scholarly journals Soil Protists in Three Neotropical Rainforests are Hyperdiverse and Dominated by Parasites

2016 ◽  
Author(s):  
Frédéric Mahé ◽  
Colomban de Vargas ◽  
David Bass ◽  
Lucas Czech ◽  
Alexandros Stamatakis ◽  
...  
Keyword(s):  
Terrestrial Ecosystems ◽  
Tree Diversity ◽  
Tropical Tree ◽  
Tropical Rainforests ◽  
Dependent Manner ◽  
Unicellular Eukaryotes ◽  
Animal Diversity ◽  
Specific Manner ◽  
Neotropical Rainforest ◽  
Soil Protists

ABSTRACTAnimal and plant richness in tropical rainforests has long intrigued naturalist. More recent work has revealed that parasites contribute to high tropical tree diversity (Bagchi et al., 2014; Terborgh, 2012) and that arthropods are the most diverse eukaryotes in these forests (Erwin, 1982; Basset et al., 2012). It is unknown if similar patterns are reflected at the microbial scale with unicellular eukaryotes or protists. Here we show, using environmental metabarcoding and a novel phylogeny-aware cleaning step, that protists inhabiting Neotropical rainforest soils are hyperdiverse and dominated by the parasitic Apicomplexa, which infect arthropods and other animals. These host-specific protist parasites potentially contribute to the high animal diversity in the forests by reducing population growth in a density-dependent manner. By contrast, we found too few Oomycota to broadly drive high tropical tree diversity in a host-specific manner under the Janzen-Connell model (Janzen, 1970; Connell, 1970). Extremely high OTU diversity and high heterogeneity between samples within the same forests suggest that protists, not arthropods, are the most diverse eukaryotes in tropical rainforests. Our data show that microbes play a large role in tropical terrestrial ecosystems long viewed as being dominated by macro-organisms.Contact: [email protected]

scholarly journals Precipitation effects on soil characteristics in tropical rain forests of the Chocó biogeographical region

2016 ◽  
Vol 69 (1) ◽  
pp. 7813-7823 ◽  
Author(s):  
Harley Quinto Mosquera ◽  
Flavio Moreno Hurtado
Keyword(s):  
Terrestrial Ecosystems ◽  
Exchange Capacity ◽  
The Other ◽  
Tropical Rainforests ◽  
Curvilinear Relationship ◽  
Tropical Rain Forests ◽  
Total N ◽  
P Content ◽  
Biogeographical Region ◽  
Average Annual Precipitation

Average annual precipitation (AAP) is one of the principal environmental factors that regulates processes in terrestrial ecosystems. The effect of AAP on the availability of edaphic nutrients is poorly understood, especially in tropical zones with high rainfall. In order to evaluate the effects of high AAP on the availability of soil N, P, and K, physicochemical parameters were measured in soils of three tropical rainforests in the Chocó biogeographical region with different AAPs (7,500, 8,000, and 10,000 mm yr-1). Furthermore, a bibliographical review was carried out that including studies for distinct tropical Ultisols and AAP ranging from 1,800 to 10,000 mm yr-1. The evaluated soils presented extreme acidity with high contents of Al, organic matter (OM) and total N, and low quantities of P, Mg, and Ca. The K concentrations were intermediate and the effective cation exchange capacity (ECEC) was low. On the other hand, in the evaluation of the influence of the AAP on the availability of N, P, and K in the soil, contrasting tendencies were observed. On one side, a positive curvilinear relationship was found between the availability of N and the increase in the AAP. On the other side, the available P content significantly decreased with increasing AAP. In conclusion, the excessive AAP resulted in increases in total N and low availability of P, thereby altering the dynamics of the nutrients and the carbon balance of the tropical forest

Tropical Forests Natural History, Diversity, and Potentiality as Theatres of Human Adaptation and Negotiation

2019 ◽  
Author(s):  
Patrick Roberts
Keyword(s):  
Tropical Forest ◽  
Tropical Forests ◽  
Homo Sapiens ◽  
Terrestrial Ecosystems ◽  
Black Pepper ◽  
Wood Products ◽  
Tropical Rainforests ◽  
Cultural Significance ◽  
Seasonally Dry ◽  
Dry Tropical Forests

