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Fecal Microflora in Healthy Persons in a Preindustrial Region   总被引:4,自引:3,他引:1       下载免费PDF全文
Procedures for quantitating the fecal microflora of man were described. Special attention was given to criteria for characterizing the culturable aerobic, Micro-aerophilic, and anaerobic bacteria. Three groups of healthy persons were studied: wholly breast-fed infants (2 to 4 month-olds), weanlings (1 to 2 year-olds), and adults. In breast-fed children, bifidobacteria predominate and outnumber by one or several logs all other culturable bacteria. The fecal flora of wholly breast-fed infants is "simpler" and more numerous [10(11) to 10(12) per g (wet weight) of feces than that of the adult 10(2) to 10(11) per g]. In the adult, gram-negative anaerobic bacilli (bacteroides) outnumber all other groups by a factor of 1 log or more. Weanlings receiving an adult-type diet, but still breast-fed, showed a flora intermediate between that of the wholly breast-fed infant and that of the adult, but more similar to the latter. Anaerobes always constitute the predominant component of the culturable flora of children and adults and are always found in large numbers under conditions of health. The aerobes are significantly less numerous, and vary widely in their number and in the frequency with which they appear in feces.  相似文献   
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Ecosystems - Frugivory and seed dispersal by fish is an important mutualistic interaction in complex and species-rich tropical rivers. The local ecological knowledge (LEK) held by fishers can...  相似文献   
4.
Population dynamics can be influenced by physical and biological factors, particularly in stressful environments. Introduced species usually have great physiological plasticity, resulting in populations with different traits. Undaria pinnatifida, a macroalga originally described from northeast Asia, was introduced in Northern Patagonia, Argentina (San Matías Gulf) around 2010. To describe the spatio-temporal variability in population structure and morphometry of U. pinnatifida, we conducted monthly field samplings for 2 years at the intertidal area of two contrasting sites in the San Matías Gulf. Individuals of U. pinnatifida were classified by developmental stage, and their morpho-gravimetric variables were measured. In both intertidal sites juveniles were found in higher proportion during austral autumn and grew and matured during the autumn-winter months (from May onwards), and individuals senesced during early austral summer (December and January). Conversely, density and biomass were largely different between sites, and individuals showed slight morphological variability between sites. Environmental (e.g., nutrient concentration, available substrate) and biological factors (e.g., facilitation, competition) may explain the observed differences. Since there is not a macroalga with U. pinnatifida morphometrical characteristics in the intertidal environments of San Matías Gulf, studying this recent introduction gives us a better understanding of its potential ecological effects.  相似文献   
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Reproducibility and reusability of the results of data-based modeling studies are essential. Yet, there has been—so far—no broadly supported format for the specification of parameter estimation problems in systems biology. Here, we introduce PEtab, a format which facilitates the specification of parameter estimation problems using Systems Biology Markup Language (SBML) models and a set of tab-separated value files describing the observation model and experimental data as well as parameters to be estimated. We already implemented PEtab support into eight well-established model simulation and parameter estimation toolboxes with hundreds of users in total. We provide a Python library for validation and modification of a PEtab problem and currently 20 example parameter estimation problems based on recent studies.  相似文献   
6.
Parallel evolution has been invoked as a forceful mechanism of ecotype and species formation in many animal taxa. However, parallelism may be difficult to separate from recently monophyletically diverged species that are likely to show complex genetic relationships as a result of considerable shared ancestral variation and secondary hybridization in local areas. Thus, species' degrees of reproductive isolation, barriers to dispersal and, in particular, limited capacities for long‐distance dispersal will affect demographical structures underlying mechanisms of divergent evolution. Here, we used nine microsatellite DNA markers to study intra‐ and interspecific genetic diversity of two recently diverged species of brown macroalgae, Fucus radicans (L. Bergström & L. Kautsky) and Fvesiculosus (Linnaeus), in the Baltic Sea. We further performed biophysical modelling to identify likely connectivity patterns influencing the species' genetic structures. For each species, we found intraspecific contrasting patterns of clonality incidence and population structure. In addition, strong genetic differentiation between the two species within each locality supported the existence of two distinct evolutionary lineages (FST = 0.15–0.41). However, overall genetic clustering analyses across both species' populations revealed that all populations from one region (Estonia) were more genetically similar to each other than to their own taxon from the other two regions (Sweden and Finland). Our data support a hypothesis of parallel speciation. Alternatively, Estonia may be the ancestral source of both species, but is presently isolated by oceanographic barriers to dispersal. Thus, a limited gene flow in combination with genetic drift could have shaped the seemingly parallel structure.  相似文献   
7.
