Search results for "sterility"
showing 10 items of 21 documents
Homozygote Depression in Gamete-Derived Dragon-Fruit (Hylocereus) Lines
2018
Putative gamete-derived progenies from two Hylocereus species, the diploid H. monacanthus and the tetraploid H. megalanthus, were studied with the dual aims to confirm their gamete origin and to evaluate their potential use as genetic resources. An additional goal was to determine the origin (allotetraploid vs. autotetraploid) of H. megalanthus by exploring morphological variations in the di-haploid (2x) H. megalanthus progeny. Gamete origin was proved in all five H. monacanthus lines obtained and in 49 of the 70 H. megalanthus lines by using flow cytometry and simple sequence repeat (SSR) markers. The five double-haploid (2x) H. monacanthus lines showed low vigor and abnormal flower develo…
POSTMATING ISOLATION ANALYSIS IN FOUNDER-FLUSH EXPERIMENTAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA.
1996
In this paper, we report a detailed analysis intended to detect postmating barriers in experimental populations of Drosophila pseudoobscura obtained through nine founderflush cycles. The number of offspring produced was determined in three consecutive generations of hybridization. It is found that the evolution of premating barriers, as shown by two of these populations, is not necessarily accompanied by the evolution of postmating ones. Under the founder-flush model of speciation proposed by Carson (1971), the first step in the speciation process is usually thought to be an incidental genetic change through founder effect affecting mating behavior so that sexual premating isolation evolves…
The WtmsDW Locus on Wheat Chromosome 2B Controls Major Natural Variation for Floret Sterility Responses to Heat Stress at Booting Stage
2021
Heat stress at booting stage causes significant losses to floret fertility (grain set) and hence yield in wheat (Triticum aestivum L.); however, there is a lack of well-characterized sources of tolerance to this type of stress. Here, we describe the genetic analysis of booting stage heat tolerance in a cross between the Australian cultivars Drysdale (intolerant) and Waagan (tolerant), leading to the definition of a major-effect tolerance locus on the short arm of chromosome 2B, Wheat thermosensitive male sterile Drysdale/Waagan (WtmsDW). WtmsDW offsets between 44 and 65% of the losses in grain set due to heat, suggesting that it offers significant value for marker-assisted tolerance breedin…
Eradicating Mosquitoes using Translocations: a First Field Experiment
1972
THEORETICAL considerations have led to the assumption that chromosomal translocations with ensuing semisterility could be used to control pests1–3. Inversions could have the same effect in animals and plants in which crossing over occurs in both sexes4. Many translocations of different type and with various degrees of sterility have been produced in the mosquito Culex pipiens5–8. Preliminary laboratory experiments with these translocations have shown that a cage population can be diminished and finally exterminated after a few generations by the release of translocation heterozygotes into the population9.
Impact of polyploidy on fertility variation of Mediterranean Arundo L. (Poaceae)
2015
International audience; Failure of seed production in the genus Arundo L. (Poaceae) is often attributed to polyploidy. This study tested the impact of two ploidy levels (2n = 12 and 18x) on the fertility of four Mediterranean Arundo. Viable pollen was screened from its production to its germination, and seed occurrence was monitored in admixture or isolated conditions. In addition, insights on restructuration of polyploid genornes were analysed using molecular cytogenetics. Our results show that high ploidy levels do not automatically induce failure of sexual reproduction. The two ploidy levels are able to produce viable pollen and seed set depending on species and cultural conditions. The …
El valor de la Fisiocracia en su propio tiempo: un análisis crítico
2009
The value of the physiocratic doctrine is examined with an historical-analytical approach that takes into account both the French reality of the mid 18th century and the internal consideration of the doctrine. Starting from the overwhelming opposition of the French contemporaries, the three areas of the phyisiocrats’ system are critically reviewed: the philosophical-political framework, the theoretical economic analysis and the main maxims of the economic government. We conclude that Physiocracy, together with presenting some analytical advances, diagnosed the French economy inadequately, incurred in outstanding economic errors and proposed, within the political framework of severe “legal d…
Implementation and microbiological stability of dose-banded ganciclovir infusion bags prepared in series by a robotic system.
2018
Objectives The implementation of dose-banding (DB) in centralised, pharmacy-based cytotoxic drug preparation units allows the preparation of standardised doses in series. The aim of this study was to evaluate the feasibility of DB for the prescribing of ganciclovir (GV) infusion solutions and to investigate the microbiological stability of dose-banded, automatically prepared ready-to-administer GV infusion bags by media-fill simulation tests and sterility tests. Methods The frequency of prescription of GV doses was retrospectively analysed before and after implementing the DB scheme. Four dose-ranges or ‘bands’ and the corresponding standard doses (250, 300, 350, 400 mg) were identified. Th…
Postzygotic isolation between the two European subspecies of the house mouse: estimates from fertility patterns in wild and laboratory-bred hybrids
2005
We assessed the fertility (reproductive success, litter size, testis weight, spermatocyte-to-spermatid ratio) of F 1 s and backcrosses between different wild-derived outbred and inbred strains of two mouse subspecies, Mus musculus domesticus and M. m. musculus. A significant proportion of the F 1 females between the outbred crosses did not reproduce, suggesting that female infertility was present. As the spermatocyte-to-spermatid ratio was correlated with testis weight, the latter was used to attribute a sterile vs. fertile phenotype to all males. Segregation proportions in the backcrosses of F 1 females yielded 11 (inbred) to 17% (outbred) sterile males, suggesting the contribution of two …
Medikament�se Sterilit�t als T�uschungsmethode bei paternit�tsgutachten
1977
Bei der gerichtlichen Aufklarung einer strittigen Vaterschaft sind Tauschungen moglich. So kann eine medikamentos ausgeloste Infertilitat durch Eingriff an der Spermatogenese, am Spermientransport und an der hormonalen Steuerung herbeigefuhrt werden. Bis-Dichloracetyl-Octamethylendiamin ist aufgrund der spermiogenesehemmenden Wirkung besonders geeignet. Auser einem Antabus-Effekt bei gleichzeitiger Einnahme von Alkohol entstehen keine Nebenwirkungen. Bei der taglichen Einnahme von ca. 200 mg ist nach 2–3 Monaten eine Sterilitat ausgebildet. Nach Absetzen der Substanz ist die Spermatogenese und damit die Fertilitat des Mannes nach etwa 2 Monaten wieder vollig normal.
The sensitivity of buckwheat plants to pathogens under conditions of mixed viral and mycoplasmal infection
2016
It was investigated, that mixed infection of buckwheat distributed in various ecological regions of Ukraine, the pathogens that belong to different taxonomic groups have different and peculiar morphological and structural properties. First was shown that buckwheat is affected by buckwheat burn virus (BBV) together with Mycoplasma. Mixed infection leads to proliferation of sepals, clarification of the flowers petals, reduction and greening of petals, hypoplasia or hypodevelopment of stamens and pistils: all of this can lead to partial or complete sterility.