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In this paper we establish the convergence of a general primal–dual method for nonsmooth convex optimization problems whose structure is typical in the imaging framework, as, for example, in the Total Variation image restoration problems. When the steplength parameters are a priori selected sequences, the convergence of the scheme is proved by showing that it can be considered as an ε -subgradient method on the primal formulation of the variational problem. Our scheme includes as special case the method recently proposed by Zhu and Chan for Total Variation image restoration from data degraded by Gaussian noise. Furthermore, the convergence hypotheses enable us to apply the same scheme also to other restoration problems, as the denoising and deblurring of images corrupted by Poisson noise, where the data fidelity function is defined as the generalized Kullback–Leibler divergence or the edge preserving removal of impulse noise. The numerical experience shows that the proposed scheme with a suitable choice of the steplength sequences performs well with respect to state-of-the-art methods, especially for Poisson denoising problems, and it exhibits fast initial and asymptotic convergence.

CDKL5 is a kinase with relevant functions in correct neuronal development and in the shaping of synapses. A decrease in its expression or activity leads to a severe neurodevelopmental condition known as CDKL5 deficiency disorder (CDD). CDD arises from CDKL5 mutations that lie in the coding region of the gene. However, the identification of a SNP in the CDKL5 5′UTR in a patient with symptoms consistent with CDD, together with the complexity of the CDKL5 transcript leader, points toward a relevant translational regulation of CDKL5 expression with important consequences in physiological processes as well as in the pathogenesis of CDD. We performed a bioinformatics and molecular analysis of the 5'UTR of CDKL5 to identify translational regulatory features. We propose an important role for structural cis-acting elements, with the involvement of the eukaryotic translational initiation factor eIF4B. By evaluating both cap-dependent and cap-independent translation initiation, we suggest the presence of an IRES supporting the translation of CDKL5 mRNA and propose a pathogenic effect of the C>T -189 SNP in decreasing the translation of the downstream protein.

Fibromyalgia Syndrome (FMS) is a chronic disease characterized by widespread pain, and difficult to diagnose and treat. We analyzed the plasma metabolic profile of patients with FMS by using a metabolomics approach combining Liquid Chromatography-Quadrupole-Time Of Flight/Mass Spectrometry (LC-Q-TOF/MS) with multivariate statistical analysis, aiming to discriminate patients and controls. LC-Q-TOF/MS analysis of plasma (FMS patients: n = 22 and controls: n = 21) identified many lipid compounds, mainly lysophosphocholines (lysoPCs), phosphocholines and ceramides. Multivariate statistical analysis was performed to identify the discriminating metabolites. A protein docking and molecular dynamic (MD) study was then performed, using the most discriminating lysoPCs, to validate the binding to Platelet Activating Factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) Receptor (PAFr). Discriminating metabolites between FMS patients and controls were identified as 1-tetradecanoyl-sn-glycero-3-phosphocholine [PC(14:0/0:0)] and 1-hexadecanoyl-sn-glycero-3-phosphocholine [PC(16:0/0:0)]. MD and docking indicate that the ligands investigated have similar potentialities to activate the PAFr receptor. The application of a metabolomic approach discriminated FMS patients from controls, with an over-representation of PC(14:0/0:0) and PC(16:0/0:0) compounds in the metabolic profiles. These results and the modeling of metabolite-PAFr interaction, allowed us to hypothesize that lipids oxidative fragmentation might generate lysoPCs in abundance, that in turn will act as PAF-like bioactivators. Overall results suggest disease biomarkers and potential therapeutical targets for FMS.

