Influence of blood meal on the responsiveness of olfactory receptor neurons in antennal sensilla trichodea of the yellow fever mosquito, Aedes aegypti

In female Aedes aegypti L. mosquitoes, a blood meal induces physiological and behavioral changes. Previous studies have shown that olfactory receptor neurons (ORNs) housed in grooved peg sensilla on the antennae of Ae. aegypti down-regulate their sensitivity to lactic acid, a key component driving host-seeking behavior, which correlates with observed changes in the host-seeking behavior of this species. In the present study, we performed electrophysiological recordings from the most abundant antennal sensillum type, sensilla trichodea. Our results indicate that the response spectra of ORNs contained within most trichoid sensilla do not change in response to blood feeding. However, we observe an increase in sensitivity to primarily indole and phenolic compounds in neurons housed within four of the five functional types of short blunt tipped II trichoid sensilla, both at 24 and 72 h post-blood feeding, which was more pronounced at 24 h than 72 h. Furthermore, sensitivity to undecanone, acetic acid and propionic acid was observed to increase 72 h post-blood meal. Considering the timing of these changes, we believe that these neurons may be involved in driving the orientation behavior of female mosquitoes to oviposition sites, which are known to release these compounds.     

Regulation of immunity to Plasmodium: Implications from mouse models for blood stage malaria vaccine design

Malaria, a disease caused by the protozoan parasite Plasmodium, remains a serious healthcare problem in developing countries worldwide. While the host-parasite relationship in humans has been difficult to determine, the pliability of murine malaria models has enabled valuable contributions to the understanding of the pathogenesis of disease. Although no single model reflects precisely malaria infection of the human, different models collectively provide important information on the mechanisms of protective immunity and immunopathogenesis. This review summarizes progress towards understanding the broad spectrum of immune responsiveness to the blood stages of the malaria parasite during experimental infections in mice and highlights how examination of murine malarias sheds light on the factors involved in the modulation of vaccine-potentiated immunity.     

A history of studies that examine the interactions of Toxoplasma with its host cell: Emphasis on in vitro models

This review is a historical look at work carried out over the past 50 years examining interactions of Toxoplasma with the host cell and attempts to focus on some of the seminal experiments in the field. This early work formed the foundation for more recent studies aimed at identifying the host and parasite factors mediating key Toxoplasma-host cell interactions. We focus especially on those studies that were performed in vitro and provide discussions of the following general areas: (i) establishment of the parasitophorous vacuole, (ii) the requirement of specific host cell molecules for parasite replication, (iii) the scenarios under which the host cell can resist parasite replication and/or persistence, (iv) host species-specific and host strain-specific responses to Toxoplasma infection, and (v) Toxoplasma-induced immune modulation.     

Toxoplasma gondii: Effects of Artemisia annua L. on susceptibility to infection in experimental models in vitro and in vivo

Considering that the treatment for toxoplasmosis is based on drugs that show limited efficacy due to their substantial side effects, the purpose of the present study was to evaluate the effects of Artemisia annua on in vitro and in vivo Toxoplasma gondii infection. A. annua infusion was prepared from dried herb and tested in human foreskin fibroblasts (HFF) or mice that were infected with the parasite and compared with sulfadiazine treatment. For in vitro experiments, treatment was done on parasite before HFF infection or on cells previously infected with T. gondii and the inhibitory concentration (IC₅₀) values for each treatment condition were determined. Viability of HFF cells in the presence of different concentrations of A. annua infusion and sulfadiazine was above 72%, even when the highest concentrations from both treatments were tested. Also, the treatment of T. gondii tachyzoites with A. annua infusion before infection in HFF cells showed a dose-response inhibitory curve that reached up to 75% of inhibition, similarly to the results observed when parasites were treated with sulfadiazine. In vivo experiments with a cystogenic T. gondii strain demonstrated an effective control of infection using A. annua infusion. In conclusion, our results indicate that A. annua infusion is useful to control T. gondii infection, due to its low toxicity and its inhibitory action directly against the parasite, resulting in a well tolerated therapeutic tool.     

