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PubMed2002

Ethylene biosynthesis and action in tomato: a model for climacteric fruit ripening.

Elucidating the mechanisms involved in ripening of climacteric fruit and the role that ethylene plays in the process are key to understanding fruit production and quality. In this review, which is based largely on research in tomato, particular attention is paid to the role of specific isoforms of ACC synthase and ACC oxidase in controlling ethylene synthesis during the initiation and subsequent autocatalytic phase of ethylene production during ripening. Recent information on the structure and role of six different putative ethylene receptors in tomato is discussed, including evidence supporting the receptor inhibition model for ripening, possible differences in histidine kinase activity between receptors, and the importance of receptor LeETR4 in ripening. A number of ethylene-regulated ripening-related genes are discussed, including those involved in ethylene synthesis, fruit texture, and aroma volatile production, as well as experiments designed to elucidate the ethylene signalling pathway from receptor through intermediate components similar to those found in Arabidopsis, leading to transcription factors predicted to control the expression of ethylene-regulated genes.

Amino Acid Oxidoreductases↗
PubMed2003

Isolation and promoter analysis of two genes encoding different endo-beta-1,4-glucanases in the non-climacteric strawberry.

Two endo-beta-1,4-glucanase (EGase; EC 3.2.1.4.) genes, highly expressed during ripening of the non-climacteric strawberries (Fragariaxananassa Duch. cv. Chandler), were isolated. Serial promoter deletions of both genes (i.e. FaEG1 and FaEG3) fused to GUS were transiently assayed in strawberry fruits by using a technique recently developed in this laboratory. Although differences were observed with the short fragments, GUS activity became comparable with the largest fragments of both promoters. The apparently similar strength of the two largest promoter fragments was in contrast with previous results of Northern analyses which demonstrated different transcripts amounts for the two genes. The inclusion of the 3' flanking region of both genes in the transient assays showed that, in the case of FaEG3, the 3' region had a down-regulating effect on the expression of GUS, and this might account for the lower amount of FaEG3 mRNA usually observed in ripe fruits compared to that of FaEG1. Downstream instability elements might be involved in such down-regulation.

Cellulase↗
PubMed2003

Carbon dioxide action on ethylene biosynthesis of preclimacteric and climacteric pear fruit.

Ethylene production in pear fruit was studied at 2 degrees C. Several observations showed that the inhibiting effect of CO2 on ethylene production did not operate only via the binding site of the ethylene binding protein. Ethylene production of freshly harvested pears was stimulated by 1-methylcyclopropene (1-MCP), but unaffected or inhibited by CO2 which points to different action sites for both molecules. In climacteric pears, where ethylene production was strongly inhibited by 1-MCP, a range of applied CO2 partial pressures was able to inhibit ethylene production further, to an extent similar to untreated pears. In the case of pears that had been stored for a period of 25 weeks, CO2 only had a clear effect after 1-MCP pretreatment. Respiration measurements showed that the effect of CO2 on ethylene production did not operate via an effect on respiration. Ethylene production models based on measurements of whole pears were used to study CO2 effects. Kinetic parameters derived from the models point to the conversion from ACC to ethylene by ACC oxidase as a possible action site for CO2 inhibition.

Amino Acid Oxidoreductases↗
PubMed1974

Similarities between the Actions of Ethylene and Cyanide in Initiating the Climacteric and Ripening of Avocados.

A continuous exposure of intact avocados (Persea americana) to 400 mul/l of cyanide results in a rapid increase in the rate of respiration, followed by a rise in ethylene production, and eventual ripening. The pattern of changes in the glycolytic intermediates glucose 6-phosphate, fructose diphosphate, 3-phosphoglyceric acid, and phosphoenolpyruvate during the rapid rise in respiration in both ethylene and cyanide-treated fruits is similar to that found in fruits made anaerobic where a 2.3- to 3-fold increase in the rate of glycolysis is observed. It is suggested that both during the climacteric and in response to cyanide, glycolysis is enhanced. It is proposed that cyanide implements the diversion of electrons to the cyanide-resistant electron path through structural alterations which are independent of the simultaneous inhibition of cytochrome oxidase.

Journal Article↗
PubMed1990

Short-Term Effects of gamma-Irradiation on 1-Aminocyclopropane-1-Carboxylic Acid Metabolism in Early Climacteric Cherry Tomatoes : Comparison with Wounding.

gamma-Irradiation of early climacteric (breaker) cherry tomatoes (Lycopersicon pimpinellifollium L.) caused a sharp burst in ethylene production during the first hour. The extent of ethylene production was dose dependent and was maximum at about 3 kilograys. The content of 1-aminocyclopropane-1-carboxylic acid (ACC), followed the same evolution as ethylene production, while malonyl ACC increased steadily with time in irradiated fruits. The burst in ethylene production was accompanied by a sharp stimulation of ACC synthase activity which began 15 minutes after irradiation. The stimulation was completely prevented by cycloheximide, but not by actinomycin d or cordycepin. In contrast with irradiation, mechanical wounding continuously stimulated ethylene production over several hours. gamma-Irradiation and cordycepin applied to wounded tissues both caused the cessation of this continuous increase, but the initial burst was still persisting. These data suggest that gamma-irradiation, like wounding, stimulates the translation of preexisting mRNAs. It also reduces, at least temporarily, the subsequent transcription-dependent stimulation of ethylene production. gamma-Irradiation greatly inhibited the activity of ethylene-forming enzyme at doses higher than 1 kilogray. Such sensitivity is in accordance with a highly integrated membranebound enzyme.

