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1.
J Biomed Opt ; 29(Suppl 2): S22702, 2025 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38434231

RESUMO

Significance: Advancements in label-free microscopy could provide real-time, non-invasive imaging with unique sources of contrast and automated standardized analysis to characterize heterogeneous and dynamic biological processes. These tools would overcome challenges with widely used methods that are destructive (e.g., histology, flow cytometry) or lack cellular resolution (e.g., plate-based assays, whole animal bioluminescence imaging). Aim: This perspective aims to (1) justify the need for label-free microscopy to track heterogeneous cellular functions over time and space within unperturbed systems and (2) recommend improvements regarding instrumentation, image analysis, and image interpretation to address these needs. Approach: Three key research areas (cancer research, autoimmune disease, and tissue and cell engineering) are considered to support the need for label-free microscopy to characterize heterogeneity and dynamics within biological systems. Based on the strengths (e.g., multiple sources of molecular contrast, non-invasive monitoring) and weaknesses (e.g., imaging depth, image interpretation) of several label-free microscopy modalities, improvements for future imaging systems are recommended. Conclusion: Improvements in instrumentation including strategies that increase resolution and imaging speed, standardization and centralization of image analysis tools, and robust data validation and interpretation will expand the applications of label-free microscopy to study heterogeneous and dynamic biological systems.


Assuntos
Técnicas Histológicas , Microscopia , Animais , Citometria de Fluxo , Processamento de Imagem Assistida por Computador
2.
Rev. esp. patol ; 57(2): 137-140, Abr-Jun, 2024. ilus
Artigo em Espanhol | IBECS | ID: ibc-232420

RESUMO

El tumor fibroso calcificante (TFC) es una inusual lesión benigna de origen mesenquimal que puede presentar características similares a otros tumores más comunes. El caso involucra a una mujer de 36 años con un tumor en el yeyuno proximal, inicialmente sospechoso de ser un tumor del estroma gastrointestinal (GIST). Se realiza una resección quirúrgica, revelando un nódulo bien delimitado en el borde antimesentérico con características microscópicas típicas de TFC. Las células tumorales presentaban positividad para CD34 y negatividad para demás marcadores, diferenciándolo de otras neoplasias. El TFC puede confundirse con tumores más comunes debido a su apariencia, pero un diagnóstico preciso respaldado por inmunohistoquímica es esencial. La extirpación quirúrgica completa suele ser curativa. (AU)


Calcifying fibrous tumor (CFT) is a rare benign lesion of mesenchymal origin that may present similar characteristics to other more common tumors. We present the case of a 36-year-old woman with a tumor in the proximal jejunum, initially suspected to be a gastrointestinal stromal tumor (GIST). Surgical resection was performed, revealing a well-demarcated nodule at the anti-mesenteric border with microscopic features typical of a calcifying fibrous tumor. The tumor cells were positive for CD34 and negative for other markers, differentiating it from other neoplasms. Calcifying fibrous tumors can be confused with more common tumors because of its appearance, but an accurate diagnosis supported by immunohistochemistry is essential. Complete surgical excision is usually curative. (AU)


Assuntos
Humanos , Animais , Neoplasias , Células-Tronco Mesenquimais , Imuno-Histoquímica , Ductos Pancreáticos , Ferimentos e Lesões
3.
Harmful Algae ; 135: 102628, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38830707

