A new actinomycete from a Guadalupian vertebrate coprolite from Brazil

Coprolites (fossil feces) are important sources of evidence of ancient food webs and ecosystems. Actinomycetes are a fundamental component in the decay of organic matter, and serve as catalysts for nutrient cycles. Recently, gas vesicles filled with numerous verrucose colonies of substrate mycelium of an actinomycete were discovered inside a fossilized spiral amphipolar fish coprolite recovered from mid–Permian deposits of Brazil. These colonies are composed of masses of substrate hyphae, some of which are undergoing segmentation. Arising from the colonies are chains of spores separated by narrow, elongate connectives. The fossil actinomycete is described below as Palaeostromatus diairetus gen. et sp. nov. and represents the oldest known actinomycete associated with vertebrate deposits. Since the colonies occur only inside the coprolite, either Palaeostromatus diairetus gen. et sp. nov. was part of the gut flora or it was acquired from a food source. The only other remains in the coprolite are eighteen paleoniscoid fish scales, which suggests that the producer was a carnivorous/omnivorous fish. This is the oldest record of a direct interaction between vertebrates and actinomycetes.     

Characterization of tetranucleotide microsatellites for Rio Grande cutthroat trout and rainbow trout,and their cross‐amplification in other cutthroat trout subspecies

We describe the isolation and characterization of 12 tetranucleotide microsatellites for Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis) and rainbow trout (Oncorhynchus mykiss), and subsequently investigate their performance in Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus), greenback cutthroat trout (Oncorhynchus clarkii stomias) and Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri). All 12 loci are polymorphic in all subspecies of O. clarkii examined.     

Bird assemblages on Amazonian river islands: Patterns of species diversity and composition

The principles of island biogeography are rarely applied to the animal assemblages of Amazonian river islands. Here, we compare bird assemblages of Amazonian river islands with a variety of mainland habitats. We also examine how bird species diversity and composition are related to island physical attributes. Birds were sampled with mist nets and qualitative censuses on 11 river islands and 24 mainland sites on the lower reaches of the Rio Negro in the Brazilian Amazon. Island bird assemblages were characterized by lower species richness and a higher abundance of a few dominant species. Additionally, the species composition of the islands was distinct from that of the mainland, including the nearby floodplain habitats. The number of bird species increased with island size and habitat diversity, and decreased with degree of isolation. In addition, small islands tended to harbor an impoverished subset of the species present on larger ones. Bird species diversity and composition on Amazonian river islands are likely influenced by the ecological succession and historical events affecting island formation. Considering their small total area across the Amazon basin, these insular fluvial communities could be disproportionately threatened by river channel disturbances related to climate change or hydroelectric dam development. Abstract in Portughese is available with online material.     

C : N : P stoichiometry of dominant riparian trees and arthropods along the Middle Rio Grande

1. We examined the role of flooding on the leaf nutrient content of riparian trees by comparing the carbon : nitrogen : phosphorus (C : N : P) ratio of leaves and litter of Rio Grande cottonwood (Populus deltoides ssp. wislizenii) in flood and non‐flood sites along the Middle Rio Grande, NM, U.S.A. The leaf C : N : P ratio was also examined for two non‐native trees, saltcedar (Tamarix chinensis) and Russian olive (Elaeagnus angustifolia), and six species of dominant riparian arthropods. 2. Living leaves and leaf litter of cottonwoods at flood sites had a significantly lower leaf N : P ratio and higher %P compared with leaves and litter at non‐flood sites. A non‐flood site downstream from wastewater effluent had a significantly lower litter C : N ratio than all other sites, suggesting N fertilisation through ground water. The non‐native trees, saltcedar and Russian olive, had higher mean leaf N content, N : P ratio, and lower C : N ratio compared with cottonwoods across study sites. 3. Riparian arthropods ranged from 5.2 to 7.1 for C : N ratio, 56–216 for C : P ratio, and 8.9–34 for N : P ratio. C content ranged from 25 to 52% of dry mass, N content from 4.7 to 10.8%, and P content from 0.59 to 1.2%. Differences in stoichiometry between high C : nutrient leaf litter and low C : nutrient invertebrates suggests possible food‐quality constraints for detritivores. 4. These results suggest that spatial and temporal variation in the C : N : P ratio of cottonwood leaves and leaf litter is influenced by surface and subsurface hydrologic connection within the floodplain. Reach‐scale variation in the elemental composition of riparian organic matter inputs may have important implications for decomposition, nutrient cycling, and food webs in river floodplain systems.     

Unsuccessful induction of low-zone tolerance to bovine serum albumin injected into the subarachnoid space

Introduction of T-dependent antigens into the subarachnoid space (isas) resulted in higher systemic antibody responses in mice than injections into the peritoneal cavity (ip) or other sites commonly used for immunization. Antibody production in isas immunized mice was not increased by treatment with cyclophosphamide (Cy) at doses known to abolish T-suppressor-cell activity, but such treatment increased antibody production in ip immunized mice toward the higher level which was observed in the isas immunized animals. Suppressor cell-dependent low zone tolerance (LZT) to TNP-BSA could not be induced by isas injections of deaggregated BSA (d-BSA). Conversely, mice which were unresponsive to ip injected d-BSA showed consistent systemic antibody responses when the antigen was injected isas. These observations indicate that immune responses initiated within the CNS are associated with relatively ineffective induction of systemic suppressor cell activity.     