Journal Article↗
PubMed1990

Role of sucrose phosphate synthase in sucrose biosynthesis in ripening bananas and its relationship to the respiratory climacteric.

During ripening of bananas (Musa spp. [AAA group, Cavendish subgroup]), there is a massive conversion of starch to sucrose. Also during ripening there is a rise in respiration known as the respiratory climacteric. In this study changes in carbohydrate content, activities of starch and sucrose metabolizing enzymes, and respiration were measured to assess their potential interrelationships. Sucrose phosphate synthase activity increased dramatically during the first 4 days after initiation of ripening by ethylene treatment. Starch concentration decreased and sucrose concentration increased during this time period. Developmental changes in sucrose phosphate synthase activity were measured with limiting substrate (plus Pi) and saturating substrate concentrations. Activities were not parallel under the two assay conditions, providing tentative evidence that kinetically different forms of the enzyme may exist at different stages of ripening. Sucrose accumulation rate was most highly correlated with sucrose phosphate synthase activity assayed with limiting substrate concentrations (plus Pi). The cumulative amount of CO(2) respired during ripening was positively correlated with sugar accumulation (R(2) = 0.97). From this linear regression it was calculated that a constant 0.605 millimoles of CO(2) was evolved per mole of sucrose formed throughout ripening. Using this quantity, the percentage of the total respiratory ATP produced which was required for the conversion of starch to sucrose was calculated assuming different models for carbon export from the amyloplast. The results suggest that sucrose biosynthesis during ripening constitutes a significant sink for respiratory ATP.

Journal Article↗
PubMed1998

Quantitative bone ultrasonometry in climacteric women.

Quantitative bone ultrasound (QUS) measurement is an emerging technique in the assessment of osteoporosis risk. In this study, bone mineral density (BMD) (mg/cm2) of lumbar vertebrae, neck, Ward's triangle and trochanter were measured by DXA and the phalanx amplitude dependent speed of sound (AD-SOS) was measured by QUS in climacteric (n = 1025) women. The relationship between AD-SOS and BMD values at different skeletal sites was significant, even if the analysis showed poor correlation coefficients. These data seem to indicate that QUS can detect bone characteristics in addition to density. The AD-SOS was higher in premenopausal than in perimenopausal women. The AD-SOS further decreases in postmenopausal women without hormone replacement. The age at menopause is relevant for predicting the AD-SOS in the postmenopausal years. Conversely, the maintenance of a regular menstrual function is associated with higher AD-SOS. Thus, the early impairment and cessation of ovarian function can lead to an earlier and/or sharper decline in bone homeostasis that can be detected by QUS. In conclusion, AD-SOS is a valuable index in detecting menopausal bone loss, and could be used for the patient follow-up during menopausal transition and in therapeutic trials.

Journal Article↗
PubMedDate not supplied

[Climacteric: the corporeity as cradle of life experience].

Qualitative study of phenomenological approach, accomplished from women's testimony aged between 58 and 55, who had presented spontaneous menopause over the last 12 months or more. The results evidenced five thematic categories that were analyzed and interpreted under the light of Maurice Merleau-Ponty's philosophical theoretical referral. Among the categories that have emerged from the testimonies, the unveiled theme "Make yourself aware of the world through your body in space and time" will be presented with the objective of stimulating the reflection on existential aspects of experiencing this reproductive cycle phase and make considerations on the climacteric woman health care.

Female↗
PubMedDate not supplied

[The post menopausal climacteric woman with coronary artery disease: implications to quality of life].

PURPOSE: To analyse the quality of life of post menopausal women with coronary artery disease. METHODS: The population consisted of 100 women, divided into 2 groups. The first group made up of 50 women whose average age was 58 +/- 4,2 years with > stable coronary artery disease (CAD) proved by angiography undergoing treatment at The Heart Institute (InCor) - University of São Paulo Medical School, Brazil (CAD group). This group was compared with 50 women (55.1 +/- 5.4 years old) without clinical evidence of coronary artery disease (control group) from a primary health care center, Centro de Saúde Escola Geraldo de Paula Souza, São Paulo - FSP- USP. The quality of life was assessed by a structured interview and by Medical outcomes study 36-item short-form health survey (SF-36) validated to the Brazilian population. RESULTS: They were homogenous regarding age of the last menstruation period: 49 +/- 3.9 years old in CAD and 49.2 +/- 3 years old in controls. The groups were also similar in education level, marital status (64% of CAD and 45% of controls were married; and 18% of CAD and 24% of controls were widowhood). The active working status was more frequent in controls than in CAD (52% vs. 14%; p= 0.0001). Both groups showed similar perceptions in their sexual experience. The evaluation of quality of life by SF-36 showed better scores for the control group in: physical functioning (84 vs. 50.5), role physical (84 vs. 45,5), general health (87.2 vs. 59.1), vitality (69.7 vs. 51,4), p<0.0001; and total score of mental components (70.4 vs. 58.6), p = 0.028. CONCLUSION: Coronary artery disease alters the quality of life of climacteric women by limiting the physical capacity to perform ordinary daily activities and by intensifying emotional conflicts usually present in this phase of life.

