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1.
Changes in hematological and serum chemistry values have been identified among older compared to younger humans. We hypothesized that healthy bottlenose dolphins (Tursiops truncatus) 30 years and older may demonstrate similar clinicopathological changes with increasing age. Retrospective hematological and serum chemistry data generated from routine, fasted blood samples collected over 10 to 20 years among six healthy dolphins that lived at least 40 years were analyzed to (1) assess linear trends in blood variable values with increasing age, (2) compare mean blood values by older age categories (30–35 years, 36–40 years, and >40 years), and (3) compare the prevalence of clinically high or low blood values by older age categories. Absolute lymphocytes, serum globulins, and mean platelet volume increased linearly with increasing old age. Mean white blood cells, neutrophils, serum globulins, erythrocyte sedimentation rates, serum cholesterol, and serum triglycerides; and the prevalence of neutrophilic leukocytosis, hyperglobulinemia, and hypercholesterolemia, were more likely to be higher as geriatric dolphins got older. A linear decrease in serum albumin with increasing age was present for five of six animals. Serum creatinine decreased among dolphins older than 40 years compared to when they were 30–40 years old. Our study demonstrates that older dolphins have changes in hematological and serum chemistry values similar to those found in older humans. As such, bottlenose dolphins may serve as a useful comparative model for aging in humans. Further studies are needed to assess whether these changes are associated with negative health outcomes and whether targeted therapeutics can help improve quality of life among aging dolphins.  相似文献   

2.
We report excavations of an abandoned penguin colony on Byers Peninsula, Livingston Island, Antarctica, in austral summer 2008/2009. Nine abandoned pebble mounds were located on Devils Point, near an active Gentoo Penguin (Pygoscelis papua) colony of about 3,000 nests, at an elevation of 40–45 m above sea level. Three of the nine mounds were excavated to recover organic remains for radiocarbon and ancient DNA analyses; two additional mounds were probed to obtain tissue samples for additional dating. All radiocarbon dates were corrected for the marine-carbon reservoir effect using a ΔR of 700 ± 50 years. Calibrated 2-sigma ranges in calendar years before present (B.P.) on 23 samples of egg membrane and bone provided an overall range of 40–1,150 B.P., with most of the dates falling between 225 and 465 B.P. Ancient DNA analysis confirmed that the tissues recovered from these excavations represent Gentoo Penguin. One radiocarbon date from the active Gentoo Penguin colony indicated an age of 285–480 B.P. for the initiation of this current occupation and corresponding in age with most of the abandoned mounds. Although geologic evidence indicates that Byers Peninsula has been ice free for at least 3,000 years, these results indicate that penguin occupation lagged behind deglaciation by over 2,000 years. Small numbers of Chinstrap Penguins (P. antarctica) also occupy the same breeding colonies as Gentoo Penguins at Byers Peninsula, but their absence in the ancient sediments suggests that they have only recently colonized this area.  相似文献   

3.
In the present study, we used the Comet assay to estimate basal DNA damage in three distinct populations aged 5–10, 40–50, and 60–70 years old. The DNA damage induced by hydrogen peroxide and γ-irradiation in the lymphocytes of these populations, as well as their repair activity, was also studied. Finally, we measured apoptosis and necrosis after the effect of these agents. Our results indicate that the older population (60–70 years old) showed higher basal levels of DNA damage and was more sensitive to the effects of the DNA-damaging agents than the adult one (40–50 years old), who, in turn, was more sensitive than the younger population (5–10 years old). A decline of the repair efficiency with age to the DNA damage induced by the two agents was also observed. Apoptosis and necrosis were also affected by age.  相似文献   

4.
Background: The peak incidence of Ewing sarcoma (EWS) is in adolescence, with little known about patients who are ≥40 years at diagnosis. We describe the clinical characteristics and survival of this rare group. Methods: This retrospective cohort study utilized the Surveillance Epidemiology and End Results database. 2780 patients were identified; including 383 patients diagnosed ≥40 years. Patient characteristics between age groups were compared using chi-squared tests. Survival from diagnosis to death was estimated via Kaplan–Meier methods, compared with log-rank tests, and modeled using multivariable Cox methods. A competing risks analysis was performed to evaluate death due to cancer. Results: Patients ≥40 years of age were more likely to have extra-skeletal tumors (66.1% vs. 31.7%; p < 0.001), axial tumors (64.0% vs. 57.2%; p = 0.01), and metastatic disease at diagnosis (35.5% vs. 30.0%; p = 0.04) compared to younger patients. Five-year survival for those age ≥40 and age <40 were 40.6% and 54.3%, respectively (p < 0.0001). A Cox multivariable model controlling for differences between groups confirmed inferior survival for older patients (hazard ratio for death of 2.04; 95% CI 1.63–2.54; p < 0.0001); though treatment data were unavailable and not controlled for in the model. A competing risks analysis confirmed increased risk of cancer-related death in older patients. Conclusion: Patients ≥40 years at diagnosis with EWS are more likely to have extra-skeletal tumors, metastatic disease, and axial primary tumors suggesting a difference in tumor biology. Independent of differences in these characteristics, older patients also have a lower survival rate.  相似文献   

