Secondary Parasite Research Articles

Impact of planting and harvest dates on yam infestation by white grubs

AbstractThe white grub, Diaprepes abbreviatus L. (Coleoptera: Curculionidae), is a significant pest of yam tubers and the second cause of tuber rot in Haiti. Larval feeding inflicts severe damage to tubers, leading to notable losses due to decreased tuber quality, reduced marketability and increased susceptibility to secondary parasites and pathogens. This study examined the influence of planting and harvesting dates on the vulnerability of yam tubers to white grub infestation and the resulting tuber quality across 24 farmers' fields. At harvest, we assessed the level of tuber infestation, white grub density and the tuber quality index. The results indicated that 85% of grub populations were found in fields planted on the traditional date. In addition, 69.5% of tuber damage occurred in early‐planted fields with fewer tubers damaged (30%) when harvested early. In contrast, in fields planted 30 days after the traditional date, the harvest date did not affect tuber infestation and damage by the pest. Overall, both planting and harvest dates impacted the quality grade of yam tubers. Delayed planting by 30 days and early harvesting (34th–38th week after planting) improved the marketability of yams. These findings highlight the importance of optimising planting and harvest schedules to better manage white grub infestation and enhance the marketability of yam tubers.

Expression of IL-10 and TGF-β1 in horses experimentally infected with T. equi merozoites is associated with antibody production but not modulation of pro-inflammatory responses.

Theileria equi (T. equi) is an apicomplexan parasite that causes severe hemolytic anemia in equids. Presently, there is inadequate knowledge of the immune responses induced by T. equi in equid hosts impeding understanding of the host parasite relationship and development of potent vaccines for control of T. equi infections. The objective of this study was to evaluate the host-parasite dynamics between T. equi merozoites and infected horses by assessing cytokine expression during primary and secondary parasite exposure, and to determine whether the pattern of expression correlated with clinical indicators of disease. Our findings showed that the expression of pro-inflammatory cytokines was very low and inconsistent during both primary and secondary infection. There was also no correlation between the symptoms observed during primary infection and expression of the cytokines. This suggests that the symptoms might have occurred primarily due to hemolysis and likely not the undesirable effects of pro-inflammatory responses. However, IL-10 and TGF-β1 were highly expressed in both phases of infection, and their expression was linked to antibody production but not moderation of pro-inflammatory cytokine responses.

Phosphorescence and Potential Antibiosis Secondary to Photorhabdus Luminescens Wound Contaminations at the Battle of Shiloh, Tennessee 1862

During the American Civil War, contemporary accounts describe a peculiar luminescence phenomenon associated with untreated injuries sustained by fallen troops after the Battle of Shiloh (6-7 April 1862). While not experienced by all soldiers, field surgeons observed that the glow was somehow linked to reduced rates of wound infection and better outcomes. Given the wet springtime weather and unsheltered overnight conditions of the injured, it is plausible that some lacerations or punctures were incidentally infected with microscopic contaminants, including common soil nematodes. One endemic group likely present on riverbank groundcover is fam. Heterorhabditidae, a symbiotic host to Photorhabdus luminescens. Classified within the Morganellaceae, this Gram-negative pathogen is characterized by its unusual life cycle. With particular relevance to Shiloh, this sequence includes a blue-green phosphorescence phase accompanied by release of protein toxins having local antibiotic properties. Here, natural progression of this microbe from nematode symbiont to lethal secondary insect parasite lodged in an unclean wound is considered. Photorhabdus life-cycle is discussed as a component of the Martin-Curtis Hypothesis (2001), with new information on fluorophore isolation and recent genomic sequencing data. The Shiloh campaign is also placed within the context of the larger Western Theatre, noting that the engagement marked the heaviest Civil War casualty toll up to that point.

Unreported mixed Plasmodium species infection may increase vivax malaria in India: a challenge for malaria elimination.

