Sex pheromone and period gene characterization of Lutzomyia longipalpis sensu lato (Lutz & Neiva) (Diptera: Psychodidae) from Posadas, Argentina

Lutzomyia longipalpis s.l. is the primary vector of Leishmania (L.) infantum in the New World. In this study, male Lutzomyia longipalpis specimens from Posadas, Argentina were characterized for two polymorphic markers: the male sex pheromone and the period (per) gene. The male sex pheromone was identified as (S)-9-methylgermacrene-B, the same compound produced by Lu. longipalpis from Paraguay and many populations from Brazil. The analysis of per gene sequences revealed that the population from Argentina is significantly differentiated from previously studied Brazilian populations. Marker studies could contribute to the understanding of the distribution and spread of urban American visceral leishmaniasis, thus aiding in the design of regional surveillance and control strategies.     

Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

Bacillus subtilis sporulation is a last-resort phenotypical adaptation in response to starvation. The regulatory network underlying this developmental pathway has been studied extensively. However, how sporulation initiation is concerted in relation to the environmental nutrient availability is poorly understood. In a fed-batch fermentation set-up, in which sporulation of ultraviolet (UV)-mutagenized B. subtilis is repeatedly triggered by periods of starvation, fitter strains with mutated tagE evolved. These mutants display altered timing of phenotypical differentiation. The substrate for the wall teichoic acid (WTA)-modifying enzyme TagE, UDP-glucose, has recently been shown to be an intracellular proxy for nutrient availability, and influences the timing of cell division. Here we suggest that UDP-glucose also influences timing of cellular differentiation.     

Morphological evidence of hybridization between Ramphocelus flammigerus subspecies (Passeriformes: Thraupidae) in Colombia

Habitat modifications such as deforestation and the increase of agricultural activities, have led to uncommon faunal interactions. In Colombia, this condition have caused the secondary contact of subspecies of Ramphocelus flammigerus populations from Cauca valley and the Pacific coast; and some specimens with rumps of intermediate colors of the subspecies have been found and are thought as hybrids. The objective of this study was to assess the presence of morphological evidence that may suggest hybridization and may explain the origin of individuals with intermediate coloration. We predict that if subspecies hybridize, they will be more similar in morphology when coexisting than when separated. Alternatively, coexisting subspecies might diverge in sympatry, because of selection to reduce competition for resources (character displacement). For this, a survey in 15 localities was undertaken: 10 allopatric areas (five for each subspecies), and five sympatric areas. Mist nets were used to capture individuals and a total of seven morphological characters were measured. To identify the patterns of morphological variation, we compared morphology of subspecies, sympatric and allopatric populations and individuals of intermediate colors. Consequently, we performed discriminant analysis and test for differences between groups by using 95% confidence intervals for log-ratio tests. A total of 112 individuals were captured (46 intermediate-colored individuals, 20 R. f. flammigerus, and 46 R.f. icteronotus. Discriminant analyses showed that subspecies were well differentiated, and intermediate individuals overlapped with them. Log-ratio test, based on Mahalanobis distances, showed that intermediate individuals were morphologically more similar to both subspecies than subspecies themselves. In addition, log-ratio tests showed that subspecies sympatric populations were similar but allopatric ones were different, and that individuals of intermediate colors were more similar to sympatric than to allopatric populations of the two subspecies. Therefore, morphological evidence supports the predictions of a hybridization hypothesis among the subspecies of R. flammigerus. In conclusion, the analysis of morphological variation in R. flammigerus suggests that hybridization between subspecies is occurring and that a process of genetic introgression is probably in progress.     

Nectarivory by the plant-tissue feeding predator Macrolophus pygmaeus Rambur (Heteroptera: Miridae): Nutritional redundancy or nutritional benefit?

Most predators and parasitoids feed on plant-provided food (nectar, pollen) or engage in herbivory during at least part of their life stages. Plant feeding by these insects plays an important role in driving predator-herbivore dynamics. Thus, understanding the effects of plant feeding on omnivores could be an important element in improving biological control strategies. The mirid Macrolophus pygmaeus is an omnivorous heteropteran predator of whitefly and other pests. Unlike other predators that need to seek out accessible nectar to meet their carbohydrate requirements, mirid bugs can access the plant's carbohydrate resources by feeding directly on plant tissues. Leaf and stem feeding could be seen as a nutritional surrogate that allows mirids to become independent of nectar availability. However, to date feeding experiments have not yet considered nectar feeding by these mirid predators. In this study we demonstrate that M. pygmaeus survival is prolonged on broad bean plants featuring extrafloral nectar as compared to broad bean with extrafloral nectaries removed, irrespective of the presence of cattail pollen. Survival on extrafloral nectar was comparable to the survival by individuals kept on broad bean provided with eggs of Ephestia kuehniella as prey. Also, a greater proportion of mirid females laid eggs when extrafloral nectar was available as compared to those confined on nectariless plants without supplemental food.     

