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1.
Nat Rev Genet ; 23(8): 505-518, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35256818

RESUMO

The AID/APOBEC polynucleotide cytidine deaminases have historically been classified as either DNA mutators or RNA editors based on their first identified nucleic acid substrate preference. DNA mutators can generate functional diversity at antibody genes but also cause genomic instability in cancer. RNA editors can generate informational diversity in the transcriptome of innate immune cells, and of cancer cells. Members of both classes can act as antiviral restriction factors. Recent structural work has illuminated differences and similarities between AID/APOBEC enzymes that can catalyse DNA mutation, RNA editing or both, suggesting that the strict functional classification of members of this family should be reconsidered. As many of these enzymes have been employed for targeted genome (or transcriptome) editing, a more holistic understanding will help improve the design of therapeutically relevant programmable base editors.


Assuntos
Citidina Desaminase , RNA , Citidina Desaminase/química , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , DNA/genética , DNA/metabolismo , Desaminação , RNA/genética , RNA/metabolismo , Edição de RNA
2.
Proc Natl Acad Sci U S A ; 121(17): e2312330121, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38625936

RESUMO

The apolipoprotein B messenger RNA editing enzyme, catalytic polypeptide (APOBEC) family is composed of nucleic acid editors with roles ranging from antibody diversification to RNA editing. APOBEC2, a member of this family with an evolutionarily conserved nucleic acid-binding cytidine deaminase domain, has neither an established substrate nor function. Using a cellular model of muscle differentiation where APOBEC2 is inducibly expressed, we confirmed that APOBEC2 does not have the attributed molecular functions of the APOBEC family, such as RNA editing, DNA demethylation, and DNA mutation. Instead, we found that during muscle differentiation APOBEC2 occupied a specific motif within promoter regions; its removal from those regions resulted in transcriptional changes. Mechanistically, these changes reflect the direct interaction of APOBEC2 with histone deacetylase (HDAC) transcriptional corepressor complexes. We also found that APOBEC2 could bind DNA directly, in a sequence-specific fashion, suggesting that it functions as a recruiter of HDAC to specific genes whose promoters it occupies. These genes are normally suppressed during muscle cell differentiation, and their suppression may contribute to the safeguarding of muscle cell fate. Altogether, our results reveal a unique role for APOBEC2 within the APOBEC family.


Assuntos
Cromatina , Proteínas Musculares , Desaminases APOBEC/genética , Desaminase APOBEC-1/genética , Diferenciação Celular/genética , Cromatina/genética , Citidina Desaminase/metabolismo , DNA , Fibras Musculares Esqueléticas/metabolismo , Proteínas Musculares/metabolismo , Mioblastos/metabolismo , RNA Mensageiro/genética , Animais , Camundongos
3.
Nano Lett ; 24(35): 10908-10914, 2024 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-39168468

RESUMO

Colloidal quantum dots (cQDs), semiconductor materials with widely tunable properties, can be printed in submicrometer patterns through electrohydrodynamic printing, avoiding aggressive photolithography steps. Postprinting ligand exchange determines the final optoelectronic properties of the cQD structures. However, achieving a complete bulk exchange is challenging, and the conventional vibrational analysis lacks the required spatial resolution. Infrared nanospectroscopy enables quantitative analysis of vibrational signals and structural topography on the nanometer scale upon ligand substitution on lead sulfide cQDs. A solution of ethanedithiol led to rapid (∼60 s) exchange of ≤90% of the ligands, in structures up to ∼750 nm thick. Prolonged exposures (>1 h) caused the degradation of the microstructures, with a systematic removal of cQDs regulated by surface:bulk ratios and solvent interactions. This study establishes a method for the development of devices through a combination of tunable photoactive materials, additive manufacturing of microstructures, and their quantitative nanometer-scale analysis.

