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Topic Review
β-N-Methylamino-L-Alanine Producers and Biosynthesis Pathways
Non-proteinogenic amino acid β-N-methylamino-L-alanine (BMAA) (syn: α-amino-β-methylaminopropionic acid, MeDAP; and 3-N-methyl-2,3-diaminopropanoic acid) was first isolated from the seeds of Cycas micronesica K.D.Hill (Cycadaceae). Non-proteinogenic amino acids (NPAAs) are not naturally encoded genetically and are not contained in the genetic code of any organism; however, they play diverse roles in prokaryotic and eukaryotic organisms. The research interest in BMAA arose due to the discovery of a link between chronic exposure to this diaminoacid and the occurrence of neurodegenerative diseases.
  • 553
  • 19 Aug 2022
Topic Review
Soil Microorganisms on Plant Performance
The spatially heterogeneous distribution of soil nutrients is ubiquitous in terrestrial ecosystems and has been shown to promote the performance of plant communities, influence species coexistence, and alter ecosystem nutrient dynamics. Plants interact with diverse soil microbial communities that lead to an interdependent relationship (e.g., symbioses), driving plant community productivity, belowground biodiversity, and soil functioning.
  • 550
  • 11 Jan 2023
Topic Review
Nematode Communities and Soil Health under Climate Change
Soil health is intimately intertwined with ecosystem services. Climate change negatively impacts ecosystem functioning, by altering carbon and nitrogen biogeochemical cycles and shifting nutrient bioavailability, thus hampering food production and exacerbating biodiversity loss. Soil ecosystem services are provided by belowground biota, and as the most abundant metazoans on Earth, nematodes are key elements of soil food webs and reliable bioindicators of soil health. 
  • 543
  • 01 Aug 2023
Topic Review
Restoring Mexican Tropical Dry Forests
Deforestation is the dominant threat to tropical dry forests (TDFs) in Mexico. Its causes include agriculture, tourism, and mining. In some cases, unassisted forest regeneration is sufficient to return diverse forest cover to a site, but in other cases, changes in land use are so severe that active restoration is required to reintroduce tree cover. 
  • 534
  • 15 Apr 2022
Topic Review
Intraspecific Heterogeneity
Intraspecific heterogeneity describes the phenotypic and genetic diversity within the population of a species. Intraspecific heterogeneity is derived from microevolution and is a strong driving force for the expansion of invasive species such as the bloom-forming cyanobacterium Raphidiopsis raciborskii.
  • 525
  • 30 Jan 2023
Topic Review
Corvids in Urban Environments
With regard to their high adaptability to human settlements and global distribution, corvid birds (crows, ravens, jays, etc.) are good models to understand the impacts of urbanization on wildlife. At least 30 corvid species have become successfully accustomed or adapted to urbanized environments. The availability of easily accessible food and artificial nesting sites, coupled with low levels of predation, were found as the most important factors benefitting corvids in cities around the world. 
  • 512
  • 13 Dec 2021
Topic Review
Contaminants of Soil–Vegetable Interface
Vegetable consumption is considered as an important part of the human diet as it serves as an essential source of vitamins, nutrients, and minerals. In this regard, the demand for new technologies and ideas in the agricultural sector has grown steadily to help expand the production of vegetable crops. The uptake and accumulation of trace elements (TEs) and pharmaceuticals and personal care products (PPCPs) as contaminants in vegetables have been accelerated by man-made activities.
  • 506
  • 22 Nov 2022
Topic Review
Thermal Effects on Ecological Traits of Salmonids
A thermal window bounded by the upper and lower incipient lethal temperatures (UILT and LILT) determines where salmonids can survive. For most salmonids, LILT is close to 0 and UILT is between 20 and 30 °C. UILT and LILT are influenced by the acclimation temperature. Thermal tolerance is affected by fish size and ambient oxygen content, which decreases with increasing temperature.