In India, there are several malaria-endemic regions where non-falciparum species coexist with Plasmodium falciparum. Traditionally, microscopy and rapid diagnostic tests are used for the diagnosis of malaria. Nevertheless, microscopy often misses the secondary malaria parasite in mixed-infection cases due to various constraints. Misdiagnosis/misinterpretation of Plasmodium species leads to improper treatment, as the treatment for P. falciparum and Plasmodium vivax species is different, as per the national vector-borne disease control program in India. Blood samples were collected from malaria-endemic regions (Jharkhand, Madhya Pradesh, Chhattisgarh, Maharashtra, Odisha, Assam, Meghalaya, Mizoram and Telangana) of India covering almost the entire country. Molecular diagnosis of Plasmodium species was carried out among microscopically confirmed P. falciparum samples collected during a therapeutic efficacy study in different years. The polymerase chain reaction analysis revealed a high prevalence (18%) of mixed malaria parasite infections among microscopically confirmed P. falciparum samples from malaria patients that are either missed or left out by microscopy. Deployment of molecular tools in areas of mixed species infection may prove vital for accurate diagnosis and treatment of malaria. Further, it will help in achieving the goal of malaria elimination in India.

Equal contributions of feline immunodeficiency virus and coinfections to morbidity in African lions.

Feline immunodeficiency virus (FIV) is a pathogenic lentivirus related to human and simian immunodeficiency viruses that has been associated with AIDS-like pathologies in domestic and wild cats, as well as in hyenas. Despite known pathologies, progressive immunosuppression and ill health effects driven by these lentiviruses in association with other secondary infections remain understudied in free-ranging species. Here, the role of coinfections by gastrointestinal parasites and tick-borne hemoparasites for FIV disease progression was explored in 195 free-ranging African lions (Panthera leo) living in Kruger National Park (KNP), South Africa. Using statistical methodology, we evaluated the effects of FIV on a range of health indicators to explore how direct and indirect effects of FIV and associated coinfections align to determine lion health outcomes. Findings show direct negative effects of FIV on host immunity and nutritional status, and exacerbation of aggressive behaviors, conditions which may increase exposure/susceptibility to other secondary infections. When taken together, the contribution of coinfecting parasites to morbidity in lions is of similar magnitude as direct effects of FIV infection alone, suggesting that the particular coinfection assemblage may play a role in mediating disease progression within natural lion populations.

The application of community ecology theory to co-infections in wildlife hosts.

Priority effect theory, a foundational concept from community ecology, states that the order and timing of species arrival during species assembly can affect species composition. Although this theory has been applied to co-infecting parasite species, it has almost always been with a single time lag between co-infecting parasites. Thus, how the timing of parasite species arrival affects co-infections and disease remains poorly understood. To address this gap in the literature, we exposed postmetamorphic Cuban tree frogs (Osteopilus septentrionalis) to Ranavirus, the fungus Batrachochytrium dendrobatidis (Bd), a nematode Aplectana hamatospicula, or pairs of these parasites either simultaneously or sequentially at a range of time lags and quantified load of the secondary parasite and host growth, survival, and parasite tolerance. Prior exposure to Bd or A. hamatospicula significantly increased viral loads relative to hosts singly infected with Ranavirus, whereas A. hamatospicula loads in hosts were higher when coexposed to Bd than when coexposed to Ranavirus. There was a significant positive relationship between time since Ranavirus infection and Bd load, and prior exposure to A. hamatospicula decreased Bd loads compared to simultaneous co-infection with these parasites. Infections with Bd and Ranavirus either singly or in co-infections decreased host growth and survival. This research reveals that time lags between co-infections can affect parasite loads, in line with priority effects theory. As co-infections in the field are unlikely to be simultaneous, an understanding of when co-infections are impacted by time lags between parasite exposures may play a major role in controlling problematic co-infections.

Geophagy in the yellow-tailed woolly monkey (Lagothrix flavicauda) at La Esperanza, Peru: site characterization and soil composition.