4.
Ann Hematol ; 103(8): 2845-2851, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38884787

RESUMO

FLT3-ITD and NPM1 mutations are key to defining the genetic risk profile of acute myeloid leukemia (AML). We aimed to assess the prognostic features of the FLT3-ITD and NPM1 mutations in old and/or unfit individuals with AML treated with non-intensive therapies in the era before azacitidine-venetoclax approbation. The results of various non-intensive regimens were also compared. We conducted a retrospective analysis that included patients treated with different non-intensive regimens, between 2007 and 2020 from PETHEMA AML registry. We compiled 707 patients with a median age of 74 years and median follow-up time of 37.7 months. FLT3-ITD patients (N = 98) showed a non-significant difference in overall survival (OS) compared to FLT3-ITD negative-patients (N = 608) (P = 0.17, median OS was 5 vs 7.3 months respectively). NPM1-mutated patients (N = 144) also showed a non-significant difference with NPM1 wild type (N = 519) patients (P = 0.25, median OS 7.2 vs 6.8 respectively). In the Cox regression analysis neither NPM1 nor FLT3-ITD nor age were significant prognostic variables for OS prediction. Abnormal karyotype and a high leukocyte count showed a statistically significant deleterious effect. Azacitidine also showed better survival compared to FLUGA (low dose cytarabine plus fludarabine). NPM1 and FLT3-ITD seem to lack prognostic value in older/unfit AML patients treated with non-intensive regimens other than azacitidine-venetoclax combination.


Assuntos
Leucemia Mieloide Aguda , Mutação , Proteínas Nucleares , Nucleofosmina , Tirosina Quinase 3 Semelhante a fms , Idoso , Feminino , Humanos , Masculino , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Tirosina Quinase 3 Semelhante a fms/genética , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/diagnóstico , Proteínas Nucleares/genética , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida , Vidarabina/análogos & derivados , Vidarabina/uso terapêutico , Vidarabina/administração & dosagem
5.
J Anim Breed Genet ; 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38967062

RESUMO

The current work aimed to identify genomic regions and candidate genes associated with resilience in pigs. In previous work, we proposed the body weight deviation from the expected growth curve (ΔBW) and the increase of the positive acute-phase protein haptoglobin (ΔHP) after a vaccine challenge as resilience indicators which may be improved through selective breeding in pigs. Individuals with steady growth rate and minor activation of haptoglobin (high ΔBW and low ΔHP values) were considered resilient. In contrast, pigs with perturbed growth rate and high activation of haptoglobin (low ΔBW and high ΔHP values) were considered susceptible. Both ∆BW and ∆HP were simultaneously considered to select the most resilient (N = 40) and susceptible (N = 40) pigs. A genome-wide association study was carried out for the pigs' response classification to the challenge test using whole-genome sequence data (7,760,720 variants). Eleven associated genomic regions were identified, harbouring relevant candidate genes related to the immune response (such as pro- and anti-inflammatory responses) and growth pathways. These associated genomic regions harboured 41 potential functional mutations (frameshift, splice donor, splice acceptor, start loss and stop loss/gain) in candidate genes. Overall, this study advances our knowledge about the genetic determinism of resilience, highlighting its polygenic nature and strong relationship with immunity and growth.

6.
Angew Chem Int Ed Engl ; 63(31): e202319344, 2024 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-38519422

RESUMO

Amino acids (AAs) are modular building blocks which nature uses to synthesize both macromolecules, such as proteins, and small molecule natural products, such as alkaloids and non-ribosomal peptides. While the 20 main proteinogenic AAs display relatively limited side chain diversity, a wide range of non-canonical amino acids (ncAAs) exist that are not used by the ribosome for protein synthesis, but contain a broad array of structural features and functional groups. In this communication, we report the discovery of the biosynthetic pathway for a new ncAA, pazamine, which contains a cyclopropane ring formed in two steps. In the first step, a chlorine is added onto the C4 position of lysine by a radical halogenase, PazA. The cyclopropane ring is then formed in the next step by a pyridoxal-5'-phosphate-dependent enzyme, PazB, via an SN2-like attack at C4 to eliminate chloride. Genetic studies of this pathway in the native host, Pseudomonas azotoformans, show that pazamine potentially inhibits ethylene biosynthesis in growing plants based on alterations in the root phenotype of Arabidopsis thaliana seedlings. We further show that PazB can be utilized to make an alternative cyclobutane-containing AA. These discoveries may lead to advances in biocatalytic production of specialty chemicals and agricultural biotechnology.


