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1.
Sci Rep ; 13(1): 16798, 2023 10 05.
Article in English | MEDLINE | ID: mdl-37798302

ABSTRACT

Deaths from malaria remain staggering despite global support that drives research into new territories. One major gap is our understanding of the sexual biological aspects of the male mosquito, which maintain the vector population solidity. Although Anopheles funestus s.s. is an extremely efficient African vector, little is known about the network between its sexual physiology and gene expression. The Culicidae male's sexual maturity involves a suite of physiological changes, such as genitalia rotation that is necessary for successful mating to occur. We show that mating success is guided by genes and physiological plasticity. Transcriptome analysis between newly emerged males (immature) versus males with rotating genitalia (maturing) provides insight into possible molecular mechanisms regulating male sexual behaviour. Putative transcripts that were associated with male sexual maturation were identified and validated. The discovery of the functions of these transcripts could lead to identifying potential targets for innovative vector control interventions, and mosquito population suppression.


Subject(s)
Anopheles , Malaria , Animals , Male , Anopheles/genetics , Transcriptome , Mosquito Vectors/genetics , Gene Expression Profiling
2.
Antioxidants (Basel) ; 12(7)2023 Jun 30.
Article in English | MEDLINE | ID: mdl-37507911

ABSTRACT

The coordinating role of nuclear factor erythroid-2-related factor 2 (Nrf2) in cellular function is undeniable. Evidence indicates that this transcription factor exerts massive regulatory functions in multiple signaling pathways concerning redox homeostasis and xenobiotics, macromolecules, and iron metabolism. Being the master regulator of antioxidant system, Nrf2 controls cellular fate, influencing cell proliferation, differentiation, apoptosis, resistance to therapy, and senescence processes, as well as infection disease success. Because Nrf2 is the key coordinator of cell defence mechanisms, dysregulation of its signaling has been associated with carcinogenic phenomena and infectious and age-related diseases. Deregulation of this cytoprotective system may also interfere with immune response. Oxidative burst, one of the main microbicidal mechanisms, could be impaired during the initial phagocytosis of pathogens, which could lead to the successful establishment of infection and promote susceptibility to infectious diseases. There is still a knowledge gap to fill regarding the molecular mechanisms by which Nrf2 orchestrates such complex networks involving multiple pathways. This review describes the role of Nrf2 in non-pathogenic and pathogenic cells.

3.
Optim Lett ; : 1-42, 2023 Mar 17.
Article in English | MEDLINE | ID: mdl-37361017

ABSTRACT

Health and convenience are two indispensable indicators of the society promotion. Nowadays, to improve community health levels, the comfort of patients and those in need of health services has received much attention. Providing Home Health Care (HHC) services is one of the critical issues of health care to improve the patient convenience. However, manual nurse planning which is still performed in many HHC institutes results in a waste of time, cost, and ultimately lower efficiency. In this research, a multi-objective mixed-integer model is presented for home health care planning so that in addition to focusing on the financial goals of the institution, other objectives that can help increase productivity and quality of services are highlighted. Therefore, four different objectives of the total cost, environmental emission, workload balance, and service quality are addressed. Taking into account medical staff with different service levels, and the preferences of patients in selecting a service level, as well as different vehicle types, are other aspects discussed in this model. The epsilon-constraint method is implemented in CPLEX to solve small-size instances. Moreover, a Multi-Objective Variable Neighborhood Search (MOVNS) composed of nine local neighborhood moves is developed to solve the practical-size instances. The results of the MOVNS are compared with the epsilon-constraint method, and the strengths and weaknesses of the proposed algorithm are demonstrated by a comprehensive sensitivity analysis. To show the applicability of the algorithm, a real example is designed based on a case study, and the results of the algorithm over real data are evaluated.

