The heavy metals biosorption from aqueous solution using microalgae has attracted attention, but studies related to the process of copper biosorption by C. pyrenoidosa are scarce. The present work ...aimed to characterize, verify thermodynamic viability and optimize the copper biosorption by C. pyrenoidosa using a Box-Behnken factorial design. The adsorbent had a particle diameter ranging from 14.13 to 123.6 μm, with macropores of 1.868 ± 0.337 μm. The infrared spectra suggested a physical adsorption mechanism that was later proven by the enthalpy change (48.318 kJ·mol−1) and the parameters obtained from Temkin and Dubinin-Radushkevich isotherms. Furthermore, the process was best described by the Langmuir isotherm and a pseudo second order kinetics. The model optimization was achieved in order to maximize the percentage of copper removal, corresponding to 83.14% when the algae concentration was 1.28 g·L−1, 5 mg·L−1 of copper ions and pH 6.33.
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•Chlorella pyrenoidosa was used as an effective biosorbent for heavy metal.•Chlorella pyrenoidosa characterization was done in terms of its morphology and composition.•Physical adsorption and monolayer sorption were the prevailing sorption mechanisms.•Response surface methodology was used for the biosorption optimization.
•Animals lacking SET-2, the C. elegans orthologue of the SET1 histone methyltransferase, show increased sensitivity to DNA damage.•Sensitivity to DNA damage increases between generations in set-2 ...null mutant animals.•The DNA damage response is intact in set-2 mutants.•set-2 mutants are defective in the repair of induced double strand breaks.
Maintaining the integrity of genetic information across generations is essential for both cell survival and reproduction, and requires the timely repair of DNA damage. Histone-modifying enzymes play a central role in the DNA repair process through the deposition and removal of post-translational modifications on the histone tails. Specific histone modification act in the DNA repair process through the recruitment of proteins and complexes with specific enzymatic activities, or by altering the chromatin state at the site of DNA lesions. The conserved SET1/MLL family of histone methyltransferases (HMT) catalyzes methylation of histone H3 on Lysine 4 (H3K4), a histone modification universally associated with actively transcribed genes. Studies have focused on the role of SET1/MLL proteins in epigenetic regulation of gene expression. Much less is known on their role in the DNA repair process in a developmental context. Here we show that SET-2, the Caenorhabditis elegans orthologue of SET1, is required to preserve germline genome integrity over subsequent generations. Animals lacking the SET-2 catalytic subunit show a transgenerational increase in sensitivity to DNA damage-inducing agents that is accompanied by a defect in double-strand break (DSB) repair and chromosome fragmentation. These defects are not due to a failure to activate the DNA damage response (DDR) that allows detection, signaling and repair of DNA lesions, because cell cycle arrest and apoptosis, key components of this pathway, are efficiently induced in set-2 mutant animal. Rather, our results suggest that SET-2 plays a role in the transgenerational maintenance of genome stability by acting in DNA repair downstream of DDR signaling.
Abstract In neurological disorders, both acute and chronic neural stress can disrupt cellular proteostasis, resulting in the generation of pathological protein. However in most cases, neurons adapt ...to these proteostatic perturbations by activating a range of cellular protective and repair responses, thus maintaining cell function. These interconnected adaptive mechanisms comprise a ‘proteostasis network’ and include the unfolded protein response, the ubiquitin proteasome system and autophagy. Interestingly, several recent studies have shown that these adaptive responses can be stimulated by preconditioning treatments, which confer resistance to a subsequent toxic challenge – the phenomenon known as hormesis. In this review we discuss the impact of adaptive stress responses stimulated in diverse human neuropathologies including Parkinson׳s disease, Wolfram syndrome, brain ischemia, and brain cancer. Further, we examine how these responses and the molecular pathways they recruit might be exploited for therapeutic gain. This article is part of a Special Issue entitled SI:ER stress.
Cellular identity during metazoan development is maintained by epigenetic modifications of chromatin structure brought about by the activity of specific proteins which mediate histone variant ...incorporation, histone modifications, and nucleosome remodeling. HP1 proteins directly influence gene expression by modifying chromatin structure. We previously showed that the
Caenorhabditis elegans HP1 proteins HPL-1 and HPL-2 are required for several aspects of post-embryonic development. To gain insight into how HPL proteins influence gene expression in a developmental context, we carried out a candidate RNAi screen to identify suppressors of
hpl-1 and
hpl-2 phenotypes. We identified SET-2, the homologue of yeast and mammalian SET1, as an antagonist of HPL-1 and HPL-2 activity in growth and somatic gonad development. Yeast Set1 and its mammalian counterparts SET1/MLL are H3 lysine 4 (H3K4) histone methyltransferases associated with gene activation as part of large multisubunit complexes. We show that the nematode counterparts of SET1/MLL complex subunits also antagonize HPL function in post-embryonic development. Genetic analysis is consistent with SET1/MLL complex subunits having both shared and unique functions in development. Furthermore, as observed in other species, we find that SET1/MLL complex homologues differentially affect global H3K4 methylation. Our results suggest that HP1 and a SET1/MLL-related complex may play antagonistic roles in the epigenetic regulation of specific developmental programs.
The nocturnal polyuria is considered a significant predictive value for response to desmopressin. The cutoff value useful to define nocturnal polyuria is still a matter of debate. Moreover, it is ...current notion that maximal voided volume (MVV) could be used as a predictor for desmopressin response.
The objective of this study was to assess the impact of different definitions of nocturnal polyuria (and of its frequency) and MVV in predicting the response to desmopressin.
