Prion Strain Differences in Accumulation of PrPSc on Neurons and Glia Are Associated with Similar Expression Profiles of Neuroinflammatory Genes: Comparison of Three Prion Strains

Misfolding and aggregation of host proteins are important features of the pathogenesis of neurodegenerative diseases including Alzheimer’s disease, Parkinson’s disease, frontotemporal dementia and prion diseases. In all these diseases, the misfolded protein increases in amount by a mechanism involving seeded polymerization. In prion diseases, host prion protein is misfolded to form a pathogenic protease-resistant form, PrPSc, which accumulates in neurons, astroglia and microglia in the CNS. Here using dual-staining immunohistochemistry, we compared the cell specificity of PrPSc accumulation at early preclinical times post-infection using three mouse scrapie strains that differ in brain regional pathology. PrPSc from each strain had a different pattern of cell specificity. Strain 22L was mainly associated with astroglia, whereas strain ME7 was mainly associated with neurons and neuropil. In thalamus and cortex, strain RML was similar to 22L, but in substantia nigra, RML was similar to ME7. Expression of 90 genes involved in neuroinflammation was studied quantitatively using mRNA from thalamus at preclinical times. Surprisingly, despite the cellular differences in PrPSc accumulation, the pattern of upregulated genes was similar for all three strains, and the small differences observed correlated with variations in the early disease tempo. Gene upregulation correlated with activation of both astroglia and microglia detected in early disease prior to vacuolar pathology or clinical signs. Interestingly, the profile of upregulated genes in scrapie differed markedly from that seen in two acute viral CNS diseases (LaCrosse virus and BE polytropic Friend retrovirus) that had reactive gliosis at levels similar to our prion-infected mice.     

First Report of Peronospora belbahrii on Sweet Basil in Baja California Sur,México

In Baja California Sur, Mexico, a foliar disease occurred on sweet basil which seriously affected its quality and yield. The most common symptoms were yellowing and necrosis on leaves, caused by a downy mycelium growth on the lower leaf surface. Symptomatic leaves from two sampling sites were collected for morphological studies and molecular analysis of pathogen DNA. Based on morphological characteristics (sporangiophore size of 240–530 × 7–11 μm, branches of 5–8 order and a sporangia size of 27–31 × 21–25 μm) and molecular analysis (the GenBank blast of the PCR assays showed unique rDNA sequence data with 99% similarity to P. belbahrii), the pathogen was identified as Peronospora belbahrii, the causal agent of basil downy mildew. This is the first report of P. belbahrii affecting sweet basil in Mexico.     

Biosynthesis and bioactivity of Cynara cardunculus L. guaianolides and hydroxycinnamic acids: a genomic,biochemical and health-promoting perspective

Phytochemistry Reviews - Cynara cardunculus health benefits have aroused much interest, leading to the discovery of valuable bioactive compounds with a crucial role in plant defence. Guaianolides...     

Fractionation of Heavy Metals in Mine Tailings Amended with Composted Manure

This study evaluated the effect of composted cow manure (CCM) on the chemical fractionation and retention degree of heavy metals (HMs) in mine tailings from Zimapán, México. In a greenhouse experiment, mine tailings from three deposits were incubated for 3 months; experimental units were placed in a PVC container, where increasing doses of CCM were applied. HM pseudo-total concentrations, HM extractions with ethylenediaminetetraacetic acid (EDTA, 0.05 M), and a sequential chemical extraction (SCE) were carried out. The HM concentrations were determined by atomic absorption spectrophotometry. The pseudo-total concentrations of Pb, Cu, Cd, and Ni found were up to 1506, 206, 27, and 23 mg kg^?1, respectively; extractable Pb was up to 42%; 21% for Cu; 51% for Cd; and 16% of Ni of the pseudo-total concentrations of each metal. Treatment with 12% of CCM in mine tailing decreased EDTA-extractable HM concentrations, while the SCE revealed a decrease in exchangeable fraction and an increase in the organic fraction of HM. A positive correlation between CCM application and organic fractions of HMs was found, although the highest increasements were recorded in the organic fraction.     

