A comparison of methods for the evaluation of the physiological quality of soybean seeds with emphasis to the use of the electrical conductivity test.

Sementes de três cultivares de soja foram submetidas a testes de germinação, tetrazólio, frio, envelhecimento artificial, condutividade elétrica e emergência das plântulas em campo, nas instalações do Departamento de Agricultura da ESALQ/USP, entre os meses de outubro de 1987 e abril de 1988. Avaliaram-se diferentes períodos de embebição pré-leitura da condutividade elétrica, com o objetivo principal de verificar a possibilidade da redução da duração desse teste. Concluiu-se que a avaliação do potencial fisiológico das sementes em laboratório deve ser baseada no conjunto dos resultados de diferentes testes. Dentre eles, períodos mais curtos de embebição (4 e 8 horas) pré-leitura da condutividade podem ser utilizados para identificação de diferenças mais acentuadas de vigor, enquanto a embebição durante 16 ou 20 horas toma esse teste mais sensível às diferenças do vigor de sementes de sojaAn experiment was set at the Agriculture Dept., ESALQ/USP, Piracicaba, Brasil, between October/ 1987 and April 1988 with the purpose of comparing the efficiency of diferent tests in evaluating the physiological quality of seeds from three soybean (Glycine max (L.) Merrill) cultivars. The comparisons included the germination, tetrazolium, cold, accelerated aging, electrical conductivity and field emergence tests. Different imbibition periods for the electrical conductivity test were also compared. It was concluded that the physiological quality of soybean seeds is best estimated when based upon results from several different tests. Among them, the shorter imbibition periods (4 and 8 hours) for the bulk conductivity test can be used for the detection of wide vigor differences, while a 16 or 20 hours imbibition period can be used for identifying smaller differences among soybean seed lots

TSPAN5 Enriched Microdomains Provide a Platform for Dendritic Spine Maturation through Neuroligin-1 Clustering

Tetraspanins are a class of evolutionarily conserved transmembrane proteins with 33 members identified in mammals that have the ability to organize specific membrane domains, named tetraspanin-enriched microdomains (TEMs). Despite the relative abundance of different tetraspanins in the CNS, few studies have explored their role at synapses. Here, we investigate the function of TSPAN5, a member of the tetraspanin superfamily for which mRNA transcripts are found at high levels in the mouse brain. We demonstrate that TSPAN5 is localized in dendritic spines of pyramidal excitatory neurons and that TSPAN5 knockdown induces a dramatic decrease in spine number because of defects in the spine maturation process. Moreover, we show that TSPAN5 interacts with the postsynaptic adhesion molecule neuroligin-1, promoting its correct surface clustering. We propose that membrane compartmentalization by tetraspanins represents an additional mechanism for regulating excitatory synapses

Assessment of genetic parameters of degradability in maize grains due to indentation scores

Maize (Zea mays L.) cultivars with dent grains present higher starch and dry matter ruminal degradability than those with flint grains. This study aimed to assess genetic parameters of degradability in maize grains of different textures and to verify whether there is an association between grain indentation score and ruminal dry matter (RDM) degradability. The evaluated progenies were obtained from the cross between the varieties Cristal (flint) and Cunha (dent), previously selected for grain hardness. Progenies were evaluated for an indentation score using a visual grading scale ranging from 1 (flint) to 5 (dent). To assess the RDM degradability, 5 g were cut into halves, weighed (five grams), stored in bags made of 100% "failet" cloth and incubated for 24 h in the rumen of three ruminally cannulated cows. There was genetic variability for RDM degradability and heritability was 46%, indicating the possibility of success using a selection. There was no association between indentation score and RDM degradability percentage; thus, visual evaluation not always reflects grain hardness per se since it indicates the pericarp aspect but not the endosperm constitution.Cultivares de milho (Zea mays L.) com grãos do tipo dentado possuem maior porcentagem de amido e degradabilidade ruminal da matéria seca do que os com grãos do tipo duro. Estimaram-se parâmetros genéticos da degradabilidade de grãos de milho com diferentes texturas e verificou-se se ocorre associação entre o escore de identação dos grãos visualmente avaliados e a degradabilidade in situ da matéria seca (DISMS). Foram avaliadas progênies oriundas do cruzamento entre a variedade Cristal, de grãos duros, e a variedade Cunha de grãos dentados, previamente selecionadas para a dureza dos grãos. As progênies foram avaliadas com relação ao escore de identação por meio de uma escala visual de notas variando de 1 (duro) a 5 (mole). Para a avaliação da DISMS os grãos foram cortados ao meio, pesados 5 g colocados em saquinhos de tecido "failet" e incubados no rúmen, por 24 h, em três vacas portadoras de cânula ruminal. Há variabilidade genética para a DISMS, com herdabilidade de 46%, indicando ser possível o sucesso com a seleção. Não há associação entre o escore de identação e a porcentagem de DISMS. Assim, a avaliação visual nem sempre reflete a dureza per se dos grãos, pois o que se vê é o aspecto do pericarpo e não a constituição do endosperma

Generalization of the Menegozzi and Lamb maser algorithm to the transient superradiance regime

We investigate the application of the conventional quasi-steady state maser modelling algorithm of Menegozzi & Lamb (ML) to the high field transient regime of the one-dimensional Maxwell-Bloch (MB) equations for a velocity distribution of atoms or molecules. We quantify the performance of a first order perturbation approximation available within the ML framework when modelling regions of increasing electric field strength, and we show that the ML algorithm is unable to accurately describe the key transient features of R. H. Dicke\u27s superradiance (SR). We extend the existing approximation to one of variable fidelity, and we derive a generalization of the ML algorithm convergent in the transient SR regime by performing an integration on the MB equations prior to their Fourier representation. We obtain a manifestly unique integral Fourier representation of the MB equations which is $\mathcal {O}\left(N\right)$ complex in the number of velocity channels N and which is capable of simulating transient SR processes at varying degrees of fidelity. As a proof of operation, we demonstrate our algorithm\u27s accuracy against reference time domain simulations of the MB equations for transient SR responses to the sudden inversion of a sample possessing a velocity distribution of moderate width. We investigate the performance of our algorithm at varying degrees of approximation fidelity, and we prescribe fidelity requirements for future work simulating SR processes across wider velocity distributions