RESUMO

Diatoms of the genus Pseudo-nitzschia are widespread in marine waters. Some of them can produce the toxin domoic acid (DA) which can be responsible for amnesic shellfish poisoning (ASP) when transferred into the food web. These ASP events are of major concern, due to their ecological and socio-economic repercussions, particularly on the shellfish industry. Many studies have focused on the influence of abiotic factors on DA induction, less on the role of biotic interactions. Recently, the presence of predators has been shown to increase DA production in several Pseudo-nitzschia species, in particular in Arctic areas. In order to investigate the relationship between Pseudo-nitzschia species and grazers from the French coast, exposures between one strain of three species (P. australis, P. pungens, P. fraudulenta) and the copepod Temora longicornis were conducted for 5 days. Cellular and dissolved DA content were enhanced by 1,203 % and 1,556 % respectively after the 5-days exposure of P.australis whereas no DA induction was observed in P. pungens and P. fraudulenta. T. longicornis consumed all three Pseudo-nitzschia species. The copepod survival was not related to DA content. This study is an essential first step to better understanding the interactions between planktonic species from the French coast and highlights the potential key role of copepods in the Pseudo-nitzschia bloom events in the temperate ecosystems.


Assuntos
Copépodes , Diatomáceas , Ácido Caínico , Ácido Caínico/análogos & derivados , Ácido Caínico/metabolismo , Copépodes/fisiologia , Copépodes/metabolismo , Diatomáceas/metabolismo , Diatomáceas/fisiologia , Animais , França , Toxinas Marinhas/metabolismo
4.
Harmful Algae ; 135: 102648, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38830713

RESUMO

Reports of the benthic dinoflagellate Ostreopsis spp. have been increasing in the last decades, especially in temperate areas. In a context of global warming, evidences of the effects of increasing sea temperatures on its physiology and its distribution are still lacking and need to be investigated. In this study, the influence of temperature on growth, ecophysiology and toxicity was assessed for several strains of O. cf. siamensis from the Bay of Biscay (NE Atlantic) and O. cf. ovata from NW Mediterranean Sea. Cultures were acclimated to temperatures ranging from 14.5 °C to 32 °C in order to study the whole range of each strain-specific thermal niche. Acclimation was successful for temperatures ranging from 14.5 °C to 25 °C for O. cf. siamensis and from 19 °C to 32 °C for O. cf. ovata, with the highest growth rates measured at 22 °C (0.54-1.06 d-1) and 28 °C (0.52-0.75 d-1), respectively. The analysis of cellular content of pigments and lipids revealed some aspects of thermal acclimation processes in Ostreopsis cells. Specific capacities of O. cf. siamensis to cope with stress of cold temperatures were linked with the activation of a xanthophyll cycle based on diadinoxanthin. Lipids (neutral reserve lipids and polar ones) also revealed species-specific variations, with increases in cellular content noted under extreme temperature conditions. Variations in toxicity were assessed through the Artemia franciscana bioassay. For both species, a decrease in toxicity was observed when temperature dropped under the optimal temperature for growth. No PLTX-like compounds were detected in O. cf. siamensis strains. Thus, the main part of the lethal effect observed on A. franciscana was dependent on currently unknown compounds. From a multiclonal approach, this work allowed for defining specificities in the thermal niche and acclimation strategies of O. cf. siamensis and O. cf. ovata towards temperature. Potential impacts of climate change on the toxic risk associated with Ostreopsis blooms in both NW Mediterranean Sea and NE Atlantic coast is further discussed, taking into account variations in the geographic distribution, growth abilities and toxicity of each species.


Assuntos
Dinoflagellida , Aquecimento Global , Temperatura , Dinoflagellida/fisiologia , Dinoflagellida/crescimento & desenvolvimento , Mar Mediterrâneo , Proliferação Nociva de Algas , Animais , Aclimatação , Oceanos e Mares
5.
Harmful Algae ; 135: 102632, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38830710

