Substantial lake core and other evidence shows accelerated soil erosion occurred in the Maya Lowl... more Substantial lake core and other evidence shows accelerated soil erosion occurred in the Maya Lowlands of Central America over ancient Maya history from 3000 to 1000 years ago. But we have little evidence of the wider network of the sources and sinks of that eroded sediment cascade. This study begins to solve the mystery of missing soil with new research and a synthesis of existing studies of tropical forest soils along slopes in NW Belize. The research aim is to understand soil formation, long-term human impacts on slopes, and slope stability over time and to explore ecological implications. We studied soils on seven slopes in tropical forest areas that have experienced intensive ancient human impacts and those with little ancient impacts. All of our soil catenas, except for one deforested from old growth two years before, contain evidence for about 1000 years of stable, tropical forest cover since Maya abandonment. We characterized the physical, chemical, and taxonomic characteristics of soils at crest-shoulder, backslopes, footslopes, and depression locations, analyzing typical soil parameters, chemical elements, and carbon isotopes (δ 13 C) in dated and undated sequences. Four footslopes or depressions in areas of high ancient occupation preserved evidence of buried, clay-textured soils covered by coarser sediment dating from the Maya Classic period. Three footslopes from areas with scant evidence of ancient occupation had little discernable deposition. These findings add to a growing corpus of soil toposequences with similar facies changes in footslopes and depressions that date to the Maya period. Using major elemental concentrations across a range of catenas, we derived a measure (Ca+Mg)/(Al+Fe+Mn) of the relative contributions of autochthonous and allochthonous materials and the relative age of soil catenas. We found very low ratios in clearly older,
This dissertation examines the variability in the ways a monumental space was accessed and used b... more This dissertation examines the variability in the ways a monumental space was accessed and used by its community at the site of La Milpa, northwest Belize, between Late Preclassic (ca. 400 BCE – 250 CE) and Terminal Classic periods (ca. 780/850 – 900 CE). An analysis of the literature concerning the study of ancient Maya public monumental spaces shows that these spaces are often perceived as the material extensions of a privileged social class. This paradigm has also fostered an interpretive framework that largely disregards the presence and agency of the non-elite majority of the ancient Maya population, who likely interacted with these same spaces in their own distinct, nuanced ways. Using practice and agency theories, landscape anthropology, and the study of commoners in ancient Maya society, I analyze the material culture present in and around Structure 3, a large pyramidal temple at the largest plaza at La Milpa, to examine how groups of people from various socioeconomic contexts used, accessed, and impacted this space over the course of the occupation of this site. In order to study patterns of access and use of Structure 3, I focused on the identification of activity areas. I employed excavations, artifact analysis, volumetric analysis, geochemical analysis through ICP-MS, and sediment micromorphology to recover as wide a dataset as possible for the examination of activity areas. The data collected from the research area shows that the space framed by Structure 3 was accessed and used by the La Milpa community in very distinct ways over its life-history. From a relatively narrow range of activities in the Late Preclassic to Early Classic periods (ca. 400 BCE – 600 CE), the level and variability of activities occurring in and around Structure 3 greatly increases in the second half of the Late Classic to the Terminal Classic periods (ca. 650/700 – 900 CE). The transformation in how Structure 3 was accessed and used in the second half of the Late Classic to the Terminal Classic periods was likely a product of the changing needs of a dynamic community undergoing dramatic demographic and political transformations in this period.Anthropolog
The measure of the "Mayacene," a microcosm of the Early Anthropocene that occurred from c. 3000 t... more The measure of the "Mayacene," a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the "Mayacene" are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3dominated tropical forest ecosystem. Paleosol sequences exhibit "Maya Clays," a facies that reflects a glut of rapidly eroded sediments that overlie "Ekluum" paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Mayaperiod soil strata that show elevated carbon isotope ratios ( 13 C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The "Mayacene" of c. 3,000 to 1,000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene. consequence of sandy texture rather than deep weathering. Distinct from these