Hyperdominance in fruit production in the Brazilian Atlantic rain forest: the functional role of plants in sustaining frugivores

The availability of fruits is critical for tropical forests, where the majority of plant species rely upon animal vectors for seed dispersal. However, we do not know how fruit production is temporally distributed over species and families. Two plant families are particularly important in floristic inventories of Atlantic rain forests: Arecaceae, a few species of which are highly abundant; and Myrtaceae, which is abundant and displays outstanding species diversity. In this context, we asked whether hyperdominance occurs in fruit production in the Atlantic rain forest, and whether it occurs in the abundant species of Arecaceae and Myrtaceae. We investigated whether the temporal fruit production patterns differ between Myrtaceae, Arecaceae, and the plant community as a whole. We also applied a functional dispersion index to assess the temporal fruit diversity over a 2‐yr period, with regard to morphological and phenological traits. We found that the phenomenon of hyperdominance occurs in fruit production: five species accounted for more than half of the pulp biomass. Arecaceae fruit biomass peaked at the end of wet season, overlapping with the community peak; whereas Myrtaceae species fruited throughout the year and were an important resource during periods of food scarcity. Myrtaceae filled more of the fruit morphospace over time because their fruits exhibit a large range of morphologies and phenological strategies. Our results demonstrated the importance of combining phenology and fruit morphology in the evaluation of resource availability, which revealed periods of high fruit diversity that could support a range of frugivore sizes and maintain overall ecosystem functionality.     

The original Michaelis constant: translation of the 1913 Michaelis-Menten paper

Nearly 100 years ago Michaelis and Menten published their now classic paper [Michaelis, L., and Menten, M. L. (1913) Die Kinetik der Invertinwirkung. Biochem. Z. 49, 333-369] in which they showed that the rate of an enzyme-catalyzed reaction is proportional to the concentration of the enzyme-substrate complex predicted by the Michaelis-Menten equation. Because the original text was written in German yet is often quoted by English-speaking authors, we undertook a complete translation of the 1913 publication, which we provide as Supporting Information . Here we introduce the translation, describe the historical context of the work, and show a new analysis of the original data. In doing so, we uncovered several surprises that reveal an interesting glimpse into the early history of enzymology. In particular, our reanalysis of Michaelis and Menten's data using modern computational methods revealed an unanticipated rigor and precision in the original publication and uncovered a sophisticated, comprehensive analysis that has been overlooked in the century since their work was published. Michaelis and Menten not only analyzed initial velocity measurements but also fit their full time course data to the integrated form of the rate equations, including product inhibition, and derived a single global constant to represent all of their data. That constant was not the Michaelis constant, but rather V(max)/K(m), the specificity constant times the enzyme concentration (k(cat)/K(m) × E(0)).     

Morphological changes in lung tissue of victims associated with the 2009 A H1N1/v09 influenza pandemic in Colombia

Introduction. Influenza is an acute respiratory infection that may be seasonal or pandemic. In 2009 The World Health Organization (WHO) declared an influenza pandemia; 3,876 cases and 239 deaths were reported in Colombia. Objective. The morphological changes in lung tissues associated with virus infection H1N1/v09 were described from autopsied victims. Materials and methods. Seventy-five cases were diagnosed by RT-PCR for influenza A H1N1/v09, of which the lungs of 20 were selected for morphological study by light microscopy, optical microscopy, high-resolution transmission electron microscopy and immunohistochemistry. Results. Of the 75 cases, 83% had viral pneumonitis and 17% alveolitis. Complications included intra-alveolar hemorrhage (66%), edema (89%), diffuse alveolar damage (2%), and bacterial co-infection (32%). Morphological changes were as follows: destruction of the alveolar epithelium and interstitium, edema, macrophages with vacuolated cytoplasm,and infiltration of polymorphonuclear leukocytes in the alveolar lumen and interstitium, vacuolization cytoplasmic type I pneumocytes and electronedense bodies in cellular debris in the alveolar lumen, and immunoreactivity of viral antigens in bronchiolar epithelial cells and alveolar infiltrate. Conclusion. The low percentage of bacterial co-infection observed in these cases was a prominent feature, and suggested that the fatal result was probably not associated with secondary bacterial disease (Indicated by previous reports). The tissue lesions were attributed to tissue damage due to viral lesion, as well as the cellular and humoral inflammatory response associated with infiltration by polymorphonucleocytes and macrophages in the interstitium and alveolar lumen.     

Plant aging and excess light enhance flavan-3-ol content in Cistus clusii

Physiological studies on aging in perennials are mainly focused either on the primary metabolism or the hormonal regulation of the process. However, to our knowledge, the involvement of the secondary metabolism in this process has not yet been explored. Cistus clusii, a Mediterranean sclerophyllous evergreen bush, shows considerable amounts of flavan-3-ols in leaves. In the present study, we aimed at determining the impact of environmental conditions and plant aging in the flavan-3-ol content in C. clusii plants grown in field conditions, which included summer drought and recovery periods. Six-year-old plants suffered more from photo-oxidative stress, especially during excess light periods, and showed lower maximum photosynthetic rates than 1-year-old plants. C. clusii leaves accumulated (−)-epigallocatechin gallate in early summer, in a strong positive correlation with both the photon flux density and the photoperiod, but not with the plant water status. Moreover, C. clusii plants accumulated proanthocyanidins (polymeric flavan-3-ols) in leaves during summer. Older plants showed higher levels of proanthocyanidins and (−)-epicatechin, but only during late spring and summer. From the result of the present study, we conclude that excess light enhances flavan-3-ol content in C. clusii, a process enhanced as plants age due to increased excess light stress.     

