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Background: Desipramine a representative of tricyclic antidepressants (TCAs) promotes recovery of depressed patients by inhibition of reuptake of neurotransmitters serotonin (SER) and norepinephrine (NE) in the presynaptic membrane by directly blocking their respective transporters SERT and NET. Aims: To study the effect of desipramine on programmed erythrocyte death (eryptosis) and explore the underlying mechanisms. Methods: Phosphatidylserine (PS) exposure on the cell surface as marker of cell death was estimated from annexin-V-binding, cell volume from forward scatter in flow cytometry. Hemolysis was determined photometrically, and intracellular glutathione [GSH]i from high performance liquid chromatography. Results: Desipramine dose-dependently significantly enhanced the percentage of annexin-V-binding cells and didn´t impact glutathione (GSH) synthesis. Desipramine-induced eryptosis was significantly reversed by pre-treatment of erythrocytes with either nitric oxide (NO) donor sodium nitroprusside (SNP) or N-acetyl-L-cysteine (NAC). The highest inhibitory effect was obtained by using both inhibitors together. Calcium (Ca2+) depletion aggravated desipramine-induced eryptosis. Changing the order of treatment, i.e. desipramine first followed by inhibitors, could not influence the inhibitory effect of SNP or NAC. Conclusion: Antidepressants-caused intoxication can be treated by SNP and NAC, respectively. B) Patients with chronic hypocalcemia should not be treated with tricyclic anti-depressants or their dose should be noticeably reduced. [ABSTRACT FROM AUTHOR]

Glutamate-induced excitotoxicity is a pathological basis of many acute/chronic neurodegenerative diseases. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2b) is a membrane-embedded P-type ATPase pump that manages the translocation of calcium ions (Ca2+) from cytosol into the lumen of the endoplasmic reticulum (ER) calcium stores. It participates in a wide range of biological functions in the central nervous system (CNS). However, the role of SERCA2b in glutamate-induced excitotoxicity and its mechanism must be elucidated. Herein, we demonstrate that SERCA2b mutants exacerbate the excitotoxicity of hypo-glutamate stimulation on HT22 cells. In this study, SERCA2b mutants accelerated Ca2+ depletion through loss-of-function (reduced pumping capacity) or gain-of-function (acquired leakage), resulting in ER stress. In addition, the occurrence of ER Ca2+ depletion increased mitochondria-associated membrane formation, which led to mitochondrial Ca2+ overload and dysfunction. Moreover, the enhancement of SERCA2b pumping capacity or inhibition of Ca2+ leakage attenuated Ca2+ depletion and impeded excitotoxicity in response to hypo-glutamate stimulation. In conclusion, SERCA2b mutants exacerbate ER Ca2+-depletion-mediated excitotoxicity in glutamate-sensitive HT22 cells. The mechanism of disruption is mainly related to the heterogeneity of SERCA2b mutation sites. Stabilization of SRECA2b function is a critical therapeutic approach against glutamate-induced excitotoxicity. These data will expand understanding of organelle regulatory networks and facilitate the discovery and creation of drugs against excitatory/inhibitory imbalance in the CNS. [ABSTRACT FROM AUTHOR]

Glutamate-induced excitotoxicity is a pathological basis of many acute/chronic neurodegenerative diseases. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2b) is a membrane-embedded P-type ATPase pump that manages the translocation of calcium ions (Ca2+) from cytosol into the lumen of the endoplasmic reticulum (ER) calcium stores. It participates in a wide range of biological functions in the central nervous system (CNS). However, the role of SERCA2b in glutamate-induced excitotoxicity and its mechanism must be elucidated. Herein, we demonstrate that SERCA2b mutants exacerbate the excitotoxicity of hypo-glutamate stimulation on HT22 cells. In this study, SERCA2b mutants accelerated Ca2+ depletion through loss-of-function (reduced pumping capacity) or gain-of-function (acquired leakage), resulting in ER stress. In addition, the occurrence of ER Ca2+ depletion increased mitochondria-associated membrane formation, which led to mitochondrial Ca2+ overload and dysfunction. Moreover, the enhancement of SERCA2b pumping capacity or inhibition of Ca2+ leakage attenuated Ca2+ depletion and impeded excitotoxicity in response to hypo-glutamate stimulation. In conclusion, SERCA2b mutants exacerbate ER Ca2+-depletion-mediated excitotoxicity in glutamate-sensitive HT22 cells. The mechanism of disruption is mainly related to the heterogeneity of SERCA2b mutation sites. Stabilization of SRECA2b function is a critical therapeutic approach against glutamate-induced excitotoxicity. These data will expand understanding of organelle regulatory networks and facilitate the discovery and creation of drugs against excitatory/inhibitory imbalance in the CNS.

