جستجوی مقالات مرتبط با کلیدواژه "glycogen" در نشریات گروه "گیاهپزشکی"

The large cabbage white, Pieris brassicae (L.), is a pest of Brassicaceae family which overwinters as a pupa on different host plants or other shelters. Little information is available on the physiological changes during overwintering of this pest and its cold tolerance. In the current study, the cryoprotectants were identified by LC/MS and their changes were examined by HPLC in specimens collected during the months of autumn and winter, as well as lab-reared pupae which treated one week at 27, 15, 10, 7, and 4 °C. The changes of glycogen content were investigated as the main source of cryoprotectants. Four compounds of trehalose, sorbitol, glucose, and inositol were identified and trehalose and sorbitol showed the highest increase in the winter months and these changes were accompanied by a significant decrease in the glycogen content. In lab-reared pupae treated in 7 and 4 °C, trehalose and sorbitol significantly increased. Therefore, it seems that trehalose and sorbitol, as the most important cryoprotectants, play a significant role in tolerating of low temperatures of winter and tolerating temperatures below 10 °C can induce the production of such compounds in this species.

In order to study the pollution potential of TiO2 nanoparticles (TiO2-NPs) on ecological health، this research was carried out on the cellular energy allocation (CEA) of Glyphodes pyloalis Walker exposed to TiO2-NPs. The newly ecdysed fifth instar larvae of G. pyloalis were treated with LC10، LC20، LC30، LC40 and LC50 concentrations of TiO2-NPs and the amount of energy available (Ea)، energy consumption (Ec) and cellular energy allocation were compared. The resulting calculated energy reserves (lipid، carbohydrate، glycogen and protein) showed that increasing the time of exposure، the total lipid and carbohydrate amounts significantly decreased، when the LC30، LC40 and LC50 concentrations were applied. The amounts of glycogen in the larvae treated with LC10، LC20 and LC30 concentrations of TiO2-NPs were increased، whereas the LC40 and LC50 concentrations led to decrease in the amount of glycogen. The significant reduction in the amount of total protein compared to the control and over all three days of treatment was observed for LC50 concentration of TiO2-NPs; however، the LC10 concentration lead to a significant increase of the total protein after three days. Ea decreased in a dose-response related manner and over all time points، but it significantly increased in treated larvae by LC10 and LC20 concentrations after two days. Ec increased as concentrations grew to LC30 and then started to decrease. The results showed that CEA was not affected by LC10 concentration، but significantly decreased when the concentration increased and at all time points probably as a cost to deal with TiO2-NPs detoxification. Therefore، it will be possible to use the CEA as an appropriate early biomarker for the impacts of TiO2-NPs.

Cabbage aphid، Brevicoryne brassicae (L.)، is an important pest of cabbage، especially ornamental cabbages، due to its voracity and population build-up on these plants in wintertime. The cryoprotectants of B. brassicae and their changes were investigated during the cold seasons. Adult aphids were collected monthly on ornamental cabbages from October 2008 through May 2009. The amount of sugars and polyols were measured by high performance liquid chromatography (HPLC) and the amount of glycogen was spectrophotometrically determined. The identified compounds were as follows: glucose، mannitol، myo-inositol and trehalose. Mannitol، myo-inositol and trehalose were significantly correlated with average temperature. The total amount of these compounds increased from the lowest amount (11. 90 ± 3. 07 µmol/g f. w.) in October to its highest (55. 8 ± 8. 83 µmol/g f. w.) in the coldest month، January. There appears that these three compounds، especially mannitol، play important roles in enhancing cold tolerance of B. brassicae during cold seasons. The amount of glycogen showed no significant differences during those months and varied from 4. 8 ± 0. 58 mg/g f. w. in October to 3. 3 ± 0. 98 mg/g f. w. in December. There was no significant correlation between glycogen and the cryoprotectants.

The beet armyworm, Spodoptera exigua (Hübner), is a highly polyphagus insect that feeds on many cultivated hosts and weeds. To understand how well this pest survives in cold temperature during winter, seasonal variation in the supercooling points (SCPs) were studied in field-collected and lab-reared samples. In this study, the beet armyworm overwintered as dark mature larvae in dried fallen leaves or on the soil surface. Their SCPs increased significantly (P<0.01) from -12°C in November to -6°C in March and these larvae could survive below their SCPs. However lab-reared ones could not survive below their SCPs. Supercooling points of different stages of lab-reared samples changed significantly (P<0.001) and it was lowest in eggs (-28°C). Trehalose, glucose, glycerol and sorbitol were identified as main cryoprotectants. Glycogen contents were significantly (P<0.01) decreased (more than 70%) in larvae collected in February and March rather than overwintering larvae collected in November and December. In different stages of lab-reared samples it changed significantly and was highest in pupae. So, it seems that overwintering larvae of beet armyworm are freeze tolerant and glycogen is a major reserve for overwintering during cold months.