bluuebunny/crossref_metadata_2025_split huggingface dataset:
TRF2 dysfunction elicits DNA damage responses associated with senescence in proliferating neural cells and differentiation of neurons
Authors: Zhang Peisu , Furukawa Katsutoshi , Opresko Patricia L. , Xu Xiangru , Bohr Vilhelm A. , Mattson Mark P. 
Published: March 2006

AbstractTelomeres are specialized structures at the ends of chromosomes that consist of tandem repeats of the DNA sequence TTAGGG and several proteins that protect the DNA and regulate the plasticity of the telomeres. The telomere‐associated protein TRF2 (telomeric repeat binding factor 2) is critical for the control of telomere structure and function; TRF2 dysfunction results in the exposure of the telomere ends and activation of ATM (ataxia telangiectasin mutated)‐mediated DNA damage response. Recent findings suggest that telomere attrition can cause senescence or apoptosis of mitotic cells, but the function of telomeres in differentiated neurons is unknown. Here, we examined the impact of telomere dysfunction via TRF2 inhibition in neurons (primary embryonic hippocampal neurons) and mitotic neural cells (astrocytes and neuroblastoma cells). We demonstrate that telomere dysfunction induced by adenovirus‐mediated expression of dominant‐negative TRF2 (DN‐TRF2) triggers a DNA damage response involving the formation of nuclear foci containing phosphorylated histone H2AX and activated ATM in each cell type. In mitotic neural cells DN‐TRF2 induced activation of both p53 and p21 and senescence (as indicated by an up‐regulation of β‐galactosidase). In contrast, in neurons DN‐TRF2 increased p21, but neither p53 nor β‐galactosidase was induced. In addition, TRF2 inhibition enhanced the morphological, molecular and biophysical differentiation of hippocampal neurons. These findings demonstrate divergent molecular and physiological responses to telomere dysfunction in mitotic neural cells and neurons, indicate a role for TRF2 in regulating neuronal differentiation, and suggest a potential therapeutic application of inhibition of TRF2 function in the treatment of neural tumors.
Notch and NGF/p75NTR control dendrite morphology and the balance of excitatory/inhibitory synaptic input to hippocampal neurones through Neurogenin 3
Authors: Salama‐Cohen Patricia , Arévalo María‐Ángeles , Grantyn Rosemarie , Rodríguez‐Tébar Alfredo 
Published: March 2006

AbstractWe have previously shown that dendrite morphology of cultured hippocampal neurones is controlled by Notch receptor activation or binding of nerve growth factor (NGF) to its low affinity receptor p75NTR, i.e. processes that up‐regulate the expression of the Homologue of enhancer of split 1 and 5. Thus, the increased expression of these genes decreases the number of dendrites, whereas abrogation of Homologue of enhancer of split 1/5 activity stimulates the outgrowth of new dendrites. Here, we show that Neurogenin 3 is a proneural gene that is negatively regulated by Homologue of enhancer of split 1/5. It also influences dendrite morphology. Hence, a deficit of Notch or NGF/p75NTRactivation can lead to the production of high levels of Neurogenin 3, which stimulates the outgrowth of new dendrites. Conversely, activation of either Notch or p75NTR depressed Neurogenin 3 expression, which not only decreased the number of dendrites but also favoured inhibitory (GABAergic) synaptogenesis, thereby diminishing the ratios of excitatory/inhibitory inputs. NGF also augmented the levels of mRNA encoding the vesicular inhibitory amino acid transporter, but it did not affect the fraction of GAD65/67‐positive neurones. Conversely, overexpression of Neurogenin 3 largely reduced the number of inhibitory synaptic contacts and, consequently, produced a strong increase in the ratios of excitatory/inhibitory synaptic terminals. Our results reveal a hitherto unknown contribution of NGF/p75NTR to dendritic and synaptic plasticity through Neurogenin 3 signalling.
d‐Aspartate as a putative cell–cell signaling molecule in the Aplysia californica central nervous system
Authors: Miao Hai , Rubakhin Stanislav S. , Scanlan Cory R. , Wang Liping , Sweedler Jonathan V. 
Published: March 2006

