Effect of human disturbance on the structure and regeneration of forests in the Nevado de Toluca National Park, Mexico

Sample plots were established in the principal forest types in the the Nevado de Toluca National Park, Mexico including those dominated by Pinus hartwegii, Abies religiosa, Quercus laurina and Alnus jorullensis. The vertical structure was defined by three strata in the coniferous forests and two strata in the broadleaved forests. Timber harvesting in Abies religiosa and Quercus laurina forests and fires generated by humans in Pinus hartwegii forests impeded the recruitment of saplings. Mature trees were also heavily impacted by logging in Pinus hartwegii forests. On the contrary, Alnus jorullensis forests were increasing due to the disturbance of Pinus and Quercus forests, as well abandoned crop lands within the park. A combination of logging, uncontrolled fire, and grazing appears to be compromising the recruitment of important tree species in this national park. These factors, together with human settlements, have also increased the proportion of early successional species. Changes in forest structure from human disturbance indicate a need to control these activities if conservation goals are not to be compromised.     

Regeneration patterns of Eastern white pine (Pinus strobus L.) in hardwood-dominated forests in Virginia, USA

Eastern white pine (Pinus strobus L.) is a moderately shade-tolerant species that co-occurs with hardwood tree species in many forests of the eastern United States, as well as in pure stands. The species is valued for its timber, as well as for wildlife and recreation. Regeneration of this species is somewhat unpredictable and often occurs in patches of similarly-aged cohorts. We described the regeneration patterns of this species and examined their relation to environmental variables within hardwood forests of southwestern Virginia, USA. An average of 5.3 white pine patches per ha were observed in this study. The majority of patches consisted of saplings (85%), with 9% of patches in pole size classes, and 6% in seedling size classes. The average density of patches was 43.5 stems with an average age of 20 years. The size of patches averaged 80.6 m². The total density of seedlings and the number of regeneration patches of all sizes of regeneration (seedlings, saplings, and poles) in plots was related to the surrounding density of large white pine trees (potential seed trees). The density of seedlings or patches was not significantly related to current vegetation cover or soil surface cover variables, but more than half of regeneration patches were located in or adjacent to old canopy gaps, most of which were old logging gaps. While seedling regeneration may occur within the understory of these forests near seed trees, advancement to the sapling and pole stage appears to be associated with canopy gap formation.     

Safety evaluation of an oak-flavored milk powder containing ellagitannins upon oral administration in the rat

Ellagitannins are phenolic compounds that occur in a number of dietary sources such as walnuts, raspberries, pomegranate, strawberries, and oak-aged wines. Ellagitannins have been acknowledged to have antioxidant and cancer chemopreventive activities. However, ellagitannins have also been considered to be "antinutrients" and have been reported to provoke adverse effects in animals. In this context, risk assessment studies are demanded to ensure that chemicals present in food do not compromise food safety. Oak-flavored milk can be obtained by thermal treatment of milk in the presence of oak shavings. The oak-flavored milk can be used to impart wood-like flavor to different recipes. The present study evaluated, under a subchronic approach, the safety of an oak-flavored milk powder containing ellagitannins in rats upon repeated oral administration for 96 days. The effect of 30% oak-flavored milk powder in the diet was evaluated. This amount involved a margin of safety equivalent to the daily intake of 134 yogurts by a 70 kg person for 96 days. Growth rate, food utility index, 9 hematological, and 13 serobiochemical parameters as well as the metabolism and tissue distribution of ellagitannins and derived metabolites were studied. Overall, no significant differences were found in oak-milk-fed rats in any blood parameter analyzed. No effect was found on growth rate and food utility index. Urolithin A was identified in feces of rats fed oak-flavored milk and the glucuronide derivative in urine. No metabolites were found in the liver, kidney, or uterus. Histopathological analysis of liver and kidney corroborated the absence of toxicity. Therefore, these results suggest that the intake of the oak-flavored milk powder assayed in this study is safe and does not involve potential hazard to human health.     

Multivariate statistical analysis of mass spectra as a tool for the classification of the main humic substances according to their structural and conformational features

The aim of this work is to explore the suitability of the complementary use of mass spectra and the corresponding statistical analysis (principal components-Pareto analysis (PCA) and discriminant analysis (DA)) of these spectra to differentiate diverse humic samples as a function of their structural and conformational features. To this end, the mass spectra of humic samples belonging to the main humic fraction types (gray humic acid, brown humic acid, and fulvic acid) were obtained by electrospray ionization mass spectrometry (ESI-MS). The results obtained showed that the application of PCA yielded a clear separation between blanks and humic samples. However, a clear differentiation among the humic fraction types was not achieved. The DA of PCA data, however, yielded a clear separation among the humic substances (HS) samples belonging to each HS fraction type considered: gray humic acids, brown humic acids, and fulvic acids. These results showed that the mass spectra of each humic sample include characteristic mass/charge (m/z) distribution values that can be considered as a "fingerprint" representative of its specific structural features. Our results also indicate that, although the m/z values principally corresponded to single-charged ions, we cannot identify these molecular weight distributions with those of humic samples, since sample molecular fragmentation, as well as partial molecular ionization, cannot be ruled out under our experimental and instrumental conditions.     

