Preferred proline puckerings in cis andtrans peptide groups: Implications for collagen stability

The interplay between side-chain and main-chain conformations is a distinctive characteristic of proline residues. Here we report the results of a statistical analysis of proline conformations using a large protein database. In particular, we found that proline residues with the preceding peptide bond in the cis state preferentially adopt a down puckering. Indeed, out of 178 cis proline residues, as many as 145 (81%) are down. By analyzing the 1-4 and 1-5 nonbonding distances between backbone atoms, we provide a structural explanation for the observed trend. The observed correlation between proline puckering and peptide bond conformation suggests a new mechanism to explain the reported shift of the cis-trans equilibrium in proline derivatives. The implications of these results for the current models of collagen stability are also discussed.     

Estimation by PLFA of Microbial Community Structure Associated with the Rhizosphere of Lygeum spartum and Piptatherum miliaceum Growing in Semiarid Mine Tailings

The objective of this study was to compare the microbial community composition and biomass associated with the rhizosphere of a perennial gramineous species (Lygeum spartum L.) with that of an annual (Piptatherum miliaceum L.), both growing in semiarid mine tailings. We also established their relationship with the contents of potentially toxic metals as well as with indicators of soil quality. The total phospholipid fatty acid (PLFA) amount was significantly higher in the rhizosphere soil of the annual species than in the rhizosphere soil of the perennial species. The fungal/bacterial PLFA ratio was significantly greater in the perennial species compared to the annual species. The fatty acid 16:1ω5c, the fungal/bacterial PLFA ratio and monounsaturated/saturated PLFA ratio were correlated negatively with the soluble contents of toxic metals. The cyc/prec (cy17:0 + cy19:0/16:1ω7 + 18:1ω7) ratio was correlated positively with the soluble contents of Pb, Zn, Al, Ni, Cd, and Cu. The results of the PLFA analysis for profiling microbial communities and their stress status of both the plant species indicate that perennial and annual gramineous species appear equally suitable for use in programmes of revegetation of semiarid mine tailings.     

Wood anatomy and carbon‐isotope discrimination support long‐term hydraulic deterioration as a major cause of drought‐induced dieback

Hydraulic impairment due to xylem embolism and carbon starvation are the two proposed mechanisms explaining drought‐induced forest dieback and tree death. Here, we evaluate the relative role played by these two mechanisms in the long‐term by quantifying wood‐anatomical traits (tracheid size and area of parenchyma rays) and estimating the intrinsic water‐use efficiency (iWUE) from carbon isotopic discrimination. We selected silver fir and Scots pine stands in NE Spain with ongoing dieback processes and compared trees showing contrasting vigour (declining vs nondeclining trees). In both species earlywood tracheids in declining trees showed smaller lumen area with thicker cell wall, inducing a lower theoretical hydraulic conductivity. Parenchyma ray area was similar between the two vigour classes. Wet spring and summer conditions promoted the formation of larger lumen areas, particularly in the case of nondeclining trees. Declining silver firs presented a lower iWUE than conspecific nondeclining trees, but the reverse pattern was observed in Scots pine. The described patterns in wood anatomical traits and iWUE are coherent with a long‐lasting deterioration of the hydraulic system in declining trees prior to their dieback. Retrospective quantifications of lumen area permit to forecast dieback in declining trees 2–5 decades before growth decline started. Wood anatomical traits provide a robust tool to reconstruct the long‐term capacity of trees to withstand drought‐induced dieback.     

Evolutionary conservation and network structure characterize genes of phenotypic relevance for mitosis in human

The impact of gene silencing on cellular phenotypes is difficult to establish due to the complexity of interactions in the associated biological processes and pathways. A recent genome-wide RNA knock-down study both identified and phenotypically characterized a set of important genes for the cell cycle in HeLa cells. Here, we combine a molecular interaction network analysis, based on physical and functional protein interactions, in conjunction with evolutionary information, to elucidate the common biological and topological properties of these key genes. Our results show that these genes tend to be conserved with their corresponding protein interactions across several species and are key constituents of the evolutionary conserved molecular interaction network. Moreover, a group of bistable network motifs is found to be conserved within this network, which are likely to influence the network stability and therefore the robustness of cellular functioning. They form a cluster, which displays functional homogeneity and is significantly enriched in genes phenotypically relevant for mitosis. Additional results reveal a relationship between specific cellular processes and the phenotypic outcomes induced by gene silencing. This study introduces new ideas regarding the relationship between genotype and phenotype in the context of the cell cycle. We show that the analysis of molecular interaction networks can result in the identification of genes relevant to cellular processes, which is a promising avenue for future research.     