5.
We examined the association between maternal age and chromosome 21 nondisjunction by origin of the meiotic error. We analyzed data from two population-based, case–control studies: Atlanta Down Syndrome Project (1989–1999) and National Down Syndrome Project (2001–2004). Cases were live born infants with trisomy 21 and controls were infants without trisomy 21 delivered in the same geographical regions. We enrolled 1,215 of 1,881 eligible case families and 1,375 of 2,293 controls. We report four primary findings. First, the significant association between advanced maternal age and chromosome 21 nondisjunction was restricted to meiotic errors in the egg; the association was not observed in sperm or in post-zygotic mitotic errors. Second, advanced maternal age was significantly associated with both meiosis I (MI) and meiosis II (MII). For example, compared to mothers of controls, mothers of infants with trisomy 21 due to MI nondisjunction were 8.5 times more likely to be ≥40 years old than 20–24 years old at the birth of the index case (95% CI = 5.6–12.9). Where nondisjunction occurred in MII, mothers were 15.1 times more likely to be ≥40 years (95% CI = 8.4–27.3). Third, the ratio of MI to MII errors differed by maternal age. The ratio was lower among women <19 years of age and those ≥40 years (2.1, 2.3, respectively) and higher in the middle age group (3.6). Lastly, we found no effect of grand-maternal age on the risk for maternal nondisjunction. This study emphasizes the complex association between advanced maternal age and nondisjunction of chromosome 21 during oogenesis. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.  相似文献   

6.
This research represents the first age‐based demographic assessment of pearl perch, Glaucosoma scapulare (Ramsay, 1881), a highly valued species endemic to coastal waters off central eastern Australia. The study was conducted across the species' distribution that encompasses two state jurisdictions (Queensland in the north and New South Wales in the south) using data collected approximately 10 years apart in each state. Estimates of age were made by counting annuli (validated using marginal increment ratios) in sectioned sagittal otoliths. The maximum estimated age was 19 years. Pearl perch attained approx. 12 cm fork length (FL) after one year, 21 cm FL after 2 years and 29 cm FL after 3 years. Fish from the southern end of the species' distribution grew significantly more slowly than those from the northern part of its range. Commercial landings in the north were characterized by greater proportions of larger (>40 cm FL) and older (>6 years) fish than those in the south, with landings mainly of fish between 3 and 6 years of age. The observed variations in age‐based demographics of pearl perch highlight the need for a better understanding of patterns of movement and reproduction in developing a model of population dynamics and life‐history for this important species. There is a clear need for further, concurrent, age‐based studies on pearl perch in the northern and southern parts of its distribution to support the conclusions of the present study based on data collected a decade apart.  相似文献   

7.
Tree species composition and structure of a 40-year chronosequence of secondary forests was compared with old-growth forests in southern Bahia, Brazil. Twelve stands were randomly selected that represented three age classes: 10, 25, and 40 year old with four replications in each class. All stands selected had been established after abandonment from swidden cultivation and were surrounded by old-growth forests. In every stand, ten 0.01-ha transects were established and all stems (≥5 cm diameter at breast height) were measured and identified. Results were compared with the dataset of two neighboring old-growth sites. Mean diameter, total height, and stand basal area increased with age. Number of trees/ha peaked in 40 year old stands. The results showed that secondary forests in this region take much more than 40 years to recover the structure of old-growth forests. In contrast, species richness recovery was rapid with a continuous accumulation of species with age in secondary forests. Species richness and diversity increased with age as did similarity between secondary stands and old-growth stands. More than half of the species found in the 40 year old stands were shared with the neighboring old-growth forests. However, species richness and diversity were higher in old growth sites.  相似文献   

