Evolution. Traversing the adaptive landscape in snapdragons.
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Adaptation, Biological↗
Biomedical subjects
Kathleen Donohue
Publications and source records attributed to Kathleen Donohue.
Role of prophylactic hysterectomy in patients at high risk for hereditary cancers.
BACKGROUND: Current surgical recommendations for ovarian cancer prophylaxis in women at high risk of developing ovarian cancer include bilateral salpingo-oophorectomy (risk-reducing salpingo-oophorectomy (RRSO)). The role of hysterectomy is unclear. We sought to determine outcomes following prophylactic surgery in high-risk women. METHODS: We surveyed unaffected members of the Gilda Radner Familial Ovarian Cancer Registry who had undergone oophorectomy from 1981 to 2002. Data were collected and analyzed for statistical significance by the Fisher's Exact Test. RESULTS: Two hundred eighty women were surveyed, and 154 (55%) responded; 97% were Caucasian and 14% reported being Jewish. The median age of the respondents was 51 years (range 29-79); median age at oophorectomy was 41 years (range 15-68). Fifty-eight patients (38%) reported a laparoscopic procedure. One hundred five patients (68%) had a simultaneous hysterectomy, and 4 (3%) had a prior hysterectomy. Forty-four patients (29%) underwent BSO only. Of these 44 patients, 40 (91%) did not require a subsequent hysterectomy. Of the 4 who did, 2 were for leiomyomas, one for menorrhagia and the other was unknown. While not statistically significant, of the 3 patients who developed a subsequent gynecologic malignancy, all had undergone a hysterectomy. There was a statistically significant difference in whether or not the uterus was removed as part of the procedure by time period, whereby women treated prior to 1990 had a higher likelihood of having a hysterectomy (P = 0.03). CONCLUSION: The women in our study did not require hysterectomy for prevention of malignancy. We conclude that one should screen for benign gynecological indications for hysterectomy when planning a prophylactic BSO for prevention of ovarian cancer. Other potential risk factors for endometrial cancer, including the role of UPSC in HBOC, remain to be elucidated.
Adult↗
A quantitative exploration of surface antigen expression in common B-cell malignancies using flow cytometry.
The use of flow cytometry to diagnose hematological malignancies has become routine due to its ability to often differentiate between morphologically similar diseases based on antigens expressed on the surface of malignant cells. In an attempt to expand on the utility of flow cytometry in the study of B-cell malignancies we have used the most reliable quantitative methodology, QIFI (quantitative indirect immunofluorescence assay), to study the expression of CD5, CD10, CD11c, CD19, CD20, CD22, CD23, and CD79b in 384 cases of several common B-lineage malignancies, including: B-ALL, CLL, SLL, hairy cell leukemia, diffuse large B-cell lymphoma, and follicular lymphoma. The impetus behind this extensive, single institution study of surface antigens was two-fold: evaluating similarities and differences of antigen expression between B-cell neoplasms and finding additional clinical utility for the quantitative flow cytometric data generated. Our results show that each distinct malignant histology has its own quantitative pattern of surface antigen expression. In most cases, these quantitative patterns do not increase the ability of flow cytometry to distinguish between them. However, a high expression of specific antigens on a given B-cell malignancy may potentially identify optimal therapeutic targets for current and/or future monoclonal antibody-based therapies.
Antigens, Differentiation, B-Lymphocyte↗
Results of a phase 1 clinical trial of thalidomide in combination with fludarabine as initial therapy for patients with treatment-requiring chronic lymphocytic leukemia (CLL).
Tumor necrosis factor alpha (TNF-alpha) and vascular endothelial growth factor (VEGF) play an important role in the biology of chronic lymphocytic leukemia (CLL) cells. Thalidomide is a first-generation immuno-modulating agent that down-regulates TNF-alpha and VEGF. We initiated a phase 1/2 clinical trial to determine the safety and efficacy of combining thalidomide with fludarabine in patients with treatment-naïve CLL. Patients received 6 months of continuous daily thalidomide with standard monthly doses of fludarabine. Three dose levels of thalidomide (100, 200, and 300 mg) were studied. Results from the phase 1 part of this study are reported here. Thirteen patients were enrolled in the phase 1 component of the study. Dose-limiting toxicity was not reached. The most common toxicities noted were fatigue, constipation, and peripheral sensory neuropathy. Overall response rate was 100% with 55% of patients achieving complete remissions. At a median follow-up of 15+ months none of the patients have had a relapse and the median time to disease progression has not yet been reached. Responses were noted at all dose levels. Thalidomide given up to 300 mg/day concurrently with fludarabine in patients with previously untreated CLL shows encouraging clinical efficacy and acceptable toxicity. An ongoing phase 2 part of this study will help validate the clinical efficacy of this regimen.