The spread of multidrug resistant bacteria owing to the intensive use of antibiotics is challenging current antibiotic therapies, and making the discovery and evaluation of new antimicrobial agents a high priority. The evaluation of novel peptide sequences of predicted antimicrobial peptides from different sources is valuable approach to identify alternative antibiotic leads. Two strategies were pursued in this study to evaluate novel antimicrobial peptides from the human β-defensin family (hBD). In the first, a 32-residue peptide was designed based on the alignment of all available hBD primary structures, while in the second a putative 35-residue peptide, hBD10, was mined from the gene DEFB110. Both hBDconsensus and hBD10 were chemically synthesized, folded and purified. They showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Mycobacterium tuberculosis, but were not hemolytic on human red blood cells. The NMR-based solution structure of hBDconsensus revealed that it adopts a classical β-defensin fold and disulfide connectivities. Even though the mass spectrum of hBD10 confirmed the formation of three disulfide bonds, it showed limited dispersion in 1H NMR spectra and structural studies were not pursued. The evaluation of different β-defensin structures may identify new antimicrobial agents effective against multidrug-resistant bacterial strains.  相似文献   
8.
Prostate cancer (PCa) is a leading cause of death among males. It is currently estimated that inflammatory responses are linked to 15-20% of all deaths from cancer worldwide. PCa is dominated by complications arising from metastasis to the bone where the tumor cells interact with the bone microenvironment impairing the balance between bone formation and degradation. However, the molecular nature of this interaction is not completely understood. Heme oxygenase-1 (HO-1) counteracts oxidative damage and inflammation. Previous studies from our laboratory showed that HO-1 is implicated in PCa, demonstrating that endogenous HO-1 inhibits bone derived-prostate cancer cells proliferation, invasion and migration and decreases tumor growth and angiogenesis in vivo. The aim of this work was to analyze the impact of HO-1 modulated PCa cells on osteoblasts proliferation in vitro and on bone remodeling in vivo. Using a co-culture system of PC3 cells with primary mice osteoblasts (PMOs), we demonstrated that HO-1 pharmacological induction (hemin treatment) abrogated the diminution of PMOs proliferation induced by PCa cells and decreased the expression of osteoclast-modulating factors in osteoblasts. No changes were detected in the expression of genes involved in osteoblasts differentiation. However, co-culture of hemin pre-treated PC3 cells (PC3 Hem) with PMOs provoked an oxidative status and activated FoxO signaling in osteoblasts. The percentage of active osteoblasts positive for HO-1 increased in calvarias explants co-cultured with PC3 Hem cells. Nuclear HO-1 expression was detected in tumors generated by in vivo bone injection of HO-1 stable transfected PC3 (PC3HO-1) cells in the femur of SCID mice. These results suggest that HO-1 has the potential to modify the bone microenvironment impacting on PCa bone metastasis.  相似文献   
9.

Background  

Bioleaching is a process that has been used in the past in mineral pretreatment of refractory sulfides, mainly in the gold, copper and uranium benefit. This technology has been proved to be cheaper, more efficient and environmentally friendly than roasting and high pressure moisture heating processes. So far the most studied microorganism in bioleaching is Acidithiobacillus ferrooxidans. There are a few studies about the benefit of metals of low value through bioleaching. From all of these, there are almost no studies dealing with complex minerals containing arsenopyrite (FeAsS). Reduction and/or elimination of arsenic in these ores increase their value and allows the exploitation of a vast variety of minerals that today are being underexploited.  相似文献   
10.
Animal toxins block voltage-dependent potassium channels (Kv) either by occluding the conduction pore (pore blockers) or by modifying the channel gating properties (gating modifiers). Gating modifiers of Kv channels bind to four equivalent extracellular sites near the S3 and S4 segments, close to the voltage sensor. Phrixotoxins are gating modifiers that bind preferentially to the closed state of the channel and fold into the Inhibitory Cystine Knot structural motif. We have solved the solution structure of Phrixotoxin 1, a gating modifier of Kv4 potassium channels. Analysis of the molecular surface and the electrostatic anisotropy of Phrixotoxin 1 and of other toxins acting on voltage-dependent potassium channels allowed us to propose a toxin interacting surface that encompasses both the surface from which the dipole moment emerges and a neighboring hydrophobic surface rich in aromatic residues.  相似文献   
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