Effect of inoculum spore load, length of infection period, and leaf washing on occurrence of Peronospora tabacina Adam, (blue mould) of tobacco

1966 ◽  
Vol 17 (2) ◽  
pp. 133 ◽  
Author(s):  
AV Hill
Keyword(s):  
Incubation Period ◽  
Similar Increase ◽  
Spore Concentration ◽  
Peronospora Tabacina ◽  
Infection Period ◽  
Spore Number ◽  
Limited Series ◽  
Series Of Experiments ◽  
Different Strains ◽  
Spore Load

Leaves of tobacco plants cv. Virginia Gold were spray-inoculated with different concentrations of spores of Peronospora tabacina strain APT1 and kept wet for 2 to 16 hr. Incubation period and occurrence of the disease on leaves were related to spore concentration, length of the infection period, temperature, and leaf position. The length of the incubation period increased from approximately 3 to 8 days with decrease in spore number. There was a similar increase with decrease in the length of the infection period and with low temperatures. The number of disease lesions increased with spore number in the inoculum and with increase in the length of the infection period up to 8 hr; it was about 100% higher on washed than on unwashed leaves. All leaves of washed plants had the same number of lesions but with unwashed plants, the lowest leaf had the most lesions and the uppermost the least. In a limited series of experiments with APT2 on cv. Virginia Gold and cv. Sol, the results were similar to those reported for APT1. The host–pathogen reaction was modified by spore load and temperature, the result being a range of symptoms; this indicates the need for caution in the use of symptoms as a means for distinguishing between different strains of the pathogen and between levels of resistance. High spore concentrations and infection periods of 4 hr or longer were necessary for extensive occurrence of the pathogen in leaves.

Influence of taurocholate, taurochenodeoxycholate, and taurodehydrocholate on sulfobromophthalein transport into bile.

1979 ◽  
Vol 236 (1) ◽  
pp. E10
Author(s):  
S Binet ◽  
Y Delage ◽  
S Erlinger
Keyword(s):  
Bile Salts ◽  
Mixed Micelle ◽  
Mixed Micelles ◽  
Important Determinant ◽  
Micelle Formation ◽  
Similar Increase ◽  
Mixed Micelle Formation ◽  
Series Of Experiments

To test the hypothesis that incorporation of sulfobromophthalein (BSP) into mixed micelles could account for the increase in its biliary transport maximum (Tmax) by bile salts, we have compared in hamsters the influence on BSP Tmax of taurocholate and taurochenodeoxycholate (two micelle-forming physiological bile salts) to that of taurodehydrocholate, a bile salt which, in vitro, does not form micelles. In a first series of experiments, it was observed that taurocholate and taurochenodeoxycholate increased the secretion of phospholipid (40 and 53%, respectively), and cholesterol (50 and 110%, respectively), whereas taurodehydrocholate decreased the secretion of phospholipid (-31%) and cholesterol (-43%). This result suggests that, in vivo, taurodehydrocholate or its metabolites do not form mixed micelles. In a second series of experiments, it was seen that the three bile salts induced a similar increase in BSP Tmax (63% with taurocholate, 52% with taurochenodeoxycholate, and 51% with taurodehydrocholate). These results provide circumstantial evidence for the hypothesis that mixed micelle formation is not an important determinant of maximal BSP secretion into bile.

Simultaneous DO Control and Respiration Estimation

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1185-1195 ◽  
Author(s):  
Ulf Holmberg ◽  
Gustaf Olsson ◽  
Bengt Andersson
Keyword(s):  
Transfer Rate ◽  
Oxygen Uptake Rate ◽  
Oxygen Transfer Rate ◽  
Full Scale ◽  
Air Flow Rate ◽  
Relay Feedback ◽  
Fast Tracking ◽  
Limited Series ◽  
Series Of Experiments ◽  
Do Concentration

The oxygen uptake rate (or respiration) is a crucial variable in the operation of an activated sludge plant. A method has been developed and tried in full scale to estimate the respirat ion while controlling the dissolved oxygen. The strategy allows a simultaneous tracking of the respiration rate and the oxygen transfer rate. This has not been possible to do in earlier methods. The control strategy is dual in the sense that the control signal, the air flow rate, is used both to control the DO concentration and to excite the DO dynamics sufficiently to allow the parameters to be estimated. The excitation is introduced automatically by a relay feedback resulting in an oscillation of the DO around its set point. Tuning of the relay gain makes then a nice compromise between fast tracking and accurate control. The dual controller and estimator has been tested during a limited series of experiments in full scale at the Malmö Sewage works in Sweden.

scholarly journals The reproductive index from SEIR model of Covid-19 epidemic in Asean