Effects of plant nutrient availability and host plant species on the performance of two Pieris butterflies (Lepidoptera: Pieridae)

We assayed the interaction on the availability of plant nutrient and species of host plant on the performance of two species of Pieris butterfly. The results indicated that constant application of different levels of fertilizers to the four different host plants resulted to an increase in their content of plant nutrients. The chemical analysis showed that the added nutrients increased foliar nitrogen and water contents, but there was no effect on the level of glucosinolates. Larvae that fed on highly-nutritious foliage increased their growth rates and showed a shorter development period. The results of feeding trials revealed that the 4th-instar larvae, which had fed on host plants with higher levels of fertilization had a shorter duration of development, less consumption rate, higher growth rate and food processing efficiency. To summarize, this research revealed that both the availability of plant nutrient and species of host plant can strongly influence the physiology and foliar chemistry of host plants. Moreover, the changes of phytochemical in the host plants may play an important role in affecting the performance (growth and food utilization efficiency) of both species of Pieris butterflies.     

MALDI-TOF mass spectrometry as a tool for differentiation of Bradyrhizobium species: Application to the identification of Lupinus nodulating strains

Genus Bradyrhizobium includes slow growing bacteria able to nodulate different legumes as well as species isolated from plant tumours. The slow growth presented by the members of this genus and the phylogenetic closeness of most of its species difficults their identification. In the present work we applied for the first time Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) to the analysis of Bradyrhizobium species after the extension of MALDI Biotyper 2.0 database with the currently valid species of this genus. With this methodology it was possible to identify strains belonging to phylogenetically closely related species of genus Bradyrhizobium allowing the discrimination among species with rrs gene identities higher than 99%. The application of MALDI-TOF MS to strains isolated from nodules of different Lupinus species in diverse geographical locations allowed their correct identification when comparing with the results of rrs gene and ITS analyses. The nodulation of Lupinus gredensis, an endemic species of the west of Spain, by B. canariense supports the European origin of this species.     

Effect of exposure to evening light on sleep initiation in the elderly: A longitudinal analysis for repeated measurements in home settings

Epidemiologic data have demonstrated associations of sleep-onset insomnia with a variety of diseases, including depression, dementia, diabetes and cardiovascular diseases. Sleep initiation is controlled by the suprachiasmatic nucleus of the hypothalamus and endogenous melatonin, both of which are influenced by environmental light. Exposure to evening light is hypothesized to cause circadian phase delay and melatonin suppression before bedtime, resulting in circadian misalignment and sleep-onset insomnia; however, whether exposure to evening light disturbs sleep initiation in home settings remains unclear. In this longitudinal analysis of 192 elderly individuals (mean age: 69.9 years), we measured evening light exposure and sleep-onset latency for 4 days using a wrist actigraph incorporating a light meter and an accelerometer. Mixed-effect linear regression analysis for repeated measurements was used to evaluate the effect of evening light exposure on subsequent sleep-onset latency. The median intensity of evening light exposure and the median sleep-onset latency were 27.3?lux (interquartile range, 17.9–43.4) and 17?min (interquartile range, 7–33), respectively. Univariate models showed significant associations between sleep-onset latency and age, gender, daytime physical activity, in-bed time, day length and average intensity of evening and nighttime light exposures. In a multivariate model, log-transformed average intensity of evening light exposure was significantly associated with log-transformed sleep-onset latency independent of the former potential confounding factors (regression coefficient, 0.133; 95% CI, 0.020–0.247; p?=?0.021). Day length and nighttime light exposure were also significantly associated with log-transformed sleep-onset latency (p?=?0.001 and p?<?0.001, respectively). In conclusion, exposure to evening light in home setting prolongs subsequent sleep-onset latency in the elderly.     

