Environmental sensitivity and heterosis for egg laying in Drosophila melanogaster

Summary Genotype × temperature interactions for egg laying were studied in Drosophila melanogaster using two sets of half diallel crosses: one between inbred lines of the same geographic origin, and the other between established laboratory, newly derived inbred lines from different geographic origins. The sensitivity of most genotypes to changes in temperature was adequately described as a linear regression of mean in temperature. The regression coefficients (linear sensitivities) were heterogeneous between genotypes. Hybrids were more affected by temperature variation than were inbreds. All the heterogeneity of linear sensitivities was accounted for by a linear function of the genotypic means, which strongly suggests that a scale effect is responsible for the differences in sensitivity to temperature. In contrast, no general relationship was found between standard error deviation (sensitivity to small environmental changes) and mean performance between genotypes, although hybrids tended to be less variable than inbreds. This shows that the sensitivity to environmental variation depends not only on the genotype, but also on the nature of the environmental variation. The variability within temperatures may be affected by the general homeostasis of individual genotypes, while the variability between temperatures could be the result of genes directly affecting the trait and their multiplicative interaction with the environment.     

Activity of ajoene on dermatophytes, Candida albicans and Malassezia furfur.

The sensitivity in vitro of an isolate of Trichophyton rubrum and another of Trichophyton mentagrophytes to ajoene. This compound inhibited the growth of both isolates, showing an minimal inhibitory concentration (MIC) of 60 microg/ml and a minimal fungicidal concentration (MFC) of 75 microg/ml. In vivo, the ajoene cream at 0.4% used once a day and every five days in 38 patients (thirty dermatophytosis and eight Candida intertrigo cases) achieved a low percentage of cures (23.3% and 12.5%, respectively). However, an excellent clinic response was obtained in eight patients with pityriasis versicolor, with a cure in 87.5% of the cases.     

Rates of movement of transposable elements inDrosophila melanogaster

Mobilization rates of nine families of transposable elements (P, hobo, FB, gypsy, 412, copia, blood, 297, andjockey) were estimated by using 182 lines. Lines were started from a completely isogenic population ofDrosophila melanogaster, carrying the markersepia as an indicator of possible contamination, and have been accumulating spontaneous mutations independently for 80 generations of brother-sister (or two double-first-cousin) matings. Transposable element movements have been analyzed in complete genomes by the Southern technique. Mobilization was a rare event, with an average rate of 10^?5 per site per generation. The most active element wasFB. In contrast, the retroelementsgypsy andblood did not move at all. Most changes in restriction patterns were consistent with rearrangements rather than with true transposition. The euchromatic or heterochromatic location of elements was tested by comparing insertion patterns from adults and salivary glands. Certain putative rearrangements involved heterochromatic copies of the retroelements412, copia or297. Clustering of movement across families was observed, suggesting that movement of different families may be non-independent. An association between modified insertion patterns and mutant effects on quantitative traits shows that spontaneous transposition events cause continuous variation.     

The Distribution of Spontaneous Mutations on Quantitative Traits and Fitness in Drosophila Melanogaster

Starting from a completely homozygous population of Drosophila melanogaster, two groups of 100 inbred lines each were established and maintained for 46 generations, by a single brother-sister mating and two double first cousin matings, respectively. Sternopleural bristle number, wing length and wing width were simultaneously scored in all lines every 4-5 generations. The means of four lines in each group departed significantly from the overall mean and, in each case, this was attributed to a single mutation of relatively large effect on at least one trait (0.3-1.4 environmental standard deviations in absolute value). Further analyses revealed widespread pleiotropy, similar gene action of a given mutation for all traits affected, and predominant additive action. No apparent association was found between the magnitudes of mutational effects on the traits and fitness. However, all recessive mutations were deleterious. The distribution of mutant effects was asymmetrical (positive for bristles and negative for wing measurements). Moreover, these distributions had a high variance and may be leptokurtic, due to the presence of major genes. Estimates of the ratio of new mutational variance to environmental variance ranged within (0.7-3.4) x 10(-3), those for wing measurements being generally larger. In agreement with theory, the rate of between-line differentiation was independent of population size.     

Glutamate receptors of the A5 region modulate cardiovascular responses evoked from the dorsomedial hypothalamic nucleus and perifornical area

