The microenvironment of the ovarian follicle in the postpartum dairy cow: Effects on reagent transfer from cumulus cells to oocytes in vitro

This study's hypothesis was that the nutrient composition in follicular fluid (FF) of ovarian follicles in early lactating postpartum cows may influence reagent transfer from cumulus cells (CC) to the oocyte. To test this, concentrations of amino acids (AA), cholesterol, glucose, and nonesterified fatty acids were measured in FF from the largest antral follicles at Days 21 and 46 postpartum during which time, most animals were expected to have resumed ovulatory activity. From the range of concentrations measured, two media compositions (Lac and Half-Lac) were prepared to compare with medium 199 (M199). The AA and cholesterol concentrations in FF were on average, approximately 35% and greater than 1000% higher than in M199, respectively. The nonesterified fatty acids, but not glucose, concentrations also exceeded those in M199. The transfer of fluorescent dye from CC to oocytes in bovine cumulus-oocyte complexes incubated with and without phosphodiesterase inhibitors (dipyridamole and milrinone) and/or forskolin was assessed. Maximum dye accumulation in oocytes incubated in M199 occurred after 4 hours and was further increased (P < 0.001) by dipyridamole. The addition of dipyridamole to Lac, but not Half-Lac, media also increased dye accumulation. There were effects of media (P < 0.001), cholesterol (P < 0.001), and forskolin (P < 0.05) on dye accumulation but no effects of stearic or palmitic acid in either Lac or Half-Lac media. The addition of oleic acid in Half-Lac (P < 0.01), but not Lac, media inhibited dye accumulation. These results support the hypothesis that reagent transfer from CC to oocytes is compromised when the AA composition in FF is low, as sometimes occurs during early lactation.     

Detection of the edible ectomycorrhizal fungus Lyophyllum shimeji colonising seedlings of cultivated conifer species in New Zealand

Lyophyllum shimeji is an edible ectomycorrhizal fungus that is widely distributed in East Asia and also present in the northern regions of Europe. In Japan, L. shimeji is a culinary delicacy, considered amongst all edible mushrooms to have the best taste and to be second only to Tricholoma matsutake in price. Traditionally, fruiting bodies of L. shimeji have been collected from the wild but fruiting of L. shimeji is now relatively uncommon and cannot keep up with increasing consumer demand. As a result, methods for its cultivation are being developed for commercial production in Japan and other countries. In this work, techniques were developed to cultivate L. shimeji on coniferous seedlings using a pure culture inoculum. They resulted in successful mycorrhization of Pinus pinaster and Picea abies in only 8 to 10 months. As ectomycorrhizae of L. shimeji are difficult to identify morphologically, mycorrhization was confirmed using an L. shimeji-specific PCR diagnostic, which was designed following a phylogenetic analysis of the Lyophyllum section Difformia using DNA sequences of the internal transcribed spacer (ITS), intergenic spacer (IGS) and elongation factor 1-α (EF1-α) gene. L. shimeji is a member of the Lyophyllum decastes complex in section Difformia, which also includes Lyophyllum fumosum and L. decastes. This analysis confirmed the separation of L. shimeji from closely related Lyophyllum spp. and enabled its unambiguous detection using an IGS-based PCR diagnostic. This is the first report of successful mycorrhization of L. shimeji on P. pinaster and P. abies and provides an opportunity for its commercial cultivation on conifers in New Zealand.     

