Search results for " Reproduction"
showing 10 items of 282 documents
Anorectal malformations and pregnancy-related disorders: a registry-based case-control study in 17 European regions
2013
Objective To identify pregnancy-related risk factors for different manifestations of congenital anorectal malformations (ARMs).Design A population-based case-control study.Setting Seventeen EUROCAT (European Surveillance of Congenital Anomalies) registries, 1980-2008.Population The study population consisted of 1417 cases with ARM, including 648 cases of isolated ARM, 601 cases of ARM with additional congenital anomalies, and 168 cases of ARM-VACTERL (vertebral, anal, cardiac, tracheo-esophageal, renal, and limb defects), along with 13371 controls with recognised syndromes or chromosomal abnormalities.Methods Multiple logistic regression analyses were used to calculate adjusted odds ratios …
Review paper: Seasonal variation as a determinant of population structure in rotifers reproducing by cyclical parthenogenesis
1998
Monogonont rotifers live in habitats that display extensively variation in both biotic and abiotic components. Much of this variation is seasonal and therefore predictable for a given pond or lake. In 1972, King proposed one physiological and two genetic models presenting alternative modes of adaptation to this temporal variation. Our purpose in the present paper is to review and evaluate how our knowledge of the seasonal structure of rotifer populations has changed in the past 25 years. Seasonal changes in clone frequencies have been reported from three studies of natural populations using electrophoretic analysis of isozymes. In one of these studies there was evidence for substantial temp…
Predicting soil and plant water status dynamic in olive orchards under different irrigation systems with Hydrus-2D: Model performance and scenario an…
2018
The paper analyzes the performance of Hydrus-2D model to simulate the dynamic of soil water contents and transpiration fluxes in an olive orchard in which two different irrigation systems were used in 2011 and 2012. The relationship between measured midday stem water potential, MSWP, and simulated relative transpiration (ratio between simulated actual and maximum crop transpiration), Ks, was also identified with the aim to use the model for crop water status predictions. Finally, a scenario analysis was carried out for irrigation management purposes, by considering the level of crop water stress achieved in the different phases of the vegetative growth. The results evidenced that active roo…
Sister-chromatid exchange in cultured lymphocytes of ewes and their newborn lambs
1984
The incidence of sister-chromatid exchange (SCE) in cultured lymphocytes of ewes and their newborn lambs was determined using the BrdU-Giemsa technique. In all ewe-lamb pairs, the SCE rate in the lambs was less than that of the ewes. The mean SCE frequencies per chromosome of the ewes after lambing and of the newborn lambs were 0.1909 and 0.1581, respectively. The statistical analysis shows that a significant difference exists between SCE in the adult female sheep and their lambs. At the same time, a negative correlation was observed between SCE rate and cell proliferation. The results of this study are compared with those of previous reports on age-dependency of SCE.
Effects of tributyltin(IV) chloride on the gametes and fertilization ofAscidia malaca (Ascidiacea: Tunicata)
2003
Ascidia malaca gametes before fertilization incubated in 10-5 or 10-7 M solutions of tributyltin(IV) chloride, TBTCl, for 3 h appear highly damaged under transmission electron microscopy observation. Also, the fertilization process is affected by the compound: the damaged spermatozoa are present in the vitelline coat and the egg does not cleave. An increase of microbodies, structurally similar to peroxisomes, have been detected in the egg peripheral cytoplasm, probably in relation to their role in alleviating damage to some cellular components. The results have shown that the reproduction of ascidians under unfavourable environmental conditions is prevented. Copyright © 2003 John Wiley &…
Micropropagation of Globe Artichoke (Cynara cardunculus L. var. scolymus).
2013
The globe artichoke (Cynara cardunculus L. var. scolymus) is a perennial plant cultivated in the Mediterranean region and the Americas for its edible young flower heads. Although vegetative propagation by offshoots or by “ovoli” (underground dormant axillary buds) has been the primary method of propagation, the potential for the diffusion of diseases and the phenotypic variability can be very high. The propagation of this species by axillary shoot proliferation from in vitro cultured meristems produces systemic pathogen free plants and a higher multiplication rate as compared to that obtained by conventional agamic multiplication. Axillary shoot proliferation can be induced from excised sho…
Pythium segnitiumsp. nov., isolated from the Canary Islands â its taxonomy, ITS region of rDNA, and comparison with related species
2002
Pythium segnitium (CI-44) was isolated from some soil samples taken in the Canary Islands (Spain). This new species is a slow-growing fungus and is perfectly adapted to terrestrial habitat. It belongs to the group of Pythium that have smooth-walled oogonia, mostly hypogynous antheridia, and plerotic oospores. The fungus lacks sporangia, zoospores, and hyphal bodies are rarely formed. Thus the asexual reproduction, which is so common for fungi and especially for the aquatic ones, is completely lacking in this case. However the fungus reproduces sexually by the formation of oogonia, antheridia and oospores plentifully. The taxonomic description of this fungus, the nucleotide sequence of the i…
Pollen-pollen interactions in Betula pendula in vitro
1998
Direct pollen interactions, as well as interactions mediated by a recipient, can have a remarkable influence on pollen fertilization ability. Under conditions of pollen competition it could be advantageous if pollen grains interfered with the germination of other pollen. The aim of this study was to find out if there are direct negative or positive pollen–pollen interactions between pollen grains from genetically slightly different donors. The in vitro germinability of the pollen from several Betula pendula Roth clones was investigated. The pollen interactions between the clones were examined pairwise by using equal pollen mixtures. In three of the eight cases the germination percentage of …
Enemy recognition of Reed Warblers (Acrocephalus scirpaceus): threats and reproductive value act independently in nest defence modulation
2010
Organisms should respond more aggressively towards species perceived as a danger to their offspring, but intensity of defence may be gauged by the value of current offspring weighed against the value of future reproductive opportunities. We tested whether defensive responses of nesting reed warblers (Acrocephalus scirpaceus) are the result of an interaction effect between the type of stimulus confronted and the value of the warbler’s nesting attempt. We quantified the ability of reed warblers to discriminate among brood parasites, nestling predators and non-threatening species at different stages of the breeding cycle. We also determined whether variables that influence the value of offspri…
Vegetative and productive responses of ‘Conference’ and ‘Williams’ pear trees planted at different in-row spacings
2006
Abstract The effect of in-row spacing on the vegetative and productive performance of 4-year-old ‘Conference’ (CON) and ‘Williams’ (WIL) pear trees was studied. Analysis of digital images was used to estimate canopy growth and conformation. Fruit quality was determined by measuring fruit weight, flesh firmness, peel color, soluble solid content, and titratable acidity. WIL produced more and more efficiently than CON, especially at closer spacings. WIL canopies were generally bigger than CON canopies, and reduced spacing penalized stem growth and influenced canopy conformation. Root growth and conformation was similar for both cultivars, whereas decreasing in-row spacing reduced root dry wei…