scholarly journals Plasmodium oocysts respond with dormancy to crowding and nutritional stress

2020 ◽  
Author(s):  
Tibebu Habtewold ◽  
Aayushi A. Sharma ◽  
Claudia A.S. Wyer ◽  
Ellen K.G. Masters ◽  
Nikolai Windbichler ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Rna Polymerase Iii ◽  
Nutritional Stress ◽  
Alternative Methods ◽  
Anopheles Coluzzii ◽  
Energy Reserves ◽  
Transmission Blocking ◽  
High Infection ◽  
Very High ◽  
Starvation Conditions

AbstractMalaria parasites develop and grow as oocysts in the mosquito for several days before being able to infect another human. During this time, mosquitoes take regular bloodmeals to replenish their nutrient and energy reserves needed for flight and reproduction. We hypothesized that supplemental bloodmeals are critical for oocyst growth and that experimental infection protocols, typically involving a single bloodmeal, cause nutritional stress to developing oocysts. Therefore, enumerating oocysts independently of their growth and differentiation state may lead to erroneous conclusions regarding the efficacy of malaria transmission blocking interventions. We tested this hypothesis in Anopheles coluzzii mosquitoes infected with human and rodent parasites Plasmodium falciparum and Plasmodium berghei, respectively. We find that oocyst growth rates decrease at late developmental stages as infection intensities increase; an effect exacerbated at very high infection intensities. Oocyst growth and differentiation can be restored by supplemental bloodmeals even at high infection intensities. We show that high infection intensities as well as starvation conditions reduce RNA Polymerase III activity in oocysts unless supplemental bloodmeals are provided. Our data suggest that oocysts respond to crowding and nutritional stress by employing a dormancy-like strategy and urge development of alternative methods to assess the efficacy of transmission blocking interventions.

scholarly journals Plasmodium Oocysts Respond With Dormancy to Crowding and Nutritional Stress

2020 ◽  
Author(s):  
Tibebu Habtewold ◽  
Aayushi Sharma ◽  
Claudia Wyer ◽  
Ellen Masters ◽  
Nikolai Windbichler ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Rna Polymerase Iii ◽  
Nutritional Stress ◽  
Alternative Methods ◽  
Anopheles Coluzzii ◽  
Energy Reserves ◽  
Transmission Blocking ◽  
High Infection ◽  
Time Of Infection ◽  
Very High

Abstract Malaria parasites develop as oocysts in the mosquito for several days before they are able to infect a human host. During this time, mosquitoes take regular bloodmeals to replenish their nutrient and energy reserves needed for flight and reproduction. We hypothesized that these bloodmeals are critical for oocyst growth and that experimental infection protocols, typically involving a single bloodmeal at the time of infection, cause nutritional stress to the developing oocysts. Therefore, enumerating oocysts disregarding their growth and differentiation state may lead to erroneous conclusions about the efficacy of transmission blocking interventions. Here, we examine this hypothesis in Anopheles coluzzii mosquitoes infected with the human and rodent parasites Plasmodium falciparum and Plasmodium berghei, respectively. We found that oocyst growth rates decrease at late developmental stages as infection intensities increase; an effect exacerbated at very high infection intensities. Oocyst growth and differentiation are restored with post infection bloodmeals even at high infection intensities. High infection intensities and starvation conditions reduce RNA Polymerase III activity in oocysts unless supplemental bloodmeals are provided. Our results suggest that oocysts respond to crowding and nutritional stress with a dormancy-like strategy, which urges the development of alternative methods to assess the efficacy of transmission blocking interventions.

scholarly journals Plasmodium oocysts respond with dormancy to crowding and nutritional stress

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tibebu Habtewold ◽  
Aayushi A. Sharma ◽  
Claudia A. S. Wyer ◽  
Ellen K. G. Masters ◽  
Nikolai Windbichler ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Rna Polymerase Iii ◽  
Nutritional Stress ◽  
Alternative Methods ◽  
Anopheles Coluzzii ◽  
Energy Reserves ◽  
Transmission Blocking ◽  
High Infection ◽  
Time Of Infection ◽  
Very High

