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1.
Mol Ther ; 32(5): 1373-1386, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38504517

RESUMO

Epidemiological studies show that individuals who carry the relatively uncommon APOE ε2 allele rarely develop Alzheimer disease, and if they do, they have a later age of onset, milder clinical course, and less severe neuropathological findings than people without this allele. The contrast is especially stark when compared with the major genetic risk factor for Alzheimer disease, APOE ε4, which has an age of onset several decades earlier, a more aggressive clinical course and more severe neuropathological findings, especially in terms of the amount of amyloid deposition. Here, we demonstrate that brain exposure to APOE ε2 via a gene therapy approach, which bathes the entire cortical mantle in the gene product after transduction of the ependyma, reduces Aß plaque deposition, neurodegenerative synaptic loss, and, remarkably, reduces microglial activation in an APP/PS1 mouse model despite continued expression of human APOE ε4. This result suggests a promising protective effect of exogenous APOE ε2 and reveals a cell nonautonomous effect of the protein on microglial activation, which we show is similar to plaque-associated microglia in the brain of Alzheimer disease patients who inherit APOE ε2. These data increase the potential that an APOE ε2 therapeutic could be effective in Alzheimer disease, even in individuals born with the risky ε4 allele.


Assuntos
Doença de Alzheimer , Apolipoproteína E2 , Modelos Animais de Doenças , Terapia Genética , Camundongos Transgênicos , Microglia , Placa Amiloide , Animais , Doença de Alzheimer/terapia , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/etiologia , Camundongos , Terapia Genética/métodos , Humanos , Apolipoproteína E2/genética , Apolipoproteína E2/metabolismo , Placa Amiloide/metabolismo , Placa Amiloide/patologia , Microglia/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Doenças Neuroinflamatórias/etiologia , Doenças Neuroinflamatórias/terapia , Doenças Neuroinflamatórias/metabolismo , Peptídeos beta-Amiloides/metabolismo , Biomarcadores
2.
FASEB J ; 36(10): e22555, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36125010

RESUMO

Although α-synuclein (SNCA) is a well-known pathological molecule involved in synucleinopathy in neurons, its physiological roles remain largely unknown. We reported that serum SNCA levels have a close inverse correlation with blood pressure and age, which indicates the involvement of SNCA in age-related endothelial dysfunction. Therefore, this study aimed to elucidate the molecular functions of SNCA in the endothelium. We confirmed that SNCA was expressed in and secreted from endothelial cells (ECs). Exogenous treatment with recombinant SNCA (rSNCA) activated the Akt-eNOS axis and increased nitric oxide production in ECs. Treatment with rSNCA also suppressed TNF-α- and palmitic acid-induced NF-κB activation, leading to the suppression of VCAM-1 upregulation and restoration of eNOS downregulation in ECs. As for endogenous SNCA expression, replicative senescence resulted in the attenuation of SNCA expression in cultured ECs, similar to the effects of physiological aging on mice aortas. The siRNA-mediated silencing of SNCA consistently resulted in senescent phenotypes, such as eNOS downregulation, increased ß-gal activity, decreased Sirt1 expression, and increased p53 expression, in ECs. Ex vivo assessment of endothelial functions using aortic rings revealed impaired endothelium-dependent acetylcholine-induced relaxation in SNCA knockout (KO) mice. Furthermore, SNCA KO mice, especially those on a high-fat diet, displayed elevated blood pressure compared with wild-type mice; this could be eNOS dysfunction-dependent because of the lower difference caused by L-NAME administration. These results indicate that exogenous and endogenous SNCA in ECs might physiologically maintain vascular integrity, and age-related endothelial dysfunction might be partially ascribed to loss-of-function of SNCA in ECs.