Assuntos
Aminoácidos , Halogenação , Aminoácidos/metabolismo , Aminoácidos/química , Aminoácidos/biossíntese , Fosfato de Piridoxal/metabolismo , Fosfato de Piridoxal/química , Arabidopsis/metabolismo , Arabidopsis/enzimologia , Pseudomonas/metabolismo , Pseudomonas/enzimologia , Ciclopropanos/química , Ciclopropanos/metabolismo
7.
Ann Allergy Asthma Immunol ; 130(5): 637-648.e5, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36596337

RESUMO

BACKGROUND: Immunoglobulin E (IgE)-mediated food allergies (FAs) are increasingly common among US children and adults. Not only can living with FA impose considerable physical health impacts, but it also imposes economic burden and can negatively affect quality of life. Limited data indicate that allergy to multiple foods (multi-FA) also may be common, but much remains unknown about its distribution and determinants. OBJECTIVE: To characterize the prevalence, characteristics, determinants, psychosocial burden, and distribution of multi-FA among a large, nationally representative sample of US children and adults. METHODS: A US population-based survey was administered. Estimates of multi-FA prevalence, conditional frequencies of multi-FA combinations, and associated factors were derived. Latent class analyses were conducted using 9 dichotomized indicators of specific FA prevalence, which were used to determine factors associated with latent class membership and characterize FA-related psychosocial burden within each class. RESULTS: Surveys were completed for 38,408 children and 40,443 adults. Among children and adults meeting established symptom-report criteria for FA, an estimated 40% and 48% had multi-FA, respectively. Among pediatric and adult populations with convincing FAs, the lifetime reported prevalence of physician-diagnosed atopic comorbidities increased significantly as the number of reported current convincing FAs increased, as did the proportion reporting multi-FA-related health care utilization and higher perceived psychosocial burden. Latent class analyses suggested the existence of the following 4 key latent phenotypes of multi-FA: milk and egg-dominant, seafood-dominant, peanut and tree nut-dominant, and broadly multi-food allergic. CONCLUSION: The US population-level burden of multi-FA is high among both children and adults, and data indicate the presence of 4 major phenotypes of multi-FA in both populations.


Assuntos
Hipersensibilidade Alimentar , Qualidade de Vida , Estados Unidos/epidemiologia , Humanos , Alérgenos , Alimentos , Inquéritos e Questionários , Prevalência
8.
Cryo Letters ; 44(5): 274-279, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38032307

RESUMO

BACKGROUND: N. wightii (Leguminosae) is valued as a cover crop and as a potential source of protein in food insecure countries. However, plantlet establishment is limited by physical dormancy. Our previous work has shown that exposure of N. wightii seeds to cryogenic temperatures is able to overcome physical dormancy. OBJECTIVE: The current study is an extension of that work where the field performance and nutritional composition of plants regenerated from N. wightii seeds was investigated. RESULTS: It was evident that plants regenerated from cryopreserved seeds displayed faster growth rates than those from control seeds. In addition, cryopreservation did not alter the nutritional profile of plants produced from cryo-stored seeds. CONCLUSION: Collectively, the results indicate that cryopreservation serves as a suitable strategy for the preservation of seeds of N. wightii with the added benefit of also serving as a dormancy breaking mechanism upon retrieval from cryogenic temperatures. Doi.org/10.54680/fr23510110712.


Assuntos
Criopreservação , Fabaceae , Estado Nutricional , Sementes , Temperatura
9.
Cryo Letters ; 44(6): 369-377, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38311931

RESUMO

BACKGROUND: Cryopreservation currently represents the most suitable strategy for the long-term conservation of plant germplasm. While much effort has focused on the development of protocols to enable successful cryostorage, there are few, if any reports, that consider the effect of cryogenic temperatures on the phytohormone status of the seed and developing seedlings. OBJECTIVE: To investigate the effect of cryopreservation on external seed coat features as well as levels of indole-3-acetic acid (IAA), abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) in maize. MATERIALS AND METHODS: Two groups of seeds at 6% moisture content were compared: one was maintained at 4 degree C (control) while the other was exposed to LN within cryo-vials. RESULTS: Seeds exposed to cryogenic temperatures were characterized by the presence of large cracks in the seed coat compared with control seeds. Cryogenic exposure also resulted in a reduction in biomass and plant height. Results from the phytohormone analysis showed an initial reduction in the levels of IAA, ABA and ACC after 7 days of growth followed by sharp increase in levels relative to the control by 14 days. Whilst the roles of ABA and ethylene (and by extension, its precursor ACC) are well studied as stress response molecules, much less is known about the potentially vital role of auxins in regulating plant growth under conditions of low temperature stress. CONCLUSION: It is postulated that the interaction of all three hormones modulate crosstalk between various stress responses and recovery pathways to ameliorate the damage caused by freezing stress and enable plant survival. Given the dearth of information on phytohormones in cryobiology, more studies are needed to fully elucidate these relationships in the context of freezing stress caused by liquid nitrogen. Doi.org/10.54680/fr23610110612.