8.
We evaluated the “4 per 1000” initiative for increasing soil organic carbon (SOC) by analysing rates of SOC increase in treatments in 16 long‐term experiments in southeast United Kingdom. The initiative sets a goal for SOC stock to increase by 4‰ per year in the 0–40 cm soil depth, continued over 20 years. Our experiments, on three soil types, provided 114 treatment comparisons over 7–157 years. Treatments included organic additions (incorporated by inversion ploughing), N fertilizers, introducing pasture leys into continuous arable systems, and converting arable land to woodland. In 65% of cases, SOC increases occurred at >7‰ per year in the 0–23 cm depth, approximately equivalent to 4‰ per year in the 0–40 cm depth. In the two longest running experiments (>150 years), annual farmyard manure (FYM) applications at 35 t fresh material per hectare (equivalent to approx. 3.2 t organic C/ha/year) gave SOC increases of 18‰ and 43‰ per year in the 23 cm depth during the first 20 years. Increases exceeding 7‰ per year continued for 40–60 years. In other experiments, with FYM applied at lower rates or not every year, there were increases of 3‰–8‰ per year over several decades. Other treatments gave increases between zero and 19‰ per year over various periods. We conclude that there are severe limitations to achieving the “4 per 1000” goal in practical agriculture over large areas. The reasons include (1) farmers not having the necessary resources (e.g. insufficient manure); (2) some, though not all, practices favouring SOC already widely adopted; (3) practices uneconomic for farmers—potentially overcome by changes in regulations or subsidies; (4) practices undesirable for global food security. We suggest it is more realistic to promote practices for increasing SOC based on improving soil quality and functioning as small increases can have disproportionately large beneficial impacts, though not necessarily translating into increased crop yield.  相似文献   

9.
IntroductionPulmonary embolism during pregnancy is a leading cause of maternal mortality. The aim of our study was to evaluate pregnant women with suspected pulmonary embolism prevalence of lesions on the lung perfusion as well as the relationship between the parenchymal lesions and various clinical factors and biological risk.MethodsThis is a retrospective study of 116 pregnant patients referred for suspected pulmonary embolism. The median age was 30 years, ranging from 15 to 47 years and the median gestational term was 31 weeks with a range of 12 to 40 weeks. Suspicion of pulmonary embolism was established with the presence of clinical signs (dyspnea, chest pain and palpitations). No patient had received a chest radiograph. The patients underwent planar perfusion scintigraphy with injected activity of 40 to 50 MBq of macroaggregates of human albumin (MAA) labeled with 99mTc. The scintigraphic results were classified according to the PIOPED criteria, depending on the likelihood of EP. The scans with low or intermediate probability were included in the same group, that of indeterminate results.ResultsThe scan was positive (with high probability) in 16 patients (13.8%), normal in 78 patients (67.2%) and classified as inconclusive in 22 patients (18.9%). In 16 patients with a positive scan, the lesions were interested the left lung in 10 cases (62.5%), the right lung in 1 case (6.25%) and were bilateral in 5 cases (31.25%).ConclusionsIn cases of suspected pulmonary embolism in a pregnant woman, the choice of imaging technique depends on both its diagnostic value and also its adverse effects. Lung scintigraphy is the examination to be carried out first in pregnant women with a chest radiograph. In others, it is that angiography should be performed as first line.  相似文献   

10.
Evaluations about social preferences for ecosystem services do not always include human well-being. Using a case study in South-Central Chile, we showed how the human well-being approach might reveal social preferences on ecosystem services. We used a socio-cultural approach to compare social preferences for provisioning, regulating, and cultural services and the links people establish to human well-being. From an online questionnaire, we collected 214 responses, balanced in gender (49/51 % men/women, respectively), diverse in age (18 to 62 years), but with 68 % under 30 years. Water for human consumption and agriculture, food, and native forest products were the most preferred provisioning services (40, 28, and 21 %, respectively). In contrast, products from tree plantations were considered the lowest ones. Pollution control (40 %) and water provision during summer (18 %) were the preferred regulating services, while biodiversity conservation (25 %) and environmental education (22 %) were primarily selected cultural ones. We found a clear preference pattern for provisioning services but not for regulating and cultural services. Even though people linked multiple ES to human well-being, some links’ patterns mirrored preferences for provisioning services but not for regulating and cultural services. However, although cultural services did not show a clear preference pattern, people perceived their importance by linking them to various benefits. Understanding social preferences of ES based on their links with human well-being helps to address their relevance and potential trade-offs for land planning and management decision-making and convert the ES concept into decision-making instruments.  相似文献   