AbstractThe content, synthesis and transport of d‐aspartate (d‐Asp) in the CNS of Aplysia californica is investigated using capillary electrophoresis (CE) with both laser‐induced fluorescence and radionuclide detection. Millimolar concentrations of d‐Asp are found in various regions of the CNS. In the cerebral ganglion, three adjacent neuronal clusters have reproducibly different d‐Asp levels; for example, in the F‐ and C‐clusters, up to 85% of the free Asp is present in the d‐form. Heterogeneous distribution of d‐Asp is also found in the individual identified neurons tested, including the optical ganglion top‐layer neurons, metacerebral cells, R2 neurons, and F‐, C‐ and G‐cluster neurons. The F‐cluster neurons have the highest percentage of d‐Asp (∼58% of the total Asp), whereas the lowest value of ∼8% is found in R2 neurons. In pulse‐chase experiments with radiolabeled d‐Asp, followed by CE with radionuclide detection, the synthesis of d‐Asp from l‐aspartate (l‐Asp) is confirmed. Is d‐Asp in the soma, or is it transported to distantly located release sites? d‐Asp is clearly detected in the major nerves of A. californica, including the pleuroabdominal and cerebrobuccal connectives and the anterior tentacular nerves, suggesting it is transported long distances. In addition, both d‐Asp and l‐Asp are transported in the pleuroabdominal connectives in a colchicine‐dependent manner, whereas several other amino acids are not. Finally, d‐Asp produces electrophysiological effects similar to those induced by l‐Asp. These data are consistent with an active role for d‐Asp in cell‐to‐cell communication.
Abundance of triacylglycerols in ganglia and their depletion in diabetic mice: implications for the role of altered triacylglycerols in diabetic neuropathy
Authors: Cheng Hua , Guan Shaoping , Han Xianlin 
Published: March 2006

AbstractHerein, we report the first study on the mass distribution and molecular species composition of abundant triacylglycerols (TAG) in ganglia. This study demonstrates five novel findings. First, unanticipated high levels of TAG were present in all examined ganglia from multiple species (e.g. mouse, rat and rabbit). Second, ganglial TAG mass content is location‐dependent. Third, the TAG mass levels in ganglia are species‐specific. Fourth, dorsal root ganglial TAG mass levels in streptozotocin‐induced diabetic mice are dramatically depleted relative to those found in untreated control mice. Fifth, mouse ganglial TAG mass levels decrease with age although molecular species composition is not changed. Collectively, these results indicate that TAG is an important component of ganglia and may potentially contribute to pathological alterations in peripheral neuronal function in diabetic neuropathy.
Toxicity and biodistribution of an iodine‐131‐radiolabelled tumour necrosis‐targeting antibody in non‐tumour‐bearing domestic felines
Authors: Van Walleghen D. M. , Parseghian M. H. 
Published: March 2006

AbstractThe potential of human immunotherapeutics now revolutionizing modern cancer therapy has yet to make an impact in veterinary medicine, mainly due to the evolutionary differences between human and non‐human cell surface antigens which bar the efficacy for many antibodies targeting human antigens. Here, we explore the possible use of an iodine‐131 (I‐131)‐radiolabelled chimericTNT‐1/B antibody, Cotara, being tested in humans, which targets a highly conserved structure present in all solid tumours. The goal was to document the possible toxic side‐effects, retention, excretion and biodistribution of Cotara in non‐tumour‐bearing felines. The study was conducted with six lab animal domestic shorthaired felines. Two felines were randomly placed into three dose groups: 1.5, 2.0, and 3.0 mCi kg−1(0.68, 0.9 and 1.36 mCi lb−1); these doses were administered by a single IV injection. Thyroid blockade with potassium iodide (KI) was administered orally once daily. Over the 90‐day study, haematologic test results, serum chemistry, thyroid function, food intake and morbidity were recorded. Drug distribution was ascertained through nuclear scintigraphy. Four of the six subjects had decreased appetite (Grade 1) that started on day 4 and then resolved by day 10. Two subjects exhibited intermittent days of anorexia (Grade 2) from day 5 to day 13. Both subjects with Grade 2 anorexia were sacrificed and necropsied once each exhibited two consecutive days of signs. Vomiting (Grade 2) occurred in 3 subjects from day 4 to day 13. Three subjects had moderate regenerative anaemia (Grade 2), whereas two developed leucocytosis. Overall, a single intravenous dose of Cotara resulted in moderate toxicity, with subjects exhibiting transitory signs of anorexia and vomiting without laboratory evidence of organ pathology. Each subject received a once daily oral dose of KI (33 mg) that was found to be safe and effective in the prevention of radiation damage to the thyroid gland over the study period. With a moderate toxicity profile, Cotara may hold unique promise by delivering I‐131 directly into solid tumours of various types in felines.
Extragenital transmissible venereal tumour associated with circulating neoplastic cells in an immunologically compromised dog
Authors: Albanese F. , Salerni F. L. , Giordano S. , Marconato L. 
Published: March 2006