Case-Control Studies↗
PubMedDate not supplied

Managing the climacteric.

HRT taken for a sufficient duration may reduce the occurrence of osteoporosis and of cardiovascular disease by up to 50% and possibly also reduce incidence and lessen severity of Alzheimer's disease. Nevertheless, it is often only prescribed when women request it to relieve climacteric symptoms. Furthermore, many physicians prescribe it for only limited periods of time and few are willing to prescribe it to women in their sixties. As with any long-term prevention strategy, the uptake of HRT is much lower than the prescription rate, since the medication is often abandoned due to side effects or due to lack of motivation. But HRT is often abandoned also due to fear of cancer. While physicians may be aware of some beneficial effects of HRT, they often have no time to inform their patients of them. Alternatively, some of the beneficial effects such as cardioprotection or a reduced incidence of Alzheimer's may be less known. Likewise, HRT-related side effects or risks such as breast cancer or thromboembolic diseases should be discussed prior to HRT prescription. Women need to be informed about these potential risks, and this should be done by their physician. Surveys have shown that many women feel that they receive insufficient information from their physician. The quality of the relationship between physician and patient probably has a large influence on HRT acceptance, but very few studies have been conducted to assess specifically factors influencing the prescription and the continuation rate of HRT. Simple strategies may be among the most effective ones; these include listening to patients' fears, complaints and questions, and taking the time to answer them. The role of a practice nurse in such a setting may be also very important.

Attitude to Health↗
PubMed2000

[The efficacy of low estrogen transdermal therapy in climacteric symptoms management].

The aim of the study was to evaluate the efficacy and tolerability of low doses estrogen transdermal system treatment in management of climacteric symptoms. On the basis of performed researches it seems to be reasonable to start hormonal replacement therapy with the very low dosage of estrogen to achieve sufficient results and avoid side effects.

Administration, Cutaneous↗
PubMed2001

Comparison of biochemical markers of bone turnover and bone mineral density in different groups of climacteric women.

In the present study we evaluated plasma levels of two markers of bone turnover (osteocalcin (OC) and urinary pyridinium cross-links) in association with bone mineral density (BMI) in different groups of climacteric women. We have investigated 158 women in pre-, peri- and postmenopause. Blood and urine samples for assay of hormones and markers were collected and bone mineral density (BMD) was measured by DEXA densitometry in the distal tenth of the non-dominant forearm. There was a significant increase in mean absolute levels of both markers in perimenopause and women in natural and surgical menopause, with respect to women in premenopause. There was a significant correlation between OC and deoxypyridoline (DPYR) in peri- and postmenopause groups. In peri- and postmenopause groups, BMD was correlated with an increase in the biochemical markers of bone remodeling. In the present study, OC and DPYR were found to have good sensitivity for identifying perimenopausal women with pathological BMD. The present results reveal a positive and significant correlation between DPYR and OC, inversely proportional to BMD, during hormone replacement therapy. These markers therefore turn out to be sensitive not only for monitoring severe pathology of bone turnover, but also for monitoring slight physiological deficits in bone equilibrium beginning in perimenopause.

Adult↗
PubMed2002

[Prevalence of sexual dysfunction in climacteric women. Influence of menopause and hormone replace therapy].

BACKGROUND: Few trials have studied the prevalence of sexual dysfunction (SD) and related risk factors in postmenopausal women using the DSM-IV criteria. AIM: To evaluate the prevalence of SD in menopausal women and the impact of risk factors. PATIENTS AND METHODS: Five hundred thirty four healthy women, 40 to 64 years of age were interviewed using the Laumann test (DSM-IV). RESULTS: Mean age was 52.4 +/- 5.7 years. Eighty three percent were peri or postmenopausal, 23% used hormonal substitution therapy and 79.2% were sexually active. Among sexually active women, the prevalence of SD increased along with age, from 22.2% at the 40-44 years old range to 66.0% in the 60-64 years old group. Hormone users and healthy women had a low risk for SD (Odds ratio (OR): 0.1 IC: 0.0-0.1 and OR: 0.6 IC: 0.3-0.9, respectively). The risk increased in menopausal women (OR: 3.3 IC: 1.6-6.9), those older than 49 years (OR: 3.4 IC: 1.8-6.4), those subjected to hysterectomy (OR: 3.7 IC: 1.3-10.6) or those with an impotent sexual partner (OR: 3.2 IC: 1.2-8.6). CONCLUSIONS: There is a high prevalence of SD among climacteric women. Estrogens, either endogenous or exogenous, have a positive influence on sexuality.

Adult↗
PubMed1954

The climacteric.

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Animals↗