2020 ◽  
Author(s):  
Pongkeaw Udomsamuthirun ◽  
Grittichon Chanilkul ◽  
Pongkarn Tongkhonburi ◽  
Chatcharawan Meesubthong
Keyword(s):  
Incubation Period ◽  
Maximum Rate ◽  
External Stimulus ◽  
Polynomial Equations ◽  
Third Order ◽  
Raw Data ◽  
Seir Model ◽  
Infection Period ◽  
Order Polynomial ◽  
The Difference

AbstractAs we calculate analytic to link the coefficient of third-order polynomial equations from raw data of an Asean to the SEIR model. The Reproductive index depending on the average incubation period and the average infection period and the coefficient polynomial equations fitted from raw are derived. We also consider the difference of the average incubation period as 5 days and 3 days with the average infection period as 10 day of an Asean. We find that the value of R0 are Indonesia (7.97), Singapore (6.22), Malaysia (3.86), Thailand (2.48), respectively. And we also find that Singapore has 2 values of R0 as 1.54 (16 Feb to 37 March) and 6.22 (31 March-4 April).The peak of infection rate are not found for Singapore and Indonesia at the time of consideration. The model of external stimulus is added into raw data of Singapore and Indonesia to find the maximum rate of infection. We find that Singapore need more magnitude of external stimulus than Indonesia. And the external stimulus for 14 days can stimulate to occur the peak of infected daily case of both country.

The vertical distribution of flying mosquitoes (diptera, culicidae) in west african savanna

1975 ◽  
Vol 65 (2) ◽  
pp. 269-277 ◽  
Author(s):  
W. F. Snow
Keyword(s):  
Vertical Distribution ◽  
Lunar Phase ◽  
Visual Responses ◽  
Open Ground ◽  
Limited Series ◽  
Suction Traps ◽  
Series Of Experiments ◽  
Four Levels ◽  
Set Up ◽  
The Vertical Distribution

AbstractThe vertical distribution of mosquitoes was investigated at Keneba in The Gambia, using flight traps and suction traps set up over open ground. Flight traps were used to sample three levels, ground to 1·37 m, 1·45–2·82 m, and 2·90–4·27 m. Suction traps were mounted in two series of experiments at three levels, 0·68, 2·13 and 3·51 m, and in a third series at four levels, 0·91, 305, 6·10 and 9·15 m. Most species, including Anopheles melas Theo., A. squamosus Theo., Aedes punctothoracis (Theo.), the Culex decens group, C. tritaeniorhynchus Giles, Mansonia africana (Theo.) and M. uniformis (Theo.), were most common near the ground, with catches declining progressively with height. C. thalassius Theo. was frequent at all levels, although the largest catches were taken at 9·15 m. Only C. neavei Theo. and C. weschei Edw. were more common in the higher traps. Although larger catches of A. melas and C. tritaeniorhynchus were taken during moonless periods, the numbers of other species were unaffected by lunar phase. In general, the presence or absence of moonlight had little effect on vertical distribution. However, C. thalassius and the C. decens group were shown to be more attracted to flight traps in moonlight, and it is concluded that visual responses were involved. A limited series of four-level, human-bait catches, with the catchers stationed at the same heights as the suction traps of the third series, produced results similar to those of the suction trap collections.

scholarly journals Biochemical studies of toxic agents. The metabolic formation of 1- and 2-menaphthylmercapturic acid

1968 ◽  
Vol 107 (4) ◽  
pp. 519-522 ◽  
Author(s):  
C. W. Hyde ◽  
L. Young
Keyword(s):  
Mercapturic Acids ◽  
Acid Excretion ◽  
Rat Urine ◽  
Alcohol Acetate ◽  
Toxic Agents ◽  
Biochemical Studies ◽  
Limited Series ◽  
Series Of Experiments ◽  
Derivatives Of ◽  
Chromatographic Evidence

1. Various derivatives of 1- and 2-methylnaphthalene, of the type C10H7·CH2X, were administered to rats and the urines of the dosed animals were examined for the presence of 1- and 2-menaphthylmercapturic acid by chromatographic and isolation procedures. A similar, but more limited, series of experiments was carried out with rabbits. 2. All the compounds were administered by subcutaneous injection with the exception of S-(1- and 2-menaphthyl)-l-cysteine, which were added to the food. 3. 1-Menaphthylmercapturic acid was isolated from the urine of rats after the administration of 1-menaphthyl chloride, bromide, alcohol, acetate and benzoate, S-(1-menaphthyl)-l-cysteine and S-(1-menaphthyl)glutathione. 4. 2-Menaphthylmercapturic acid was isolated from rat urine after administration of 2-menaphthyl chloride, S-(2-menaphthyl)-l-cysteine and S-(2-menaphthyl)-glutathione, and was detected chromatographically after injecting 2-menaphthyl bromide. 5. The corresponding mercapturic acids were isolated after administering 1- and 2-menaphthyl chloride and 1-menaphthyl acetate to rabbits, but not after giving 1- and 2-menaphthyl bromide and 1-menaphthyl alcohol, although chromatographic evidence of mercapturic acid excretion was obtained after injecting these compounds.

