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1.
Climacteric ; : 1-8, 2024 Sep 16.
Article in English | MEDLINE | ID: mdl-39279753

ABSTRACT

OBJECTIVE: Findings concerning the effects of hormone therapy (HT) on cognition and dementia are mixed, with some trials suggesting increased harm at older ages. Personality, like cognition, changes with dementia, but no clinical trials to date have examined the effects of HT on personality traits. This study aimed to determine the effects of HT on personality traits in older men and women. METHOD: Secondary data analysis was performed from randomized, double-blind, placebo-controlled cross-over studies of menopausal HT in women and testosterone therapy (TT) in men. Participants were community-dwelling cognitively normal adults (mean age = 75.2 years), including 29 men and 22 women. Three months of hormone intervention (for women, 0.625 mg/day conjugated equine estrogen with or without 2.5 mg/day medroxyprogesterone acetate; for men, 200 mg intramuscular testosterone enanthate every 2 weeks) were crossed over with 3 months of identical placebo with a 3-month washout between intervention phases. The main outcome measure was neuroticism and conscientiousness personality domains and facets assessed with the Revised NEO Personality Inventory (NEO-PI-R) after the active and placebo intervention phases. RESULTS: In linear mixed-effect models, HT in women decreased conscientiousness (p < 0.01) and the conscientiousness facet of achievement striving (p < 0.01), and increased vulnerability, a facet of neuroticism (p < 0.05). Testosterone in men decreased conscientiousness (p < 0.05) and the conscientiousness facet of dutifulness (p < 0.05), and increased vulnerability (p < 0.05). CONCLUSION: In a preliminary study of healthy older adults, HT and TT formulations produced adverse changes in vulnerability and conscientiousness facets that parallel personality changes in dementia.

2.
Front Aging Neurosci ; 16: 1426070, 2024.
Article in English | MEDLINE | ID: mdl-39044806

ABSTRACT

Background: Women carrying the APOE4 allele are at greater risk of developing Alzheimer's disease (AD) from ages 65-75 years compared to men. To better understand the elevated risk conferred by APOE4 carrier status among midlife women, we investigated the separate and interactive associations of endogenous estrogens, plasma AD biomarkers, and APOE4 carrier status on regional brain volumes in a sample of late midlife postmenopausal women. Methods: Participants were enrolled in MsBrain, a cohort study of postmenopausal women (n = 171, mean age = 59.4 years, mean MoCA score = 26.9; race = 83.2% white, APOE4 carriers = 40). Serum estrone (E1) and estradiol (E2) levels were assessed using liquid chromatography-tandem mass spectrometry. APOE genotype was determined using TaqMan SNP genotyping assays. Plasma AD biomarkers were measured using single molecule array technology. Cortical volume was measured and segmented by FreeSurfer software using individual T1w MPRAGE images. Multiple linear regression models were conducted to determine whether separate and interactive associations between endogenous estrogen levels, plasma AD biomarkers (Aß42/Aß40, Aß42/p-tau181), and APOE4 carrier status predict regional brain volume (21 regions per hemisphere, selected a priori); and, whether significant interactive associations between estrogens and AD biomarkers on brain volume differed by APOE4 carrier status. Results: There was no main effect of APOE4 carrier status on regional brain volumes, endogenous estrogen levels, or plasma AD biomarkers. Estrogens did not associate with regional brain volumes, except for positive associations with left caudal middle frontal gyrus and fusiform volumes. The interactive association of estrogens and APOE4 carrier status on brain volume was not significant for any region. The interactive association of estrogens and plasma AD biomarkers predicted brain volume of several regions. Higher E1 and E2 were more strongly associated with greater regional brain volumes among women with a poorer AD biomarker profile (lower Aß42/40, lower Aß42/p-tau181 ratios). In APOE4-stratified analyses, these interactions were driven by non-APOE4 carriers. Conclusion: We demonstrate that the brain volumes of postmenopausal women with poorer AD biomarker profiles benefit most from higher endogenous estrogen levels. These findings are driven by non-APOE4 carriers, suggesting that APOE4 carriers may be insensitive to the favorable effects of estrogens on brain volume in the postmenopause.