AbstractMalaria parasites develop as oocysts in the mosquito for several days before they are able to infect a human host. During this time, mosquitoes take bloodmeals to replenish their nutrient and energy reserves needed for flight and reproduction. We hypothesized that these bloodmeals are critical for oocyst growth and that experimental infection protocols, typically involving a single bloodmeal at the time of infection, cause nutritional stress to the developing oocysts. Therefore, enumerating oocysts disregarding their growth and differentiation state may lead to erroneous conclusions about the efficacy of transmission blocking interventions. Here, we examine this hypothesis in Anopheles coluzzii mosquitoes infected with the human and rodent parasites Plasmodium falciparum and Plasmodium berghei, respectively. We show that oocyst growth and maturation rates decrease at late developmental stages as infection intensities increase; an effect exacerbated at very high infection intensities but fully restored with post infection bloodmeals. High infection intensities and starvation conditions reduce RNA Polymerase III activity in oocysts unless supplemental bloodmeals are provided. Our results suggest that oocysts respond to crowding and nutritional stress with a dormancy-like strategy, which urges the development of alternative methods to assess the efficacy of transmission blocking interventions.

scholarly journals High infection rates of the tick Hyalomma anatolicum anatolicum with Trypanosoma theileri

2004 ◽  
Vol 71 (4) ◽  
Author(s):  
A.A. Latif ◽  
M.A. Bakheit ◽  
Amna E. E. Mohamed ◽  
E. Zweygarth
Keyword(s):  
Developmental Stages ◽  
Blood Parasites ◽  
Hyalomma Anatolicum ◽  
Hyalomma Anatolicum Anatolicum ◽  
Regular Control ◽  
High Infection ◽  
Centrifugation Technique ◽  
Very High ◽  
Peak Parasitaemia ◽  
Trypanosoma Theileri

A crossbred calf (3 months old) obtained from a farm where regular control of ticks was practised and found to be free of blood parasites was inoculated with 20 ml pooled blood collected from four field cattle which had very low Trypanosoma theileri parasitaemias (one parasite per 70 µl blood as determined by the haematocrit centrifugation technique). Trypanosoma theileri was present in the blood 6 days after injection and a peak parasitaemia of 42 parasites per 70 µl blood was recorded by day 12. Hyalomma anatolicum anatolicum nymphs were applied on the ears of the calf on day 8 and they dropped engorged by days 13 and 14. The resulting adult ticks were examined for the presence of T. theileri by severing a leg and making a smear of the clear haemolymph which exuded from the wound. The smear was fixed in methanol and stained with Giemsa stain. The infection rate with T. theileri in the ticks was 43.3 % (26 out of 60). The intensity of infection was very high and various developmental stages of the flagellates were observed (epimastigotes, sphaeromastigotes, trypomastigotes and other intermediate stages). The haemolymph from 12 ticks was also collected in tissue culture medium and the trypanosomes survived for 25 weeks before eventually dying. The results demonstrated unequivocally the high vectorial capacity of the tick H. a. anatolicum for T. theileri.

scholarly journals Temporal Dynamics of ‘Ca. Phytoplasma mali’ Load in the Insect Vector Cacopsylla melanoneura

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 592
Author(s):  
Valentina Candian ◽  
Monia Monti ◽  
Rosemarie Tedeschi
Keyword(s):  
Host Plants ◽  
Developmental Stages ◽  
Temporal Dynamics ◽  
Control Strategies ◽  
Vector Competence ◽  
Insect Vector ◽  
Life Stages ◽  
Candidatus Phytoplasma Mali ◽  
High Infection ◽  
Cacopsylla Melanoneura

The transmission of phytoplasmas is the result of an intricate interplay involving pathogens, insect vectors and host plants. Knowledge of the vector’s competence during its lifespan allows us to define more sustainable well-timed control strategies targeted towards the most worrisome life stages. We investigated the temporal dynamics of ‘Candidatus Phytoplasma mali’ load in Cacopsylla melanoneura in the different developmental stages in Northwest Italy. The phytoplasma load in the vector was evaluated in overwintering adults, nymphs and newly emerged adults after different acquisition access periods. Moreover, we followed the multiplication of the phytoplasma during the aestivation and the overwintering period on conifers. Our results confirmed the ability of remigrants to retain the phytoplasma until the end of winter. We also highlighted the high acquisition efficiency and vector competence, based on phytoplasma load, of nymphs and newly emerged adults. Therefore, particular attention should be paid to the management of overwintered C. melanoneura as soon as they return to the orchards, but also to newly emerged adults, particularly in orchards with a high infection rate and when the migration to conifers is delayed.