ecosystems are the wetland savannas dominated by sedges, found in the perennial wetlands of the coastal plain . The Maya region has a tropical wet and dry climate, influenced by the Intertropical Convergence Zone, the subtropical high, land-sea interactions, and the easterly trade winds. Annual rainfall varies tremendously, from ~500 mm on the NW coast to >4000 mm in the highlands. Mean annual temperature ranges from 26° C in January to 32° C through most of the summer. The wet season runs from June to December, with highest rainfall from July to September. The dry season usually spans January through May, with large moisture deficits from March through May. One variable too often ignored in studies of earth surface processes is water chemistry, because it is difficult to evaluate changes over time and because it leaves little record. We can only study the historical data we have, i.e. modern geologic factors that influence water characteristics, and indirect evidence from past land use. Most of the region is karst and groundwater flows through sulfate-rich, carbonate aquifers. Regional waters often have high ionic concentrations, particularly of calcium and sulfate, and have great potential for pollution caused by rapid runoff from human-disturbed surfaces under intensive land use (Luzzadder-Beach, 2000). Human interactions with the Mesoamerican landscape began before the Holocene . Organized forest clearance and agriculture in the Maya Lowlands of Central America began around 5000 BP , and spread throughout the region between 4000 and 3000 BP, in the Early Preclassic . Ancient Maya imprints on the landscape thus began in the Preclassic Period, around 3200 -1700 BP, a time has termed the Maya landnam, when population was largely rural, though permanent settlements increased in size and slash-and-burn agriculture was typical in the Middle Preclassic (3000 to 2400 BP). Population and land use surged in the late Preclassic (2400-1750 BP, Adams et al., 2004: 329), with a marked Terminal Preclassic population downturn at 1800 BP . Population fluctuated in some regions during the Early Classic (1750-1400 BP) with general political transformation around the central Mexican city of Teotihuacan , then grew strongly during the Late Classic Period from 1400 to 1100 BP, supported by widespread, intensified agriculture, land manipulation and conservation efforts in the form of terracing and water management . This period also saw agriculture expand into engineered wetland environments , underscoring the relationship between water resources and hydraulic Maya society . Population declined dramatically and settlements and agricultural fields were abandoned in many parts of the Maya world in the late and Terminal Classic into the Postclassic, from 1100 BP onward . Postclassic populations were smaller, less sedentary and had less impact on the landscape. A few communities like Lamanai in Belize persisted until the European Conquest . Abandoned Maya agricultural landscapes and urban sites of the Central Maya Lowlands began to return to forest in the Postclassic, and some landscapes recovered to full forest by the time of European arrival (Hodell et al., 2000: 32; This review of ancient Maya environmental impacts draws on multiple methods and proxy environmental variables to synthesize the data from a large region. We discuss each paleoenvironmental proxy variable and refer to the articles that describe its use in detail. For new data from our own soil and sediment work, we described soil profiles in USDA terms, including texture, structure, color, and HCl reaction but present only stratigraphic and carbon isotope data . For carbon isotope analysis, we collected soil samples in plastic bags and dried them. We sieved the samples to 2 mm (10 mesh), crushed and sieved 5 gram subsamples to 0.25 mm (60 mesh), and removed carbonates with 1 M HCl. Next, to remove calcium and magnesium carbonates, the lab immersed the samples in a water bath heated to 70 °C for at least 2 h. Next, we removed humic and fulvic acid fractions of the soil organic matter (SOM) by the alkaline pyrophosphate extraction method . The stable carbon isotope ratio (δ 13 C) of the remaining soil humin was measured with a Finnigan Delta Plus isotope-ratio mass spectrometer, connected to a Costech elemental analyzer (EAIRMS) . Recent articles discuss these laboratory methods in detail (Webb et al.,