Antineoplastic Agents↗
Genetic basis and consequences of niche construction: plasticity-induced genetic constraints on the evolution of seed dispersal in Arabidopsis thaliana.
Because seed dispersal influences the environment experienced by seeds, that environment can change as dispersal evolves. The evolutionary potential of dispersal can in turn change as dispersal evolves, if its expression of genetic variation depends on the postdispersal environment. We examined whether seed dispersion patterns have a detectable genetic basis (and therefore evolutionary potential) and determined whether that genetic basis changed depending on one postdispersal environmental factor: conspecific density. We grew replicates of 12 ecotypes of Arabidopsis thaliana at high and low density and measured seed dispersion patterns and maternal traits associated with dispersal under controlled conditions. We found density-dependent ecotypic variation for maternal traits that influence dispersal. Significant genetic variation for postdispersal sibling density was detected only when plants were grown at high density, suggesting that if dispersal evolves to result in lower postdispersal densities, the expression of genetic variation for dispersal would be reduced. This dynamic could lead to a plasticity-induced constraint on the evolution of dispersal. The ability of organisms to alter the environment they experience and the ability of that environment to evolve can alter evolutionary dynamics by augmenting or reducing evolutionary potential and thereby facilitating or constraining evolutionary responses to selection.
Arabidopsis↗
Niche construction through phenological plasticity: life history dynamics and ecological consequences.
The ability of an organism to alter the environment that it experiences has been termed 'niche construction'. Plants have several ways whereby they can determine the environment to which they are exposed at different life stages. This paper discusses three of these: plasticity in dispersal, flowering timing and germination timing. It reviews pathways through which niche construction alters evolutionary and ecological trajectories by altering the selective environment to which organisms are exposed, the phenotypic expression of plastic characters, and the expression of genetic variation. It provides examples whereby niche construction creates positive or negative feedbacks between phenotypes and environments, which in turn cause novel evolutionary constraints and novel life-history expression.
Biological Evolution↗
Expression of intestinal trefoil factor (TFF-3) in hepatocellular carcinoma.
BACKGROUND: Trefoil peptides (TFF-1, 2, 3) are a family of protease-resistant regulatory factors that play a role in mucosal restitution, angiogenesis, apoptosis, and tumor progression. Intestinal trefoil peptide (TFF-3) expression has been demonstrated in benign hepatobiliary diseases, but there are limited data regarding its expression in HCC. METHODS: Thirty consecutive cases of HCC from 1998 to 2003 were studied. Immunohistochemistry was performed on formalin-fixed paraffin-embedded blocks of HCC using polyclonal antibody to TFF-3. TFF-3 expression was classified as strong, moderate, weak, focal, and negative. Clinical data were obtained per an IRB-approved protocol. RESULTS: Median age was 69 yr (range: 39-83 yr). Twenty- three patients were males and 7 were females. Treatments included hepatic resection (n = 16), chemo-embolization (n = 4), combined modality therapy (n = 5) and no treatment (n = 4). HCC was well differentiated in 12 (40%), moderately differentiated in 13 (43%), and poorly differentiated in 5 (17%) patients. TFF-3 expression was detected in 28/30 (93.3%) patient samples. Sixteen patients (53%) had moderate and 1 (3%) patient had strong TFF-3 expression. Tumor/ normal tissue interface was assessable in 21 cases; 11 cases expressed TFF-3 at the interface. There was a strong correlation between tumor grade and TFF-3 expression, wherein poorly differentiated tumors had moderate/strong TFF-3 expression (p = 0.008). There was no correlation between TFF-3 expression and survival (p = 0.77). Furthermore, there was no correlation among age, disease stage, and survival. CONCLUSION: TFF-3 is commonly expressed in HCC and its expression correlates with tumor grade.
Adult↗
Environmental and genetic influences on the germination of Arabidopsis thaliana in the field.
