Linking Stress,Catecholamine Autotoxicity,and Allostatic Load with Neurodegenerative Diseases: A Focused Review in Memory of Richard Kvetnansky

In this Focused Review, we provide an update about evolving concepts that may link chronic stress and catecholamine autotoxicity with neurodegenerative diseases such as Parkinson’s disease. Richard Kvetnansky’s contributions to the field of stress and catecholamine systems inspired some of the ideas presented here. We propose that coordination of catecholaminergic systems mediates adjustments maintaining health and that senescence-related disintegration of these systems leads to disorders of regulation and to neurodegenerative diseases such as Parkinson’s disease. Chronically repeated episodes of stress-related catecholamine release and reuptake, with attendant increases in formation of the toxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde, might accelerate this process.     

Distribution of fishes in the Río Guayalejo-Río Tamesí system and relationships with environmental factors in northeastern Mexico

A priority issue in ecology and biogeography is understanding the patterns in species diversity and the causal factors of their distribution, which allows the generation of information for conservation strategies. The longitudinal distribution of fishes and their relationships with environmental variables were studied in the Guayalejo-Río Tamesí system (northeastern Mexico) from February 2000 to July 2001. A total of 5918 fish were caught in 27 collections along an altitudinal gradient in the main river course, from high mountain (1500 masl) to coastal plain near Tampico. Forty-three native and five exotic species, belonging to 35 genera in 23 families, were identified. Cluster analyses identified four major fish habitats in the river system. A distinctive euryhaline marine fish habitat (1) occurs near the mouth with native and two exotic species. Two other habitats consist essentially of freshwater fish species that are distributed along the longitudinal gradient. One of these habitats (habitat 4) shows greater diversity, as per the Shannon index value, and also includes amphidromous fish, in addition to two exotic freshwater fish; the other (habitat 2) includes freshwater, euryhaline and three exotic species. The changes in the frequency of occurrence and the abundance of Gambusia vittata, Astyanax mexicanus, and Xiphophorus variatus contribute to explaining differences between these habitats. Another habitat (3) is represented by two sampling sites located near the mouth and consist of freshwater and euryhaline fish and three exotic cyprinids with broad salinity tolerance. The low abundance and richness of exotic species suggest little impact on native fish fauna in this river. The fish assemblage of the Guayalejo-Tamesí river system species changes along a longitudinal gradient with the addition, replacement and presence of indicator species. Upstream fish fauna is mostly composed of freshwater species, some of them generalists that inhabit the entire longitudinal gradient, others that are restricted to certain sites, and the remainder of species is an assemblage composed of a mixture of euryhaline freshwater and marine species near the mouth.     

Disturbance-driven changes in fish assemblages caused by a sudden increase in salinity in a perennial desert stream

Disturbance is a key factor in structuring fish assemblages in rivers; characterizing reactions to disturbance is especially important in systems containing endangered species due to their vulnerability to extinction. A natural disturbance event occurred in the Virgin River in 1985, when normal flow patterns changed due to the appearance of a sinkhole upstream of the hot saline Pah Tempe Springs. This led to abnormally elevated levels of temperature and salinity that propagated downstream. We examined changes in fish assemblages at five sites in a 21 km reach downstream from the hot springs in the mainstem Virgin River, which were monitored monthly (with the exception of 1 site monitored biannually) between 1984 and 1987. Specifically, we compared the responses of the different fish species in space and time. Of the six native species investigated, speckled dace, spinedace, and the endangered woundfin experienced declines in abundance at sites closest to the disturbance. In contrast, Virgin River chub, another endangered species, experienced increases in abundance in sites nearest the disturbance, and desert sucker and flannelmouth sucker showed no change. Redundancy analysis confirmed that changes in assemblage structure were significant. Differential responses to the disturbance appeared to correlate with differences in feeding ecology, with insectivores being the most affected group. In terms of recovery, species with higher abundances in neighboring sites experienced faster recoveries than those with lower abundances. This study characterizes disturbance reactions in the Virgin River, and emphasizes the susceptibility of rare species to natural disturbances and subsequent depression of recolonization rates.     

De novo assembly of mitochondrial genomes provides insights into genetic diversity and molecular evolution in wild boars and domestic pigs

Up to date, the scarcity of publicly available complete mitochondrial sequences for European wild pigs hampers deeper understanding about the genetic changes following domestication. Here, we have assembled 26 de novo mtDNA sequences of European wild boars from next generation sequencing (NGS) data and downloaded 174 complete mtDNA sequences to assess the genetic relationship, nucleotide diversity, and selection. The Bayesian consensus tree reveals the clear divergence between the European and Asian clade and a very small portion (10 out of 200 samples) of maternal introgression. The overall nucleotides diversities of the mtDNA sequences have been reduced following domestication. Interestingly, the selection efficiencies in both European and Asian domestic pigs are reduced, probably caused by changes in both selection constraints and maternal population size following domestication. This study suggests that de novo assembled mitogenomes can be a great boon to uncover the genetic turnover following domestication. Further investigation is warranted to include more samples from the ever-increasing amounts of NGS data to help us to better understand the process of domestication.     