Recently, two influenza A virus (FLUAV) genomes were identified in Central and South American bat... more Recently, two influenza A virus (FLUAV) genomes were identified in Central and South American bats. These sequences exhibit notable divergence from classical FLUAV counterparts, and functionally, bat FLUAV glycoproteins lack canonical receptor binding and destroying activity. Nevertheless, other features that distinguish these viruses from classical FLUAVs have yet to be explored. Here, we studied the viral nonstructural protein NS1, a virulence factor that modulates host signaling to promote efficient propagation. Like all FLUAV NS1 proteins, bat FLUAV NS1s bind double-stranded RNA and act as interferon antagonists. Unexpectedly, we found that bat FLUAV NS1s are unique in being unable to bind host p85, a regulatory subunit of the cellular metabolism-regulating enzyme, phosphoinositide 3-kinase (PI3K). Furthermore, neither bat FLUAV NS1 alone nor infection with a chimeric bat FLUAV efficiently activates Akt, a PI3K effector. Structure-guided mutagenesis revealed that the bat FLUAV NS1-p85 interaction can be reengineered (in a strain-specific manner) by changing two to four NS1 residues (96L, 99M, 100I, and 145T), thereby creating a hydrophobic patch. Notably, ameliorated p85-binding is insufficient for bat FLUAV NS1 to activate PI3K, and a chimeric bat FLUAV expressing NS1 with engineered hydrophobic patch mutations exhibits cell-type-dependent, but species-independent, propagation phenotypes. We hypothesize that bat FLUAV hijacking of PI3K in the natural bat host has been selected against, perhaps because genes in this metabolic pathway were differentially shaped by evolution to suit the unique energy use strategies of this flying mammal. These data expand our understanding of the enigmatic functional divergence between bat FLUAVs and classical mammalian and avian FLUAVs. IMPORTANCE The potential for novel influenza A viruses to establish infections in humans from animals is a source of continuous concern due to possible severe outbreaks or pandemics. The recent discovery of influenza Alike viruses in bats has raised questions over whether these entities could be a threat to humans. Understanding unique properties of the newly described bat influenza Alike viruses, such as their mechanisms to infect cells or how they manipulate host functions, is critical to assess their likelihood of causing disease. Here, we characterized the bat influenza Alike virus NS1 protein, a key virulence factor, and found unexpected functional divergence of this protein from counterparts in other influenza A viruses. Our study dissects the molecular changes required by bat influenza Alike virus NS1 to adopt classical influenza A virus properties and suggests consequences of bat influenza Alike virus infection, potential future evolutionary trajectories, and intriguing virushost biology in bat species.
ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from... more ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 t... more The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
Substantial lake core and other evidence shows accelerated soil erosion occurred in the Maya Lowl... more Substantial lake core and other evidence shows accelerated soil erosion occurred in the Maya Lowlands of Central America over ancient Maya history from 3000 to 1000 years ago. But we have little evidence of the wider network of the sources and sinks of that eroded sediment cascade. This study begins to solve the mystery of missing soil with new research and a synthesis of existing studies of tropical forest soils along slopes in NW Belize. The research aim is to understand soil formation, long-term human impacts on slopes, and slope stability over time and to explore ecological implications. We studied soils on seven slopes in tropical forest areas that have experienced intensive ancient human impacts and those with little ancient impacts. All of our soil catenas, except for one deforested from old growth two years before, contain evidence for about 1000 years of stable, tropical forest cover since Maya abandonment. We characterized the physical, chemical, and taxonomic characteristics of soils at crest-shoulder, backslopes, footslopes, and depression locations, analyzing typical soil parameters, chemical elements, and carbon isotopes (δ 13 C) in dated and undated sequences. Four footslopes or depressions in areas of high ancient occupation preserved evidence of buried, clay-textured soils covered by coarser sediment dating from the Maya Classic period. Three footslopes from areas with scant evidence of ancient occupation had little discernable deposition. These findings add to a growing corpus of soil toposequences with similar facies changes in footslopes and depressions that date to the Maya period. Using major elemental concentrations across a range of catenas, we derived a measure (Ca+Mg)/(Al+Fe+Mn) of the relative contributions of autochthonous and allochthonous materials and the relative age of soil catenas. We found very low ratios in clearly older,