A total of 103 patients with frequent monosymptomatic nocturnal enuresis (≥4 wet nights/week) were enrolled. A bladder diary over a 4-day period was collected. The MVV was defined as the highest micturition volume detected at bladder diary. Nocturnal diuresis was measured in 5 wet nights. Then, patients were administered with 120 mcg of sublingual desmopressin. After 2 months, if there was no complete response, the dose was increased to 240 mcg. Nocturnal polyuria was defined as follows:
1.Definition 1: nocturnal urine production >130% of the expected bladder capacity (EBC).
2. Definition 2: >100% EBC.
3. Definition 3: > 20×(age + 9) mL.
The primary outcome was ‘response to desmopressin’ after 3 months of treatment.
Fifty-three patients responded to desmopressin. Comparing the responses to desmopressin on the basis of the three definitions of nocturnal polyuria, no significant difference was found. There was no cutoff value of nocturnal polyuria expressed as %EBC useful in providing a significant receiver-operating characteristic (ROC) curve. The area under the ROC curve for MVV expressed as %EBC was 0.67 (95% confidence interval CI, 0.54–0.80; p = 0.01). A MVV >103.1% of EBC had 78.8% (95% CI, 61.1–91.0) sensitivity and 47.5% (95% CI, 31.5–63.9) specificity for predicting response to desmopressin. Among the patients with nocturnal polyuria according to definition 1, a higher percentage of subjects with nocturnal polyuria in 4 out of 5 or 5 out of 5 nights responded to desmopressin, compared with other patients. Patients presenting with nocturnal polyuria according to definition 3 in 5 out of 5 nights showed a 100% of response to desmopressin. At multivariate analysis, the only significant odds ratio (OR) to respond to desmopressin was that of patients with nocturnal polyuria according to definition 1 in >3 nights (OR = 7.1, 95% CI, 1.3–40.3).
The presence or absence of nocturnal polyuria—according to all three definitions—in at least one night was not effective in predicting the response to desmopressin. Predictors of desmopressin response were nocturnal polyuria in >3 out of 5 wet nights according to definition 1 and in 5 out of 5 wet nights according to definition 3. Display omitted
Serine 2 phosphorylation (S2P) within the CTD of RNA polymerase II is considered a Cdk9/Cdk12-dependent mark required for 3'-end processing. However, the relevance of CTD S2P in metazoan development ...is unknown. We show that
lesions or a full-length CTD S2A substitution results in an identical phenotype in
Embryogenesis occurs in the complete absence of S2P, but the hatched larvae arrest development, mimicking the diapause induced when hatching occurs in the absence of food. Genome-wide analyses indicate that when CTD S2P is inhibited, only a subset of growth-related genes is not properly expressed. These genes correspond to SL2 trans-spliced mRNAs located in position 2 and over within operons. We show that CDK-12 is required for maximal occupancy of cleavage stimulatory factor necessary for SL2 trans-splicing. We propose that CTD S2P functions as a gene-specific signaling mark ensuring the nutritional control of the
developmental program.
The Mi-2 protein is the central component of the recently isolated NuRD nucleosome remodelling and histone deacetylase complex. Although the NuRD complex has been the subject of extensive biochemical ...analyses, little is known about its biological function. Here we show that the two C. elegans Mi-2 homologues, LET-418 and CHD-3, play essential roles during development. The two proteins possess both shared and unique functions during vulval cell fate determination, including antagonism of the Ras signalling pathway required for vulval cell fate induction and the proper execution of the 2 degrees cell fate of vulval precursor cells, a process under the control of LIN-12 Notch signalling.
We study first-order systems of two rational difference equations,
In particular, we assume non-negative parameters and non-negative initial conditions. We develop several approaches which allow us ...to resolve some conjectures regarding the boundedness of first-order systems of two rational difference equations.
Heritable inactivation of genes occurs in specific chromosomal domains located at the silent mating type loci and at telomeres of S. cerevisiae. The SIR genes (for silent information regulators) are ...trans-acting factors required for this repression mechanism. We show here that the SIR3 and SIR4 gene products have a sub-nuclear localization similar to the telomere-associated RAP1 protein, which is found primarily in foci at the nuclear periphery of fixed yeast spheroplasts. In strains deficient for either SIR3 or SIR4, telomeres lose their perinuclear localization, as monitored by RAP1 immunofluorescence. The length of the telomeric repeat shortens in sir3 and sir4 mutant strains, and the mitotic stability of chromosome V is reduced. These data suggest that SIR3 and SIR4 are required for both the integrity and subnuclear localization of yeast telomeres, the loss of which correlates with loss of telomere-associated gene repression.
The transcriptional co-regulator SIN3 influences gene expression through multiple interactions that include histone deacetylases. Haploinsufficiency and mutations in SIN3 are the underlying cause of ...Witteveen-Kolk syndrome and related intellectual disability and autism syndromes, emphasizing its key role in development. However, little is known about the diversity of its interactions and functions in developmental processes. Here, we show that loss of SIN-3, the single SIN3 homolog in Caenorhabditis elegans, results in maternal-effect sterility associated with de-regulation of the germline transcriptome, including de-silencing of X-linked genes. We identify at least two distinct SIN3 complexes containing specific histone deacetylases and show that they differentially contribute to fertility. Single-cell, single-molecule fluorescence in situ hybridization reveals that in sin-3 mutants the X chromosome becomes re-expressed prematurely and in a stochastic manner in individual germ cells, suggesting a role for SIN-3 in its silencing. Furthermore, we identify histone residues whose acetylation increases in the absence of SIN-3. Together, this work provides a powerful framework for the in vivo study of SIN3 and associated proteins.
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