PINP: a new method of tagging neuronal populations for identification during in vivo electrophysiological recording

Neural circuits are exquisitely organized, consisting of many different neuronal subpopulations. However, it is difficult to assess the functional roles of these subpopulations using conventional extracellular recording techniques because these techniques do not easily distinguish spikes from different neuronal populations. To overcome this limitation, we have developed PINP (Photostimulation-assisted Identification of Neuronal Populations), a method of tagging neuronal populations for identification during in vivo electrophysiological recording. The method is based on expressing the light-activated channel channelrhodopsin-2 (ChR2) to restricted neuronal subpopulations. ChR2-tagged neurons can be detected electrophysiologically in vivo since illumination of these neurons with a brief flash of blue light triggers a short latency reliable action potential. We demonstrate the feasibility of this technique by expressing ChR2 in distinct populations of cortical neurons using two different strategies. First, we labeled a subpopulation of cortical neurons-mainly fast-spiking interneurons-by using adeno-associated virus (AAV) to deliver ChR2 in a transgenic mouse line in which the expression of Cre recombinase was driven by the parvalbumin promoter. Second, we labeled subpopulations of excitatory neurons in the rat auditory cortex with ChR2 based on projection target by using herpes simplex virus 1 (HSV1), which is efficiently taken up by axons and transported retrogradely; we find that this latter population responds to acoustic stimulation differently from unlabeled neurons. Tagging neurons is a novel application of ChR2, used in this case to monitor activity instead of manipulating it. PINP can be readily extended to other populations of genetically identifiable neurons, and will provide a useful method for probing the functional role of different neuronal populations in vivo

Classical and quantum dynamics of confined test particles in brane gravity

A model is constructed for the confinement of test particles moving on a brane. Within the classical framework of this theory, confining a test particle to the brane eliminates the effects of extra dimensions, rendering them undetectable. However, in the quantized version of the theory, the effects of the gauge fields and extrinsic curvature are pronounced and this might provide a hint for detecting them. As a consequence of confinement the mass of the test particle is shown to be quantized. The condition of stability against small perturbations along extra dimensions is also studied and its relation to dark matter is discussed.Comment: 15 pages, no figures, extended, references adde

Comportamento de Panicum maximum cv. Tanzânia sob diferentes graus de estresse híbrico.

A água é um dos principais fatores limitantes ao desenvolvrmento de plantas forrageiras em pastagens. O objetivo desse trabalho foi avaliar a resposta do capim-tanzânia ao estresse hídrico. O experimento foi conduzido em casa-de-vegetação na Embrapa Pecuária Sudeste. Foram avaliados três níveis de disponibilidade de água (100, 60 e 30% do total de água disponível do solo) e três períodos de estresse (5, 10 e 15 dias) em uma delineamento em blocos completos ao acaso com arranjo fato ria! e três repetições. O capim-tanzânia apresenta mecanismos de adaptação ao estresse hídrico moderado em curtos períodos de tempo, reduzindo principalmente o desenvolvimento de folhas. A cultura sofre redução acentuada da massa seca quando submetida a estresse hídrico severo e prolongado. Durante a fase de implantação em áreas irrigadas, a reposição de água deve ocorrer quando a umidade do solo atingir 60% do armazenamento total

Utilização da gema de ovo de diferentes espécies e proporções sobre a conservação do sêmen congelado de ovinos da raça.

Resumo: Objetivou-se verificar a utilização da gema de ovo de diferentes espécies e sua taxa de adição (10% e 20%) sobre as características de motilidade do sêmen congelado de carneiro. Foram coletados cinco ejaculados de três carneiros da raça Santa Inês, uma vez por semana. Após a coleta foi feito um pool do ejaculado e avaliado o volume, motilidade, vigor e concentração espermática. O pool foi fracionado em quatro alíquotas para testar diferentes tratamentos: Tris (10% e 20% de gema de ovo de galinha caipira) e Tris (10% e 20% de gema de ovo de codorna). As amostras foram envasadas em palhetas de 0,25 ml e congeladas na temperatura de -79º C em equipamento TK 3000. Após 30 dias, foram descongeladas, e o sêmen avaliado pelo método CASA. Os dados foram analisados pela ANOVA e as médias foram comparadas pelo teste de tukey (5% de probabilidade). A porcentagem de espermatozóides móveis foi significativamente melhor no Tris com 10% de gema de ovo de galinha. As variáveis, motilidade progressiva e motilidade de espermatozóides rápidos apresentaram as melhores taxas no Tris com 10% de gema de ovo de galinha, mas não diferiram do Tris com 10% de gema de ovo de codorna. A VAPR foi superior no Tris com 20% de gema de ovo de galinha. Neste estudo, a porcentagem de gema de ovo de ambas as espécies foi que melhor preservou os parâmetros de motilidade espermática. A gema de ovo de codorna poderá ser uma alternativa, no entanto, mais estudos in vivo são necessários para avaliar sua eficiência como um aditivo ao diluidor Tris. Abstract: This study aimed to verify the influence of eggs yolk types (chicken and quail) and addition rates (10% and 20%) on the motility parameters of ram frozen semen. Five ejaculated of the three Santa Inês rams were colleted once a week. After collection a pool of the ejaculates was made and evaluated for volume, motility, vigor and sperm concentration. Fractioned in four aliquotas for the test of treatment different: Tris (10% and 20% of egg yolk of hens) and Tris (10% and 20% of egg yolk of quail). The samples were potted in straws of 0,25 mL and frozen at a temperature of -79º C in the equipment TK 3000. After 30 days, were thawed and evaluated the semen by CASA methodt. Data were anlyzed by ANOVA and means compared by Tukey test ( 5% of probability). The percentage of mobiles spermatozoa was significantly better in Tris with 10% of egg yolk of chicken. The variables progressive motility and rapid motility of spermatozoa showed the best rates in Tris with 10% of chicken egg yolk, but didn't differ in Tris with 10% off egg yolk of quail. The VAPR was superior in Tris with 20% of egg yolk of chicken. In this study, the percentage of 10% off egg yolk in the both species was best preserved in the parameters of sperm motility. The egg yolk of quail may be an alternative; however, further studies "in vivo" are necessary to evaluate its efficiency as an additive for Tris extender

Uso de plantas barreiras na redução da transmissão do Cowpea Aphid-Borne Mosaic Vírus (CABMV) por Aphis craccivora.

Autoria: QUERINO [i.e. SILVA], R. B. Q. da. RANYSE BARBOSA QUERINO DA SILV

Unified dark energy thermodynamics: varying w and the -1-crossing

We investigate, in a unified and general way, the thermodynamic properties of dark energy with an arbitrary, varying equation-of-state parameter w(a). We find that all quantities are well defined and regular for every w(a), including at the -1-crossing, with the temperature being negative in the phantom regime (w(a)-1). The density and entropy are always positive while the chemical potential can be arbitrary. At the -1-crossing, both temperature and chemical potential are zero. The temperature negativity can only be interpreted in the quantum framework. The regular behavior of all quantities at the -1-crossing, leads to the conclusion that such a crossing does not correspond to a phase transition, but rather to a smooth cross-over.Comment: 5 pages, version published in Class. Quant. Gra