This dissertation examines the variability in the ways a monumental space was accessed and used b... more This dissertation examines the variability in the ways a monumental space was accessed and used by its community at the site of La Milpa, northwest Belize, between Late Preclassic (ca. 400 BCE – 250 CE) and Terminal Classic periods (ca. 780/850 – 900 CE). An analysis of the literature concerning the study of ancient Maya public monumental spaces shows that these spaces are often perceived as the material extensions of a privileged social class. This paradigm has also fostered an interpretive framework that largely disregards the presence and agency of the non-elite majority of the ancient Maya population, who likely interacted with these same spaces in their own distinct, nuanced ways. Using practice and agency theories, landscape anthropology, and the study of commoners in ancient Maya society, I analyze the material culture present in and around Structure 3, a large pyramidal temple at the largest plaza at La Milpa, to examine how groups of people from various socioeconomic contexts used, accessed, and impacted this space over the course of the occupation of this site. In order to study patterns of access and use of Structure 3, I focused on the identification of activity areas. I employed excavations, artifact analysis, volumetric analysis, geochemical analysis through ICP-MS, and sediment micromorphology to recover as wide a dataset as possible for the examination of activity areas. The data collected from the research area shows that the space framed by Structure 3 was accessed and used by the La Milpa community in very distinct ways over its life-history. From a relatively narrow range of activities in the Late Preclassic to Early Classic periods (ca. 400 BCE – 600 CE), the level and variability of activities occurring in and around Structure 3 greatly increases in the second half of the Late Classic to the Terminal Classic periods (ca. 650/700 – 900 CE). The transformation in how Structure 3 was accessed and used in the second half of the Late Classic to the Terminal Classic periods was likely a product of the changing needs of a dynamic community undergoing dramatic demographic and political transformations in this period.Anthropolog
The measure of the "Mayacene," a microcosm of the Early Anthropocene that occurred from c. 3000 t... more The measure of the "Mayacene," a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the "Mayacene" are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3dominated tropical forest ecosystem. Paleosol sequences exhibit "Maya Clays," a facies that reflects a glut of rapidly eroded sediments that overlie "Ekluum" paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Mayaperiod soil strata that show elevated carbon isotope ratios ( 13 C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The "Mayacene" of c. 3,000 to 1,000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene. consequence of sandy texture rather than deep weathering. Distinct from these ecosystems are the wetland savannas dominated by sedges, found in the perennial wetlands of the coastal plain . The Maya region has a tropical wet and dry climate, influenced by the Intertropical Convergence Zone, the subtropical high, land-sea interactions, and the easterly trade winds. Annual rainfall varies tremendously, from ~500 mm on the NW coast to >4000 mm in the highlands. Mean annual temperature ranges from 26° C in January to 32° C through most of the summer. The wet season runs from June to December, with highest rainfall from July to September. The dry season usually spans January through May, with large moisture deficits from March through May. One variable too often ignored in studies of earth surface processes is water chemistry, because it is difficult to evaluate changes over time and because it leaves little record. We can only study the historical data we have, i.e. modern geologic factors that influence water characteristics, and indirect evidence from past land use. Most of the region is karst and groundwater flows through sulfate-rich, carbonate aquifers. Regional waters often have high ionic concentrations, particularly of calcium and sulfate, and have great potential for pollution caused by rapid runoff from human-disturbed surfaces under intensive land use (Luzzadder-Beach, 2000). Human interactions with the Mesoamerican landscape began before the Holocene . Organized forest clearance and agriculture in the Maya Lowlands of Central America began around 5000 BP , and spread throughout the region between 4000 and 3000 BP, in the Early Preclassic . Ancient Maya imprints on the landscape thus began in the Preclassic Period, around 3200 -1700 BP, a time has termed the Maya landnam, when population was largely rural, though permanent settlements increased in size and slash-and-burn agriculture was typical in the Middle Preclassic (3000 to 2400 BP). Population and land use surged in the late Preclassic (2400-1750 BP, Adams et al., 2004: 329), with a marked Terminal Preclassic population downturn at 1800 BP . Population fluctuated in some regions during the Early Classic (1750-1400 BP) with general political transformation around the central Mexican city of Teotihuacan , then grew strongly during the Late Classic Period from 1400 to 1100 BP, supported by widespread, intensified agriculture, land manipulation and conservation efforts in the form of terracing and water management . This period also saw agriculture expand into engineered wetland environments , underscoring the relationship between water resources