11.
ObjectiveIn France, the national breast cancer screening programme (NBCSP), targeting women aged 50–74 years was rolled out nationwide in 2004. It aims at reducing breast cancer mortality. In addition to the NBCSP, the use of opportunistic screening is permitted in France. The objective of this study is to estimate both opportunistic use and overall coverage rates of breast cancer screening, among women 40–84 years of age, in France.MethodsThe French medico-administrative health data system (SNDS) was used to identify women performing an opportunistic or organised mammography screening in France in 2016–2017.ResultsThe two-yearly opportunistic mammography screening is 18 % among women aged 40–84; it is 11 % among women aged 50–74, i.e., the target age range for organised screening, 36 % among women aged 40–49 and 13 % among women aged 75–84. The overall two-yearly screening coverage is 48 % for all women aged 40–84; it is 60 % among women aged 50–74, 36 % among women 40–49 and 16 % for those aged 75–84. Geographical variations in screening are lessened when the two screening strategies are considered, as they balance each other.ConclusionAlthough coverage in the NBCSP is around 50 % in France, more than one third of the women make use of opportunistic screening within and outside the target age range. Organized screening appears to improve equity of access to mammography screening service. The lack of data on opportunistic screening practices hinders the evaluation of French screening practices as a whole.  相似文献   

12.
Area of bamboo forest (Phyllostachys praecox) has rapidly increased in southern China during the last 20 years due to its high economic value. Aims of this study were to analyse the temporal and spatial variations of soil organic matter (SOM) in heavily winter mulched bamboo stands and to estimate potential for carbon sequestration. Total of 60 soil profiles with 0–15 years of bamboo plantation were sampled from three towns in Lin’an County. Results showed that with increased plantation years, SOM decreased slightly at the beginning (1–5 years), and then rose up steadily. Based on the average of the three locations, the highest SOM content of 75.82 g/kg was the surface layer (0–10 cm) of the 15 years. As plantation year increased, the variation of SOM in the surface layer (0–10 cm) was represented by a parabolic shape, and in the second layer (10–20 cm), it was a similar mode, but less vigorous. Soil organic carbon (SOC) storage significantly increased during 5 to 15 years after it reached full production, and the calculated annual SOC increment in 0–40 cm soil profile was about 6.3 t C/ha/year. Therefore, extended Phyllostachys praecox forests can be considered as one option for countering CO2 emissions and regional climate change.  相似文献   

13.
The vertical 137Cs profile of forest and wasteland soils was analyzed in the south of the Podlasie Lowland area (Eastern Poland) about 20 years after the Chernobyl accident. In addition, the concentration of 40K in soils of the investigated area was measured. Below the litter layer (mean thickness 3 cm), the soil samples were collected up to a depth of 12 cm and then divided into three layers: 0–3, 3–7, 7–12 cm. The behavior of 137Cs and 40K isotopes in soils was analyzed depending on the depth from which the soil samples were collected, as well as on the content of organic carbon, pH of soil and its granulometric composition. It was established that the density of 137Cs in the litter layer equals 2.17 kBq m−2; it is the highest in layer 0–3 cm where it equals 3.44 kBq m−2, and it decreases with the depth to the value of 0.76 kBq m−2 in layer 7–12 cm. No similar pattern was observed in wasteland soils. The concentrations of 40K in forest and wasteland soils did not change significantly with depth.  相似文献   

14.
Free fatty acid receptor 1 (FFA1 or GPR40) has been studied for many years as a target for the treatment of type 2 diabetes mellitus. In order to increase potency and reduce hepatotoxicity, a series of novel compounds containing imidazo[1,2-a]pyridine scaffold as GPR40 agonist were synthesized. Compound I-14 was identified as an effective agonist as shown by the conspicuous drop in blood glucose in normal and diabetic mice. It had no risk of hepatotoxicity compared with TAK-875. Moreover, good pharmacokinetic (PK) properties of I-14 were observed (CL = 27.26 ml/h/kg, t1/2 = 5.93 h). The results indicate that I-14 could serve as a possible candidate to treat diabetes.  相似文献   