Geophagy is the intentional consumption of soil and has been observed in various animal taxa including human and nonhuman primates. Among the numerous adaptive hypotheses proposed to explain this behavior, two of them stand out: soil either protects the gastrointestinal tract from secondary plant compounds, parasites and pathogens, and/or supplements micronutrients in the diet. Few studies have characterized the physical and chemical characteristics of soils consumed by nonhuman primates. Here, we describe the composition of soils consumed by yellow-tailed woolly monkeys (Lagothrix flavicauda) in comparison with soils taken from surrounding areas. We also studied the physical aspects of geophagy sites in terms of accessibility, dimensions and vegetation density. This study took place at the La Esperanza field site, in northern Peru, between 2016 and 2018. We conducted focal follows, placed camera traps at geophagy sites and sampled soils. In total, we recorded 77 geophagy events. Our results highlight some aspects of soil and site selection in these arboreal primates, who face an increased predation risk when descending to the ground. Animals preferred smaller sites with denser surrounding vegetation. Composition of consumed soils was similar between geophagy sites. Soils were poor in micronutrients, but contained around 20% clay. High clay content, coupled with the fact that geophagy was performed significantly more in the dry season, when leaf consumption is highest, lends support to geophagy as a mechanism for protection of the gastrointestinal tract in L. flavicauda.

ANTI-ASIALO GM1 TREATMENT DURING SECONDARY TOXOPLASMA GONDII INFECTION IS LETHAL AND DEPLETES T CELLS

Abstract Anti-NK1.1 and anti-Asialo GM1 (ASGM1) antibodies are used to deplete NK cells. Many antibody depletion strategies in vivo can have off-target effects. In a vaccine challenge model of T. gondii infection, we observed treatment of mice with these antibodies resulted in different survival outcomes after lethal secondary infection. Anti-ASGM1 resulted in 100% death and greater parasite burden at the site of infection than anti-NK1.1 treatment. We also found that anti-ASGM1 treatment depleted T cells. While both CD8+ and CD4+ T cells were affected, CD8+ T cells were more susceptible to the anti-ASGM1 treatment. Surface ASGM1 of the T cells was expressed on a higher percentage of CD8+ T cells than CD4+ T cells. Not all CD8+ T cells expressed ASGM1. In immunized mice ASGM1 was highly enriched on the surface of effector memory (Tem) and central memory (Tcm) CD8+ T cells, with a greater effect on Tem cells. After secondary parasite challenge, Tem, Tcm, effector (Tef) and naïve (Tn) CD8+ T cells were positive for ASGM1. Anti-ASGM1 treatment during rechallenge resulted in greater depletion of activated IFNγ+, Granzyme B+, Tem and Tef than Tcm and Tn CD8+ T cells. In addition, anti-ASGM1 depleted IFNγ+ CD4+ T cells. Recombinant IFNγ supplementation prolonged the survival of anti-ASGM1 treated mice, demonstrating that anti-ASGM1 eliminated IFNγ-producing T and NK cells important for control of the parasite. Our results thus highlight that anti-ASGM1 is not an optimal choice for targeting only NK cells and more precise approaches should be used to target them. This study also uncovers ASGM1 as a marker of activated effector T cells and the potential importance of changes in sialylation in lipid rafts for T cell activation during T. gondii infection.

THE IL-12- AND IL-23-DEPENDENT NK-CELL RESPONSE IS ESSENTIAL FOR PROTECTIVE IMMUNITY AGAINST SECONDARY TOXOPLASMA GONDII INFECTION

Abstract Natural Killer (NK) cells can develop memory-like features and contribute to long-term immunity in mice and humans. NK cells are critical for protection against acute T. gondii infection. However, whether they contribute to long-term immunity in response to this parasite is unknown. We used a vaccine challenge model of parasite infection to address this question and to define the mechanism by which NK cells are activated during secondary parasite infection. We found NK cells were required for control of secondary infection. NK cells increased in number at the infection site, became cytotoxic and produced IFNγ. Adoptive transfer and NK-cell fate mapping revealed that T. gondii-experienced NK cells were not intrinsically different from naïve NK cells with respect to their long-term persistence and ability to protect. Thus, they did not develop memory-like characteristics. Instead, a cell-extrinsic mechanism may control protective NK-cell responses during secondary infection. To test the involvement of a cell-extrinsic mechanism, we used anti-IL-12p70 depletion and IL-12p35−/− mice and found that the secondary NK-cell response was not fully dependent on IL-12. IL-23 depletion with anti-IL-23p19 in vivo significantly reduced the secondary NK-cell response, suggesting that both IL-12 and IL-23 were involved. Anti-IL-12p40 treatment, which blocks both IL-12 and IL-23, eliminated the protective secondary NK-cell response, supporting this hypothesis. Our results define a previously unknown protective role for NK cells during secondary T. gondii infection that is dependent on both IL-12 and IL-23.