This study evaluates the effect of three calcium levels in the diet (normal, moderate, and severe calcium depletion) on bone metabolism of male Wistar rats during their growth period. Bone mineral density (BMD) and femur length were determined in vivo during the growth stage using a single X-ray transmission system. The apparent calcium absorption was calculated in the rat adolescent and adulthood stages. At the end of the experiment, calcium concentrations in serum and urine were analyzed. The bones were evaluated postmortem to corroborate in vivo analyses. Microstructural properties of cortical and trabecular tissues of femurs bones were assessed using scanning electron microscopy. Bone mineral contents (Mg, Ca, P, and K) were quantified by inductively coupled plasma. Severe calcium depletion in the diets in the development stage affects the bone quality parameters such as bone mineral density and mineral content. Moreover, it was found thinner cortical and trabecular bone areas. Additionally, it was found that severe calcium depletion increased the apparent absorption of calcium as a defense mechanism, but with the decrease of the BMD peak, and the thickness of cortical bone as well as trabecular bone porosity. The severe calcium depletion increased the efficiency of apparent absorption calcium as a defense mechanism, but, even so, decreases the BMD peak as well as the thickness of cortical bone and trabecular bone porosity. [ABSTRACT FROM AUTHOR]

As the global burden of cancer is on the rise it is essential to develop alternate therapeutics that confer zero or minimum side effects. In this experiment, we evaluated the anticancer efficacy of graphene oxide-functionalized gold nanoparticles (GO-AuNPs) in human breast cancer cell lines MCF7 and MDA-MB-231. MTT assay revealed a dose-dependent decline in cancer cell survival. Significant alterations were detected in normal cellular morphology after treatment. Two different cell staining methods viz. acridine orange-ethidium bromide staining and annexin-cy3.18/6-carboxyfluorescein diacetate staining confirmed that the GO-AuNPs rendered their detrimental effect in cancer cells through apoptosis. To decipher the mode of apoptosis Western blotting was performed in which expression pattern of several proteins (PARP1, P53, P21, Bcl2, Bax, Caspase 9 and Caspase 3) established the intrinsic apoptosis pathway in these cell lines after GO-AuNP exposure. Intracellular calcium level, as measured by energy dispersive X-ray fluorescence analysis, was present at non-detectable level following treatment that can be linked to the cell cycle arrest and apoptotic cell death in them. Thus, GO-AuNPs were found effective in both types of human breast cancer cells viz. hormone-responsive MCF7 and chemoresistant MDA-MB-231 and can be considered as a highly potential anticancer agent in breast cancer therapy. [ABSTRACT FROM AUTHOR]

Few environmental issues have resulted in such a heated policy-science controversy in Sweden as the 1990s acidification debate in the north of the country. The belief that exceptionally high stream acidity levels during hydrological events was caused by anthropogenic deposition resulted in a governmentally funded, multi-million dollar surface-water liming program. This program was heavily criticized by a large part of the scientific community arguing that the acidity of northern streams was primarily caused by naturally occurring organic acids. Here, we revisit the acid deposition legacy in northern Sweden two decades after the culmination of the controversy by examining the long-term water chemistry trends in the Svartberget/Krycklan research catchment that became a nexus for the Swedish debate. In this reference stream, trends in acidic episodes do show a modest recovery that matches declines in acid deposition to pre-industrial levels, although stream acidity continues to be overwhelmingly driven by organic acidity. Yet there are legacies of acid deposition related to calcium losses from soils, which are more pronounced than anticipated. Finally, assessment of these trends are becoming increasingly complicated by new changes and threats to water resources that must be recognized to avoid unnecessary, expensive, and potentially counterproductive measures to adapt and mitigate human influences. Here we make the argument that while the acidification era is ending, climate change, land-use transitions, and long-range transport of other contaminants warrant close monitoring in the decades to come.

