Biology

Voluntary running is a robust inducer of adult hippocampal neurogenesis. Given that fatty acid synthase (FASN), the key enzyme for de novo fatty acid biosynthesis, is critically involved in proliferation of embryonic and adult neural stem cells, we hypothesized that FASN could mediate both exercise-induced cell proliferation in the subgranular zone (SGZ) of the dentate gyrus (DG) and enhancement of spatial learning and memory. In 20 week-old male mice, voluntary running-induced hippocampal-specific upregulation of FASN was accompanied also by hippocampal-specific accumulation of palmitate and stearate saturated fatty acids. In experiments addressing the functional role of FASN in our experimental model, chronic intracerebroventricular (i.c.v.) microinfusions of C75, an irreversible FASN inhibitor, and significantly impaired exercisemediated improvements in spatial learning and memory in the Barnes maze. Unlike the vehicle-injected mice, the C75 group adopted a non-spatial serial escape strategy and displayed delayed escape latencies during acquisition and memory tests. Furthermore, pharmacologic blockade of FASN function with C75 resulted in a significant reduction, compared to vehicle treated controls, of the number of proliferative cells in the DG of running mice as measured by immunoreactive to Ki-67 in the SGZ. Taken together, our data suggest that FASN plays an important role in exercise-mediated cognitive enhancement, which might be associated to its role in modulating exercise-induced stimulation of neurogenesis. Citation: Chorna NE, Santos-Soto IJ, Carballeira NM, Morales JL, de la Nuez J, et al. (2013) Fatty Acid Synthase as a Factor Required for Exercise-Induced Cognitive Enhancement and Dentate Gyrus Cellular Proliferation. PLoS ONE 8(11): e77845.

A key to 17 species in the genus Hygrocybe, subgenus Pseudohygrocybe, sections Coccineae and Neohygrocybe sensu Boertmann is provided for the Greater Antilles. Five new species and five taxa that are new reports for the region are described. The new species in section Coccineae are H. pseudoadonis, H. viridiphylla, and H. zonata. The new species in section Neohygrocybe are H. albomarginata and H. ovinoides. The new reports are H.

A key to six taxa of Hygrocybe, subgenus Hygrocybe, sections Chlorophanae and Hygrocybe is provided. One species is new and four species are reported for the first time from the Greater Antilles. The new species is H. chimaeroderma (section Chlarophanae). Hygrocybe acutoconica, H. calyptriformis and H. incolor (section Hygrocybe) are reported for the first time, and two new varieties, H. konradii var. antillana and H. calyptriformis var. domingensis (section Hygrocybe) are described. Three new combinations are made: H. acutoconica var. microspora, H. conica var. brevispora and H. luteistipes (section Hygrocybe).

Five new species of Psilocybe from the Ca ribbean are described: P. caribaea, P. egonii, P. subpsi locybioides, P. zapotecoantillarum and P. zapotecocari baea. All except P. zapotecocaribaea, which is known only from Martinique, are native to Puerto Rico. Psil ocybe guilartensis, previously described from Puerto Rico, is the most commonly collected species of Psil ocybe in Puerto Rico. New information on morphol ogy is provided for P. guilartensis, and an emendation of the species circumscription is presented.

A key to 17 species in the genus Hygrocybe, subgenus Pseudohygrocybe, sections Coccineae and Neohygrocybe sensu Boertmann is provided for the Greater Antilles. Five new species and five taxa that are new reports for the region are described. The new species in section Coccineae are H. pseudoadonis, H. viridiphylla, and H. zonata. The new species in section Neohygrocybe are H. albomarginata and H. ovinoides. The new reports are H.