Assuntos
Doenças Vasculares , alfa-Sinucleína/metabolismo , Acetilcolina/metabolismo , Animais , Células Endoteliais/metabolismo , Camundongos , Camundongos Knockout , NF-kappa B/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/metabolismo , Ácido Palmítico/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/metabolismo , Sirtuína 1/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Molécula 1 de Adesão de Célula Vascular/metabolismo , Doenças Vasculares/metabolismo
3.
Dement Geriatr Cogn Disord ; 52(2): 108-116, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36878194

RESUMO

INTRODUCTION: A rapidly increasing number of patients with dementia present a serious social problem. Recently, the incidence of epilepsy in patients with Alzheimer's disease (AD) is increasing, drawing attention to the pathological relationship between the two conditions. Clinical studies have suggested the protective action of antiepileptic agents on dementia; however, the underlying mechanism remains unknown. We evaluated the effects of multiple antiepileptic drugs using tau aggregation assay systems to determine the effects of antiepileptic agents on tau aggregation, a major neuropathological finding associated with AD. METHODS: We evaluated the effects of seven antiepileptic agents on intracellular tau aggregation using a tau-biosensor cell-based high-throughput assay. Next, we tested these agents in a cell-free tau aggregation assay using thioflavin T (ThT). RESULTS: The assay results revealed that phenobarbital inhibited tau aggregation, whereas sodium valproate, gabapentin, and piracetam promoted tau aggregation. In the cell-free tau aggregation assay using ThT, we confirmed that phenobarbital significantly inhibited tau aggregation. CONCLUSION: Antiepileptic drugs may modify the tau pathology in AD in a neural activity-independent manner. Our finding may provide an important insight into the optimization of antiepileptic drug therapy in older adults with dementia.


Assuntos
Doença de Alzheimer , Anticonvulsivantes , Humanos , Idoso , Anticonvulsivantes/farmacologia , Anticonvulsivantes/uso terapêutico , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/patologia , Proteínas tau , Ácido Valproico/farmacologia , Ácido Valproico/uso terapêutico , Fenobarbital/uso terapêutico
4.
FASEB J ; 35(3): e21419, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33566370

RESUMO

In the early phase of the Coronavirus disease 2019 (COVID-19) pandemic, it was postulated that the renin-angiotensin-system inhibitors (RASi) increase the infection risk. This was primarily based on numerous reports, which stated that the RASi could increase the organ Angiotensin-converting enzyme 2 (ACE2), the receptor of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in rodents. RASi can theoretically antagonize the potential influence of angiotensin II (Ang II) on ACE2. However, while Ang II decreases the ACE2 levels in cultured cells, there is little evidence that supports this phenomenon in living animals. In this study, we tested whether Ang II or Ang II combined with its antagonist would alter the ACE2 and other molecules associated with the infection of SARS-CoV-2. Male C57BL6/J mice were administered vehicle, Ang II (400 ng/kg/min), or Ang II with losartan (10 mg/kg/min) for 2 weeks. ACE2 knockout mice were used as a negative control for the ACE2 assay. We found that both Ang II, which elevated blood pressure by 30 mm Hg, and Ang II with losartan, had no effect on the expression or protein activity of ACE2 in the lung, left ventricle, kidney, and ileum. Likewise, these interventions had no effect on the expression of Transmembrane Protease Serine 2 (TMPRSS2) and Furin, proteases that facilitate the virus-cell fusion, and the expression or activity of Tumor Necrosis Factor α-Convertase (TACE) that cleaves cell-surface ACE2. Collectively, physiological concentrations of Ang II do not modulate the molecules associated with SARS-CoV-2 infection. These results support the recent observational studies suggesting that the use of RASi is not a risk factor for COVID-19.


Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Angiotensina II/farmacologia , Enzima de Conversão de Angiotensina 2/metabolismo , COVID-19/metabolismo , Losartan/farmacologia , SARS-CoV-2 , Proteína ADAM17/genética , Proteína ADAM17/metabolismo , Angiotensina II/administração & dosagem , Bloqueadores do Receptor Tipo 1 de Angiotensina II/administração & dosagem , Enzima de Conversão de Angiotensina 2/genética , Animais , Furina/genética , Furina/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Losartan/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Vasoconstritores/farmacologia
5.
AJNR Am J Neuroradiol ; 45(3): 320-327, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38331963

