Search results for "ploidy"
showing 10 items of 299 documents
An ancestral recombination graph for diploid populations with skewed offspring distribution
2013
A large offspring number diploid biparental multilocus population model of Moran type is our object of study. At each timestep, a pair of diploid individuals drawn uniformly at random contribute offspring to the population. The number of offspring can be large relative to the total population size. Similar `heavily skewed' reproduction mechanisms have been considered by various authors recently. Each diploid parental individual contributes exactly one chromosome to each diploid offspring, and hence ancestral lineages can only coalesce when in distinct individuals. A separation of timescales phenomenon is thus observed. A result of M\"{o}hle (1998) is extended to obtain convergence of the an…
DNA content in nine species of Nematocera with special reference to the sibling species of the Anopheles maculipennis group and the Culex pipiens gro…
1972
DNA values were determined for the nine species: Telmatoscopus meridionalis (family Psychodidae), Dixa obscura (family Dixidae), and Culiseta litorea, Culex pipiens, Aedes caspius, Anopheles labranchiae, Anopheles atroparvus, Anopheles stephensi, and Anopheles freeborni (family Culicidae). The DNA content indicated that the species could be divided into three categories: The Culex group with Culex pipiens, Culiseta litorea and Aedes caspius containing 1.02, 0.92 and 0.99 pg DNA in the haploid set, the Anopheles group including the four Anopheles species A. labranchiae, A. atroparvus, A. stephensi, A. freeborni and Telmatoscopus meridionalis with 0.23, 0.24, 0.24, 0.29 and 0.24 pg DNA and th…
DNA aneuploidy and high proliferative activity but not K-ras-2 mutations as independent predictors of clinical outcome in operable gastric carcinoma:…
2001
BACKGROUND The prognostic value of DNA ploidy, S-phase fraction (SPF) and K-ras-2 mutations in gastric carcinoma (GC) has not yet been clearly defined. The aim of this study was to clarify the association between biomolecular variables, tumor characteristics, and clinical outcome in GC patients. METHODS Resected specimens from a consecutive series of 69 patients with GC who underwent potentially curative surgery were studied prospectively. DNA ploidy and SPF were assessed by flow cytometry on multiple frozen tumor samples, whereas K-ras-2 mutations were detected by polymerase chain reaction followed by single-strand conformation polymorphism. All the patients involved in this study were fol…
Morphometric and cytophotometric nuclear analysis of altered hepatocyte foci induced by N-nitrosomorpholine (NNM) and aflatoxin B1 (AFB1) in liver of…
1987
The progressive morphological changes in the liver during neoplastic transformation have been studied by histological, cytophotometric and morphometric methods in male Wistar rats treated with two carcinogens: N-nitrosomorpholine (NNM) and aflatoxin B1 (AFB1). Cytophotometric and morphometric analysis of hepatocyte nuclei using Feulgen-stained tissue sections were performed in morphologically normal hepatic parenchyma and in early preneoplastic foci composed of altered hepatocytes. Foci of clear cells, mixed cells and large basophilic cells possessed a ploidy distribution similar to the surrounding non-transformed parenchyma, while the small hyperbasophilic cell foci were predominantly dipl…
Prognosis in lower lip squamous cell carcinoma: assessment of tumor factors.
1998
We studied a consecutive series of 54 cases of lower lip squamous cell carcinoma (LLSCC) in order to identify any variables which might predict the development of lymph node metastases. The cases were divided into 38 tumors without metastases (group I) and 16 tumors with lymph node metastases (group II). The following factors were investigated: tumor size, histologic grading maximal thickness, perineural invasion, DNA ploidy and PCNA expression. In conclusion, we found that LLSCC greater than 2 cm in diameter, with histological grading G3-G4, thickness of more than 6 mm, DNA aneuploidy and high PCNA expression (PCNA LI > 0.48), were at high risk for the development of lymph node metastases.
Flow-cytometric DNA analysis of intracranial tumors in children.
2004
The objective of this study was to investigate flow-cytometric DNA values of pediatric intracranial tumors, and to establish DNA analysis as a potential prognostic parameter. Twenty-nine brain tumor specimens from 26 pediatric patients were cryo-preserved within a 3-year period. The DNA content was measured by flow cytometry. Six of the tumor specimens had aneuploid DNA patterns. The median of the proliferation index was lower in the survivor group compared with the non-survivor group (36.4% and 47.5%, respectively). Ten of the 26 patients are still alive, eight were lost to follow up, and eight died. Flow-cytometric DNA analysis may be a helpful tool for examining brain tumors in children.…
DNA-Ploidy, Morphometric-Stereological and P-Glycoprotein Study of Superficial Bladder Carcinomas
1992
We carried out a DNA-ploidy, morphometric-stereologic and P-glycoprotein study on 40 newly diagnosed superficial bladder cancer patients (G1-G2), correlating the results with histological grade and clinical outcome. Variations in the number of patients who present recurrences, progression or remain tumor-free during the whole follow-up period (at least 5 years) were not significant when related to nuclear size, proliferative diploid index, presence of aneuploidy and expression of P-glycoprotein. It is striking how the majority of disease-free subjects showed a proliferative diploid index higher than 10%. Moreover, 3 of them presented an aneuploid cell population. In our study, only histolog…
Growth charts of Down syndrome in Sicily: evaluation of 382 children 0-14 years of age.
2005
We present the results of a study performed on a Sicilian population of children with Down syndrome (DS) 0–14 years of age, observed between 1977 and 1988. Data from the present report concern 382 subjects with nonmosaic 21 trisomy, including 239 males (62.6%) and 143 females (37.4%). We excluded all DS children observed in the same period with associated pathology (congenital heart defects, gastrointestinal malformations, malabsorption, hypothyroidism, and thalassemia). Overall, 1,464 measurements were performed of length or height, weight, and head circumference. Means and standard deviation (SD) were calculated for all of these parameters. Our data confirm a trend toward a progressive im…
PSCDGs of mouse multipotent adult germline stem cells can enter and progress through meiosis to form haploid male germ cells in vitro
2010
Spermatogonial stem cells (SSCs) provide the basis for spermatogenesis throughout adult life by undergoing self-renewal and differentiation into sperm. SSC-derived cell lines called multipotent adult germline stem cells (maGSCs) were recently shown to be pluripotent and to have the same potential as embryonic stem cells (ESCs). In a differentiation protocol using retinoic acid (RA) and based on a double selection strategy, we have shown that ESCs are able to undergo meiosis and produce haploid male germ cells in vitro. Using this differentiation protocol we have now succeeded to generate haploid male germ cells from maGSCs in vitro. maGSCs derived from a Stra8-EGFP transgenic mouse line wer…
Does haplodiploidy purge inbreeding depression in rotifer populations?
2009
Background Inbreeding depression is an important evolutionary factor, particularly when new habitats are colonized by few individuals. Then, inbreeding depression by drift could favour the establishment of later immigrants because their hybrid offspring would enjoy higher fitness. Rotifers are the only major zooplanktonic group where information on inbreeding depression is still critically scarce, despite the fact that in cyclical parthenogenetic rotifers males are haploid and could purge deleterious recessive alleles, thereby decreasing inbreeding depression. Methodology/Principal Findings We studied the effects of inbreeding in two populations of the cyclical parthenogenetic rotifer Brach…