RESUMO

This article presents the first results on shellfish toxicity in the Slovenian sea (Gulf of Trieste, Adriatic Sea) since the analytical methods for the detection of biotoxins (PSP, ASP, DSP and other lipophilic toxins) in bivalve molluscs were included in the national monitoring program in 2013. In addition to toxins, the composition and abundance of toxic phytoplankton and general environmental characteristics of the seawater (surface temperature and salinity) were also monitored. During the 2014-2019 study period, only lipophilic toxins were detected (78 positive tests out of 446 runs), of which okadaic acid (OA) predominated in 97 % of cases, while dinophysistoxin-2 and yessotoxins only gave a positive result in one sampling event each. The number of samples that did not comply with the EC Regulation for the OA group was 17 or 3.8 % of all tests performed, all of which took place from September to November, while a few positive OA tests were also recorded in December, April, and May. This toxicity pattern was consistent with the occurrence pattern of the five most common DSP-producing dinoflagellates, which was supported by the development of warm and thermohaline stratified waters: Dinophysis caudata, D. fortii, D. sacculus, D. tripos and Phalacroma rotundatum. The strong correlation (r = 0.611, p < 0.001) between D. fortii, reaching abundances of up to 950 cells L-1, and OA suggests that D. fortii is the main cause of OA production in Slovenian waters. Strong interannual variations in OA and phytoplankton dynamics, exacerbated by the effects of anthropogenic impacts in this coastal ecosystem, reduce the predictability of toxicity events and require continuous and efficient monitoring. Our results also show that the introduction of the LC-MS/MS method for lipophilic toxins has improved the management of aquaculture activities, which was not as accurate based on mouse bioassays.


Assuntos
Toxinas Marinhas , Mytilus , Ácido Okadáico , Fitoplâncton , Ácido Okadáico/análise , Ácido Okadáico/toxicidade , Animais , Toxinas Marinhas/análise , Eslovênia , Alimentos Marinhos/análise , Água do Mar/química , Dinoflagellida
6.
Harmful Algae ; 135: 102635, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38830716

RESUMO

Ongoing research on cyanotoxins, driven by the socioeconomic impact of harmful algal blooms, emphasizes the critical necessity of elucidating the toxicological profiles of algal cell extracts and pure toxins. This study comprehensively compares Raphidiopsis raciborskii dissolved extract (RDE) and cylindrospermopsin (CYN) based on Daphnia magna assays. Both RDE and CYN target vital organs and disrupt reproduction, development, and digestion, thereby causing acute and chronic toxicity. Disturbances in locomotion, reduced behavioral activity, and weakened swimming capability in D. magna have also been reported for both RDE and CYN, indicating the insufficiency of conventional toxicity evaluation parameters for distinguishing between the toxic effects of algal extracts and pure cyanotoxins. Additionally, chemical profiling revealed the presence of highly active tryptophan-, humic acid-, and fulvic acid-like fluorescence compounds in the RDE, along with the active constituents of CYN, within a 15-day period, demonstrating the chemical complexity and dynamics of the RDE. Transcriptomics was used to further elucidate the distinct molecular mechanisms of RDE and CYN. They act diversely in terms of cytotoxicity, involving oxidative stress and response, protein content, and energy metabolism, and demonstrate distinct modes of action in neurofunctions. In essence, this study underscores the distinct toxicity mechanisms of RDE and CYN and emphasizes the necessity for context- and objective-specific toxicity assessments, advocating nuanced approaches to evaluate the ecological and health implications of cyanotoxins, thereby contributing to the precision of environmental risk assessments.


Assuntos
Alcaloides , Toxinas Bacterianas , Toxinas de Cianobactérias , Cianobactérias , Daphnia , Animais , Toxinas Bacterianas/toxicidade , Daphnia/efeitos dos fármacos , Alcaloides/toxicidade , Cianobactérias/química , Uracila/análogos & derivados , Uracila/toxicidade , Extratos Celulares/química , Extratos Celulares/farmacologia , Proliferação Nociva de Algas
7.
Harmful Algae ; 135: 102634, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38830711

