Root dynamics and drought stress management in plants — Overview

Drought is a predominant factor responsible for yield reduction throughout the world. The current scenario of climate change and global warming are further causing frequent and severe droughts, which emphasizes the need to understand the response of plants to drought stress. Hence, it is imperative to develop a system wherein water utilization is more efficient in agriculture. In this context, the plant root system which is in close association with soil assumes greater importance and they play an important role in plant growth and development by exploiting soil water and nutrients. Root traits such as root diameter, length, specific area, angle, length and density are considered useful traits for improving plant growth under drought conditions. This review on root dynamics under drought stress presented here provides readers with the latest information on root system architecture, genetics, physiology and molecular responses of roots under drought stress.

Are our donors safe?

Blood is defined as a 'drug' under the Drugs and Cosmetics Act. The Standard of drugs is laid down in the Indian Pharmacopoeia. The first step towards blood safety is to encourage blood donations, which are voluntary, non-remunerated and obtained from low-risk and regular donors. A regular donor is one who donates blood two to three times a year and continues to donate at least once a year. Over the last 8 years, the Drug Control Authority has been taken up many steps to improve the quality of blood in circulation. As a result, blood centres are now equipped with minimum modern tests for making blood safer. The inspectors are also emphasising the need to employ uniform procedures for donor selection, donor deferral, validation of equipment, and so on. Over the last 5 years, quality control of diagnostic kits prior to their registration and marketing have been streamlined to ensure that blood centres use highly sensitive kits while testing for blood transmissible diseases. Therefore, current methods of donor screening and testing of donated blood have led to a remarkable decrease in the incidence of transfusion-transmitted infection and a blood supply that is very safe. The greatest threat to blood safety is donation by seronegative individuals during the infectious window period when they are undergoing seroconversion and infection cannot be detected by available laboratory tests. Look-backs is the process whereby blood collection facilities attempt to indentify prior recipients of blood donated by individuals who subsequently test positive TTD. This alone can assure safety.

Glanzmann's thrombasthenia.

During January 1981 to June 1991, 20 patients from 16 unrelated families were detected to have Glanzmann's thrombasthenia (GT). Twelve families (75%) had history of consanguinity, with 6 first cousins and 3 uncle-niece marriages; of these 7 were Muslims, 6 Hindus and 3 Christians. There were 12 girls and 8 boys; the mean age at diagnosis was 7.05 +/- 6.03 yr (range 1 day-22 yr). All cases had initial bleeding prior to the age of 5 yr with the mean age at the initial episode of bleeding being 2.21 +/- 1.34 yr (range 1 day-5 yr). Common pattern of bleeding included epistaxis, gingival bleeding, post-traumatic bruises, menorrhagia, gastrointestinal (2 cases), post-operative (2 cases) and spontaneous bleeding (2 cases). No patient showed hemarthrosis, intracranial bleeding or hemoptysis. Menorrhagia was a serious problem necessitating repeated transfusions and hormonal therapy. Twelve cases (60%) required 1-120 units of blood transfusions while five received platelet concentrates.

A simple technique for hemoglobin estimation to screen for anaemia.

Drabkins method has been modified enabling detection of anaemia in a large population. 132 samples of EDTA blood were subjected to hemoglobin estimation by (1) Direct Drabkin (DD) (2), Filter Drabkin (FD) and (3) Special Filter Drabkin (SFD). Hemoglobin estimations by DD and FD compared well on statistical analysis. SFD with a punch diameter of 10.6 to 10.7 mm compared well with DD and is ideal for screening anaemia in field studies.

Anti-nuclear antibody positivity in multi-transfused thalassemia major.

The frequency of anti-nuclear antibodies (ANA) was evaluated in multi-transfused patients of thalassemia major. Twelve out of 83 patients (14.5%) had positive ANA at titres of 1:80 or above. The results were compared with age and sex matched healthy controls who showed positive results in only 1 of 52 cases (1.9%; p less than 0.05). Antibody against double stranded DNA was absent. ANA positivity was found to correlate with higher age (p less than 0.01), more amount of blood transfused (p less than 0.01), splenectomy status (p less than 0.01), higher levels of serum ferritin (p less than 0.01) and presence of hepatitis B surface antigen (p less than 0.01) and antihepatitis C antibody (p less than 0.01).

Efficacy and safety of 1-2, dimethyl-3-hydroxypyrid-4-one (L1) as an oral iron chelator in patients of beta thalassaemia major with iron overload.

Twenty-four patients with beta thalassaemia major, aged 8-22 years (mean 15.3 +/- 8.1) were given 1-2, dimethyl-3-hydroxypyrid-4-one (L1) orally for a period of three months. The drug was given in the dose of 25 mg/Kg/day for the first week and gradually increased to 100 mg/Kg/day which was continued until 3 months. The mean urinary iron excretion was 5.73 +/- 3.648 mg/day on 25 mg/Kg/day of L1; 15.2 +/- 11.225 mg/day on 50 mg/Kg/day; 24.2 +/- 12.69 mg/day on 75 mg/Kg/day and 36.3 +/- 19.4 mg/day on 100 mg/Kg/day of L1. Serum ferritin estimated by ELISA before and 3 months after L1 therapy in 21 patients showed significant drop in levels, the mean drop being 964.3 +/- 844.4 (P less than 0.001). The only side-effects noted were transient gastrointestinal symptoms in 5 patients and skeletomuscular pain in 3 patients. Both these groups of symptoms were of transient nature. The efficacy of L1 appears to be excellent and equivalent to the standard iron chelation therapy available at present i.e. desferrioxamine. It appears to be free of major toxicity. L1 is also a specific chelator for iron as it does not deplete trace metals. L1 appears to be a cheap and effective oral alternative to desferrioxamine for treating iron overloading.