Physiological Changes in Phaseolus vulgaris in Response to Long-term Ozone Exposure

The effects of ozone on Phaseolus vulgaris cv. Lit were investigatedusing open-top chambers (OTCs) ventilated with charcoal andPurafil filtered air (CF treatments), ambient air (NF treatments)and ambient air to which low, medium or high concentrationsof ozone were added (NFL, NFM and NFH). Ozone additions of 8,16 and 23 nl l^–1 were made during phase 1 of the experiment(0–44 d after emergence, DAE), and additions of 15, 30and 47 nl l^–1 were made during phase 2 (45–99 DAE).Ozone was added to the chambers between 1100 and 1800 h GMT,for 3 or 4 consecutive days each week. The seasonal 7-h meanozone concentrations were 8, 21, 27, 33 and 38 nl l^–1in the CF, NF, NFL, NFM and NFH treatments, respectively. No visible symptoms of ozone injury or significant physiologicalchanges were detected in P. vulgaris during phase I of the experiment.In phase 2, the photosynthesis (Pn) and stomatal conductance(gs) of NFH-plants were inhibited by 73% and 86%, respectively,during ozone exposure, and recovered to pre-exposure valueson the following day. These observations were made prior tothe appearance, 60 DAE, of bronze lesions on the leaves of NFH-plants.The photosynthetic capacity and gs of NFH-leaves decreased asthe severity of ozone injury increased. Rates of weight lossfrom excised leaves also increased with increasing ozone injury.Microscopic investigations of the bronzed regions revealed extensivecellular breakdown, including tonoplast and chloroplast enveloperupture, and the aggregation of the cytoplasmic contents towardsone end of the cell. Severely damaged leaves abscised from the plants, resultingin premature canopy senescence in the NFM and NFH treatments.This, coupled with the lower photosynthetic capacity of existingleaves led to 25 % lower yield in the NFH than the NF treatment(P < 0.05). Phaseolus vulgaris, green bean, ozone, symptom development, photosynthesis, cell ultrastructure     

The detection of apple chlorotic leafspot virus by a modified procedure of enzyme-linked immunosorbent assay (ELISA)

The technique of enzyme-linked immunosorbent assay (ELISA) was modified to enable detection of apple chlorotic leafspot virus (CLSV) both in herbaceous hosts and in several naturally infected fruiting and ornamental woody host species. Some of the characteristics of the modified method as used with different virus-host combinations are described.     

Seasonal Dynamics of Biomass and Mineral Nutrient Partitioning in Mature Kiwifruit Vines

The accumulation of dry matter plus macro- and micronutnentsby various components of 6-year-old, field-grown kiwifruit vines(Actinidia deliciosa var deliciosa cv Hayward) was recordedover one season Twenty vines were harvested periodically throughoutthe year and separated into perennial components (roots <20 mm diameter, structural roots, stump, stem, cordon, one-year-oldfruiting wood) and current season's growth (non-fruiting shoots,laterals on fruiting wood, leaves and fruit) There was minimalseasonal variation (CVs < 7%) in biomass change in perennialcomponents of the vine Concentrations in these components eitherfluctuated about a constant value, or indicated a strong seasonaldependence Changes in biomass and nutnent concentrations incurrent season's growth, however, were very regular Prior tobudbreak, below-ground components contained between 48 and 81% of the total content of each element Roots < 20 mm diametercontained more total nutrient than any other perennial componentof the vine during the season, with the exception of Zn andCu, which were concentrated in the cordon There was consistentaccumulation of each nutrient from budbreak until harvest Ratesof greatest uptake occurred in the month following budbreak,or in the 3 weeks after anthesis Between dormancy and harvest,whole-vine contents increased for all nutrients Increases inFe, Mg, P, S and Zn ranged from 21 % (Zn) to 88% (Mg), and inB, Ca, Cl, Cu, K, N and Mn from 109% (Cu) to 302% (Cl) Despitethe large requirements of the current season's growth, net changesin the seasonal content of perennial components were relativelysmall Copper, Mg, P, N and Cl were the elements in which perennialreserves were utilized to the greatest extent to meet transientdeficits between nutnent demand for the current season’sgrowth, and that recently taken up from soil Generally, reserves utilized during the period of vegetativegrowth were replaced by harvest-time These observations, basedon application of a single fertiliser dressing before budbreak,suggest the vine maintains satisfactory fertility without theneed for late-season or post-harvest applications of fertiliserto supplement nutrient reserves, as occurs with some other fruitingcrops Actinidia deliciosa, kiwifruit, mineral nutrition, seasonal accumulation, whole-plant harvesting     