Sulfate-Bearing Soils: Problems with Calcium-Based Stabilizers

1996 ◽  
Vol 1546 (1) ◽  
pp. 62-69 ◽  
Author(s):  
Prakash B. V. S. Kota ◽  
Darren Hazlett ◽  
Les Perrin
Keyword(s):  
United States ◽  
Western United States ◽  
Alternative Methods ◽  
Parking Lots ◽  
Soluble Sulfate ◽  
Materials Used ◽  
Pavement Damage ◽  
Sulfate Induced Heave ◽  
Very High

Several roads, airfield pavements, and parking lots in Texas and other states in the western United States have suffered severe pavement damage due to expansive minerals formed from the reactions of calcium-based materials used to stabilize sulfate-bearing soils. Remediation costs for projects that suffer sulfate-induced heave damage are very high, because often the entire pavement may have to be removed and reconstructed. Observations from several projects are described to illustrate the phenomenon of sulfate-induced heave and the current methods to predict the problem. Two recent projects described include one using cement as a replacement for lime and a second using a double application of lime. The discussion also includes limitations of the present methods for determining the so-called soluble sulfate levels in soils. The practice of a double application of lime and several other alternative methods and their limitations are discussed. Although research has clearly identified the expansive minerals as being calcium bearing, no published investigations of non-calcium-based stabilizers that could effectively stabilize sulfate-bearing soils were found.

scholarly journals Response of Lithuanian Winter Wheat Advanced Lines to Common Bunt (Tilletia tritici (BJERK.) WINT)

2009 ◽  
Vol 63 (1-2) ◽  
pp. 51-56
Author(s):  
Vytautas Ruzgas ◽  
Žilvinas Liatukas
Keyword(s):  
Winter Wheat ◽  
Disease Incidence ◽  
Common Bunt ◽  
Infection Level ◽  
Breeding Lines ◽  
Tilletia Tritici ◽  
Resistance Sources ◽  
Resistant Lines ◽  
High Infection ◽  
Very High

Response of Lithuanian Winter Wheat Advanced Lines to Common Bunt (Tilletia tritici (BJERK.) WINT) The study was carried out at the Lithuanian Institute of Agriculture in an artificially inoculated nursery during 2006-2007. Resistance to common bunt in 2006 was tested for 71, in 2007 for 118 breeding lines of Lithuanian winter wheat from the competitive trial nursery. Additionally, 148 promising lines were selected and tested from the check nursery, which possessed some resistance in their pedigree ancestors. The average disease incidence in 2006 and 2007 was 80.9 and 63.5%, respectively. The very high infection level highlighted the genotypes with the most effective resistance under conditions highly favourable for common bunt. There were no lines without infected ears. Among the 29 breeding lines tested in the two years, two lines Bill/Aspirant and Dream/Lut.9329 were infected the least, 17.2% and 1.9% in 2006 and 18.5% and 7.8% in 2007, respectively. Most of the breeding lines were highly susceptible. Lines with disease incidence over 50% accounted for over 90% in 2006 and 80% in 2007 of the total lines tested. The most resistant lines had in their pedigrees the following resistance sources: genotypes Bill, Lut.9329, Strumok, Lut.9313, Lut.9358, Tommi as well as Dream, Haldor, 91002G2.1, 96/101, Bezenchiukskaya380.

scholarly journals Developmental expression of the 412 retrotransposon in natural populations of D. melanogaster and D. simulans

2000 ◽  
Vol 76 (3) ◽  
pp. 217-226 ◽  
Author(s):  
N. BORIE ◽  
C. LOEVENBRUCK ◽  
C. BIEMONT
Keyword(s):  
Expression Pattern ◽  
Copy Number ◽  
Developmental Stages ◽  
Population Sample ◽  
Natural Populations ◽  
Developmental Expression ◽  
Regulatory Sequences ◽  
Copy Numbers ◽  
Species Specific ◽  
Very High

We analysed the pattern of expression of retrotransposon 412 through developmental stages in various populations of Drosophila simulans and D. melanogaster differing in 412 copy number. We found that the 412 expression pattern varied greatly between populations of both species, indicating that such patterns were not entirely species-specific. In D. simulans, total transcripts increased with number of 412 copies in the chromosomes when this number was low, and then decreased for high copy numbers. D. melanogaster, which has a higher 412 copy number than D. simulans, had overall a lower global 412 expression, but again showed variation in 412 expression pattern between populations. These results suggest that in populations of D. simulans with low 412 copy number, the expression pattern of this element depends not only on copy number but also on host cellular regulatory sequences near which the elements were inserted. In D. simulans populations with high copy number overall transcription was on the contrary globally repressed, as observed in D. melanogaster. A population from Canberra (Australia) which had a very high 412 copy number was found to be associated with very high expression of 412 over all developmental stages, suggesting that the above 412 expression regulation processes are overcome in this population sample. The analysis of hybrids between geographically distinct populations of D. simulans showed that 412 expression was trans-regulated differently according to developmental stages, implying complex interactions between the 412 element and stage-specific host genes.

scholarly journals Greenhouse Tests with Nematocides for Control of Nematodes Attacking Tomato (Lycopersicon esculentum var. Rutgers) in Puerto Rico