IL-12 and IL-23 dependent NK cell response is essential for protective immunity against secondary Toxoplasma gondii infection

Abstract Natural Killer (NK) cells can develop memory-like features and contribute to long term-immunity in mice and humans in response to viral infections. NK cells are critical for protecting against acute T. gondii infection. How they impact long-term immunity in response to the parasite and mechanism(s) involved is unknown. Using a vaccine-challenge model of parasite infection we addressed these questions. After lethal reinfection of vaccinated mice with or without NK cells, we find they are required for immune control of secondary parasite infection. Unexpectedly, secondary responses of CD4 and CD8 T cells are also reduced in the absence of NK cells during reinfection of vaccinated mice. NK cells mount a secondary response noted by increased IFNγ production, however, adoptive transfer and NK cell fate mapping reveal that T. gondii-experienced cells are not intrinsically different from naïve cells in persistence and ability to protect. This suggests a cell extrinsic mechanism controls protective NK cell response during secondary infection. Although NK cell IFNg is IL-12 dependent during acute T. gondii infection, using anti-IL-12p70 antibody or IL-12p35−/− mice we find that secondary NK cell response is not fully dependent upon IL-12. IL-23 depletion with anti-IL-23p19 in vivo also significantly reduces the secondary NK cell response suggesting both IL-12 and IL-23 are involved. Anti-IL-12p40 treatment, which blocks both IL-12 and IL-23, completely eliminates protective secondary NK cell response, supporting this hypothesis. These results identify a previously unknown protective role of NK cells during secondary T. gondii infection that is not only IL-12 dependent, but also requires IL-23 and may involve an interaction with T cells.

Plasmodium falciparum variant erythrocyte surface antigens: a pilot study of antibody acquisition in recurrent natural infections

BackgroundDuring intra-erythrocytic replication Plasmodium falciparum escapes the human host immune system by switching expression of variant surface antigens (VSA). Piecemeal acquisition of variant specific antibody responses to these antigens as a result of exposure to multiple re-infections has been proposed to play a role in acquisition of naturally acquired immunity.MethodsImmunofluorescence was used to explore the dynamics of anti-VSA IgG responses generated by children to (i) primary malaria episodes and (ii) recurrent P. falciparum infections.ResultsConsistent with previous studies on anti-VSA responses, sera from each child taken at the time of recovery from their respective primary infection tended to recognize their own secondary parasites poorly. Additionally, compared to patients with reinfections by parasites of new merozoite surface protein 2 (MSP2) genotypes, baseline sera sampled from patients with persistent infections (recrudescence) tended to have higher recognition of heterologous parasites. This is consistent with the prediction that anti-VSA IgG responses may play a role in promoting chronic asymptomatic infections.ConclusionsThis pilot study validates the utility of recurrent natural malaria infections as a functional readout for examining the incremental acquisition of immunity to malaria.

Effects of a crustacean parasite and hyperparasite on the Japanese spiny oyster Saccostrea kegaki

Parasitism is one of the most common interspecific interactions, but little information exists on the detailed relationships among hosts, parasites, and hyperparasites (secondary parasites) in marine ecosystems. Pea crabs parasitize a wide variety of marine animals, and the crabs themselves are often parasitized by other animals. The present study investigated the relationships among the oyster Saccostrea kegaki, its parasite, the pea crab Pinnotheres boninensis, and a hyperparasite, the isopod Onychocepon resupinum. Field sampling was conducted during the oyster’s reproductive season (June–September 2014 and 2015) to evaluate effects of the pea crab on the body weight, maturation, and sex of the oyster in western Japan (Banshozaki, Shirahama Town, Wakayama Pref.; 33.41°N, 135.20°E). The relationship between the pea crab and the isopod and indirect effects of the isopod on the oyster were also investigated. The pea crab reduced the oyster’s body weight and affected its reproduction: the proportion of mature individuals was lower in infested oysters (39.1%) than in non-infested ones (86.2%). The isopod affected the crab’s sexual characteristics: infested female crabs had poorly developed ovaries, and infested males showed degrees of feminization and increased body size. The prevalence of the isopod was much higher in male (47.1%) than female (6.4%) crabs inside the oyster shells, suggesting that the parasitized male crabs became larger and were forced to remain inside the shells. Therefore, the isopod appears to have an indirect negative impact on the oyster by changing the male crab’s traits.