RESUMO

Previous research on phytoplankton blooms has often focused on the initiation of blooms, while studies on the mechanisms underlying bloom decline and termination have been more limited. This study aimed to explore the extent of which Acartia tonsa (copepod) grazing does or does not contribute to Margalefidinium polykrikoides (dinoflagellate) bloom decline. M. polykrikoides is a prominent harmful algal bloom (HAB) species that forms dense blooms in coastal and estuarine systems around the world with known ichthyotoxic effects. Sampling occurred in the lower York River Estuary, Virginia, USA in 2021 and 2022 during two M. polykrikoides blooms. Prey removal experiments were conducted using organisms collected from the field to estimate A. tonsa ingestion rates on M. polykrikoides. While A. tonsa was capable of ingesting M. polykrikoides at low abundance, when M. polykrikoides abundance exceeded 2000 cells mL-1, A. tonsa experienced nearly 100% mortality in the 24-hour prey removal experiments. This suggests that A. tonsa likely cannot exert any top-down control on M. polykrikoides blooms, rather, at high concentrations, M. polykrikoides may act as its own grazing deterrent. Extensive M. polykrikoides blooms could therefore continue to persist due to a reduction in grazing pressure, rather than an increase. This would suggest that the decline of M. polykrikoides blooms is likely caused by another factor. As the frequency, duration, and magnitude of HABs are expected to increase in the future, these findings provide key insights to the trophic interactions that may be influencing the duration of M. polykrikoides blooms.


Assuntos
Copépodes , Dinoflagellida , Proliferação Nociva de Algas , Dinoflagellida/fisiologia , Dinoflagellida/crescimento & desenvolvimento , Animais , Proliferação Nociva de Algas/fisiologia , Copépodes/fisiologia , Virginia , Cadeia Alimentar , Estuários
8.
Harmful Algae ; 135: 102647, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38830717

RESUMO

Cyanobacterial harmful algal blooms (cHABs) are pervasive sources of stress resulting in neurotoxicity in fish. A member of the widely distributed Microcystis genus of bloom-forming cyanobacteria, Microcystis wesenbergii can be found in many freshwater lakes, including Dianchi Lake (China), where it has become one of the dominant contributors to the lake's recurrent blooms. However, unlike its more well-known counterpart M. aeruginosa, the effects of dense non-microcystin-containing M. wesenbergii blooms are seldom studied. The disturbance of appetite regulation and feeding behaviour can have downstream effects on the growth of teleost fish, posing a significant challenge to aquaculture and conservation efforts. Here we examined the effects of M. wesenbergii blooms on the food intake of Acrossocheilus yunnanensis, a native cyprinid in southern China. This fish species has disappeared in Dianchi Lake, and its reintroduction might be negatively affected by the presence of this newly-dominant Microcystis species. We co-cultured juvenile A. yunnanensis with a non-microcystin-producing strain of M. wesenbergii at initial densities between 5 × 104 and 1 × 106 cells/mL and monitored fish feeding behaviour and changes in neurotransmitter and hormone protein levels. High-density M. wesenbergii cultures increased the feeding rate of co-cultured fish, elevating concentrations of appetite-stimulating signalling molecules (Agouti-related protein and γ-aminobutyric acid), while decreasing inhibitory ones (POMC). These changes coincided with histopathological alterations and reduced somatic indices in brain and intestinal tissues. Given this potential for detrimental effects and dysregulation of food intake, further studies are necessary to determine the impacts of chronic exposure of M. wesenbergii in wild fish.


Assuntos
Microcystis , Animais , Microcystis/fisiologia , Proliferação Nociva de Algas , Regulação do Apetite/fisiologia , Cyprinidae/fisiologia , Ingestão de Alimentos , Microcistinas/metabolismo , Lagos , China , Comportamento Alimentar
9.
Neurologia (Engl Ed) ; 39(5): 408-416, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38830720

