors: Cuenca Nicolás , Herrero María‐Trinidad , Angulo Antonia , de Juan Emilio , Martínez‐Navarrete Gema C. , López Salvador , Barcia Carlos , Martín‐Nieto José 
Published: October 2005

AbstractPhysiological abnormalities resulting from death of dopaminergic neurons of the central nervous system in Parkinson's disease also extend to the retina, resulting in impaired visual functions. In both parkinsonian patients and animal models, low levels of dopamine and loss of dopaminergic cells in the retina have been reported. However, the morphology and connectivity of their postsynaptic neurons, the amacrine cells, have not been analyzed. Here we report, with macaques chronically treated with 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) as a model of Parkinson's disease, that morphological impairments in dopaminergic retinal neurons and their plexus in the inner retina are accompanied by an immunoreactivity decrease in γ‐aminobutyric acidergic and glycinergic amacrine cells. Especially deteriorated were AII amacrine cells, the main neuronal subtype postsynaptic to dopaminergic cells, which exhibited a marked loss of lobular appendages and dendritic processes. Concomitantly, electrical synapses among AII cells, as well as chemical synapses between these and rod bipolar cells, were highly deteriorated in parkinsonian monkeys. These results highlight that the scotopic visual pathway is severely impaired in the parkinsonian condition and provide a morphological basis for a number of abnormalities found in electrophysiological and psychophysical trials in Parkinson's disease patients and animal models. J. Comp. Neurol. 493:261–273, 2005. © 2005 Wiley‐Liss, Inc.
Comparison of α2 nicotinic acetylcholine receptor subunit mRNA expression in the central nervous system of rats and mice
Authors: Ishii Katsuyoshi , Wong Jamie K. , Sumikawa Katumi 
Published: October 2005

AbstractThe nicotinic acetylcholine receptor (nAChR) α2 subunit was the first neuronal nAChR to be cloned. However, data for the distribution of α2 mRNA in the rodent exists in only a few studies. Therefore, we investigated the expression of α2 mRNA in the rat and mouse central nervous systems using nonradioactive in situ hybridization histochemistry. We detected strong hybridization signals in cell bodies located in the internal plexiform layer of the olfactory bulb, the interpeduncular nucleus of the midbrain, the ventral and dorsal tegmental nuclei, the median raphe nucleus of the pons, the ventral part of the medullary reticular nucleus, the ventral horn in the spinal cord of both rats and mice, and in a few Purkinje cells of rats, but not of mice. Cells that moderately express α2 mRNA were localized to the cerebral cortex layers V and VI, the subiculum, the oriens layer of CA1, the medial septum, the diagonal band complex, the substantia innominata, and the amygdala of both animals. They were also located in a few midbrain nuclei of rats, whereas in mice they were either few or absent in these areas. However, in the upper medulla oblongata α2 mRNA was expressed in several large neurons of the gigantocellular reticular nucleus and the raphe magnus nucleus of mice, but not of rats. The data obtained show that a similar pattern of α2 mRNA expression exists in both rats and mice, with the exception of a few regions, and provide the basis for cellular level analysis. J. Comp. Neurol. 493:241–260, 2005. © 2005 Wiley‐Liss, Inc.
Neuronal architecture of the mosquito deutocerebrum
Authors: Ignell Rickard , Dekker Teun , Ghaninia Majid , Hansson Bill S. 
Published: October 2005

AbstractMosquito behavior is heavily dependent on olfactory and mechanosensory cues, which are detected by receptor neurons on the antenna and on the palps. Recent progress in mosquito sensory genomics highlights the need for an up‐to‐date understanding of the neural architecture of the mosquito brain. Here we present a detailed description of the neural structure of the primary target of the majority of these neurons, the deutocerebrum, in the African malaria (Anopheles gambiae) and yellow fever (Aedes aegypti) mosquitoes. Special focus is made on the olfactory system, the antennal lobe (AL), where we present high‐resolution three‐dimensional models of the ALs of male and female Ae. aegypti. These models reveal a sexual dimorphism in the number of glomeruli, 49 and 50 glomeruli in male and female mosquitoes, respectively, and in the size of several of the identified glomeruli. The fine structure of receptor neuron terminations in the AL and the rest of the deutocerebrum is described, as are the arborizations of intrinsic deutocerebral neurons and neurons providing output to higher brain areas. In the AL a specific and very large center receiving input from the mechanosensory Johnston's organ is revealed as a multilobed structure receiving peripheral input according to a somatotopic pattern. Within the antennal nerve a specific neuropil containing early, bouton‐like ramifications of receptor neurons is described. Within the glomerular array of the AL, neurons providing a possible feedback circuit to antennal receptor neurons are shown. With these results we provide a new resolution in mosquito deutocerebral architecture. J. Comp. Neurol. 493:207–240, 2005. © 2005 Wiley‐Liss, Inc.
Buried alive: How osteoblasts become osteocytes
Authors: Franz‐Odendaal Tamara A. , Hall Brian K. , Witten P. Eckhard 
Published: October 2005