  • 505
  • 30 Jun 2023
Topic Review
Pheromones Secreted by Nematodes
Pheromones are chemical signals secreted by one individual that can affect the behaviors of other individuals within the same species. Ascaroside is an evolutionarily conserved family of nematode pheromones that play an integral role in the development, lifespan, propagation, and stress response of nematodes. Their general structure comprises the dideoxysugar ascarylose and fatty-acid-like side chains. Ascarosides can vary structurally and functionally according to the lengths of their side chains and how they are derivatized with different moieties.  Ascarosides (ASCRs) represent the majority of the pheromones secreted by nematodes. The molecular formula for an ascaroside, C33H68O4, was first proposed by Schulz and Becker in 1933. Different phenotypes of nematode species are produced by different ascarosides or combinations of ascarosides; even slight changes in the chemical structure tend to produce drastically different patterns of activity. As a rule, the patterns of the biosynthesis of ascarosides are linked to the phylogeny, lifestyle, and ecological niche of the organism. In addition, different concentrations of the same ascarosides can have different effects on nematodes. Other chemicals such as vanillic acid function as pheromones in some nematodes, but there have been comparatively few studies and discoveries in this area.
  • 503
  • 27 Jun 2023
Topic Review
Plague and Trace Metals in Natural Systems
All pathogenic organisms are exposed to abiotic influences such as the microclimates and chemical constituents of their environments. Even those pathogens that exist primarily within their hosts or vectors can be influenced directly or indirectly. Yersinia pestis, the flea-borne bacterium causing plague, is influenced by climate and its survival in soil suggests a potentially strong influence of soil chemistry. 
  • 500
  • 26 Aug 2022
Topic Review
Impact of Climate Change on Soil N2O Emission
Microbial-driven processes, including nitrification and denitrification closely related to soil nitrous oxide (N2O) production, are orchestrated by a network of enzymes and genes such as amoA genes from ammonia-oxidizing bacteria (AOB) and archaea (AOA), narG (nitrate reductase), nirS and nirK (nitrite reductase), and nosZ (N2O reductase). However, how climatic factors could influence these genes and processes and, consequently, soil N2O emissions remain unclear. 
  • 499
  • 26 Feb 2024
Topic Review
Multitrophic Interactions of Entomopathogenic Fungi, Crops, and Insects
Multitrophic interactions link several trophic levels, including plants, phytophagous, predators, parasitoids, and/or pathogens.
  • 496
  • 21 Feb 2023
Topic Review
Vertebrate Hindbrain Segmentation
In metazoans, Hox genes are key drivers of morphogenesis. In chordates, they play important roles in patterning the antero-posterior (A-P) axis. A crucial aspect of their role in axial patterning is their collinear expression, a process thought to be linked to their response to major signaling pathways such as retinoic acid (RA) signaling. The amplification of Hox genes following major events of genome evolution can contribute to morphological diversity. In vertebrates, RA acts as a key regulator of the gene regulatory network (GRN) underlying hindbrain segmentation, which includes Hox genes. 
  • 494
  • 18 Jan 2022
Topic Review
Differential Spatiotemporal Distribution of Cryptic Intertidal Bangiales
Morphologically similar but genetically distinct species have been termed cryptic and most have been assumed to be ecologically similar. However, if these species co-occur at a certain spatial scale, some niche differences at finer scales should be expected to allow for coexistence. Bladed Bangiales were identified and quantified across four intertidal elevations and four seasons for one year, at five rocky intertidal sites (between 39° S and 43° S) in southern Chile. Species determination was based on partial sequences of the mitochondrial cytochrome c oxidase 1 (COI) gene amplification. To assess species gross morphology, thallus shape, color, and maximum length and width were recorded. Hundreds of organisms were classified into nine Bangiales species belonging to three genera (i.e., Fuscifolium, Porphyra, and Pyropia), including five frequent (>97% of specimens) and four infrequent species. All species, except for Pyropia saldanhae, had been previously reported along the coasts of Chile. The thallus shape and color were very variable, and a large overlap of the maximum width and length supported the cryptic status of these species. Multivariate analyses showed that the main variable affecting species composition was intertidal elevation. Species such as Py. orbicularis were more abundant in low and mid intertidal zones, while others, such as Po. mumfordii and Po. sp. FIH, were principally observed in high and spray elevations. Despite all numerically dominant species being present all year long, a slight effect of seasonal variation on species composition was also detected. These results strongly support the existence of spatial niche partitioning in cryptic Bangiales along the Chilean rocky intertidal zone.