RESUMO

Ataxias are characterized by aberrant movement patterns closely related to cerebellar dysfunction. Purkinje cell axons are the sole outputs from the cerebellar cortex, and dysfunctional activity of Purkinje cells has been associated with ataxic movements. However, the synaptic characteristics of Purkinje cells in cases of ataxia are not yet well understood. The nicotinamide antagonist 3-acethylpyridine (3-AP) selectively destroys inferior olivary nucleus neurons so it is widely used to induce cerebellar ataxia. Five days after 3-AP treatment (65mg/kg) in adult male Sprague-Dawley rats, motor incoordination was revealed through BBB and Rotarod testing. In addition, in Purkinje cells from lobules V-VII of the cerebellar vermis studied by the Golgi method, the density of dendritic spines decreased, especially the thin and mushroom types. Western blot analysis showed a decrease in AMPA and PSD-95 content with an increase of the α-catenin protein, while GAD-67 and synaptophysin were unchanged. Findings suggest a limited capacity of Purkinje cells to acquire and consolidate afferent excitatory inputs and an aberrant, rigid profile in the movement-related output patterns of Purkinje neurons that likely contributes to the motor-related impairments characteristic of cerebellar ataxias.


Assuntos
Cerebelo , Células de Purkinje , Ratos Sprague-Dawley , Animais , Células de Purkinje/efeitos dos fármacos , Células de Purkinje/patologia , Masculino , Ratos , Cerebelo/efeitos dos fármacos , Ataxia Cerebelar/induzido quimicamente , Piridinas/farmacologia , Plasticidade Neuronal/efeitos dos fármacos
11.
Trop Anim Health Prod ; 56(5): 183, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38831031

RESUMO

This study traced the maternal lineage of the domestic swine populations using mitochondrial DNA control region markers and genetic diversity using microsatellite markers in Uttarakhand, an Indian state situated at the foothills of the world's youngest (geo-dynamically sensitive) mountain system, "the Himalayas". Analysis of 68 maternally unrelated individuals revealed 20 haplotypes. The maternal signature of the Pacific, Southeast Asian, European, and ubiquitously distributed Chinese haplotypes was present in Uttarakhand's domestic pig population. The D3 haplotype reported in wild pigs from North India was also identified in 47 domestic samples. A unique gene pool, UKD (Uttarakhand Domestic), as another lineage specific to this region has been proposed. Genotypes were analyzed, using 13 sets of microsatellite markers. The observed (Ho) and expected (He) heterozygosities were 0.83 ± 0.02 and 0.84 ± 0.01, respectively. The average polymorphic information content value of 0.83 ± 0.01 indicated the high informativeness of the marker. The overall mean FIS value for all the microsatellite markers was low (F = 0.04, P < 0.01). Seven loci deviated from Hardy-Weinberg equilibrium (HWE) at a significant level (p < 0.05). Two clusters were identified, indicating overlapping populations. These results suggested that though belonging to different maternal lineages, the traditional management practices in Uttarakhand have allowed for genetic mixing and the sharing of genetic material among pig populations. It could contribute to increased genetic diversity but might also result in the loss of distinct genetic characteristics or breed purity of the local breeds if not carefully managed.


Assuntos
DNA Mitocondrial , Variação Genética , Haplótipos , Repetições de Microssatélites , Sus scrofa , Animais , DNA Mitocondrial/análise , DNA Mitocondrial/genética , Índia , Sus scrofa/genética , Genética Populacional , Feminino , Genótipo
12.
Mikrochim Acta ; 191(7): 364, 2024 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-38831034

RESUMO

CdIn2S4 and zinc tetrakis(4-carboxyphenyl)porphyrin (ZnTCPP) were synthesized by hydrothermal method, and an organic dye-sensitized inorganic semiconductor ZnTCPP/CdIn2S4 type II heterojunction was constructed on a fluorine-doped tin oxide (FTO) substrate electrode. A sandwich immunostructure for signal-attenuation photoelectrochemical (PEC) detection of cardiac troponin I (cTnI) was constructed using the ZnTCPP/CdIn2S4/FTO photoanode and a horseradish peroxidase (HRP)-ZnFe2O4-Ab2-bovine serum albumin (BSA) immunolabeling complex. The bioenzyme HRP and the HRP-like nanozyme ZnFe2O4 can co-catalyze the oxidation of 4-chloro-1-naphthol (4-CN) by H2O2 to produce an insoluble precipitate on the photoanode, thus notably reducing the anodic photocurrent for quantitative determination of cTnI. Under the optimal conditions, the photocurrent at 0 V vs. SCE in 0.1 M phosphate buffer solution (pH 7.40) containing 0.1 M ascorbic acid was linear with the logarithm of cTnI concentration from 500 fg mL-1 to 50.0 ng mL-1, and the limit of detection (LOD, S/N = 3) is 0.15 pg mL-1. Spiked recoveries were 95.1% ~ 104% for assay of cTnI in human serum samples.