4.
Microbiol Spectr ; : e0367122, 2023 Feb 27.
Article in English | MEDLINE | ID: mdl-36847501

ABSTRACT

Malaria inflicts the highest rate of morbidity and mortality among the vector-borne diseases. The dramatic bottleneck of parasite numbers that occurs in the gut of the obligatory mosquito vector provides a promising target for novel control strategies. Using single-cell transcriptomics, we analyzed Plasmodium falciparum development in the mosquito gut, from unfertilized female gametes through the first 20 h after blood feeding, including the zygote and ookinete stages. This study revealed the temporal gene expression of the ApiAP2 family of transcription factors and of parasite stress genes in response to the harsh environment of the mosquito midgut. Further, employing structural protein prediction analyses, we found several upregulated genes predicted to encode intrinsically disordered proteins (IDPs), a category of proteins known for their importance in regulation of transcription, translation, and protein-protein interactions. IDPs are known for their antigenic properties and may serve as suitable targets for antibody- or peptide-based transmission suppression strategies. In total, this study uncovers the P. falciparum transcriptome from early to late parasite development in the mosquito midgut, inside its natural vector, which provides an important resource for future malaria transmission-blocking initiatives. IMPORTANCE The malaria parasite Plasmodium falciparum causes more than half a million deaths per year. The current treatment regimen targets the symptom-causing blood stage inside the human host. However, recent incentives in the field call for novel interventions to block parasite transmission from humans to the mosquito vector. Therefore, we need to better understand the parasite biology during its development inside the mosquito, including a deeper understanding of the expression of genes controlling parasite progression during these stages. Here, we have generated single-cell transcriptome data, covering P. falciparum's development, from gamete to ookinete inside the mosquito midgut, uncovering previously untapped parasite biology, including a repertoire of novel biomarkers to be explored in future transmission-blocking efforts. We anticipate that our study provides an important resource, which can be further explored to improve our understanding of the parasite biology as well as aid in guiding future malaria intervention strategies.

5.
Sci Rep ; 12(1): 18814, 2022 11 05.
Article in English | MEDLINE | ID: mdl-36335172

ABSTRACT

Malaria parasites can affect vector-related behaviours, increasing transmission success. Using Anopheles gambiae and Plasmodium falciparum, we consider the effect of interaction between infection stage and vector age on diel locomotion in response to human odour and the expression of antennal chemosensory genes. We identified age-dependent behavioural diel compartmentalisation by uninfected females post-blood meal. Infection disrupts overall and diel activity patterns compared with age-matched controls. In this study, mosquitoes carrying transmissible sporozoites were more active, shifting activity periods which corresponded with human host availability, in response to human odour. Older, uninfected, blood-fed females displayed reduced activity during their peak host-seeking period in response to human odour. Age- and infection stage-specific changes in odour-mediated locomotion coincide with altered transcript abundance of select chemosensory genes suggesting a possible molecular mechanism regulating the behaviour. We hypothesize that vector-related behaviours of female mosquitoes are altered by infection stage and further modulated by the age post-blood meal of the vector. Findings may have important implications for malaria transmission and disease dynamics.


Subject(s)
Anopheles , Malaria , Animals , Female , Humans , Mosquito Vectors/parasitology , Anopheles/parasitology , Plasmodium falciparum/genetics , Gene Expression
6.
Commun Biol ; 4(1): 1161, 2021 10 07.
Article in English | MEDLINE | ID: mdl-34620990

ABSTRACT

Recent data show that parasites manipulate the physiology of mosquitoes and human hosts to increase the probability of transmission. Here, we investigate phagostimulant activity of Plasmodium-metabolite, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), in the primary vectors of multiple human diseases, Anopheles coluzzii, An. arabiensis, An. gambiae s.s., Aedes aegypti, and Culex pipiens/Culex torrentium complex species. The addition of 10 µM HMBPP to blood meals significantly increased feeding in all the species investigated. Moreover, HMBPP also exhibited a phagostimulant property in plant-based-artificial-feeding-solution made of beetroot juice adjusted to neutral pH similar to that of blood. The addition of AlbuMAXTM as a lipid/protein source significantly improved the feeding rate of An. gambiae s.l. females providing optimised plant-based-artificial-feeding-solution for delivery toxins to control vector populations. Among natural and synthetic toxins tested, only fipronil sulfone did not reduce feeding. Overall, the toxic-plant-based-artificial-feeding-solution showed potential as an effector in environmentally friendly vector-control strategies.