Zur Frage der direkten oder indirekten Schädigung von Rebenwurzeln bei Befall durch die Reblaus ( Dactylosphaera vitifolii Shimer)

Is damage of phylloxera infested grapevine roots caused directly or indirectly? Disinfected eggs of phylloxera ( Dactylosphaera vitifolii SHIMER) were transferred to rooted explants of Vitis vinifera shoots (cv. Silvaner) reared under sterile conditions. Aerial rootlets which showed injuries in consequence of the insect's infestation proved to be free of microorganisms. lt is concluded, therefore, that damage of grapevine roots is pr imarily due to the activity of phylloxera itself, especially to abnormous growth and disturbance of metabolism in the affected plant tissues. Microorganisms occurring in root galls of naturally growing vines are considered to be secondary parasites or saprophytes.

Concomitant Immunity Induced by Persistent Leishmania major Does Not Preclude Secondary Re-Infection: Implications for Genetic Exchange, Diversity and Vaccination.

BackgroundMany microbes have evolved the ability to co-exist for long periods of time within other species in the absence of overt pathology. Evolutionary biologists have proposed benefits to the microbe from ‘asymptomatic persistent infections’, most commonly invoking increased likelihood of transmission by longer-lived hosts. Typically asymptomatic persistent infections arise from strong containment by the immune system, accompanied by protective immunity; such ‘vaccination’ from overt disease in the presence of a non-sterilizing immune response is termed premunition or concomitant immunity. Here we consider another potential benefit of persistence and concomitant immunity to the parasite: the ‘exclusion’ of competing super-infecting strains, which would favor transmission of the original infecting organism.Methodology / Principle FindingsTo investigate this in the protozoan parasite Leishmania major, a superb model for the study of asymptomatic persistence, we used isogenic lines of comparable virulence bearing independent selectable markers. One was then used to infect genetically resistant mice, yielding infections which healed and progressed to asymptomatic persistent infection; these mice were then super-infected with the second marked line. As anticipated, super-infection yielded minimal pathology, showing that protective immunity against disease pathology had been established. The relative abundance of the primary and super-infecting secondary parasites was then assessed by plating on selective media. The data show clearly that super-infecting parasites were able to colonize the immune host effectively, achieving numbers comparable to and sometimes greater than that of the primary parasite.Conclusions / SignificanceWe conclude that induction of protective immunity does not guarantee the Leishmania parasite exclusive occupation of the infected host. This finding has important consequences to the maintenance and generation of parasite diversity in the natural Leishmania infectious cycle alternating between mammalian and sand fly hosts.

Variable effects of nicotine, anabasine, and their interactions on parasitized bumble bees.

Secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. Previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. We tested for interactions between the effects of two alkaloids found in the nectar of Nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( Bombus impatiens) infected with the intestinal parasite Crithidia bombi. Adult worker bees inoculated with C. bombi were fed nicotine and anabasine diet treatments in a factorial design, resulting in four nectar treatment combinations: 2 ppm nicotine, 5 ppm anabasine, 2ppm nicotine and 5 ppm anabasine together, or a control alkaloid-free solution. We conducted the experiment twice: first, with bees incubated under variable environmental conditions ('Variable'; temperatures varied from 10-35°C with ambient lighting); and second, under carefully controlled environmental conditions ('Stable'; 27°C incubator, constant darkness). In 'Variable', each alkaloid alone significantly decreased parasite loads, but this effect was not realized with the alkaloids in combination, suggesting an antagonistic interaction. Nicotine but not anabasine significantly increased mortality, and the two compounds had no interactive effects on mortality. In 'Stable', nicotine significantly increased parasite loads, the opposite of its effect in 'Variable'. While not significant, the relationship between anabasine and parasite loads was also positive. Interactive effects between the two alkaloids on parasite load were non-significant, but the pattern of antagonistic interaction was similar to that in the variable experiment. Neither alkaloid, nor their interaction, significantly affected mortality under controlled conditions. Our results do not indicate synergy between Nicotiana nectar alkaloids; however, they do suggest a complex interaction between secondary metabolites, parasites, and environmental variables, in which secondary metabolites can be either toxic or medicinal depending on context.