3.
Article in English | MEDLINE | ID: mdl-39026459

ABSTRACT

OBJECTIVE: Determine associations of endogenous estrogens with memory systems in the postmenopausal brain and evaluate clinical significance. STUDY DESIGN: In the MsBrain cohort (n=199, mean age 59.3+3.9 years, 83.9% white), we examined the cross-sectional association of serum estradiol and estrone, measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS), during a functional magnetic resonance imaging (fMRI) task of word encoding and recognition. To characterize the clinical significance of those associations, we examined the magnitude of activation in relation to a neuropsychological measures of memory and affect. RESULTS: Endogenous estradiol was positively associated with activation in temporal and frontal cortices during encoding and negatively associated with one prefrontal region during recognition (p<.05). Activation in the left inferior frontal gyrus was associated with memory performance (ß(SE)= 0.004(0.002), p<.05), and anxiety (ß(SE)= -0.100(0.050), p<.05). The left middle frontal gyrus was associated with memory performance (ß(SE)= 0.006(0.002), p<.01), depression, and anxiety. The left superior temporal gyrus (STG) was associated with depression (ß(SE)= -0.083(0.036), p<.05) and anxiety (ß(SE)= -0.134(0.058), p<.05). Estrone was positively associated with activation in a range of brain areas including bilateral STG and right superior frontal gyrus during encoding (p<.05). Activation of the left insula an precental gyrus were associated with symptoms of depression and anxiety. None related to memory. CONCLUSION: The function of brain areas critical to memory performance varies with estrogen levels in the postmenopause, even though those levels are low. Higher levels of estradiol may facilitate memory performance through enhanced function of temporal and frontal cortices during encoding of verbal material.

4.
Climacteric ; 27(4): 373-381, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38695574

ABSTRACT

OBJECTIVE: This study aimed to examine sex differences in factors associated with mood and anxiety in midlife men and women during the COVID-19 pandemic. METHODS: During a remote visit, 312 adults aged 40-60 years (167 female; 23.6% perimenopausal) from the Human Connectome Project in Aging completed PROMIS measures of depression, anxiety and anger/irritability; perceived stress; and questions about social support, financial stress and menopause stage. Multivariate linear regression models assessed sex differences in mental health and the association of social support, financial stress and menopause stage with mental health. RESULTS: Anxiety was higher in women than in men (b = 2.39, p = 0.02). For women only, decreased social support was associated with increased anxiety (b = -2.26, p = 0.002), anger/irritability (b = -1.89, p = 0.02) and stress (b = -1.67, p = 0.002). For women only, not having close family was associated with increased depressive symptoms (b = -6.60, p = 0.01) and stress (b = -7.03, p < 0.001). For both sexes, having children was associated with lower depressive symptoms (b = -3.08, p = 0.002), anxiety (b = -1.93, p = 0.07), anger/irritability (b = -2.73, p = 0.02) and stress (b = -1.44, p = 0.07). Menopause stage was unrelated to mental health. CONCLUSION: Social support, but not financial stress, influenced mental health during the COVID-19 pandemic at midlife, particularly for women.


Subject(s)
Anxiety , COVID-19 , Depression , Menopause , Mental Health , SARS-CoV-2 , Social Support , Humans , COVID-19/psychology , COVID-19/epidemiology , Female , Middle Aged , Male , Adult , Anxiety/psychology , Anxiety/epidemiology , Depression/psychology , Depression/epidemiology , Menopause/psychology , Sex Factors , Stress, Psychological/psychology , Anger , Pandemics , Financial Stress/psychology
5.
Behav Brain Res ; 416: 113558, 2022 01 07.
Article in English | MEDLINE | ID: mdl-34453970

ABSTRACT

Chronic stress during pregnancy harms both the mother and developing child, and there is an urgent unmet need to understand this process in order to develop protective treatments. Here, we report that chronic gestational stress (CGS) causes aberrant maternal care behavior in the form of increased licking and grooming, decreased nursing, and increased time spent nest building. Treatment of CGS-exposed dams with the NAD+-stabilizing agent P7C3-A20 during pregnancy and postpartum, however, preserved normal maternal care behavior. CGS also caused abnormally low weight gain during gestation and postpartum, which was partially ameliorated by maternal treatment with P7C3-A20. Dams also displayed hyperactive locomotion after CGS, which was not affected by P7C3-A20. Although dams did not display a classic depressive-like phenotype after CGS, some changes in anxiety- and depressive-like behaviors were observed. Our results highlight the need for further characterization of the effects of chronic gestational stress on maternal care behavior and provide clues to possible protective mechanisms.