AbstractAn adult male intact boxer was presented because of diffuse cutaneous nodules. Fine‐needle aspirate revealed transmissible venereal tumour (TVT) cells. Neoplastic cells were also observed in the peripheral blood. Associated simultaneous diseases included leishmaniosis, demodicosis, papillomatosis and coccidiosis. Immunosuppression may have aggravated disease and triggered widespread metastases. The dog was hospitalized and administered oral amoxicillin/clavulanate, subcutaneous meglumine antimonite to treat leishmaniosis and oral chlortetracycline to treat coccidiosis. Intravenous injection of vincristine at weekly interval was used to treat TVT. A rapid regression of cutaneous nodules was noted; however, intractable diarrhoea developed, eventually leading to death after 18 days. This is the first report describing an unusual case of extragenital TVT associated with circulating neoplastic cells in an immunosuppressed dog presenting with multiple cutaneous nodules.
Surgical cytoreduction for the treatment of non‐lymphoid vertebral and spinal cord neoplasms in cats: retrospective evaluation of 26 cases (1990–2005)
Authors: Rossmeisl J. H. , Lanz O. I. , Waldron D. R. , Shires P. K. , Zimmerman K. L. , Sego L. H. 
Published: March 2006

AbstractMedical records of 26 cats with non‐lymphoid vertebral and spinal cord neoplasms treated surgically were reviewed to determine outcome and prognostic factors for survival. Of the factors examined, only tumour phenotype was significantly associated with survival. Osteosarcoma (3/26 cats) and meningioma (16/26 cats) were the most common malignant and benign tumours, respectively. The median survival time for cats with malignant neoplasms was 110.5 days, compared with 518 days for cats with benign tumours. Cytoreductive surgery resulted in clinical improvement in 25/26 cats, but local treatment failure occurred in 10/26 cats. Overall, 19/26 cats died of confirmed (12/19) or suspected (7/19) tumour‐related causes, including all eight cats with malignant neoplasms. Results suggest that contemporary neurosurgical techniques commonly result in incomplete excision of feline non‐lymphoid vertebral and spinal cord tumours but are efficacious at palliation of clinical signs of spinal cord dysfunction.
Active Pollination ofFicus surby Two Sympatric Fig Wasp Species in West Africa
Authors: Kerdelhué Carole , Hochberg Michael E. , Rasplus Jean‐Yves 
Published: March 2006

ABSTRACTCeratosolen silvestrianusandC. arabicusare two species of agaonine fig wasps that co‐occur in the figs ofFicus surin West Africa. Our work in the Ivory Coast shows that both are active pollinators, and that they may be found together in the same syconia. In our study area,C. silvestrianusis much more abundant thanC. flabellatus. We found no competitive effect for oviposition sites onC. silvestrianus, and hypothesize that habitat preferences allow the coexistence of two sympatric active pollinators in the sameFicushost in the Ivory Coast.RESUMENEn Afrique de I'Ouest, deux espéces d'hyménoptéres Agaoninae,Ceratosolen silvestrianusetC. flabellatus, sont associées àFicus surNotre étude en Côre d'Ivoire a montré que toutes dew pollinisent activement, et peuvent se développer ensemble au sein d'une même figue. Dans notre lieu de récolte,C. silvestrianusest bien plus abondant queC. fibellatus. Nous n'avons pas mis en évidence pourC. silvestrianus, de coût liéá la compétition avecC. flabellatus. La présence de deux pollinisateurs actifs sur un même site pourrait être due á I'existence d'une mosaïque d'habitats différents, abritant chacun préférentiellement une des deux espéces.
Asymbiotic Nitrogen Fixation and Litter Decomposition on a Long Soil‐Age Gradient in Hawaiian Montane Rain Forest1
Authors: Thompson Matthew V. , Vitousek Peter M. 
Published: March 2006