Assuntos
Reguladores de Crescimento de Plantas , Zea mays , Reguladores de Crescimento de Plantas/farmacologia , Reguladores de Crescimento de Plantas/metabolismo , Criopreservação , Ácido Abscísico/farmacologia , Sementes/fisiologia , Nitrogênio
10.
Worldviews Evid Based Nurs ; 20(2): 153-161, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36604994

RESUMO

BACKGROUND: Nursing students experience higher stress and burnout compared to students in other health professions, with a prevalence rate of as high as 20%. More recently, they have been affected by changes in nursing education due to the COVID-19 pandemic, such as requirements for social isolation and distance learning. Although there are existing studies on interventions that address academic burnout among nursing students, there is no synthesis of randomized trials on this topic. AIM: This study aimed to systematically synthesize studies of interventions for academic burnout among nursing students. METHODS: A systematic search for randomized controlled trials was performed in PubMed, CINAHL, CENTRAL, Web of Science, and Scopus. Eligibility criteria were based on study directness in relation to the Patient, Intervention, Comparison, and Outcome (PICO) question. Two review authors independently screened articles for inclusion, collected data from the included studies, and performed risk of bias assessments using the Cochrane Risk of Bias Tool 2.0. A narrative synthesis was performed. This review was registered a priori in PROSPERO (CRD42022350196). RESULTS: Six papers were included in this review. Various interventions were studied: Qigong exercises, progressive muscle relaxation, autogenic therapy and laughter therapy, didactic behavioral sessions focusing on personal and professional development, and coping skills enhancement. The effects of these interventions on academic burnout, depression, and stress among nursing students were short term and their benefits over time remain uncertain. LINKING EVIDENCE TO ACTION: Progressive muscle relaxation and cognitive behavioral interventions demonstrated short-term positive effects on academic burnout, depression, and stress among nursing students. These findings may support the development of individual-level and organizational-level initiatives for nursing students aimed to lessen or prevent academic burnout. Large-scale, high-quality studies on the effect of interventions on academic burden in various settings and cultures are needed.


Assuntos
Esgotamento Profissional , COVID-19 , Estudantes de Enfermagem , Humanos , Pandemias , Esgotamento Profissional/terapia , Adaptação Psicológica
11.
Ann Oncol ; 33(4): 384-394, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35093516

RESUMO

BACKGROUND: Primary analyses of the phase III BrighTNess trial showed addition of carboplatin with/without veliparib to neoadjuvant chemotherapy significantly improved pathological complete response (pCR) rates with manageable acute toxicity in patients with triple-negative breast cancer (TNBC). Here, we report 4.5-year follow-up data from the trial. PATIENTS AND METHODS: Women with untreated stage II-III TNBC were randomized (2 : 1 : 1) to paclitaxel (weekly for 12 doses) plus: (i) carboplatin (every 3 weeks for four cycles) plus veliparib (twice daily); (ii) carboplatin plus veliparib placebo; or (iii) carboplatin placebo plus veliparib placebo. All patients then received doxorubicin and cyclophosphamide every 2-3 weeks for four cycles. The primary endpoint was pCR. Secondary endpoints included event-free survival (EFS), overall survival (OS), and safety. Since the co-primary endpoint of increased pCR with carboplatin plus veliparib with paclitaxel versus carboplatin with paclitaxel was not met, secondary analyses are descriptive. RESULTS: Of 634 patients, 316 were randomized to carboplatin plus veliparib with paclitaxel, 160 to carboplatin with paclitaxel, and 158 to paclitaxel. With median follow-up of 4.5 years, the hazard ratio for EFS for carboplatin plus veliparib with paclitaxel versus paclitaxel was 0.63 [95% confidence interval (CI) 0.43-0.92, P = 0.02], but 1.12 (95% CI 0.72-1.72, P = 0.62) for carboplatin plus veliparib with paclitaxel versus carboplatin with paclitaxel. In post hoc analysis, the hazard ratio for EFS was 0.57 (95% CI 0.36-0.91, P = 0.02) for carboplatin with paclitaxel versus paclitaxel. OS did not differ significantly between treatment arms, nor did rates of myelodysplastic syndromes, acute myeloid leukemia, or other secondary malignancies. CONCLUSIONS: Improvement in pCR with the addition of carboplatin was associated with long-term EFS benefit with a manageable safety profile, and without increasing the risk of second malignancies, whereas adding veliparib did not impact EFS. These findings support the addition of carboplatin to weekly paclitaxel followed by doxorubicin and cyclophosphamide neoadjuvant chemotherapy for early-stage TNBC.