AbstractDuring osteogenesis, osteoblasts lay down osteoid and transform into osteocytes embedded in mineralized bone matrix. Despite the fact that osteocytes are the most abundant cellular component of bone, little is known about the process of osteoblast‐to‐osteocyte transformation. What is known is that osteoblasts undergo a number of changes during this transformation, yet retain their connections to preosteoblasts and osteocytes. This review explores the osteoblast‐to‐osteocyte transformation during intramembranous ossification from both morphological and molecular perspectives. We investigate how these data support five schemes that describe how an osteoblast could become entrapped in the bone matrix (in mammals) and suggest one of the five scenarios that best fits as a model. Those osteoblasts on the bone surface that are destined for burial and destined to become osteocytes slow down matrix production compared to neighbouring osteoblasts, which continue to produce bone matrix. That is, cells that continue to produce matrix actively bury cells producing less or no new bone matrix (passive burial). We summarize which morphological and molecular changes could be used as characters (or markers) to follow the transformation process. Developmental Dynamics 235:176–190, 2006. © 2005 Wiley‐Liss, Inc.
The 5′ zebrafish scl promoter targets transcription to the brain, spinal cord, and hematopoietic and endothelial progenitors
Authors: Jin Hao , Xu Jin , Qian Feng , Du Linsen , Tan Chee Yong , Lin Zhixin , Peng Jinrong , Wen Zilong 
Published: October 2005

AbstractThe stem cell leukemia (SCL) gene encodes a basic helix–loop–helix transcription factor and is essential for embryonic angiogenesis, hematopoietic stem cell specification, and erythrocyte maturation. Here, we report the isolation and characterization of the zebrafish scl promoter. We show that a 5‐kilobase (kb) genomic fragment immediately upstream of the translation start site is capable of targeting the enhanced green fluorescence protein (EGFP) expression to the anterior and posterior lateral mesoderm where the endogenous scl normally expresses. Detailed analysis of the stable transgenic fish reveals that this 5‐kb upstream sequence is sufficient to direct the EGFP transcription to the brain, spinal cord, and hematopoietic–endothelial progenitors, possibly the hemangioblast, but not primitive erythrocyte, suggesting that the zebrafish scl transcription in hematopoietic–endothelial progenitors and erythrocyte is regulated by distinct cis element(s). Our study has defined the cis regulatory element(s) for zebrafish scl expression in the brain, spinal cord, and hematopoietic–endothelial progenitors and established a valuable transgenic line Tg(5′5kbscl:EGFP) for studying hematopoietic lineage development. Developmental Dynamics 235:60–67, 2006. © 2005 Wiley‐Liss, Inc.
PINCH‐1 expression during early avian embryogenesis: Implications for neural crest and heart development
Authors: Martinsen Brad J. , Neumann Ann N. , Frasier Allison J. , Baker Clare V.H. , Krull Catherine E. , Lohr Jamie L. 
Published: October 2005

AbstractThe invasion of the cardiac neural crest (CNC) into the outflow tract (OFT) and subsequent OFT septation are critical events during vertebrate heart development. We previously had performed four modified differential display (DD) screens in the chick embryo to identify genes that may be involved in CNC and heart development. Full‐length sequence of one of the DD clones has been obtained and identified as chick PINCH‐1. This particularly interesting new cysteine‐histidine–rich protein contains five protein‐binding LIM domains (five double zinc fingers), a nuclear localization signal, and a nuclear export signal, allowing it to participate in integrin and growth factor signaling and possibly act as a transcription factor. We show here for the first time that chick PINCH‐1 is expressed in neural crest cells, both in the neural fold and cardiac OFT, and is also expressed in mesoderm derived‐structures, including the myocardium, during avian embryogenesis. The normal expression pattern and overexpression in neural crest cell explants suggest that PINCH‐1 may be a regulator of neural crest cell adhesion and migration. Developmental Dynamics 235:152–162, 2006. © 2005 Wiley‐Liss, Inc.
Establishment and maintenance of planar epithelial cell polarity by asymmetric cadherin bridges: A computer model
Authors: Le Garrec Jean‐François , Lopez Philippe , Kerszberg Michel 
Published: October 2005