Gammarus fossarum is an often-abundant crustacean detritivore that contributes importantly to leaf litter breakdown in oligotrophic, mainly heterotrophic, headwater streams. This species requires large amounts of Ca to moult, thus allowing growth and reproduction. Because resource quality is tightly coupled to the organism’s growth and physiological status, we hypothesised that low Ca concentration [Ca] and low food resource quality (low phosphorus [P] and/or reduced highly unsaturated fatty acid [HUFA] contents) would interactively impair molecular responses (gene expression) and reproduction of G. fossarum. To investigate the effects of food resources quality, we experimentally manipulated the P content of sycamore leaves and also used diatoms because they contain high amounts of HUFAs. Three resource quality treatments were tested: low quality (LQ, unmanipulated leaves: low P content), high quality 1 (HQ1; P-manipulated leaves: high P content), and high quality 2 (unmanipulated leaves supplemented with a pellet containing diatoms: high P and HUFA content). Naturally, demineralised stream water was supplemented with CaSO4 to obtain three Ca concentrations (2, 3.5, and 10.5 mg Ca L−1). For 21 days, pairs of G. fossarum were individually exposed to one of the nine treatments (3 [Ca] × 3 resource qualities). At the individual level, strong and significant delays in moult stage were observed in gammarids exposed to lower [Ca] and to lower resource quality, with additive effects lengthening the duration of the reproductive cycle. Effects at the molecular level were investigated by measuring expression of 12 genes involved in energy production, translation, or Ca or P homeostasis. Expression of ATP synthase beta (higher in HQ2), calcified cuticle protein (higher in HQ1 and HQ2), and tropomyosin (higher in HQ2 compared to HQ1) was significantly affected by resource quality, and significant additive effects on Ca transporting ATPase expression were induced by [Ca] and resource quality (higher for low [Ca] and higher resource quality). These results highlight the potential drastic deleterious effects of water [Ca] depletion on G. fossarum physiology, populations, and ecosystem functioning, especially in oligotrophic environments. [ABSTRACT FROM AUTHOR]

Milk protein concentrate (MPC) is a high-potential source of milk proteins with significant functional, nutritional, and market appeal. Although many factors affecting MPC's techno-functional properties have been studied, an updated review is still necessary to comprehensively understand MPC's diversification potential and identify research gaps. This review highlights the crucial factors, mechanisms, and strategies to enhance MPC's techno-functional properties, including physical, enzymatic, compositional, and chemical modifications. The review targets three major components for enhancing techno-functional properties: the ionic environment (Ca depletion – colloidal & soluble Ca), casein micelles (solubilization, interaction, association, & aggregation), and powder particle makeup. The partial acidification of skim milk, retentate pH restoration and physical treatment enhance hydration properties. This review provides valuable insights for future research and development of MPC. Caption: Various physical modifications and their effect on the techno-functional properties of milk protein concentrate (MPC). [Display omitted] • Review focuses on technological interventions for improving milk protein concentrate's rehydration, emulsification, gelation, drying & applications. • Ca depletion, micelle solubilization, particles' hydrophilization, & porosity significantly enhance rehydration properties. • Partial acidification of skim milk & pH restoration of retentate show great potential for higher solubility. • Ionic environment modification of buffalo milk results in >97% solubility & >88% Ca depletion in Buffalo-MPC 60. • High hydrostatic pressure preserves lactoferrin & α-lactalbumin bioactivity in human-MPC. [ABSTRACT FROM AUTHOR]