Ritual production of environmental history among the Arawakan Wakuénai of Venezuela

This essay examines ritual and ceremonial activities among the Arawakspeaking Wakuénai of the Venezuelan Amazon as processes of constructing power relations in changing historical and ecological conditions. Ritual evocations of the vertical dimension of power relations between mythic ancestors and human descendants adapt local populations to conditions of relatively severe stress, such as epidemics and scarcity of fish in long wet seasons. Other rituals evoke the horizontal dimension of power relations between affinally-related groups as a way of expanding the local descent group in conditions of lowered stress. These two ways of exercising ritual power link human populations to specific natural habitats and provide flexibility needed to adjust to demographic and other historical changes. Through ritual performances, the Wakuénai transform the natural environment into a cultural landscape of socialized objects and, conversely, remember the history of political relations among peoples through spirit-naming of natural species, objects, places, and geographic landmarks.     

The Expression of Connexins and SOX2 Reflects the Plasticity of Glioma Stem-Like Cells

Glioblastoma (GBM) is the most malignant primary brain tumor, with an average survival rate of 15 months. GBM is highly refractory to therapy, and such unresponsiveness is due, primarily, but not exclusively, to the glioma stem-like cells (GSCs). This subpopulation express stem-like cell markers and is responsible for the heterogeneity of GBM, generating multiple differentiated cell phenotypes. However, how GBMs maintain the balance between stem and non-stem populations is still poorly understood. We investigated the GBM ability to interconvert between stem and non-stem states through the evaluation of the expression of specific stem cell markers as well as cell communication proteins. We evaluated the molecular and phenotypic characteristics of GSCs derived from differentiated GBM cell lines by comparing their stem-like cell properties and expression of connexins. We showed that non-GSCs as well as GSCs can undergo successive cycles of gain and loss of stem properties, demonstrating a bidirectional cellular plasticity model that is accompanied by changes on connexins expression. Our findings indicate that the interconversion between non-GSCs and GSCs can be modulated by extracellular factors culminating on differential expression of stem-like cell markers and cell-cell communication proteins. Ultimately, we observed that stem markers are mostly expressed on GBMs rather than on low-grade astrocytomas, suggesting that the presence of GSCs is a feature of high-grade gliomas. Together, our data demonstrate the utmost importance of the understanding of stem cell plasticity properties in a way to a step closer to new strategic approaches to potentially eliminate GSCs and, hopefully, prevent tumor recurrence.     

Sedimentation and pedogenesis in a Central Amazonian Black water basin

Sedimentation rates were estimated in a Central Amazonian Black-water inundation forest. Sediment deposition on the forest ground, remote from the river bed, during an annual flood period, is of the order of 1 to 10 tons per hectare, depending on water depth and duration of flooding. The sediments consisted of fine organic matter, kaolinite, quartz sands and biogenic particles of silica. Their genesis and deposition depend on the interplay between pedogenic, limnological and biological processes. Sediments derive primarily from the materials leached from the soils. Clay soils are the main source of dissolved silica, and the sandy soils are the main sources of organic coumpounds and mineral particles. The physical sedimentation of particles as quartz sand grains only occurs in the upper reaches of the studied river. In the flood plain, the sedimentation is due to the coagulation and deposition of combined mineral particles and humic substances, and to the biological precipitation of the silica leached from the soil by sponges.     

Urbanization and Mismatch with Protected Areas Place the Conservation of a Threatened Species at Risk

In this work, we report the predicted distribution of the threatened fluminense swallowtail butterfly, Parides ascanius (Cramer 1775), and correlate it to the presence of urban and protected areas within its range. The distribution was modeled using a genetic algorithm. The predicted distribution of the fluminense swallowtail shows high agreement within Rio de Janeiro state, in a near-continuous strip of 2,038,253 ha along the coastal lowlands, 17.8 percent of which is within urban areas. Only 8.7 percent (178,187 ha) of the remaining (nonurban) predicted model overlapped at least partially with protected areas (19 in all). Almost half of these protected areas also overlapped with urban areas, resulting in an additional loss of 58,751 ha. In seven of 19 protected areas, the distribution of P. ascanius was predicted by less than 50 percent of the models; five of the remaining protected areas are less restrictive reserves. Despite the wide distribution predicted by the models, only two of the observed occurrence points matched the predicted distribution within protected areas. Modeling threatened species distribution is a useful tool for highlighting gaps in networks of protected areas and should aid in planning to fill these gaps. However, in several developing countries with high biodiversity, there is insufficient basic biological information for many threatened species. In these cases, prospecting field studies are urgently needed.