Subject(s)
Behavior, Animal/drug effects , Carbazoles/pharmacology , Maternal Behavior/drug effects , Neuroprotection , Postpartum Period/drug effects , Stress, Psychological/drug therapy , Animals , Anxiety , Disease Models, Animal , Female , Humans , Pregnancy
6.
Antioxid Redox Signal ; 35(7): 511-530, 2021 09 01.
Article in English | MEDLINE | ID: mdl-33501899

ABSTRACT

Aims: Impaired embryonic cortical interneuron development from prenatal stress is linked to adult neuropsychiatric impairment, stemming in part from excessive generation of reactive oxygen species in the developing embryo. Unfortunately, there are no preventive medicines that mitigate the risk of prenatal stress to the embryo, as the underlying pathophysiologic mechanisms are poorly understood. Our goal was to interrogate the molecular basis of prenatal stress-mediated damage to the embryonic brain to identify a neuroprotective strategy. Results: Chronic prenatal stress in mice dysregulated nicotinamide adenine dinucleotide (NAD+) synthesis enzymes and cortical interneuron development in the embryonic brain, leading to axonal degeneration in the hippocampus, cognitive deficits, and depression-like behavior in adulthood. Offspring were protected from these deleterious effects by concurrent maternal administration of the NAD+-modulating agent P7C3-A20, which crossed the placenta to access the embryonic brain. Prenatal stress also produced axonal degeneration in the adult corpus callosum, which was not prevented by maternal P7C3-A20. Innovation: Prenatal stress dysregulates gene expression of NAD+-synthesis machinery and GABAergic interneuron development in the embryonic brain, which is associated with adult cognitive impairment and depression-like behavior. We establish a maternally directed treatment that protects offspring from these effects of prenatal stress. Conclusion: NAD+-synthesis machinery and GABAergic interneuron development are critical to proper embryonic brain development underlying postnatal neuropsychiatric functioning, and these systems are highly susceptible to prenatal stress. Pharmacologic stabilization of NAD+ in the stressed embryonic brain may provide a neuroprotective strategy that preserves normal embryonic development and protects offspring from neuropsychiatric impairment. Antioxid. Redox Signal. 35, 511-530.


Subject(s)
Cognitive Dysfunction , Neuroprotective Agents , Prenatal Exposure Delayed Effects , Animals , Carbazoles/pharmacology , Carbazoles/therapeutic use , Female , Hippocampus , Mice , Neurogenesis , Neuroprotective Agents/pharmacology , Pregnancy , Prenatal Exposure Delayed Effects/drug therapy , Stress, Psychological/complications
7.
Proc Natl Acad Sci U S A ; 117(44): 27667-27675, 2020 11 03.
Article in English | MEDLINE | ID: mdl-33087571

ABSTRACT

Chronic neurodegeneration in survivors of traumatic brain injury (TBI) is a major cause of morbidity, with no effective therapies to mitigate this progressive and debilitating form of nerve cell death. Here, we report that pharmacologic restoration of the blood-brain barrier (BBB), 12 mo after murine TBI, is associated with arrested axonal neurodegeneration and cognitive recovery, benefits that persisted for months after treatment cessation. Recovery was achieved by 30 d of once-daily administration of P7C3-A20, a compound that stabilizes cellular energy levels. Four months after P7C3-A20, electron microscopy revealed full repair of TBI-induced breaks in cortical and hippocampal BBB endothelium. Immunohistochemical staining identified additional benefits of P7C3-A20, including restoration of normal BBB endothelium length, increased brain capillary pericyte density, increased expression of BBB tight junction proteins, reduced brain infiltration of immunoglobulin, and attenuated neuroinflammation. These changes were accompanied by cessation of TBI-induced chronic axonal degeneration. Specificity for P7C3-A20 action on the endothelium was confirmed by protection of cultured human brain microvascular endothelial cells from hydrogen peroxide-induced cell death, as well as preservation of BBB integrity in mice after exposure to toxic levels of lipopolysaccharide. P7C3-A20 also protected mice from BBB degradation after acute TBI. Collectively, our results provide insights into the pathophysiologic mechanisms behind chronic neurodegeneration after TBI, along with a putative treatment strategy. Because TBI increases the risks of other forms of neurodegeneration involving BBB deterioration (e.g., Alzheimer's disease, Parkinson's disease, vascular dementia, chronic traumatic encephalopathy), P7C3-A20 may have widespread clinical utility in the setting of neurodegenerative conditions.