Characterisation of New Zealand Fusarium populations using a polyphasic approach differentiates the F. avenaceum/F. acuminatum/F. tricinctum species complex in cereal and grassland systems

The purpose of this study was to determine the diversity and prevalence of Fusarium species in a survey of cereal and grassland systems from the South Island of New Zealand by applying morphological and molecular techniques. Isolates were collected from soil, roots, and stems from 21 cereal and grassland sites. Ten Fusarium species were identified using morphological characters, including F. acuminatum, F. avenaceum, F. crookwellense, F. culmorum, F. equiseti, F. oxysporum, F. poae, F. pseudograminearum, F. sambucinum, and F. tricinctum. In general, their distribution was found to be unrelated to biogeographical location, although agricultural practice increased the overall diversity of Fusarium. Phylogenetic analyses were successfully used to identify morphologically similar isolates belonging to the F. avenaceum/F. acuminatum/F. tricinctum species complex and to resolve previously undetermined relationships amongst these species. Fifty-eight isolates classified as either F. avenaceum, F. acuminatum, or other closely related species as well as several well-characterised isolates from international culture collections were examined using DNA sequence data for β-tubulin (βTUB), translation elongation factor 1α (EF1α), and mitochondrial small subunit ribosomal RNA (mtSSU). Analyses of DNA sequence data from both βTUB and EF1α discriminated among isolates of F. avenaceum, F. acuminatum, and F. tricinctum and determined that these three distinct sequence groups formed a single clade. By contrast, mtSSU was unable to differentiate F. avenaceum from F. acuminatum and other closely related species believed to be F. tricinctum. Comparison of the EF1α sequences with the international FUSARIUM-ID database supported the identification of isolates in this study. As in other studies, F. avenaceum was found to be widespread in agricultural and native ecosystems. However, F. acuminatum in New Zealand was found only on non-wheat hosts. The reason for the absence of this wheat pathogen in cereal-based ecosystems in New Zealand remains unknown.     

Are compound leaves an adaptation to seasonal drought or to rapid growth? Evidence from the Amazon rain forest

Aim To assess the hypotheses that compound leaves of trees in the Amazon forest are an adaptation to drought and/or rapid growth. Location Amazon rain forest, South America. Methods Genera from 137 permanent forest plots spread across Amazonia were classified into those with compound leaves and those with simple leaves. Metrics of compound leaf prevalence were then calculated for each plot and regression models that accounted for spatial autocorrelation were used to identify associations between climate variables and compound leaf structure. We also tested for associations between compound leaf structure and a variety of ecological variables related to life history and growth strategies, including wood density, annual increase in diameter and maximum height. Results One plant family, Fabaceae, accounts for 53% of compound‐leaved individuals in the dataset, and has a geographical distribution strongly centred on north‐east Amazonia. On exclusion of Fabaceae from the analysis we found no significant support for the seasonal drought hypothesis. However, we found evidence supporting the rapid growth hypothesis, with possession of compound leaves being associated with faster diameter growth rates and lower wood densities. Main conclusion This study provides evidence that possession of compound leaves constitutes one of a suite of traits and life‐history strategies that promote rapid growth in rain forest trees. Our findings highlight the importance of carefully considering the geographical distribution of dominant taxa and spatial clustering of data points when inferring ecological causation from environment–trait associations.     

Long term effects of whole tree harvesting on soil carbon and nutrient sustainability in the UK

The practice of harvesting forest residues is rapidly increasing due to rising demand for renewable energy. However, major concerns have been raised about the sustainability of this practice and its net impact on long term soil ability to support forest productivity, particularly through second and subsequent rotations. In this study, soil chemical properties such as acidity, total N and C, available NO₃–N and NH₄–N and exchangeable cations were measured in all horizons in peaty gleys soils under one of the oldest experiments in Europe—a 28-year-old second rotation stand of Sitka spruce (Picea sitchensis), in Kielder forest, UK. Treatments included Whole Tree Harvesting (WTH—of all above ground biomass), Conventional stem-only harvesting (CH) of the first rotation crop, and repeated Fertilisation (FE) after the planting of the second rotation forest. This study demonstrates the soil changes underpinning the reduced second rotation tree productivity on these acidic upland sites under WTH, a further 18 years after the investigation by Proe and Dutch (1994). Overall, WTH increased soil acidity significantly (p < 0.05) and reduced soil base saturation whilst FE reduced soil acidity (p < 0.05) and increased soil base saturation as compared to CH. Soil moisture was significantly higher (p < 0.01) under WTH compared to CH and FE plots. There was no evidence that WTH decreased soil organic carbon (SOC) and soil nitrogen (N), but to the contrary there were significantly (p < 0.01) higher concentrations and stocks of total C and N in the WTH soils compared with CH and FE. The depletion of SOC and N in CH and FE plots was attributed to much higher soil mineralisation rates associated with the brash and fertilisation as compared to the WTH plots, where significantly less soil available NO₃–N (p < 0.01) was found. In the long term WTH on peaty gley soils appears positive for soil C and N storage. However, WTH had a long term negative impact on soil and tree nutrition of K⁺ and P, which are currently at deficient levels, but has had a stabilising effect on tree N nutrition as measured in twigs and needles. These results suggest that whilst WTH lead to a reduction in aboveground tree biomass compared to conventional harvest, these practices on selected soil types and certain sites may be beneficial for soil C and N sequestration. The overall findings of this study imply that cost benefit analyses for each site should be carried out before decisions are made on the appropriate type of forest operations (harvesting and replanting), considering both geology and soils in order to serve both environmental benefits, long term sustainability and the available biomass production for timber and biofuel.     