RESUMO

BACKGROUND AND PURPOSE: Biomarkers have been required for diagnosing early Alzheimer disease. We assessed the utility of hippocampal diffusion parameters for diagnosing Alzheimer disease pathology in mild cognitive impairment. MATERIALS AND METHODS: Sixty-nine patients with mild cognitive impairment underwent both CSF measurement and multi-shell diffusion imaging at 3T. Based on the CSF biomarker level, patients were classified according to the presence (Alzheimer disease group, n = 35) or absence (non-Alzheimer disease group, n = 34) of Alzheimer disease pathology. Neurite orientation dispersion and density imaging and diffusion tensor imaging parametric maps were generated. Two observers independently created the hippocampal region of interest for calculating histogram features. Interobserver correlations were calculated. The statistical significance of intergroup differences was tested by using the Mann-Whitney U test. Logistic regression analyses, using both the clinical scale and the image data, were used to predict intergroup differences, after which group discriminations were performed. RESULTS: Most intraclass correlation coefficient values were between 0.59 and 0.91. In the regions of interest of both observers, there were statistically significant intergroup differences for the left-side neurite orientation dispersion and density imaging-derived intracellular volume fraction, right-side diffusion tensor imaging-derived mean diffusivity, left-side diffusion tensor imaging-derived mean diffusivity, axial diffusivity, and radial diffusivity (P < .05). Logistic regression models revealed that diffusion parameters contributed the most to discriminating between the groups. The areas under the receiver operating characteristic curve for the regions of interest of observers A/B were 0.69/0.68, 0.69/0.68, 0.73/0.68, 0.71/0.68, and 0.68/0.68 for the left-side intracellular volume fraction (mean), right-side mean diffusivity (mean), left-side mean diffusivity (10th percentile), axial diffusivity (10th percentile), and radial diffusivity (mean). CONCLUSIONS: Hippocampal diffusion parameters might be useful for the early diagnosis of Alzheimer disease.


Assuntos
Doença de Alzheimer , Humanos , Doença de Alzheimer/patologia , Imagem de Tensor de Difusão/métodos , Imagem de Difusão por Ressonância Magnética/métodos , Hipocampo/diagnóstico por imagem , Hipocampo/patologia , Biomarcadores
6.
bioRxiv ; 2023 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-37645718

RESUMO

Epidemiological studies show that individuals who carry the relatively uncommon APOE ε2 allele rarely develop Alzheimer disease, and if they do they have a later age of onset, milder clinical course, and less severe neuropathological findings than others with Alzheimer disease. The contrast is especially stark in comparison to the phenotype associated with the major genetic risk factor for Alzheimer disease, APOE ε4, which has an age of onset several decades earlier, as well as a more aggressive clinical course and notably more severe neuropathological findings, especially in terms of the amount of amyloid deposition. Even one APOE ε2 allele improves phenotype, but it is uncertain if that is due to the replacement of a more toxic allele by APOE ε2, or if APOE ε2 has a protective, neuro-modulatory effect. Here, we demonstrate that brain exposure to APOE2 via a gene therapy approach which bathes the entire cortical mantle in the gene product after transduction of the ependyma, rapidly ameliorates established Aß plaque deposition, neurodegenerative synaptic loss, and, remarkably, reduces microglial activation in an APP/PS1 mouse model despite continued expression of human APOE4. This result suggests a promising protective effect of exogenous APOE2, revealing a cell non-autonomous effect of the protein on microglial activation. We also show that plaque associated microglia in the brain of patients who inherit APOE2 similarly have less microglial reactivity to plaques. These data raise the potential that an APOE2 therapeutic could be effective in Alzheimer disease even in individuals born with the risk ε4 allele. One Sentence Summary: Introduction of ApoE2 using an AAV that transduces the ependymal cells of the ventricle causes a reduction in amyloid load and plaque associated synapse loss, and reduces neuroinflammation by modulating microglial responsiveness to plaques.