Most of the fungal diversity studies that have used a systematic collecting scheme have not included the discomycetes, so optimal sampling methods are not available for this group. In this study, I tested two sampling methods at each sites in the Caribbean National Forest, Puerto Rico and Ebano Verde Reserve, Dominican Republic. For a plot-based sampling method, 10 × 10 m plots were established and divided into one hundred 1 × 1 m subplots. For each sample, 12 subplots were selected at random with replacement. For a transect-based sampling method, 60 m long transects were established with twelve 1 × 1 m subplots randomly placed on either side of the transect line at 5 m intervals at the beginning of the study. The study was conducted from October 2001 to September 2002. For Puerto Rico, 46 and 51 morpho-species were identified in the transects and plots, respectively. There was a 32% overlap (68% complementarity) between sites. The Sorensen Similarity Coefficient between sites was 0.50 for both methods, and 0.55-0.63 between methods within sites. For the Dominican Republic, 25 and 26 morpho-species were identified in the transects and plots, respectively. There was a 24-31% overlap (69-76% complementarity) between sites. The Sørensen Similarity Coefficient between sites was 0.40-0.47 for transects and plots, respectively, and 0.40-0.70 between methods within sites. The species accumulation curve indicates that the minimum number of subplots needed is 10 per transect and 60-70 per plot to obtain between 70-80% of the species. In terms of sampling effort, I concluded that at least 12 samples distributed throughout a year but with shorter intervals during the rainy season are needed. There was no difference between using transects or plots based on the number of species and similarity indexes. Based on a Chi-Square analysis using the frequencies of species, however, transects were better that plots because the distribution of species is more homogeneous.

Hurricanes are an important disturbance in the tropics that can alter forest ecosystem properties and processes. To understand the immediate influence of hurricane disturbance on carbon cycling, we examined soil labile organic carbon (LOC) in a Canopy Trimming Experiment (CTE) located in the Luquillo Experimental Forest of Puerto Rico. We trimmed tree canopy and deposited debris (CTDD) on the forest ground of the treatment plots in December 2014, and collected floor mass samples and 0–10 cm soil samples three weeks before the treatment, as well as at scheduled intervals for 120 weeks after the treatment. Within the first week following the CTDD treatment, the mean soil microbial biomass carbon (MBC) and soil LOC in the CTDD plots were significantly greater than in the control plots (soil MBC: 2.56 g/kg versus 1.98 g/kg, soil LOC: 9.16 g/kg versus 6.44 g/kg, respectively), and the mean turnover rates of soil LOC in the CTDD plots were significantly faster than in the control plots. T...

Fungi were documented in tropical hypersaline microbial mats and their role in the degradation of complex carbohydrates (exopolymeric substance-EPS) was explored. Fungal diversity is higher during the wet season with Acremonium, Aspergillus, Cladosporium, and Penicillium among the more common genera. Diversity is also higher in the oxic layer and in young and transient mats. Enrichments with xanthan (a model EPS) show that without antibiotics (full community) degradation is faster than enrichments with antibacterial (fungal community) and antifungal (bacterial community) agents, suggesting that degradation is performed by a consortium of organisms (bacteria and fungi). The combined evidence from all experiments indicates that bacteria carried out approximately two-third of the xanthan degradation. The pattern of degradation is similar between seasons and layers but degradation is faster in enrichments from the wet season. The research suggests that fungi thrive in these hypersaline consortia and may participate in the carbon cycle through the degradation of complex carbohydrates.

In this study, we determine differences in total biomass of soil microorganisms and community structure (using the most probable number of bacteria (MPN) and the number of fungal genera) in patterned ground features (PGF) and adjacent vegetated soils (AVS) in mesic sites from three High Arctic islands in order to characterize microbial dynamics as affected by cryoturbation, and a broad bioclimatic gradient. We also characterize total biomass of soil microorganisms and the most probable number of bacteria along a topographic gradient within each bioclimatic subzone to evaluate whether differences in topography lead to differences in microbial dynamics at a smaller scale. We found total microbial biomass C, the most probable number of heterotrophic bacteria, and fungal genera vary along this bioclimatic gradient. Microbial biomass C decreased with increasing latitude. Overall, microbial biomass C, MPN and the number of fungal isolates were higher in AVS than in PGFs. The effects which topographic position had on microbial biomass C varied across the bioclimatic gradient as there was no effect of topographic position in Isachsen (subzone A) and Mould Bay (subzone B), when compared to Green Cabin (subzone C, warmer site).There was no effect of topographic position on MPN counts at Mould Bay and Green Cabin. However, in Isachsen, MPN counts were highest in the wet topographic position as compared to the mesic and dry. In conclusion, PGFs seem to decouple the effect climate that might have on the total biomass of soil microorganisms along the bioclimatic gradient; and influence gets ameliorated as latitude increases. Similarly, the effect of topography on the total microbial biomass is significant at the warmest bioclimatic zone of the gradient. Thus, climate and topographic effects on total microbial biomass increase with warmer climate.