Milk protein concentrate (MPC) powders are increasingly utilized in manufacturing of protein fortified beverages. Thermal stability of the protein dispersions is of significant importance in such applications. It is known that a decrease in pH can induce partial dissociation of casein micelles and modify the natural equilibrium of calcium and phosphate between the micelles and the serum phase. The presence of soluble casein may improve the rehydration properties of MPC powders, and may impact their thermal stability. The objective of this work was to investigate the effects of partial acidification of milk prior to ultrafiltration on the heat stability of reconstituted MPC dispersions. Milk protein concentrate powders were prepared from skim milk acidified to pH 6.0 by addition of glucono-δ-lactone, and then concentrated using ultrafiltration (UF) and diafiltration (DF). The heat stability of the reconstituted MPC dispersions was studied, by determining heat coagulation time, particle size, turbidity, viscosity, soluble and colloidal calcium and phosphate, and non-sedimentable casein both before and after heating at 120 °C. Reconstituted MPC powders made with partially acidified skim milk contained lower soluble calcium and phosphate and exhibited very poor thermal stability compared to MPC powders made with skim milk at its natural pH. The thermal stability of the acidified MPC dispersions was not only recovered by restoration of pH and the serum composition through dialysis against skim milk, but it was improved compared to control MPC dispersions. All dialyzed samples had comparable pH, protein content and calcium and phosphate concentration, but the structure of the casein micelles was altered, causing differences in the type of soluble aggregates. It was concluded that the integrity of the casein micelles and the amount of dissociated, non-sedimentable caseins play a major role in determining the thermal stability of the MPC dispersions. [ABSTRACT FROM AUTHOR]

A soil resampling approach has detected an early stage of recovery in the cation chemistry of spruce forest soil due to reductions in acid deposition. That approach is limited by the lack of soil data and archived soil samples prior to major increases in acid deposition during the latter half of the 20th century. An alternative approach is the dendrochemical analysis of dated wood to detect temporal changes in base cations back into the 19th century. To infer environmental change from dendrochemical patterns of essential base cations, internal factors that affect cation chemistry such as the maturation of sapwood and the spread of wood infection need to be recognized. Potassium concentration was a useful marker of these internal maturation and infection that could affect the concentration of essential base cations in wood. Dendrochemical patterns in samples of red spruce in the eastern United States and Norway spruce in northwestern Russia were used to determine how internal changes in base cations can be separated from external changes in root-zone soil to date major changes in the availability of essential base cations associated with a changing environment. [ABSTRACT FROM AUTHOR]

Acidic deposition caused by fossil fuel combustion has degraded aquatic and terrestrial ecosystems in North America for over four decades. The only management option other than emissions reductions for combating the effects of acidic deposition has been the application of lime to neutralize acidity after it has been deposited on the landscape. For this reason, liming has been a part of acid rain science from the beginning. However, continued declines in acidic deposition have led to partial recovery of surface water chemistry, and the start of soil recovery. Liming is therefore no longer needed to prevent further damage, so the question becomes whether liming would be useful for accelerating recovery of systems where improvement has lagged. As more is learned about recovering ecosystems, it has become clear that recovery rates vary with watershed characteristics and among ecosystem components. Lakes appear to show the strongest recovery, but recovery in streams is sluggish and recovery of soils appears to be in the early stages. The method in which lime is applied is therefore critical in achieving the goal of accelerated recovery. Application of lime to a watershed provides the advantage of increasing Ca availability and reducing or preventing mobilization of toxic Al, an outcome that is beneficial to both terrestrial and aquatic ecosystems. However, the goal should not be complete neutralization of soil acidity, which is naturally produced. Liming of naturally acidic areas such as wetlands should also be avoided to prevent damage to indigenous species that rely on an acidic environment. [ABSTRACT FROM AUTHOR]

Genetic strategies such as gene disruption and fluorescent protein tagging largely contribute to understanding the molecular mechanisms of biological functions in bacteria. However, the methods for gene replacement remain underdeveloped for the filamentous bacteria Leptothrix cholodnii SP-6. Their cell chains are encased in sheath composed of entangled nanofibrils, which may prevent the conjugation for gene transfer. Here, we describe a protocol optimized for gene disruption through gene transfer mediated by conjugation with Escherichia coli S17-1 with details on cell ratio, sheath removal, and loci validation. The obtained deletion mutants for specific genes can be used to clarify the biological functions of the proteins encoded by the target genes. Graphical overview., Competing Interests: Competing interestsThe authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2023 The Authors.)