Seasonal germination timing strongly influences lifetime fitness and can affect the ability of plant populations to colonize and persist in new environments. To quantify the influence of seasonal environmental factors on germination and to test whether pleiotropy or close linkage are significant constraints on the evolution of germination in different seasonal conditions, we dispersed novel recombinant genotypes of Arabidopsis thaliana into two geographic locations. To decouple the photoperiod during seed maturation from the postdispersal season that maternal photoperiod predicts, replicates of recombinant inbred lines were grown under short days and long days under controlled conditions, and their seeds were dispersed during June in Kentucky (KY) and during June and November in Rhode Island (RI). We found that postdispersal seasonal conditions influenced germination more strongly than did the photoperiod during seed maturation. Genetic variation was detected for germination responses to all environmental factors. Transgressive segregation created novel germination phenotypes, revealing a potential contribution of hybridization of ecotypes to the evolution of germination. A genetic trade-off in germination percentage across sites indicated that determinants of fitness at or before the germination stage may constrain the geographic range that a given genotype can inhabit. However, germination timing exhibited only weak pleiotropy across treatments, suggesting that different sets of genes contribute to variation in germination behavior in different seasonal conditions and geographic locations. Thus, the genetic potential exists for rapid evolution of appropriate germination responses in novel environments, facilitating colonization across a broad geographic range.
Arabidopsis↗
The evolutionary ecology of seed germination of Arabidopsis thaliana: variable natural selection on germination timing.
Germination timing of Arabidopsis thaliana displays strong plasticity to geographic location and seasonal conditions experienced by seeds. We identified which plastic responses were adaptive using recombinant inbred lines in a field manipulation of geographic location (Kentucky, KY; Rhode Island, RI), maternal photoperiod (14-h and 10-h days), and season of dispersal (June and November). Transgressive segregation created novel genotypes that had either higher fitness or lower fitness in certain environments than either parent. Natural selection on germination timing and its variation explained 72% of the variance in fitness among genotypes in KY, 30% in June-dispersed seeds in RI, but only 4% in November-dispersed seeds in RI. Therefore, natural selection on germination timing is an extremely efficient sieve that can determine which genotypes can persist in some locations, and its efficiency is geographically variable and depends on other aspects of life history. We found no evidence for adaptive responses to maternal photoperiod during seed maturation. We did find adaptive plasticity to season of seed dispersal in RI. Seeds dispersed in June postponed germination, which was adaptive, while seeds dispersed in November accelerated germination, which was also adaptive. We also found maladaptive plasticity to geographic location for seeds dispersed in June, such that seeds dispersed in KY germinated much sooner than the optimum time. Consequently, bet hedging in germination timing was favorable in KY; genotypes with more variation in germination timing had higher fitness because greater variation was associated with postponed germination. Selection on germination timing varied across geographic location, indicating that germination timing can be a critical stage in the establishment of genotypes in new locations. The rate of evolution of germination timing may therefore strongly influence the rate at which species can expand their range.
Adaptation, Physiological↗
Niche construction through germination cueing: life-history responses to timing of germination in Arabidopsis thaliana.
Germination responses to seasonal conditions determine the environment experienced by postgermination life stages, and this ability has potential consequences for the evolution of plant life histories. Using recombinant inbred lines of Arabidopsis thaliana, we tested whether life-history characters exhibited plasticity to germination timing, whether germination timing influenced the strength and mode of natural selection on life-history traits, and whether germination timing influenced the expression of genetic variation for life-history traits. Adult life-history traits exhibited strong plasticity to season of germination, and season of germination significantly altered the strength, mode, and even direction of selection on life-history traits under some conditions. None of the average plastic responses to season of germination or season of dispersal were adaptive, although some genotypes within our sample did exhibit adaptive responses. Thus, recombination between inbred lineages created some novel adaptive genotypes with improved responses to the seasonal timing of germination under some, but not all, conditions. Genetically based variation in germination time tended to augment genetic variances of adult life-history traits, but it did not increase the heritabilities because it also increased environmentally induced variance. Under some conditions, plasticity of life-history traits in response to genetically variable germination timing actually obscured genetic variation for those traits. Therefore, the evolution of germination responses can influence the evolution of life histories in a general manner by altering natural selection on life-history traits and the genetic variation of these traits.
Adaptation, Physiological↗
Upregulation of the tissue inhibitor of metalloproteinase-1 protein is associated with progression of human non-small-cell lung cancer.
