Organosulfur compounds alone or in combination with vitamin C protect towards N-nitrosopiperidine- and N-nitrosodibutylamine-induced oxidative DNA damage in HepG2 cells

The aim of this study was to investigate the protective effects of organosulfur compounds (OSCs) alone or in combination with vitamin C towards N-nitrosopiperidine (NPIP) and N-nitrosodibutylamine (NDBA)-induced oxidative DNA damage in the single cell gel electrophoresis (SCGE)/HepG2 assay. Diallyl sulfide (DAS) did not protect against NDBA-induced oxidized purines, but it reduced the oxidized purines induced by NPIP (1 microM, 29%). The formation of formamidopyridine-DNA glycosylase (Fpg) sensitive sites induced by NPIP or NDBA was prevented by dipropyl sulfide (DPS) at concentrations of 1-10 microM (55-24% and 66-15%, respectively). The maximum reduction of the formation of Fpg sensitive sites induced by NPIP was observed at the highest concentration of diallyl disulfide (DADS) (2.5 microM, 38%). However, the oxidative DNA damage induced by NDBA was strongly reduced by DADS at the lowest concentration tested (0.1 microM, 92%). The oxidative DNA damage induced by NPIP or NDBA was prevented by all the concentrations of dipropyl disulfide (DPDS) (0.1-2.5 microM, 59-80% and 51-64%, respectively). DADS and DPDS, in combination with vitamin C showed an overall protective effect towards the formation of Fpg sensitive sites induced by NPIP and NDBA. However, the contribution of OSCs to the protective effect found in combined experiments might not be relevant, because it could be caused by vitamin C alone. One feasible mechanism by which OSCs exert their protective effects towards N-nitrosamine-induced oxidative DNA damage could be by modulation of phase I and II enzyme activities. DADS and DPDS (0.1-2.5 microM) exerted greater inhibition on CYP2E1 and CYP2A6 activity than DAS and DPS (1-50 microM). However, DAS and DADS (1 microM) exerted greater inhibition on CYP1A1 activity than DPS and DPDS (1 microM). DAS/DPS (50 microM) and DADS (2.5 microM) exerted a moderate increase of UDP-glucuronyltransferase (UGT1A4) activity, whereas DPDS (2.5 microM) had the most pronounced effect.     

Corticosterone metabolites in blue tit and pied flycatcher droppings: effects of brood size, ectoparasites and temperature

The hypothalamic-pituitary-adrenal (HPA) axis of birds induces the secretion of corticosterone (CORT) as a response to different ecological variables. In this study we tested experimentally if manipulations of brood size or ectoparasitism led to subsequent differences in the concentration of excreted CORT metabolites of adult and nestling blue tits (Cyanistes caeruleus). No significant effect of the manipulation of brood size was detected in adults or nestlings. No significant effect of ectoparasitism was detected in males or nestlings, although females from uninfested nests showed lower concentrations of excreted CORT metabolites. In addition, we analysed if weather conditions had an influence on the concentration of excreted CORT metabolites of blue tits and pied flycatchers (Ficedula hypoleuca) breeding in the same forest. We detected no effect of weather conditions on adults, but nestlings of both species showed a negative correlation between their excreted CORT metabolites and the average mean temperatures they were subjected to during their growth. This effect was not found in blue tits in a colder year, suggesting that the sensitivity of the HPA axis to ambient temperature may be subjected to interannual variation. Moreover, we found a positive effect of the maximum temperature on the day of sampling on the concentration of CORT metabolites of blue tit nestlings in one of the years. These results suggest that weather conditions may act as environmental stressors to which the HPA axis of blue tit and pied flycatcher nestlings may be sensitive.     

Wild food plants traditionally used in the province of Madrid, Central Spain

This paper reports an ethnobotanical investigation, performed between 1999 and 2002, to determine the wild food plants traditionally used in the province of Madrid (central Spain). One hundred and twenty-three vascular species belonging to 31 families were at one time used as vegetables, wild fruits, in the making of beverages, as seasonings, or as other preparations. Wild vegetables formed the largest group, withScolymus hispanicus, Silene vulgaris, andRumex pulcher the most frequently cooked vegetables, andRorippa nasturtium-aquaticum andMontia fontana the most commonly used in salads. Also common was the consumption of asparagus and several species of climbing plants such asBryonia dioica, Tamus communis, andHumulus lupulus. Ethnobotanical novelties includedSonchus crassifolius, the young sprouts of which were used in salads, and Inula salicina, used to make herbal tea. Some ecological and cultural aspects of the collection of wild plants for food are discussed, as well as the relationships between the food and medicinal uses of some species.     