Milk protein concentrate powders (MPC) with improved rehydration properties are often manufactured using processing steps, such as acidification and high-pressure processing, and with addition of other ingredients, such as sodium chloride, during their production. These steps are known to increase the amount of serum caseins or modify the mineral equilibrium, hence improving solubility of the retentates. The processing functionality of the micelles may be affected. The aim of this study was to investigate the effects of partial acidification by adding glucono-δ-lactone (GDL) to skim milk during membrane filtration on the structural changes of the casein micelles by observing their chymosin-induced coagulation behavior, as such coagulation is affected by both the supramolecular structure of the caseins and calcium equilibrium. Milk protein concentrates were prepared by preacidification with GDL to pH 6 using ultrafiltration (UF) and diafiltration (DF) followed by spray-drying. Reconstituted UF and DF samples (3.2% protein) treated with GDL showed significantly increased amounts of soluble calcium and nonsedimentable caseins compared with their respective controls, as measured by ion chromatography and sodium dodecyl sulfate-PAGE electrophoresis, respectively. The primary phase of chymosin-induced gelation was not significantly different between treatments as measured by the amount of caseino-macropeptide released. The rheological properties of the reconstituted MPC powders were determined immediately after addition of chymosin, both before and after dialysis against skim milk, to ensure similar serum composition for all samples. Reconstituted samples before dialysis showed no gelation (defined as tan δ = 1), and after re-equilibration only control UF and DF samples showed gelation. The gelation properties of reconstituted MPC powders were negatively affected by the presence of soluble casein, and positively affected by the amount of both soluble and insoluble calcium present after reconstitution. This work, testing the chymosin-induced gelation behavior of various reconstituted MPC samples, clearly demonstrated that a decrease in pH to 6.0 during membrane filtration affects the integrity of the casein micelles supramolecular structure with important consequences to their processing functionality. [ABSTRACT FROM AUTHOR]

An appetite for CaCl 2 and NaCl occurs in young rats after they are fed a diet lacking Ca or Na, respectively. Bilateral lesions of the parabrachial nuclei (PBN) disrupt normal taste aversion learning and essentially eliminate the expression of sodium appetite. Here we tested whether similar lesions of the PBN would disrupt the calcium-deprivation-induced appetite for CaCl 2 or NaCl. Controls and rats with PBN lesions failed to exhibit a calcium-deprivation-induced appetite for CaCl 2 . Nevertheless, both groups did exhibit a significant calcium-deprivation-induced appetite for 0.5 M NaCl. Thus, while damage to the second central gustatory relay in the PBN disrupts the appetite for 0.5 M NaCl induced by furosemide, deoxycorticosterone acetate, and polyethylene glycol, the sodium appetite induced by dietary CaCl 2 depletion remains intact. [ABSTRACT FROM AUTHOR]

Ecological evidence indicates a worldwide trend of dramatically decreased soil Ca2+ levels caused by increased acid deposition andmassive timber harvesting. Little is known about the genetic and cellularmechanismof plants' responses to Ca2+ depletion. In this study, transcriptional profiling analysis helped identify multiple extracellular Ca2+ ([Ca2+]ext) depletion-responsive genes in Arabidopsis thaliana L.,many ofwhich are involved in response to other environmental stresses. Interestingly, a group of genes encoding putative cytosolic Ca2+ ([Ca2+]cyt) sensors were significantly upregulated, implying that [Ca2+]cyt has a role in sensing [Ca2+]ext depletion. Consistent with this observation, [Ca2+]ext depletion stimulated a transient rise in [Ca2+]cyt that was negatively influenced by [K+]ext, suggesting the involvement of amembrane potential-sensitive component. The [Ca2+]cyt response to [Ca2+]ext depletion was significantly desensitized after the initial treatment, which is typical of a receptor-mediated signaling event. The response was insensitive to an animal Ca2+ sensor antagonist, but was suppressed by neomycin, an inhibitor of phospholipase C. Gd3+, an inhibitor of Ca2+ channels, suppressed the [Ca2+]ext-triggered rise in [Ca2+]cyt and downstream changes in gene expression. Taken together, this study demonstrates that [Ca2+]cyt plays an important role in the putative receptor-mediated cellular and transcriptional response to [Ca2+]ext depletion of plant cells. [ABSTRACT FROM AUTHOR]

