Impact of High Night‐Time and High Daytime Temperature Stress on Winter Wheat

High temperature is a major environmental factor that limits wheat (Triticum aestivum L.) productivity. Climate models predict greater increases in night‐time temperature than in daytime temperature. The objective of this research was to compare the effects of high daytime and high night‐time temperatures during anthesis on physiological (chlorophyll fluorescence, chlorophyll concentration, leaf level photosynthesis, and membrane damage), biochemical (reactive oxygen species (ROS) concentration and antioxidant capacity in leaves), growth and yield traits of wheat genotypes. Winter wheat genotypes (Ventnor and Karl 92) were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of anthesis. Thereafter, plants were exposed to high night‐time (HN, 25/24 °C), high daytime (HD, 35/15 °C), high daytime and night‐time (HDN, 35/24 °C) or optimum temperatures for 7 days. Compared with optimum temperature, HN, HD and HDN increased ROS concentration and membrane damage and decreased antioxidant capacity, photochemical efficiency, leaf level photosynthesis, seed set, grain number and grain yield per spike. Impact of HN and HD was similar on all traits. Greater impact on seed set, grain number and grain yield per spike was observed at HDN compared with HN and HD. These results suggest that HN and HD during anthesis cause damage of a similar magnitude to winter wheat.     

Metabolic adaptations of mullet Rhinomugil corsula (Hamilton) with special reference to energy utilization

While the respiratory quotient (R.Q.) of Rhinomugil corsula in air-saturated water remains near unity at all levels of random activity, the ammonia quotient (A.Q. = volume or mole: mole relation of ammonia excreted to oxygen consumed) is higher at lower levels of activity, indicating relatively higher protein utilization in less active fish. The mean routine R.Q. values of R. corsula in air-saturated water at temperatures of 30 and 35°C are 0.91 and 0.95 respectively. Assuming that the major sources of ammonia excreted are certain predominant free amino acids, an estimate of caloric break-up of routine meta-bolism of R. corsula suggests that the fish is completely aerobic in air-saturated water and that it derives 14, 44 and 42% of energy from proteins, carbohydrates and fats respectively from a total of 567 cal/kg fish/h at 30°C (15, 55 and 30% at 35°C). At oxygen concentrations below air saturation, R.Q. and A.Q. values of R. corsula increase with decrease in ambient oxygen indicating an increase in anaerobic metabolism and protein utilization. The correlation between the trends of R.Q. and A.Q. levels are similar to that observed earlier in Tilapia mossambica. During hypoxia (1.6 mg O₂/l at 30°C) R. corsula derives about half its energy for sustenance and activity anaerobically. The mullet does not appear to accumulate an oxygen debt during hypoxia.     

Production of polyclonal antiserum against recombinant VP28 protein and its application for the detection of white spot syndrome virus in crustaceans

The VP28 gene of white spot syndrome virus (WSSV) was cloned into pRSET B expression vector. The VP28 protein was expressed as a protein with a 6-histidine taq in Escherichia coli GJ1158 with NaCl induction. Antiserum was raised against this recombinant-VP28 protein in rabbits and it recognized VP28 protein in naturally and experimentally WSSV-infected shrimp, marine crabs, freshwater prawns and freshwater crabs. The antiserum did not recognize any of the other known WSSV structural proteins. Various organs such as eyestalks, head muscle, gill tissue, heart tissue, haemolymph, tail tissue and appendages were found to be good materials for detection of WSSV using the antiserum and detection of WSSV was successful in experimentally infected Penaeus monodon and P. indicus at 12 and 24 h post-infection (p.i.), respectively. The antiserum was capable of detecting WSSV in 5 ng of total haemolymph protein from WSSV-infected shrimp.     

Mortality of the tobacco caterpillar,Spodoptera litura (F.), when treated withBacillus Thuringiensis combinations with boric acid and insecticides

Bacillus thuringiensis Berliner in combination with 0.1, 0.5, 1.0, 1.5 and 2% boric acid caused 100% mortality of the tobacco caterpillar,Spodoptera litura (F.), irrespective of instar, in a much shorter period (1.77 to 3.61 days) than with boric acid or the pathogen alone. The toxicity ofB. thuringiensis in combination with dicrotophos at 0.02 and 0.04%, with fenitrothion at 0.025 and 0.05%, or with dichlorvos at 0.01 and 0.05%, was enhanced.     

Influence of temperature and salinity on survival of the freshwater mullet, Rhinomugil corsula (Hamilton)

The upper incipient lethal temperatures of the freshwater mullet, Rhinomugil corsula, acclimated to 15, 20, 25, 30 and 35°C in fresh water, were 32.4, 34.1, 36.0, 36.2 and 36.5°C respectively, and the corresponding lower lethal temperatures were 10.5, 11.5, 13.2, 15.8 and 19.5°C. The mullet has a total tolerance (area of thermal polygon) of 569°C with an upper and lower thermal tolerance of 253 and 316°C². Likewise, the total resistance of the mullet was 391°C², with upper and lower resistance zones of 181 and 210°C respectively. The upper critical temperatures of swimming inhibition of R. corsula (17.2 cm; acclimation 30°C), determined in a swimming tunnel, were 35.2, 34.6 and 34.2 for water current velocities of 38, 62 and 77 cm s^?1 respectively. The corresponding lower critical temperatures were 26.2, 27.5 and 28.1°C. These results indicated the stenothermal nature of the mullet by comparison with other fishes, e.g. Tilapia mossambica.In tests on the influence of ambient salinity on thermal resistance, R. corsula survived longest at 7‰ (iso-osmotic salinity). At salinities above and below this point, survival times were shorter at any lethal temperature. In a tentative scheme for quantification of stress due to temperature and salinity at death (after acclimation to 30°C and tested at 37°C), the hypo-osmotic and hyper-osmotic stress were estimated to be 50 and 31% of the thermal stress (100%) respectively.     