In this study, we determine differences in total biomass of soil microorganisms and community structure (using the most probable number of bacteria (MPN) and the number of fungal genera) in patterned ground features (PGF) and adjacent vegetated soils (AVS) in mesic sites from three High Arctic islands in order to characterize microbial dynamics as affected by cryoturbation, and a broad bioclimatic gradient. We also characterize total biomass of soil microorganisms and the most probable number of bacteria along a topographic gradient within each bioclimatic subzone to evaluate whether differences in topography lead to differences in microbial dynamics at a smaller scale. We found total microbial biomass C, the most probable number of heterotrophic bacteria, and fungal genera vary along this bioclimatic gradient. Microbial biomass C decreased with increasing latitude. Overall, microbial biomass C, MPN and the number of fungal isolates were higher in AVS than in PGFs. The effects which topographic position had on microbial biomass C varied across the bioclimatic gradient as there was no effect of topographic position in Isachsen (subzone A) and Mould Bay (subzone B), when compared to Green Cabin (subzone C, warmer site).There was no effect of topographic position on MPN counts at Mould Bay and Green Cabin. However, in Isachsen, MPN counts were highest in the wet topographic position as compared to the mesic and dry. In conclusion, PGFs seem to decouple the effect climate that might have on the total biomass of soil microorganisms along the bioclimatic gradient; and influence gets ameliorated as latitude increases. Similarly, the effect of topography on the total microbial biomass is significant at the warmest bioclimatic zone of the gradient. Thus, climate and topographic effects on total microbial biomass increase with warmer climate.

In this study, we used a replicated factorial design to separate the individual and interacting effects of two main components of a severe hurricane-canopy opening and green debris deposition on leaf litter decay in the tabonuco forest in the Luquillo Mountains of Puerto Rico. We quantify changes in percent mass remaining (PMR), the concentration and absolute amounts of various chemical elements using fresh (green) and senesced leaf litter contained in litterbags of two different mesh sizes. Mass loss was significantly slowed by canopy trimming. There was no significant effect of debris treatment on the PMR of the litter. Canopy trimming increased the percent of initial N, Al, Ca, Fe, and Mg remaining and decreased the percent of initial Mn remaining compared with not trimmed plots. Debris addition increased the percent of initial N and P remaining and decreased the percent of initial Al, and Fe remaining in the decomposing litter compared to no debris added plots. Of the elements studied, only Al and Fe accumulated above 100% of initial. Accumulation of Al and Fe in the canopy trimmed and no debris plots is most likely dominated by the adsorption of these ions onto the surfaces of the decaying litter. Overall, P showed a rapid initial loss during the first 0.2 yr followed by steady loss. Nitrogen was lost steadily from leaf litter. The PMR of fresh and senesced litter was significantly affected by mesh size, with a higher mass remaining in small mesh bags. Fresh litter decayed faster than senesced litter; following patterns of initial N and P concentrations (higher in the former litter type). We found a significantly negative correlation between the Margalef index of diversity for the litter arthropods contained in the litterbags and the PMR, suggesting functional complexity is an important determinant of decay in this forest. Our results imply hurricanes can differentially impact litter decomposition and associated nutrient release via canopy opening and litter inputs.