Probiotics as an emerging therapeutic strategy to treat NAFLD: focus on molecular and biochemical mechanisms

Nonalcoholic fatty liver disease (NAFLD) is currently the most common liver disease worldwide, both in adults and in children. NAFLD is characterized by aberrant lipid storage in hepatocytes (hepatic steatosis) and inflammatory progression to nonalcoholic steatohepatitis. Evidences so far suggest that intrahepatic lipid accumulation does not always derive from obesity. Gut microbiota has been considered as a regulator of energy homeostasis and ectopic fat deposition, suggesting its implications in metabolic diseases. Probiotics are live microbial that alter the enteric microflora and have beneficial effects on human health. Although the molecular mechanisms of probiotics have not been completely elucidated yet, many of their effects have proved to be beneficial in NAFLD, including the modulation of the intestinal microbiota, an antibacterial substance production, an improved epithelial barrier function and a reduced intestinal inflammation. Given the close anatomical and functional correlation between the bowel and the liver, and the immunoregulatory effects elicited by probiotics, the aim of this review is to summarize today's knowledge about probiotics in NAFLD, focusing in particular on their molecular and biochemical mechanisms, as well as highlighting their efficacy as an emerging therapeutic strategy to treat this condition.     

Patterns of frugivory in the columnar cactus Pilosocereus leucocephalus

In the frugivory networks of many arid and semi‐arid Mesoamerican ecosystems, columnar cacti act as keystone species that produce fruits with a high content of water and nutrients attractive to numerous vertebrates. The aim of this investigation was to assess the fruit removal patterns of two guilds of frugivores on the fruits of the woolly torch Pilosocereus leucocephalus. We assessed fruit pulp removal in two ways: by estimating the consumption of seeds given the amount of pulp removed per visit and by estimating the percentage of pulp removal over time. We put exclosures on unripe, intact fruits to keep frugivores from removing material. Once ripe, we removed the exclosures and tracked animal visitation of 69 fruits using camera traps. We obtained a total of 2,162 hr of footage (14:47 hours of them with effective pulp removal). The highest number of visitors is that of diurnal species (n = 12, all birds) versus only four nocturnal (three bats, one rodent). The most effective species in pulp removal are birds. Bats play a modest role in frugivory of this cactus. The significance of this work is twofold: (a) birds and bats consume the fruit pulp of this cactus and likely disperse its seeds, and (b) although bats rank high in pulp removal effectiveness, birds as a guild far outweigh their importance in this system, as they are not only more frequent but also remove more pulp and seeds. Both groups are known to be important in cacti seed dispersal, and our findings are essential in understanding the population dynamics of the woolly torch and in elucidating its seed dispersal ecology.     

Large-scale preventive chemotherapy for the control of helminth infection in Western Pacific countries: six years later

In 2001, Urbani and Palmer published a review of the epidemiological situation of helminthiases in the countries of the Western Pacific Region of the World Health Organization indicating the control needs in the region. Six years after this inspiring article, large-scale preventive chemotherapy for the control of helminthiasis has scaled up dramatically in the region. This paper analyzes the most recent published and unpublished country information on large-scale preventive chemotherapy and summarizes the progress made since 2000. Almost 39 million treatments were provided in 2006 in the region for the control of helminthiasis: nearly 14 million for the control of lymphatic filariasis, more than 22 million for the control of soil-transmitted helminthiasis, and over 2 million for the control of schistosomiasis. In general, control of these helminthiases is progressing well in the Mekong countries and Pacific Islands. In China, despite harboring the majority of the helminth infections of the region, the control activities have not reached the level of coverage of countries with much more limited financial resources. The control of food-borne trematodes is still limited, but pilot activities have been initiated in China, Lao People's Democratic Republic, and Vietnam.     

Ternary complexes of Cu(II) ion with cimetidine and L-alanine

(Cu(CM)A)B(C6H5)4 and Cu(CM)A(OH) X H2O (CM = cimetidine and HA = L-alanine) were prepared and characterized by elemental analysis, TG-DTA, IR, and electronic spectral data and magnetic susceptibility measurements. The EPR spectrum of (Cu(CM)A)B(C6H5)4 shows a distorted octahedral environment for the Cu(II) ion.     

Aging exacerbates negative remodeling and impairs endothelial regeneration after balloon injury

Many older patients, because of their high prevalence of coronary artery disease, are candidates for percutaneous coronary interventions (PCI), but the effects of vascular aging on restenosis after PCI are not yet well understood. Balloon injury to the right carotid artery was performed in adult and old rats. Vascular smooth muscle cell (VSMC) proliferation, apoptotic cell death, together with Akt induction, telomerase activity, p27kip1, and endothelial nitric oxide synthase (eNOS) expression was assessed in isolated arteries. Neointima hyperplasia and vascular remodeling along with endothelial cell regeneration were also measured after balloon injury. Arteries isolated from old rats exhibited a significant reduction of VSMC proliferation and an increase in apoptotic death after balloon injury when compared with adult rats. In the vascular wall of adult rats, balloon dilation induced Akt phosphorylation, and this was barely present in old rats. In arteries from old rats, Akt-modulated cell cycle check points like telomerase activity and p27kip1 expression were decreased and increased, respectively, compared with adults. After balloon injury, old rats showed a significant reduction of neointima formation and an increased vascular negative remodeling compared with adults. These results were coupled by a marked delay in endothelial regeneration in aged rats, partially mediated by a decreased eNOS expression and phosphorylation. Interestingly, chronic administration of L-arginine prevented negative remodeling and improved reendothelialization after balloon injury in aged animals. A decreased neointimal proliferation, an impaired endothelial regeneration, and an increase in vascular remodeling after balloon injury were observed in aged animals. The molecular mechanisms underlying these responses seem to be a reduced Akt and eNOS activity.