Comparative transmission of, and varietal reaction to, three isolates of rice tungro virus disease

Comparative transmission by leafhoppers of three tungro isolates obtained from the Philippines, India and Malaysia, and of an infectious clone of the Philippine isolate of rice tungro bacilliform virus (RTBV) by agroinoculation, was conducted on 12 rice cultivars. The symptoms, including height of inoculated plants were recorded and the efficiency of RTBV and rice tungro spherical virus (RTSV) transmission was determined by enzyme-linked immunosorbent assay. In most cases, the reduction of height and leaf symptoms of plants infected with RTBV and/or RTSV by the three isolates were similar in any given cultivar. On cultivar ASD 7 , the Malaysian isolate showed more severe yellow orange leaf discolouration symptoms than the Indian isolate which in turn had more severe leaf discolouration than the Philippine isolate. On the other hand, cultivars ASD 7 and Ptb 18 produced the most severe yellow orange leaf discolouration when agroinoculated with an infectious RTBV clone of the Philippine isolate. There was some variation in the transmission profile of the two tungro viruses among the three isolates. However, there was no one clear set of characteristics by which one could use cultivars to distinguish isolates. The amount of viral DNA in agroinfected plants of cultivars Utri merah, Balimau putih, Utri Rajapan and ARC 11554 was low, while the amount was high in cultivars TN1, ASD7, Ptb 18 and TKM 6. There was high correlation between the amount of viral coat protein by ELISA and viral nucleic acid by DNA hybridisation on 10 agroinoculated rice cultivars; this might indicate that similar proportions of the total RTBV DNA are encapsidated in each cultivar.     

Influence of Summer and Autumn Nutrition on Body Condition and Reproduction in Lactating Mule Deer

ABSTRACT Recent work suggests that availability and quality of forage in late summer and early autumn, a time when female ungulates face multiple energetic demands, is critical to reproduction in wild ungulates. Therefore, we examined direct links between nutritional quality of diets, body condition, and reproduction of lactating mule deer. Using captive mule deer, we tested the hypothesis that females consuming diets with lower digestible energy (DE; kJ/g) would have lower DE intake rates (DEI; MJ/day), have less body fat and muscle, have later estrus cycles, and have lower pregnancy and twinning rates. Deer fed lower DE diets had lower DEI during summer and autumn. In turn, deer with lower DEI, regardless of diet DE, had lower body mass, body fat, and muscle thickness. When nutritional quality of diets began to decline earlier in the summer, relationships between food quality, DEI, and body condition were stronger. Although DEI did not influence estrus date for deer that became pregnant before 21 December, deer with lower DEI had a lower probability of becoming pregnant and had a lower probability of producing twins. Measures of body condition in October (i.e., body mass, body fat, and muscle depth) predicted pregnancy and twinning rates in mule deer. Serum concentration of hormones leptin and Insulin Growth Factor 1 were not good predictors of body condition or reproduction. These findings suggest that managers concerned with productivity of mule deer populations should consider focusing on assessing and improving quality of forage available in summer and autumn.     

Variations in Protein Synthesis in Different Regions of Greening Leaves of Barley Seedlings and Effects of Imposed Water Stress

Water stress, applied to the roots of six-day-old barley seedlingsmarkedly reduced the capacity of their leaves to synthesizeproteins during greening, a process that normally involves intensesynthetic activity. Upon illumination of etiolated seedlingsprotein synthesis commenced most rapidly in the basal region,and then declined in activity. Thereafter, in turn, the middleand apical regions exhibited a similar pattern of syntheticactivity; this is indicative of a ‘wave’ of proteinsynthesis progressing from the base of the leaf to the apexas greening proceeded. The synthesis of proteins varied bothquantitatively and qualitatively in different regions of theleaf during greening. For example, there was a noticeable increasein ribulose-1, 5-bisphosphate carboxylase synthesis in the apicalregion of the leaf compared to the basal region. Water stressreduced protein synthesis in all regions of the leaf, althoughmost effectively in the oldest, apical regions. Upon returnto full water status, the basal regions recovered the most rapidlyand to the greatest extent. Similar results were obtained whenboth intact greening leaves, and isolated segments from differentregions of the leaf were used. The reduction in protein synthesiselicited by water stress was not due to a selective quantitativechange in any particular protein; one protein, of an approximatemolecular weight of 60 kD, appeared to be synthesized only understress conditions. Key words: Water stress, Protein synthesis, Barley seedlings     

Desiccation-Tolerant and Desiccation-Intolerant Stages during the Development and Germination of Phaseolus vulgaris Seeds

Embryonic axes of Phaseolus vulgaris undergo a transition fromdesiccation-intolerance to desiccation-tolerance in the courseof their development. Biochemical and ultrastructural observationsindicate that desiccation and rehydration during the early intolerantdevelopmental stages drastically reduces the metabolic and cellularintegrity of the axis. During the desiccation-tolerant stagesuch perturbations do not occur. Coincident with the acquisitionof desiccation-tolerance during development the seeds gain thecapacity to germinate upon subsequent rehydration. Drying presumablyacts to terminate developmental processes and to initiate themetabolic processes essential for the completion of germination.During germination of the mature axis, desiccation and rehydration,up to 12 h from the start of imbibition, does not affect subsequentseedling growth and development. But gradually desiccation-tolerancedecreases and metabolism is severely and irreversibly reducedby drying.