15.
Background: There is no agreement on the usefulness of the prostate-specific antigen (PSA) test for prostate cancer screening in young men in Japan. We believe that medical check-up departments in hospitals conduct prostate cancer screening in subjects under 40 years of age undergoing intensive health check-up for commercial reasons, and speculate that some medical doctors provide tacit consent for this action. To understand the prevalence of PSA testing in young men, the authors examined the age distribution of workers who underwent the PSA test. Methods: The authors used the 2009 intensive health check-up data of male workers aged 30–65 years (n = 298) in a car-manufacturing company to investigate the status of prostate-cancer screening in young men. Multiple comparison was conducted by Tukey's method when the analysis of variance revealed significant difference. Results: According to the frequency distribution of age, 15.8% of the subjects were under 40 years of age. The mean PSA value increased with age, ranging from 1.0 ng/mL in subjects in their 30s’, to 2.0 ng/mL in subjects in their 60s’. The mean PSA level in subjects in their 60s’ was significantly higher than that in subjects in their 30s’ and 40s’. The percentage of subjects with serum PSA levels of 4 ng/mL or higher in subjects in their 30s’, 40s’, 50s’ and 60s’ were 2.1% (1/47), 1.6% (2/125), 4.4% (5/114) and 8.3% (1/12), respectively. Conclusions: One-sixth of male workers attending the health check-up program were under 40 years of age. According to the criteria of the Japanese Urological Association, this examination program included younger subjects who were not candidates for PSA screening.  相似文献   

16.
The European green crab (Carcinus maenas) is a newly invasive species in Newfoundland, where it has likely been present for ≤15 years. The green crab has been found in stomach contents of American lobster (Homarus americanus) in New England and Nova Scotia, Canada, but predation on this species has not yet been quantified in Newfoundland. We conducted feeding experiments to determine whether lobsters from Newfoundland were as likely as those from Nova Scotia (which have coexisted with green crabs for >60 years) to recognize and prey upon this new species. We also performed experiments to determine whether green crabs reach a size refuge from predation and whether factors including starvation, availability of alternate food sources, or habitat complexity would influence the probability of lobster attacking or feeding on green crabs. In our trials, lobster origin had no significant effect on crab predation; lobsters, irrespective of origin, were more likely to consume small (<40 mm carapace width [CW]) and medium (40–65 mm CW) crabs than larger (>65 mm CW) ones. Nevertheless, even small lobsters (73–76 mm carapace length, 300 g) were able to kill and consume the largest green crabs (78 mm CW, 100 g). Green crabs were less likely to be attacked or eaten when an alternative food source was present, suggesting that the lobsters were preying on the crabs, rather than simply killing them in a dispute over territory. The addition of a shelter provided a refuge for the green crabs; however, the crabs were only able to avoid being injured or eaten if this shelter was structurally complex. The green crab is slowly spreading westward around the island of Newfoundland, and so its long‐term effects, interactions with other organisms, and contribution to the diet of Newfoundland lobsters remain to be seen.  相似文献   

17.
The TOMM40‐APOE variants are known for their strong, antagonistic associations with Alzheimer's disease and body weight. While a stronger role of the APOE than TOMM40 variants in Alzheimer's disease was suggested, comparative contribution of the TOMM40‐APOE variants in the regulation of body weight remains elusive. We examined additive effects of rs2075650 and rs157580 TOMM40 variants and rs429358 and rs7412 APOE variants coding the ε2/ε3/ε4 polymorphism on body mass index (BMI) in age‐aggregated and age‐stratified cohort‐specific and cohort‐pooled analysis of 27,863 Caucasians aged 20–100 years from seven longitudinal studies. Minor alleles of rs2075650, rs429358, and rs7412 were individually associated with BMI (β = ?1.29, p = 3.97 × 10?9; β = ?1.38, p = 2.78 × 10?10; and β = 0.58, p = 3.04 × 10?2, respectively). Conditional analysis with rs2075650 and rs429358 identified independent BMI‐lowering associations for minor alleles (β = ?0.63, p = 3.99 × 10?2 and β = ?0.94, p = 2.17 × 10?3, respectively). Polygenic mega‐analysis identified additive effects of the rs2075650 and rs429358 heterozygotes (β = ?1.68, p = 3.00 × 10?9), and the strongest BMI‐lowering association for the rs2075650 heterozygous and rs429358 minor allele homozygous carriers (β = ?4.11, p = 2.78 × 10?3). Conditional analysis with four polymorphisms identified independent BMI‐lowering (rs2075650, rs157580, and rs429358) and BMI‐increasing (rs7412) associations of heterozygous genotypes with BMI. Age‐stratified conditional analysis revealed well‐powered support for a differential and independent association of the rs429358 heterozygote with BMI in younger and older individuals, β = 0.58, 95% confidence interval (CI) = ?1.18, 2.35, p = 5.18 × 10?1 for 3,068 individuals aged ≤30 years and β = ?4.28, CI = ?5.65, ?2.92, p = 7.71 × 10?10 for 6,052 individuals aged >80 years. TOMM40 and APOE variants are independently and additively associated with BMI. The APOE ε4‐coding rs429358 polymorphism is associated with BMI in older individuals but not in younger individuals.  相似文献   