Ecological evidence indicates a worldwide trend of dramatically decreased soil Ca2+ levels caused by increased acid deposition andmassive timber harvesting. Little is known about the genetic and cellularmechanismof plants' responses to Ca2+ depletion. In this study, transcriptional profiling analysis helped identify multiple extracellular Ca2+ ([Ca2+]ext) depletion-responsive genes in Arabidopsis thaliana L.,many ofwhich are involved in response to other environmental stresses. Interestingly, a group of genes encoding putative cytosolic Ca2+ ([Ca2+]cyt) sensors were significantly upregulated, implying that [Ca2+]cyt has a role in sensing [Ca2+]ext depletion. Consistent with this observation, [Ca2+]ext depletion stimulated a transient rise in [Ca2+]cyt that was negatively influenced by [K+]ext, suggesting the involvement of amembrane potential-sensitive component. The [Ca2+]cyt response to [Ca2+]ext depletion was significantly desensitized after the initial treatment, which is typical of a receptor-mediated signaling event. The response was insensitive to an animal Ca2+ sensor antagonist, but was suppressed by neomycin, an inhibitor of phospholipase C. Gd3+, an inhibitor of Ca2+ channels, suppressed the [Ca2+]ext-triggered rise in [Ca2+]cyt and downstream changes in gene expression. Taken together, this study demonstrates that [Ca2+]cyt plays an important role in the putative receptor-mediated cellular and transcriptional response to [Ca2+]ext depletion of plant cells. [ABSTRACT FROM AUTHOR]

Dissolved organic carbon (DOC) has received considerable attention in freshwater research, particularly since the early 2000s when increasing trends became apparent. However, remaining questions need to be resolved to address future effects of DOC on surface waters. This study was undertaken to determine (1) the relative importance of acidity and ionic strength in driving DOC increases in waters recovering from acidification and (2) the role played by long-term acid rain effects on soil. Data obtained from temporal and spatial monitoring of 142 headwater streams throughout the Adirondack region of New York (USA) were used to evaluate chemical relationships involving DOC. Year-round monitoring of three streams of differing acidification status were combined with intermittent stream surveys during spring snowmelt throughout this 24,243 km2 region that is recovering from acidification of soils and surface waters. Despite acidic deposition decreases reaching levels estimated for the early 1900s, DOC concentrations exhibited linear increases from the early 2000s through 2019. Ionic strength or conductivity showed consistent inverse relationships with DOC in all data comparisons from 2004‐05 to 2018‐19. In contrast, relationships between pH and DOC did not support increasing pH as an important factor in DOC increases. Inconsistent relationships between pH and DOC were due to strongly acidic organic acids that remain unprotonated throughout the pH range of these waters and limited weak-acid deprotonation below pH 6.2. Decreasing ionic strength increases DOC solubility by expanding the diffuse double layer, which fosters disaggregation of organic matter and dispersion of colloids. This affect controlled DOC solubilization below a pH of approximately 6.2. Distinguishing between ionic strength and pH effects is important because further large reductions in acidic deposition are not expected but continued soil-water dilution is likely from soil-Ca2+ depletion and the decreasing rate of Ca2+ leaching by SO 4 2− and NO 3 −, which are still being released from soil organic matter. Unlabelled Image • DOC in surface waters continues to increase despite low acid rain levels. • Decreases in ionic strength, not acidity are increasing soil carbon solubility. • Soil‑calcium depletion is a key factor in ongoing decreases in ionic strength. • Ionic strength decreases will continue driving further increases in DOC. • pH is not controlling DOC in drainage waters, DOC is instead controlling pH. [ABSTRACT FROM AUTHOR]