Assuntos
Técnicas Eletroquímicas , Limite de Detecção , Compostos de Estanho , Troponina I , Troponina I/sangue , Humanos , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , Compostos de Estanho/química , Catálise , Peroxidase do Rábano Silvestre/química , Naftóis/química , Metaloporfirinas/química , Eletrodos , Peróxido de Hidrogênio/química , Soroalbumina Bovina/química , Processos Fotoquímicos , Animais , Técnicas Biossensoriais/métodos , Semicondutores , Bovinos , Sulfetos/química , Porfirinas/química
13.
Med Oncol ; 41(7): 167, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38831079

RESUMO

Cancer stem cells (CSCs) are mainly responsible for tumorigenesis, chemoresistance, and cancer recurrence. CSCs growth and progression are regulated by multiple signaling cascades including Wnt/ß-catenin and Hh/GLI-1, which acts independently or via crosstalk. Targeting the crosstalk of signaling pathways would be an effective approach to control the CSC population. Both Wnt/ß-catenin and Hh/GLI-1 signaling cascades are known to be regulated by p53/p21-dependent mechanism. However, it is interesting to delineate whether p21 can induce apoptosis in a p53-independent manner. Therefore, utilizing various subtypes of oral CSCs (SCC9-PEMT p53+/+p21+/+, SCC9-PEMT p53-/-p21+/+, SCC9-PEMT p53+/+p21-/- and SCC9-PEMT p53-/-p21-/-), we have examined the distinct roles of p53 and p21 in Resveratrol nanoparticle (Res-Nano)-mediated apoptosis. It is interesting to see that, besides the p53/p21-mediated mechanism, Res-Nano exposure also significantly induced apoptosis in oral CSCs through a p53-independent activation of p21. Additionally, Res-Nano-induced p21-activation deregulated the ß-catenin-GLI-1 complex and consequently reduced the TCF/LEF and GLI-1 reporter activities. In agreement with in vitro data, similar experimental results were obtained in in vivo mice xenograft model.


Assuntos
Apoptose , Inibidor de Quinase Dependente de Ciclina p21 , Neoplasias Bucais , Nanopartículas , Células-Tronco Neoplásicas , Resveratrol , Proteína Supressora de Tumor p53 , Proteína GLI1 em Dedos de Zinco , beta Catenina , Apoptose/efeitos dos fármacos , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Resveratrol/farmacologia , Proteína GLI1 em Dedos de Zinco/metabolismo , Proteína GLI1 em Dedos de Zinco/genética , beta Catenina/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Humanos , Neoplasias Bucais/patologia , Neoplasias Bucais/tratamento farmacológico , Neoplasias Bucais/metabolismo , Animais , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/genética , Camundongos , Linhagem Celular Tumoral , Ensaios Antitumorais Modelo de Xenoenxerto
14.
J Med Primatol ; 53(3): e12716, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38831476

RESUMO

Neotropical primates rarely exhibit active tuberculosis. A brown howler monkey was found injured in an urban area. Histopathology revealed granulomatous inflammation in the lungs, lymph nodes, and liver. Immunohistochemistry and molecular analysis confirmed the presence of Mycobacterium tuberculosis complex. The findings highlight the importance of TB surveillance in nonhuman primates.