and hydraulic Maya society . Population declined dramatically and settlements and agricultural fields were abandoned in many parts of the Maya world in the late and Terminal Classic into the Postclassic, from 1100 BP onward . Postclassic populations were smaller, less sedentary and had less impact on the landscape. A few communities like Lamanai in Belize persisted until the European Conquest . Abandoned Maya agricultural landscapes and urban sites of the Central Maya Lowlands began to return to forest in the Postclassic, and some landscapes recovered to full forest by the time of European arrival (Hodell et al., 2000: 32; This review of ancient Maya environmental impacts draws on multiple methods and proxy environmental variables to synthesize the data from a large region. We discuss each paleoenvironmental proxy variable and refer to the articles that describe its use in detail. For new data from our own soil and sediment work, we described soil profiles in USDA terms, including texture, structure, color, and HCl reaction but present only stratigraphic and carbon isotope data . For carbon isotope analysis, we collected soil samples in plastic bags and dried them. We sieved the samples to 2 mm (10 mesh), crushed and sieved 5 gram subsamples to 0.25 mm (60 mesh), and removed carbonates with 1 M HCl. Next, to remove calcium and magnesium carbonates, the lab immersed the samples in a water bath heated to 70 °C for at least 2 h. Next, we removed humic and fulvic acid fractions of the soil organic matter (SOM) by the alkaline pyrophosphate extraction method . The stable carbon isotope ratio (δ 13 C) of the remaining soil humin was measured with a Finnigan Delta Plus isotope-ratio mass spectrometer, connected to a Costech elemental analyzer (EAIRMS) . Recent articles discuss these laboratory methods in detail (Webb et al.,
Recently, two influenza A virus (FLUAV) genomes were identified in Central and South American bat... more Recently, two influenza A virus (FLUAV) genomes were identified in Central and South American bats. These sequences exhibit notable divergence from classical FLUAV counterparts, and functionally, bat FLUAV glycoproteins lack canonical receptor binding and destroying activity. Nevertheless, other features that distinguish these viruses from classical FLUAVs have yet to be explored. Here, we studied the viral nonstructural protein NS1, a virulence factor that modulates host signaling to promote efficient propagation. Like all FLUAV NS1 proteins, bat FLUAV NS1s bind double-stranded RNA and act as interferon antagonists. Unexpectedly, we found that bat FLUAV NS1s are unique in being unable to bind host p85, a regulatory subunit of the cellular metabolism-regulating enzyme, phosphoinositide 3-kinase (PI3K). Furthermore, neither bat FLUAV NS1 alone nor infection with a chimeric bat FLUAV efficiently activates Akt, a PI3K effector. Structure-guided mutagenesis revealed that the bat FLUAV NS1-p85 interaction can be reengineered (in a strain-specific manner) by changing two to four NS1 residues (96L, 99M, 100I, and 145T), thereby creating a hydrophobic patch. Notably, ameliorated p85-binding is insufficient for bat FLUAV NS1 to activate PI3K, and a chimeric bat FLUAV expressing NS1 with engineered hydrophobic patch mutations exhibits cell-type-dependent, but species-independent, propagation phenotypes. We hypothesize that bat FLUAV hijacking of PI3K in the natural bat host has been selected against, perhaps because genes in this metabolic pathway were differentially shaped by evolution to suit the unique energy use strategies of this flying mammal. These data expand our understanding of the enigmatic functional divergence between bat FLUAVs and classical mammalian and avian FLUAVs. IMPORTANCE The potential for novel influenza A viruses to establish infections in humans from animals is a source of continuous concern due to possible severe outbreaks or pandemics. The recent discovery of influenza Alike viruses in bats has raised questions over whether these entities could be a threat to humans. Understanding unique properties of the newly described bat influenza Alike viruses, such as their mechanisms to infect cells or how they manipulate host functions, is critical to assess their likelihood of causing disease. Here, we characterized the bat influenza Alike virus NS1 protein, a key virulence factor, and found unexpected functional divergence of this protein from counterparts in other influenza A viruses. Our study dissects the molecular changes required by bat influenza Alike virus NS1 to adopt classical influenza A virus properties and suggests consequences of bat influenza Alike virus infection, potential future evolutionary trajectories, and intriguing virushost biology in bat species.
ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from... more ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 t... more The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
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Papers by Debora C Trein