Diversity and trophic structure of insects associated with grains of three maize landraces in San Agustín Loxicha,Oaxaca, Mexico

Diversity and trophic structure of grain insect communities were examined in Olotillo, Nal‐Tel and Comiteco maize landraces cultivated within a milpa agroecosystem by Zapotec ethnic groups in Mexico. Higher insect diversity was expected in Olotillo, whose cultivation comprises a wide variety of agroecosystems, and low insect abundance in Nal‐Tel with small grains and thick testa. Forty Olotillo cobs were collected at low, medium and high elevations, and 40 each of Nal‐Tel at low elevation and Comiteco at high elevation. Cobs were monitored for 30 days under controlled laboratory conditions until all insects emerged. Thickness of testa of 400 grains from each landrace was measured. Community composition and trophic structure were described and standard diversity indices were estimated. A total of 9,708 insects, corresponding to five orders, 24 families and 36 species, were recorded, with six species not previously reported in this region. Insect guilds were composed of 70% phytophages, 22% parasitoids and 8% predators. Species richness was S = 27, 16 and 8 in Olotillo, Comiteco and Nal‐Tel, respectively. Nal‐Tel and Olotillo had the highest diversity index values (H′ = 1.32 and 1.2, respectively) and no significant differences; Comiteco had the lowest value (H′ = 0.65) and differed significantly from the other landraces. Comiteco and Olotillo, which have large grains and thin testa, showed higher insect abundance than Nal‐Tel, which has small grains and thick testa and showed lower abundance. Results support our hypotheses and highlight the role of traditional crop management in insect agrobiodiversity maintenance and conservation.     

Melanin processing by keratinocytes: A non‐microbial type of host‐pathogen interaction?

The mechanisms that regulate skin pigmentation have been the subject of intense research in recent decades. In contrast with melanin biogenesis and transport within melanocytes, little is known about how melanin is transferred and processed within keratinocytes. Several models have been proposed for how melanin is transferred, with strong evidence supporting coupled exo/endocytosis. Recently, two reports suggest that upon internalization, melanin is stored within keratinocytes in an arrested compartment, allowing the pigment to persist for long periods. In this commentary, we identify a striking parallelism between melanin processing within keratinocytes and the host‐pathogen interaction with Plasmodium, opening new avenues to understand the complex molecular mechanisms that ensure skin pigmentation and photoprotection.      

Bare soil cover and arbuscular mycorrhizal community in the first montane forest restoration in Central Argentina

Soil erosion affects extensive areas worldwide and must be urgently reduced promoting plant cover and beneficial microorganisms associated with plants, including arbuscular mycorrhizal fungi (AMF). In mountain environments, plant cover is difficult to enhance due to harsh conditions during the dry season and steep slopes. Our objective was to evaluate the percentage of the soil surface covered by plants and the AMF community associated with trees 12.5 years after planting during forest restoration efforts in microsites at different levels of soil degradation. The study was performed in the first montane forest restoration initiative of Central Argentina, where one of the trials consisted of planting Polylepis australis saplings at microsites with different levels of soil degradation: high, intermediate, and low. After 12.5 years, percentage of bare soil cover was significantly reduced by 36 and 37% in the high and intermediate degradation microsites, respectively. Low degradation microsites were initially very low in bare soil and did not significantly change. Mycorrhizal colonization, hyphae, vesicles, arbuscules, AMF diversity, and community structure were similar among microsite types. Percentage of hyphal entry points was higher at microsites with low degradation, number of spores was higher in high and intermediate degradation, and species richness was higher in high degradation. Acaulospora and Glomus were the most abundant genera in all microsites. We conclude that even in the most degraded microsites around 2.8% of the bare soil is covered by vegetation each year and that the arbuscular mycorrhizal community is highly tolerant and adapted to soils with different disturbance types.     

The rate of environmental fluctuations shapes ecological dynamics in a two‐species microbial system

Species interactions change when the external conditions change. How these changes affect microbial community properties is an open question. We address this question using a two‐species consortium in which species interactions change from exploitation to competition depending on the carbon source provided. We built a mathematical model and calibrated it using single‐species growth measurements. This model predicted that low frequencies of change between carbon sources lead to species loss, while intermediate and high frequencies of change maintained both species. We experimentally confirmed these predictions by growing co‐cultures in fluctuating environments. These findings complement more established concepts of a diversity peak at intermediate disturbance frequencies. They also provide a mechanistic understanding for how the dynamics at the community level emerges from single‐species behaviours and interspecific interactions. Our findings suggest that changes in species interactions can profoundly impact the ecological dynamics and properties of microbial systems.