Mobilization of toxic forms of aluminum (Al i) have been one of the most harmful effects of acidic deposition on aquatic ecosystems. Large decreases in acidic deposition levels have resulted in decreases in Al i concentrations in surface waters starting in the 1990s. However, recent studies indicate that fish communities are still being impaired by elevated Al i concentrations in streams, suggesting the need for a present-day assessment of the recovery status of Al chemistry in impacted regions such as the Adirondack region of New York, United States. Therefore, the recovery status of Al was assessed from long-term high-frequency monitoring of three Adirondack streams up through 2019, and multiple resampling of 127 headwater streams throughout the Adirondack region between 2004/2005 and 2018/2019. Results indicated that concentrations of Al i have continued to decrease throughout the Adirondack region, but that harmful conditions still exist in a substantial number of streams during spring snowmelt. In the western Adirondack region, 35 percent of streams during spring snowmelt, (typically the most acidic period), and 10 percent of streams during summer were still experiencing harmful concentrations of Al i (>1.0 μmol L−1) in 2018/2019. In the less-impacted east-central Adirondack region, 10 percent of streams during snowmelt, and 4 percent of streams during summer were experiencing harmful Al i concentrations in 2018. Temporal decreases in Al i concentrations were due in part to a shift in speciation from Al i to non-toxic organically complexed Al as dissolved organic carbon concentrations increased, which was also a response to decreasing acidic deposition. Increased availability of calcium resulting from acid-neutralization processes such as weathering also contributed to the decrease in Al i over the past 5–8 years. The current low levels of acidic deposition may have begun to enhance recovery by increasing the effectiveness of ambient acid-neutralization processes. • Toxic aluminum concentrations have continued to decline in Adirondack streams. • Toxic aluminum still occurs in 35% of western Adirondack streams during snowmelt. • Increases in dissolved organic carbon are reducing aluminum toxicity. • Recent rise in calcium availability is lowering toxic aluminum concentrations. • Rise in calcium availability is coincident with recent acid rain reductions. [ABSTRACT FROM AUTHOR]

Simple Summary: Selection for high egg production in laying hens has led to an increased calcium requirement and consequently to an intensified calcium mobilization from the bones. However, excessive demineralization can lead to osteoporosis, which is manifested by a high incidence of bone-damaged hens. In this study, we characterized the adaptation response of laying hens to a repeated dietary calcium restriction (1.09% instead of 4.26% calcium) by means of egg production, eggshell quality, body weight and bone stability. The animal model included four layer lines differing in performance level (high vs. moderately performing lines) and phylogenetic origin (white-egg vs. brown-egg layers). We assumed that the high performing lines would respond by maintaining egg production level at the expense of eggshell quality and bone health. Egg production and eggshell quality declined considerably and bone demineralization occurred in all lines. Contrary to our hypothesis, there was evidence that phylogeny rather than performance level influenced the hens′ response. The brown-egg lines appeared to be more tolerant to the calcium depletion, while the white-egg lines were more sensitive. Our findings demonstrate the influence of genetics on the adaptive capacity of chickens and underline the importance of preserving genetic variability to cope with potential future environmental challenges. In modern laying hybrids, calcium (Ca) homeostasis is immensely challenged by daily eggshell calcification. However, excessive mobilization of Ca from bones may lead to osteoporosis, which then manifests in a high incidence of poor bone quality. The aim of this study was to characterize the hens' adaptation response to an alternating dietary Ca restriction. The animal model consisted of four purebred layer lines, differing in laying performance (high vs. moderately performing lines) and phylogenetic origin (white- vs. brown-egg lines). According to the resource allocation theory, hens selected for high egg production were assumed to show a different response pattern to cope with this nutritive challenge compared to moderately performing lines. Data collected included egg number, egg quality traits, body weight and bone characteristics. The Ca depletion led to a temporary drop in egg production and shell quality and a loss of bone stability due to Ca mobilization. The white-egg lines response was more pronounced, whereas the brown-egg lines were less sensitive towards reduced Ca supply. Our study shows that the hens' responsiveness to coping with a nutritive Ca depletion is not ultimately linked to genetic selection for increased egg production but rather to phylogenetic origin. [ABSTRACT FROM AUTHOR]