BSE and scrapie in perspective

1991 ◽  
Vol 1991 ◽  
pp. 41-41
Author(s):  
Hugh Fraser
Keyword(s):  
Incubation Period ◽  
Dose Response ◽  
Laboratory Tests ◽  
Host Protein ◽  
Response Curves ◽  
Specific Antigens ◽  
Dose Response Curves ◽  
Different Strains ◽  
Serial Dilutions

Scrapie-like diseases occur in sheep, goats, cattle, and other ruminants, in mink, and in man. An identical disease has now been seen in cats. There are no in vitro laboratory tests of infection which thus can only me recognised clinically, neuropathologically, with tedious animal transmissions, and by finding an altered host protein, called PrP, electrophoretically or ultrastructurally. There is no immunity in these diseases, due to an absence of infection-specific antigens, Assays of infection depend on incubation period measurements in mice infected intracerebrally with serial dilutions of infective sources. Dilution of different strains or isolates, or of single strains in different host genotypes, or using different routes of infection, result in distinct dose-response curves (incubation period/infecting dose).

scholarly journals Environment and Sporulation in Phytopathogenic Fungi Li. Conidia Formation in Peronospora Tabacina Adam as a Function of Temperature

1961 ◽  
Vol 14 (2) ◽  
pp. 198 ◽  
Author(s):  
IAM Cruickshank
Keyword(s):  
Incubation Period ◽  
Environmental Temperature ◽  
Phytopathogenic Fungi ◽  
Leaf Disk ◽  
Peronospora Tabacina ◽  
Response To Temperature

Using a leaf-disk technique an analysis was carried out to study the effect of environmental temperature on the length of the incubation period and sporulation intensity of P. tabacina. An analysis was also made of the sporulation response to temperature treatments prior to and during sporulation. The following points were demonstrated:

scholarly journals How many conidia are required for wound infection of apple plants by Neonectria ditissima

2016 ◽  
Vol 69 ◽  
pp. 238-245 ◽  
Author(s):  
M. Walter ◽  
S. Roy ◽  
B.M. Fisher ◽  
L. Mackle ◽  
N.T. Amponsah ◽  
...  
Keyword(s):  
Wound Infection ◽  
Spore Concentration ◽  
Lesion Development ◽  
Injury Type ◽  
Inoculation Methods ◽  
Disease Expression ◽  
Potted Plants ◽  
Inoculation Method ◽  
Apple Cultivars ◽  
Series Of Experiments

A series of experiments using potted plants in a glasshouse detached laterals in the laboratory and trees in the fi eld were undertaken to study wound size and number of Neonectria ditissima conidia required to produce European canker infections on freshlymade branch wounds in the apple cultivars Royal Gala and Scilate Th e wound types were needle and pin injuries rasp wounds and pruning cuts Spore concentrations from 102 to 106 conidia/ml and two inoculation methods (droplet and mist) were used Disease expression varied for the different assay types probably due to the conduciveness for infection of the diff erent incubation conditions Overall there was little eff ect on pathogen colonisation and lesion development based on injury type inoculation method or spore concentration >103 conidia/ml For freshlymade wounds such as pruning cuts or rasp wounds only three conidia were required for infection initiation in the glasshouse under highly conducive conditions 12 conidia in the laboratory on detached shoots and 10 to 30 conidia in the fi eld

scholarly journals Factors influencing the growth of normal and malignant cells in fluid culture media

1934 ◽  
Vol 115 (793) ◽  
pp. 278-297 ◽  
Keyword(s):  
Culture Media ◽  
Mouse Serum ◽  
Rat Serum ◽  
Fluid Media ◽  
Different Types ◽  
Old Rats ◽  
Series Of Experiments ◽  
Different Strains ◽  
Sarcoma Cells ◽  
Fluid Culture

In a former communication (Ludford, 1933,) attention has been directed to differences in the growth of mouse tumours in plasma and serum. With the aim of elucidating tire significance of these differences, further series of experiments have been carried out, which have brought to light new facts necessitating the revision of in my former conclusions, as well as those of previous investigators who have worked with fluid media, At the same time further insight has been gained into the complexity of the factors which influence the growth of tumours in serum. It has been found that different strains of transplantable tumours exhibit individual differences when grown in serum, and even tumours of the same strain show marked differences from time to time. Also, both. the type of growth and its extent are influenced by the source from which the serum is derived, that is, whether it is homologous or heterologous. In describing these experiments it will be necessary therefore to deal with different strains of tumours separately. Concerning this strain of tumour I am unable to add anything to the account published in my former paper (Ludford, 1933). Neither in mouse serum, nor in rat serum has it been possible yet to obtain good outgrowths of the sarcoma cells. Pure serum and diluted serum; serum, with and without, embryo extract; serum from young and old rats, male and female, both pregnant and non-pregnant; also different types of cover slips have all been tried without influencing the type of growth.

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