Intracellular Distribution of Heat Shock Proteins in Pigeon Pea (Cajanus cajan)

The proteins synthesized In response to higher temperature In pigeon pea (Cajanus cajan) plants have been studied with respect to their Intracellular localization using root tissue. The heat shock proteins (hsps) of 18, 20, 22 and 24 kD were found to be associated with mitochondrial and membrane fractions, while the 60, 70 and 81 kD hsps were found In the soluble fraction. No evidence for the presence of hsps among the proteins synthesized in organello by isolated mitochondria could be obtained. Low molecular weight hsps (18, 20, 22 and 24 kD) were found associated with mitochondria Isolated from the heat shocked tissue suggesting that these hsps may have been transported post-translationally into mitochondria.     

Growth and metabolic responses of contrasting chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) genotypes to chilling stress at reproductive phase

Chilling stress (<10°C) at reproductive phase of chickpea results in abortion of flowers and pods leading to poor yield. The metabolic causes associated with cold sensitivity of chickpea are not well understood. Hence, in the present study, we evaluated four chickpea genotypes (ICC 16348, ICC 16349, PBG1 and GPF2) having contrasting cold sensitivity for their reproductive growth and metabolism subjected to cold stress (average day temperature: 17.6°C; average night temperature: 4.9°C). Genotypes ICC 16348 and ICC 16349 showed flowering and set pods, while PBG1 and GPF2 failed to do so during the stress conditions indicating the former to be cold tolerant. The stress injury in the leaves such as increase in electrolyte leakage, decrease in chlorophyll content and relative leaf water content was significantly less in ICC 16348 and ICC 16349 genotypes. The analysis of carbohydrates indicated total sugars and starch to be present in greater content in ICC 16348 and ICC 16349 relative to PBG1 and GPF2 genotypes. The enzymes related to carbohydrate metabolism such as β-amylase, invertase and sucrose synthase showed significantly higher activity in the leaves of ICC 16348 and ICC 16349 compared to the other two genotypes. PBG1 and GPF2 genotypes experienced greater oxidative stress measured as malondialdehyde and hydrogen peroxide. ICCV 16348 and ICC 16349 possessed significantly higher levels of enzymatic (superoxide dismutase, catalase, ascorbate peroxidase) and non-enzymatic antioxidants (proline and ascorbic acid) relative to PBG1 and GPF2. Particularly, proline and ascorbic acid were markedly higher in cold-tolerant genotypes compared to the sensitive ones suggesting their deciding role in governing the cold tolerance.     

A mathematical model of the effects of Co2 on stomatal dynamics

We extend a previous model of stomatal dynamics (Delwiche & Cooke 1977) which accounted for hydraulic feedback effects but which omitted CO₂ feedback effects. The present work includes both feedback loops in a model featuring the CO₂ chemistry of the guard cell. The model consists of three first order non-linear differential equations which are treated by numerical integration.     

Does dexamethasone enhance control of acute cisplatin induced emesis by ondansetron?

OBJECTIVE--To determine the contribution of dexamethasone to the efficacy of the 5-hydroxytryptamine antagonist ondansetron in control of cisplatin induced nausea and vomiting. DESIGN--Randomised double blind crossover study. SETTING--Two cancer centres in teaching hospitals, one in the United Kingdom and the other in Germany. SUBJECTS--100 patients (53 men and 47 women) new to cisplatin chemotherapy, 84 of whom completed two consecutive courses of chemotherapy. INTERVENTIONS--Patients were given intravenous dexamethasone (20 mg) or physiological saline with intravenous ondansetron 8 mg before cisplatin, then ondansetron 1 mg/h for 24 hours. Oral ondansetron 8 mg was taken three times daily on days 2-6. MAIN OUTCOME MEASURES--Incidence of complete or major control of emesis (0-2 episodes in the 24 hours after chemotherapy). RESULTS--Complete or major control was obtained in 49 out of 71 (69%) of patients after receiving ondansetron plus dexamethasone compared with 40 out of 71 (56%) when they were given ondansetron alone (p = 0.012). This effect was most pronounced in the first 12 hours after chemotherapy. Patients receiving the combination also had significantly less nausea. Of the 53 patients who expressed a preference, 38 (72%) preferred the combination treatment (p = 0.002) to ondansetron alone. The effect of ondansetron on delayed emesis was less pronounced. CONCLUSIONS--Dexamethasone makes a significant contribution to the efficacy of ondansetron in the control of acute platinum induced emesis.