PURPOSE: Tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring inhibitors of matrix metalloproteinases (MMPs). It has been shown that TIMP-1 may be a multifunctional protein. Little is known about the role of TIMP-1 in progression and metastasis of human lung cancer (tumor inhibiting or tumor promoting), although studies using a variety of techniques have analyzed the expression of TIMP-1 mRNA and/or protein in human cancers. PATIENTS AND METHODS: We examined the expression of TIMP-1 protein by immunohistochemistry in patients (n = 160) with primary respectable (stage I to IIIA) non-small-cell lung cancer (NSCLC). RESULTS: Twenty-seven percent of the tumors (43 of 160) demonstrated elevated expression of this protein. We demonstrate that overexpression of TIMP-1 protein is associated with an adverse outcome. In addition, disease stage, patient's age, and performance status were all significantly related to survival. In multivariate analyses, patients with high TIMP-1 expression had a 90% increased risk of death when compared with those with low expression (relative risk, 1.92; 95% CI, 1.19 to 3.09; P =.008). TIMP-1 expression did not correlate with expression of MMP-2 and MMP-9. CONCLUSION: These results suggest that TIMP-1, independent of its inhibiting activity of MMPs, may have other function(s) critical for NSCLCs. The significance of our results is two-fold. The adverse outcome in patients with overexpression of TIMP-1 indicates its potential prognostic value in NSCLC. Thus, TIMP-1 overexpression may serve to help identify patients with particularly aggressive disease for adjuvant treatments. In addition, the TIMP-1 molecule may represent a novel therapeutic target for treatment of some NSCLCs.
Adult↗
The influence of neighbor relatedness on multilevel selection in the Great Lakes sea rocket.
Natural selection can operate at the individual and group level in natural populations. This study investigates the ecological factors that determine the relative importance of individual versus group selection. In particular, it determines how the relatedness of interacting neighbors influences multilevel natural selection in a population of the Great Lakes sea rocket. Focal plants were grown in groups of siblings, groups of plants that were themselves siblings but unrelated to the focal plants, and groups of plants with mixed genotypes. Significant group selection on plant size was observed only when the neighbors were siblings but not when they were unrelated. In sibling groups, individuals with heavier stems had higher fitness, and individuals growing with heavier but shorter neighbors also had higher fitness. Thus, individual and group selection on stem weight operated in the same direction. The detection of group selection in sibling groups can be attributed in part to an increased opportunity for group selection in these groups since sibling groups differed more from one another than the other group types. In addition, the quality of the selective environment in sibling groups may have differed from that for the other group types. Group selection was therefore more prevalent in the most genetically structured sample, in which responses to group selection are also most likely to occur.
Analysis of Variance↗
Reducing environmental bias when measuring natural selection.
Crucial to understanding the process of natural selection is characterizing phenotypic selection. Measures of phenotypic selection can be biased by environmental variation among individuals that causes a spurious correlation between a trait and fitness. One solution is analyzing genotypic data, rather than phenotypic data. Genotypic data, however, are difficult to gather, can be gathered from few species, and typically have low statistical power. Environmental correlations may act through traits other than through fitness itself. A path analytic framework, which includes measures of such traits, may reduce environmental bias in estimates of selection coefficients. We tested the efficacy of path analysis to reduce bias by re-analyzing three experiments where both phenotypic and genotypic data were available. All three consisted of plant species (Impatiens capensis, Arabidopsis thaliana, and Raphanus sativus) grown in experimental plots or the greenhouse. We found that selection coefficients estimated by path analysis using phenotypic data were highly correlated with those based on genotypic data with little systematic bias in estimating the strength of selection. Although not a panacea, using path analysis can substantially reduce environmental biases in estimates of selection coefficients. Such confidence in phenotypic selection estimates is critical for progress in the study of natural selection.
Arabidopsis↗
Seed Dispersal as a Maternally Influenced Character: Mechanistic Basis of Maternal Effects and Selection on Maternal Characters in an Annual Plant.
Maternal influences on progeny characters affect phenotypic correlations between characters expressed in maternal and progeny generations and consequently influence evolutionary responses to selection. Net selection on maternally influenced characters depends on selection both on the progeny character and on the maternal characters that influence it. I used seed dispersal in Cakile edentula as a system in which to identify the mechanisms of environmentally mediated maternal effects and to determine how selection on maternal characters alters the adaptive value of dispersal. In C. edentula, maternal morphology responds to conspecific density experienced by the mother. Maternal morphology in turn affects offspring (seed) dispersal and density and thereby offspring morphology and fitness. I estimated the magnitude of density-mediated maternal effects on dispersal and identified their mechanism by characterizing the plasticity of maternal morphology to density. I also measured density-dependent selection on maternal characters that influence dispersal. Maternal plasticity to density was caused by both allometric and nonallometric variation in morphology, and this plasticity resulted in a negative correlation between maternal and progeny density. Such negative maternal effects are expected to retard responses to selection. Maternal morphology influenced maternal fitness, in part through the relationship of fitness to maternal plant size and in part through size-independent fitness effects. Maternal phenotypes that promote dispersal, and thereby increase progeny fitness, were associated with decreased maternal fitness. Selection on dispersal at the level of progeny favors increased dispersal; maternal influences on dispersal, however, not only cause a greatly reduced adaptive value of dispersal but lead to the prediction of a slower response to selection.
dispersal↗