Effects of salinity on larval stages of the rhizocephalan barnacle Loxothylacus texanus: survival and metamorphosis in response to the host, Callinectes sapidus

It is known that the rhizocephalan barnacle Loxothylacus texanus infects the greater blue crab, Callinectes sapidus, in the Gulf of Mexico and adjacent waters, however, factors that affect the prevalence and distribution of this parasite, particularly the dispersive larval stages of this organism, are not well understood. In the current study, the effects of salinity on larval survival and the metamorphosis of L. texanus in response to postmolt host exoskeleton were examined. Acute and acclimated responses were similar. Larval survival was highest in the 20-35‰ range, with 100% mortality of nauplii at all salinities <20‰ and >50‰. L. texanus cyprids were able to metamorphose over a broad range of salinities (15-60‰). In several cases, metamorphosis was actually greatest at high salinities (40-50‰). These data predict that L. texanus larvae would be concentrated in portions of Gulf of Mexico waters with salinities >20‰ such as the mouths of estuaries and bays. Conversely, upper regions of estuaries may be inhospitable to the dispersive (naupliar) stage of the parasite and may serve as a refuge from infection for host crabs.     

Analysis of molecular markers for metamorphic competency and their response to starvation or feeding in the mosquito, Aedes aegypti (Diptera: Culicidae)

The nutritional condition of fourth instar larvae of the yellow fever mosquito, Aedes aegypti, governs female longevity and egg production, both are key determinants of pathogen transmission. As well, nutrition provisions larval growth and development and attains its greatest pace in the last larval instar in preparation for metamorphosis to an adult. These developmental processes are regulated by a complex endocrine interplay of juvenile hormone, neuropeptides, and ecdysteroids that is nutrition sensitive. We previously determined that feeding for only 24 h post-ecdysis was sufficient for fourth instar Ae. aegypti larvae to reach critical weight and accumulate sufficient nutritional stores to commit to metamorphosis. To understand the genetic basis of metamorphic commitment in Ae. aegypti, we profiled the expression of 16 genes known to be involved in the endocrine and nutritional regulation of insect metamorphosis in two ways. The first set is a developmental profile from the beginning of the fourth instar to early pupae, and the second set is for fourth instars starved or fed for up to 36 h. By comparing the two sets, we found that seven of the genes (AaegCYP302, AaegJHE43357, AaegBrCZ4, AaegCPF1-2, AaegCPR-7, AaegPpl, and AaegSlif) were expressed during metamorphic commitment in fourth instars and in fed but not starved larvae. Based on these results, the seven genes alone or in combination may serve as molecular indicators of nutritional and metamorphic status of fourth instar Ae. aegypti larvae and possibly other mosquito species in field and laboratory studies to gauge sub-lethal effects of novel and traditional cultural or chemical controls.     

Simple methods for the estimation and sensitivity analysis of principal strata effects using marginal structural models: Application to a bone fracture prevention trial

In randomized clinical trials, it is often of interest to estimate the effect of treatment on quality of life (QOL), in addition to those on the event itself. When an event occurs in some patients prior to QOL score assessment, investigators may compare QOL scores between patient subgroups defined by the event after randomization. However, owing to postrandomization selection bias, this analysis can mislead investigators about treatment efficacy and result in paradoxical findings. The recent Japanese Osteoporosis Intervention Trial (JOINT‐02), which compared the benefits of a combination therapy for fracture prevention with those of a monotherapy, exemplifies the case in point; the average QOL score was higher in the combination therapy arm for the unfractured subgroup but was lower for the fractured subgroup. To address this issue, principal strata effects (PSEs), which are treatment effects estimated within subgroups of individuals stratified by potential intermediate variable, have been discussed in the literature. In this paper, we describe a simple procedure for estimating the PSEs using marginal structural models. This procedure utilizes SAS code for the estimation. In addition, we present a simple sensitivity analysis method for examining the resulting estimates. The analyses of JOINT‐02 data using these methods revealed that QOL scores were higher in the combination therapy arm than in the monotherapy arm for both subgroups.     

