Adaptation to enemy shifts: rapid resistance evolution to local Vibrio spp. in invasive Pacific oysters

One hypothesis for the success of invasive species is reduced pathogen burden, resulting from a release from infections or high immunological fitness of invaders. Despite strong selection exerted on the host, the evolutionary response of invaders to newly acquired pathogens has rarely been considered. The two independent and genetically distinct invasions of the Pacific oyster Crassostrea gigas into the North Sea represent an ideal model system to study fast evolutionary responses of invasive populations. By exposing both invasion sources to ubiquitous and phylogenetically diverse pathogens (Vibrio spp.), we demonstrate that within a few generations hosts adapted to newly encountered pathogen communities. However, local adaptation only became apparent in selective environments, i.e. at elevated temperatures reflecting patterns of disease outbreaks in natural populations. Resistance against sympatric and allopatric Vibrio spp. strains was dominantly inherited in crosses between both invasion sources, resulting in an overall higher resistance of admixed individuals than pure lines. Therefore, we suggest that a simple genetic resistance mechanism of the host is matched to a common virulence mechanism shared by local Vibrio strains. This combination might have facilitated a fast evolutionary response that can explain another dimension of why invasive species can be so successful in newly invaded ranges

Estudos para definição de meios de cultura e métodos de desinfestação de explantes de plantas adultas de erva-mate (Ilex paraguarienses St. Hill).

Este trabalho é o resultado de uma série de estudos objetivando avaliar os efeitos de diferentes tratamentos (desinfestantes, antioxidantes, bactericidas, reguladores de crescimento e meios de cultura) na desinfestação e no controle da oxidação para o estabelecimento in vitro de explantes de erva-mate (Ilex paraguariensis), procedentes de árvores de 8 anos de idade, de Colombo - PR. A avaliação dos experimentos foi realizada sete dias após sua introdução in vitro, sendo verificadas grandes taxas gerais de contaminação por fungos e bactérias, bem como, a ocorrência de oxidação nos explantes. De forma geral, conclui-se que o hipoclorito de sódio a 1,5%, com tempo de imersão de 30 minutos e o etanol (álcool 70%) a dois minutos em explantes oriundos de brotações de mudas enxertadas foram os que proporcionaram os melhores resultados.Secão: Conservação, Melhoramento e Multiplicação. Feira do Agronegócio da Erva-mate, 1., 2003, Chapecó. Integrar para promover o agronegócio da erva-mate

The Effects of Prices and Policies on the Demand for Marijuana: Evidence from the National Household Surveys on Drug Abuse

Recent studies have shown that efforts to curb alcohol use by increasing the price of alcohol and limiting youth's access have succeeded, but they may have had the unintended consequencce of increasing marijuana use. This possibility is troubling in light of a recent government report that shows that marijuana use among teens more than doubled between 1990 and 1997. What impact will the proposed large increase in cigarette prices have on the demand for other substances such as marijuana? To better understand how the demand for marijuana responds to changes in the policies and prices that affect its use, we explore the National Household Survy on Drug Abuse (NHSDA). Overall, we find that marijuana, alcohol, and tobacco are complements, sot that increasing the price of any one will decrease the demand for marijuana. The results of this paper will help guide the creation of comprehensive policies that curb the use of marijuana in two ways: first, they quantify the effects of policies aimed at curbing the use of each substance, allowing policymakers to evaluate alternative policy options; and second, they clarify the dynamics and interactions between alcohol, tobacco, and marijuana use in response to government policies.

Produtividade anual em minijardim clonal de Araucaria angustifolia com diferentes soluções nutritivas.

Resumo

Influência de diferentes relações de reguladores de crescimento no alongamento in vitro de microestacas de Grevillea robusta (Cunn.)

Organizado por Patrícia Póvoa de Mattos, Celso Garcia Auer, Paulo César Botosso e Rejane Stumpf Sberze

Genetic parameters estimates and visual selection for leaves production in Ilex paraguariensis.

The selection of yerba mate superior genotypes, based on each plant leaf weight, is based on genetic parameters obtained from experimental plantations and it is practically impossible from the fourth year of age. Therefore, we estimate genetic parameters and check the feasibility of selection through notes and weight estimates of each tree at 18.5 years of age. The genetic material consists of a combined trial of provenances and progenies of half-sibs with 140 progenies from 7 provenances, installed in Ivaí, Paraná, Brazil, in a randomized block design with 10 repetitions. The genetic control of leaf production is of low magnitude (h2a = 0.175042 ± 0.0393) revealing high influence of the environment. The additive genetic correlations between the real weight of leaves × notes and real weight of leaves × visually estimated weight were of high magnitude (higher than 88%). Thus, the selection based on the leaves weight can be carried out without major losses in genetic gains by both methodologies when the purpose is the sexual selection, in which case the sort order has no importance. In the case of vegetative propagation, aiming clonal plantations, in which only the plants with the highest genotypic values should be selected, the selection by means of notes and leaves weight estimates proved to be inefficient

Persistence, seasonal dynamics and pathogenic potential of Vibrio communities from pacific oyster hemolymph

Bacteria of the genus Vibrio occur at a continuum from free-living to symbiotic life forms, including opportunists and pathogens, that can contribute to severe diseases, for instance summer mortality events of Pacific oysters Crassostrea gigas. While most studies focused on Vibrio isolated from moribund oysters during mortality outbreaks, investigations of the Vibrio community in healthy oysters are rare. Therefore, we characterized the persistence, diversity, seasonal dynamics, and pathogenicity of the Vibrio community isolated from healthy Pacific oysters. In a reciprocal transplant experiment we repeatedly sampled hemolymph from adult Pacific oysters to differentiate population from site-specific effects during six months of in situ incubation in the field. We characterized virulence phenotypes and genomic diversity based on multilocus sequence typing in a total of 70 Vibrio strains. Based on controlled infection experiments we could show that strains with the ability to colonize healthy adult oysters can also have the potential to induce high mortality rates on larvae. Diversity and abundance of Vibrio varied significantly over time with highest values during and after spawning season. Vibrio communities from transplanted and stationary oysters converged over time, indicating that communities were not population specific, but rather assemble from the surrounding environment forming communities, some of which can persist over longer period

Miniestaquia aplicada a espécies florestais.

A miniestaquia é uma técnica recente de propagação vegetativa cujo princípio é o aproveitamento do potencial juvenil dos propágulos para indução do enraizamento. Tendo em vista a necessidade de produção de mudas em larga escala para diversos fins, pode representar uma alternativa promissora para espécies lenhosas que manifestem dificuldade de enraizamento do material adulto ou cujas sementes representem fator limitante. Nesse sentido, este trabalho apresenta procedimentos e resultados de pesquisas desenvolvidas com gêneros amplamente utilizados na silvicultura clonal, como Eucalyptus e Pinus, além de outras espécies florestais com potencial para plantios comerciais e de recuperação de ecossistemas. Assim, buscou-se analisar as condições de implantação e manejo que contribuem para o desenvolvimento satisfatório das minicepas e miniestacas como incremento do processo. A introdução da miniestaquia apresenta vantagens relacionadas à redução da área de produção, diminuição do período de enraizamento e aclimatação, além da redução do uso de reguladores vegetais para indução do enraizamento

Resgate de indivíduos adultos selecionados de Eucalyptus viminalis por estaquia.

Resumo 19

Fitorreguladores de crescimento no alongamento in vitro de Pinus greggii.

Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso