Exported proteins required for virulence and rigidity of Plasmodium falciparum-infected human erythrocytes.

A major part of virulence for Plasmodium falciparum malaria infection, the most lethal parasitic disease of humans, results from increased rigidity and adhesiveness of infected host red cells. These changes are caused by parasite proteins exported to the erythrocyte using novel trafficking machinery assembled in the host cell. To understand these unique modifications, we used a large-scale gene knockout strategy combined with functional screens to identify proteins exported into parasite-infected erythrocytes and involved in remodeling these cells. Eight genes were identified encoding proteins required for export of the parasite adhesin PfEMP1 and assembly of knobs that function as physical platforms to anchor the adhesin. Additionally, we show that multiple proteins play a role in generating increased rigidity of infected erythrocytes. Collectively these proteins function as a pathogen secretion system, similar to bacteria and may provide targets for antivirulence based therapies to a disease responsible for millions of deaths annually.

Zygote morphogenesis but not the establishment of cell polarity in Plasmodium berghei is controlled by the small GTPase, RAB11A.

Plasmodium species are apicomplexan parasites whose zoites are polarized cells with a marked apical organisation where the organelles associated with host cell invasion and colonization reside. Plasmodium gametes mate in the mosquito midgut to form the spherical and presumed apolar zygote that morphs during the following 24 hours into a polarized, elongated and motile zoite form, the ookinete. Endocytosis-mediated protein transport is generally necessary for the establishment and maintenance of polarity in epithelial cells and neurons, and the small GTPase RAB11A is an important regulator of protein transport via recycling endosomes. PbRAB11A is essential in blood stage asexual of Plasmodium. Therefore, a promoter swap strategy was employed to down-regulate PbRAB11A expression in gametocytes and zygotes of the rodent malaria parasite, Plasmodium berghei which demonstrated the essential role of RAB11A in ookinete development. The approach revealed that lack of PbRAB11A had no effect on gamete production and fertility rates however, the zygote to ookinete transition was almost totally inhibited and transmission through the mosquito was prevented. Lack of PbRAB11A did not prevent meiosis and mitosis, nor the establishment of polarity as indicated by the correct formation and positioning of the Inner Membrane Complex (IMC) and apical complex. However, morphological maturation was prevented and parasites remained spherical and immotile and furthermore, they were impaired in the secretion and distribution of microneme cargo. The data are consistent with the previously proposed model of RAB11A endosome mediated delivery of plasma membrane in Toxoplasma gondii if not its role in IMC formation and implicate it in microneme function.

Experimentally Engineered Mutations in a Ubiquitin Hydrolase, UBP-1, Modulate In Vivo Susceptibility to Artemisinin and Chloroquine in Plasmodium berghei.

As resistance to artemisinins (current frontline drugs in malaria treatment) emerges in Southeast Asia, there is an urgent need to identify the genetic determinants and understand the molecular mechanisms underpinning such resistance. Such insights could lead to prospective interventions to contain resistance and prevent the eventual spread to other regions where malaria is endemic. Reduced susceptibility to artemisinin in Southeast Asia has been primarily linked to mutations in the Plasmodium falciparum Kelch-13 gene, which is currently widely recognized as a molecular marker of artemisinin resistance. However, two mutations in a ubiquitin hydrolase, UBP-1, have been previously associated with reduced artemisinin susceptibility in a rodent model of malaria, and some cases of UBP-1 mutation variants associated with artemisinin treatment failure have been reported in Africa and SEA. In this study, we employed CRISPR-Cas9 genome editing and preemptive drug pressures to test these artemisinin susceptibility-associated mutations in UBP-1 in Plasmodium berghei sensitive lines in vivo Using these approaches, we show that the V2721F UBP-1 mutation results in reduced artemisinin susceptibility, while the V2752F mutation results in resistance to chloroquine (CQ) and moderately impacts tolerance to artemisinins. Genetic reversal of the V2752F mutation restored chloroquine sensitivity in these mutant lines, whereas simultaneous introduction of both mutations could not be achieved and appears to be lethal. Interestingly, these mutations carry a detrimental growth defect, which would possibly explain their lack of expansion in natural infection settings. Our work provides independent experimental evidence on the role of UBP-1 in modulating parasite responses to artemisinin and chloroquine under in vivo conditions.

A cascade of DNA-binding proteins for sexual commitment and development in Plasmodium.

Commitment to and completion of sexual development are essential for malaria parasites (protists of the genus Plasmodium) to be transmitted through mosquitoes. The molecular mechanism(s) responsible for commitment have been hitherto unknown. Here we show that PbAP2-G, a conserved member of the apicomplexan AP2 (ApiAP2) family of DNA-binding proteins, is essential for the commitment of asexually replicating forms to sexual development in Plasmodium berghei, a malaria parasite of rodents. PbAP2-G was identified from mutations in its encoding gene, PBANKA_143750, which account for the loss of sexual development frequently observed in parasites transmitted artificially by blood passage. Systematic gene deletion of conserved ApiAP2 genes in Plasmodium confirmed the role of PbAP2-G and revealed a second ApiAP2 member (PBANKA_103430, here termed PbAP2-G2) that significantly modulates but does not abolish gametocytogenesis, indicating that a cascade of ApiAP2 proteins are involved in commitment to the production and maturation of gametocytes. The data suggest a mechanism of commitment to gametocytogenesis in Plasmodium consistent with a positive feedback loop involving PbAP2-G that could be exploited to prevent the transmission of this pernicious parasite.

Interventions to improve adherence to exercise therapy for falls prevention in community-dwelling older adults: systematic review and meta-analysis.

BACKGROUND: exercise therapy is highly recommended for falls prevention in older adults; however, poor exercise adherence may limit treatment effectiveness. OBJECTIVE: to assess the effectiveness of interventions to improve exercise adherence for community-dwelling adults (aged over 65 years), at risk of falling. METHODS: eight databases were searched to identify randomised/quasi-randomised trials. The Capability, Opportunity, Motivation model of behaviour (COM-B) was used to categorise the identified adherence interventions. Studies with similar interventions that provided adherence outcome data per group were analysed to establish pooled intervention effect. Protocol registration with Propsero: (CRD42016033677). RESULTS: of the 20 trials included (n = 4419), five provided data per group for adherence outcome. Meta-analysis of four studies (n = 482), containing interventions exploring the way exercise is delivered, demonstrated significantly better adherence in the intervention group (n = 166 experimental, n = 161 control Fixed effects model (FEM), SMD = 0.48 95% CI [0.26-0.70] P < 0.0001 I2 = 0%, very low GRADE evidence). Within this limited evidence base, interventions using telecommunication and the integration of exercise into activities of daily living appear most promising when delivering exercise at home. Meta-analysis to explore the effect that these interventions to improve adherence had on balance (n = 166 experimental, n = 161 control Random-effects model (REM), SMD = 0.82, 95% CI [-1.20-2.84] P = 0.43 I2 = 52%) and gait (n = 59 experimental, n = 56 control REM, SMD = 0.29, 95% CI [-1.62-2.20] P = 0.77 I2 = 48%), found no statistically significant effect. CONCLUSIONS: adherence to exercise can be positively influenced; however, insufficient data exists to support any single intervention that also achieves effective outcomes for balance and gait.

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments.

Malaria parasites (Plasmodium spp.) encounter markedly different (nutritional) environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA) metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design.

Seasonal changes in body composition of inter-county Gaelic Athletic Association hurlers.

Longitudinal change in body composition for elite-level inter-county hurlers was reported over a single season and four consecutive seasons. Body composition measured by dual-energy x-ray absorptiometry (DXA) of 66 senior, male, outfield players was obtained. Four successive measurements were taken: off-season (OFF1), pre-season (PRE), mid-season (MID) and the off-season of the following season (OFF2). A subsample of 11 hurlers were measured at all time points over 4 consecutive seasons. DXA-derived estimates of fat and lean mass were normalised to stature for analysis (kg∙m‒2); data are (mean [lower: upper, 95% confidence interval]). A concurrent increase of lean mass (0.31 [0.19: 0.43] kg∙m‒2) and loss of fat mass occurred (-0.38 [-0.50: -0.26] kg∙m‒2) OFF1 to PRE. Lean mass accrual was maintained PRE to OFF2 while the initial loss of fat mass was restored MID to OFF2 (0.52 [0.40: 0.64] kg ∙ m‒2), with the trunk acting as the primary region of change. Over the four seasons, a net increase of lean mass was observed (~ 0.9 [0.4: 1.4] kg per annum) with a negligible overall change for fat mass over time. However, the cycling of fat mass (OFF to PRE and MID to OFF) within each season was recurrent season-to-season.

Body composition analysis of inter-county Gaelic athletic association players measured by dual energy X-ray absorptiometry.

Gaelic Football and Hurling are two sporting codes within the Gaelic Athletic Association. The purpose of this study was to report the body composition phenotype of inter-county Gaelic athletic association players, comparing groups by code and field position. 190 senior, male, outfield inter-county players (144 hurlers and 46 Gaelic footballers) were recruited. Stature and body mass was measured, estimates of three components of body composition, i.e., lean mass, fat mass and bone mineral content was obtained by dual energy X-ray absorptiometry (DXA), and normative data for Gaelic athletic association athletes by code and position was compared. Other than in the midfield, there was limited difference in body composition between codes or playing position. Stature-corrected indices nullified any existing group differences between midfielders for both codes. Further comparisons with a non-athletic control group (n = 431) showed no difference for body mass index (BMI); however, the athletic group has a lower fat mass index, with a greater lean mass in accounting for the matched BMI between groups. In addition to providing previously unknown normative data for the Gaelic athletic association athlete, a proportional and independent tissue evaluation of body composition is given.

Measurement tools for adherence to non-pharmacologic self-management treatment for chronic musculoskeletal conditions: a systematic review.

OBJECTIVES: To identify measures of adherence to nonpharmacologic self-management treatments for chronic musculoskeletal (MSK) populations; and to report on the measurement properties of identified measures. DATA SOURCES: Five databases were searched for all study types that included a chronic MSK population, unsupervised intervention, and measure of adherence. STUDY SELECTION: Two independent researchers reviewed all titles for inclusion using the following criteria: adult (>18y) participants with a chronic MSK condition; intervention, including an unsupervised self-management component; and measure of adherence to the unsupervised self-management component. DATA EXTRACTION: Descriptive data regarding populations, unsupervised components, and measures of unsupervised adherence (items, response options) were collected from each study by 1 researcher and checked by a second for accuracy. DATA SYNTHESIS: No named or referenced adherence measurement tools were found, but a total of 47 self-invented measures were identified. No measure was used in more than a single study. Methods could be grouped into the following: home diaries (n=31), multi-item questionnaires (n=11), and single-item questionnaires (n=7). All measures varied in type of information requested and scoring method. The lack of established tools precluded quality assessment of the measurement properties using COnsensus-based Standards for the selection of health Measurement INstruments methodology. CONCLUSIONS: Despite the importance of adherence to self-management interventions, measurement appears to be conducted on an ad hoc basis. It is clear that there is no consistency among adherence measurement tools and that the construct is ill-defined. This study alerts the research community to the gap in measuring adherence to self-care in a rigorous and reproducible manner. Therefore, we need to address this gap by using credible methods (eg, COnsensus-based Standards for the selection of health Measurement INstruments guidelines) to develop and evaluate an appropriate measure of adherence for self-management.

Plasmodium falciparum artemisinin resistance: something gained in translation.

Small-Saunders et al. uncovered a new facet of artemisinin resistance in Plasmodium in which parasites use a previously underexplored arm of stress response mechanisms. Through altered epitranscriptomic modifications on tRNA, changed translation patterns adapt resistant cells to facilitate entry into a quiescent-like state which provides the parasite an escape from many drugs.

Sleep Quality Should Be Assessed in Inpatient Rehabilitation Settings: A Preliminary Study.

OBJECTIVES: In this preliminary, longitudinal study, our objective was to assess changes in sleep quality during an inpatient stay in a rehabilitation setting in the United States and to relate changes to patients' demographic and clinical characteristics (i.e., age, gender, BMI, ethnicity, reason for hospitalization, pre-hospital living setting, prior diagnosis of sleep disorders, and mental health status). METHODS: A total of 35 patients participated in this preliminary study (age = 61 ± 16 years old, 50% <65; BMI = 30 ± 7 kg/m2; 51% female; 51% Caucasian). The average length of hospitalization was 18 ± 8 days. Reasons for hospitalization included orthopedic-related issues (28%), spinal cord injury (28%), stroke (20%), and other (23%). In this sample, 23% had prior sleep disorders (mostly sleep apnea), and 60% came from an acute care unit. Patients' sleep quality was assessed using the Pittsburgh sleep quality index (PSQI) at admission and before discharge. Demographic and medical data were collected. Patients' mental health status was also assessed at the same intervals. Nighttime sound levels and the average number of sleep disturbances were also collected throughout the study (6 months). RESULTS: Our data revealed that most patients had poor sleep (PSQI > 5) at admission (86%) and discharge (80%). Using a repeated ANOVA, a significant interaction was obtained between sleep quality and the presence of a diagnosed sleep disorder [F (1, 33) = 12.861, p = 0.001, η2p = 0.280]. The sleep quality of patients with sleep disorders improved over their stay, while the sleep of patients without such disorders did not. The mean nighttime sound collection level averages and peaks were 62.3 ± 5.1 dB and 86.1 ± 4.9 dB, respectively, and the average number of sleep disturbances was 2.6 ± 1.1. CONCLUSION: The improved sleep observed in patients with vs. without sleep disorders might be related to the care received for treating such disorders over the stay. Our findings call for the better detection and management of poor sleep in acute inpatient rehabilitation settings. Furthermore, if our findings are replicated in the future, studies on the implementation of quiet times for medical staff, patients, and family should be performed to improve sleep quality in the inpatient rehabilitation setting.

Investigation of the potential of biocalorimetry as a process analytical technology (PAT) tool for monitoring and control of Crabtree-negative yeast cultures.

Biological reaction calorimetry, also known as biocalorimetry, has led to extensive applications in monitoring and control of different bioprocesses. A simple real-time estimator for biomass and growth rate was formulated, based on in-line measured metabolic heat flow values. The performance of the estimator was tested in a unique bench-scale calorimeter (BioRC1), improved to a sensitivity range of 8 mW l(-1) in order to facilitate the monitoring of even weakly exothermic biochemical reactions. A proportional-integral feedback control strategy based on these estimators was designed and implemented to control the growth rate of Candida utilis, Kluyveromyces marxianus and Pichia pastoris by regulating an exponential substrate feed. Maintaining a particular specific growth rate throughout a culture is essential for reproducible product quality in industrial bioprocesses and therefore a key sequence for the step from quality by analysis to quality by design. The potential of biocalorimetry as a reliable biomass monitoring tool and as a key part of a robust control strategy for aerobic fed-batch cultures of Crabtree-negative yeast cells in defined growth medium was investigated. Presenting controller errors of less than 4% in the best cases, the approach paves the way for the development of a generally applicable process analytical technology platform for monitoring and control of microbial fed-batch cultures.

Significant deterioration in quality of life and increased frailty in patients waiting more than six months for total hip or knee arthroplasty : a cross-sectional multicentre study.