AbstractAnimal scales, hairs, feathers, and cilia are oriented due to cell polarization in the epithelial plane. Genes involved have been identified, but the signal and mechanism remain unknown. In Drosophila wing polarization, the action of a gradient of Frizzled activity is widely assumed; and cell–cell signalling by cadherins such as Flamingo surely plays a major role. We present a computer model where reading the Frizzled gradient occurs through biased, feedback‐reinforced formation of Flamingo‐based asymmetric intercellular complexes. Through these complexes neighboring cells are able to compare their Frizzled activity levels. Our computations are highly noise‐resistant and reproduce both wild‐type and all known mutant wing phenotypes; other phenotypes are predicted. The model puts stringent limits on a Frizzled activation signal, which should exhibit unusual properties: (1) the extracellular Frizzled signalling gradient should be counterdirectional—decreasing from proximal (P) to distal (D), whereas during polarization, the intracellular Frizzled gradient builds up from P to D; (2) the external gradient should be relatively weak and short‐lived, lest it prevent inversion of intracellular Frizzled. These features, largely independent of model details, may provide useful clues for future experimental efforts. Developmental Dynamics 235:235–246, 2006. © 2005 Wiley‐Liss, Inc.
A novel mutant phenotype implicates dicephalic in cyst formation in the Drosophila ovary
Authors: McCaffrey Ruth , St Johnston Daniel , González‐Reyes Acaimo 
Published: October 2005

AbstractThe establishment of polarity in Drosophila requires the correct specification of the oocyte in early stages of oogenesis, its positioning at the posterior of the egg chamber, and signalling events between the oocyte and the adjacent posterior follicle cells. As a consequence, the anterior‐posterior and the dorsal‐ventral axes are fixed. The posterior localisation of the oocyte depends on cadherin‐mediated adhesion between the oocyte and the follicle cells. Here we show that dicephalic mutants affect the posterior positioning of the oocyte without interfering with oocyte specification in the germarium. Unlike other mutants that also affect the posterior placement of the oocyte, dicephalic mutants affect neither gurken expression nor karyosome formation during meiosis. By analysing in detail the mutant phenotypes of dicephalic, we find that cyst formation in mutant germaria is defective and that it shares some similarities with cysts that lack DE‐cadherin in the germline cells. We propose a model in which dicephalic is involved in the proper adhesion between the oocyte and the somatic follicle cells. Developmental Dynamics 235:908–917, 2006. © 2005 Wiley‐Liss, Inc.
Expression patterns of Wnt genes during development of an anterior part of the chicken eye
Authors: Fokina Valentina M. , Frolova Elena I. 
Published: October 2005

AbstractTo address the roles of Wnts in the development of the anterior eye, we used a chicken model to perform comprehensive expression analysis of all Wnt genes during anterior eye development. In analyzing the available genomic sequences, we found that the chicken genome encodes 18 Wnt proteins that are homologous to corresponding human and mouse proteins. The mRNA sequences for 12 chicken Wnt genes are available in GenBank, and mRNAs for six other Wnt genes (Wnt2, Wnt5b, Wnt7b, Wnt8b, Wnt9b, and Wnt16) were identified and cloned based on the homology to the genes from other species. In addition, we found that chicken Wnt3a and Wnt7b genes encode two alternative mRNA isoforms containing different first exons. Following in situ hybridization, we found that out of 18 Wnt genes, 11 genes were expressed in the anterior eye, exhibiting distinct temporal‐spatial patterns. Several Wnts were expressed in the lens, including Wnt2 and Wnt2b in the anterior epithelium and Wnt5a, Wnt5b, Wnt7a, and Wnt7b in the differentiating lens fiber cells. In the cornea, we detected Wnt3a, Wnt6, and Wnt9b in the ocular surface ectoderm, including the corneal epithelium, and Wnt9a in the corneal endothelium from the onset of its differentiation. In the optic cup, Wnt2, Wnt2b, and Wnt9a were localized in the rim of the optic cup (presumptive iris), while Wnt5a and Wnt16 were detected in the ciliary epithelium/iris zone of the differentiated optic cup, and Wnt6 was expressed in the iridial mesenchyme. These data suggest that Wnt signaling might play important roles in anterior eye development. Developmental Dynamics 235:496–505, 2006. © 2005 Wiley‐Liss, Inc.
Epithelial transformations in the establishment of the blood–gas barrier in the developing chick embryo lung
Authors: Makanya A.N. , Hlushchuk R. , Duncker H.‐R. , Draeger A. , Djonov V. 
Published: October 2005