Genetic diversity is what selection acts on, thus shaping the adaptive potential of populations. We studied micro-evolutionary patterns of the key planktonic diatom Pseudo-nitzschia multistriata at a long-term sampling site over 2 consecutive years by genotyping isolates with 22 microsatellite markers. We show that both sex and vegetative growth interplay in shaping intraspecific diversity. We document a brief but massive demographic and clonal expansion driven by strains of the same mating type. The analysis of an extended data set (6 years) indicates that the genetic fingerprint of P. multistriata changed over time with a nonlinear pattern, with intermittent periods of weak and strong diversification related to the temporary predominance of clonal expansions over sexual recombination. These dynamics, rarely documented for phytoplankton, contribute to the understanding of bloom formation and of the mechanisms that drive microevolution in diatoms.

Diatoms are single‐celled organisms that contribute approximately 20% of the global primary production and play a crucial role in biogeochemical cycles and trophic chains. Despite their ecological importance, our knowledge of microevolution is limited. We developed a model using the SLiM evolutionary framework to address this knowledge gap. As a reference, we used the diatom Pseudo‐nitzschia multistriata, which has been extensively studied in the Gulf of Naples. Our model recapitulates what we observe in natural populations, with microevolutionary processes that occur annually during a three‐stage bloom phase. Interestingly, we found that non‐bloom phases allow the population to maintain sex‐generated diversity produced during blooms. This finding suggests that non‐bloom phases are critical to counteract bloom‐related pressures and mitigate genetic divergence at the species level. Moreover, our model showed that despite the consistent genetic differentiation during bloom phases, the population tends to return to pre‐bloom states. While our model is limited to neutral dynamics, our study provides valuable insights into diatoms' microevolution, paving the way to explore the ecological implications of the life history dynamics of these organisms. Diatoms are single‐celled organisms producing blooms crucial in biogeochemical cycles and trophic chains. We simulated neutral microevolutionary dynamics of synthetic diatom populations observing that non‐bloom phases are critical to counteract bloom‐related pressures and mitigate genetic divergence at the species level. Our work contributes to understanding microbial communities' roles in aquatic ecosystems and global biogeochemical cycles.

The processes leading to the emergence of new species are poorly understood in marine plankton, where weak physical barriers and homogeneous environmental conditions limit spatial and ecological segregation. Here, we combine molecular and ecological information from a long‐term time series and propose Pseudo‐nitzschia allochrona, a new cryptic planktonic diatom, as a possible case of speciation by temporal segregation. The new species differs in several genetic markers (18S, 28S and ITS rDNA fragments and rbcL) from its closest relatives, which are morphologically very similar or identical, and is reproductively isolated from its sibling species P. arenysensis. Data from a long‐term plankton time series show P. allochrona invariably occurring in summer–autumn in the Gulf of Naples, where its closely related species P. arenysensis, P. delicatissima, and P. dolorosa are instead found in winter–spring. Temperature and nutrients are the main factors associated with the occurrence of P. allochrona, which could have evolved in sympatry by switching its phenology and occupying a new ecological niche. This case of possible speciation by time shows the relevance of combining ecological time series with molecular information to shed light on the eco‐evolutionary dynamics of marine microorganisms. We describe a new cryptic species in the marine diatom genus Pseudo‐nitzschia, P. allochrona, based on different phylogenetic markers and with the support of mating incompatibility with the sibling species P. arenysensis. Compared with its closest congeneric species in the Gulf of Naples, P. allochrona occupies a distinct temporal niche, which suggests it may have evolved in sympatry by switching its phenology and occupying a new ecological niche.

Understanding the genetic structure of populations and the processes responsible for its spatial and temporal dynamics is vital for assessing species’ adaptability and survival in changing environments. We investigate the genetic fingerprinting of blooming populations of the marine diatom Pseudo-nitzschia multistriata in the Gulf of Naples (Mediterranean Sea) from 2008 to 2020. Strains were genotyped using microsatellite fingerprinting and natural samples were also analysed with Microsatellite Pool-seq Barcoding based on Illumina sequencing of microsatellite loci. Both approaches revealed a clonal expansion event in 2013 and a more stable genetic structure during 2017–2020 compared to previous years. The identification of a mating type (MT) determination gene allowed to assign MT to strains isolated over the years. MTs were generally at equilibrium with two notable exceptions, including the clonal bloom of 2013. The populations exhibited linkage equilibrium in most blooms, indicating that sexual reproduction leads to genetic homogenization. Our findings show that P. multistriata blooms exhibit a dynamic genetic and demographic composition over time, most probably determined by deeper-layer cell inocula. Occasional clonal expansions and MT imbalances can potentially affect the persistence and ecological success of planktonic diatoms.