ABSTRACTWe determined rates of decomposition and asymbiotic nitrogen fixation in the leaf litter of Cheirodendron spp. on the Hawaiian Islands. Leaf litter was collected from four sites on a long soil‐age gradient (300 yr to 4.1 M yr) and decomposed at two sites that differed widely in substrate age and nutrient availability. Rates of decomposition were higher in litter decomposed at the older site, where nutrient availability was greater. A substantial amount of nitrogen and phosphorus immobilization occurred in litter decomposed at the older site, with more immobilization occurring in litter with lower initial nitrogen and phosphorus concentrations, suggesting both supply and demand controls on nutrient immobilization. Potential rates of nitrogen fixation were very low in the first 25 d (0–5 nmol acetylene/gdw/h), rose to much higher rates by 70 d (20–45 nmol), and then declined by 140 d. We found no significant difference in rates of potential nitrogen fixation between sites of decomposition, but there was a strong substrate effect, with higher rates in litter with low lignin, low nitrogen, and high phosphorus. Where significant immobilization of nitrogen occurred for decomposing Cheirodendron, nitrogen fixation could have comprised no more than 10 percent of immobilized nitrogen. Overall, rates of nitrogen fixation were dependent on the source of the decomposing substrate but not on the site of decomposition, while short‐term decomposition and nutrient immobilization were strongly dependent on the site of decomposition but not as much on the source of the decomposing substrate.
Correlating Stem Biomechanical Properties of Hawaiian Canopy Trees with Hurricane Wind Damage1
Authors: Asner Gregory P. , Goldstein Guillermo 
Published: March 2006

ABSTRACTHawaiian forests are subject to the effects of periodic hurricane conditions. Hurricane Iniki struck the island of Kauai, Hawaii on September 11, 1992 with winds exceeding 200 km/h and caused defoliation, felling of trees by snapping and uprooting, and standing tree mortality due excessive limb and leaf loss. The purpose of this study was to evaluate if measured wood mechanical characteristics could be correlated with stem failure of trees under windstorm conditions. A field survey indicated that post‐hurricane stem condition (snapped, uprooted, or standing) differed among five common canopy species and was significantly correlated with stem apparent elastic modulus (relative flexibility). Species that tended to snap had significantly higher apparent elastic moduli than those that remained standing or were uprooted. Wood density and stem diameter were not significantly related to stem failure mode. Native trees had a higher percentage per species of standing individuals but also had increased uprooting. Nonnative tree species were more often snapped and fewer were standing after the hurricane. The higher incidence of stem failure for introduced canopy trees may increase the spread of alien understory species following wind disturbance events. These relationships provide a simple means to predict relative differences in stem failure due to high wind conditions and should be considered in planning reforestation efforts on the Hawaiian Islands.
Dispersal of Spores of Mycorrhizal Fungi in Scats of Native Mammals in Tropical Forests of Northeastern Australia
Authors: Reddell Paul , Spain Alister V. , Hopkins Michael 
Published: March 2006