1969 ◽  
Vol 46 (4) ◽  
pp. 319-327
Author(s):  
Alejandro Ayala
Keyword(s):  
Puerto Rico ◽  
Field Experiments ◽  
Percent Level ◽  
Parasitic Nematodes ◽  
Root Knot Nematode ◽  
High Infection ◽  
The Difference ◽  
Reniform Nematodes ◽  
Susceptible Tomato ◽  
Very High

It has been found that, in Puerto Rico, tomatoes are severely attacked by several species of plant parasitic nematodes and particularly by Meloidogyne incognita (the root-knot nematode) and Rotylenchulus reniformis, the reniform or kidney-shaped nematode. Several experiments were conducted to determine the efficacy of different nematocides against these pests. The last experiment conducted in the greenhouse using eight different nematocides and one of the most susceptible tomato varieties, Rutgers, is discussed. Evidence presented in the form of graphs and tables demonstrates that at least the four fumigants D-D, Dorlone, EDB, and Nemagon are effective in the control of both species of nematodes mentioned. Two compounds, Telone and Fumazone, although not completely effective against root knot, gave a perfect control of the reniform nematodes. Dorlone was superior to all other nematocides, giving the best results in relation to growth, weight of stem, yield, and general appearance of the plants. It also gave perfect control of the reniform and root-knot nematodes. The difference in height of plants over the control was statistically significant at the 5-percent level with EDB and at the 1-percent level with Dorlone and Nemagon. There was no significant statistical difference among the chemicals tested nor between the rest of the chemicals and the control. The severity of root-knot infection varied from degree 0, no infection, to degree 5, very high infection. Root knot was outstanding in the control plants, which showed a very high infection average of degree 5 for galling. At time of harvesting the plants were smaller than those under all the other treatments, but exhibited very little chlorosis and yellowing. In previous trials symptoms developed to a maximum only after blooming or the first picking of fruits. Blooming was retarded, which was shown by the small amount and weight of fruits. A very heavy gall and secondary root-formation was observed. Dorlone gave the best results and showed no phytotoxic effects. Similar observations have been made in field experiments. Phytotoxicity was shown by treatments with Nemagon, EDB, and DCB-60. This condition can be avoided using a lower dosage of the first two nematocides. DCB-60 proved to be ineffective.

Performance of Commercial Insecticide Formulations Against Different Developmental Stages of Insecticide-Resistant Tropical Bed Bugs (Hemiptera: Cimicidae)

2019 ◽  
Author(s):  
Xin-Yeng Leong ◽  
Dae-Yun Kim ◽  
Kai Dang ◽  
G Veera Singham ◽  
Stephen L Doggett ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Contact Method ◽  
Bed Bugs ◽  
Immersion Method ◽  
Resistance Level ◽  
Bed Bug ◽  
Lambda Cyhalothrin ◽  
Cimex Hemipterus ◽  
High Level ◽  
Very High

Abstract This study examined the presence of insecticide resistance in different developmental stages (adults, first instars, and eggs) of the tropical bed bug, Cimex hemipterus (F.) using several insecticide formulations. Adults and first instars of five strains (Queensland, Kuala Lumpur, Bukit Mertajam, Saujana, and Krystal Point) were evaluated using the surface contact method and compared with a susceptible strain (Monheim) of the common bed bug Cimex lectularius L. The insecticide formulations were used at their label rates in this study: Tandem (thiamethoxam [11.6%], lambda-cyhalothrin [3.5%]) at 183.96 mg/m2; Temprid SC (imidacloprid [21%], beta-cyfluthrin [10.5%]) at 106.13 mg/m2; Sumithion 20CS (fenitrothion [20%]) at 250 mg/m2; Pesguard FG161 (d-tetramethrin [4.4%], cyphenothrin [13.2%]) at 110 mg/m2; and Sumithrin 10SEC (d-phenothrin [10%]) at 100 mg/m2. Results showed a very high level of resistance to Pesguard FG161 (388.3 to >605.0 times) and Sumithrin (302.9 to >365.5 times) in all adults of the strains tested, whereas low to high levels of resistance were registered for Tandem (1.4–4.7 times), Temprid (7.3–16.7 times), and Sumithion (1.2–14.6 times) for adults of all bed bug strains. For first instars, resistance to the former two formulations were high to very high (31.4–118.1 times). In contrast, they showed lower resistance to Tandem, Temprid, and Sumithion (1.0–10.2 times). An immersion method used to test on bed bug eggs found high to very high resistance toward all tested formulations. Results demonstrate that the resistance level varies between bed bug developmental stages.

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