Assuntos
Terapia Neoadjuvante , Neoplasias de Mama Triplo Negativas , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Benzimidazóis , Carboplatina , Ciclofosfamida , Doxorrubicina , Feminino , Seguimentos , Humanos , Paclitaxel , Neoplasias de Mama Triplo Negativas/patologia
12.
BMC Vet Res ; 18(1): 58, 2022 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-35086534

RESUMO

BACKGROUND: Caprine tuberculosis (TB) is a zoonosis caused by members of the Mycobacterium tuberculosis complex (MTBC). Caprine TB control and eradication programmes have traditionally been based on intradermal tuberculin tests and slaughterhouse surveillance. However, this strategy has limitations in terms of sensitivity and specificity. Different factors may affect the performance of the TB diagnostic tests used in goats and, subsequently, the detection of TB-infected animals. In the present study, the effect of two of the factors that may affect the performance of the techniques used to diagnose TB in goats, the topical administration of corticosteroids and a recent pre-sensitisation with tuberculin, was analysed. METHODS: The animals (n = 151) were distributed into three groups: (1) a group topically treated with corticosteroids 48 h after intradermal tuberculin tests (n = 53); (2) a group pre-sensitised with bovine and avian purified protein derivatives (PPDs) 3 days before the intradermal tuberculin test used for TB diagnosis (n = 48); and (3) a control group (n = 50). All the animals were tested using single and comparative intradermal tuberculin (SIT and CIT, respectively) tests, an interferon-gamma release assay (IGRA) and a P22 ELISA. RESULTS: The number of SIT test reactors was significantly lower in the group treated with corticosteroids when compared to the pre-sensitised (p < 0.001) and control (p = 0.036) groups. In contrast, pre-sensitisation with bovine and avian PPDs did not cause a significant reduction in the number of SIT and CIT test reactors compared with the control group. In fact, a higher number of reactors was observed after the prior tuberculin injection in the pre-sensitised group (p > 0.05). No significant effect was observed on IGRA and P22 ELISA due to corticosteroids administration. Nevertheless, a previous PPD injection affected the IGRA performance in some groups. CONCLUSIONS: The application of topical corticosteroid 24 h before reading the SIT and CIT tests can reduce the increase in skin fold thickness and subsequently significantly decrease the number of positive reactors. Corticosteroids used can be detected in hair samples. A previous pre-sensitisation with bovine and avian PPDs does not lead to a significant reduction in the number of intradermal tests reactors. These results are valuable in order to improve diagnosis of caprine TB and detect fraudulent activities in the context of eradication programs.


Assuntos
Doenças dos Bovinos , Doenças das Cabras , Tuberculose , Administração Tópica , Corticosteroides/uso terapêutico , Animais , Bovinos , Doenças das Cabras/diagnóstico , Doenças das Cabras/tratamento farmacológico , Doenças das Cabras/epidemiologia , Cabras , Sensibilidade e Especificidade , Tuberculina , Teste Tuberculínico/veterinária , Tuberculose/diagnóstico , Tuberculose/tratamento farmacológico , Tuberculose/veterinária
13.
Mol Divers ; 26(6): 3399-3409, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35143033

RESUMO

The rise of antimicrobial-resistant phenotypes and the spread of the global pandemic of COVID-19 are worsening the outcomes of hospitalized patients for invasive fungal infections. Among them, candidiases are seriously worrying, especially since the currently available drug armamentarium is extremely limited. We recently reported a new class of macrocyclic amidinoureas bearing a guanidino tail as promising antifungal agents. Herein, we present the design and synthesis of a focused library of seven derivatives of macrocyclic amidinoureas, bearing a second phenyl ring fused with the core. Biological activity evaluation shows an interesting antifungal profile for some compounds, resulting to be active on a large panel of Candida spp. and C. neoformans. PAMPA experiments for representative compounds of the series revealed a low passive diffusion, suggesting a membrane-based mechanism of action or the involvement of active transport systems. Also, compounds were found not toxic at high concentrations, as assessed through MTT assays.