Assuntos
Alouatta , Doenças dos Macacos , Mycobacterium tuberculosis , Tuberculose , Animais , Doenças dos Macacos/microbiologia , Doenças dos Macacos/patologia , Brasil , Mycobacterium tuberculosis/isolamento & purificação , Tuberculose/veterinária , Tuberculose/microbiologia , Tuberculose/patologia , Masculino , Feminino
15.
Biochemistry (Mosc) ; 89(4): 585-600, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38831498

RESUMO

Accurate duplication and separation of long linear genomic DNA molecules is associated with a number of purely mechanical problems. SMC complexes are key components of the cellular machinery that ensures decatenation of sister chromosomes and compaction of genomic DNA during division. Cohesin, one of the essential eukaryotic SMC complexes, has a typical ring structure with intersubunit pore through which DNA molecules can be threaded. Capacity of cohesin for such topological entrapment of DNA is crucial for the phenomenon of post-replicative association of sister chromatids better known as cohesion. Recently, it became apparent that cohesin and other SMC complexes are, in fact, motor proteins with a very peculiar movement pattern leading to formation of DNA loops. This specific process has been called loop extrusion. Extrusion underlies multiple functions of cohesin beyond cohesion, but molecular mechanism of the process remains a mystery. In this review, we summarized the data on molecular architecture of cohesin, effect of ATP hydrolysis cycle on this architecture, and known modes of cohesin-DNA interactions. Many of the seemingly disparate facts presented here will probably be incorporated in a unified mechanistic model of loop extrusion in the not-so-distant future.


Assuntos
Proteínas de Ciclo Celular , Proteínas Cromossômicas não Histona , Coesinas , DNA , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/química , DNA/metabolismo , DNA/química , Humanos , Animais , Trifosfato de Adenosina/metabolismo , Trifosfato de Adenosina/química , Cromátides/metabolismo , Cromátides/química
16.
Biochemistry (Mosc) ; 89(4): 626-636, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38831500

RESUMO

Su(Hw) belongs to the class of proteins that organize chromosome architecture, determine promoter activity, and participate in formation of the boundaries/insulators between the regulatory domains. This protein contains a cluster of 12 zinc fingers of the C2H2 type, some of which are responsible for binding to the consensus site. The Su(Hw) protein forms complex with the Mod(mdg4)-67.2 and the CP190 proteins, where the last one binds to all known Drosophila insulators. To further study functioning of the Su(Hw)-dependent complexes, we used the previously described su(Hw)E8 mutation with inactive seventh zinc finger, which produces mutant protein that cannot bind to the consensus site. The present work shows that the Su(Hw)E8 protein continues to directly interact with the CP190 and Mod(mdg4)-67.2 proteins. Through interaction with Mod(mdg4)-67.2, the Su(Hw)E8 protein can be recruited into the Su(Hw)-dependent complexes formed on chromatin and enhance their insulator activity. Our results demonstrate that the Su(Hw) dependent complexes without bound DNA can be recruited to the Su(Hw) binding sites through the specific protein-protein interactions that are stabilized by Mod(mdg4)-67.2.


Assuntos
Cromatina , Proteínas de Drosophila , Drosophila melanogaster , Proteínas Repressoras , Fatores de Transcrição , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/química , Animais , Cromatina/metabolismo , Fatores de Transcrição/metabolismo , Drosophila melanogaster/metabolismo , Proteínas Repressoras/metabolismo , Proteínas Repressoras/genética , Ligação Proteica , Proteínas Nucleares/metabolismo , Proteínas de Ligação a DNA/metabolismo , Dedos de Zinco , Proteínas Associadas aos Microtúbulos
17.
Biochemistry (Mosc) ; 89(4): 663-673, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38831503