AIMS: The primary aim of this study was to assess whether patients waiting six months or more for a total hip (THA) or knee (KA) arthroplasty had a deterioration in their health-related quality of life (HRQoL). Secondary aims were to assess changes in frailty and the number of patients living in a state considered to be worse than death (WTD), and factors associated with changes in HRQoL and frailty. METHODS: This cross-sectional study included 326 patients, 150 males (46.0%) and 176 females (54.0%), with a mean age of 68.6 years (SD 9.8) who were randomly selected from waiting lists at four centres and had been waiting for six months or more (median 13 months, interquartile range 10 to 21) for a primary THA (n = 161) or KA (n = 165). The EuroQol five-dimension questionnaire (EQ-5D) and visual analogue scores (EQ-VAS), Rockwood Clinical Frailty Scale (CFS), and 36-Item Short Form Survey subjective change in HRQoL were assessed at the time and recalled for six months earlier. A state that was WTD was defined as an EQ-5D of less than zero. RESULTS: There were significant deteriorations in the EQ-5D (mean 0.175, 95% confidence interval (CI) 0.145 to 0.204; p < 0.001), EQ-VAS (mean 8.6, 95% CI 7.0 to 10.4; < 0.001), and CFS (from 3 "managing well" to 4 "vulnerable"; p < 0.001), and a significant increase in the number of those in a state that was WTD (n = 48; p < 0.001) during the previous six months for the whole cohort. A total of 110 patients (33.7%) stated that their health was much worse and 107 (32.8%) felt it was somewhat worse compared with six months previously. A significantly greater EQ-5D (-0.14, 95% CI 0.08 to 0.28; p = 0.038) and a state that was not WTD (-0.14, 95% CI 0.01 to 0.26; p = 0.031) were associated with a deterioration in the EQ-5D. THA (0.21, 95% CI 0.07 to 0.34; p = 0.002) or a lower (better) CFS (0.14, 95% CI 0.07 to 0.20; p < 0.001) were independently significantly associated with a deterioration in the CFS. CONCLUSION: Patients waiting more than six months for THA or KA had a significant deterioration in their HRQoL and increased frailty, with two-thirds of patients feeling that their health had worsened.Cite this article: Bone Joint J 2022;104-B(11):1215-1224.

Mammalian Deubiquitinating Enzyme Inhibitors Display in Vitro and in Vivo Activity against Malaria Parasites and Potentiate Artemisinin Action.

The ubiquitin proteasome system (UPS) is an emerging drug target in malaria due to its essential role in the parasite's life cycle stages as well its contribution to resistance to artemisinins. Polymorphisms in the Kelch13 gene of Plasmodium falciparum are primary markers of artemisinin resistance and among other things are phenotypically characterized by an overactive UPS. Inhibitors targeting the proteasome, critical components of the UPS, display activity in malaria parasites and synergize artemisinin action. Here we report the activity of small molecule inhibitors targeting mammalian deubiquitinating enzymes, DUBs (upstream UPS components), in malaria parasites. We show that generic DUB inhibitors can block intraerythrocytic development of malaria parasites in vitro and possess antiparasitic activity in vivo and can be used in combination with additive to synergistic effect. We also show that inhibition of these upstream components of the UPS can potentiate the activity of artemisinin in vitro as well as in vivo to the extent that artemisinin resistance can be overcome. Combinations of DUB inhibitors anticipated to target different DUB activities and downstream proteasome inhibitors are even more effective at improving the potency of artemisinins than either inhibitors alone, providing proof that targeting multiple UPS activities simultaneously could be an attractive approach to overcoming artemisinin resistance. These data further validate the parasite UPS as a target to both enhance artemisinin action and potentially overcome resistance. Lastly, we confirm that DUB inhibitors can be developed into in vivo antimalarial drugs with promise for activity against all of human malaria and could thus further exploit their current pursuit as anticancer agents in rapid drug repurposing programs.

Variations in arterial pedal circulation in idiopathic congenital talipes equinovarus: a systematic review.

Variations in pedal circulation in congenital talipes equinovarus (CTEV) are well documented. There is a reported risk of vascular injury to the posterior tibial artery (PTA) during operative procedures for CTEV, potentially leading to necrosis and amputation. The aim of this systematic review was to identify the most common anomalies in arterial pedal circulation in CTEV and to determine the relevance of these to clinical practice. The systematic review was registered on PROSPERO and was carried out according to Preferred Reporting Items for Systematic Reviews and Meta Analyses guidelines by two independent reviewers. Studies that examined pedal circulation in idiopathic CTEV were included. Articles that studied nonidiopathic CTEV and those not published in English were excluded. Data extracted included patient demographics, imaging modalities, and findings. A total of 14 articles satisfied the inclusion criteria, including 192 patients (279 clubfeet), aged 0-13.5 years, at various stages in their treatment. Imaging modalities included arteriography (n = 5), duplex ultrasound (n = 5), magnetic resonance angiography (n = 2), and direct visualization intraoperatively (n = 2). The dorsalis pedis was most frequently reported as absent (21.5%), and the anterior tibial artery (ATA) was most frequently reported as hypoplastic (18.3%). Where reported (n = 36 feet), 61% of patients were noted to have a dominant supply from the PTA. The most common variation in pedal circulation in CTEV is diminished supply from ATA and dorsalis pedis, although there are documented anomalies in all of the vessels supplying the foot. We therefore recommend routine Doppler ultrasound imaging prior to operative intervention in CTEV.