Effect of in vitro propagation methods on field performance of two strawberry cultivars

Summary Strawberry cultivars, Redcoat and Veestar, propagated by meristem culture (MC), callus culture (CC) and direct shoot regeneration (DR) from leaf disks were compared for their vegetative and reproductive characters with standard runner (SR) propagated plants under field conditions. In the planting year, in vitro propagated plants of both cultivars had the same number of leaves as SR plants, but in vitro propagated Redcoat produced fewer stolons per plant than SR plants. However, in the following year, in vitro propagated mother plants of both cultivars had more leaves and higher runner production than SR mother plants. Flowering and fruiting behaviour of Veestar was not appreciably influenced by in vitro propagation methods. However, in vitro propagated plants of Redcoat flowered earlier and produced more flowers and fruits than SR plants, but still maintained normal berry weight. Among in vitro propagated plants, DR plants of Redcoat were the earliest to flower, whereas MC plants produced more flowers and fruits. The field performance of the first daughter plants derived from the in vitro propagated plants was consistent with their respective mother plants. Leaf shape of both cultivars was not altered by in vitro propagation. Phenotypic abnormalities were mainly confined to occurrence of yellow leaf variants in MC and CC plants and occasional appearance of plants with irregular flowering and growth habit among CC plants.NRCC No. 38004     

Estimation of Deposition Velocities for 85Sr, 131I, 137Cs on Spinach,Radish and Beans Leaves in a Tropical Region Under Simulated Fallout Conditions

Poly dispersive aerosols of SrCl₂, NaI, CsCl having a size distribution of 2.33 m (Activity Median Aerodynamic Diameter, [AMAD]) with a geometric standard deviation of 1.83 m are used for the determination of deposition velocity for ⁸⁵Sr, ¹³¹I and ¹³⁷Cs aerosols on tropical spinach (Spinicia olericia), radish (Raphanous sative) and beans (Phasolous valugeries) plant leaves. The experiments were carried out in a specially designed exposure chamber to simulate deposition under accidental releases of radioactivity in tropical environment. The rates of particles deposition are expressed as a function of plant surface area and of plant dry weight. The deposition velocities obtained are in the range of 10^–6 to 10^–7 m/s. These values differ significantly from those in temperate regions. The lower values for deposition velocities (v _g) for the tropical environment is attributed due to high humidity. Therefore, the deposition of suspended aerosols on leaf surfaces caused by impaction and Brownian diffusion becomes slower in tropical environment and resulted into lower value of deposition velocities.     

Specific mutations induced by triplex-forming oligonucleotides in mice

Triplex-forming oligonucleotides (TFOs) recognize and bind to specific duplex DNA sequences and have been used extensively to modify gene function in cells. Although germ line mutations can be incorporated by means of embryonic stem cell technology, little progress has been made toward introducing mutations in somatic cells of living organisms. Here we demonstrate that TFOs can induce mutations at specific genomic sites in somatic cells of adult mice. Mutation detection was facilitated by the use of transgenic mice bearing chromosomal copies of the supF and cII reporter genes. Mice treated with a supF-targeted TFO displayed about fivefold greater mutation frequencies in the supF gene compared with mice treated with a scrambled sequence control oligomer. No mutagenesis was detected in the control gene (cII) with either oligonucleotide. These results demonstrate that site-specific, TFO-directed genome modification can be accomplished in intact animals.     

Antibodies to the core protein of lymphadenopathy-associated virus (LAV) in patients with AIDS

Lymphadenopathy-associated virus ( LAV ), a human T- lymphotrophic retrovirus isolated from a homosexual man with lymphadenopathy, has been causally associated with acquired immunodeficiency syndrome (AIDS). A sensitive and specific radioimmunoprecipitation test was developed for the detection of antibodies to the major core protein of LAV , p25 (molecular weight 25,000). Antibody to LAV p25 was found in the serum of 51 of 125 AIDS patients, 81 of 113 patients with lymphadenopathy syndrome, 0 of 70 workers at the Centers for Disease Control (some of whom had handled specimens from AIDS patients), and 0 of 189 random blood donors. Of a group of 100 homosexual men from San Francisco whose serum was obtained in 1978, only one had antibody to LAV p25; in contrast, of a group of 50 homosexual men in the same community whose serum was obtained in 1984, 12 had antibodies to LAV p25.     

Capillary wrinkling of floating thin polymer films

A freely floating polymer film, tens of nanometers in thickness, wrinkles under the capillary force exerted by a drop of water placed on its surface. The wrinkling pattern is characterized by the number and length of the wrinkles. The dependence of the number of wrinkles on the elastic properties of the film and on the capillary force exerted by the drop confirms recent theoretical predictions on the selection of a pattern with a well-defined length scale in the wrinkling instability. We combined scaling relations that were developed for the length of the wrinkles with those for the number of wrinkles to construct a metrology for measuring the elasticity and thickness of ultrathin films that relies on no more than a dish of fluid and a low-magnification microscope. We validated this method on polymer films modified by plasticizer. The relaxation of the wrinkles affords a simple method to study the viscoelastic response of ultrathin films.