The above quote by the German poet, novelist, and painter Herman Hesse highlights the cultural significance of forests in nineteenth- and twentieth-century western culture as the ‘natural’ contrast to growing urban populations and industrial expansion. Hesse’s focus on the ‘ancient’ element of these environments is certainly valid in a tropical context, given that tropical forests are some of the oldest land-based environments on the planet, existing for over one thousand times longer than Homo sapiens (Upchurch and Wolf, 1987; Davis et al., 2005; Ghazoul and Shiel, 2010; Couvreur et al., 2011). This antiquity also makes them one of the richest and most diverse terrestrial ecosystems on the planet (Whitmore, 1998; Ghazoul and Shiel, 2010). Tropical rainforests, for example, contain over half of the world’s existing plant, animal, and insect species (Wilson, 1988). A significant portion of the developed world’s diet today originated in tropical forests—including staples such as squash and yams, spices such as black pepper, cinnamon, cloves, and sugar cane, and fruits including bananas, coconuts, avocados, mangoes, and tomatoes (Iriarte et al., 2007; Roberts et al., 2017a). Tropical forests also often provide ample freshwater for their inhabitants. However, despite popular perceptions of forests, and specifically tropical forests, as uniform, they are, in fact, highly variable across space and time. In tropical evergreen rainforests productivity is often primarily allocated to wood products, meaning that edible plants and animals for human subsistence have been considered lacking, or at least more difficult to extract, relative to more open tropical forest formations (Whitmore, 1998; Ghazoul and Shiel, 2010). Similarly, while evergreen tropical rainforests generally receive significant precipitation and freshwater, seasonally dry tropical forests are subject to sub-annual periods of aridity. Therefore, while archaeologists and anthropologists have tended to see ‘tropical forest’ as a uniform environmental block, it is important to explore the diversity within this category.

scholarly journals The rhizobial autotransporter determines the symbiotic nitrogen fixation activity of Lotus japonicus in a host-specific manner

2020 ◽  
Vol 117 (3) ◽  
pp. 1806-1815 ◽  
Author(s):  
Yoshikazu Shimoda ◽  
Yuki Nishigaya ◽  
Hiroko Yamaya-Ito ◽  
Noritoshi Inagaki ◽  
Yosuke Umehara ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Host Plant ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Dependent Manner ◽  
Strain Specificity ◽  
Passenger Domain ◽  
Aspartic Peptidase ◽  
Specific Manner

Leguminous plants establish endosymbiotic associations with rhizobia and form root nodules in which the rhizobia fix atmospheric nitrogen. The host plant and intracellular rhizobia strictly control this symbiotic nitrogen fixation. We recently reported a Lotus japonicus Fix− mutant, apn1 (aspartic peptidase nodule-induced 1), that impairs symbiotic nitrogen fixation. APN1 encodes a nodule-specific aspartic peptidase involved in the Fix− phenotype in a rhizobial strain-specific manner. This host-strain specificity implies that some molecular interactions between host plant APN1 and rhizobial factors are required, although the biological function of APN1 in nodules and the mechanisms governing the interactions are unknown. To clarify how rhizobial factors are involved in strain-specific nitrogen fixation, we explored transposon mutants of Mesorhizobium loti strain TONO, which normally form Fix− nodules on apn1 roots, and identified TONO mutants that formed Fix+ nodules on apn1. The identified causal gene encodes an autotransporter, part of a protein secretion system of Gram-negative bacteria. Expression of the autotransporter gene in M. loti strain MAFF3030399, which normally forms Fix+ nodules on apn1 roots, resulted in Fix− nodules. The autotransporter of TONO functions to secrete a part of its own protein (a passenger domain) into extracellular spaces, and the recombinant APN1 protein cleaved the passenger protein in vitro. The M. loti autotransporter showed the activity to induce the genes involved in nodule senescence in a dose-dependent manner. Therefore, we conclude that the nodule-specific aspartic peptidase, APN1, suppresses negative effects of the rhizobial autotransporter in order to maintain effective symbiotic nitrogen fixation in root nodules.