The microenvironment of the ovarian follicle in the postpartum dairy cow: Effects on reagent transfer from cumulus cells to oocytes in vitro

This study's hypothesis was that the nutrient composition in follicular fluid (FF) of ovarian follicles in early lactating postpartum cows may influence reagent transfer from cumulus cells (CC) to the oocyte. To test this, concentrations of amino acids (AA), cholesterol, glucose, and nonesterified fatty acids were measured in FF from the largest antral follicles at Days 21 and 46 postpartum during which time, most animals were expected to have resumed ovulatory activity. From the range of concentrations measured, two media compositions (Lac and Half-Lac) were prepared to compare with medium 199 (M199). The AA and cholesterol concentrations in FF were on average, approximately 35% and greater than 1000% higher than in M199, respectively. The nonesterified fatty acids, but not glucose, concentrations also exceeded those in M199. The transfer of fluorescent dye from CC to oocytes in bovine cumulus-oocyte complexes incubated with and without phosphodiesterase inhibitors (dipyridamole and milrinone) and/or forskolin was assessed. Maximum dye accumulation in oocytes incubated in M199 occurred after 4 hours and was further increased (P < 0.001) by dipyridamole. The addition of dipyridamole to Lac, but not Half-Lac, media also increased dye accumulation. There were effects of media (P < 0.001), cholesterol (P < 0.001), and forskolin (P < 0.05) on dye accumulation but no effects of stearic or palmitic acid in either Lac or Half-Lac media. The addition of oleic acid in Half-Lac (P < 0.01), but not Lac, media inhibited dye accumulation. These results support the hypothesis that reagent transfer from CC to oocytes is compromised when the AA composition in FF is low, as sometimes occurs during early lactation.     

Effects of a transition from normoxia to anoxia on yeast cytochrome c oxidase and the mitochondrial respiratory chain: Implications for hypoxic gene induction

Previous studies have demonstrated that the mitochondrial respiratory chain and cytochrome c oxidase participate in oxygen sensing and the induction of some hypoxic nuclear genes in eukaryotes. In addition, it has been proposed that mitochondrially-generated reactive oxygen and nitrogen species function as signals in a signaling pathway for the induction of hypoxic genes. To gain insight concerning this pathway, we have looked at changes in the functionality of the yeast respiratory chain as cells experience a shift from normoxia to anoxia. These studies have revealed that yeast cells retain the ability to respire at normoxic levels for up to 4 h after a shift and that the mitochondrial cytochrome levels drop rapidly to 30-50% of their normoxic levels and the turnover rate of cytochrome c oxidase (COX) increases during this shift. The increase in COX turnover rate cannot be explained by replacing the aerobic isoform, Va, of cytochrome c oxidase subunit V with the more active hypoxic isoform, Vb. We have also found that mitochondria retain the ability to respire, albeit at reduced levels, in anoxic cells, indicating that yeast cells maintain a functional mitochondrial respiratory chain in the absence of oxygen. This raises the intriguing possibility that the mitochondrial respiratory chain has a previously unexplored role in anoxic cells and may function with an alternative electron acceptor when oxygen is unavailable.     

Severe renal tubulopathy in a newborn due to BCS1L gene mutation: Effects of different treatment modalities on the clinical course

Very early onset Toni–Debré–Fanconi Syndrome, a disorder of proximal renal tubules of the kidney which results in the increased urinary excretion of glucose, amino acids, uric acid, phosphate and bicarbonate, could be the manifestation of various inborn errors. Defects of oxidative phosphorylation are a heterogeneous group of disorders with various clinical presentations. Recently, patients with early liver failure, renal tubulopathy and encephalopathy due to the mutations in the BCS1L gene coding for a structural protein in mitochondrial complex III have been described.     

Effects of elevated CO2 on leaf gas exchange in beech and oak at two levels of nutrient supply: consequences for sensitivity to drought in beech

Beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) were grown from seed for two whole seasons at two CO₂ concentrations (ambient and ambient + 250 μmol mol^?1) with two levels of soil nutrient supply. Measurements of net leaf photosynthetic rate (A) and stomatal conductance (g_s) of well-watered plants were taken over both seasons; a drought treatment was applied in the middle of the second growing season to a separate sample of beech drawn from the same population. The net leaf photosynthetic rate of well-watered plants was stimulated in elevated CO₂ by an average of 75% in beech and 33% in oak; the effect continued through both growing seasons at both nutrient levels. There were no interactive effects of CO₂ concentration and nutrient level on A or g_s in beech or oak. Stomatal conductance was reduced in elevated CO₂ by an average of 34% in oak, but in beech there were no significant reductions in g_s except under cloudy conditions (–22% in elevated CO₂). During drought, there was no effect of CO₂ concentration on g_s in beech grown with high nutrients, but for beech grown with low nutrients, g_s was significantly higher in elevated CO₂, causing more rapid soil drying. With high nutrient supply, soil drying was more rapid at elevated CO₂ due to increased leaf area. It appears that beech may substantially increase whole-plant water consumption in elevated CO₂, especially under conditions of high temperature and irradiance when damage due to high evaporative demand is most likely to occur, thereby putting itself at risk during periods of drought.     