Variable effects of nicotine, anabasine, and their interactions on parasitized bumble bees

Secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. Previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. We tested for interactions between the effects of two alkaloids found in the nectar of Nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( Bombus impatiens) infected with the intestinal parasite Crithidia bombi. Adult worker bees inoculated with C. bombi were fed nicotine and anabasine diet treatments in a factorial design, resulting in four nectar treatment combinations: 2 ppm nicotine, 5 ppm anabasine, 2ppm nicotine and 5 ppm anabasine together, or a control alkaloid-free solution. We conducted the experiment twice: first, with bees incubated under variable environmental conditions (‘Variable’; temperatures varied from 10-35°C with ambient lighting); and second, under carefully controlled environmental conditions (‘Stable’; 27°C incubator, constant darkness). In ‘Variable’, each alkaloid alone significantly decreased parasite loads, but this effect was not realized with the alkaloids in combination, suggesting an antagonistic interaction. Nicotine but not anabasine significantly increased mortality, and the two compounds had no interactive effects on mortality. In ‘Stable’, nicotine significantly increased parasite loads, the opposite of its effect in ‘Variable’. While not significant, the relationship between anabasine and parasite loads was also positive. Interactive effects between the two alkaloids on parasite load were non-significant, but the pattern of antagonistic interaction was similar to that in the variable experiment. Neither alkaloid, nor their interaction, significantly affected mortality under controlled conditions. Our results do not indicate synergy between Nicotiana nectar alkaloids; however, they do suggest a complex interaction between secondary metabolites, parasites, and environmental variables, in which secondary metabolites can be either toxic or medicinal depending on context.

Variable effects of nicotine and anabasine on parasitized bumble bees

Secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. Previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. We tested for synergistic effects of two alkaloids found in the nectar of Nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( Bombus impatiens) infected with the intestinal parasite Crithidia bombi. Adult worker bees inoculated with C. bombi were fed nicotine and anabasine diet treatments in a factorial design, resulting in four nectar treatment combinations: 2 ppm nicotine, 5 ppm anabasine, 2ppm nicotine and 5 ppm anabasine together, or a control alkaloid-free solution. We conducted the experiment twice: first, with bees incubated under variable environmental conditions ('Variable'; temperatures varied from 10-35°C); and second, under carefully controlled environmental conditions ('Controlled'; 27°C incubator, constant darkness). In 'Variable', each alkaloid alone significantly decreased parasite loads, but this effect was not realized with the alkaloids in combination, suggesting an antagonistic interaction. Nicotine but not anabasine significantly increased mortality, and the two compounds had no interactive effects on mortality. In 'Controlled', nicotine significantly increased parasite loads, the opposite of its effect in 'Variable'. While not significant, the relationship between anabasine and parasite loads was also positive. Interactive effects between the two alkaloids on parasite load were non-significant, but the pattern of antagonistic interaction was similar to that in the variable experiment. Neither alkaloid, nor their interaction, significantly affected mortality under controlled conditions. Our results do not indicate synergy between Nicotiana nectar alkaloids; however, they do suggest a complex interaction between secondary metabolites, parasites, and environmental variables, in which secondary metabolites can be either toxic or medicinal depending on context.

Development of a tool–work thermocouple calibration system with physical compensation to study the influence of tool-holder material on cutting temperature in machining