Global Conservation Significance of Ecuador's Yasuní National Park

Background

The threats facing Ecuador''s Yasuní National Park are emblematic of those confronting the greater western Amazon, one of the world''s last high-biodiversity wilderness areas. Notably, the country''s second largest untapped oil reserves—called “ITT”—lie beneath an intact, remote section of the park. The conservation significance of Yasuní may weigh heavily in upcoming state-level and international decisions, including whether to develop the oil or invest in alternatives.

Methodology/Principal Findings

We conducted the first comprehensive synthesis of biodiversity data for Yasuní. Mapping amphibian, bird, mammal, and plant distributions, we found eastern Ecuador and northern Peru to be the only regions in South America where species richness centers for all four taxonomic groups overlap. This quadruple richness center has only one viable strict protected area (IUCN levels I–IV): Yasuní. The park covers just 14% of the quadruple richness center''s area, whereas active or proposed oil concessions cover 79%. Using field inventory data, we compared Yasuní''s local (alpha) and landscape (gamma) diversity to other sites, in the western Amazon and globally. These analyses further suggest that Yasuní is among the most biodiverse places on Earth, with apparent world richness records for amphibians, reptiles, bats, and trees. Yasuní also protects a considerable number of threatened species and regional endemics.

Conclusions/Significance

Yasuní has outstanding global conservation significance due to its extraordinary biodiversity and potential to sustain this biodiversity in the long term because of its 1) large size and wilderness character, 2) intact large-vertebrate assemblage, 3) IUCN level-II protection status in a region lacking other strict protected areas, and 4) likelihood of maintaining wet, rainforest conditions while anticipated climate change-induced drought intensifies in the eastern Amazon. However, further oil development in Yasuní jeopardizes its conservation values. These findings form the scientific basis for policy recommendations, including stopping any new oil activities and road construction in Yasuní and creating areas off-limits to large-scale development in adjacent northern Peru.     

Mitochondrial sequence divergence among Antarctic killer whale ecotypes is consistent with multiple species

Recently, three visually distinct forms of killer whales (Orcinus orca) were described from Antarctic waters and designated as types A, B and C. Based on consistent differences in prey selection and habitat preferences, morphological divergence and apparent lack of interbreeding among these broadly sympatric forms, it was suggested that they may represent separate species. To evaluate this hypothesis, we compared complete sequences of the mitochondrial control region from 81 Antarctic killer whale samples, including 9 type A, 18 type B, 47 type C and 7 type-undetermined individuals. We found three fixed differences that separated type A from B and C, and a single fixed difference that separated type C from A and B. These results are consistent with reproductive isolation among the different forms, although caution is needed in drawing further conclusions. Despite dramatic differences in morphology and ecology, the relatively low levels of sequence divergence in Antarctic killer whales indicate that these evolutionary changes occurred relatively rapidly and recently.