Diatoms’ bloom dynamics, with seasonal cycling of waxes and wanes of cell abundance, imply frequent bottleneck and expansion events that can leave signatures in the genetic structure and diversity of populations. We explored changes in genetic diversity and structure within multiple species of the planktonic marine diatom genus Pseudo‐nitzschia living in sympatry in the Gulf of Naples (Tyrrhenian Sea, Italy) over 48 sampling dates (from 2011 to 2013) by means of metabarcode data. The genus Pseudo‐nitzschia includes complexes of cryptic species along with morphologically distinguishable ones. We assessed the resolution power of the hypervariable V4 region of the 18S rDNA in delimiting species using different algorithms and a set of reference sequences. We measured intra‐specific genetic diversity and differentiation among species over three annual cycles. Between‐species divergence was higher in the P. pseudodelicatissima complex, while signs of incomplete lineage sorting and/or introgression were detected in the P. delicatissima complex. Most of the species showed significant population differentiation over time, due to changes in haplotypic composition over the three years. Some haplotypes were lost and new ones appeared, with high polymorphism in species of the P. delicatissima complex. We hypothesize that the observed temporal changes in genetic structure result from frequent founder events linked to a population dynamic characterized by cyclical alternation of clonal expansions and bottlenecks and discuss possible factors affecting the microevolutionary pathways in these planktonic diatoms. We explored changes in genetic diversity and structure within multiple species of the planktonic marine diatom genus Pseudo‐nitzschia living in sympatry in the Gulf of Naples (Tyrrhenian Sea, Italy) over 48 sampling dates (from 2011 to 2013) by means of V4 metabarcode data. Most of the species showed significant population differentiation over time, due to changes in haplotypic composition over the three years. Some haplotypes were lost and new ones appeared, with high polymorphism in species of the P. delicatissima complex. We hypothesize that the observed temporal changes in genetic structure result from frequent founder events linked to a population dynamic characterized by cyclical alternation of clonal expansions and bottlenecks and discuss possible factors affecting the microevolutionary pathways in these planktonic diatoms.

Oxylipins are low-molecular weight secondary metabolites derived from the incorporation of oxygen into the carbon chains of polyunsaturated fatty acids (PUFAs). Oxylipins are produced in many prokaryotic and eukaryotic lineages where they are involved in a broad spectrum of actions spanning from stress and defense responses, regulation of growth and development, signaling, and innate immunity. We explored the diversity in oxylipin patterns in the marine planktonic diatom Pseudo-nitzschia. This genus includes several species only distinguishable with the aid of molecular markers. Oxylipin profiles of cultured strains were obtained by reverse phase column on a liquid chromatograph equipped with UV photodiode detector and q-ToF mass spectrometer. Lipoxygenase compounds were mapped on phylogenies of the genus Pseudo-nitzschia inferred from the nuclear encoded hyper-variable region of the LSU rDNA and the plastid encoded rbcL. Results showed that the genus Pseudo-nitzschia exhibits a rich and varied lipoxygenase metabolism of eicosapentaenoic acid (EPA), with a high level of specificity for oxylipin markers that generally corroborated the genotypic delineation, even among genetically closely related cryptic species. These results suggest that oxylipin profiles constitute additional identification tools for Pseudo-nitzschia species providing a functional support to species delineation obtained with molecular markers and morphological traits. The exploration of the diversity, patterns and plasticity of oxylipin production across diatom species and genera will also provide insights on the ecological functions of these secondary metabolites and on the selective pressures driving their diversification.