7.
Sci Adv ; 9(47): eadg3193, 2023 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-37992159

RESUMO

Repulsive guidance molecule A (RGMa) was originally identified as a neuronal growth cone-collapsing factor. Previous reports have demonstrated the multifunctional roles of RGMa mediated by neogenin1. However, the pathogenic involvement of RGMa in amyotrophic lateral sclerosis (ALS) remains unclear. Here, we demonstrated that RGMa concentration was elevated in the cerebrospinal fluid of both patients with ALS and transgenic mice overexpressing the mutant human superoxide dismutase1 (mSOD1 mice). Treatment with humanized anti-RGMa monoclonal antibody ameliorated the clinical symptoms in mSOD1 mice. Histochemical analysis revealed that the anti-RGMa antibody significantly decreased mutant SOD1 protein accumulation in the motor neurons of mSOD1 mice via inhibition of actin depolymerization. In vitro analysis revealed that the anti-RGMa antibody inhibited the cellular uptake of the mutant SOD1 protein, presumably by reinforcing the neuronal actin barrier. Collectively, these data suggest that RGMa leads to the collapse of the neuronal actin barrier and promotes aberrant protein deposition, resulting in exacerbation of the ALS pathology.


Assuntos
Esclerose Lateral Amiotrófica , Animais , Humanos , Camundongos , Actinas , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Anticorpos , Camundongos Transgênicos , Neurônios Motores/metabolismo , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1/genética
8.
Fluids Barriers CNS ; 19(1): 31, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35505336

RESUMO

BACKGROUND: Cerebrospinal fluid (CSF) provides a close representation of pathophysiological changes occurring in the central nervous system (CNS); therefore, it has been employed in pathogenesis research and biomarker development for CNS disorders. CSF obtained from valid mouse models relevant to CNS disorders can be an important resource for successful biomarker and drug development. However, the limited volume of CSF that can be collected from tiny intrathecal spaces and the technical difficulties involved in CSF sampling has been a bottleneck that has hindered the detailed analysis of CSF in mouse models. METHODS: We developed a novel chronic dural port (CDP) method without cannulation for CSF collection of mice. This method enables easy and repeated access to the intrathecal space in a free-moving, unanesthetized mouse, thereby enabling continuous long-term CSF collection with minimal tissue damage and providing a large volume of high-quality CSF from a single mouse. When combined with chemical biosensors, the CDP method allows for real-time monitoring of the dynamic changes in neurochemicals in the CSF at a one-second temporal resolution in free-moving mice. Moreover, the CDP can serve as a direct access point for the intrathecal injection of CSF tracers and drugs. RESULTS: We established a CDP implantation and continuous CSF collection protocol. The CSF collected using CDP was not contaminated with blood and maintained physiological concentrations of basic electrolytes and proteins. The CDP method did not affect mouse's physiological behavior or induce tissue damage, thereby enabling a stable CSF collection for up to four weeks. The spatio-temporal distribution of CSF tracers delivered using CDP revealed that CSF metabolism in different brain areas is dynamic. The direct intrathecal delivery of centrally acting drugs using CDP enabled real-time behavioral assessments in free-moving mice. CONCLUSIONS: The CDP method enables the collection of a large volume of high-quality CSF and direct intrathecal drug administration with real-time behavioral assessment in free-moving mice. Combined with animal models relevant to CNS disorders, this method provides a unique and valuable platform for biomarker and therapeutic drug research.


Assuntos
Doenças do Sistema Nervoso Central , Sistemas de Liberação de Medicamentos , Animais , Camundongos , Biomarcadores/líquido cefalorraquidiano , Doenças do Sistema Nervoso Central/líquido cefalorraquidiano , Modelos Animais de Doenças , Injeções Espinhais , Preparações Farmacêuticas
9.
Nat Ecol Evol ; 3(10): 1415-1418, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31527727

RESUMO

Despite the growing importance of farmed fish for contemporary economies, the origins of aquaculture are poorly known. Although it is widely assumed that fish domestication began much later than the domestication of land animals, the evidence is largely negative. Here, we use age-mortality and species-selection profiles of fish bones from prehistoric East Asia to show that managed aquaculture of common carp (Cyprinus carpio) was present at the Early Neolithic Jiahu site, Henan Province, China, by around 6000 BC.