The main objective of this work is the experimental investigation of the influence of tool-holder material on tool–chip interface temperature and on the surface temperatures of the cutting tool and tool-holder. The study was conducted in dry machining of grey iron with uncoated cemented carbide inserts, using identical cutting parameters. Five tool-holders were made with materials having different thermal conductivity: copper, brass, aluminium, stainless steel and titanium alloy. The tool-holders are identical and have the same constructive aspects obtained from the commercial tool-holder for machining grey iron. The temperature at the tool–chip interface was measured using the tool–work thermocouple method and the surface temperatures on the insert and tool-holders, by conventional T type thermocouples. The system was modified in order to develop an experimental procedure for the physical compensation of the secondary junctions and parasite thermoelectric e.m.f. signals. Also, modifications were carried out in a conventional tail-stock to obtain the e.m.f. signal between the rotating workpiece and the stationary insert, without significantly altering the stiffness of the system. The tail-stock with mercury bearing inside was insulated electrically. The internal connections became reference junctions at room temperature; otherwise, they would act as secondary junctions. The calibration of the tool–work thermocouple was developed in the experimental apparatus using the same modifications as implemented in the system. Besides the results obtained with the investigation of the effects of the tool-holder materials on the surface temperatures of the insert and the tool-holder and the tool–chip interface temperature, this research presents also contributions to the calibration and performance of the tool–work thermocouple method with physical compensation.

IL-27 Receptor Signaling Regulates Memory CD4 + T Cell Populations and Suppresses Rapid Inflammatory Responses during Secondary Malaria Infection

Interleukin-27 (IL-27) is known to control primary CD4(+) T cell responses during a variety of different infections, but its role in regulating memory CD4(+) T responses has not been investigated in any model. In this study, we have examined the functional importance of IL-27 receptor (IL-27R) signaling in regulating the formation and maintenance of memory CD4(+) T cells following malaria infection and in controlling their subsequent reactivation during secondary parasite challenge. We demonstrate that although the primary effector/memory CD4(+) T cell response was greater in IL-27R-deficient (WSX-1(-/-)) mice following Plasmodium berghei NK65 infection than in wild-type (WT) mice, there were no significant differences in the size of the maintained memory CD4(+) T population(s) at 20 weeks postinfection in the spleen, liver, or bone marrow of WSX-1(-/-) mice compared with WT mice. However, the composition of the memory CD4(+) T cell pool was slightly altered in WSX-1(-/-) mice following clearance of primary malaria infection, with elevated numbers of late effector memory CD4(+) T cells in the spleen and liver and increased production of IL-2 in the spleen. Crucially, WSX-1(-/-) mice displayed significantly enhanced parasite control compared with WT mice following rechallenge with homologous malaria parasites. Improved parasite control in WSX-1(-/-) mice during secondary infection was associated with elevated systemic production of multiple inflammatory innate and adaptive cytokines and extremely rapid proliferation of antigen-experienced T cells in the liver. These data are the first to demonstrate that IL-27R signaling plays a role in regulating the magnitude and quality of secondary immune responses during rechallenge infections.

Non-host facilitators, a new category that unexpectedly favours parasitic weeds

In Europe, the current decrease of herbicide application increases and diversifies weed flora in crops. As a consequence, there is an increase in the number of pests that use weeds to spread. This change is a major threat to crop production. For instance broomrape—Phelipanche ramosa—is an obligate parasite of dicotyledonous species that reduces crop yield by up to 80 % of oilseed rape in France. In highly infected fields, broomrape can in turn infect various weed species and thus persist and even proliferate in the absence of host crops. Up to now, three categories of interactions between broomrape and plant species have been identified in monospecific stands: host, non-host and false host. In multispecific stands, broomrape germination and attachment have never been studied despite the use of multispecific crop associations to protect host crops with non-host species in tropical conditions. Therefore, we studied parasite germination and attachment of monospecific vs. multispecific stands, associating broomrape with host plants (oilseed rape), non-host plants (field bindweed) or a combination of both. Experiments were conducted in vitro for 6 weeks and in pots for 3 months. We measured the percentage of germinated broomrape seeds in the presence of field bindweed or oilseed rape. We analysed the attachment of the parasite on its host. Results unexpectedly show a nearly threefold increase in the infection of host oilseed rape in the presence of field bindweed. We thus proposed a new plant species category called ‘non-host facilitator’ and a new parasitic interaction process named ‘facilitation’. The underlying mechanism is still unknown though we observed that field bindweed was able to support secondary parasite attachments originating from primary attachments on a nearby oilseed rape root system. Our discovery implies the rethinking of parasite management in arable crops, particularly the rotation or association of host with non-host crops, since the non-host crops could actually be non-host facilitators.