جستجوی مقالات مرتبط با کلیدواژه "longevity" در نشریات گروه "زیست شناسی"

The naked mole rat (Heterocephalus glaber) displays exceptional longevity, with a maximum lifespan exceeding 30 years. This is the longest reported lifespan for a rodent species and is especially striking considering the small body mass of the naked mole rat. In comparison, a similarly sized house mouse has a maximum lifespan of 4 years. In addition to their longevity, naked mole rats show an unusual resistance to cancer. Multi-year observations of large naked mole-rat colonies did not detect a single incidence of cancer. Here we identify a mechanism responsible for the naked mole rat's cancer resistance. We found that naked mole-rat fibroblasts secrete extremely high-molecular-mass hyaluronan (HA), which is over five times larger than human or mouse HA. This high-molecular-mass HA accumulates abundantly in naked mole-rat tissues owing to the decreased activity of HA-degrading enzymes and a unique sequence of hyaluronan synthase 2 (HAS2). Furthermore, the naked mole-rat cells are more sensitive to HA signaling, as they have a higher affinity to HA compared with mouse or human cells. Perturbation of the signaling pathways sufficient for malignant transformation of mouse fibroblasts fails to transform naked mole-rat cells. However, once high-molecular-mass HA is removed by either knocking down HAS2 or overexpressing the HA-degrading enzyme, HYAL2, naked mole-rat cells become susceptible to malignant transformation and readily form tumours in mice. We speculate that naked mole rats have evolved a higher concentration of HA in the skin to provide skin elasticity needed for life in underground tunnels. This trait may have then been co-opted to provide cancer resistance and longevity to this species.

It is very important to increase the life of flowers in cut flowers, which are perishable products and have a short life. By using different compounds and materials, the lifespan of cut flowers can be increased. The factorial experiment was conducted in a completely randomized design with four replications including 64 pots in Mashhad. Peppermint essential oil was the first factor in four levels (0, 100, 200 and 300 mg/l) and citric acid was the second factor in four levels (0, 100, 200 and 300 mg/l). To evaluate the shelf life of cut flowers based on the day, the time interval from harvest to when the number of wilted florets were more than open florets was considered as the end of flowering life. The results showed that peppermint essential oil on flower life was significant at 5% probability level and the effect of citric acid on number of opened florets, florence diameter, florence diameter, wilting percentage, stem fresh weight and flower longevity at 1% probability level Significant as well as the interaction of experimental treatments on the number of open florets, florence shedding and floreter diameter at 5% probability level and the percentage of wilting percentage, stem fresh weight and longevity at 1% probability level were significant. The highest number of open florets (4.62), floreter diameter (21.71 mm), fresh weight (75.82 g), flower longevity (7.88 days) related to 300 mg/l treatment Peppermint essential oil was 200 mg / l citric acid. In general, the use of peppermint essential oil and citric acid in different concentrations compared to the control increased flower life, fresh weight, number of open florets and diameter of florets as well as reduced florence and wilting percentage of sage.

Edible coatings have been used to preserve, improve the quality and increase longevity of fruits and vegetables. The aim of this study was to investigate the effect of two types of edible coatings on based natural gum on qualitative attributes and storage life of grape cv. Hosseini as a factorial experiment and completely randomized design. Fruits were immersed in Arabic gum (0, 5, 10 and 15 concentrations) and Almond gum (0, 3, 3.5 and 4 concentrations) in tree sampling times (at harvvest, 15, 30 and 45 day).  All treated fruits were stored in a cold storage in 1±0.5 °C and 95% RH for 45 days. Every 15 days, the percentage of weight loss, firmness, ripening index (TSS/TA), total phenol, vitamin C, amount of photosynthetic pigments, total carbohydrate and antioxidant activity of the skin and flesh of berries were measured. The results of the present study showed that coated samples had lower weight loss and better firmness than uncoated samples. Also, coated fruits could be able to preserve vitamin C, total phenol, pigments and antioxidant activity of the skin and flesh of berry better and the amount of TSS/TA and total carbohydrates increased lower than control samples. It is concluted that the concentrations of %5 Arabic gum and %3.5 Almond gum had a significant defference in most of the parameters with other concentrations and the qualitative and sensual attributes of berry could be preserved better than other treatments and extended fruit storage life.

This study for Effect of EC Irrigation Water on Quality and Quantity of Rosa cv. Dolce Vita in Hydroponic Culture, in a completely randomized design experiment with 4 treatments, 3 replication, were conducted. Pot without irrigation with sodium chloride was used as control. To perform the experiment, cuttings of roses were prepared and cultured in 5-kg pots containing 70% cocopeat and 30% perlite. Irrigation was carried out twice a day at the beginning of the experiment with saline water and after the third day irrigation was done by applying salinity treatments in all treatments equally (with equal volume ratio). Quantitative and qualitative traits of plant such as fresh and dry weight of shoot, flower number, bud diameter, stem diameter, petal length, anthocyanin of petals, total chlorophyll of leaf, potassium and calcium content and longevity of rose on plant were evaluated. The results showed that application of all salinity levels due to sodium chloride salt reduced all evaluated traits compared to control. Also, analysis of variance table showed that the effect of treatment on all traits was statistically significant at 1% level and there was a positive and significant correlation between all traits at 1 and 5% level

The length of vase life is on of the most imoirtant factors foe quality of cut flowers. In the world many attempts have been taken to increase the vase-life of cut flowers by using different methods and materials. In this research, the effect of applying citric acid and malic acid each on with 3 concentration 2, 4 and 6 mM at preharvest stage on vase-life of rose was investigated. The factorial experiment was carried out as a randomized complete blocks design with 7 treatment and 3 replications. Durind the experiment traits such as relative fresh weight, height of plant, anthocyanins levels in petals, total chlorophyll of leaf, protein, activity of PAL and SOD enzyme and flower longevity on plant were evaluated. The results showed that usage of malic acid and citric acid cause improvement in traits of evaluated vs. control and The best results in all of the parameters observed in malic acid (6 mM).