Assuntos
COVID-19 , Cryptococcus neoformans , Antifúngicos/farmacologia , Testes de Sensibilidade Microbiana , Candida
14.
ScientificWorldJournal ; 2022: 2711466, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36479552

RESUMO

Future scientific and technological evolution in many areas of applied mathematics and modern physics will necessarily depend on dealing with complex systems. Such systems are complex in both their composition and behavior, namely, dealing with complex dynamical systems using different types of Duffing equations, such as real Duffing equations and complex Duffing equations. In this paper, we derive an analytical solution to a complex Duffing equation. We extend the Krýlov-Bogoliúbov-Mitropólsky method for solving a coupled system of nonlinear oscillators and apply it to solve a generalized form of a complex Duffing equation.

15.
ScientificWorldJournal ; 2022: 4808065, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36341161

RESUMO

In this paper, we obtain the approximate value of 42.9815 arcsec/century for Mercury's perihelion precession by solving both numerically and analytically the nonlinear ordinary differential equation derived from the geodesic equation in Einstein's Theory of Relativity. We also compare our result with known results, and we illustrate graphically the way Mercury's perihelion moves. The results we obtained are applicable to any body that moves around the Sun. We give predictions about the value of the Cosmological Constant. Simple algebraic formulas allow to estimate perihelion shifts with high accuracy.

16.
ScientificWorldJournal ; 2022: 3240918, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35655902

RESUMO

In this paper, some exact traveling wave solutions to the integrable Gardner equation are reported. The ansatz method is devoted for deriving some exact solutions in terms of Jacobi and Weierstrass elliptic functions. The obtained analytic solutions recover the solitary waves, shock waves, and cnoidal waves. Also, the relation between the Jacobi and Weierstrass elliptic functions is obtained. In the second part of this work, we derive some approximate analytic and numeric solutions to the nonintegrable forced damped Gardner equation. For the approximate analytic solutions, the ansatz method is considered. With respect to the numerical solutions, the evolution equation is solved using both the finite different method (FDM) and cubic B-splines method. A comparison between different approximations is reported.

17.
Cryo Letters ; 43(6): 341-348, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36629829

RESUMO

BACKGROUND: Swietenia mahagoni wood is one of the most valuable in world trade and, as a result, natural populations have been decimated due to unsustainable harvesting. The decline in natural population levels is being exacerbated by climate change. In order to ensure the preservation of valuable genotypes, there is an urgent need to develop strategies to conserve the genetic diversity present within this species. At present, cryopreservation is the most viable option for the long-term storage of plant germplasm, particularly for long-lived species which are challenging to maintain in the field. OBJECTIVE: To cryopreserve intact seeds of S. mahagoni, with the dual goal of retaining the biosynthetic capacity of plants, which is critical since this species is highly valued for medicinal purposes. MATERIALS AND METHODS: Seeds at a moisture content of 6% were immersed in liquid nitrogen (LN) before warming and recovery. Plantlet establishment and growth were assessed over a period of 70 days and anthraquinone synthesis was determined in roots, stems and leaves. RESULTS: The results showed an initial lag in the germination rate of cryopreserved seeds compared with control seeds; however, this difference disappeared over time. The lag in seedling emergence observed in cryostored seeds was also evident in the plant characteristics measured following 30 days of culture when all plant parameters measured were significantly higher in plants produced from control than cryostored seeds. However, after 70 days of growth, these differences were no longer apparent. Anthraquinone levels were also initially lower (at 30 days) in plants regenerated from cryopreserved seeds than those from control seeds, however, this difference was substantially reduced by 70 days thereby indicating the ability of these plants to accumulate secondary metabolites, albeit at a reduced rate, during the early stages of development. CONCLUSION: In S. mahagoni, the delay in anthraquinone production in plants regenerated from cryostored seeds during the early stages of development may have occurred as a consequence of the preferential allocation of resources towards the initiation of recovery processes in response to the stresses imposed by cryopreservation. Once the stresses were overcome and plant growth resumed, resources could be directed to secondary processes such as anthraquinone synthesis. doi.org/10.54680/fr22610110412.