AbstractThe tall epithelium of the developing chick embryo lung is converted to a squamous one, which participates in formation of the thin blood–gas barrier. We show that this conversion occurred through processes resembling exocrine secretion. Initially, cells formed intraluminal protrusions (aposomes), and then transcellular double membranes were established. Gaps between the membranes opened, thus, severing the aposome from the cell. Alternatively, aposomes were squeezed out by adjacent cells or were spontaneously constricted and extruded. As a third mechanism, formation and fusion of severed vesicles or vacuoles below the aposome and their fusion with the apicolateral plasma membrane resulted in severing of the aposome. The atria started to form by progressive epithelial attenuation and subsequent invasion of the surrounding mesenchyme at regions delineated by subepithelial α‐smooth muscle actin–positive cells. Further epithelial attenuation was achieved by vacuolation; rupture of such vacuoles with resultant numerous microfolds and microvilli, which were abscised to accomplish a smooth squamous epithelium just before hatching. Developmental Dynamics 235:68–81, 2006. © 2005 Wiley‐Liss, Inc.
Spatio‐temporal expression of MRF4 transcripts and protein during Xenopus laevis embryogenesis
Authors: Della Gaspera Bruno , Sequeira Ines , Charbonnier Frederic , Becker Christel , Shi De‐Li , Chanoine Christophe 
Published: October 2005

AbstractWhereas there have been extensive studies of the expression of XMyf5 and XMyoD during Xenopus embryogenesis, nothing is known about the spatio‐temporal accumulation of XMRF4 transcripts and protein. In this report, we describe the cloning and characterization of two full‐length MRF4 cDNAs and of their proximal promoters in Xenopus laevis. The comparison of the relative transcript levels of the XMRF4‐a and ‐b genes in developing and adult muscles is highly suggestive of specific functions for the corresponding XMRF4 proteins. Whole‐mount embryo in situ hybridization revealed the first XMRF4 transcripts in the more differentiated anterior myocytes of the embryo when the myosin heavy chain E3 mRNA begins to be detectable. XMRF4 mRNA accumulation later extended posteriorly but was never detected in the posterior unsegmented mesoderm, in contrast to XMyoD and XMyf‐5. Whole‐mount embryo immunohistochemistry revealed that XMRF4 protein accumulated in somite nuclei slightly after XMRF4 transcripts. Developmental Dynamics 235:524–529, 2006. © 2005 Wiley‐Liss, Inc.
Transforming growth factor‐β induces loss of epithelial character and smooth muscle cell differentiation in epicardial cells
Authors: Compton Leigh A. , Potash Dru A. , Mundell Nathan A. , Barnett Joey V. 
Published: October 2005

AbstractDuring embryogenesis, epicardial cells undergo epithelial–mesenchymal transformation (EMT), invade the myocardium, and differentiate into components of the coronary vasculature, including smooth muscle cells. We tested the hypothesis that transforming growth factor‐β (TGFβ) stimulates EMT and smooth muscle differentiation of epicardial cells. In epicardial explants, TGFβ1 and TGFβ2 induce loss of epithelial morphology, cytokeratin, and membrane‐associated Zonula Occludens‐1 and increase the smooth muscle markers calponin and caldesmon. Inhibition of activin receptor‐like kinase (ALK) 5 blocks these effects, whereas constitutively active (ca) ALK5 increases cell invasion by 42%. Overexpression of Smad 3 did not mimic the effects of caALK5. Inhibition of p160 rho kinase or p38 MAP kinase prevented the loss of epithelial morphology in response to TGFβ, whereas only inhibition of p160 rho kinase blocked TGFβ‐stimulated caldesmon expression. These data demonstrate that TGFβ stimulates loss of epithelial character and smooth muscle differentiation in epicardial cells by means of a mechanism that requires ALK5 and p160 rho kinase. Developmental Dynamics 235:82–93, 2006. © 2005 Wiley‐Liss, Inc.