18.
A selection of multi‐stemmed, drought‐tolerant mallee eucalypts, planted in belt form and integrated with crops in dryland agricultural areas of Australia, may be able to produce biomass as a commercially attractive feedstock for biofuel production. This study aimed to determine if small (40–50 cm high) bunds along mallee belts could trap otherwise underutilized surface water runoff within paddocks, thereby increasing water available to the mallee trees and their growth rates. An experiment was established in 5 year‐old Eucalyptus polybractea (RT Baker) mallee belts near the town of Narrogin in the central wheatbelt area of Western Australia. Bunds led to significant (12%) increases in biomass accumulation after about 2 years and 35% increases at around 3 years. Bunds also led to significant increases in predawn leaf water potential and significant decreases in soil water deficit within 12 months, which persisted for the remainder of the 39 month trial. We suggest that the increase in biomass accumulation was largely due to increased water availability, but that increased nutrient supply from run‐on and trapping of organic residues may have also had some effect on bunded plots, despite our attempts to mitigate this effect by experimentally adding nutrients to all treatments. Results show that installing bunds along mallee belts would be a cost‐effective investment at sites where within‐paddock runoff is likely (i.e. gently sloping and with a loamy sand or heavier soil texture). Installation costs should be offset by improved biomass production within a few years and ongoing improvements in growth over the long term.  相似文献   

19.
BackgroundThe prevalence of nonalcoholic fatty liver disease (NAFLD) in Saudi Arabia is predicted to exceed 30% by 2030. NAFLD leads to liver fibrosis, thus increasing morbidity and health care burden. Obesity and diabetes have been strongly associated with NAFLD in different cities in Saudi Arabia.ObjectivesTherefore, we aim to determine the prevalence rate of NAFLD and specific risk factors for NAFLD among patients of tertiary care hospital of Taif city.Material and methodsWe retrospectively analyzed the medical records of patients for two years, between Feb 2017 and Feb 2019, (n = 100) referred to the hepatology clinic at King Abdulaziz Specialist Hospital in Taif. The diagnosis of NAFLD was based on the radiology report for patients who were aged >20 years old. Other parameters including fasting blood glucose (FBG), platelets count, alanine transaminase (ALT), aspartate transaminase (AST) and total bilirubin were statistically analyzed.ResultsWe found that 40% (P < 0.05) of all patients had NAFLD. The results revealed that a significantly high number of patients with NAFLD have high FBG levels (75%, P < 0.0001) and total bilirubin (P < 0.05). Meanwhile, platelet count was significantly reduced in patients with NAFLD (P < 0.05).ConclusionNAFLD can be a serious health problem in the Taif region. In addition, high FBG is a significant specific risk factor for NAFLD. Health care providers should pay more attention to limiting the prevalence of NAFLD and its risk factors.  相似文献   

20.
This study was conducted over a period of 20 years, to assess the problems involved in developing subcultures over a very long period, of oil palm (Elaeis guineensis Jacq.) somatic embryos which were maintained in vitro on a Murashige and Skoog mineral-based culture medium, without growth regulators. Analysis of the proliferation rate of the embryogenic cultures, along with the survivability of the regenerated plantlets after their transfer into soil and of the flowering of the derived adult palms has been conducted for cultures maintained in vitro during 1 to 20 years. From the ninth year of maintenance, the tissue quality of the somatic embryos gradually began to decline. However, after more than 20 years, 30% of the 20 clones tested still continued to proliferate satisfactorily on the same maintenance medium, keeping their multiplication potential intact. Even though a depressive effect of the age of the lines has been observed on the survival capacity of plants under natural conditions, it is noteworthy that among the clones originating from 20-year-old cultures only eight of them (40%) have exhibited the “mantled” floral abnormality. Different hypotheses concerning the origin of the disruptions observed on the in vitro cultures, plantlets and adult palms that occur over a very long period of in vitro conservation are discussed.  相似文献   

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