Subject(s)
Aedes/physiology , Anopheles/physiology , Culex/physiology , Mosquito Vectors/physiology , Organophosphates/administration & dosage , Plasmodium falciparum/chemistry , Aedes/drug effects , Animals , Anopheles/drug effects , Blood , Culex/drug effects , Feeding Behavior/drug effects , Host Microbial Interactions , Mosquito Vectors/drug effects , Organophosphates/metabolism
7.
J Ethnopharmacol ; 280: 114080, 2021 Nov 15.
Article in English | MEDLINE | ID: mdl-33798662

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Lorestan Province (Iran) has a great diversity of habitats and plant diversity and the people living in this province have a good knowledge of herbal therapies. AIM OF THE STUDY: In this study, the authors aimed to identify and report the medicinal plants used in the folk medicine of Lorestan. MATERIAL AND METHODS: The indigenous medicinal information was collected with a semi-structured open-ended questionnaire, interviews, and personal observations. The relative importance of the species were estimated through frequency of citations (FC). RESULTS: and discussion: A total of 555 plants belonging to 91 families were identified. The plants belong to Asteraceae with 62 species followed by Lamiaceae (56), Apiaceae (44), Fabaceae (41), and Brassicaceae (31). The plants were mostly used as a decoction or eaten raw (32%). Leaves (22%) were the most utilized plant parts followed by shoots (16%), and seeds (13%). Thymus daenensis, Thymus eriocalyx, Mentha longifolia, Mentha spicata, Mentha piperitha, Alium sativum, Quercus infectoria, Quercus persica, Ziziphora clinopodioides, and Malus domestica had the highest FC values. Most of the plants were used for gastrointestinal, respiratory, and skin problems. CONCLUSION: Lorestan is a region rich in medicinal plants. The local knowledge of herbal therapies can be used as complementary medicine, particularly by people in remote areas and as a guide for the future pharmacological and phytochemical studies. While the known medicinal plants can be harvested or cultivated for medical and pharmaceutical purposes, the less known plants with high FC scores can be investigated phytochemically and pharmacologically in the future studies.


Subject(s)
Health Knowledge, Attitudes, Practice , Medicine, Traditional/methods , Plant Preparations/pharmacology , Plants, Medicinal/chemistry , Adult , Aged , Ethnopharmacology , Female , Humans , Iran , Male , Middle Aged , Phytotherapy/methods , Plant Preparations/chemistry , Surveys and Questionnaires , Young Adult
8.
Biol Cell ; 113(2): 79-94, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33125724

ABSTRACT

In eco-evolutionary studies of parasite-host interactions, virulence is defined as a reduction in host fitness as a result of infection relative to an uninfected host. Pathogen virulence may either promote parasite transmission, when correlated with higher parasite replication rate, or decrease the transmission rate if the pathogen quickly kills the host. This evolutionary mechanism, referred to as 'trade-off' theory, proposes that pathogen virulence evolves towards a level that most benefits the transmission. It has been generally predicted that pathogens evolve towards low virulence in their insect vectors, mainly due to the high dependence of parasite transmission on their vector survival. Therefore, the degree of virulence which malaria parasites impose on mosquito vectors may depend on several external and internal factors. Here, we review briefly (i) the role of mosquito in parasite development, with a particular focus on mosquito midgut as the battleground between Plasmodium and the mosquito host. We aim to point out (ii) the histology of the mosquito midgut epithelium and its role in host defence against parasite's countermeasures in the three main battle sites, namely (a) the lumen (microbiota and biochemical environment), (b) the peritrophic membrane (physical barrier) and (c) the tubular epithelium including the basal membrane (physical and biochemical barrier). Lastly, (iii) we describe the impact which malaria parasite and its virulence factors have on mosquito fitness.


Subject(s)
Mosquito Vectors/parasitology , Plasmodium/physiology , Animals , Digestive System/parasitology , Genetic Fitness , Host-Parasite Interactions , Humans , Malaria/parasitology , Malaria/transmission , Plasmodium/growth & development , Plasmodium/pathogenicity
9.
Nat Ecol Evol ; 4(10): 1395-1401, 2020 10.
Article in English | MEDLINE | ID: mdl-32747772