Dichloromethane as a solvent for lipid extraction and assessment of lipid classes and fatty acids from samples of different natures

The usefulness of the solvent mixture dichloromethane/methanol for lipid extraction and the determination of lipid classes and fatty acids in samples of different natures was conducted. Two different extraction methods were compared, one containing chloroform/methanol, another containing dichloromethane/methanol. Total lipid extraction showed some minor differences but no variation in the lipid classes. Regarding the fatty acid profile, in Echium virescens seeds, 17 major fatty acids could be identified and quantified, and all were equally extracted when either solvent system was employed. In Echium acanthocarpum hairy roots, 17 major fatty acids were quantified, showing some statistical differences for one cell line in favor of chloroform. The data obtained from the liquid nutrient medium were also comparable. The cod roe sample showed 31 major fatty acids, showing no statistical differences between the two solvent systems. Contrarily, the CH 2Cl 2 method was able to extract 31 main fatty acids found in European seabass dorsal muscle more efficiently than the CHCl 3 method. The results indicate that, for lipid extraction and fatty acid assessment, dichloromethane/methanol can readily replace the commonly employed chloroform/methanol, thus avoiding the major health, security, and regulatory problems associated with the use of chloroform.     

A Comparison of the Effects of Two Prey Enrichment Media on Growth and Survival of Pacific Bluefin Tuna,Thunnus orientalis,Larvae

Three experiments were conducted to investigate the growth, survival, and standardized cohort biomass of Pacific bluefin tuna, Thunnus orientalis, larvae fed nutritionally enhanced prey during the first week of feeding using two commonly used, commercially available enrichment media, AlgaMac Enrich and Marine Glos. T. orientalis larvae exhibited exponential growth in standard length and dry weight. The daily specific growth rates in length and weight are the first reported for T. orientalis larvae and the averages ranged from 3.8 to 4.1% and 27.5%, respectively, for larvae in the AlgaMac treatment and from 4.1 to 6.1% and 31.5%, respectively, in the Marine Glos treatment. Average daily growth rates in length ranged from 0.16 to 0.23 mm/d for larvae in the AlgaMac treatment and from 0.17 to 0.27 mm/d for those in the Marine Glos treatment. Daily growth rates in length were similar to those reported for other tuna larvae reared in the laboratory but slower than most published estimates for larval tunas in situ at similar water temperatures. Mean prey number per gut was positively associated with mean prey level in the tank. Both enrichment media appear to be good sources of nutritional improvement of planktonic prey for T. orientalis larvae.     

Persistence and molecular evolution of Mycobacterium bovis population from cattle and wildlife in Doñana National Park revealed by genotype variation

The role of wildlife in tuberculosis epidemiology is being widely studied since it can affect the effectiveness of eradication campaigns in cattle. The health problem is enhanced when it concerns also wildlife welfare and biodiversity conservation. This study was performed to understand the epidemiology of Mycobacterium bovis population affecting livestock and wild animals in the Do?ana National Park using bacteriology and molecular characterisation techniques. Tuberculosis research was performed on 1209 cattle and wild animals (artiodactyla and carnivore) collected over 6 years in the Park. One hundred and sixty-three animals were found to be infected with M. bovis, comprising 7.96% of the cattle and 20.53% of the wild animals tested. Spoligotyping revealed nine patterns, being SB1232 and SB1230 the most prevalent (77.30% and 15.34% of infected animals, respectively). MIRU-VNTR analysis of a selected panel of 92 isolates showed eight different profiles, including several spoligotypes within the same MIRU-VNTR profile. The discriminatory capacity of both techniques in this panel was similar. The results obtained by combination of both techniques corroborate that wildlife species are infected with the M. bovis strains which are more prevalent in cattle and reveal their persistence. Genotype variation between isolates strongly suggests micro-evolutionary events in the M. bovis population in the same area. This study in the Do?ana National Park exposes the risk of introduction of domestic animals into wildlife areas when there is not a warranty of disease freedom, appropriate diagnostic techniques and control measures.     

Expression of toll-like receptor 2 (TLR2) in porcine leukocyte subsets and tissues

Toll-like receptors (TLR) are a group of pattern recognition molecules that play a crucial role in innate immunity. TLR2 recognises a variety of microbial components leading to the development of inflammatory and immune responses. To characterise the expression and functional properties of porcine TLR2 (pTLR2), we have raised a panel of monoclonal antibodies (mAb) against this molecule. Mouse 3T3 cell transfectants expressing pTLR2 were used for immunisation of mice. The specificity of these antibodies was confirmed by their reactivity with CHO cells transfected with pTLR2 but not with pTLR4 or with non-transfected cells. Using one of these mAbs, named 1H11, pTLR2 was found on cells of the innate immune system, including monocytes, macrophages, and granulocytes, but not on peripheral blood lymphocytes. Staining of tissue sections showed that pTLR2 is also expressed on epithelial cells lining the tracheobronchial and intestinal tracts, bile ducts in the liver and renal tubules, and on the basal layer of the epidermis. This distribution is consistent with a surveillance function at entry sites, allowing for early detection of microbial invasion.     

Bottled-Water Quality in Metropolitan Mexico City

Bacteriological and physico-chemical parameters of 265 samples from 39 brands sold in 5-gallon plastic and glass bottles and 2-5 L plastic containers were analyzed to determine the quality of bottled water distributed in Mexico City. Tests included fecal and total coliform counts, alkalinity, total hardness, chloride, calcium and magnesium concentrations, pH and conductivity. Correlation and cluster analyses and ANOVA were carried out, and a comparison made of the averages with the maximum permissible levels established in the Official Mexican Norms. Concerning the investigated parameters no differences (p > 0.05) between the brands were found. Physico-chemical parameters were studied and all the samples were within the permissible limits. Most samples taken from the 5-gallon containers exceeded the maximum bacteriological limits. It was concluded that the bacteriological quality of the brands studied was extremely variable. Appropriate sanitary measures, should be established to control this aspect.