scholarly journals Dynamics of mitochondrial inheritance in the evolution of binary mating types and two sexes

2013 ◽  
Vol 280 (1769) ◽  
pp. 20131920 ◽  
Author(s):  
Zena Hadjivasiliou ◽  
Nick Lane ◽  
Robert M. Seymour ◽  
Andrew Pomiankowski
Keyword(s):  
Relative Fitness ◽  
Uniparental Inheritance ◽  
Dependent Manner ◽  
Mating Types ◽  
Mitochondrial Mutation ◽  
Unicellular Eukaryotes ◽  
Fitness Advantage ◽  
Mitochondrial Population ◽  
Fitness Benefits

The uniparental inheritance (UPI) of mitochondria is thought to explain the evolution of two mating types or even true sexes with anisogametes. However, the exact role of UPI is not clearly understood. Here, we develop a new model, which considers the spread of UPI mutants within a biparental inheritance (BPI) population. Our model explicitly considers mitochondrial mutation and selection in parallel with the spread of UPI mutants and self-incompatible mating types. In line with earlier work, we find that UPI improves fitness under mitochondrial mutation accumulation, selfish conflict and mitonuclear coadaptation. However, we find that as UPI increases in the population its relative fitness advantage diminishes in a frequency-dependent manner. The fitness benefits of UPI ‘leak’ into the biparentally reproducing part of the population through successive matings, limiting the spread of UPI. Critically, while this process favours some degree of UPI, it neither leads to the establishment of linked mating types nor the collapse of multiple mating types to two. Only when two mating types exist beforehand can associated UPI mutants spread to fixation under the pressure of high mitochondrial mutation rate, large mitochondrial population size and selfish mutants. Variation in these parameters could account for the range of UPI actually observed in nature, from strict UPI in some Chlamydomonas species to BPI in yeast. We conclude that UPI of mitochondria alone is unlikely to have driven the evolution of two mating types in unicellular eukaryotes.

scholarly journals Tropical tree diversity enhances light capture through crown plasticity and spatial and temporal niche differences

Ecology ◽  
2014 ◽  
Vol 95 (9) ◽  
pp. 2479-2492 ◽  
Author(s):  
Jurgis Sapijanskas ◽  
Alain Paquette ◽  
Catherine Potvin ◽  
Norbert Kunert ◽  
Michel Loreau
Keyword(s):  
Tree Diversity ◽  
Tropical Tree ◽  
Temporal Niche ◽  
Crown Plasticity ◽  
Niche Differences ◽  
Light Capture

scholarly journals Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration

2020 ◽  
Author(s):  
Swetha Mohan ◽  
Paul J. Sampognaro ◽  
Andrea R. Argouarch ◽  
Jason C. Maynard ◽  
Anand Patwardhan ◽  
...  
Keyword(s):  
Frontotemporal Lobar Degeneration ◽  
Cathepsin L ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Specific Manner ◽  
Lysosomal Proteases ◽  
Ph Dependent ◽  
Increased Activity

Abstract Background - Progranulin loss-of-function mutations are linked to frontotemporal lobar degeneration with TDP-43 positive inclusions (FTLD-TDP-Pgrn). Progranulin (PGRN) is an intracellular and secreted pro-protein that is proteolytically cleaved into individual granulin peptides, which are increasingly thought to contribute to FTLD-TDP-Pgrn disease pathophysiology. Intracellular PGRN is processed into granulins in the endo-lysosomal compartments. Therefore, to better understand the conversion of intracellular PGRN into granulins, we systematically tested the ability of different classes of endo-lysosomal proteases to process PGRN at a range of pH setpoints. Results - In vitro cleavage assays identified multiple enzymes that can process human PGRN into multi- and single-granulin fragments in a pH-dependent manner. We confirmed the role of cathepsin B and cathepsin L in PGRN processing and showed that these and several previously unidentified lysosomal proteases (cathepsins E, G, K, S and V) are able to process PGRN in distinctive, pH-dependent manners. In addition, we have demonstrated a new role for asparagine endopeptidase (AEP) in processing PGRN, with AEP having the unique ability to liberate granulin F from the pro-protein. Brain tissue from individuals with FTLD-TDP-Pgrn show increased PGRN processing to granulin F and an increased activity of AEP, in a region-specific manner. Conclusions - This study demonstrates that multiple lysosomal proteases may work in concert to liberate multi-granulin fragments and granulins. It also implicates both AEP and granulin F in the neurobiology of FTLD-TDP-Pgrn. Modulating progranulin cleavage and granulin production may represent therapeutic strategies for FTLD-Pgrn and other progranulin-related diseases.