Microorganisms mediate most of the biogeochemical transformations that are critical for the functioning of ecosystems, including making nutrients available to plants through decomposition of organic matter, and transformations in the nitrogen cycle. There are relatively few studies, however, of microbial diversity or abundance along elevation gradients. Bryant et al. (2008) found that acidobacteria declined with elevation in the northwestern USA using PCR of 16S ribosomal DNA while Adair and Schwartz (2008) found that ammonia oxidizing bacteria varied with precipitation in semi-arid soils in Arizona, USA. In contrast, Collins and Cavigelli (2003) found that the number of fatty acids increased with elevation in arid southern California. Several studies of slime molds along elevation gradients in Puerto Rico and elsewhere showed that diversity and abundance were inversely related to elevation (

A mycological survey of Fusarium species was conducted in two rearing ponds of the prawn Macrobrachium rosenbergii (De Man) in southwestern Puerto Rico, from October 1989 to September 1990. Surface and bottom water samples were collected from each pond and processed by the membrane filtration technique. Air samples were collected around each pond by the plate exposure technique. Pentachloronitrobenzene Agar was used as isolation medium. Six species of Fusarium were identified: F. chlamydosporum, F. equiseti, F. moniliforme, F. semitectum, F. solani and F. subglutinans. The more frequent species in water and air samples were F. semitectum and F. equiseti. The distribution of species was not statistically different between surface and bottom water for each pond. A significant difference was found between air samples and water samples for pond 1, but not for pond 2. During the rainy season the total colony forming units (CFU) of Fusarium spp. decreased in air samples and increased in water samples. During months of higher wind velocity the total CFU increased in air samples. No significant correlation was found between the total CFU/500 ml in water samples and wind velocity. There were significant differences between the ponds, the surface and the bottom water of each pond and the air samples around the two ponds. R ESUMEN .-Se realizo una evaluacicon micologica de las especies de Fusarium en dos estanques para la crianza del langostino Macrobrachium rosenbergii (De Man) en el suroeste de Puerto Rico, desde octubre de 1989 hasta septiembre de 1990. En cada estanque se tomaron muestras de agua de la superficie y del fondo, las cuales fueron procesadas mediante el metodo de filtration por membrana. Muestras del ambiente aereo fueron tomadas en ambos estanques mediante exposition de platos Petri. El medio usado para aislar las especies fue el agar de Pentacloronitrobenceno. Seis especies de Fusarium fueron identificadas F. chlamydosporum, F. equiseti, F. moniliforme, F. semitectum, F. solani y F. subglutinans. Las especies mas frecuentes en agua y ambiente aereo fueron F. semitectum y F. equiseti. No hubo diferencia significativa entre la distribucion de las especies en las muestras de agua de superficie y fondo de ambos estanques. Si fue significativa la diferencia entre las muestras de ambiente aereo y agua del estanque 1, pero no en el estanque 2. El contaje total de colonias (CFU) de Fusarium spp. disminuyo en el ambiente aereo y aumento en el agua durante los meses de mayor lluvia. Durante los meses de mayor velocidad de viento el contaje total de Fusarium spp. aumento en el ambiente aereo. No hubo correlation significativa entre el contaje total en las muestras de agua y la velocidad de viento. Hubo diferencias significativas entre los estanques, entre superficie y fondo de cada estanque y entre el ambiente aereo de ambos estanques.