ABSTRACT

Accumulating behavioural data indicate that aggregation pheromones may mediate the formation and maintenance of mosquito swarms. However, chemical cues possibly luring mosquitoes to swarms have not been adequately investigated, and the likely molecular incitants of these complex reproductive behaviours remain unknown. Here we show that males of the important malaria vector species Anopheles arabiensis and An. gambiae produce and release aggregation pheromones that attract individuals to the swarm and enhance mating success. We found that males of both species released significantly higher amounts of 3-hydroxy-2-butanone (acetoin), 6-methyl-5-hepten-2-one (sulcatone), octanal, nonanal and decanal during swarming in the laboratory. Feeding males with stable-isotope-labelled glucose revealed that the males produced these five compounds. A blend composed of synthetic analogues to these swarming odours proved highly attractive to virgin males and females of both species under laboratory conditions and substantially increased mating in five African malaria vectors (An. gambiae, An. coluzzii, An. arabiensis, An. merus and An. funestus) in semi-field experiments. Our results not only narrow a conspicuous gap in understanding a vital aspect of the chemical ecology of male mosquitoes but also demonstrate fundamental roles of rhythmic and metabolic genes in the physiology and behavioural regulation of these vectors. These identified aggregation pheromones have great potential for exploitation against these highly dangerous insects. Manipulating such pheromones could increase the efficacy of malaria-vector control programmes.


Subject(s)
Anopheles , Malaria , Animals , Female , Humans , Male , Mosquito Vectors , Pheromones , Reproduction
10.
J Nat Prod ; 82(4): 958-969, 2019 04 26.
Article in English | MEDLINE | ID: mdl-30916554

ABSTRACT

In a screening of Iranian plants for antiprotozoal activity a dichlomethane extract from the aerial parts of Helichrysum oocephalum showed in vitro antiprotozoal activity against Plasmodium falciparum and Leishmania donovani, with IC50 values of 4.01 ± 0.50 and 5.08 ± 0.07 µg/mL, respectively. The activity in the extract was tracked by HPLC-based activity profiling, and subsequent targeted preparative isolation afforded 24 compounds, including pyrones 22-24, phloroglucinol derivatives 12-19, and compounds containing both structural motifs (1-11, 20, and 21). Of these, 15 compounds were new natural products. The in vitro antiprotozoal activity of isolates was determined. Compound 3 showed good potency and selectivity in vitro against L. donovani (IC50 1.79 ± 0.17 µM; SI 53).


Subject(s)
Antiprotozoal Agents/pharmacology , Chromatography, High Pressure Liquid/methods , Helichrysum/chemistry , Inhibitory Concentration 50 , Iran , Leishmania donovani/drug effects , Plasmodium falciparum/drug effects
11.
Pathog Glob Health ; 113(8): 325-335, 2019 12.
Article in English | MEDLINE | ID: mdl-31910740

ABSTRACT

Approximately 120 years ago the link between mosquito and the malaria transmission was discovered. However, even today it remains an open question whether the parasite is able to direct the blood-seeking and feeding behavior of its mosquito vector to maximize the probability of transmission. If the parasite has this ability, could it occur only through the alteration of the vertebrate host's volatile organic compounds (VOCs) and/or the parasite alteration of the behavior of the infected vector in a manner that favors its transmission? Although some recent empirical evidence supports the hypothesis regarding the parasite ability in alteration of the vertebrate host's VOCs, the role of parasite alteration and behavioral differences between infected and uninfected female mosquitoes toward infected and uninfected hosts has not yet been considered in the implementation of control measures. This review will discuss the current evidence, which shows 1. Plasmodium can direct uninfected mosquito blood-seeking and feeding behavior via alteration of vertebrate-host odor profiles and production of phagostimulants and 2. Plasmodium also manipulates its vector during the sporogony cycle to increase transmission. Briefly, we also consider the next generation of methods for moving the empirical laboratory evidence to potential application in future integrated malaria control programs.


Subject(s)
Culicidae/parasitology , Plasmodium/physiology , Vertebrates/physiology , Animals , Feeding Behavior , Host-Parasite Interactions , Humans , Mosquito Vectors/parasitology , Mosquito Vectors/physiology
12.
Anesth Pain Med ; 9(6): e97229, 2019 Dec.
Article in English | MEDLINE | ID: mdl-32280619