Characteristics and attitudes of first round invitees in the Irish National Colorectal Cancer Screening Programme.

Background/objective: Colorectal cancer (CRC) screening is proven to reduce CRC-related mortality. Faecal immunochemical testing (FIT)-positive clients in the Irish National CRC Screening Programme underwent colonoscopy. Round 1 uptake was 40.2%. We sought to identify barriers to participation by assessing knowledge of CRC screening and examining attitudes towards FIT test and colonoscopy. Methods: Questionnaires based on a modified Champion's Health Belief Model were mailed to 3500 invitees: 1000 FIT-positive, 1000 FIT-negative and 1500 non-participants. 44% responded: 550 (46%) FIT-positive, 577 (48%) FIT-negative and 69 (6%) non-responders (NR). Results: 25% of respondents (n=286) did not perceive a personal risk of cancer, did not perceive CRC to be a serious disease and did not perceive benefits to screening. These opinions were more likely to be expressed by men (p=0.035). One-fifth (n=251) found screening stressful. Fear of cancer diagnosis and test results were associated with stress. FIT-positive clients, women and those with social medical insurance were more likely to experience stress. Conclusions: The CRC screening process causes stress to one-fifth of participants. Greater use of media and involvement of healthcare professionals in disseminating information on the benefits of screening may lead to higher uptake in round 2.

A systematic review of reported outcomes following Ponseti correction of idiopathic club foot.

AIMS: To analyze outcomes reported in studies of Ponseti correction of idiopathic clubfoot. METHODS: A systematic review of the literature was performed to identify a list of outcomes and outcome tools reported in the literature. A total of 865 studies were screened following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and 124 trials were included in the analysis. Data extraction was completed by two researchers for each trial. Each outcome tool was assigned to one of the five core areas defined by the Outcome Measures Recommended for use in Randomized Clinical Trials (OMERACT). Bias assessment was not deemed necessary for the purpose of this paper. RESULTS: In total, 20 isolated outcomes and 16 outcome tools were identified representing five OMERACT domains. Most outcome tools were appropriately designed for children of walking age but have not been embraced in the literature. The most commonly reported isolated outcomes are subjective and qualitative. The quantitative outcomes most commonly used are ankle range of motion (ROM), foot position in standing, and muscle function. CONCLUSIONS: There is a diverse range of outcomes reported in studies of Ponseti correction of clubfoot. Until outcomes can be reported unequivocally and consistently, research in this area will be limited. Completing the process of establishing and validating COS is the much-needed next step.Cite this article: Bone Joint Open 2020;1-8:457-464.

Plasmodium gametocytes display homing and vascular transmigration in the host bone marrow.

Transmission of Plasmodium parasites to the mosquito requires the formation and development of gametocytes. Studies in infected humans have shown that only the most mature forms of Plasmodium falciparum gametocytes are present in circulation, whereas immature forms accumulate in the hematopoietic environment of the bone marrow. We used the rodent model Plasmodium berghei to study gametocyte behavior through time under physiological conditions. Intravital microscopy demonstrated preferential homing of early gametocyte forms across the intact vascular barrier of the bone marrow and the spleen early during infection and subsequent development in the extravascular environment. During the acute phase of infection, we observed vascular leakage resulting in further parasite accumulation in this environment. Mature gametocytes showed high deformability and were found entering and exiting the intact vascular barrier. We suggest that extravascular gametocyte localization and mobility are essential for gametocytogenesis and transmission of Plasmodium to the mosquito.