Species composition and invasion in NW Argentinian secondary forests: Effects of land use history,environment and landscape

Abstract. Successional patches are a large component of forest ecosystems throughout the world and their vegetation composition is conditioned by multiple factors such as land use history, disturbances, environmental conditions and landscape context. We investigated the relative contribution of historical, environmental, biotic and spatial factors in determining vegetation composition and invasion by exotic species in secondary forest patches of Sierra de San Javier, Tucumán, Argentina. We estimated canopy cover for shrub, vine and tree species distributed over 51 patches with known land use history. We also recorded environmental, historical and spatial variables and used multivariate techniques to explore the relationship between forest composition and explanatory variables. Land use, time since abandonment, altitude, slope and cover of different strata were related to the vegetation pattern in the study site, and they were all significantly structured over space. Exotic species appeared to differ from natives in their response to explanatory variables. Overall, exotic species were dominant on the edges of young patches originated from herbaceous crops, but the total number of exotic species was related to the distance to urban areas and small farms identified as potential sources of exotic propagules. Vegetation composition of secondary forests in NW Argentina was related to historical and environmental factors, but spatial variables strongly influenced vegetation composition as well as the variation in explanatory variables.     

Influence of Compatibility System and Life Form on Plant Reproductive Success

Abstract: We studied the compatibility system and the autonomous selfing capacity of 32 native species from the Chaco Serrano forests (central Argentina), and compared fruit set, considering plant life form and compatibility status to evaluate: (i) the extent of the association between life form and compatibility system, (ii) the influence of the life form and/or of the compatibility system on natural fruit set, and (iii) the preemergent reproductive advantages provided by self-compatibility and autonomous self-pollination. Ca. 60 % of the species were self-compatible (SC). Natural fruit set of SC species triplicate those of self-incompatible (SI) species. Almost all SC species have autonomous selfing capacity. Nevertheless, on average, SC species produce more than twice as many fruits through natural pollination in comparison to autonomous selfing, and fruit set obtained after autonomous selfing was significantly lower than hand-selfed fruit set. Most SC species received insufficient pollen from themselves via autonomous selfing, and natural fruit set was mostly pollinator-mediated. Thus, the reproductive assurance provided by autonomous selfing is relatively low in comparison with that provided by pollinators. We supplemented our data with published results from different sites in South America, to assess how general are the associations between life form and compatibility system and between natural fruit production and the self compatibility index. There is a differential distribution of SC and SI species according to life form, with a skew towards incompatibility among woody plants and towards compatibility in herbs. On the other hand, regression analysis showed there is a general positive trend between natural fruit set and the self compatibility index of the species.     

Single‐nucleotide and long‐patch base excision repair of DNA damage in plants

Base excision repair (BER) is a critical pathway in cellular defense against endogenous or exogenous DNA damage. This elaborate multistep process is initiated by DNA glycosylases that excise the damaged base, and continues through the concerted action of additional proteins that finally restore DNA to the unmodified state. BER has been subject to detailed biochemical analysis in bacteria, yeast and animals, mainly through in vitro reproduction of the entire repair reaction in cell‐free extracts. However, an understanding of this repair pathway in plants has consistently lagged behind. We report the extension of BER biochemical analysis to plants, using Arabidopsis cell extracts to monitor repair of DNA base damage in vitro. We have used this system to demonstrate that Arabidopsis cell extracts contain the enzymatic machinery required to completely repair ubiquitous DNA lesions, such as uracil and abasic (AP) sites. Our results reveal that AP sites generated after uracil excision are processed both by AP endonucleases and AP lyases, generating either 5′‐ or 3′‐blocked ends, respectively. We have also found that gap filling and ligation may proceed either through insertion of just one nucleotide (short‐patch BER) or several nucleotides (long‐patch BER). This experimental system should prove useful in the biochemical and genetic dissection of BER in plants, and contribute to provide a broader picture of the evolution and biological relevance of DNA repair pathways.     