ABSTRACT

BACKGROUND: Inadequate pain management is highly prevalent and is associated with significant costs and socioeconomic problems, which can lead to disparities in patient care. Specific groups are at higher risk of this problem. A few studies have evaluated the predictive risk factors of inadequate pain management. OBJECTIVES: This study evaluated the prevalence and predictive risk factors of inadequate pain management at the primary and secondary care centers with large sample size. METHODS: Patients who had been managed in primary and secondary care clinics were asked to report their personal characteristics, pain intensity, pain duration, and analgesics they were receiving in their first visit at our pain clinic. Zelman pain management index was calculated for each patient by analgesic potency minus mean pain intensity. The negative index showed incongruence between pain intensity and analgesic potency score (pain stronger than medication), indicating inadequate pain management. RESULTS: A negative pain management index was reported in 77% of the 511 recruited patients. Patients with more severe pain were more likely to experience inadequate pain management. A logistic model demonstrated women, people aged 45 - 65 years, illiterates, and obese patients were at higher risks of inadequate pain management. The pain management index was affected by sex and education (via higher pain intensities) and by age and BMI (via lower analgesic potency). CONCLUSIONS: Age, sex, education, and BMI are predictive risk factors of inadequate pain management as a prevalent problem in chronic pain patients.

13.
Cell Immunol ; 334: 11-19, 2018 12.
Article in English | MEDLINE | ID: mdl-30177348

ABSTRACT

Vγ9Vδ2 T cells, the dominant γδ T cell subset in human peripheral blood, are stimulated by phosphoantigens, of which (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate, is produced in the apicoplast of malaria parasites. Cell-free media from synchronised Plasmodium falciparum asexual ring, trophozoite, and schizont stage-cultures of high purity as well as media from ruptured schizont cultures, all stimulated Vγ9Vδ2 T cell proliferation, as did media from pure gametocyte cultures, whereas media from uninfected erythrocytes cultures did not. The media from ruptured schizont cultures and all the asexual and gametocyte stage cultures contained only background iron levels, suggesting that all erythrocyte haemoglobin is consumed as the parasites develop and supporting that the phosphoantigens were released from intact parasitized erythrocytes. The Vγ9Vδ2 T cell-stimulating agent was not affected by freezing, thawing or heating but was sensitive to phosphatase treatment, confirming its phosphoantigen identity. In summary, phosphoantigens are released from parasitised erythrocytes at all developmental blood stages.


Subject(s)
Antigens/immunology , Cell Proliferation/physiology , Erythrocytes/immunology , Malaria, Falciparum/immunology , Plasmodium falciparum/immunology , T-Lymphocytes/immunology , Hemoglobins/immunology , Humans
15.
PLoS Pathog ; 14(7): e1007076, 2018 07.
Article in English | MEDLINE | ID: mdl-30059535

ABSTRACT

Phosphate is an essential macronutrient required for cell growth and division. Pho84 is the major high-affinity cell-surface phosphate importer of Saccharomyces cerevisiae and a crucial element in the phosphate homeostatic system of this model yeast. We found that loss of Candida albicans Pho84 attenuated virulence in Drosophila and murine oropharyngeal and disseminated models of invasive infection, and conferred hypersensitivity to neutrophil killing. Susceptibility of cells lacking Pho84 to neutrophil attack depended on reactive oxygen species (ROS): pho84-/- cells were no more susceptible than wild type C. albicans to neutrophils from a patient with chronic granulomatous disease, or to those whose oxidative burst was pharmacologically inhibited or neutralized. pho84-/- mutants hyperactivated oxidative stress signalling. They accumulated intracellular ROS in the absence of extrinsic oxidative stress, in high as well as low ambient phosphate conditions. ROS accumulation correlated with diminished levels of the unique superoxide dismutase Sod3 in pho84-/- cells, while SOD3 overexpression from a conditional promoter substantially restored these cells' oxidative stress resistance in vitro. Repression of SOD3 expression sharply increased their oxidative stress hypersensitivity. Neither of these oxidative stress management effects of manipulating SOD3 transcription was observed in PHO84 wild type cells. Sod3 levels were not the only factor driving oxidative stress effects on pho84-/- cells, though, because overexpressing SOD3 did not ameliorate these cells' hypersensitivity to neutrophil killing ex vivo, indicating Pho84 has further roles in oxidative stress resistance and virulence. Measurement of cellular metal concentrations demonstrated that diminished Sod3 expression was not due to decreased import of its metal cofactor manganese, as predicted from the function of S. cerevisiae Pho84 as a low-affinity manganese transporter. Instead of a role of Pho84 in metal transport, we found its role in TORC1 activation to impact oxidative stress management: overexpression of the TORC1-activating GTPase Gtr1 relieved the Sod3 deficit and ROS excess in pho84-/- null mutant cells, though it did not suppress their hypersensitivity to neutrophil killing or hyphal growth defect. Pharmacologic inhibition of Pho84 by small molecules including the FDA-approved drug foscarnet also induced ROS accumulation. Inhibiting Pho84 could hence support host defenses by sensitizing C. albicans to oxidative stress.