Characterization of the reproductive effects of the anorexigenic VGF-derived peptide TLQP-21: in vivo and in vitro studies in male rats

VGF (nonacronymic) is a 68-kDa protein encoded by the homonymous gene, which is expressed abundantly at the hypothalamus and has been involved in the control of metabolism and body weight homeostasis. Different active peptide fragments are generated from VGF, including TLQP-21. Circumstantial evidence has suggested that VGF might also participate in the control of reproduction. Yet its mechanisms of action and the eventual role of specific VGF-derived peptides on the hypothalamic-pituitary-gonadal (HPG) axis remain unknown. Herein we report a series of studies on the reproductive effects of TLQP-21 as evaluated in male rats by a combination of in vivo and in vitro analyses. Central administration of TLQP-21 induced acute gonadotropin responses in pubertal and adult male rats, likely via stimulation of GnRH secretion, as documented by static incubations of hypothalamic tissue. In addition, in pubertal (but not adult) males, TLQP-21 stimulated LH secretion directly at the pituitary level. Repeated central administration of TLQP-21 to pubertal males subjected to chronic undernutrition was able to ameliorate the hypogonadotropic state induced by food deprivation. In contrast, chronic administration of TLQP-21 to fed males at puberty resulted in partial desensitization and puberty delay. Finally, in adult (but not pubertal) males, TLQP-21 enhanced hCG-stimulated testosterone secretion by testicular tissue in vitro. In summary, our data are the first to document a complex and multifaceted mode of action of TLQP-21 at different levels of the male HPG axis with predominant stimulatory effects, thus providing a tenable basis for the (direct) reproductive role of this VGF-derived peptide.     

Steroid Hormones and Facial Traits in The Recognition of A Potential Rival in Men

There is evidence that the cognitive skills that enable an individual to evaluate their own physical characteristics and those of others are an important strategy for recognizing a potential rival in intrasexual competition in humans. It has been shown that these strategies are facilitated by steroid hormones such as testosterone (T) and cortisol (C). This study examines whether men recognize as attractive some facial characteristics of other men that the literature reports as attractive to women when observing the faces of other men, under the hypothesis that the presence of these features indicates a potential rival. The characteristics evaluated were facial fluctuating asymmetry (FA), dominance (D), and assertiveness (A). In addition, we investigated whether the recognition of these facial characteristics depended upon the characteristics of the evaluator, that is, of the man's own FA, D, and A, or on the concentration of T and C in saliva. We found that evaluators with greater FA (asymmetric faces) and lower concentrations of C rated the faces of more symmetrical men as more attractive to women and as the most likely to represent potential rivals. Men with asymmetric faces exhibited higher levels of T than low FA males, although the difference was not significant. Conversely, men with low levels of FA (symmetric) identified the faces of more assertive men as the most attractive to women and the most likely to represent potential rivals. We concluded that men with high FA levels are more prone to recognize a potential rival in others according to female preferences, and this identification enables them to reduce the cost of competition.     

Biogeography and conservation of aquatic fauna in spring-fed tropical canyons of the southern Sonoran Desert,Mexico

In arid regions, spring-fed habitats are frequently the only year-round source of surface water and are essential habitats for aquatic organisms and primary water sources for terrestrial animals and human settlements. While these habitats have been relatively well-studied in some regions, those of the southern Sonoran Desert have received little attention. In 2008 and 2009, we documented the biodiversity of aquatic animals at 19 sites across three arid mountain ranges in Sonora, Mexico, characterized macrohabitat types, examined seasonal variation in aquatic invertebrate communities, and explored the effects of an exotic fish (tilapia) on native communities. We documented >220 aquatic animal species, including several new species and range extensions for others. Macrohabitat type (oasis, tinaja, riffle, and seep) was more important than geographic location in structuring aquatic invertebrate communities at the scale of our study area (~9,000 km²). We found little evidence of predictable seasonal variation in invertebrate communities, despite dramatic hurricane-induced flooding. Aquatic vertebrates were not diverse across the study region (4 amphibian species and 2 species each of fishes and reptiles), but were often locally abundant. Presence of non-native tilapia at one site was associated with reduced abundances of native leopard frogs and reduced richness and density of native aquatic invertebrates. The most pressing aquatic habitat conservation concerns in the region, as in other deserts, are groundwater withdrawal, unmanaged recreational visitation, and the introduction of exotic species. Spring-fed habitats around the world have been called hotspots of freshwater biodiversity, and those of the Sonoran Desert are no exception.     

A new species of Lichtheimia (Mucoromycotina,Mucorales) isolated from Brazilian soil

During studies on Mucorales in semiarid and littoral dune areas in the northeast of Brazil, two cultures of an Absidia-like species were isolated from soil. They were characterized based on morphological, physiological and molecular data (5.8S and LSU rDNA sequences). The phylogenetic analyses of the isolates revealed that they belong to the Lichtheimiaceae and are closely related to species of Lichtheimia. The two isolates produced simple or branched, erect and circinate sporophores, occasionally with a septum under the sporangia, characteristics also common in Lichtheimia species. However, different from the described Lichtheimia species, the columellae of our isolates were mainly short hemispherical, never spatulate or elliptical and without projections. Sometimes, a long conical or bell shaped apophysis was found. Both isolates grew better at 30–35 °C, with no development at 42 °C, and giant cells were not observed. Based on the evidence of the analyzed datasets a new species of Lichtheimia is proposed.