Families on the spot: sexual signals influence parent–offspring interactions

In 1950, Tinbergen described the elicitation of offspring begging by the red spot on the bill of parent gulls, and this became a model system for behavioural studies. Current knowledge on colour traits suggests they can act as sexual signals revealing individual quality. However, sexual signals have never been studied simultaneously in relationship to parent–offspring and sexual conflicts. We manipulated the red-spot size in one member of yellow-legged gull pairs and observed their partners'' feeding efforts in relationship to offspring begging. In the enlarged-spot group, partners doubled their effort compared with the other groups. Furthermore, in the reduced-spot group, partners provided food in relationship to offspring begging, contrasting with the fixed effort of the partners of enlarged-spot gulls. Manipulated gulls, independently of treatment, provided food in relationship to chicks begging only when the partner''s investment was low, and performed a fixed effort when the partner''s contribution was high. Results demonstrate that the red spot in yellow-legged gulls functions as a sexual signal and indicate that parental rules are plastic, depending on the information on offer. Previous evidence and this study indicate that this signal is used by all family members to adjust decision rules. The incorporation of sexual signals in parent–offspring interactions can be crucial in understanding intra-familial conflicts.     

Functional discrimination of sea anemone neurotoxins using 3D-plotting

One of the most important goals in structural biology is the identification of functional relationships among the structure of proteins and peptides. The purpose of this study was to (1) generate a model based on theoretical and computational considerations among amino acid sequences within select neurotoxin peptides, and (2) compare the relationship these values have to the various toxins tested. We employed isolated neurotoxins from sea anemones with established specific potential to act on voltage-dependent sodium and potassium channel activity as our model. Values were assigned to each amino acid in the peptide sequence of the neurotoxins tested using the Number of Lareo and Acevedo algorithm (NULA). Once the NULA number was obtained, it was then plotted using three dimensional space coordinates. The results of this study allow us to report, for the first time, that there is a different numerical and functional relationship between the sequences of amino acids from sea anemone neurotoxins, and the resulting numerical relationship for each peptide, or NULA number, has a unique location in three-dimensional space.     

Autosomal Resequence Data Reveal Late Stone Age Signals of Population Expansion in Sub-Saharan African Foraging and Farming Populations

Background

A major unanswered question in the evolution of Homo sapiens is when anatomically modern human populations began to expand: was demographic growth associated with the invention of particular technologies or behavioral innovations by hunter-gatherers in the Late Pleistocene, or with the acquisition of farming in the Neolithic?

Methodology/Principal Findings

We investigate the timing of human population expansion by performing a multilocus analysis of≥20 unlinked autosomal noncoding regions, each consisting of ∼6 kilobases, resequenced in ∼184 individuals from 7 human populations. We test the hypothesis that the autosomal polymorphism data fit a simple two-phase growth model, and when the hypothesis is not rejected, we fit parameters of this model to our data using approximate Bayesian computation.

Conclusions/Significance

The data from the three surveyed non-African populations (French Basque, Chinese Han, and Melanesians) are inconsistent with the simple growth model, presumably because they reflect more complex demographic histories. In contrast, data from all four sub-Saharan African populations fit the two-phase growth model, and a range of onset times and growth rates is inferred for each population. Interestingly, both hunter-gatherers (San and Biaka) and food-producers (Mandenka and Yorubans) best fit models with population growth beginning in the Late Pleistocene. Moreover, our hunter-gatherer populations show a tendency towards slightly older and stronger growth (∼41 thousand years ago, ∼13-fold) than our food-producing populations (∼31 thousand years ago, ∼7-fold). These dates are concurrent with the appearance of the Late Stone Age in Africa, supporting the hypothesis that population growth played a significant role in the evolution of Late Pleistocene human cultures.     

CFTR structure and function: is there a role in the kidney?

Cystic fibrosis (CF) is a lethal autosomal recessive genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR). Mutations in the CFTR gene may result in a defective protein processing that leads to changes in function and regulation of this chloride channel. Despite of the expression of CFTR in the kidney, patients with CF do not present major renal dysfunction, but it is known that both the urinary excretion of proteins and renal capacity to concentrate and dilute urine are altered in these patients. CFTR mRNA is expressed in all nephron segments of rat and human, and this abundance is more prominent in renal cortex and outer medulla renal areas. CFTR protein was detected in apical surface of both proximal and distal tubules of rat kidney but not in the outer medullary collecting ducts. Studies have demonstrated that CFTR does not only transport Cl⁻ but also ATP. ATP transport by CFTR could be involved in the control of other ion transporters such as Na⁺ (ENaC) and K⁺ (renal outer medullary potassium) channels, especially in TAL and CCD. In the kidney, CFTR also might be involved in the endocytosis of low-molecular-weight proteins by proximal tubules. This review is focused on the CFTR function and structure, its role in the renal physiology, and its modulation by hormones involved in the control of extracellular fluid volume.