Assuntos
Carpas , Animais , Aquicultura , China , Ásia Oriental , Alimentos Marinhos
10.
Nat Ecol Evol ; 3(10): 1494, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31551524

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

11.
Sci Rep ; 9(1): 12932, 2019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31506486

RESUMO

A rapid increase in the number of patients with dementia has emerged as a global health challenge. Accumulating evidence suggests that early diagnosis and timely intervention can delay cognitive decline. The diagnosis of dementia is commonly performed using neuropsychological tests, such as the Mini-Mental State Examination (MMSE), administered by trained examiners. While these traditional neuropsychological tests are valid and reliable, they are neither simple nor sufficiently short as routine screening tools for dementia. Here, we developed a brief cognitive assessment utilizing an eye-tracking technology. The subject views a series of short (178 s) task movies and pictures displayed on a monitor while their gaze points are recorded by the eye-tracking device, and the cognitive scores are determined from the gaze plots data. The cognitive scores were measured by both an eye tracking-based assessment and neuropsychological tests in 80 participants, including 27 cognitively healthy controls (HC), 26 patients with mild cognitive impairment (MCI), and 27 patients with dementia. The eye tracking-based cognitive scores correlated well with the scores from the neuropsychological tests, and they showed a good diagnostic performance in detecting patients with MCI and dementia. Rapid cognitive assessment using eye-tracking technology can enable quantitative scoring and the sensitive detection of cognitive impairment.


Assuntos
Disfunção Cognitiva/diagnóstico , Demência/diagnóstico , Movimentos Oculares/fisiologia , Programas de Rastreamento/métodos , Desempenho Psicomotor , Idoso , Estudos de Casos e Controles , Diagnóstico Precoce , Feminino , Humanos , Masculino
12.
Rinsho Shinkeigaku ; 58(3): 171-177, 2018 Mar 28.
Artigo em Japonês | MEDLINE | ID: mdl-29491330

RESUMO

We report a forty-six-year-old man with a past history of brain abscess managed by surgical drainage and recurrent ischemic strokes. After treatment of brain abscess, he had been on medication for symptomatic epilepsy, but had ceased medication by his judgment. He was taken to a hospital in an ambulance for an epileptic seizure. In the hospital he suffered from drug-induced renal dysfunction caused by the intravenous anti-epileptic drug, and right hemiparesis due to ischemic stroke occurred on the third hospitalization day. He was transferred to our hospital to get a treatment for renal failure. His renal function improved gradually by hemodialysis, but an ischemic stroke recurred in the right cerebellar hemisphere. Closer examinations on the mechanisms of his strokes revealed the draining of right superior vena cava (RSVC) directly into the left atrium (LA), persistent left superior vena cava (PLSVC) and atrial septal defect (ASD). He had a rare anomaly of the systemic venous return. It seemed that his repeated strokes were caused by paradoxical embolism through the draining of RSVC to LA, and air or thrombi in the infusion lines other than intravenous thrombi was thought to be an embolic cause in this case.


Assuntos
Embolia Paradoxal/complicações , Comunicação Interatrial/complicações , Acidente Vascular Cerebral/etiologia , Veia Cava Superior/anormalidades , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva , Acidente Vascular Cerebral/diagnóstico por imagem
13.
Clin Calcium ; 15(2): 286-8, 2005 Feb.
Artigo em Japonês | MEDLINE | ID: mdl-15692171

RESUMO

A group of fish is not a mophyletic and includes some different classification groups. Fish are the popular name of animals which has the shape of fish. Most of fish bear jaw, but some fish do not have jaws. Formation of jaw is an important event in the history of early vertebrates. Jaws are originated from visceral arches. Mandibular and hyal arches play a role of jaw apparatus. The jaw of most fish are supported by hyomandibular which are upper part of hyoid arch. Fish obtained various jaw structure and mechanism.


Assuntos
Peixes/anatomia & histologia , Arcada Osseodentária/anatomia & histologia , Animais , Evolução Biológica
14.
Clin Calcium ; 15(3): 184-6, 2005 Mar.
Artigo em Japonês | MEDLINE | ID: mdl-15741701

RESUMO

Structure of Jaws in fish composed of mandibular and hyoid arches. Hyomandibular which is upper part of hyoid arch plays an important role of jaw suspension. Various jaw structures are developed in fish. One of the samples is protrusible upper jaw in cyprinid fish. Development of the protrusible jaw structure was related to degeneration of oral teeth and development of pharyngeal teeth in cyprinids.


