T-Type Ca2+ Channels Mediate a Critical Period of Plasticity in Adult-Born Granule Cells.

Adult-born granule cells (abGCs) exhibit a transient period of elevated synaptic plasticity that plays an important role in hippocampal function. Various mechanisms have been implicated in this critical period for enhanced plasticity, including minimal GABAergic inhibition and high intrinsic excitability conferred by T-type Ca2+ channels. Here we assess the contribution of synaptic inhibition and intrinsic excitability to long-term potentiation (LTP) in abGCs of adult male and female mice using perforated patch recordings. We show that the timing of critical period plasticity is unaffected by intact GABAergic inhibition such that 4-6-week-old abGCs exhibit LTP that is absent by 8 weeks. Blocking GABAA receptors, or partial blockade of GABA release from PV and nNos-expressing interneurons by a µ-opioid receptor agonist, strongly enhances LTP in 4-week-old GCs, suggesting that minimal inhibition does not underlie critical period plasticity. Instead, the closure of the critical period coincides with a reduction in the contribution of T-type Ca2+ channels to intrinsic excitability, and a selective T-type Ca2+ channel antagonist prevents LTP in 4-week-old but not mature GCs. Interestingly, whole-cell recordings that facilitate T-type Ca2+ channel activity in mature GCs unmasks LTP (with inhibition intact) that is also sensitive to a T-type Ca2+ channel antagonist, suggesting T-type channel activity in mature GCs is suppressed by native intracellular signaling. Together these results show that abGCs use T-type Ca2+ channels to overcome inhibition, providing new insight into how high intrinsic excitability provides young abGCs a competitive advantage for experience-dependent synaptic plasticity.

Dinâmica da população de coliformes durante a compostagem automatizada de dejetos líquidos de suínos / Population dynamics during composting of fecal automated pig slurry

Microrganismos presentes em dejetos de suínos podem contaminar o meio ambiente. Embora a compostagem seja preconizada como um método eficiente para reduzir este potencial poluidor dos dejetos, existem poucas informações de pesquisa sobre tal processo. O presente trabalho teve o objetivo de avaliar a eficiência da compostagem automatizada dos dejetos líquidos de suínos (DLS) na redução da população de coliformes, usados como indicadores de poluição fecal. Os DLS foram adicionados periodicamente, durante 106 dias, em substrato constituído pela mistura, em partes iguais, de maravalha e serragem. Foram efetuadas 14 adições de DLS, e em cada adição as leiras de compostagem eram revolvidas por meio de uma máquina especialmente desenvolvida para este fim. Foram avaliados dois tratamentos com três repetições, sendo um com e outro sem adição de ácido fosfórico aos dejetos, até pH 6,0. A adição de ácido visou reduzir as perdas de N por volatilização de amônia (NH3) durante a compostagem. A avaliação da população de coliformes foi feita pela técnica do número mais provável (NMP), com uso do caldo Fluorocult, incubado a 37ºC por 24h e posterior leitura em luz ultravioleta. A população de coliformes fecais não foi afetada pela adição de ácido fosfórico. O processo de compostagem automatizada foi eficiente na redução de coliformes fecais, cuja população original passou de 4,2x1010 para 1,2 x 105 ao final da compostagem (156 dias) sem adição de ácido e de 3,8x1010 para 2,3x104 na compostagem com adição de ácido. Essa remoção de coliformes fecais, promovida pela compostagem automatizada dos dejetos líquidos de suínos, corresponde a 99,99 por cento...

Microorganisms present in pig manure can contaminate the environment. Although composting is recommended as an efficient method to reduce the pollution potential of waste, there is little research information on this process. This study aimed to evaluate the efficiency of automated composting of pig slurry (PS) in reducing the population of coliforms, used as fecal pollution indicators. The PS was added periodically during 106 days in substrate, with a mixture, in equal parts, of wood shavings and sawdust. There were 14 additions of PS and at each addition the compost windrows were revolved through a machine especially developed for this purpose. Two treatments with three replications were evaluated, one with and one without the addition of phosphoric acid to the slurry up to pH 6.0. The acid addition aimed to reduce N losses through the volatilization of ammonia (NH3) during composting. Coliforms were evaluated by the technique of most probable number (MPN) using the Fluorocult broth, incubated at 37 ° C for 24 h and subsequent reading in ultra violet light. The population of fecal coliforms was not affected by the addition of phosphoric acid. The automated composting process was effective in reducing faecal coliforms, whose original population decreased from 4.2 x 1010 to 1.2 x 105 at the end of composting (156 days) without addition of acid and from 3.8 x1010 to 2,3 x104 in compost with added acid. This removal of faecal coliforms, promoted by automated composting of pig slurry, corresponds to 99.99 percent...