Subject(s)
Blood-Brain Barrier/drug effects , Brain Injuries, Traumatic/drug therapy , Carbazoles/pharmacology , Cognition/drug effects , Neurodegenerative Diseases/drug therapy , Neuroprotective Agents/pharmacology , Animals , Behavior, Animal/drug effects , Behavior, Animal/physiology , Blood-Brain Barrier/cytology , Blood-Brain Barrier/pathology , Blood-Brain Barrier/ultrastructure , Brain Injuries, Traumatic/complications , Brain Injuries, Traumatic/pathology , Carbazoles/therapeutic use , Cells, Cultured , Chronic Disease/drug therapy , Cognition/physiology , Disease Models, Animal , Endothelial Cells , Endothelium, Vascular/cytology , Endothelium, Vascular/drug effects , Endothelium, Vascular/pathology , Humans , Male , Mice , Microscopy, Electron , Microvessels/cytology , Neurodegenerative Diseases/etiology , Neurodegenerative Diseases/pathology , Neurodegenerative Diseases/physiopathology , Neuroprotective Agents/therapeutic use , Primary Cell Culture , Survivors
8.
JAMA Pediatr ; 173(10): e192574, 2019 Oct 01.
Article in English | MEDLINE | ID: mdl-31403684

ABSTRACT

IMPORTANCE: Use of electronic cigarettes (often called e-cigarettes) has increased considerably among young people in the past 5 years. Use of e-cigarettes has been associated with higher rates of marijuana use, which is associated with several adverse health outcomes in youth. OBJECTIVE: To characterize and quantify the association between e-cigarette and marijuana use among youth using a meta-analysis. DATA SOURCES: PubMed, Embase, and Web of Science & ProQuest Dissertations and Theses were searched from inception to October 2018. A gray-literature search was also conducted on conference abstracts, government reports, and other sources. STUDY SELECTION: Included studies compared rates of marijuana use among youth aged 10 to 24 years who had used e-cigarettes vs those who had not used e-cigarettes. Two reviewers independently assessed studies for inclusion; disagreements were discussed with a third reviewer and resolved by consensus. DATA EXTRACTION AND SYNTHESIS: Data were extracted by 2 independent reviewers following Meta-analyses of Observational Studies in Epidemiology (MOOSE) reporting guidelines and pooled using a random-effects analysis. The Newcastle-Ottawa Scale was used to assess data quality and validity of individual studies. MAIN OUTCOMES AND MEASURES: Adjusted odds ratios (AORs) of self-reported past or current marijuana use by youth with vs without past or current e-cigarette use. RESULTS: Twenty-one of 835 initially identified studies (2.5%) met selection criteria. The meta-analysis included 3 longitudinal and 18 cross-sectional studies that included 128 227 participants. Odds of marijuana use were higher in youth who had an e-cigarette use history vs those who did not (AOR, 3.47 [95% CI, 2.63-4.59]; I2, 94%). Odds of marijuana use were significantly increased in youth who used e-cigarettes in both longitudinal studies (3 studies; AOR, 2.43 [95% CI, 1.51-3.90]; I2, 74%) and cross-sectional studies (18 studies; AOR, 3.70 [95% CI, 2.76-4.96]; I2, 94%). Odds of using marijuana in youth with e-cigarette use were higher in adolescents aged 12 to 17 years (AOR, 4.29 [95% CI, 3.14-5.87]; I2, 94%) than young adults aged 18 to 24 years (AOR, 2.30 [95% CI, 1.40-3.79]; I2, 91%). CONCLUSIONS AND RELEVANCE: This meta-analysis found a significant increase in the odds of past or current and subsequent marijuana use in adolescents and young adults who used e-cigarettes. These findings highlight the importance of addressing the rapid increases in e-cigarette use among youths as a means to help limit marijuana use in this population.

