Disrupted Maturation of Prefrontal Layer 5 Neuronal Circuits in an Alzheimer's Mouse Model of Amyloid Deposition / 神经科学通报·英文版

Mutations in genes encoding amyloid precursor protein (APP) and presenilins (PSs) cause familial forms of Alzheimer's disease (AD), a neurodegenerative disorder strongly associated with aging. It is currently unknown whether and how AD risks affect early brain development, and to what extent subtle synaptic pathology may occur prior to overt hallmark AD pathology. Transgenic mutant APP/PS1 over-expression mouse lines are key tools for studying the molecular mechanisms of AD pathogenesis. Among these lines, the 5XFAD mice rapidly develop key features of AD pathology and have proven utility in studying amyloid plaque formation and amyloid β (Aβ)-induced neurodegeneration. We reasoned that transgenic mutant APP/PS1 over-expression in 5XFAD mice may lead to neurodevelopmental defects in early cortical neurons, and performed detailed synaptic physiological characterization of layer 5 (L5) neurons from the prefrontal cortex (PFC) of 5XFAD and wild-type littermate controls. L5 PFC neurons from 5XFAD mice show early APP/Aβ immunolabeling. Whole-cell patch-clamp recording at an early post-weaning age (P22-30) revealed functional impairments; although 5XFAD PFC-L5 neurons exhibited similar membrane properties, they were intrinsically less excitable. In addition, these neurons received smaller amplitude and frequency of miniature excitatory synaptic inputs. These functional disturbances were further corroborated by decreased dendritic spine density and spine head volumes that indicated impaired synapse maturation. Slice biotinylation followed by Western blot analysis of PFC-L5 tissue revealed that 5XFAD mice showed reduced synaptic AMPA receptor subunit GluA1 and decreased synaptic NMDA receptor subunit GluN2A. Consistent with this, patch-clamp recording of the evoked L23>L5 synaptic responses revealed a reduced AMPA/NMDA receptor current ratio, and an increased level of AMPAR-lacking silent synapses. These results suggest that transgenic mutant forms of APP/PS1 overexpression in 5XFAD mice leads to early developmental defects of cortical circuits, which could contribute to the age-dependent synaptic pathology and neurodegeneration later in life.

Arbuscular mycorrhizae in Paris polyphylla var. yunnanensis / 中国中药杂志

<p><b>OBJECTIVE</b>To study the infection situation of arbuscular mycorrhizal fungi, as well as the mycorrhizal structures of Paris polyphylla var. yunnanensis, and the main types and quantities of AMF spores in rhizosphere soil.</p><p><b>METHOD</b>The arbuscular mycorrhizal of P. polyphylla var. yunnanensis were detected by Phillips and Hayman staining. At the same time, some AMF spores were accessed by Gendemann's Wet-screening method and identified by their morphological characteristics.</p><p><b>RESULT</b>Arbuscular mycorrhizal fungi could infect the roots of P. polyphylla var. yunnanensis and formed arbuscular mycorrhizal. Infection rate was from 35.3% to 98.6%, indicating that infection strength was strong. From 10 soil samples collected in Yunnan, 11 Acaulospor species, 7 Glomus species, 3 Gigaspora species and 3 Scutellospora species were isolated and identified, including Acaulospora appendicola, A. brieticulata, A. excavata, A. foveata, A. lacunosa, A. laevis, A. koskei, A. myriocarpa, A. polonica, A. rehmii, A. scrobiculata, Glomus albidum, G. ambisporum, G. deserticola, G. fragarioides, G. luteum, G. microaggregatum, G. multiforum, Gigaspora albida, G. margarita, G. ramisporophora, Scutellospora calospora, S. pellucida and S. gilmorei. Among them, Acaulospora brieticulata was advantage species.</p><p><b>CONCLUSION</b>AMF may be a potent biological resource which can stimulate the growth of P. polyphylla var. yunnanensis.</p>