To assess the possible function of glutamate in the interaction between the dorsomedial hypothalamic nucleus-perifornical area (DMH-PeF) and the A5 pontine region (A5), cardiovascular and respiratory changes were studied in response to electrical stimulation of the DMH-PeF (1 ms pulses, 30–50 μA given at 100 Hz for 5 s) before and after the microinjection of kynurenic acid (non-specific glutamate receptor antagonist; 50 nl, 5 nmol), MK-801 (NMDA receptor antagonist; 50 nl, 50 nmol), CNQX (non-NMDA receptor antagonist; 50 nl, 50 nmol) or MCPG (metabotropic glutamate receptor antagonist; 50 nl, 5 nmol) within the A5 region. DMH-PeF electrical stimulation elicited a pressor (p <?0.001) and tachycardic response (p <?0.001) which was accompanied by an inspiratory facilitation characterised by an increase in respiratory rate (p <?0.001) due to a decrease in expiratory time (p <?0.01). Kynurenic acid within the A5 region decreased the tachycardia (p <?0.001) and the intensity of the blood pressure response (p <?0.001) to DMH-PeF stimulation. After the microinjection of MK-801 and CNQX into the A5 region, the magnitude of the tachycardia and the pressor response were decreased (p <?0.05 and p <?0.01; p <?0.001 and p <?0.05, respectively). After MCPG microinjection into the A5 region, a decrease in the tachycardia (p <?0.001) with no changes in the pressor response was observed during DMH-PeF stimulation. The respiratory response elicited by DMH-PeF stimulation was not changed after the microinjection of kynurenic acid, MK-801, CNQX or MCPG within the A5 region. These results suggest that A5 region glutamate receptors play a role in the cardiovascular response elicited from the DMH-PeF. The possible mechanisms involved in these interactions are discussed.     

A new species of Hemibrycon (Characiformes,Characidae, Stevardiinae) from the upper Magdalena River basin in Colombia

Hemibrycon iqueima sp. nov., is described from small streams in the Magdalena drainage at the foothills of the western slope of the Eastern Cordillera of the Colombian Andes, Suarez municipality, Tolima Department, Colombia. The new species is distinguished from its congeners in the Magdalena–Cauca River basin by a combination of characters related to snout–anal‐fin origin length, head length, dorsal–pectoral fin distance, dorsal‐fin–hypural distance, postorbital distance, orbital diameter, snout length, number of total vertebrae, pre‐dorsal scales, scale rows between anal‐fin origin and lateral line, number of branched rays of the anal fin, maxillary teeth number and number and arrangement of hooks on the branched rays of the pectoral and dorsal fins. In addition, the validity of this species is supported by previous molecular analyses that included specimens of the new species that had been erroneously identified. Phylogenetic relationships between the new species and congeners from Pacific coast basins are discussed.     

Changes in ectomycorrhizal fungal community composition and declining diversity along a 2‐million‐year soil chronosequence

Ectomycorrhizal (ECM) fungal communities covary with host plant communities along soil fertility gradients, yet it is unclear whether this reflects changes in host composition, fungal edaphic specialization or priority effects during fungal community establishment. We grew two co‐occurring ECM plant species (to control for host identity) in soils collected along a 2‐million‐year chronosequence representing a strong soil fertility gradient and used soil manipulations to disentangle the effects of edaphic properties from those due to fungal inoculum. Ectomycorrhizal fungal community composition changed and richness declined with increasing soil age; these changes were linked to pedogenesis‐driven shifts in edaphic properties, particularly pH and resin‐exchangeable and organic phosphorus. However, when differences in inoculum potential or soil abiotic properties among soil ages were removed while host identity was held constant, differences in ECM fungal communities and richness among chronosequence stages disappeared. Our results show that ECM fungal communities strongly vary during long‐term ecosystem development, even within the same hosts. However, these changes could not be attributed to short‐term fungal edaphic specialization or differences in fungal inoculum (i.e. density and composition) alone. Rather, they must reflect longer‐term ecosystem‐level feedback between soil, vegetation and ECM fungi during pedogenesis.     

Are respiratory complications of <Emphasis Type="Italic">Plasmodium vivax</Emphasis> malaria an underestimated problem?

Background

Respiratory complications are uncommon, but often life-threatening features of Plasmodium vivax malaria. This study aimed to estimate the prevalence and lethality associated with such complications among P. vivax malaria patients in a tertiary hospital in the Western Brazilian Amazon, and to identify variables associated with severe respiratory complications, intensive care need and death. Medical records from 2009 to 2016 were reviewed aiming to identify all patients diagnosed with P. vivax malaria and respiratory complications. Prevalence, lethality and risk factors associated with WHO defined respiratory complications, intensive care need and death were assessed.

Results

A total of 587 vivax malaria patients were hospitalized during the study period. Thirty (5.1%) developed respiratory complications. Thirteen (43.3%) developed severe respiratory complications, intensive care was required for 12 (40%) patients and 5 (16.6%) died. On admission, anaemia and thrombocytopaenia were common findings, whereas fever was unusual. Patients presented different classes of parasitaemia and six were aparasitaemic on admission. Time to respiratory complications occurred after anti-malarials administration in 18 (60%) patients and progressed very rapidly. Seventeen patients (56.7%) had comorbidities and/or concomitant conditions, which were significantly associated to higher odds of developing severe respiratory complications, need for intensive care and death (p < 0.05).

Conclusion

Respiratory complications were shown to be associated with significant mortality in this population. Patients with comorbidities and/or concomitant conditions require special attention to avoid this potential life-threatening complication.