9.
Neurosci Lett ; 709: 134368, 2019 09 14.
Article in English | MEDLINE | ID: mdl-31299286

ABSTRACT

Development of the brain prenatally is affected by maternal experience and exposure. Prenatal maternal psychological stress changes brain development and results in increased risk for neuropsychiatric disorders. In this review, multiple levels of prenatal stress mechanisms (offspring brain, placenta, and maternal physiology) are discussed and their intersection with cellular stress mechanisms explicated. Heat shock factors and oxidative stress are closely related to each other and converge with the inflammation, hormones, and cellular development that have been more deeply explored as the basis of prenatal stress risk. Increasing evidence implicates cellular stress mechanisms in neuropsychiatric disorders associated with prenatal stress including affective disorders, schizophrenia, and child-onset psychiatric disorders. Heat shock factors and oxidative stress also have links with the mechanisms involved in other kinds of prenatal stress including external exposures such as environmental toxicants and internal disruptions such as preeclampsia. Integrative understanding of developmental neurobiology with these cellular and physiological mechanisms is necessary to reduce risks and promote healthy brain development.


Subject(s)
Brain/metabolism , Heat-Shock Proteins/metabolism , Heat-Shock Response/physiology , Oxidative Stress/physiology , Prenatal Exposure Delayed Effects/metabolism , Stress, Psychological/metabolism , Animals , Brain/growth & development , Female , Humans , Pregnancy , Prenatal Exposure Delayed Effects/etiology , Prenatal Exposure Delayed Effects/psychology , Stress, Psychological/complications , Stress, Psychological/psychology
10.
ACS Chem Neurosci ; 10(3): 1595-1602, 2019 03 20.
Article in English | MEDLINE | ID: mdl-30421909

ABSTRACT

Compounds targeting the sigma 2 receptor, which we recently cloned and showed to be identical with transmembrane protein 97 (σ2R/TMEM97), are broadly applicable therapeutic agents currently in clinical trials for imaging in breast cancer and for treatment of Alzheimer's disease and schizophrenia. These promising applications coupled with our previous observation that the σ2R/TMEM97 modulator SAS-0132 has neuroprotective attributes and improves cognition in wild-type mice suggests that modulating σ2R/TMEM97 may also have therapeutic benefits in other neurodegenerative conditions such as traumatic brain injury (TBI). Herein, we report that DKR-1677, a novel derivative of SAS-0132 with increased affinity and selectivity for σ2R/Tmem97 ( Ki = 5.1 nM), is neuroprotective after blast-induced and controlled cortical impact (CCI) TBI in mice. Specifically, we discovered that treatment with DKR-1677 decreases axonal degeneration after blast-induced TBI and enhances survival of cortical neurons and oligodendrocytes after CCI injury. Furthermore, treatment with DKR-1677 preserves cognition in the Morris water maze after blast TBI. Our results support an increasingly broad role for σ2R/Tmem97 modulation in neuroprotection and suggest a new approach for treating patients suffering from TBI.


Subject(s)
Brain Injuries, Traumatic/drug therapy , Membrane Proteins/drug effects , Neuroprotective Agents/pharmacology , Receptors, sigma/drug effects , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Animals , Cognition/drug effects , Disease Models, Animal , Neurons/drug effects
11.
J Womens Health (Larchmt) ; 27(8): 965-973, 2018 08.
Article in English | MEDLINE | ID: mdl-30129895

ABSTRACT

Migraine is a common chronic neurological disease that disproportionately affects women. Migraine has significant negative effects on physical, emotional, and social aspects of health, and can be costly for patients, employers, and society as a whole. Growing evidence supports the roles of sex and gender in migraine risk, pathophysiology, presentation, diagnosis, treatment, and management. However, sex and gender differences in migraine have received limited attention, which can impede advancements in migraine detection, treatment, care, and education. The Society for Women's Health Research convened an interdisciplinary expert panel of researchers, clinicians, and advocates for a roundtable meeting to review the current research on sex and gender differences in migraine. This review summarizes discussions from the roundtable and prioritizes areas of need that warrant further attention in migraine research, care, and education. Examining sex and gender differences in migraine and addressing knowledge gaps will decrease the health and economic burden of migraine for both women and men.