Fungi are important for maintaining fast rates of decomposition in low quality tropical leaf litter via immobilization and translocation of limiting nutrients from sources to sinks and conserving nutrients after disturbance. Tropical trees often have low nutrient to carbon ratios. Disturbances such as hurricanes and logging transfer a large mass of green leaves with high nutrient concentrations to the forest floor, but the associated opening of the canopy dries the litter, inhibiting basidiomycete fungi that play critical roles in lignin degradation and nutrient conservation. We conducted a replicated block factorial experiment designed to disentangle the individual and interactive effects of canopy opening and green debris deposition on phosphorus (P) content, mass loss and fungal connectivity in decomposing leaf cohorts in subtropical wet forest in the Luquillo Mountains of Puerto Rico. Though green leaves had higher P concentrations they did not decompose significantly faster than senesced leaves. Mass loss differed among treatments after 14, 40.5 and 53 weeks decomposition. Mass loss at 7 weeks was predicted by P concentration at 7 weeks; mass loss in senesced leaves at 14 weeks was predicted by abundance of fungal connections between the senesced litter cohort and forest floor at 7 weeks. Fungal connectivity and P accumulation at 7 weeks and mass loss of senesced leaves beginning at 14 weeks were significantly different from and lower in plots with trimmed canopy and no debris than in the untrimmed plots with debris. Litter moisture was previously found to be significantly lower under open than closed canopy, and we found that moisture was a significant predictor of fungal connectivity in both senesced and green leaves. Deposition of green leaves ameliorated the inhibitory effect of canopy opening on fungal connectivity between litter cohorts by retaining moisture; consequently fungal connectivity and mass loss in senescent leaves did not differ between the Trim + Debris and the control treatments. Phosphorus content of senesced leaves increased significantly by 7 weeks in both trimmed and untrimmed plots with added green debris and in the control plots. Based on mass balance calculations, both the underlying forest floor and overlying green leaves likely contributed P to the decomposing senesced leaf cohort. Fungal translocation of P through hyphal connections between litter cohorts explains some of the changes in P content. Though fungi were important in conserving P, most of the P that was likely leached from green leaves was not retained in the litter layer.

Understanding variation in tropical forest fungal populations and communities is important for assessing fungal biodiversity, as well as for understanding the regulatory roles fungi play in tropical forests. In wet tropical forests, the canopy is typically occupied by certain wood decomposers, endophytes, epiphylls, and pathogens. Aphyllophoraceous canopy fungi are a subset of species found in the understory. Marasmioid agarics in the understory often form extensive networks of rhizomorphs that trap litter; these and other aerial species are rare on the forest floor. Decomposers are stratified within the forest floor, with some species colonizing only fresh litter, others preferring decomposed litter, and others restricted to soil organic matter. Specificity to particular host substrates is frequent among tropical forest litter decomposers and contributes to spatial heterogeneity in fungal communities over the landscape. Litter basidiomycetes and microfungal communities in patches o...

Most of the fungal diversity studies that have used a systematic collecting scheme have not included the discomycetes, so optimal sampling methods are not available for this group. In this study, I tested two sampling methods at each sites in the Caribbean National Forest, Puerto Rico and Ebano Verde Reserve, Dominican Republic. For a plot-based sampling method, 10 × 10 m plots were established and divided into one hundred 1 × 1 m subplots. For each sample, 12 subplots were selected at random with replacement. For a transect-based sampling method, 60 m long transects were established with twelve 1 × 1 m subplots randomly placed on either side of the transect line at 5 m intervals at the beginning of the study. The study was conducted from October 2001 to September 2002. For Puerto Rico, 46 and 51 morpho-species were identified in the transects and plots, respectively. There was a 32% overlap (68% complementarity) between sites. The Sorensen Similarity Coefficient between sites was 0.50 for both methods, and 0.55-0.63 between methods within sites. For the Dominican Republic, 25 and 26 morpho-species were identified in the transects and plots, respectively. There was a 24-31% overlap (69-76% complementarity) between sites. The Sørensen Similarity Coefficient between sites was 0.40-0.47 for transects and plots, respectively, and 0.40-0.70 between methods within sites. The species accumulation curve indicates that the minimum number of subplots needed is 10 per transect and 60-70 per plot to obtain between 70-80% of the species. In terms of sampling effort, I concluded that at least 12 samples distributed throughout a year but with shorter intervals during the rainy season are needed. There was no difference between using transects or plots based on the number of species and similarity indexes. Based on a Chi-Square analysis using the frequencies of species, however, transects were better that plots because the distribution of species is more homogeneous.