Search results for "Reproduction"

Can the Caper (Capparis spinosa L.) Still Be Considered a Difficult-to-Propagate Crop?

2021

As a perennial xerophytic shrub, characterized by plesiomorphic features, the caper (Capparis spinosa L.) is naturally spread throughout the Mediterranean basin and occupies an important ecological role, as well as an economic one, in traditional and specialized systems for commercial production. This species, in spite of its wide diffusion, is currently considered at risk of genetic erosion, mainly due to overgrazing and overharvesting for domestic uses and for trade. This situation is made more serious because of the lack of efficient propagation techniques, determining the caper as a “difficult-to-propagate species”. In this review, we report the main available sexual and vegetative prop…

Seasonal gene expression kinetics between diapause phases in Drosophila virilis group species and overwintering differences between diapausing and no…

2015

AbstractMost northern insect species experience a period of developmental arrest, diapause, which enables them to survive over the winter and postpone reproduction until favorable conditions. We studied the timing of reproductive diapause and its long-term effects on the cold tolerance of Drosophila montana, D. littoralis and D. ezoana females in seasonally varying environmental conditions. At the same time we traced expression levels of 219 genes in D. montana using a custom-made microarray. We show that the seasonal switch to reproductive diapause occurs over a short time period and that overwintering in reproductive diapause has long-lasting effects on cold tolerance. Some genes, such as…

Effects of the Shiitake Mushroom on Ontogenesis and Reproduction of the Social Vole Microtus socialis

2001

Social phenotype extended to communities: expanded multilevel social selection analysis reveals fitness consequences of interspecific interactions.

2014

In social species, fitness consequences are associated with both individual and social phenotypes. Social selection analysis has quantified the contribution of conspecific social traits to individual fitness. There has been no attempt, however, to apply a social selection approach to quantify the fitness implications of heterospecific social phenotypes. Here, we propose a novel social selection based approach integrating the role of all social interactions at the community level. We extended multilevel selection analysis by including a term accounting for the group phenotype of heterospecifics. We analyzed nest activity as a model social trait common to two species, the lesser kestrel (Falc…

Sex- and age-related variation in survival and cost of first reproduction in Greater Flamingos

2001

International audience; We analyzed survival of breeding Greater Flamingos, Phoenicopterus ruber roseus, using the capture histories of 2000 breeding birds ringed as chicks and resighted at their natal colony in the Camargue, southern France. As found in previous analyses, recapture probability varied according to year, sex, and age of the bird, and annual survival was strongly affected by winter severity. However, by using a much larger data set than in earlier analyses, we detected previously nonsignificant effects. Indeed, for the first time, sex and age of the bird were found to influence annual survival probability. We tested the hypothesis that the observed sex-related difference in s…

Progress in the characterization of insulin-like peptides in aphids: Immunohistochemical mapping of ILP4.

2021

Aphids were the first animals described as photoperiodic due to their seasonal switch from viviparous parthenogenesis to sexual reproduction (cyclical parthenogenesis) caused by the shortening of the photoperiod in autumn. This switch produces a single sexual generation of oviparous females and males that mate and lay diapausing cold-resistant eggs that can overcome the unfavourable environmental conditions typical of winter in temperate regions. Previous studies have hinted at a possible implication of two insulin-like peptides (ILP1 and ILP4) in the aphid seasonal response, changing their expression levels between different photoperiodic conditions. Moreover, in situ localization of their…

Improved Mesophyll Protoplast Culture and Plant Regeneration in Arabidopsis thaliana (L.) Heynh., Genotype Landsberg Erecta

1993

Summary The response of in vitro cultured Arabidopsis thaliana mesophyll protoplasts was investigated with the aim of characterising the crucial factors that affect plating efficiencies and plant regeneration. We selected the genotype Landsberg erecta, which is frequently used for genetic studies, but which is known to respond poorly in protoplast culture. Factors permitting vigorous vegetative growth of the donor plants, i.e. short light period and avoidance of high temperature, were found to be advantageous. Selection of competent leaves and fractionation of protoplast populations indicated that predominantly protoplasts derived from still expanding, yet not highly immature mesophyll cell…

Cadmium effects on development and reproduction of Oncopeltus fasciatus (Heteroptera: Lygaeidae)

2004

Newly hatched nymphs of the insect Oncopeltus fasciatus were exposed to various concentrations of CdCl2 administered in drinking water until the end of adult life. Significant nymphal mortalities were observed at concentrations above 30 mg Cd/l (corresponding to the LC50). The duration of the nymphal stages increased in proportion to the Cd concentration; at the lowest Cd concentration of 10 mg Cd/l, the median duration was significantly prolonged by one day, while at the highest concentration of 100 mg Cd/l it was increased by 10 days over the control group. The weight of newly emerged adults lineally decreased with Cd concentration, being reduced to half the weight of controls at 100 mg C…

Effects of arbuscular mycorrhizal fungi and maternal plant sex on seed germination and early plant establishment.

2015

Premise of the study: Arbuscular mycorrhizal fungi usually enhance overall plant performance, yet their effects on seed germi- nation and early plant establishment, crucial steps in plant cycles, are generally overlooked. In gynodioecious species, sexual dimorphism in these traits has been reported, with females producing seeds that germinate at a faster rate than seeds from hermaphrodites. • Methods: Using the gynodioecious plant Geranium sylvaticum, I investigated in a greenhouse experiment whether the presence of arbuscular mycorrhizal spores affects seed germination and early plant establishment, examining at the same time whether the sex of the mother producing the seeds also influence…

Social capital and the networked public sphere: Implications for political social media sites

2012

Submitted version of a paper from the 45th Hawaii International Conference on System Science (HICSS), 2012. Published version available from IEEE: http://dx.doi.org/10.1109/hicss.2012.535 This paper presents a theoretical lens for research on social media use in eParticipation, along with an example case study. The idea of the public sphere and how it can be applied to eParticipation research is presented. The public sphere is discussed in relation to Castell's notion of the network society as the "networked public sphere", and social capital is introduced as a possible explanation for why some people choose to participate while others refrain from doing so. An example case is presented and…