  • 493
  • 10 Mar 2022
Topic Review
Rare Earth Elements (REE)
The rare earth elements (REE) comprise a group of 16 chemically very similar elements that occur widespread in rocks, soils, and water bodies, share similar ionic radii to the essential element Ca2+, and consequently also occur in biota. Given that REE form mainly trivalent cations, they also share similarities to Al3+. Compared to their chemical cognate Ca, they have a higher reactivity. Thus, their accumulation in soils may constitute a severe environmental threat. Over the last decades, the increasing use of REE in modern technology and fertilizers raised concerns about the pollution of soils and water bodies, which led to a rapidly increasing number of publications dealing with REE toxicity to plants, animals and humans, the fate of REE in soil–plant systems, REE cycling in ecosystems and impacts of REE pollution on food security.
  • 488
  • 05 Feb 2024
Topic Review
Soil Bacterium Bacillus thuringiensis
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of the findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. 
  • 482
  • 19 May 2023
Topic Review
Tawny Owl and Urbanization Structure
Tawny owl (Strix aluco) is a ubiquitous and resilient raptor that successfully exploits heterogeneous patchy habitats. Due to its abundance and broad geographic range, it is an appropriate bird species model with which to test how raptors colonize urban environments and which drivers from these urban habitats play a role in explaining the occurrence of these species. It is necessary to understand how urbanization affects the tawny owl at the landscape scale. The effect of habitat fragmentation (i.e., forest fragmentation) on tawny owl populations has been studied previously ; however, to our knowledge, the effect of urban habitat fragmentation remains unknown. In addition, it is not common to study habitat selection through a multiscale approach, even though different variables can be important to a species at different spatial scales. As such, studies conducted at arbitrarily defined scales may suffer from serious limitations .
  • 467
  • 29 Oct 2021
Topic Review
Ecological Infrastructures May Enhance Lepidopterans Predation
Ecological infrastructures (EIs) are considered relevant components in agricultural landscapes to support biodiversity and ecosystem services. The EI typologies influenced differently the predator groups and the overall predation rate. Major differences were observed for bird predation, being higher in woody EIs. A positive correlation between predation rate and EIs area of the surrounding landscape, as well as a negative correlation with the distance to the nearest riparian and woody EIs, was observed for birds. The observed dissimilarities in the predators’ response may be related to habitat differences and its functional connectivity. The overall monthly low predation rates are possibly related to the intensive agricultural system and the small area occupied by EIs.
  • 467
  • 31 Mar 2022
Topic Review
Applying Pickering Emulsions to Food
The proper mix of nanocellulose to a dispersion of polar and nonpolar liquids creates emulsions stabilized by finely divided solids (instead of tensoactive chemicals) named Pickering emulsions. These mixtures can be engineered to develop new food products with innovative functions, potentially more eco-friendly characteristics, and reduced risks to consumers. Although cellulose-based Pickering emulsion preparation is an exciting approach to creating new food products, there are many legal, technical, environmental, and economic gaps to be filled through research.
  • 457
  • 12 Oct 2023
Topic Review
Plant-Microbe Interactions in Flood Conditions
The impact of flooding as an adverse environmental factor is outlined. It has been shown that plants and bacteria under flooding conditions primarily suffer from a lack of oxygen and activation of anaerobic microflora. The combined effects of heavy metals and flooding on microorganisms and plants are also discussed.
  • 449
  • 16 May 2023
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