RESUMO

Dosage compensation complex (DCC), which consists of five proteins and two non-coding RNAs roX, specifically binds to the X chromosome in males, providing a higher level of gene expression necessary to compensate for the monosomy of the sex chromosome in male Drosophila compared to the two X chromosomes in females. The MSL2 protein contains the N-terminal RING domain, which acts as an E3 ligase in ubiquitination of proteins and is the only subunit of the complex expressed only in males. Functional role of the two C-terminal domains of the MSL2 protein, enriched with proline (P-domain) and basic amino acids (B-domain), was investigated. As a result, it was shown that the B-domain destabilizes the MSL2 protein, which is associated with the presence of two lysines ubiquitination of which is under control of the RING domain of MSL2. The unstructured proline-rich domain stimulates transcription of the roX2 gene, which is necessary for effective formation of the dosage compensation complex.


Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Domínios Proteicos , Animais , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/química , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Masculino , Feminino , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/química , Ubiquitinação , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/química
18.
Biochemistry (Mosc) ; 89(4): 674-687, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38831504

RESUMO

Chromatin is an epigenetic platform for implementation of DNA-dependent processes. Nucleosome, as a basic level of chromatin compaction, largely determines its properties and structure. In the study of nucleosomes structure and functions physicochemical tools are actively used, such as magnetic and optical "tweezers", "DNA curtains", nuclear magnetic resonance, X-ray crystallography, and cryogenic electron microscopy, as well as optical methods based on Förster resonance energy transfer. Despite the fact that these approaches make it possible to determine a wide range of structural and functional characteristics of chromatin and nucleosomes with high spatial and time resolution, atomic force microscopy (AFM) complements the capabilities of these methods. The results of structural studies of nucleosome focusing on the AFM method development are presented in this review. The possibilities of AFM are considered in the context of application of other physicochemical approaches.


Assuntos
Microscopia de Força Atômica , Nucleossomos , Nucleossomos/química , Nucleossomos/ultraestrutura , Nucleossomos/metabolismo , Microscopia de Força Atômica/métodos , Humanos , DNA/química , DNA/metabolismo , Animais
19.
Biochemistry (Mosc) ; 89(4): 601-625, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38831499

RESUMO

The most prominent representatives of multisubunit SMC complexes, cohesin and condensin, are best known as structural components of mitotic chromosomes. It turned out that these complexes, as well as their bacterial homologues, are molecular motors, the ATP-dependent movement of these complexes along DNA threads leads to the formation of DNA loops. In recent years, we have witnessed an avalanche-like accumulation of data on the process of SMC dependent DNA looping, also known as loop extrusion. This review briefly summarizes the current understanding of the place and role of cohesin-dependent extrusion in cell physiology and presents a number of models describing the potential molecular mechanism of extrusion in a most compelling way. We conclude the review with a discussion of how the capacity of cohesin to extrude DNA loops may be mechanistically linked to its involvement in sister chromatid cohesion.


Assuntos
Proteínas de Ciclo Celular , Proteínas Cromossômicas não Histona , Coesinas , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/química , Humanos , Adenosina Trifosfatases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Complexos Multiproteicos/metabolismo , Complexos Multiproteicos/química , DNA/metabolismo , DNA/química , Animais , Cromátides/metabolismo
20.
Biochemistry (Mosc) ; 89(4): 688-700, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38831505

RESUMO

Eukaryotic cells are characterized by a high degree of compartmentalization of their internal contents, which ensures precise and controlled regulation of intracellular processes. During many processes, including different stages of transcription, dynamic membraneless compartments termed biomolecular condensates are formed. Transcription condensates contain various transcription factors and RNA polymerase and are formed by high- and low-specificity interactions between the proteins, DNA, and nearby RNA. This review discusses recent data demonstrating important role of nonspecific multivalent protein-protein and RNA-protein interactions in organization and regulation of transcription.


Assuntos
Transcrição Gênica , Humanos , Fatores de Transcrição/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , DNA/metabolismo , DNA/química , RNA/metabolismo , RNA/química , Condensados Biomoleculares/metabolismo , Condensados Biomoleculares/química , Animais , Regulação da Expressão Gênica
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