scholarly journals Tropical tree diversity mediates foraging and predatory effects of insectivorous birds

2018 ◽  
Vol 285 (1890) ◽  
pp. 20181842 ◽  
Author(s):  
Colleen S. Nell ◽  
Luis Abdala-Roberts ◽  
Victor Parra-Tabla ◽  
Kailen A. Mooney
Keyword(s):  
Species Richness ◽  
Indirect Effect ◽  
Tree Species ◽  
Attack Rate ◽  
Tree Diversity ◽  
Trophic Levels ◽  
Tropical Tree ◽  
Insectivorous Birds ◽  
Bird Abundance ◽  
Tree Species Richness

Biodiversity affects the structure of ecological communities, but little is known about the interactive effects of diversity across multiple trophic levels. We used a large-scale forest diversity experiment to investigate the effects of tropical tree species richness on insectivorous birds, and the subsequent indirect effect on predation rates by birds. Diverse plots (four tree species) had higher bird abundance (61%), phylogenetic diversity (61%), and functional diversity (55%) than predicted based on single-species monocultures, which corresponded to higher attack rates on artificial caterpillars (65%). Tree diversity effects on attack rate were driven by complementarity among tree species, with increases in attack rate observed on all tree species in polycultures. Attack rates on artificial caterpillars were higher in plots with higher bird abundance and diversity, but the indirect effect of tree species richness was mediated by bird diversity, providing evidence that diversity can interact across trophic levels with consequences tied to ecosystem services and function.

scholarly journals A Tissue-Specific Coactivator of Steroid Receptors, Identified in a Functional Genetic Screen

2000 ◽  
Vol 20 (7) ◽  
pp. 2411-2422 ◽  
Author(s):  
Darko Knutti ◽  
Adesh Kaul ◽  
Anastasia Kralli
Keyword(s):  
Transcriptional Activation ◽  
Mammalian Cells ◽  
Steroid Receptors ◽  
Activation Function ◽  
Regulatory Function ◽  
Dependent Manner ◽  
Ligand Effect ◽  
Dimerization Domain ◽  
Tissue Specific ◽  
Specific Manner

ABSTRACT Steroid receptors mediate responses to lipophilic hormones in a tissue- and ligand-specific manner. To identify nonreceptor proteins that confer specificity or regulate steroid signaling, we screened a human cDNA library in a steroid-responsive yeast strain. One of the identified cDNAs, isolated in the screen as ligand effect modulator 6, showed no homology to yeast or Caenorhabditis elegansproteins but high similarity to the recently described mouse coactivator PGC-1 and was accordingly termed hPGC-1. The hPGC-1 DNA encodes a nuclear protein that is expressed in a tissue-specific manner and carries novel motifs for transcriptional regulators. The expression of hPGC-1 in mammalian cells enhanced potently the transcriptional response to several steroids in a receptor-specific manner. hPGC-1-mediated enhancement required the receptor hormone-binding domain and was dependent on agonist ligands. Functional analysis of hPGC-1 revealed two domains that interact with steroid receptors in a hormone-dependent manner, a potent transcriptional activation function, and a putative dimerization domain. Our findings suggest a regulatory function for hPGC-1 as a tissue-specific coactivator for a subset of nuclear receptors.

Sign in / Sign up

Export Citation Format

Share Document