Recognition of Bacterial Initiator tRNA by an Initiation Factor

Initiation factor F2a of E. coli seems to recognize only fMet-tRNA_f. This may be analogous to the recognition of other aminoacyl-tRNAs by elongation factor T.     

Development of Eimeria auburnensis in Cell Cultures

SYNOPSIS. Monolayer established cell line cultures of bovine kidney (Madin-Darby) and human intestine (Intestine 407), as well as embryonic bovine tracheal and embryonic spleen cell line cultures were inoculated with E. auburnensis sporozoites and observed for a maximum of 22 days. Mature 1st generation schizonts developed in the kidney, tracheal and spleen cells. In the intestine cells, trophozoites were seen in 3 of 4 experiments, but schizonts were not found. Sporozoites penetrated cells, beginning within a few minutes after inoculation. Penetration was usually accomplished within 10 seconds, and the body of the sporozoite underwent a slight constriction as it passed thru the host cell membrane. Some sporozoites left cells. Numerous intracellular sporozoites were observed in kidney, tracheal and spleen cultures. Crescent bodies were seen in the parasitophorous vacuole as early as 1 day after inoculation. At this time, the nuclei of most intracellular sporozoites had changed from vesicular to compact. Beginning 4 days after inoculation, enlarged sporozoites and parasites having a sporozoite shape, but with 2-5 nuclei, were frequently seen. These enlarged sporozoites and sporozoite-shaped schizonts evidently transformed into trophozoites and spheroidal schizonts by means of lateral outpocketings. Few trophozoites were seen. More immature schizonts developed in kidney cells than in the other cell types. The numbers of mature schizonts observed in kidney and tracheal cells were similar, but development occurred less consistently in the latter. Few immature and mature schizonts developed in spleen cells. Mature schizonts, first seen 9 days after inoculation, were considerably smaller than those reported from calves. Some motile merozoites were seen; evidently no development beyond these occurred. The nucleus and nucleolus of host cells were enlarged; this enlargement was not as pronounced as in infections in calves. Multiple host cell nuclei were frequently observed. Degenerative changes in the cultured cells and in the parasites usually occurred, beginning 9-17 days after inoculation; these were more pronounced in the spleen cells than in the others.     

Carbohydrate Transport in Trypanosoma gambiense*

SYNOPSIS. The uptake of ¹⁴C-labeled carbohydrates by Trypanosoma gambiense was studied. Glucose, mannose, glycerol, 2-deoxyglucose and fructose were rapidly absorbed by the parasite, and all had saturation kinetics. The glucose analog 3-O-methylglucose was not taken up by T. gambiense. Competitive inhibition experiments indicate that there are 2 transport loci for the tested substrates. It is suggested that there is a “glucose site” thru which glucose, mannose and glycerol, but not fructose, are transported and a “fructose site” thru which only fructose is transported. The specificity of the glucose-transporting mechanism appears to differ from those of other animals.     

Eimeria ahtanumensis n. sp. from the Northwestern Fence Lizard Sceloporus occidentalis in Central Washington

SYNOPSIS Eimeria ahtanumensis n. sp. is described from the northwestern fence lizard Sceloporus occidentalis. The sporulated oocysts are generally cylindrical with rounded ends, averaging 34.2 by 19.7 μ. No oocyst residuum or micropyle is present. The ellipsoidal sporocysts average 10.5 by 8.8 μ; each has a distinct sporocyst residuum composed of spherical granules located against the sides of the sporocysts. The elongate sporozoites, lying head to tail in the sporocyst, average 16.5 by 2.5 μ when excysted. Endogenous development occurs in the epithelial lining of the gall bladder and bile duct. E. ahtanumensis is compared to other similar lizard coccidia.