Gerbera and Polyanthus are two of very important in cut flowers global production. In this research,experiment on completely randomized block design with 12 treatment and 3 replications was carried out. The aim of this study was to investigate the effect of postharvest application of ethanol and sucrose on keeping quality and vase life of cut gerbera and polyanthus flowers. The cut flowers were harvested and after recut under water, were kept in preservative solutions containing sucrose 4%, ethanol 2.5% and combine sucrose and ethanol. The results showed that application of ethanol and sucrose increase vase life in cut gerbera and polyanthus flowers. Combination ethanol with sucrose increased significantly keeping quality and vase life flowers over control. Also, keeping gerbera and polyanthus cut flowers alone in preservative solution have better postharvest life than keeping them together.

Study the effect of silisum spray in rosa flowers, experiment in a completely randomized design with 7 treatments included 3 replications and each replications with 3 pots were conducted. Treatments include sodium silicate, calcium silicate and potassium silicate, each with two levels of 25 and 50 ppm and the pot was considered as control without spraying. Pots, two times in the first week of spraying was conducted on the same basis and traits such as petals antocyanin, leaf total chlorophyll, phenyl alanin amonialyase activity and flowers longevity on plant were evaluated. The results showed that the treatment of CaSi 50 ppm had the greatest effect on correction the traits. Result at 1% statistical level had significant effect.

For study the effect of silisum spray in rosa flowers, experiment in a completely randomized design with 7 treatments included 3 replications and each replications with 3 pots were conducted. Treatments include sodium silicate, calcium silicate and potassium silicate, each with two levels of 25 and 50 ppm and the pot was considered as control without spraying. Pots, two times in the first week of spraying was conducted on the same basis. Morphological traits such as flower fresh weight, flower dry weight, flower diameter, stem diameter and flowers stem lenght were evaluated. The results showed that the treatment of CaSi 50 ppm had the greatest effect on correction the traits. Result at 1% statistical level had significant effect.

Polyamines of aliphatic amine groups are involved in a wide range of biological processes, Polyamines as plant growth regulators in a wide range of developmental processes, including cell division, embryogenesis, morphogenesis, flowering, fruit ripening, root development, delay aging, stable membranes, collection of active radicals and stress tolerance different participate, Putrescine (put), spermine (spm) and spermidine (spd) is the most common polyamines. The study to evaluate the effect of putrescine, spermidine spermine and on some physiological characteristics, morphological and biochemical number of black baccara roses was carried out. Rose Rosa hybrida plant with the scientific name of the Rosaceae family (Rosaceae) is. There are about 107 genera and 3,100 species in this family. Rose Rose family, along with 24 other families are in order. About 70 genera have been identified Rose as edible and medicinal plants. Apple trees, pear, quince, peaches, almonds, cherries and aspiration of food, Cotoneaster and a variety of roses ornamental use. Rose genus of about 140 species, more than 20,000 varieties are the result of hybridization and selection of new species. 95 species of roses Asian origin, originating in North America and the rest of Europe 18 Africa were derived. This study randomized with 7 treatments including spm, spd and put in a concentration of 100 ppm 50 and distilled water as a control with three replicates each of three experimental unit is composed of a total of 63 pots of roses And evaluated traits include flower diameter, stem height, cell membrane stability index, anthocyanins, chlorophyll, proline, protein and plant flower life is over. Duncan's multiple range test results of analysis of variance showed that spermine ppm 100 greatest impact in improving the morphological, physiological, and the results were significant at 1%.

In this research age structure in populations of two anuran species: a frog R. ridibunda and a toad Bufo viridis was studied using skeletochronological method. To perform this task، 20 individuals of the frog (13 male and 7 female) and 22 individuals of the toad (13 male and 9 female) were collected during different seasons of year from their natural habitat in Khorramabad and transferred to the laboratory where they were killed and their femur bones were dissected out from their legs. The bones were then decalcified، dehydrated، cleared، embedded، cut، stained and observed under a light microscope. The age was estimated for individuals by counting the number of lines of arrested growth (LAG) in cross-sections taken from femurs. On the basis of observations، the age range was 3-11 and 1-8 for R. ridibunda and B. viridis، respectively. Moreover، to find any relation between snout-to-vent length (SVL) and age، we analyzed the data using statistical methods. Results obtained from this analysis indicated that there is no positive relation between these two characters neither in R. ridibunda nor in B. viridis. This is true for both males and females. According to these finding we can come to the conclusion that these species do not show a significant growth after puberty.