Early clinical features of dengue virus infection in nicaraguan children: a longitudinal analysis

Background

Tens of millions of dengue cases and approximately 500,000 life-threatening complications occur annually. New tools are needed to distinguish dengue from other febrile illnesses. In addition, the natural history of pediatric dengue early in illness in a community-based setting has not been well-defined.

Methods

Data from the multi-year, ongoing Pediatric Dengue Cohort Study of approximately 3,800 children aged 2–14 years in Managua, Nicaragua, were used to examine the frequency of clinical signs and symptoms by day of illness and to generate models for the association of signs and symptoms during the early phase of illness and over the entire course of illness with testing dengue-positive. Odds ratios (ORs) and 95% confidence intervals were calculated using generalized estimating equations (GEE) for repeated measures, adjusting for age and gender.

Results

One-fourth of children who tested dengue-positive did not meet the WHO case definition for suspected dengue. The frequency of signs and symptoms varied by day of illness, dengue status, and disease severity. Multivariable GEE models showed increased odds of testing dengue-positive associated with fever, headache, retro-orbital pain, myalgia, arthralgia, rash, petechiae, positive tourniquet test, vomiting, leukopenia, platelets ≤150,000 cells/mL, poor capillary refill, cold extremities and hypotension. Estimated ORs tended to be higher for signs and symptoms over the course of illness compared to the early phase of illness.

Conclusions

Day-by-day analysis of clinical signs and symptoms together with longitudinal statistical analysis showed significant associations with testing dengue-positive and important differences during the early phase of illness compared to the entire course of illness. These findings stress the importance of considering day of illness when developing prediction algorithms for real-time clinical management.     

Kv7 channels can function without constitutive calmodulin tethering

M-channels are voltage-gated potassium channels composed of Kv7.2-7.5 subunits that serve as important regulators of neuronal excitability. Calmodulin binding is required for Kv7 channel function and mutations in Kv7.2 that disrupt calmodulin binding cause Benign Familial Neonatal Convulsions (BFNC), a dominantly inherited human epilepsy. On the basis that Kv7.2 mutants deficient in calmodulin binding are not functional, calmodulin has been defined as an auxiliary subunit of Kv7 channels. However, we have identified a presumably phosphomimetic mutation S511D that permits calmodulin-independent function. Thus, our data reveal that constitutive tethering of calmodulin is not required for Kv7 channel function.     

Maternal separation and early stress cause long‐lasting effects on dopaminergic and endocannabinergic systems and alters dendritic morphology in the nucleus accumbens and frontal cortex in rats

A considerable amount experimental studies have shown that maternal separation (MS) is associated with adult offspring abnormal behavior and cognition disorder. Accordingly, this experimental procedure has been proposed as a predictor for alcohol and drug dependence based on the neurodevelopmental soon after birth. Endocannabinoid system (eCBs) has been implicated in reward processes, including drug abuse and dependence. MS and associated stress causes changes in the eCBs that seem to facilitate alcohol consumption. In this study, we seek to evaluate potential morphological changes in neurons of the frontal cortex (FCx) and nucleus accumbens (NAcc), in the expression of receptors and enzymes of the endocannabinoid and dopamine systems and in second messengers, such as Akt, in adult rats subjected to MS and early stress (MS + ES; 2 × 180 min daily) vs. nonseparated rats (NMS). Results showed that MS + ES induces higher D2R expression and lower D3R, FAAH, and MAGL expression compared with NMS rats. Alterations in total dendritic length were also detected and were characterized by increases in the NAcc while there were decreases in the FCx. We believe MS + ES‐induced changes in the dopaminergic and endocannabinergic systems and in the neuronal microstructure might be contributing to alcohol seeking behavior and, potential vulnerability to other drugs in rats. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 819–831, 2016