Effects of constant and varying temperatures on the development of blue swimmer crab (Portunus pelagicus) larvae: Laboratory observations and field predictions for temperate coastal waters

Temperature is widely held to be a critical factor for the development of marine invertebrate larvae. We investigated three specific aspects of this relationship for the blue swimmer crab, Portunus pelagicus, in a temperate gulf: (1) the effects of different but temporally constant temperatures on the survival and developmental period of larvae reared in the laboratory, (2) the effects of varying temperatures on the survival and developmental period of larvae reared in the laboratory, and (3) prediction of larval developmental periods under seasonal temperature changes found in the field. Temperature had a marked effect on larval survival. At constant temperatures of 22.5 and 25 °C larval survival was far greater than at lower temperatures down to 17 °C, and developmental period of the larval period was inversely related to (constant) temperature. However, larvae in temperate coastal waters will usually be exposed to seasonally varying, rather than constant, temperatures. To account for this, a larval developmental period model was created and then verified in the laboratory by rearing larvae under varying temperatures. Results of this work demonstrated that developmental periods were markedly different under constant versus varying temperature regimes. Using different temperature simulations for a temperate gulf (Gulf St Vincent, South Australia), the developmental period model predicted that in years of ‘average’ seasonal temperature changes, total larval developmental period could range from 26 to 45 days depending on the day of hatching. In such cases, peak postlarval settlement was predicted to occur between mid January and mid March. Results from this study also predict that larval survival (and thus postlarval settlement) will be maximised in years with abnormally warm summers. Whilst the developmental period model was used to make predictions of developmental period for P. pelagicus in a temperate gulf, it could readily be adapted to predict developmental periods in other coastal environments.     

A gas chromatography-mass spectrometry method for the quantitation of N-nitrosoproline and N-acetyl-S-allylcysteine in human urine: Application to a study of the effects of garlic consumption on nitrosation

Biomarkers in urine can provide useful information about the bioactivation of chemical carcinogens and can be used to investigate the chemoprotective properties of dietary nutrients. N-Nitrosoproline (NPRO) excretion has been used as an index for endogenous nitrosation. In vitro and animal studies have reported that compounds in garlic may suppress nitrosation and inhibit carcinogenesis. We present a new method for extraction and sensitive detection of both NPRO and N-acetyl-S-allylcysteine from urine. The latter is a metabolite of S-allylcysteine, which is found in garlic. Urine was acidified and the organic acids were extracted by reversed-phase extraction (RP-SPE) and use of a polymeric weak anion exchange (WAX-SPE) resin. NPRO was quantified by isotope dilution gas chromatography-mass spectrometry (GC-MS) using [¹³C₅]NPRO and N-nitrosopipecolinic acid (NPIC) as internal standards. This method was used to analyze urine samples from a study that was designed to test whether garlic supplementation inhibits NPRO synthesis. Using this method, 2.4 to 46.0 ng NPRO/ml urine was detected. The method is straightforward and reliable, and it can be performed with readily available GC-MS instruments. N-Acetyl-S-allylcysteine was quantified in the same fraction and detectable at levels of 4.1 to 176.4 ng/ml urine. The results suggest that 3 to 5 g of garlic supplements inhibited NPRO synthesis to an extent similar to a 0.5-g dose of ascorbic acid or a commercial supplement of aged garlic extract. Urinary NPRO concentration was inversely associated with the N-acetyl-S-allylcysteine concentration. It is possible that allyl sulfur compounds found in garlic may inhibit nitrosation in humans.