Subject(s)
Candida albicans/pathogenicity , Candidiasis/metabolism , Oxidative Stress/physiology , Proton-Phosphate Symporters/metabolism , TOR Serine-Threonine Kinases/metabolism , Animals , Biological Transport/physiology , Drosophila , Fungal Proteins/metabolism , Humans , Mice , Phosphates/metabolism , Signal Transduction/physiology , Virulence
16.
EBioMedicine ; 25: 66-72, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29050948

ABSTRACT

The rapid clearance of malaria parasite DNA from circulation has widely been accepted as a fact without being systemically investigated. We assessed the persistence of parasite DNA in travelers treated for Plasmodium falciparum malaria in a malaria-free area. Venous blood was collected at the time of admission and prospectively up to one year. DNA and RNA were extracted and analyzed using species-specific and gametocyte-specific real-time PCR as well as merozoite surface protein 2 (msp2)-PCR. In 31 successfully treated individuals, asexual parasites were seen by microscopy until two days after treatment, whereas parasite DNA was detected by msp2- and species-specific PCR up to days 31 and 42, respectively. Statistical modelling predicted 26% (±0·05 SE) species-specific PCR positivity until day 40 and estimated 48days for all samples to become PCR negative. Gametocytes were detected by microscopy and PCR latest two days after treatment. CT values correlated well with microscopy-defined parasite densities before but not after treatment started. These results reveal that PCR positivity can persist several weeks after treatment without evidence of viable sexual or asexual parasites, indicating that PCR may overestimate parasite prevalence after treatment.


Subject(s)
Antigens, Protozoan/genetics , Malaria, Falciparum/diagnosis , Malaria, Falciparum/genetics , Plasmodium falciparum/genetics , Protozoan Proteins/genetics , Animals , Antigens, Protozoan/isolation & purification , Humans , Longitudinal Studies , Malaria, Falciparum/epidemiology , Malaria, Falciparum/parasitology , Plasmodium falciparum/isolation & purification , Plasmodium falciparum/pathogenicity , Polymerase Chain Reaction/methods , Protozoan Proteins/isolation & purification
17.
J Hazard Mater ; 338: 177-185, 2017 Sep 15.
Article in English | MEDLINE | ID: mdl-28551497

ABSTRACT

Spent fluid catalytic cracking (FCC) was gathered from several petrochemical plants and calcined in a rotary furnace between 1000 and 1100°C in order to remove sulphur and hydrocarbon based impurities. Calcining process on FCC led to formation of AlVO4 ceramic phase, so converted the hazardous waste to non-hazardous applicable raw material. In this study, two ceramic bodies as cordierite and cordierite-mullite were synthesized with calcined spent FCC, waste serpentine, kiln rollers waste and high grade kaolin as raw materials. The XRD results showed that the cordierite and cordierite-mullite were synthesized successfully so that 96.4% of F1 (cordierite) sample fired at 1400°C was cordierite phase and F2 (cordierite-mullite) sample fired at 1450°C was completely cordierite and mullite phases. The synthesized cordierite and cordierite-mullite samples had lower porosity values and coefficient of thermal expansion (CTE) than similar industrial products. The negative CTE value that obtained from the cordierite sample up to 800°C is favorable for some applications. The considerable results of the synthesized cordierite and cordierite-mullite from this work present cost reduction of the two ceramic bodies production and may help to solve the environmental problems with the use of three waste sources in large scales.