Effect of cultivation years on saponins in <Emphasis Type="Italic">Paris Polyphylla</Emphasis> var. <Emphasis Type="Italic">yunnanensis</Emphasis> using ultra-high liquid chromatography–tandem mass spectrometry and Fourier transform infrared spectroscopy

Paris Polyphylla var. yunnanensis (PPY) has been used in traditional medicine for the treatment of parotitis and abscess. Previous studies showed the quality of PPY was associated with cultivation years. In this study, we applied ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) and Fourier transform infrared (FT-IR) spectroscopy to measure the variation of saponins due to cultivation years in cultivated PPY. A rapid UHPLC–MS/MS method was developed for simultaneous determination of six major steroidal saponins (polyphyllin I, II, V, VI, VII and gracillin). Principal component analysis (PCA) was selected for pattern recognition of FT-IR profiles. The concentration of six targeted steroid saponins varied with the increase of cultivation year and attained the maximum level at 8th year (22.65?±?1.65 mg g^?1). A dynamic change with the growth of PPY presented in the content of diosgenin-type saponins and pennogenin-type saponins. After the treatment of standard normal variate (SNV), the PCA result showed that 4th and 5th years’ samples were solely classified into two parts and the chemical information of other samples was quite similar. According to FT-IR and UPLC-MS/MS results, an optimal harvest time recommend at 7th or 8th year in the current stage. These results could support the previous view that the variations of metabolites were associated with cultivation years and provided chemical evidence for further research on the agricultural practice of PPY.     

Structure of ground-dwelling arthropod assemblages in vegetation units of Área Natural Protegida Península Valdés,Patagonia, Argentina

Knowing the spatial variation of insect and arachnid assemblages and their relationship with habitat variables is critical to understand the structure and dynamics of these communities in arid environments. The aim of this paper was to analyze the variation in ground-dwelling arthropod assemblages across three representative vegetation units of the Área Natural Protegida Península Valdés (Patagonia, Argentina). We asked whether environmental differences among representative vegetation units were associated to distinct arthropod assemblages. We selected three plant communities: grass, dwarf-shrub, and shrub steppes, and established three sampling sites within each of them. We measured variables of vegetation structure and soil characteristics and collected the arthropods using 10 pitfall traps per site. We analyzed the structure of arthropod assemblages at both family and ant species taxonomic levels. Each plant community displayed a distinctive assemblage, with differences in diversity, taxa abundance, trophic structure and functional groups of ants. Vegetation variables explained a higher proportion of the variation in the structure of the ground-dwelling arthropod assemblages than the soil variables. This work highlights the importance of the different vegetation units for the conservation of ground-dwelling arthropod biodiversity in Península Valdés.     

TROSY pulse sequence for simultaneous measurement of the <Superscript>15</Superscript>N <Emphasis Type="Italic">R</Emphasis><Subscript>1</Subscript> and {<Superscript>1</Superscript>H}–<Superscript>15</Superscript>N NOE in deuterated proteins

A TROSY-based NMR experiment is described for simultaneous measurement of the ¹⁵N longitudinal relaxation rate constant R₁ and the {¹H}–¹⁵N nuclear Overhauser enhancement. The experiment is based on the observation that the TROSY mixing pulse sequence element symmetrically exchanges ¹H and ¹⁵N magnetizations. The accuracy of the proposed technique is validated by comparison to independent measurements of both relaxation parameters for the protein ubiquitin. The simultaneous experiment is approximately 20–33% shorter than conventional sequential measurements.     

Substitution of Alanine at Position 184 with Glutamic Acid in <Emphasis Type="Italic">Escherichia coli</Emphasis> PBP5 Ω-Like Loop Introduces a Moderate Cephalosporinase Activity

Escherichia coli PBP5, a DD-carboxypeptidase (DD-CPase), helps in maintaining cell shape and intrinsic β-lactam resistance. Though PBP5 does not have β-lactamase activity under physiological pH, it has a common but shorter Ω-like loop resembling class A β-lactamases. However, such Ω-like loop lacks the key glutamic acid residue that is present in β-lactamases. It is speculated that β-lactamases and DD-CPases might have undergone divergent evolution leading to distinct enzymes with different substrate specificities and functions indicating the versatility of the Ω-loops. Nonetheless, direct experimental evidence favoring the idea is insufficient. Here, aiming to investigate the effect of introducing a glutamic acid residue in the PBP5 Ω-like loop, we substituted A184 to E to create PBP5_A184E. Expression of PBP5_A184E in E. coli ?PBP5 mutant elevates the β-lactam resistance, especially for cephalosporins. However, like PBP5, PBP5_A184E has the ability to complement the aberrantly shaped E. coli septuple PBP mutant indicating an unaffected in vivo DD-CPase activity. Biochemical and bioinformatics analyses have substantiated the dual enzyme nature of the mutated enzyme possessing both DD-CPase and β-lactamase activities. Therefore, substitution of A184 to E of Ω-like loop alone can introduce the cephalosporinase activity in E. coli PBP5 supporting the phenomenon of a single amino acid polymorphism.     

Expression and Functional Characterization of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Recombinant <Emphasis Type="SmallCaps">l</Emphasis>.Asparaginase

Recombinant _l.asparaginase, L.ASNase, from Pseudomonas aeruginosa was purified using nickel affinity chromatography. The affinity purified L.ASNase exhibited a protein band with a molecular weight of 72.4 kDa on a native polyacrylamide gel and 36.276 kDa using SDS–PAGE. The activity of the purified L.ASNase was enhanced by Mg²⁺ and inhibited by Zn²⁺ at a concentration of 5 mM. The specificity of the recombinant L.ASNase towards different substrates was examined, and it was found that the enzyme showed the highest activity towards l.asparagine. Moreover, the enzyme showed lower activity towards other substrates such as _L.glutamine, urea and acrylamide. The in vitro hemolysis assay revealed that the purified L.ASNase did not show hemolysis effect on blood erythrocytes. Serum and trypsin half-life of L.ASNase suggested that the recombinant L.ASNase retained 50% of its initial activity after 90 and 60 min incubation period in serum and trypsin separately.