Assuntos
Peixes/anatomia & histologia , Arcada Osseodentária/anatomia & histologia , Animais , Cyprinidae/anatomia & histologia
15.
Sci China C Life Sci ; 47(2): 130-8, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15379245

RESUMO

Complete mitochondrial cytochrome b sequences of 54 species, including 18 newly sequenced, were analyzed to infer the phylogenetic relationships within the family Cyprinidae in East Asia. Phylogenetic trees were generated using various tree-building methods, including Neighbor-joining (NJ), Maximum Parsimony (MP) and Maximum Likelihood (ML) methods, with Myxocyprinus asiaticus (family Catostomidae) as the designated outgroup. The results from NJ and ML methods were mostly similar, supporting some existing subfamilies within Cyprinidae as monophyletic, such as Cultrinae, Xenocyprinae and Gobioninae (including Gobiobotinae). However, genera within the subfamily "Danioninae" did not form a monophyletic group. The subfamily Leuciscinae was divided into two unrelated groups: the "Leuciscinae" in East Asia forming as a monophyletic group together with Cultrinae and Xenocyprinae, while the Leucisciriae in Europe, Siberia, and North America as another monophyletic group. The monophyly of subfamily Cyprininae sensu Howes was supported by NJ and ML trees and is basal in the tree. The position of Acheilognathinae, a widely accepted monophyletic group represented by Rhodeus sericeus, was not resolved.


Assuntos
Cyprinidae/classificação , Cyprinidae/genética , Citocromos b/genética , Filogenia , Sequência de Aminoácidos , Animais , Geografia , Alinhamento de Sequência
16.
J Morphol ; 272(4): 503-12, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21290421

RESUMO

Homologies of the branchial arch muscles in the cyprinid Zacco platypus are assessed based on their innervation. Muscles serving the first gill arch are innervated by branches of the glossopharyngeal (IX) nerve and those serving other arches by the vagal (X) nerve. Absence of the levator posterior is confirmed. Five pairs of muscles originating from the cranium and inserted onto the specialized 5th ceratobranchial, all unique to cyprinids, are innervated by the 4th branchial trunks of X, indicating that all pairs are derivatives of the sphincter oesophagi, involving reorganization from intrinsic to extrinsic elements. Homologies of some ventral branchial muscles are also discussed and the criteria for homology improved by clarifying the innervation pattern.


Assuntos
Região Branquial/anatomia & histologia , Região Branquial/inervação , Cyprinidae/anatomia & histologia , Músculos/anatomia & histologia , Músculos/inervação , Animais , Cyprinidae/embriologia , Brânquias/anatomia & histologia
17.
J Morphol ; 205(2): 155-163, 1990 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29865742

RESUMO

The appearance pattern of pharyngeal tooth germs was investigated in the larval Japanese dace, Tribolodon hakonensis, which has a bilaterally asymmetrical dentition. Teeth develop in a series of replacement waves beginning with the initial central tooth (Ce) and continuing with teeth of anterior (An) and posterior (Po) positions relative to the initial one. Identified by wave number (n) and tooth position (r), according to the formula n-1 [r], tooth germs appeared in the order of tooth 0 [Ce0], 1 [Po1], 1 [Anl], 2 [Ce0], 2 [An2], 3 [Po1], 3 [An1], 4 [Ce0], 4[An2], 5 [Po1], 5 [An1], 5 [An3], 6 [Ce0], 6 [An2] during the larval period. Dentition on the right side, however, lacks the first tooth at position An2 (tooth 2 [An2]) and teeth at position An3. Tooth germs on the first, second, and third replacement waves appeared simultaneously on the arches of both sides. During following waves, tooth germs on the left side appeared later than those on the right. Delay of tooth germ appearance On the left side is interpreted as an inhibitory influence of existing tooth germs in accordance with Osborn's (Proc. R. Soc. Lond. Ser. B 179:261--289, '71) theory. The delay of tooth germ appearance on the left arch is most pronounced on the seventh replacement wave. Teeth of the right major row in adults of this species are replaced more frequently than those of the left major row, apparently in correlation with the absence of the first larval tooth at position An2 and teeth at position An3. It is hypothesized that cyprinids evolved the minor rows and specialized teeth of their adult dentition as apomorphic characteristics by the process of neoteny.

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