Subject(s)
Headache/physiopathology , Migraine Disorders/physiopathology , Women's Health , Biomedical Research , Female , Headache/psychology , Health Knowledge, Attitudes, Practice , Humans , Male , Migraine Disorders/psychology , Research Report , Sex Factors , Social Stigma , Societies, Medical
12.
Curr Pharm Des ; 22(14): 1981-5, 2016.
Article in English | MEDLINE | ID: mdl-26818870

ABSTRACT

The frequency of neuropsychiatric disorders is greater than that of cancer, cardiovascular disease, and diabetes combined, and is growing at a faster rate than any other ailments in the United States or Europe. Despite a considerable need for the development of treatments for central nervous system disorders, pharmaceutical companies continue to reduce investment in this area of research. Of particular concern is the treatment of diseases and disorders that affect cognitive function, which are often given a lower priority for research investment than life threatening conditions or those with overt physical symptoms. Several reasons exist for this reduced investment, including a poor understanding of the mechanisms underlying impaired cognitive function, costly and long periods of development for these medications, disproportionately lower success rates, and a stigma associated with the medical treatment of mental illness. This paper will discuss these issues, review some of the successes resulting from research investment and discuss opportunities that should encourage increased research investment in cognitive disorders and their treatment.


Subject(s)
Cholinergic Agents/therapeutic use , Cognition Disorders/drug therapy , Animals , Cognition/drug effects , Humans
13.
New Phytol ; 200(3): 788-795, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23638943

ABSTRACT

Increasing atmospheric CO2 concentrations alter leaf physiology, with effects that cascade to communities and ecosystems. Yet, responses over cycles of disturbance and recovery are not well known, because most experiments span limited ecological time. We examined the effects of CO2 on root growth, herbivory and arthropod biodiversity in a woodland from 1996 to 2006, and the legacy of CO2 enrichment on these processes during the year after the CO2 treatment ceased. We used minirhizotrons to study root growth, leaf censuses to study herbivory and pitfall traps to determine the effects of elevated CO2 on arthropod biodiversity. Elevated CO2 increased fine root biomass, but decreased foliar nitrogen and herbivory on all plant species. Insect biodiversity was unchanged in elevated CO2. Legacy effects of elevated CO2 disappeared quickly as fine root growth, foliar nitrogen and herbivory levels recovered in the next growing season following the cessation of elevated CO2. Although the effects of elevated CO2 cascade through plants to herbivores, they do not reach other trophic levels, and biodiversity remains unchanged. The legacy of 10 yr of elevated CO2 on plant-herbivore interactions in this system appear to be minimal, indicating that the effects of elevated CO2 may not accumulate over cycles of disturbance and recovery.


Subject(s)
Carbon Dioxide/metabolism , Ecosystem , Herbivory , Insecta , Plant Roots/growth & development , Quercus/physiology , Trees/physiology , Animals , Atmosphere , Biodiversity , Biomass , Nitrogen/metabolism , Plant Leaves/metabolism , Quercus/growth & development , Quercus/metabolism , Seasons , Trees/growth & development , Trees/metabolism
14.
New Phytol ; 200(3): 778-787, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23528147

ABSTRACT

Uncertainty surrounds belowground plant responses to rising atmospheric CO2 because roots are difficult to measure, requiring frequent monitoring as a result of fine root dynamics and long-term monitoring as a result of sensitivity to resource availability. We report belowground plant responses of a scrub-oak ecosystem in Florida exposed to 11 yr of elevated atmospheric CO2 using open-top chambers. We measured fine root production, turnover and biomass using minirhizotrons, coarse root biomass using ground-penetrating radar and total root biomass using soil cores. Total root biomass was greater in elevated than in ambient plots, and the absolute difference was larger than the difference aboveground. Fine root biomass fluctuated by more than a factor of two, with no unidirectional temporal trend, whereas leaf biomass accumulated monotonically. Strong increases in fine root biomass with elevated CO2 occurred after fire and hurricane disturbance. Leaf biomass also exhibited stronger responses following hurricanes. Responses after fire and hurricanes suggest that disturbance promotes the growth responses of plants to elevated CO2. Increased resource availability associated with disturbance (nutrients, water, space) may facilitate greater responses of roots to elevated CO2. The disappearance of responses in fine roots suggests limits on the capacity of root systems to respond to CO2 enrichment.


Subject(s)
Biomass , Carbon Dioxide/metabolism , Ecosystem , Environment , Plant Roots/growth & development , Quercus/growth & development , Trees/growth & development , Atmosphere , Cyclonic Storms , Fires , Florida , Plant Leaves/growth & development , Plant Roots/metabolism , Quercus/metabolism , Trees/metabolism
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