18.
Mutagenesis ; 32(3): 389-396, 2017 05 01.
Article in English | MEDLINE | ID: mdl-28340109

ABSTRACT

Our previous results showed that in addition to the immediate interaction of ionising radiation with DNA (direct and indirect effect), low-dose and chronic low-dose rate of irradiation induce endogenous oxidative stress. During oxidative stress, free radicals react with DNA, nucleoside triphosphates (dNTPs), proteins and lipids, and modify their structures. The MYH and MTH1 genes play important roles in preventing mutations induced by 8-hydroxy-guanine, which is an oxidised product of guanine. In this study, we used short-hairpin RNA to permanently knockdown MYH and MTH1 proteins in human lymphoblastoid TK6 cells. Knockdown and wild-type cells were chronically exposed to low dose rates of γ-radiation (between 1.4 and 30 mGy/h). The cells were also subjected to acute doses delivered at a high-dose rate. Growth rate, extracellular 8-hydroxy-2'-deoxyguanosine, clonogenic cell survival and mutant frequencies were analysed in all cell types. A reduced level of cell growth and survival as well as increased mutant frequencies were observed in cells lacking both MYH and MTH1 proteins as compared to cells lacking only MYH and wild-type cells. To sum up, our results suggest that low-dose rates elevate oxidative stress. MTH1 together with MYH plays an important role in protection against mutations induced by modified dNTPs during chronic oxidative stress. In addition, we found no dose-rate effect at the level of mutations in the wild-type TK6 and MYH-KD cells. Our data interestingly indicate a dose-rate threshold for mutation induction in MTH1/MYH double knockdown cells.


Subject(s)
DNA Damage , DNA Glycosylases/metabolism , DNA Repair Enzymes/metabolism , Deoxyguanosine/analogs & derivatives , Gamma Rays , Oxidative Stress/radiation effects , Phosphoric Monoester Hydrolases/metabolism , 8-Hydroxy-2'-Deoxyguanosine , DNA/metabolism , DNA/radiation effects , DNA Repair , Deoxyguanosine/metabolism , Humans
19.
Science ; 355(6329): 1076-1080, 2017 03 10.
Article in English | MEDLINE | ID: mdl-28183997

ABSTRACT

Malaria infection renders humans more attractive to Anopheles gambiae sensu lato mosquitoes than uninfected people. The mechanisms remain unknown. We found that an isoprenoid precursor produced by Plasmodium falciparum, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), affects A. gambiae s.l. blood meal seeking and feeding behaviors as well as susceptibility to infection. HMBPP acts indirectly by triggering human red blood cells to increase the release of CO2, aldehydes, and monoterpenes, which together enhance vector attraction and stimulate vector feeding. When offered in a blood meal, HMBPP modulates neural, antimalarial, and oogenic gene transcription without affecting mosquito survival or fecundity; in a P. falciparum-infected blood meal, sporogony is increased.


Subject(s)
Anopheles/physiology , Feeding Behavior/physiology , Malaria, Falciparum/blood , Mosquito Vectors/physiology , Organophosphates/metabolism , Plasmodium falciparum/metabolism , Animals , Anopheles/drug effects , Anopheles/genetics , Carbon Dioxide/metabolism , Erythrocytes/drug effects , Erythrocytes/metabolism , Erythrocytes/parasitology , Female , Gene Expression Regulation , Humans , Malaria, Falciparum/parasitology , Mosquito Vectors/drug effects , Mosquito Vectors/genetics , Oogenesis , Organophosphates/pharmacology , Terpenes/metabolism , Transcription, Genetic , Volatilization
20.
Sci Rep ; 7: 40520, 2017 01 17.
Article in English | MEDLINE | ID: mdl-28094293

ABSTRACT

The efficiency of malaria parasite development within mosquito vectors (sporogony) is a critical determinant of transmission. Sporogony is thought to be controlled by environmental conditions and mosquito/parasite genetic factors, with minimal contribution from mosquito behaviour during the period of parasite development. We tested this assumption by investigating whether successful sporogony of Plasmodium falciparum parasites through to human-infectious transmission stages is influenced by the host species upon which infected mosquitoes feed. Studies were conducted on two major African vector species that generally are found to differ in their innate host preferences: Anopheles arabiensis and An. gambiae sensu stricto. We show that the proportion of vectors developing transmissible infections (sporozoites) was influenced by the source of host blood consumed during sporogony. The direction of this effect was associated with the innate host preference of vectors: higher sporozoite prevalences were generated in the usually human-specialist An. gambiae s.s. feeding on human compared to cow blood, whereas the more zoophilic An. arabiensis had significantly higher prevalences after feeding on cow blood. The potential epidemiological implications of these results are discussed.


Subject(s)
Host-Parasite Interactions , Malaria/parasitology , Malaria/transmission , Mosquito Vectors/parasitology , Plasmodium , Vertebrates , Animals , Malaria/epidemiology , Parasite Load , Plasmodium falciparum , Prevalence , Salivary Glands/parasitology , Sporozoites
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