ABSTRACTOne hundred and thirty‐eight scat (faecal) samples from 17 mammal species native to forests of northeastern Queensland were examined for the presence of spores of both ectomycorrhizal and arbuscular mycorrhizal fungi. Spores of mycorrhizal fungi were found in 57 percent of scat samples representing 12 animal species (Aepyprymnus rufescens, Antechinus godmani, Bettongia tropica, Hypsiprymnodon moschatus, Isoodon macrourus, Melomys ceruinipes, Perameles nasuta, Rattus fuscipes, R. tunneyi, Thylogale stigmatica, Trichourur uulperula, Uromys caudimaculatus). Spores were absent in scats of Antechinus stuartii, Dasyurus hallucatus, Dendrolagus lumholtzi, Petaurus australis and Mesembriomys gouldii. Spores of ectomycorrhizal fungi occurred in 38 percent of scats, and all but one of these samples were from Eucalyptus‐dominated sclerophyll forests. Based on the frequency and abundance of spores in scats, five mammals were considered active consumers of hypogeous mycorrhizal sporocarps in sclerophyll forests (A. rufescens, B. tropica, I. macrourus, P. nasuta, and U. caudimaculatus). Individual scats of these animals generally contained a range of distinctive spore types. Spores of arbuscular mycorrhizal fungi were found in low abundance in almost 40 percent of scat samples collected, from both sclerophyll forest and rainforest habitats. We suggest that the majoriry of these spores were acquired incidentally through ingestion of soil during foraging activities on the forest floor. Glasshouse inoculation experiments in which seedlings of Eucalyptus grandis and Sorghum bicolor were inoculated with scat material from several species of mammal demonstrated that the spores of ectomycorrhizal and arbuscular mycorrhizal fungi retained some viability and colonized the roots of host‐plant seedlings. Insufficient information is known of the ecology of mycorrhizal fungi in Australia's tropical forests to speculate as to the implications of these findings for forest conservation and rehabilitation.
Structure and Dynamics of the Arboreal Termite Community in New Guinean Coconut Plantations21
Authors: Leponce Maurice , Roisin Yves , Pasteels Jacques M. 
Published: March 2006

ABSTRACTWhereas ant mosaics have been widely recognized and described in tropical ecosystems, data on space partitioning among arboreal termite colonies are rudimentary. During a long term field study in New Guinea, the distribution of arboreal termite species in coconut plantations as well as the extent and dynamics of competition between them were investigated. The three dominant species, Mirrocerotermes biroi, Nasutitermes princeps and N. novarumhebridarum, feed on the same items but never exploit the same tree. The resulting distribution pattern is a mosaic with two peculiarities. First, some extended areas around N. princeps colonies appear unexploited, as this species practices interference competition on a wide scale, defending large territories inter‐ and intra‐specifically. Second, interspecific relations are asymmetrical. In some plantations, large colonies of N. princeps expand their territory by destroying colonies of M. biroi, but when the pressure of N. princeps is relaxed, dense populations of colonies of M. biroi can recolonize the trees in a few years’ time. Territorial boundaries may thus change relatively fast. N. novarumhebridarum often colonizes dead trees and interferes less with the other species. These facts are consistent with each species’ reproductive investment strategy. Hypotheses are proposed to explain how the dominant species can coexist, even in long established plantations.
The Food Habits of Sympatric Jaguar and Puma in the Paraguayan Chaco
Authors: Taber Andrew B. , Novaro Andrés J. , Neris Nora , Colman Flavio H. 
Published: March 2006

ABSTRACTFood habits of jaguar and puma were studied in two regions of the Paraguayan Chaco. Biochemical analysis of 280 scats attributed 106 to jaguar and 95 to puma. Overall dietary overlap was 65 percent and they shared six of seven main prey types. For both cats 43 percent of prey items and 15 percent of prey biomass taken were mammal species kg, 23 percent of items and 29 percent of the biomass were from species 1–15 kg, and 27 percent of items and 53 percent of the biomass were from larger species. Birds, reptiles, and insects made up the remainder. In a developed region no significant differences between their diets were found, while in an undeveloped area more small mammals were taken by both species, and jaguar took more large prey than puma. The potential roles of competition and of differences in habitat structure and prey availability between the two areas on these species’ diets are discussed.RESUMENSe estudiaron los hábitos alimenticios de jaguar y puma en dos regiones del Chaco paraguayo. A través de un análisis bioquímico de 280 heces se asignaron 106 a jaguar y 95 a puma. La superposición trófica total fue 65 por ciento y compartieron 6 de 7 items presa principales. Para ambos gatos las especies de mamíferos de < 1 kg fueron el 43 por ciento de los items presa y el 15 por ciento de la biomasa de presas consumidas, 23 por ciento de items y 29 por ciento de la biomasa fueron de especies de 1–15 kg y 27 por ciento de items y 53 por ciento de biomasa heron de especies mayores. El resto heron aves, reptiles e insectos. En una región desarrollada no se encontraron diferencias significativas entre las dietas, mientras que en una región no desarrollada ambas especies consumieron más pequeños mamíferos y los jaguares consumieron más presas grandes que puma. Se discuten los posibles roles en la dieta de estas especies de la competencia y de diferencias en la estructura del hábitat, y la disponibilidad de presas entre las dos áreas.