Assuntos
Criopreservação , Meliaceae , Criopreservação/métodos , Sementes/fisiologia , Plântula , Germinação/fisiologia , Plantas
18.
Cryo Letters ; 43(1): 58-65, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35315871

RESUMO

BACKGROUND: Trees within the Calophyllum genus are multi-use trees that produce valuable wood, phytochemicals with a range of biological activities, and seed oil as a source of biodiesel. As a consequence of climate change, there is a need to develop strategies to preserve valuable plant genetic resources. Cryopreservation represents the most suitable option for the long-term storage of germplasm with minimal space and maintenance requirements. OBJECTIVE: To determine appropriate methods to cryopreserve seeds of Calophyllum antillanum and maintain secondary compound production. MATERIALS AND METHODS: Seeds at a moisture content of 6% were used to evaluate two treatments: seeds immersed in liquid nitrogen and control seeds. Biosynthetic pathway efficiency was assessed post-cryo by determining anthraquinone contents in roots, stems and leaves following 30 and 75 d of seedling growth. RESULTS: The results indicated that exposure to liquid nitrogen delayed germination and seedling emergence for a period of up to 45 d after seed sowing. By 60 d of cultivation, no significant differences in plant growth were observed for cryostored and control seeds. The levels of anthraquinones, which were also measured in seeds and seedlings, were lower in plants regenerated from cryostored seeds following 30 d of growth, but there were no differences in roots and stems by 75 d of growth. Furthermore, the difference in leaf anthraquinone levels for cryopreserved and control seeds at 75 d was much smaller than at 30 d. CONCLUSION: The low initial anthraquinone levels in emerging seedlings correlated with the initial slow growth of cryopreserved seeds.


Assuntos
Calophyllum , Plântula , Antraquinonas/farmacologia , Criopreservação/métodos , Nitrogênio/química , Folhas de Planta , Sementes
19.
Hist Philos Life Sci ; 44(1): 3, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-35103850

RESUMO

Tobacco mosaic virus (TMV) has served as a model organism for pathbreaking work in plant pathology, virology, biochemistry and applied genetics for more than a century. We were intrigued by a photograph published in Phytopathology in 1934 showing that Tabasco pepper plants responded to TMV infection with localized necrotic lesions, followed by abscission of the inoculated leaves. This dramatic outcome of a biological response to infection observed by Francis O. Holmes, a virologist at the Rockefeller Institute for Medical Research, was used to score plants for resistance to TMV infection. Our objective was to gain a better understanding of early to mid-twentieth century ideas of genetic resistance to viruses in crop plants. We investigated Holmes' observation as a practical exercise in reworking an experiment, having been inspired by Pamela Smith's innovative Making and Knowing Project. We had a great deal of difficulty replicating Holmes' experiment, finding that biological materials and experimental customs change over time, in ways that ideas do not. Using complementary tools plus careful study and interpretation of the original text and figures, we were able to rework, yet only partially replicate, this experiment. Reading peer-reviewed manuscripts that cited Holmes' 1934 report provided an additional level of insight into the interpretation and replication of this work in the decades that followed. From this, we touch on how experimental reworking can inform our strategies to address the reproducibility "crisis" in twenty-first century science.


Assuntos
Vírus do Mosaico do Tabaco , Plantas , Reprodutibilidade dos Testes , Nicotiana
20.
Cryo Letters ; 42(2): 106-110, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33970987

RESUMO

BACKGROUND: Teramnus labialis (L.f.) Spreng is a potentially important legume species, and can be used as an animal feed and to enhance soil physicochemical characteristics. Despite the biological and agricultural importance, the low availability of seeds, their small size and the low percentage germination limit their large-scale use by farmers. We previously reported a method to cryopreserve seeds of T. labialis which also allowed for the breaking of seed dormancy. OBJECTIVE: The current study reports on the nutritional status of 5 month old field grown plants regenerated from cryostored and control seeds. MATERIALS AND METHODS: Biomass (fresh and dry mass of leaves and stems) and contents of ash, neutral detergent fiber, acid detergent fiber, lignin, cellulose, crude protein, P, Ca, Mg and K were measured. RESULTS: Seeds germinated and emerged faster following immersion in liquid nitrogen (LN) which was supported by quantitative evaluations of fresh and dry weights per m2. However, the ratio of leaf:stem mass were not altered by seed exposure to LN. CONCLUSION: The results showed that exposure of seeds to cryogenic temperatures did not alter the nutritional composition of regenerated plants.


Assuntos
Criopreservação , Fabaceae/química , Estado Nutricional , Sementes/fisiologia , Germinação , Nitrogênio
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